Sync with 2.7.1
[git] / sha1_file.c
1 /*
2  * GIT - The information manager from hell
3  *
4  * Copyright (C) Linus Torvalds, 2005
5  *
6  * This handles basic git sha1 object files - packing, unpacking,
7  * creation etc.
8  */
9 #include "cache.h"
10 #include "string-list.h"
11 #include "lockfile.h"
12 #include "delta.h"
13 #include "pack.h"
14 #include "blob.h"
15 #include "commit.h"
16 #include "run-command.h"
17 #include "tag.h"
18 #include "tree.h"
19 #include "tree-walk.h"
20 #include "refs.h"
21 #include "pack-revindex.h"
22 #include "sha1-lookup.h"
23 #include "bulk-checkin.h"
24 #include "streaming.h"
25 #include "dir.h"
26
27 #ifndef O_NOATIME
28 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
29 #define O_NOATIME 01000000
30 #else
31 #define O_NOATIME 0
32 #endif
33 #endif
34
35 #define SZ_FMT PRIuMAX
36 static inline uintmax_t sz_fmt(size_t s) { return s; }
37
38 const unsigned char null_sha1[20];
39 const struct object_id null_oid;
40
41 /*
42  * This is meant to hold a *small* number of objects that you would
43  * want read_sha1_file() to be able to return, but yet you do not want
44  * to write them into the object store (e.g. a browse-only
45  * application).
46  */
47 static struct cached_object {
48         unsigned char sha1[20];
49         enum object_type type;
50         void *buf;
51         unsigned long size;
52 } *cached_objects;
53 static int cached_object_nr, cached_object_alloc;
54
55 static struct cached_object empty_tree = {
56         EMPTY_TREE_SHA1_BIN_LITERAL,
57         OBJ_TREE,
58         "",
59         0
60 };
61
62 /*
63  * A pointer to the last packed_git in which an object was found.
64  * When an object is sought, we look in this packfile first, because
65  * objects that are looked up at similar times are often in the same
66  * packfile as one another.
67  */
68 static struct packed_git *last_found_pack;
69
70 static struct cached_object *find_cached_object(const unsigned char *sha1)
71 {
72         int i;
73         struct cached_object *co = cached_objects;
74
75         for (i = 0; i < cached_object_nr; i++, co++) {
76                 if (!hashcmp(co->sha1, sha1))
77                         return co;
78         }
79         if (!hashcmp(sha1, empty_tree.sha1))
80                 return &empty_tree;
81         return NULL;
82 }
83
84 int mkdir_in_gitdir(const char *path)
85 {
86         if (mkdir(path, 0777)) {
87                 int saved_errno = errno;
88                 struct stat st;
89                 struct strbuf sb = STRBUF_INIT;
90
91                 if (errno != EEXIST)
92                         return -1;
93                 /*
94                  * Are we looking at a path in a symlinked worktree
95                  * whose original repository does not yet have it?
96                  * e.g. .git/rr-cache pointing at its original
97                  * repository in which the user hasn't performed any
98                  * conflict resolution yet?
99                  */
100                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
101                     strbuf_readlink(&sb, path, st.st_size) ||
102                     !is_absolute_path(sb.buf) ||
103                     mkdir(sb.buf, 0777)) {
104                         strbuf_release(&sb);
105                         errno = saved_errno;
106                         return -1;
107                 }
108                 strbuf_release(&sb);
109         }
110         return adjust_shared_perm(path);
111 }
112
113 enum scld_error safe_create_leading_directories(char *path)
114 {
115         char *next_component = path + offset_1st_component(path);
116         enum scld_error ret = SCLD_OK;
117
118         while (ret == SCLD_OK && next_component) {
119                 struct stat st;
120                 char *slash = next_component, slash_character;
121
122                 while (*slash && !is_dir_sep(*slash))
123                         slash++;
124
125                 if (!*slash)
126                         break;
127
128                 next_component = slash + 1;
129                 while (is_dir_sep(*next_component))
130                         next_component++;
131                 if (!*next_component)
132                         break;
133
134                 slash_character = *slash;
135                 *slash = '\0';
136                 if (!stat(path, &st)) {
137                         /* path exists */
138                         if (!S_ISDIR(st.st_mode))
139                                 ret = SCLD_EXISTS;
140                 } else if (mkdir(path, 0777)) {
141                         if (errno == EEXIST &&
142                             !stat(path, &st) && S_ISDIR(st.st_mode))
143                                 ; /* somebody created it since we checked */
144                         else if (errno == ENOENT)
145                                 /*
146                                  * Either mkdir() failed because
147                                  * somebody just pruned the containing
148                                  * directory, or stat() failed because
149                                  * the file that was in our way was
150                                  * just removed.  Either way, inform
151                                  * the caller that it might be worth
152                                  * trying again:
153                                  */
154                                 ret = SCLD_VANISHED;
155                         else
156                                 ret = SCLD_FAILED;
157                 } else if (adjust_shared_perm(path)) {
158                         ret = SCLD_PERMS;
159                 }
160                 *slash = slash_character;
161         }
162         return ret;
163 }
164
165 enum scld_error safe_create_leading_directories_const(const char *path)
166 {
167         /* path points to cache entries, so xstrdup before messing with it */
168         char *buf = xstrdup(path);
169         enum scld_error result = safe_create_leading_directories(buf);
170         free(buf);
171         return result;
172 }
173
174 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
175 {
176         int i;
177         for (i = 0; i < 20; i++) {
178                 static char hex[] = "0123456789abcdef";
179                 unsigned int val = sha1[i];
180                 char *pos = pathbuf + i*2 + (i > 0);
181                 *pos++ = hex[val >> 4];
182                 *pos = hex[val & 0xf];
183         }
184 }
185
186 const char *sha1_file_name(const unsigned char *sha1)
187 {
188         static char buf[PATH_MAX];
189         const char *objdir;
190         int len;
191
192         objdir = get_object_directory();
193         len = strlen(objdir);
194
195         /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
196         if (len + 43 > PATH_MAX)
197                 die("insanely long object directory %s", objdir);
198         memcpy(buf, objdir, len);
199         buf[len] = '/';
200         buf[len+3] = '/';
201         buf[len+42] = '\0';
202         fill_sha1_path(buf + len + 1, sha1);
203         return buf;
204 }
205
206 /*
207  * Return the name of the pack or index file with the specified sha1
208  * in its filename.  *base and *name are scratch space that must be
209  * provided by the caller.  which should be "pack" or "idx".
210  */
211 static char *sha1_get_pack_name(const unsigned char *sha1,
212                                 struct strbuf *buf,
213                                 const char *which)
214 {
215         strbuf_reset(buf);
216         strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
217                     sha1_to_hex(sha1), which);
218         return buf->buf;
219 }
220
221 char *sha1_pack_name(const unsigned char *sha1)
222 {
223         static struct strbuf buf = STRBUF_INIT;
224         return sha1_get_pack_name(sha1, &buf, "pack");
225 }
226
227 char *sha1_pack_index_name(const unsigned char *sha1)
228 {
229         static struct strbuf buf = STRBUF_INIT;
230         return sha1_get_pack_name(sha1, &buf, "idx");
231 }
232
233 struct alternate_object_database *alt_odb_list;
234 static struct alternate_object_database **alt_odb_tail;
235
236 /*
237  * Prepare alternate object database registry.
238  *
239  * The variable alt_odb_list points at the list of struct
240  * alternate_object_database.  The elements on this list come from
241  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
242  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
243  * whose contents is similar to that environment variable but can be
244  * LF separated.  Its base points at a statically allocated buffer that
245  * contains "/the/directory/corresponding/to/.git/objects/...", while
246  * its name points just after the slash at the end of ".git/objects/"
247  * in the example above, and has enough space to hold 40-byte hex
248  * SHA1, an extra slash for the first level indirection, and the
249  * terminating NUL.
250  */
251 static int link_alt_odb_entry(const char *entry, const char *relative_base,
252         int depth, const char *normalized_objdir)
253 {
254         struct alternate_object_database *ent;
255         struct alternate_object_database *alt;
256         int pfxlen, entlen;
257         struct strbuf pathbuf = STRBUF_INIT;
258
259         if (!is_absolute_path(entry) && relative_base) {
260                 strbuf_addstr(&pathbuf, real_path(relative_base));
261                 strbuf_addch(&pathbuf, '/');
262         }
263         strbuf_addstr(&pathbuf, entry);
264
265         normalize_path_copy(pathbuf.buf, pathbuf.buf);
266
267         pfxlen = strlen(pathbuf.buf);
268
269         /*
270          * The trailing slash after the directory name is given by
271          * this function at the end. Remove duplicates.
272          */
273         while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
274                 pfxlen -= 1;
275
276         entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
277         ent = xmalloc(sizeof(*ent) + entlen);
278         memcpy(ent->base, pathbuf.buf, pfxlen);
279         strbuf_release(&pathbuf);
280
281         ent->name = ent->base + pfxlen + 1;
282         ent->base[pfxlen + 3] = '/';
283         ent->base[pfxlen] = ent->base[entlen-1] = 0;
284
285         /* Detect cases where alternate disappeared */
286         if (!is_directory(ent->base)) {
287                 error("object directory %s does not exist; "
288                       "check .git/objects/info/alternates.",
289                       ent->base);
290                 free(ent);
291                 return -1;
292         }
293
294         /* Prevent the common mistake of listing the same
295          * thing twice, or object directory itself.
296          */
297         for (alt = alt_odb_list; alt; alt = alt->next) {
298                 if (pfxlen == alt->name - alt->base - 1 &&
299                     !memcmp(ent->base, alt->base, pfxlen)) {
300                         free(ent);
301                         return -1;
302                 }
303         }
304         if (!strcmp_icase(ent->base, normalized_objdir)) {
305                 free(ent);
306                 return -1;
307         }
308
309         /* add the alternate entry */
310         *alt_odb_tail = ent;
311         alt_odb_tail = &(ent->next);
312         ent->next = NULL;
313
314         /* recursively add alternates */
315         read_info_alternates(ent->base, depth + 1);
316
317         ent->base[pfxlen] = '/';
318
319         return 0;
320 }
321
322 static void link_alt_odb_entries(const char *alt, int len, int sep,
323                                  const char *relative_base, int depth)
324 {
325         struct string_list entries = STRING_LIST_INIT_NODUP;
326         char *alt_copy;
327         int i;
328         struct strbuf objdirbuf = STRBUF_INIT;
329
330         if (depth > 5) {
331                 error("%s: ignoring alternate object stores, nesting too deep.",
332                                 relative_base);
333                 return;
334         }
335
336         strbuf_add_absolute_path(&objdirbuf, get_object_directory());
337         normalize_path_copy(objdirbuf.buf, objdirbuf.buf);
338
339         alt_copy = xmemdupz(alt, len);
340         string_list_split_in_place(&entries, alt_copy, sep, -1);
341         for (i = 0; i < entries.nr; i++) {
342                 const char *entry = entries.items[i].string;
343                 if (entry[0] == '\0' || entry[0] == '#')
344                         continue;
345                 if (!is_absolute_path(entry) && depth) {
346                         error("%s: ignoring relative alternate object store %s",
347                                         relative_base, entry);
348                 } else {
349                         link_alt_odb_entry(entry, relative_base, depth, objdirbuf.buf);
350                 }
351         }
352         string_list_clear(&entries, 0);
353         free(alt_copy);
354         strbuf_release(&objdirbuf);
355 }
356
357 void read_info_alternates(const char * relative_base, int depth)
358 {
359         char *map;
360         size_t mapsz;
361         struct stat st;
362         char *path;
363         int fd;
364
365         path = xstrfmt("%s/info/alternates", relative_base);
366         fd = git_open_noatime(path);
367         free(path);
368         if (fd < 0)
369                 return;
370         if (fstat(fd, &st) || (st.st_size == 0)) {
371                 close(fd);
372                 return;
373         }
374         mapsz = xsize_t(st.st_size);
375         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
376         close(fd);
377
378         link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
379
380         munmap(map, mapsz);
381 }
382
383 void add_to_alternates_file(const char *reference)
384 {
385         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
386         char *alts = git_pathdup("objects/info/alternates");
387         FILE *in, *out;
388
389         hold_lock_file_for_update(lock, alts, LOCK_DIE_ON_ERROR);
390         out = fdopen_lock_file(lock, "w");
391         if (!out)
392                 die_errno("unable to fdopen alternates lockfile");
393
394         in = fopen(alts, "r");
395         if (in) {
396                 struct strbuf line = STRBUF_INIT;
397                 int found = 0;
398
399                 while (strbuf_getline(&line, in) != EOF) {
400                         if (!strcmp(reference, line.buf)) {
401                                 found = 1;
402                                 break;
403                         }
404                         fprintf_or_die(out, "%s\n", line.buf);
405                 }
406
407                 strbuf_release(&line);
408                 fclose(in);
409
410                 if (found) {
411                         rollback_lock_file(lock);
412                         lock = NULL;
413                 }
414         }
415         else if (errno != ENOENT)
416                 die_errno("unable to read alternates file");
417
418         if (lock) {
419                 fprintf_or_die(out, "%s\n", reference);
420                 if (commit_lock_file(lock))
421                         die_errno("unable to move new alternates file into place");
422                 if (alt_odb_tail)
423                         link_alt_odb_entries(reference, strlen(reference), '\n', NULL, 0);
424         }
425         free(alts);
426 }
427
428 int foreach_alt_odb(alt_odb_fn fn, void *cb)
429 {
430         struct alternate_object_database *ent;
431         int r = 0;
432
433         prepare_alt_odb();
434         for (ent = alt_odb_list; ent; ent = ent->next) {
435                 r = fn(ent, cb);
436                 if (r)
437                         break;
438         }
439         return r;
440 }
441
442 void prepare_alt_odb(void)
443 {
444         const char *alt;
445
446         if (alt_odb_tail)
447                 return;
448
449         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
450         if (!alt) alt = "";
451
452         alt_odb_tail = &alt_odb_list;
453         link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
454
455         read_info_alternates(get_object_directory(), 0);
456 }
457
458 /* Returns 1 if we have successfully freshened the file, 0 otherwise. */
459 static int freshen_file(const char *fn)
460 {
461         struct utimbuf t;
462         t.actime = t.modtime = time(NULL);
463         return !utime(fn, &t);
464 }
465
466 /*
467  * All of the check_and_freshen functions return 1 if the file exists and was
468  * freshened (if freshening was requested), 0 otherwise. If they return
469  * 0, you should not assume that it is safe to skip a write of the object (it
470  * either does not exist on disk, or has a stale mtime and may be subject to
471  * pruning).
472  */
473 static int check_and_freshen_file(const char *fn, int freshen)
474 {
475         if (access(fn, F_OK))
476                 return 0;
477         if (freshen && !freshen_file(fn))
478                 return 0;
479         return 1;
480 }
481
482 static int check_and_freshen_local(const unsigned char *sha1, int freshen)
483 {
484         return check_and_freshen_file(sha1_file_name(sha1), freshen);
485 }
486
487 static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
488 {
489         struct alternate_object_database *alt;
490         prepare_alt_odb();
491         for (alt = alt_odb_list; alt; alt = alt->next) {
492                 fill_sha1_path(alt->name, sha1);
493                 if (check_and_freshen_file(alt->base, freshen))
494                         return 1;
495         }
496         return 0;
497 }
498
499 static int check_and_freshen(const unsigned char *sha1, int freshen)
500 {
501         return check_and_freshen_local(sha1, freshen) ||
502                check_and_freshen_nonlocal(sha1, freshen);
503 }
504
505 int has_loose_object_nonlocal(const unsigned char *sha1)
506 {
507         return check_and_freshen_nonlocal(sha1, 0);
508 }
509
510 static int has_loose_object(const unsigned char *sha1)
511 {
512         return check_and_freshen(sha1, 0);
513 }
514
515 static unsigned int pack_used_ctr;
516 static unsigned int pack_mmap_calls;
517 static unsigned int peak_pack_open_windows;
518 static unsigned int pack_open_windows;
519 static unsigned int pack_open_fds;
520 static unsigned int pack_max_fds;
521 static size_t peak_pack_mapped;
522 static size_t pack_mapped;
523 struct packed_git *packed_git;
524
525 void pack_report(void)
526 {
527         fprintf(stderr,
528                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
529                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
530                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
531                 sz_fmt(getpagesize()),
532                 sz_fmt(packed_git_window_size),
533                 sz_fmt(packed_git_limit));
534         fprintf(stderr,
535                 "pack_report: pack_used_ctr            = %10u\n"
536                 "pack_report: pack_mmap_calls          = %10u\n"
537                 "pack_report: pack_open_windows        = %10u / %10u\n"
538                 "pack_report: pack_mapped              = "
539                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
540                 pack_used_ctr,
541                 pack_mmap_calls,
542                 pack_open_windows, peak_pack_open_windows,
543                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
544 }
545
546 /*
547  * Open and mmap the index file at path, perform a couple of
548  * consistency checks, then record its information to p.  Return 0 on
549  * success.
550  */
551 static int check_packed_git_idx(const char *path, struct packed_git *p)
552 {
553         void *idx_map;
554         struct pack_idx_header *hdr;
555         size_t idx_size;
556         uint32_t version, nr, i, *index;
557         int fd = git_open_noatime(path);
558         struct stat st;
559
560         if (fd < 0)
561                 return -1;
562         if (fstat(fd, &st)) {
563                 close(fd);
564                 return -1;
565         }
566         idx_size = xsize_t(st.st_size);
567         if (idx_size < 4 * 256 + 20 + 20) {
568                 close(fd);
569                 return error("index file %s is too small", path);
570         }
571         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
572         close(fd);
573
574         hdr = idx_map;
575         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
576                 version = ntohl(hdr->idx_version);
577                 if (version < 2 || version > 2) {
578                         munmap(idx_map, idx_size);
579                         return error("index file %s is version %"PRIu32
580                                      " and is not supported by this binary"
581                                      " (try upgrading GIT to a newer version)",
582                                      path, version);
583                 }
584         } else
585                 version = 1;
586
587         nr = 0;
588         index = idx_map;
589         if (version > 1)
590                 index += 2;  /* skip index header */
591         for (i = 0; i < 256; i++) {
592                 uint32_t n = ntohl(index[i]);
593                 if (n < nr) {
594                         munmap(idx_map, idx_size);
595                         return error("non-monotonic index %s", path);
596                 }
597                 nr = n;
598         }
599
600         if (version == 1) {
601                 /*
602                  * Total size:
603                  *  - 256 index entries 4 bytes each
604                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
605                  *  - 20-byte SHA1 of the packfile
606                  *  - 20-byte SHA1 file checksum
607                  */
608                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
609                         munmap(idx_map, idx_size);
610                         return error("wrong index v1 file size in %s", path);
611                 }
612         } else if (version == 2) {
613                 /*
614                  * Minimum size:
615                  *  - 8 bytes of header
616                  *  - 256 index entries 4 bytes each
617                  *  - 20-byte sha1 entry * nr
618                  *  - 4-byte crc entry * nr
619                  *  - 4-byte offset entry * nr
620                  *  - 20-byte SHA1 of the packfile
621                  *  - 20-byte SHA1 file checksum
622                  * And after the 4-byte offset table might be a
623                  * variable sized table containing 8-byte entries
624                  * for offsets larger than 2^31.
625                  */
626                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
627                 unsigned long max_size = min_size;
628                 if (nr)
629                         max_size += (nr - 1)*8;
630                 if (idx_size < min_size || idx_size > max_size) {
631                         munmap(idx_map, idx_size);
632                         return error("wrong index v2 file size in %s", path);
633                 }
634                 if (idx_size != min_size &&
635                     /*
636                      * make sure we can deal with large pack offsets.
637                      * 31-bit signed offset won't be enough, neither
638                      * 32-bit unsigned one will be.
639                      */
640                     (sizeof(off_t) <= 4)) {
641                         munmap(idx_map, idx_size);
642                         return error("pack too large for current definition of off_t in %s", path);
643                 }
644         }
645
646         p->index_version = version;
647         p->index_data = idx_map;
648         p->index_size = idx_size;
649         p->num_objects = nr;
650         return 0;
651 }
652
653 int open_pack_index(struct packed_git *p)
654 {
655         char *idx_name;
656         size_t len;
657         int ret;
658
659         if (p->index_data)
660                 return 0;
661
662         if (!strip_suffix(p->pack_name, ".pack", &len))
663                 die("BUG: pack_name does not end in .pack");
664         idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
665         ret = check_packed_git_idx(idx_name, p);
666         free(idx_name);
667         return ret;
668 }
669
670 static void scan_windows(struct packed_git *p,
671         struct packed_git **lru_p,
672         struct pack_window **lru_w,
673         struct pack_window **lru_l)
674 {
675         struct pack_window *w, *w_l;
676
677         for (w_l = NULL, w = p->windows; w; w = w->next) {
678                 if (!w->inuse_cnt) {
679                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
680                                 *lru_p = p;
681                                 *lru_w = w;
682                                 *lru_l = w_l;
683                         }
684                 }
685                 w_l = w;
686         }
687 }
688
689 static int unuse_one_window(struct packed_git *current)
690 {
691         struct packed_git *p, *lru_p = NULL;
692         struct pack_window *lru_w = NULL, *lru_l = NULL;
693
694         if (current)
695                 scan_windows(current, &lru_p, &lru_w, &lru_l);
696         for (p = packed_git; p; p = p->next)
697                 scan_windows(p, &lru_p, &lru_w, &lru_l);
698         if (lru_p) {
699                 munmap(lru_w->base, lru_w->len);
700                 pack_mapped -= lru_w->len;
701                 if (lru_l)
702                         lru_l->next = lru_w->next;
703                 else
704                         lru_p->windows = lru_w->next;
705                 free(lru_w);
706                 pack_open_windows--;
707                 return 1;
708         }
709         return 0;
710 }
711
712 void release_pack_memory(size_t need)
713 {
714         size_t cur = pack_mapped;
715         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
716                 ; /* nothing */
717 }
718
719 static void mmap_limit_check(size_t length)
720 {
721         static size_t limit = 0;
722         if (!limit) {
723                 limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
724                 if (!limit)
725                         limit = SIZE_MAX;
726         }
727         if (length > limit)
728                 die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
729                     (uintmax_t)length, (uintmax_t)limit);
730 }
731
732 void *xmmap_gently(void *start, size_t length,
733                   int prot, int flags, int fd, off_t offset)
734 {
735         void *ret;
736
737         mmap_limit_check(length);
738         ret = mmap(start, length, prot, flags, fd, offset);
739         if (ret == MAP_FAILED) {
740                 if (!length)
741                         return NULL;
742                 release_pack_memory(length);
743                 ret = mmap(start, length, prot, flags, fd, offset);
744         }
745         return ret;
746 }
747
748 void *xmmap(void *start, size_t length,
749         int prot, int flags, int fd, off_t offset)
750 {
751         void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
752         if (ret == MAP_FAILED)
753                 die_errno("mmap failed");
754         return ret;
755 }
756
757 void close_pack_windows(struct packed_git *p)
758 {
759         while (p->windows) {
760                 struct pack_window *w = p->windows;
761
762                 if (w->inuse_cnt)
763                         die("pack '%s' still has open windows to it",
764                             p->pack_name);
765                 munmap(w->base, w->len);
766                 pack_mapped -= w->len;
767                 pack_open_windows--;
768                 p->windows = w->next;
769                 free(w);
770         }
771 }
772
773 static int close_pack_fd(struct packed_git *p)
774 {
775         if (p->pack_fd < 0)
776                 return 0;
777
778         close(p->pack_fd);
779         pack_open_fds--;
780         p->pack_fd = -1;
781
782         return 1;
783 }
784
785 static void close_pack(struct packed_git *p)
786 {
787         close_pack_windows(p);
788         close_pack_fd(p);
789         close_pack_index(p);
790 }
791
792 void close_all_packs(void)
793 {
794         struct packed_git *p;
795
796         for (p = packed_git; p; p = p->next)
797                 if (p->do_not_close)
798                         die("BUG! Want to close pack marked 'do-not-close'");
799                 else
800                         close_pack(p);
801 }
802
803
804 /*
805  * The LRU pack is the one with the oldest MRU window, preferring packs
806  * with no used windows, or the oldest mtime if it has no windows allocated.
807  */
808 static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
809 {
810         struct pack_window *w, *this_mru_w;
811         int has_windows_inuse = 0;
812
813         /*
814          * Reject this pack if it has windows and the previously selected
815          * one does not.  If this pack does not have windows, reject
816          * it if the pack file is newer than the previously selected one.
817          */
818         if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
819                 return;
820
821         for (w = this_mru_w = p->windows; w; w = w->next) {
822                 /*
823                  * Reject this pack if any of its windows are in use,
824                  * but the previously selected pack did not have any
825                  * inuse windows.  Otherwise, record that this pack
826                  * has windows in use.
827                  */
828                 if (w->inuse_cnt) {
829                         if (*accept_windows_inuse)
830                                 has_windows_inuse = 1;
831                         else
832                                 return;
833                 }
834
835                 if (w->last_used > this_mru_w->last_used)
836                         this_mru_w = w;
837
838                 /*
839                  * Reject this pack if it has windows that have been
840                  * used more recently than the previously selected pack.
841                  * If the previously selected pack had windows inuse and
842                  * we have not encountered a window in this pack that is
843                  * inuse, skip this check since we prefer a pack with no
844                  * inuse windows to one that has inuse windows.
845                  */
846                 if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
847                     this_mru_w->last_used > (*mru_w)->last_used)
848                         return;
849         }
850
851         /*
852          * Select this pack.
853          */
854         *mru_w = this_mru_w;
855         *lru_p = p;
856         *accept_windows_inuse = has_windows_inuse;
857 }
858
859 static int close_one_pack(void)
860 {
861         struct packed_git *p, *lru_p = NULL;
862         struct pack_window *mru_w = NULL;
863         int accept_windows_inuse = 1;
864
865         for (p = packed_git; p; p = p->next) {
866                 if (p->pack_fd == -1)
867                         continue;
868                 find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
869         }
870
871         if (lru_p)
872                 return close_pack_fd(lru_p);
873
874         return 0;
875 }
876
877 void unuse_pack(struct pack_window **w_cursor)
878 {
879         struct pack_window *w = *w_cursor;
880         if (w) {
881                 w->inuse_cnt--;
882                 *w_cursor = NULL;
883         }
884 }
885
886 void close_pack_index(struct packed_git *p)
887 {
888         if (p->index_data) {
889                 munmap((void *)p->index_data, p->index_size);
890                 p->index_data = NULL;
891         }
892 }
893
894 /*
895  * This is used by git-repack in case a newly created pack happens to
896  * contain the same set of objects as an existing one.  In that case
897  * the resulting file might be different even if its name would be the
898  * same.  It is best to close any reference to the old pack before it is
899  * replaced on disk.  Of course no index pointers or windows for given pack
900  * must subsist at this point.  If ever objects from this pack are requested
901  * again, the new version of the pack will be reinitialized through
902  * reprepare_packed_git().
903  */
904 void free_pack_by_name(const char *pack_name)
905 {
906         struct packed_git *p, **pp = &packed_git;
907
908         while (*pp) {
909                 p = *pp;
910                 if (strcmp(pack_name, p->pack_name) == 0) {
911                         clear_delta_base_cache();
912                         close_pack(p);
913                         free(p->bad_object_sha1);
914                         *pp = p->next;
915                         if (last_found_pack == p)
916                                 last_found_pack = NULL;
917                         free(p);
918                         return;
919                 }
920                 pp = &p->next;
921         }
922 }
923
924 static unsigned int get_max_fd_limit(void)
925 {
926 #ifdef RLIMIT_NOFILE
927         {
928                 struct rlimit lim;
929
930                 if (!getrlimit(RLIMIT_NOFILE, &lim))
931                         return lim.rlim_cur;
932         }
933 #endif
934
935 #ifdef _SC_OPEN_MAX
936         {
937                 long open_max = sysconf(_SC_OPEN_MAX);
938                 if (0 < open_max)
939                         return open_max;
940                 /*
941                  * Otherwise, we got -1 for one of the two
942                  * reasons:
943                  *
944                  * (1) sysconf() did not understand _SC_OPEN_MAX
945                  *     and signaled an error with -1; or
946                  * (2) sysconf() said there is no limit.
947                  *
948                  * We _could_ clear errno before calling sysconf() to
949                  * tell these two cases apart and return a huge number
950                  * in the latter case to let the caller cap it to a
951                  * value that is not so selfish, but letting the
952                  * fallback OPEN_MAX codepath take care of these cases
953                  * is a lot simpler.
954                  */
955         }
956 #endif
957
958 #ifdef OPEN_MAX
959         return OPEN_MAX;
960 #else
961         return 1; /* see the caller ;-) */
962 #endif
963 }
964
965 /*
966  * Do not call this directly as this leaks p->pack_fd on error return;
967  * call open_packed_git() instead.
968  */
969 static int open_packed_git_1(struct packed_git *p)
970 {
971         struct stat st;
972         struct pack_header hdr;
973         unsigned char sha1[20];
974         unsigned char *idx_sha1;
975         long fd_flag;
976
977         if (!p->index_data && open_pack_index(p))
978                 return error("packfile %s index unavailable", p->pack_name);
979
980         if (!pack_max_fds) {
981                 unsigned int max_fds = get_max_fd_limit();
982
983                 /* Save 3 for stdin/stdout/stderr, 22 for work */
984                 if (25 < max_fds)
985                         pack_max_fds = max_fds - 25;
986                 else
987                         pack_max_fds = 1;
988         }
989
990         while (pack_max_fds <= pack_open_fds && close_one_pack())
991                 ; /* nothing */
992
993         p->pack_fd = git_open_noatime(p->pack_name);
994         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
995                 return -1;
996         pack_open_fds++;
997
998         /* If we created the struct before we had the pack we lack size. */
999         if (!p->pack_size) {
1000                 if (!S_ISREG(st.st_mode))
1001                         return error("packfile %s not a regular file", p->pack_name);
1002                 p->pack_size = st.st_size;
1003         } else if (p->pack_size != st.st_size)
1004                 return error("packfile %s size changed", p->pack_name);
1005
1006         /* We leave these file descriptors open with sliding mmap;
1007          * there is no point keeping them open across exec(), though.
1008          */
1009         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
1010         if (fd_flag < 0)
1011                 return error("cannot determine file descriptor flags");
1012         fd_flag |= FD_CLOEXEC;
1013         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
1014                 return error("cannot set FD_CLOEXEC");
1015
1016         /* Verify we recognize this pack file format. */
1017         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
1018                 return error("file %s is far too short to be a packfile", p->pack_name);
1019         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
1020                 return error("file %s is not a GIT packfile", p->pack_name);
1021         if (!pack_version_ok(hdr.hdr_version))
1022                 return error("packfile %s is version %"PRIu32" and not"
1023                         " supported (try upgrading GIT to a newer version)",
1024                         p->pack_name, ntohl(hdr.hdr_version));
1025
1026         /* Verify the pack matches its index. */
1027         if (p->num_objects != ntohl(hdr.hdr_entries))
1028                 return error("packfile %s claims to have %"PRIu32" objects"
1029                              " while index indicates %"PRIu32" objects",
1030                              p->pack_name, ntohl(hdr.hdr_entries),
1031                              p->num_objects);
1032         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
1033                 return error("end of packfile %s is unavailable", p->pack_name);
1034         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
1035                 return error("packfile %s signature is unavailable", p->pack_name);
1036         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
1037         if (hashcmp(sha1, idx_sha1))
1038                 return error("packfile %s does not match index", p->pack_name);
1039         return 0;
1040 }
1041
1042 static int open_packed_git(struct packed_git *p)
1043 {
1044         if (!open_packed_git_1(p))
1045                 return 0;
1046         close_pack_fd(p);
1047         return -1;
1048 }
1049
1050 static int in_window(struct pack_window *win, off_t offset)
1051 {
1052         /* We must promise at least 20 bytes (one hash) after the
1053          * offset is available from this window, otherwise the offset
1054          * is not actually in this window and a different window (which
1055          * has that one hash excess) must be used.  This is to support
1056          * the object header and delta base parsing routines below.
1057          */
1058         off_t win_off = win->offset;
1059         return win_off <= offset
1060                 && (offset + 20) <= (win_off + win->len);
1061 }
1062
1063 unsigned char *use_pack(struct packed_git *p,
1064                 struct pack_window **w_cursor,
1065                 off_t offset,
1066                 unsigned long *left)
1067 {
1068         struct pack_window *win = *w_cursor;
1069
1070         /* Since packfiles end in a hash of their content and it's
1071          * pointless to ask for an offset into the middle of that
1072          * hash, and the in_window function above wouldn't match
1073          * don't allow an offset too close to the end of the file.
1074          */
1075         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
1076                 die("packfile %s cannot be accessed", p->pack_name);
1077         if (offset > (p->pack_size - 20))
1078                 die("offset beyond end of packfile (truncated pack?)");
1079
1080         if (!win || !in_window(win, offset)) {
1081                 if (win)
1082                         win->inuse_cnt--;
1083                 for (win = p->windows; win; win = win->next) {
1084                         if (in_window(win, offset))
1085                                 break;
1086                 }
1087                 if (!win) {
1088                         size_t window_align = packed_git_window_size / 2;
1089                         off_t len;
1090
1091                         if (p->pack_fd == -1 && open_packed_git(p))
1092                                 die("packfile %s cannot be accessed", p->pack_name);
1093
1094                         win = xcalloc(1, sizeof(*win));
1095                         win->offset = (offset / window_align) * window_align;
1096                         len = p->pack_size - win->offset;
1097                         if (len > packed_git_window_size)
1098                                 len = packed_git_window_size;
1099                         win->len = (size_t)len;
1100                         pack_mapped += win->len;
1101                         while (packed_git_limit < pack_mapped
1102                                 && unuse_one_window(p))
1103                                 ; /* nothing */
1104                         win->base = xmmap(NULL, win->len,
1105                                 PROT_READ, MAP_PRIVATE,
1106                                 p->pack_fd, win->offset);
1107                         if (win->base == MAP_FAILED)
1108                                 die("packfile %s cannot be mapped: %s",
1109                                         p->pack_name,
1110                                         strerror(errno));
1111                         if (!win->offset && win->len == p->pack_size
1112                                 && !p->do_not_close)
1113                                 close_pack_fd(p);
1114                         pack_mmap_calls++;
1115                         pack_open_windows++;
1116                         if (pack_mapped > peak_pack_mapped)
1117                                 peak_pack_mapped = pack_mapped;
1118                         if (pack_open_windows > peak_pack_open_windows)
1119                                 peak_pack_open_windows = pack_open_windows;
1120                         win->next = p->windows;
1121                         p->windows = win;
1122                 }
1123         }
1124         if (win != *w_cursor) {
1125                 win->last_used = pack_used_ctr++;
1126                 win->inuse_cnt++;
1127                 *w_cursor = win;
1128         }
1129         offset -= win->offset;
1130         if (left)
1131                 *left = win->len - xsize_t(offset);
1132         return win->base + offset;
1133 }
1134
1135 static struct packed_git *alloc_packed_git(int extra)
1136 {
1137         struct packed_git *p = xmalloc(sizeof(*p) + extra);
1138         memset(p, 0, sizeof(*p));
1139         p->pack_fd = -1;
1140         return p;
1141 }
1142
1143 static void try_to_free_pack_memory(size_t size)
1144 {
1145         release_pack_memory(size);
1146 }
1147
1148 struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
1149 {
1150         static int have_set_try_to_free_routine;
1151         struct stat st;
1152         size_t alloc;
1153         struct packed_git *p;
1154
1155         if (!have_set_try_to_free_routine) {
1156                 have_set_try_to_free_routine = 1;
1157                 set_try_to_free_routine(try_to_free_pack_memory);
1158         }
1159
1160         /*
1161          * Make sure a corresponding .pack file exists and that
1162          * the index looks sane.
1163          */
1164         if (!strip_suffix_mem(path, &path_len, ".idx"))
1165                 return NULL;
1166
1167         /*
1168          * ".pack" is long enough to hold any suffix we're adding (and
1169          * the use xsnprintf double-checks that)
1170          */
1171         alloc = path_len + strlen(".pack") + 1;
1172         p = alloc_packed_git(alloc);
1173         memcpy(p->pack_name, path, path_len);
1174
1175         xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
1176         if (!access(p->pack_name, F_OK))
1177                 p->pack_keep = 1;
1178
1179         xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
1180         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
1181                 free(p);
1182                 return NULL;
1183         }
1184
1185         /* ok, it looks sane as far as we can check without
1186          * actually mapping the pack file.
1187          */
1188         p->pack_size = st.st_size;
1189         p->pack_local = local;
1190         p->mtime = st.st_mtime;
1191         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
1192                 hashclr(p->sha1);
1193         return p;
1194 }
1195
1196 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
1197 {
1198         const char *path = sha1_pack_name(sha1);
1199         int alloc = strlen(path) + 1;
1200         struct packed_git *p = alloc_packed_git(alloc);
1201
1202         memcpy(p->pack_name, path, alloc); /* includes NUL */
1203         hashcpy(p->sha1, sha1);
1204         if (check_packed_git_idx(idx_path, p)) {
1205                 free(p);
1206                 return NULL;
1207         }
1208
1209         return p;
1210 }
1211
1212 void install_packed_git(struct packed_git *pack)
1213 {
1214         if (pack->pack_fd != -1)
1215                 pack_open_fds++;
1216
1217         pack->next = packed_git;
1218         packed_git = pack;
1219 }
1220
1221 void (*report_garbage)(unsigned seen_bits, const char *path);
1222
1223 static void report_helper(const struct string_list *list,
1224                           int seen_bits, int first, int last)
1225 {
1226         if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
1227                 return;
1228
1229         for (; first < last; first++)
1230                 report_garbage(seen_bits, list->items[first].string);
1231 }
1232
1233 static void report_pack_garbage(struct string_list *list)
1234 {
1235         int i, baselen = -1, first = 0, seen_bits = 0;
1236
1237         if (!report_garbage)
1238                 return;
1239
1240         string_list_sort(list);
1241
1242         for (i = 0; i < list->nr; i++) {
1243                 const char *path = list->items[i].string;
1244                 if (baselen != -1 &&
1245                     strncmp(path, list->items[first].string, baselen)) {
1246                         report_helper(list, seen_bits, first, i);
1247                         baselen = -1;
1248                         seen_bits = 0;
1249                 }
1250                 if (baselen == -1) {
1251                         const char *dot = strrchr(path, '.');
1252                         if (!dot) {
1253                                 report_garbage(PACKDIR_FILE_GARBAGE, path);
1254                                 continue;
1255                         }
1256                         baselen = dot - path + 1;
1257                         first = i;
1258                 }
1259                 if (!strcmp(path + baselen, "pack"))
1260                         seen_bits |= 1;
1261                 else if (!strcmp(path + baselen, "idx"))
1262                         seen_bits |= 2;
1263         }
1264         report_helper(list, seen_bits, first, list->nr);
1265 }
1266
1267 static void prepare_packed_git_one(char *objdir, int local)
1268 {
1269         struct strbuf path = STRBUF_INIT;
1270         size_t dirnamelen;
1271         DIR *dir;
1272         struct dirent *de;
1273         struct string_list garbage = STRING_LIST_INIT_DUP;
1274
1275         strbuf_addstr(&path, objdir);
1276         strbuf_addstr(&path, "/pack");
1277         dir = opendir(path.buf);
1278         if (!dir) {
1279                 if (errno != ENOENT)
1280                         error("unable to open object pack directory: %s: %s",
1281                               path.buf, strerror(errno));
1282                 strbuf_release(&path);
1283                 return;
1284         }
1285         strbuf_addch(&path, '/');
1286         dirnamelen = path.len;
1287         while ((de = readdir(dir)) != NULL) {
1288                 struct packed_git *p;
1289                 size_t base_len;
1290
1291                 if (is_dot_or_dotdot(de->d_name))
1292                         continue;
1293
1294                 strbuf_setlen(&path, dirnamelen);
1295                 strbuf_addstr(&path, de->d_name);
1296
1297                 base_len = path.len;
1298                 if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
1299                         /* Don't reopen a pack we already have. */
1300                         for (p = packed_git; p; p = p->next) {
1301                                 size_t len;
1302                                 if (strip_suffix(p->pack_name, ".pack", &len) &&
1303                                     len == base_len &&
1304                                     !memcmp(p->pack_name, path.buf, len))
1305                                         break;
1306                         }
1307                         if (p == NULL &&
1308                             /*
1309                              * See if it really is a valid .idx file with
1310                              * corresponding .pack file that we can map.
1311                              */
1312                             (p = add_packed_git(path.buf, path.len, local)) != NULL)
1313                                 install_packed_git(p);
1314                 }
1315
1316                 if (!report_garbage)
1317                         continue;
1318
1319                 if (ends_with(de->d_name, ".idx") ||
1320                     ends_with(de->d_name, ".pack") ||
1321                     ends_with(de->d_name, ".bitmap") ||
1322                     ends_with(de->d_name, ".keep"))
1323                         string_list_append(&garbage, path.buf);
1324                 else
1325                         report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
1326         }
1327         closedir(dir);
1328         report_pack_garbage(&garbage);
1329         string_list_clear(&garbage, 0);
1330         strbuf_release(&path);
1331 }
1332
1333 static int sort_pack(const void *a_, const void *b_)
1334 {
1335         struct packed_git *a = *((struct packed_git **)a_);
1336         struct packed_git *b = *((struct packed_git **)b_);
1337         int st;
1338
1339         /*
1340          * Local packs tend to contain objects specific to our
1341          * variant of the project than remote ones.  In addition,
1342          * remote ones could be on a network mounted filesystem.
1343          * Favor local ones for these reasons.
1344          */
1345         st = a->pack_local - b->pack_local;
1346         if (st)
1347                 return -st;
1348
1349         /*
1350          * Younger packs tend to contain more recent objects,
1351          * and more recent objects tend to get accessed more
1352          * often.
1353          */
1354         if (a->mtime < b->mtime)
1355                 return 1;
1356         else if (a->mtime == b->mtime)
1357                 return 0;
1358         return -1;
1359 }
1360
1361 static void rearrange_packed_git(void)
1362 {
1363         struct packed_git **ary, *p;
1364         int i, n;
1365
1366         for (n = 0, p = packed_git; p; p = p->next)
1367                 n++;
1368         if (n < 2)
1369                 return;
1370
1371         /* prepare an array of packed_git for easier sorting */
1372         ary = xcalloc(n, sizeof(struct packed_git *));
1373         for (n = 0, p = packed_git; p; p = p->next)
1374                 ary[n++] = p;
1375
1376         qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1377
1378         /* link them back again */
1379         for (i = 0; i < n - 1; i++)
1380                 ary[i]->next = ary[i + 1];
1381         ary[n - 1]->next = NULL;
1382         packed_git = ary[0];
1383
1384         free(ary);
1385 }
1386
1387 static int prepare_packed_git_run_once = 0;
1388 void prepare_packed_git(void)
1389 {
1390         struct alternate_object_database *alt;
1391
1392         if (prepare_packed_git_run_once)
1393                 return;
1394         prepare_packed_git_one(get_object_directory(), 1);
1395         prepare_alt_odb();
1396         for (alt = alt_odb_list; alt; alt = alt->next) {
1397                 alt->name[-1] = 0;
1398                 prepare_packed_git_one(alt->base, 0);
1399                 alt->name[-1] = '/';
1400         }
1401         rearrange_packed_git();
1402         prepare_packed_git_run_once = 1;
1403 }
1404
1405 void reprepare_packed_git(void)
1406 {
1407         prepare_packed_git_run_once = 0;
1408         prepare_packed_git();
1409 }
1410
1411 static void mark_bad_packed_object(struct packed_git *p,
1412                                    const unsigned char *sha1)
1413 {
1414         unsigned i;
1415         for (i = 0; i < p->num_bad_objects; i++)
1416                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1417                         return;
1418         p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1419         hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1420         p->num_bad_objects++;
1421 }
1422
1423 static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1424 {
1425         struct packed_git *p;
1426         unsigned i;
1427
1428         for (p = packed_git; p; p = p->next)
1429                 for (i = 0; i < p->num_bad_objects; i++)
1430                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1431                                 return p;
1432         return NULL;
1433 }
1434
1435 /*
1436  * With an in-core object data in "map", rehash it to make sure the
1437  * object name actually matches "sha1" to detect object corruption.
1438  * With "map" == NULL, try reading the object named with "sha1" using
1439  * the streaming interface and rehash it to do the same.
1440  */
1441 int check_sha1_signature(const unsigned char *sha1, void *map,
1442                          unsigned long size, const char *type)
1443 {
1444         unsigned char real_sha1[20];
1445         enum object_type obj_type;
1446         struct git_istream *st;
1447         git_SHA_CTX c;
1448         char hdr[32];
1449         int hdrlen;
1450
1451         if (map) {
1452                 hash_sha1_file(map, size, type, real_sha1);
1453                 return hashcmp(sha1, real_sha1) ? -1 : 0;
1454         }
1455
1456         st = open_istream(sha1, &obj_type, &size, NULL);
1457         if (!st)
1458                 return -1;
1459
1460         /* Generate the header */
1461         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(obj_type), size) + 1;
1462
1463         /* Sha1.. */
1464         git_SHA1_Init(&c);
1465         git_SHA1_Update(&c, hdr, hdrlen);
1466         for (;;) {
1467                 char buf[1024 * 16];
1468                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
1469
1470                 if (readlen < 0) {
1471                         close_istream(st);
1472                         return -1;
1473                 }
1474                 if (!readlen)
1475                         break;
1476                 git_SHA1_Update(&c, buf, readlen);
1477         }
1478         git_SHA1_Final(real_sha1, &c);
1479         close_istream(st);
1480         return hashcmp(sha1, real_sha1) ? -1 : 0;
1481 }
1482
1483 int git_open_noatime(const char *name)
1484 {
1485         static int sha1_file_open_flag = O_NOATIME;
1486
1487         for (;;) {
1488                 int fd;
1489
1490                 errno = 0;
1491                 fd = open(name, O_RDONLY | sha1_file_open_flag);
1492                 if (fd >= 0)
1493                         return fd;
1494
1495                 /* Might the failure be due to O_NOATIME? */
1496                 if (errno != ENOENT && sha1_file_open_flag) {
1497                         sha1_file_open_flag = 0;
1498                         continue;
1499                 }
1500
1501                 return -1;
1502         }
1503 }
1504
1505 static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
1506 {
1507         struct alternate_object_database *alt;
1508
1509         if (!lstat(sha1_file_name(sha1), st))
1510                 return 0;
1511
1512         prepare_alt_odb();
1513         errno = ENOENT;
1514         for (alt = alt_odb_list; alt; alt = alt->next) {
1515                 fill_sha1_path(alt->name, sha1);
1516                 if (!lstat(alt->base, st))
1517                         return 0;
1518         }
1519
1520         return -1;
1521 }
1522
1523 static int open_sha1_file(const unsigned char *sha1)
1524 {
1525         int fd;
1526         struct alternate_object_database *alt;
1527         int most_interesting_errno;
1528
1529         fd = git_open_noatime(sha1_file_name(sha1));
1530         if (fd >= 0)
1531                 return fd;
1532         most_interesting_errno = errno;
1533
1534         prepare_alt_odb();
1535         for (alt = alt_odb_list; alt; alt = alt->next) {
1536                 fill_sha1_path(alt->name, sha1);
1537                 fd = git_open_noatime(alt->base);
1538                 if (fd >= 0)
1539                         return fd;
1540                 if (most_interesting_errno == ENOENT)
1541                         most_interesting_errno = errno;
1542         }
1543         errno = most_interesting_errno;
1544         return -1;
1545 }
1546
1547 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1548 {
1549         void *map;
1550         int fd;
1551
1552         fd = open_sha1_file(sha1);
1553         map = NULL;
1554         if (fd >= 0) {
1555                 struct stat st;
1556
1557                 if (!fstat(fd, &st)) {
1558                         *size = xsize_t(st.st_size);
1559                         if (!*size) {
1560                                 /* mmap() is forbidden on empty files */
1561                                 error("object file %s is empty", sha1_file_name(sha1));
1562                                 return NULL;
1563                         }
1564                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1565                 }
1566                 close(fd);
1567         }
1568         return map;
1569 }
1570
1571 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1572                 unsigned long len, enum object_type *type, unsigned long *sizep)
1573 {
1574         unsigned shift;
1575         unsigned long size, c;
1576         unsigned long used = 0;
1577
1578         c = buf[used++];
1579         *type = (c >> 4) & 7;
1580         size = c & 15;
1581         shift = 4;
1582         while (c & 0x80) {
1583                 if (len <= used || bitsizeof(long) <= shift) {
1584                         error("bad object header");
1585                         size = used = 0;
1586                         break;
1587                 }
1588                 c = buf[used++];
1589                 size += (c & 0x7f) << shift;
1590                 shift += 7;
1591         }
1592         *sizep = size;
1593         return used;
1594 }
1595
1596 int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1597 {
1598         /* Get the data stream */
1599         memset(stream, 0, sizeof(*stream));
1600         stream->next_in = map;
1601         stream->avail_in = mapsize;
1602         stream->next_out = buffer;
1603         stream->avail_out = bufsiz;
1604
1605         git_inflate_init(stream);
1606         return git_inflate(stream, 0);
1607 }
1608
1609 static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
1610                                         unsigned long mapsize, void *buffer,
1611                                         unsigned long bufsiz, struct strbuf *header)
1612 {
1613         int status;
1614
1615         status = unpack_sha1_header(stream, map, mapsize, buffer, bufsiz);
1616
1617         /*
1618          * Check if entire header is unpacked in the first iteration.
1619          */
1620         if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1621                 return 0;
1622
1623         /*
1624          * buffer[0..bufsiz] was not large enough.  Copy the partial
1625          * result out to header, and then append the result of further
1626          * reading the stream.
1627          */
1628         strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1629         stream->next_out = buffer;
1630         stream->avail_out = bufsiz;
1631
1632         do {
1633                 status = git_inflate(stream, 0);
1634                 strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1635                 if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1636                         return 0;
1637                 stream->next_out = buffer;
1638                 stream->avail_out = bufsiz;
1639         } while (status != Z_STREAM_END);
1640         return -1;
1641 }
1642
1643 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1644 {
1645         int bytes = strlen(buffer) + 1;
1646         unsigned char *buf = xmallocz(size);
1647         unsigned long n;
1648         int status = Z_OK;
1649
1650         n = stream->total_out - bytes;
1651         if (n > size)
1652                 n = size;
1653         memcpy(buf, (char *) buffer + bytes, n);
1654         bytes = n;
1655         if (bytes <= size) {
1656                 /*
1657                  * The above condition must be (bytes <= size), not
1658                  * (bytes < size).  In other words, even though we
1659                  * expect no more output and set avail_out to zero,
1660                  * the input zlib stream may have bytes that express
1661                  * "this concludes the stream", and we *do* want to
1662                  * eat that input.
1663                  *
1664                  * Otherwise we would not be able to test that we
1665                  * consumed all the input to reach the expected size;
1666                  * we also want to check that zlib tells us that all
1667                  * went well with status == Z_STREAM_END at the end.
1668                  */
1669                 stream->next_out = buf + bytes;
1670                 stream->avail_out = size - bytes;
1671                 while (status == Z_OK)
1672                         status = git_inflate(stream, Z_FINISH);
1673         }
1674         if (status == Z_STREAM_END && !stream->avail_in) {
1675                 git_inflate_end(stream);
1676                 return buf;
1677         }
1678
1679         if (status < 0)
1680                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1681         else if (stream->avail_in)
1682                 error("garbage at end of loose object '%s'",
1683                       sha1_to_hex(sha1));
1684         free(buf);
1685         return NULL;
1686 }
1687
1688 /*
1689  * We used to just use "sscanf()", but that's actually way
1690  * too permissive for what we want to check. So do an anal
1691  * object header parse by hand.
1692  */
1693 static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1694                                unsigned int flags)
1695 {
1696         const char *type_buf = hdr;
1697         unsigned long size;
1698         int type, type_len = 0;
1699
1700         /*
1701          * The type can be of any size but is followed by
1702          * a space.
1703          */
1704         for (;;) {
1705                 char c = *hdr++;
1706                 if (c == ' ')
1707                         break;
1708                 type_len++;
1709         }
1710
1711         type = type_from_string_gently(type_buf, type_len, 1);
1712         if (oi->typename)
1713                 strbuf_add(oi->typename, type_buf, type_len);
1714         /*
1715          * Set type to 0 if its an unknown object and
1716          * we're obtaining the type using '--allow-unkown-type'
1717          * option.
1718          */
1719         if ((flags & LOOKUP_UNKNOWN_OBJECT) && (type < 0))
1720                 type = 0;
1721         else if (type < 0)
1722                 die("invalid object type");
1723         if (oi->typep)
1724                 *oi->typep = type;
1725
1726         /*
1727          * The length must follow immediately, and be in canonical
1728          * decimal format (ie "010" is not valid).
1729          */
1730         size = *hdr++ - '0';
1731         if (size > 9)
1732                 return -1;
1733         if (size) {
1734                 for (;;) {
1735                         unsigned long c = *hdr - '0';
1736                         if (c > 9)
1737                                 break;
1738                         hdr++;
1739                         size = size * 10 + c;
1740                 }
1741         }
1742
1743         if (oi->sizep)
1744                 *oi->sizep = size;
1745
1746         /*
1747          * The length must be followed by a zero byte
1748          */
1749         return *hdr ? -1 : type;
1750 }
1751
1752 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1753 {
1754         struct object_info oi;
1755
1756         oi.sizep = sizep;
1757         oi.typename = NULL;
1758         oi.typep = NULL;
1759         return parse_sha1_header_extended(hdr, &oi, LOOKUP_REPLACE_OBJECT);
1760 }
1761
1762 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1763 {
1764         int ret;
1765         git_zstream stream;
1766         char hdr[8192];
1767
1768         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1769         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1770                 return NULL;
1771
1772         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1773 }
1774
1775 unsigned long get_size_from_delta(struct packed_git *p,
1776                                   struct pack_window **w_curs,
1777                                   off_t curpos)
1778 {
1779         const unsigned char *data;
1780         unsigned char delta_head[20], *in;
1781         git_zstream stream;
1782         int st;
1783
1784         memset(&stream, 0, sizeof(stream));
1785         stream.next_out = delta_head;
1786         stream.avail_out = sizeof(delta_head);
1787
1788         git_inflate_init(&stream);
1789         do {
1790                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1791                 stream.next_in = in;
1792                 st = git_inflate(&stream, Z_FINISH);
1793                 curpos += stream.next_in - in;
1794         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1795                  stream.total_out < sizeof(delta_head));
1796         git_inflate_end(&stream);
1797         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1798                 error("delta data unpack-initial failed");
1799                 return 0;
1800         }
1801
1802         /* Examine the initial part of the delta to figure out
1803          * the result size.
1804          */
1805         data = delta_head;
1806
1807         /* ignore base size */
1808         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1809
1810         /* Read the result size */
1811         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1812 }
1813
1814 static off_t get_delta_base(struct packed_git *p,
1815                                     struct pack_window **w_curs,
1816                                     off_t *curpos,
1817                                     enum object_type type,
1818                                     off_t delta_obj_offset)
1819 {
1820         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1821         off_t base_offset;
1822
1823         /* use_pack() assured us we have [base_info, base_info + 20)
1824          * as a range that we can look at without walking off the
1825          * end of the mapped window.  Its actually the hash size
1826          * that is assured.  An OFS_DELTA longer than the hash size
1827          * is stupid, as then a REF_DELTA would be smaller to store.
1828          */
1829         if (type == OBJ_OFS_DELTA) {
1830                 unsigned used = 0;
1831                 unsigned char c = base_info[used++];
1832                 base_offset = c & 127;
1833                 while (c & 128) {
1834                         base_offset += 1;
1835                         if (!base_offset || MSB(base_offset, 7))
1836                                 return 0;  /* overflow */
1837                         c = base_info[used++];
1838                         base_offset = (base_offset << 7) + (c & 127);
1839                 }
1840                 base_offset = delta_obj_offset - base_offset;
1841                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1842                         return 0;  /* out of bound */
1843                 *curpos += used;
1844         } else if (type == OBJ_REF_DELTA) {
1845                 /* The base entry _must_ be in the same pack */
1846                 base_offset = find_pack_entry_one(base_info, p);
1847                 *curpos += 20;
1848         } else
1849                 die("I am totally screwed");
1850         return base_offset;
1851 }
1852
1853 /*
1854  * Like get_delta_base above, but we return the sha1 instead of the pack
1855  * offset. This means it is cheaper for REF deltas (we do not have to do
1856  * the final object lookup), but more expensive for OFS deltas (we
1857  * have to load the revidx to convert the offset back into a sha1).
1858  */
1859 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1860                                                 struct pack_window **w_curs,
1861                                                 off_t curpos,
1862                                                 enum object_type type,
1863                                                 off_t delta_obj_offset)
1864 {
1865         if (type == OBJ_REF_DELTA) {
1866                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1867                 return base;
1868         } else if (type == OBJ_OFS_DELTA) {
1869                 struct revindex_entry *revidx;
1870                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1871                                                    type, delta_obj_offset);
1872
1873                 if (!base_offset)
1874                         return NULL;
1875
1876                 revidx = find_pack_revindex(p, base_offset);
1877                 if (!revidx)
1878                         return NULL;
1879
1880                 return nth_packed_object_sha1(p, revidx->nr);
1881         } else
1882                 return NULL;
1883 }
1884
1885 int unpack_object_header(struct packed_git *p,
1886                          struct pack_window **w_curs,
1887                          off_t *curpos,
1888                          unsigned long *sizep)
1889 {
1890         unsigned char *base;
1891         unsigned long left;
1892         unsigned long used;
1893         enum object_type type;
1894
1895         /* use_pack() assures us we have [base, base + 20) available
1896          * as a range that we can look at.  (Its actually the hash
1897          * size that is assured.)  With our object header encoding
1898          * the maximum deflated object size is 2^137, which is just
1899          * insane, so we know won't exceed what we have been given.
1900          */
1901         base = use_pack(p, w_curs, *curpos, &left);
1902         used = unpack_object_header_buffer(base, left, &type, sizep);
1903         if (!used) {
1904                 type = OBJ_BAD;
1905         } else
1906                 *curpos += used;
1907
1908         return type;
1909 }
1910
1911 static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1912 {
1913         int type;
1914         struct revindex_entry *revidx;
1915         const unsigned char *sha1;
1916         revidx = find_pack_revindex(p, obj_offset);
1917         if (!revidx)
1918                 return OBJ_BAD;
1919         sha1 = nth_packed_object_sha1(p, revidx->nr);
1920         mark_bad_packed_object(p, sha1);
1921         type = sha1_object_info(sha1, NULL);
1922         if (type <= OBJ_NONE)
1923                 return OBJ_BAD;
1924         return type;
1925 }
1926
1927 #define POI_STACK_PREALLOC 64
1928
1929 static enum object_type packed_to_object_type(struct packed_git *p,
1930                                               off_t obj_offset,
1931                                               enum object_type type,
1932                                               struct pack_window **w_curs,
1933                                               off_t curpos)
1934 {
1935         off_t small_poi_stack[POI_STACK_PREALLOC];
1936         off_t *poi_stack = small_poi_stack;
1937         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1938
1939         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1940                 off_t base_offset;
1941                 unsigned long size;
1942                 /* Push the object we're going to leave behind */
1943                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1944                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1945                         poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
1946                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1947                 } else {
1948                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1949                 }
1950                 poi_stack[poi_stack_nr++] = obj_offset;
1951                 /* If parsing the base offset fails, just unwind */
1952                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1953                 if (!base_offset)
1954                         goto unwind;
1955                 curpos = obj_offset = base_offset;
1956                 type = unpack_object_header(p, w_curs, &curpos, &size);
1957                 if (type <= OBJ_NONE) {
1958                         /* If getting the base itself fails, we first
1959                          * retry the base, otherwise unwind */
1960                         type = retry_bad_packed_offset(p, base_offset);
1961                         if (type > OBJ_NONE)
1962                                 goto out;
1963                         goto unwind;
1964                 }
1965         }
1966
1967         switch (type) {
1968         case OBJ_BAD:
1969         case OBJ_COMMIT:
1970         case OBJ_TREE:
1971         case OBJ_BLOB:
1972         case OBJ_TAG:
1973                 break;
1974         default:
1975                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1976                       type, (uintmax_t)obj_offset, p->pack_name);
1977                 type = OBJ_BAD;
1978         }
1979
1980 out:
1981         if (poi_stack != small_poi_stack)
1982                 free(poi_stack);
1983         return type;
1984
1985 unwind:
1986         while (poi_stack_nr) {
1987                 obj_offset = poi_stack[--poi_stack_nr];
1988                 type = retry_bad_packed_offset(p, obj_offset);
1989                 if (type > OBJ_NONE)
1990                         goto out;
1991         }
1992         type = OBJ_BAD;
1993         goto out;
1994 }
1995
1996 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1997                               struct object_info *oi)
1998 {
1999         struct pack_window *w_curs = NULL;
2000         unsigned long size;
2001         off_t curpos = obj_offset;
2002         enum object_type type;
2003
2004         /*
2005          * We always get the representation type, but only convert it to
2006          * a "real" type later if the caller is interested.
2007          */
2008         type = unpack_object_header(p, &w_curs, &curpos, &size);
2009
2010         if (oi->sizep) {
2011                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
2012                         off_t tmp_pos = curpos;
2013                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
2014                                                            type, obj_offset);
2015                         if (!base_offset) {
2016                                 type = OBJ_BAD;
2017                                 goto out;
2018                         }
2019                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
2020                         if (*oi->sizep == 0) {
2021                                 type = OBJ_BAD;
2022                                 goto out;
2023                         }
2024                 } else {
2025                         *oi->sizep = size;
2026                 }
2027         }
2028
2029         if (oi->disk_sizep) {
2030                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2031                 *oi->disk_sizep = revidx[1].offset - obj_offset;
2032         }
2033
2034         if (oi->typep) {
2035                 *oi->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
2036                 if (*oi->typep < 0) {
2037                         type = OBJ_BAD;
2038                         goto out;
2039                 }
2040         }
2041
2042         if (oi->delta_base_sha1) {
2043                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
2044                         const unsigned char *base;
2045
2046                         base = get_delta_base_sha1(p, &w_curs, curpos,
2047                                                    type, obj_offset);
2048                         if (!base) {
2049                                 type = OBJ_BAD;
2050                                 goto out;
2051                         }
2052
2053                         hashcpy(oi->delta_base_sha1, base);
2054                 } else
2055                         hashclr(oi->delta_base_sha1);
2056         }
2057
2058 out:
2059         unuse_pack(&w_curs);
2060         return type;
2061 }
2062
2063 static void *unpack_compressed_entry(struct packed_git *p,
2064                                     struct pack_window **w_curs,
2065                                     off_t curpos,
2066                                     unsigned long size)
2067 {
2068         int st;
2069         git_zstream stream;
2070         unsigned char *buffer, *in;
2071
2072         buffer = xmallocz_gently(size);
2073         if (!buffer)
2074                 return NULL;
2075         memset(&stream, 0, sizeof(stream));
2076         stream.next_out = buffer;
2077         stream.avail_out = size + 1;
2078
2079         git_inflate_init(&stream);
2080         do {
2081                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
2082                 stream.next_in = in;
2083                 st = git_inflate(&stream, Z_FINISH);
2084                 if (!stream.avail_out)
2085                         break; /* the payload is larger than it should be */
2086                 curpos += stream.next_in - in;
2087         } while (st == Z_OK || st == Z_BUF_ERROR);
2088         git_inflate_end(&stream);
2089         if ((st != Z_STREAM_END) || stream.total_out != size) {
2090                 free(buffer);
2091                 return NULL;
2092         }
2093
2094         return buffer;
2095 }
2096
2097 #define MAX_DELTA_CACHE (256)
2098
2099 static size_t delta_base_cached;
2100
2101 static struct delta_base_cache_lru_list {
2102         struct delta_base_cache_lru_list *prev;
2103         struct delta_base_cache_lru_list *next;
2104 } delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
2105
2106 static struct delta_base_cache_entry {
2107         struct delta_base_cache_lru_list lru;
2108         void *data;
2109         struct packed_git *p;
2110         off_t base_offset;
2111         unsigned long size;
2112         enum object_type type;
2113 } delta_base_cache[MAX_DELTA_CACHE];
2114
2115 static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
2116 {
2117         unsigned long hash;
2118
2119         hash = (unsigned long)(intptr_t)p + (unsigned long)base_offset;
2120         hash += (hash >> 8) + (hash >> 16);
2121         return hash % MAX_DELTA_CACHE;
2122 }
2123
2124 static struct delta_base_cache_entry *
2125 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
2126 {
2127         unsigned long hash = pack_entry_hash(p, base_offset);
2128         return delta_base_cache + hash;
2129 }
2130
2131 static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
2132                                      struct packed_git *p, off_t base_offset)
2133 {
2134         return (ent->data && ent->p == p && ent->base_offset == base_offset);
2135 }
2136
2137 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
2138 {
2139         struct delta_base_cache_entry *ent;
2140         ent = get_delta_base_cache_entry(p, base_offset);
2141         return eq_delta_base_cache_entry(ent, p, base_offset);
2142 }
2143
2144 static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
2145 {
2146         ent->data = NULL;
2147         ent->lru.next->prev = ent->lru.prev;
2148         ent->lru.prev->next = ent->lru.next;
2149         delta_base_cached -= ent->size;
2150 }
2151
2152 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
2153         unsigned long *base_size, enum object_type *type, int keep_cache)
2154 {
2155         struct delta_base_cache_entry *ent;
2156         void *ret;
2157
2158         ent = get_delta_base_cache_entry(p, base_offset);
2159
2160         if (!eq_delta_base_cache_entry(ent, p, base_offset))
2161                 return unpack_entry(p, base_offset, type, base_size);
2162
2163         ret = ent->data;
2164
2165         if (!keep_cache)
2166                 clear_delta_base_cache_entry(ent);
2167         else
2168                 ret = xmemdupz(ent->data, ent->size);
2169         *type = ent->type;
2170         *base_size = ent->size;
2171         return ret;
2172 }
2173
2174 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
2175 {
2176         if (ent->data) {
2177                 free(ent->data);
2178                 ent->data = NULL;
2179                 ent->lru.next->prev = ent->lru.prev;
2180                 ent->lru.prev->next = ent->lru.next;
2181                 delta_base_cached -= ent->size;
2182         }
2183 }
2184
2185 void clear_delta_base_cache(void)
2186 {
2187         unsigned long p;
2188         for (p = 0; p < MAX_DELTA_CACHE; p++)
2189                 release_delta_base_cache(&delta_base_cache[p]);
2190 }
2191
2192 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
2193         void *base, unsigned long base_size, enum object_type type)
2194 {
2195         unsigned long hash = pack_entry_hash(p, base_offset);
2196         struct delta_base_cache_entry *ent = delta_base_cache + hash;
2197         struct delta_base_cache_lru_list *lru;
2198
2199         release_delta_base_cache(ent);
2200         delta_base_cached += base_size;
2201
2202         for (lru = delta_base_cache_lru.next;
2203              delta_base_cached > delta_base_cache_limit
2204              && lru != &delta_base_cache_lru;
2205              lru = lru->next) {
2206                 struct delta_base_cache_entry *f = (void *)lru;
2207                 if (f->type == OBJ_BLOB)
2208                         release_delta_base_cache(f);
2209         }
2210         for (lru = delta_base_cache_lru.next;
2211              delta_base_cached > delta_base_cache_limit
2212              && lru != &delta_base_cache_lru;
2213              lru = lru->next) {
2214                 struct delta_base_cache_entry *f = (void *)lru;
2215                 release_delta_base_cache(f);
2216         }
2217
2218         ent->p = p;
2219         ent->base_offset = base_offset;
2220         ent->type = type;
2221         ent->data = base;
2222         ent->size = base_size;
2223         ent->lru.next = &delta_base_cache_lru;
2224         ent->lru.prev = delta_base_cache_lru.prev;
2225         delta_base_cache_lru.prev->next = &ent->lru;
2226         delta_base_cache_lru.prev = &ent->lru;
2227 }
2228
2229 static void *read_object(const unsigned char *sha1, enum object_type *type,
2230                          unsigned long *size);
2231
2232 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
2233 {
2234         static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
2235         trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
2236                          p->pack_name, (uintmax_t)obj_offset);
2237 }
2238
2239 int do_check_packed_object_crc;
2240
2241 #define UNPACK_ENTRY_STACK_PREALLOC 64
2242 struct unpack_entry_stack_ent {
2243         off_t obj_offset;
2244         off_t curpos;
2245         unsigned long size;
2246 };
2247
2248 void *unpack_entry(struct packed_git *p, off_t obj_offset,
2249                    enum object_type *final_type, unsigned long *final_size)
2250 {
2251         struct pack_window *w_curs = NULL;
2252         off_t curpos = obj_offset;
2253         void *data = NULL;
2254         unsigned long size;
2255         enum object_type type;
2256         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2257         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2258         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2259         int base_from_cache = 0;
2260
2261         write_pack_access_log(p, obj_offset);
2262
2263         /* PHASE 1: drill down to the innermost base object */
2264         for (;;) {
2265                 off_t base_offset;
2266                 int i;
2267                 struct delta_base_cache_entry *ent;
2268
2269                 ent = get_delta_base_cache_entry(p, curpos);
2270                 if (eq_delta_base_cache_entry(ent, p, curpos)) {
2271                         type = ent->type;
2272                         data = ent->data;
2273                         size = ent->size;
2274                         clear_delta_base_cache_entry(ent);
2275                         base_from_cache = 1;
2276                         break;
2277                 }
2278
2279                 if (do_check_packed_object_crc && p->index_version > 1) {
2280                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2281                         unsigned long len = revidx[1].offset - obj_offset;
2282                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2283                                 const unsigned char *sha1 =
2284                                         nth_packed_object_sha1(p, revidx->nr);
2285                                 error("bad packed object CRC for %s",
2286                                       sha1_to_hex(sha1));
2287                                 mark_bad_packed_object(p, sha1);
2288                                 unuse_pack(&w_curs);
2289                                 return NULL;
2290                         }
2291                 }
2292
2293                 type = unpack_object_header(p, &w_curs, &curpos, &size);
2294                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2295                         break;
2296
2297                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2298                 if (!base_offset) {
2299                         error("failed to validate delta base reference "
2300                               "at offset %"PRIuMAX" from %s",
2301                               (uintmax_t)curpos, p->pack_name);
2302                         /* bail to phase 2, in hopes of recovery */
2303                         data = NULL;
2304                         break;
2305                 }
2306
2307                 /* push object, proceed to base */
2308                 if (delta_stack_nr >= delta_stack_alloc
2309                     && delta_stack == small_delta_stack) {
2310                         delta_stack_alloc = alloc_nr(delta_stack_nr);
2311                         delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
2312                         memcpy(delta_stack, small_delta_stack,
2313                                sizeof(*delta_stack)*delta_stack_nr);
2314                 } else {
2315                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2316                 }
2317                 i = delta_stack_nr++;
2318                 delta_stack[i].obj_offset = obj_offset;
2319                 delta_stack[i].curpos = curpos;
2320                 delta_stack[i].size = size;
2321
2322                 curpos = obj_offset = base_offset;
2323         }
2324
2325         /* PHASE 2: handle the base */
2326         switch (type) {
2327         case OBJ_OFS_DELTA:
2328         case OBJ_REF_DELTA:
2329                 if (data)
2330                         die("BUG in unpack_entry: left loop at a valid delta");
2331                 break;
2332         case OBJ_COMMIT:
2333         case OBJ_TREE:
2334         case OBJ_BLOB:
2335         case OBJ_TAG:
2336                 if (!base_from_cache)
2337                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
2338                 break;
2339         default:
2340                 data = NULL;
2341                 error("unknown object type %i at offset %"PRIuMAX" in %s",
2342                       type, (uintmax_t)obj_offset, p->pack_name);
2343         }
2344
2345         /* PHASE 3: apply deltas in order */
2346
2347         /* invariants:
2348          *   'data' holds the base data, or NULL if there was corruption
2349          */
2350         while (delta_stack_nr) {
2351                 void *delta_data;
2352                 void *base = data;
2353                 unsigned long delta_size, base_size = size;
2354                 int i;
2355
2356                 data = NULL;
2357
2358                 if (base)
2359                         add_delta_base_cache(p, obj_offset, base, base_size, type);
2360
2361                 if (!base) {
2362                         /*
2363                          * We're probably in deep shit, but let's try to fetch
2364                          * the required base anyway from another pack or loose.
2365                          * This is costly but should happen only in the presence
2366                          * of a corrupted pack, and is better than failing outright.
2367                          */
2368                         struct revindex_entry *revidx;
2369                         const unsigned char *base_sha1;
2370                         revidx = find_pack_revindex(p, obj_offset);
2371                         if (revidx) {
2372                                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2373                                 error("failed to read delta base object %s"
2374                                       " at offset %"PRIuMAX" from %s",
2375                                       sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2376                                       p->pack_name);
2377                                 mark_bad_packed_object(p, base_sha1);
2378                                 base = read_object(base_sha1, &type, &base_size);
2379                         }
2380                 }
2381
2382                 i = --delta_stack_nr;
2383                 obj_offset = delta_stack[i].obj_offset;
2384                 curpos = delta_stack[i].curpos;
2385                 delta_size = delta_stack[i].size;
2386
2387                 if (!base)
2388                         continue;
2389
2390                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2391
2392                 if (!delta_data) {
2393                         error("failed to unpack compressed delta "
2394                               "at offset %"PRIuMAX" from %s",
2395                               (uintmax_t)curpos, p->pack_name);
2396                         data = NULL;
2397                         continue;
2398                 }
2399
2400                 data = patch_delta(base, base_size,
2401                                    delta_data, delta_size,
2402                                    &size);
2403
2404                 /*
2405                  * We could not apply the delta; warn the user, but keep going.
2406                  * Our failure will be noticed either in the next iteration of
2407                  * the loop, or if this is the final delta, in the caller when
2408                  * we return NULL. Those code paths will take care of making
2409                  * a more explicit warning and retrying with another copy of
2410                  * the object.
2411                  */
2412                 if (!data)
2413                         error("failed to apply delta");
2414
2415                 free(delta_data);
2416         }
2417
2418         *final_type = type;
2419         *final_size = size;
2420
2421         unuse_pack(&w_curs);
2422
2423         if (delta_stack != small_delta_stack)
2424                 free(delta_stack);
2425
2426         return data;
2427 }
2428
2429 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2430                                             uint32_t n)
2431 {
2432         const unsigned char *index = p->index_data;
2433         if (!index) {
2434                 if (open_pack_index(p))
2435                         return NULL;
2436                 index = p->index_data;
2437         }
2438         if (n >= p->num_objects)
2439                 return NULL;
2440         index += 4 * 256;
2441         if (p->index_version == 1) {
2442                 return index + 24 * n + 4;
2443         } else {
2444                 index += 8;
2445                 return index + 20 * n;
2446         }
2447 }
2448
2449 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2450 {
2451         const unsigned char *index = p->index_data;
2452         index += 4 * 256;
2453         if (p->index_version == 1) {
2454                 return ntohl(*((uint32_t *)(index + 24 * n)));
2455         } else {
2456                 uint32_t off;
2457                 index += 8 + p->num_objects * (20 + 4);
2458                 off = ntohl(*((uint32_t *)(index + 4 * n)));
2459                 if (!(off & 0x80000000))
2460                         return off;
2461                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2462                 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2463                                    ntohl(*((uint32_t *)(index + 4)));
2464         }
2465 }
2466
2467 off_t find_pack_entry_one(const unsigned char *sha1,
2468                                   struct packed_git *p)
2469 {
2470         const uint32_t *level1_ofs = p->index_data;
2471         const unsigned char *index = p->index_data;
2472         unsigned hi, lo, stride;
2473         static int use_lookup = -1;
2474         static int debug_lookup = -1;
2475
2476         if (debug_lookup < 0)
2477                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2478
2479         if (!index) {
2480                 if (open_pack_index(p))
2481                         return 0;
2482                 level1_ofs = p->index_data;
2483                 index = p->index_data;
2484         }
2485         if (p->index_version > 1) {
2486                 level1_ofs += 2;
2487                 index += 8;
2488         }
2489         index += 4 * 256;
2490         hi = ntohl(level1_ofs[*sha1]);
2491         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2492         if (p->index_version > 1) {
2493                 stride = 20;
2494         } else {
2495                 stride = 24;
2496                 index += 4;
2497         }
2498
2499         if (debug_lookup)
2500                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2501                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2502
2503         if (use_lookup < 0)
2504                 use_lookup = !!getenv("GIT_USE_LOOKUP");
2505         if (use_lookup) {
2506                 int pos = sha1_entry_pos(index, stride, 0,
2507                                          lo, hi, p->num_objects, sha1);
2508                 if (pos < 0)
2509                         return 0;
2510                 return nth_packed_object_offset(p, pos);
2511         }
2512
2513         do {
2514                 unsigned mi = (lo + hi) / 2;
2515                 int cmp = hashcmp(index + mi * stride, sha1);
2516
2517                 if (debug_lookup)
2518                         printf("lo %u hi %u rg %u mi %u\n",
2519                                lo, hi, hi - lo, mi);
2520                 if (!cmp)
2521                         return nth_packed_object_offset(p, mi);
2522                 if (cmp > 0)
2523                         hi = mi;
2524                 else
2525                         lo = mi+1;
2526         } while (lo < hi);
2527         return 0;
2528 }
2529
2530 int is_pack_valid(struct packed_git *p)
2531 {
2532         /* An already open pack is known to be valid. */
2533         if (p->pack_fd != -1)
2534                 return 1;
2535
2536         /* If the pack has one window completely covering the
2537          * file size, the pack is known to be valid even if
2538          * the descriptor is not currently open.
2539          */
2540         if (p->windows) {
2541                 struct pack_window *w = p->windows;
2542
2543                 if (!w->offset && w->len == p->pack_size)
2544                         return 1;
2545         }
2546
2547         /* Force the pack to open to prove its valid. */
2548         return !open_packed_git(p);
2549 }
2550
2551 static int fill_pack_entry(const unsigned char *sha1,
2552                            struct pack_entry *e,
2553                            struct packed_git *p)
2554 {
2555         off_t offset;
2556
2557         if (p->num_bad_objects) {
2558                 unsigned i;
2559                 for (i = 0; i < p->num_bad_objects; i++)
2560                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2561                                 return 0;
2562         }
2563
2564         offset = find_pack_entry_one(sha1, p);
2565         if (!offset)
2566                 return 0;
2567
2568         /*
2569          * We are about to tell the caller where they can locate the
2570          * requested object.  We better make sure the packfile is
2571          * still here and can be accessed before supplying that
2572          * answer, as it may have been deleted since the index was
2573          * loaded!
2574          */
2575         if (!is_pack_valid(p))
2576                 return 0;
2577         e->offset = offset;
2578         e->p = p;
2579         hashcpy(e->sha1, sha1);
2580         return 1;
2581 }
2582
2583 /*
2584  * Iff a pack file contains the object named by sha1, return true and
2585  * store its location to e.
2586  */
2587 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2588 {
2589         struct packed_git *p;
2590
2591         prepare_packed_git();
2592         if (!packed_git)
2593                 return 0;
2594
2595         if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2596                 return 1;
2597
2598         for (p = packed_git; p; p = p->next) {
2599                 if (p == last_found_pack)
2600                         continue; /* we already checked this one */
2601
2602                 if (fill_pack_entry(sha1, e, p)) {
2603                         last_found_pack = p;
2604                         return 1;
2605                 }
2606         }
2607         return 0;
2608 }
2609
2610 struct packed_git *find_sha1_pack(const unsigned char *sha1,
2611                                   struct packed_git *packs)
2612 {
2613         struct packed_git *p;
2614
2615         for (p = packs; p; p = p->next) {
2616                 if (find_pack_entry_one(sha1, p))
2617                         return p;
2618         }
2619         return NULL;
2620
2621 }
2622
2623 static int sha1_loose_object_info(const unsigned char *sha1,
2624                                   struct object_info *oi,
2625                                   int flags)
2626 {
2627         int status = 0;
2628         unsigned long mapsize;
2629         void *map;
2630         git_zstream stream;
2631         char hdr[32];
2632         struct strbuf hdrbuf = STRBUF_INIT;
2633
2634         if (oi->delta_base_sha1)
2635                 hashclr(oi->delta_base_sha1);
2636
2637         /*
2638          * If we don't care about type or size, then we don't
2639          * need to look inside the object at all. Note that we
2640          * do not optimize out the stat call, even if the
2641          * caller doesn't care about the disk-size, since our
2642          * return value implicitly indicates whether the
2643          * object even exists.
2644          */
2645         if (!oi->typep && !oi->typename && !oi->sizep) {
2646                 struct stat st;
2647                 if (stat_sha1_file(sha1, &st) < 0)
2648                         return -1;
2649                 if (oi->disk_sizep)
2650                         *oi->disk_sizep = st.st_size;
2651                 return 0;
2652         }
2653
2654         map = map_sha1_file(sha1, &mapsize);
2655         if (!map)
2656                 return -1;
2657         if (oi->disk_sizep)
2658                 *oi->disk_sizep = mapsize;
2659         if ((flags & LOOKUP_UNKNOWN_OBJECT)) {
2660                 if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
2661                         status = error("unable to unpack %s header with --allow-unknown-type",
2662                                        sha1_to_hex(sha1));
2663         } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2664                 status = error("unable to unpack %s header",
2665                                sha1_to_hex(sha1));
2666         if (status < 0)
2667                 ; /* Do nothing */
2668         else if (hdrbuf.len) {
2669                 if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
2670                         status = error("unable to parse %s header with --allow-unknown-type",
2671                                        sha1_to_hex(sha1));
2672         } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
2673                 status = error("unable to parse %s header", sha1_to_hex(sha1));
2674         git_inflate_end(&stream);
2675         munmap(map, mapsize);
2676         if (status && oi->typep)
2677                 *oi->typep = status;
2678         strbuf_release(&hdrbuf);
2679         return 0;
2680 }
2681
2682 int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
2683 {
2684         struct cached_object *co;
2685         struct pack_entry e;
2686         int rtype;
2687         enum object_type real_type;
2688         const unsigned char *real = lookup_replace_object_extended(sha1, flags);
2689
2690         co = find_cached_object(real);
2691         if (co) {
2692                 if (oi->typep)
2693                         *(oi->typep) = co->type;
2694                 if (oi->sizep)
2695                         *(oi->sizep) = co->size;
2696                 if (oi->disk_sizep)
2697                         *(oi->disk_sizep) = 0;
2698                 if (oi->delta_base_sha1)
2699                         hashclr(oi->delta_base_sha1);
2700                 if (oi->typename)
2701                         strbuf_addstr(oi->typename, typename(co->type));
2702                 oi->whence = OI_CACHED;
2703                 return 0;
2704         }
2705
2706         if (!find_pack_entry(real, &e)) {
2707                 /* Most likely it's a loose object. */
2708                 if (!sha1_loose_object_info(real, oi, flags)) {
2709                         oi->whence = OI_LOOSE;
2710                         return 0;
2711                 }
2712
2713                 /* Not a loose object; someone else may have just packed it. */
2714                 reprepare_packed_git();
2715                 if (!find_pack_entry(real, &e))
2716                         return -1;
2717         }
2718
2719         /*
2720          * packed_object_info() does not follow the delta chain to
2721          * find out the real type, unless it is given oi->typep.
2722          */
2723         if (oi->typename && !oi->typep)
2724                 oi->typep = &real_type;
2725
2726         rtype = packed_object_info(e.p, e.offset, oi);
2727         if (rtype < 0) {
2728                 mark_bad_packed_object(e.p, real);
2729                 if (oi->typep == &real_type)
2730                         oi->typep = NULL;
2731                 return sha1_object_info_extended(real, oi, 0);
2732         } else if (in_delta_base_cache(e.p, e.offset)) {
2733                 oi->whence = OI_DBCACHED;
2734         } else {
2735                 oi->whence = OI_PACKED;
2736                 oi->u.packed.offset = e.offset;
2737                 oi->u.packed.pack = e.p;
2738                 oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2739                                          rtype == OBJ_OFS_DELTA);
2740         }
2741         if (oi->typename)
2742                 strbuf_addstr(oi->typename, typename(*oi->typep));
2743         if (oi->typep == &real_type)
2744                 oi->typep = NULL;
2745
2746         return 0;
2747 }
2748
2749 /* returns enum object_type or negative */
2750 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2751 {
2752         enum object_type type;
2753         struct object_info oi = {NULL};
2754
2755         oi.typep = &type;
2756         oi.sizep = sizep;
2757         if (sha1_object_info_extended(sha1, &oi, LOOKUP_REPLACE_OBJECT) < 0)
2758                 return -1;
2759         return type;
2760 }
2761
2762 static void *read_packed_sha1(const unsigned char *sha1,
2763                               enum object_type *type, unsigned long *size)
2764 {
2765         struct pack_entry e;
2766         void *data;
2767
2768         if (!find_pack_entry(sha1, &e))
2769                 return NULL;
2770         data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2771         if (!data) {
2772                 /*
2773                  * We're probably in deep shit, but let's try to fetch
2774                  * the required object anyway from another pack or loose.
2775                  * This should happen only in the presence of a corrupted
2776                  * pack, and is better than failing outright.
2777                  */
2778                 error("failed to read object %s at offset %"PRIuMAX" from %s",
2779                       sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2780                 mark_bad_packed_object(e.p, sha1);
2781                 data = read_object(sha1, type, size);
2782         }
2783         return data;
2784 }
2785
2786 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2787                       unsigned char *sha1)
2788 {
2789         struct cached_object *co;
2790
2791         hash_sha1_file(buf, len, typename(type), sha1);
2792         if (has_sha1_file(sha1) || find_cached_object(sha1))
2793                 return 0;
2794         ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
2795         co = &cached_objects[cached_object_nr++];
2796         co->size = len;
2797         co->type = type;
2798         co->buf = xmalloc(len);
2799         memcpy(co->buf, buf, len);
2800         hashcpy(co->sha1, sha1);
2801         return 0;
2802 }
2803
2804 static void *read_object(const unsigned char *sha1, enum object_type *type,
2805                          unsigned long *size)
2806 {
2807         unsigned long mapsize;
2808         void *map, *buf;
2809         struct cached_object *co;
2810
2811         co = find_cached_object(sha1);
2812         if (co) {
2813                 *type = co->type;
2814                 *size = co->size;
2815                 return xmemdupz(co->buf, co->size);
2816         }
2817
2818         buf = read_packed_sha1(sha1, type, size);
2819         if (buf)
2820                 return buf;
2821         map = map_sha1_file(sha1, &mapsize);
2822         if (map) {
2823                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2824                 munmap(map, mapsize);
2825                 return buf;
2826         }
2827         reprepare_packed_git();
2828         return read_packed_sha1(sha1, type, size);
2829 }
2830
2831 /*
2832  * This function dies on corrupt objects; the callers who want to
2833  * deal with them should arrange to call read_object() and give error
2834  * messages themselves.
2835  */
2836 void *read_sha1_file_extended(const unsigned char *sha1,
2837                               enum object_type *type,
2838                               unsigned long *size,
2839                               unsigned flag)
2840 {
2841         void *data;
2842         const struct packed_git *p;
2843         const unsigned char *repl = lookup_replace_object_extended(sha1, flag);
2844
2845         errno = 0;
2846         data = read_object(repl, type, size);
2847         if (data)
2848                 return data;
2849
2850         if (errno && errno != ENOENT)
2851                 die_errno("failed to read object %s", sha1_to_hex(sha1));
2852
2853         /* die if we replaced an object with one that does not exist */
2854         if (repl != sha1)
2855                 die("replacement %s not found for %s",
2856                     sha1_to_hex(repl), sha1_to_hex(sha1));
2857
2858         if (has_loose_object(repl)) {
2859                 const char *path = sha1_file_name(sha1);
2860
2861                 die("loose object %s (stored in %s) is corrupt",
2862                     sha1_to_hex(repl), path);
2863         }
2864
2865         if ((p = has_packed_and_bad(repl)) != NULL)
2866                 die("packed object %s (stored in %s) is corrupt",
2867                     sha1_to_hex(repl), p->pack_name);
2868
2869         return NULL;
2870 }
2871
2872 void *read_object_with_reference(const unsigned char *sha1,
2873                                  const char *required_type_name,
2874                                  unsigned long *size,
2875                                  unsigned char *actual_sha1_return)
2876 {
2877         enum object_type type, required_type;
2878         void *buffer;
2879         unsigned long isize;
2880         unsigned char actual_sha1[20];
2881
2882         required_type = type_from_string(required_type_name);
2883         hashcpy(actual_sha1, sha1);
2884         while (1) {
2885                 int ref_length = -1;
2886                 const char *ref_type = NULL;
2887
2888                 buffer = read_sha1_file(actual_sha1, &type, &isize);
2889                 if (!buffer)
2890                         return NULL;
2891                 if (type == required_type) {
2892                         *size = isize;
2893                         if (actual_sha1_return)
2894                                 hashcpy(actual_sha1_return, actual_sha1);
2895                         return buffer;
2896                 }
2897                 /* Handle references */
2898                 else if (type == OBJ_COMMIT)
2899                         ref_type = "tree ";
2900                 else if (type == OBJ_TAG)
2901                         ref_type = "object ";
2902                 else {
2903                         free(buffer);
2904                         return NULL;
2905                 }
2906                 ref_length = strlen(ref_type);
2907
2908                 if (ref_length + 40 > isize ||
2909                     memcmp(buffer, ref_type, ref_length) ||
2910                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2911                         free(buffer);
2912                         return NULL;
2913                 }
2914                 free(buffer);
2915                 /* Now we have the ID of the referred-to object in
2916                  * actual_sha1.  Check again. */
2917         }
2918 }
2919
2920 static void write_sha1_file_prepare(const void *buf, unsigned long len,
2921                                     const char *type, unsigned char *sha1,
2922                                     char *hdr, int *hdrlen)
2923 {
2924         git_SHA_CTX c;
2925
2926         /* Generate the header */
2927         *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
2928
2929         /* Sha1.. */
2930         git_SHA1_Init(&c);
2931         git_SHA1_Update(&c, hdr, *hdrlen);
2932         git_SHA1_Update(&c, buf, len);
2933         git_SHA1_Final(sha1, &c);
2934 }
2935
2936 /*
2937  * Move the just written object into its final resting place.
2938  */
2939 int finalize_object_file(const char *tmpfile, const char *filename)
2940 {
2941         int ret = 0;
2942
2943         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2944                 goto try_rename;
2945         else if (link(tmpfile, filename))
2946                 ret = errno;
2947
2948         /*
2949          * Coda hack - coda doesn't like cross-directory links,
2950          * so we fall back to a rename, which will mean that it
2951          * won't be able to check collisions, but that's not a
2952          * big deal.
2953          *
2954          * The same holds for FAT formatted media.
2955          *
2956          * When this succeeds, we just return.  We have nothing
2957          * left to unlink.
2958          */
2959         if (ret && ret != EEXIST) {
2960         try_rename:
2961                 if (!rename(tmpfile, filename))
2962                         goto out;
2963                 ret = errno;
2964         }
2965         unlink_or_warn(tmpfile);
2966         if (ret) {
2967                 if (ret != EEXIST) {
2968                         return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
2969                 }
2970                 /* FIXME!!! Collision check here ? */
2971         }
2972
2973 out:
2974         if (adjust_shared_perm(filename))
2975                 return error("unable to set permission to '%s'", filename);
2976         return 0;
2977 }
2978
2979 static int write_buffer(int fd, const void *buf, size_t len)
2980 {
2981         if (write_in_full(fd, buf, len) < 0)
2982                 return error("file write error (%s)", strerror(errno));
2983         return 0;
2984 }
2985
2986 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2987                    unsigned char *sha1)
2988 {
2989         char hdr[32];
2990         int hdrlen = sizeof(hdr);
2991         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2992         return 0;
2993 }
2994
2995 /* Finalize a file on disk, and close it. */
2996 static void close_sha1_file(int fd)
2997 {
2998         if (fsync_object_files)
2999                 fsync_or_die(fd, "sha1 file");
3000         if (close(fd) != 0)
3001                 die_errno("error when closing sha1 file");
3002 }
3003
3004 /* Size of directory component, including the ending '/' */
3005 static inline int directory_size(const char *filename)
3006 {
3007         const char *s = strrchr(filename, '/');
3008         if (!s)
3009                 return 0;
3010         return s - filename + 1;
3011 }
3012
3013 /*
3014  * This creates a temporary file in the same directory as the final
3015  * 'filename'
3016  *
3017  * We want to avoid cross-directory filename renames, because those
3018  * can have problems on various filesystems (FAT, NFS, Coda).
3019  */
3020 static int create_tmpfile(struct strbuf *tmp, const char *filename)
3021 {
3022         int fd, dirlen = directory_size(filename);
3023
3024         strbuf_reset(tmp);
3025         strbuf_add(tmp, filename, dirlen);
3026         strbuf_addstr(tmp, "tmp_obj_XXXXXX");
3027         fd = git_mkstemp_mode(tmp->buf, 0444);
3028         if (fd < 0 && dirlen && errno == ENOENT) {
3029                 /*
3030                  * Make sure the directory exists; note that the contents
3031                  * of the buffer are undefined after mkstemp returns an
3032                  * error, so we have to rewrite the whole buffer from
3033                  * scratch.
3034                  */
3035                 strbuf_reset(tmp);
3036                 strbuf_add(tmp, filename, dirlen - 1);
3037                 if (mkdir(tmp->buf, 0777) && errno != EEXIST)
3038                         return -1;
3039                 if (adjust_shared_perm(tmp->buf))
3040                         return -1;
3041
3042                 /* Try again */
3043                 strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
3044                 fd = git_mkstemp_mode(tmp->buf, 0444);
3045         }
3046         return fd;
3047 }
3048
3049 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
3050                               const void *buf, unsigned long len, time_t mtime)
3051 {
3052         int fd, ret;
3053         unsigned char compressed[4096];
3054         git_zstream stream;
3055         git_SHA_CTX c;
3056         unsigned char parano_sha1[20];
3057         static struct strbuf tmp_file = STRBUF_INIT;
3058         const char *filename = sha1_file_name(sha1);
3059
3060         fd = create_tmpfile(&tmp_file, filename);
3061         if (fd < 0) {
3062                 if (errno == EACCES)
3063                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
3064                 else
3065                         return error("unable to create temporary file: %s", strerror(errno));
3066         }
3067
3068         /* Set it up */
3069         git_deflate_init(&stream, zlib_compression_level);
3070         stream.next_out = compressed;
3071         stream.avail_out = sizeof(compressed);
3072         git_SHA1_Init(&c);
3073
3074         /* First header.. */
3075         stream.next_in = (unsigned char *)hdr;
3076         stream.avail_in = hdrlen;
3077         while (git_deflate(&stream, 0) == Z_OK)
3078                 ; /* nothing */
3079         git_SHA1_Update(&c, hdr, hdrlen);
3080
3081         /* Then the data itself.. */
3082         stream.next_in = (void *)buf;
3083         stream.avail_in = len;
3084         do {
3085                 unsigned char *in0 = stream.next_in;
3086                 ret = git_deflate(&stream, Z_FINISH);
3087                 git_SHA1_Update(&c, in0, stream.next_in - in0);
3088                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
3089                         die("unable to write sha1 file");
3090                 stream.next_out = compressed;
3091                 stream.avail_out = sizeof(compressed);
3092         } while (ret == Z_OK);
3093
3094         if (ret != Z_STREAM_END)
3095                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
3096         ret = git_deflate_end_gently(&stream);
3097         if (ret != Z_OK)
3098                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
3099         git_SHA1_Final(parano_sha1, &c);
3100         if (hashcmp(sha1, parano_sha1) != 0)
3101                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
3102
3103         close_sha1_file(fd);
3104
3105         if (mtime) {
3106                 struct utimbuf utb;
3107                 utb.actime = mtime;
3108                 utb.modtime = mtime;
3109                 if (utime(tmp_file.buf, &utb) < 0)
3110                         warning("failed utime() on %s: %s",
3111                                 tmp_file.buf, strerror(errno));
3112         }
3113
3114         return finalize_object_file(tmp_file.buf, filename);
3115 }
3116
3117 static int freshen_loose_object(const unsigned char *sha1)
3118 {
3119         return check_and_freshen(sha1, 1);
3120 }
3121
3122 static int freshen_packed_object(const unsigned char *sha1)
3123 {
3124         struct pack_entry e;
3125         if (!find_pack_entry(sha1, &e))
3126                 return 0;
3127         if (e.p->freshened)
3128                 return 1;
3129         if (!freshen_file(e.p->pack_name))
3130                 return 0;
3131         e.p->freshened = 1;
3132         return 1;
3133 }
3134
3135 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
3136 {
3137         char hdr[32];
3138         int hdrlen = sizeof(hdr);
3139
3140         /* Normally if we have it in the pack then we do not bother writing
3141          * it out into .git/objects/??/?{38} file.
3142          */
3143         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
3144         if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3145                 return 0;
3146         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
3147 }
3148
3149 int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type,
3150                              unsigned char *sha1, unsigned flags)
3151 {
3152         char *header;
3153         int hdrlen, status = 0;
3154
3155         /* type string, SP, %lu of the length plus NUL must fit this */
3156         hdrlen = strlen(type) + 32;
3157         header = xmalloc(hdrlen);
3158         write_sha1_file_prepare(buf, len, type, sha1, header, &hdrlen);
3159
3160         if (!(flags & HASH_WRITE_OBJECT))
3161                 goto cleanup;
3162         if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3163                 goto cleanup;
3164         status = write_loose_object(sha1, header, hdrlen, buf, len, 0);
3165
3166 cleanup:
3167         free(header);
3168         return status;
3169 }
3170
3171 int force_object_loose(const unsigned char *sha1, time_t mtime)
3172 {
3173         void *buf;
3174         unsigned long len;
3175         enum object_type type;
3176         char hdr[32];
3177         int hdrlen;
3178         int ret;
3179
3180         if (has_loose_object(sha1))
3181                 return 0;
3182         buf = read_packed_sha1(sha1, &type, &len);
3183         if (!buf)
3184                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
3185         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(type), len) + 1;
3186         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
3187         free(buf);
3188
3189         return ret;
3190 }
3191
3192 int has_pack_index(const unsigned char *sha1)
3193 {
3194         struct stat st;
3195         if (stat(sha1_pack_index_name(sha1), &st))
3196                 return 0;
3197         return 1;
3198 }
3199
3200 int has_sha1_pack(const unsigned char *sha1)
3201 {
3202         struct pack_entry e;
3203         return find_pack_entry(sha1, &e);
3204 }
3205
3206 int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
3207 {
3208         struct pack_entry e;
3209
3210         if (find_pack_entry(sha1, &e))
3211                 return 1;
3212         if (has_loose_object(sha1))
3213                 return 1;
3214         if (flags & HAS_SHA1_QUICK)
3215                 return 0;
3216         reprepare_packed_git();
3217         return find_pack_entry(sha1, &e);
3218 }
3219
3220 int has_object_file(const struct object_id *oid)
3221 {
3222         return has_sha1_file(oid->hash);
3223 }
3224
3225 static void check_tree(const void *buf, size_t size)
3226 {
3227         struct tree_desc desc;
3228         struct name_entry entry;
3229
3230         init_tree_desc(&desc, buf, size);
3231         while (tree_entry(&desc, &entry))
3232                 /* do nothing
3233                  * tree_entry() will die() on malformed entries */
3234                 ;
3235 }
3236
3237 static void check_commit(const void *buf, size_t size)
3238 {
3239         struct commit c;
3240         memset(&c, 0, sizeof(c));
3241         if (parse_commit_buffer(&c, buf, size))
3242                 die("corrupt commit");
3243 }
3244
3245 static void check_tag(const void *buf, size_t size)
3246 {
3247         struct tag t;
3248         memset(&t, 0, sizeof(t));
3249         if (parse_tag_buffer(&t, buf, size))
3250                 die("corrupt tag");
3251 }
3252
3253 static int index_mem(unsigned char *sha1, void *buf, size_t size,
3254                      enum object_type type,
3255                      const char *path, unsigned flags)
3256 {
3257         int ret, re_allocated = 0;
3258         int write_object = flags & HASH_WRITE_OBJECT;
3259
3260         if (!type)
3261                 type = OBJ_BLOB;
3262
3263         /*
3264          * Convert blobs to git internal format
3265          */
3266         if ((type == OBJ_BLOB) && path) {
3267                 struct strbuf nbuf = STRBUF_INIT;
3268                 if (convert_to_git(path, buf, size, &nbuf,
3269                                    write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
3270                         buf = strbuf_detach(&nbuf, &size);
3271                         re_allocated = 1;
3272                 }
3273         }
3274         if (flags & HASH_FORMAT_CHECK) {
3275                 if (type == OBJ_TREE)
3276                         check_tree(buf, size);
3277                 if (type == OBJ_COMMIT)
3278                         check_commit(buf, size);
3279                 if (type == OBJ_TAG)
3280                         check_tag(buf, size);
3281         }
3282
3283         if (write_object)
3284                 ret = write_sha1_file(buf, size, typename(type), sha1);
3285         else
3286                 ret = hash_sha1_file(buf, size, typename(type), sha1);
3287         if (re_allocated)
3288                 free(buf);
3289         return ret;
3290 }
3291
3292 static int index_stream_convert_blob(unsigned char *sha1, int fd,
3293                                      const char *path, unsigned flags)
3294 {
3295         int ret;
3296         const int write_object = flags & HASH_WRITE_OBJECT;
3297         struct strbuf sbuf = STRBUF_INIT;
3298
3299         assert(path);
3300         assert(would_convert_to_git_filter_fd(path));
3301
3302         convert_to_git_filter_fd(path, fd, &sbuf,
3303                                  write_object ? safe_crlf : SAFE_CRLF_FALSE);
3304
3305         if (write_object)
3306                 ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3307                                       sha1);
3308         else
3309                 ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3310                                      sha1);
3311         strbuf_release(&sbuf);
3312         return ret;
3313 }
3314
3315 static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
3316                       const char *path, unsigned flags)
3317 {
3318         struct strbuf sbuf = STRBUF_INIT;
3319         int ret;
3320
3321         if (strbuf_read(&sbuf, fd, 4096) >= 0)
3322                 ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
3323         else
3324                 ret = -1;
3325         strbuf_release(&sbuf);
3326         return ret;
3327 }
3328
3329 #define SMALL_FILE_SIZE (32*1024)
3330
3331 static int index_core(unsigned char *sha1, int fd, size_t size,
3332                       enum object_type type, const char *path,
3333                       unsigned flags)
3334 {
3335         int ret;
3336
3337         if (!size) {
3338                 ret = index_mem(sha1, "", size, type, path, flags);
3339         } else if (size <= SMALL_FILE_SIZE) {
3340                 char *buf = xmalloc(size);
3341                 if (size == read_in_full(fd, buf, size))
3342                         ret = index_mem(sha1, buf, size, type, path, flags);
3343                 else
3344                         ret = error("short read %s", strerror(errno));
3345                 free(buf);
3346         } else {
3347                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
3348                 ret = index_mem(sha1, buf, size, type, path, flags);
3349                 munmap(buf, size);
3350         }
3351         return ret;
3352 }
3353
3354 /*
3355  * This creates one packfile per large blob unless bulk-checkin
3356  * machinery is "plugged".
3357  *
3358  * This also bypasses the usual "convert-to-git" dance, and that is on
3359  * purpose. We could write a streaming version of the converting
3360  * functions and insert that before feeding the data to fast-import
3361  * (or equivalent in-core API described above). However, that is
3362  * somewhat complicated, as we do not know the size of the filter
3363  * result, which we need to know beforehand when writing a git object.
3364  * Since the primary motivation for trying to stream from the working
3365  * tree file and to avoid mmaping it in core is to deal with large
3366  * binary blobs, they generally do not want to get any conversion, and
3367  * callers should avoid this code path when filters are requested.
3368  */
3369 static int index_stream(unsigned char *sha1, int fd, size_t size,
3370                         enum object_type type, const char *path,
3371                         unsigned flags)
3372 {
3373         return index_bulk_checkin(sha1, fd, size, type, path, flags);
3374 }
3375
3376 int index_fd(unsigned char *sha1, int fd, struct stat *st,
3377              enum object_type type, const char *path, unsigned flags)
3378 {
3379         int ret;
3380
3381         /*
3382          * Call xsize_t() only when needed to avoid potentially unnecessary
3383          * die() for large files.
3384          */
3385         if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
3386                 ret = index_stream_convert_blob(sha1, fd, path, flags);
3387         else if (!S_ISREG(st->st_mode))
3388                 ret = index_pipe(sha1, fd, type, path, flags);
3389         else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
3390                  (path && would_convert_to_git(path)))
3391                 ret = index_core(sha1, fd, xsize_t(st->st_size), type, path,
3392                                  flags);
3393         else
3394                 ret = index_stream(sha1, fd, xsize_t(st->st_size), type, path,
3395                                    flags);
3396         close(fd);
3397         return ret;
3398 }
3399
3400 int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3401 {
3402         int fd;
3403         struct strbuf sb = STRBUF_INIT;
3404
3405         switch (st->st_mode & S_IFMT) {
3406         case S_IFREG:
3407                 fd = open(path, O_RDONLY);
3408                 if (fd < 0)
3409                         return error("open(\"%s\"): %s", path,
3410                                      strerror(errno));
3411                 if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3412                         return error("%s: failed to insert into database",
3413                                      path);
3414                 break;
3415         case S_IFLNK:
3416                 if (strbuf_readlink(&sb, path, st->st_size)) {
3417                         char *errstr = strerror(errno);
3418                         return error("readlink(\"%s\"): %s", path,
3419                                      errstr);
3420                 }
3421                 if (!(flags & HASH_WRITE_OBJECT))
3422                         hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3423                 else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3424                         return error("%s: failed to insert into database",
3425                                      path);
3426                 strbuf_release(&sb);
3427                 break;
3428         case S_IFDIR:
3429                 return resolve_gitlink_ref(path, "HEAD", sha1);
3430         default:
3431                 return error("%s: unsupported file type", path);
3432         }
3433         return 0;
3434 }
3435
3436 int read_pack_header(int fd, struct pack_header *header)
3437 {
3438         if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3439                 /* "eof before pack header was fully read" */
3440                 return PH_ERROR_EOF;
3441
3442         if (header->hdr_signature != htonl(PACK_SIGNATURE))
3443                 /* "protocol error (pack signature mismatch detected)" */
3444                 return PH_ERROR_PACK_SIGNATURE;
3445         if (!pack_version_ok(header->hdr_version))
3446                 /* "protocol error (pack version unsupported)" */
3447                 return PH_ERROR_PROTOCOL;
3448         return 0;
3449 }
3450
3451 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3452 {
3453         enum object_type type = sha1_object_info(sha1, NULL);
3454         if (type < 0)
3455                 die("%s is not a valid object", sha1_to_hex(sha1));
3456         if (type != expect)
3457                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3458                     typename(expect));
3459 }
3460
3461 static int for_each_file_in_obj_subdir(int subdir_nr,
3462                                        struct strbuf *path,
3463                                        each_loose_object_fn obj_cb,
3464                                        each_loose_cruft_fn cruft_cb,
3465                                        each_loose_subdir_fn subdir_cb,
3466                                        void *data)
3467 {
3468         size_t baselen = path->len;
3469         DIR *dir = opendir(path->buf);
3470         struct dirent *de;
3471         int r = 0;
3472
3473         if (!dir) {
3474                 if (errno == ENOENT)
3475                         return 0;
3476                 return error("unable to open %s: %s", path->buf, strerror(errno));
3477         }
3478
3479         while ((de = readdir(dir))) {
3480                 if (is_dot_or_dotdot(de->d_name))
3481                         continue;
3482
3483                 strbuf_setlen(path, baselen);
3484                 strbuf_addf(path, "/%s", de->d_name);
3485
3486                 if (strlen(de->d_name) == 38)  {
3487                         char hex[41];
3488                         unsigned char sha1[20];
3489
3490                         snprintf(hex, sizeof(hex), "%02x%s",
3491                                  subdir_nr, de->d_name);
3492                         if (!get_sha1_hex(hex, sha1)) {
3493                                 if (obj_cb) {
3494                                         r = obj_cb(sha1, path->buf, data);
3495                                         if (r)
3496                                                 break;
3497                                 }
3498                                 continue;
3499                         }
3500                 }
3501
3502                 if (cruft_cb) {
3503                         r = cruft_cb(de->d_name, path->buf, data);
3504                         if (r)
3505                                 break;
3506                 }
3507         }
3508         closedir(dir);
3509
3510         strbuf_setlen(path, baselen);
3511         if (!r && subdir_cb)
3512                 r = subdir_cb(subdir_nr, path->buf, data);
3513
3514         return r;
3515 }
3516
3517 int for_each_loose_file_in_objdir_buf(struct strbuf *path,
3518                             each_loose_object_fn obj_cb,
3519                             each_loose_cruft_fn cruft_cb,
3520                             each_loose_subdir_fn subdir_cb,
3521                             void *data)
3522 {
3523         size_t baselen = path->len;
3524         int r = 0;
3525         int i;
3526
3527         for (i = 0; i < 256; i++) {
3528                 strbuf_addf(path, "/%02x", i);
3529                 r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
3530                                                 subdir_cb, data);
3531                 strbuf_setlen(path, baselen);
3532                 if (r)
3533                         break;
3534         }
3535
3536         return r;
3537 }
3538
3539 int for_each_loose_file_in_objdir(const char *path,
3540                                   each_loose_object_fn obj_cb,
3541                                   each_loose_cruft_fn cruft_cb,
3542                                   each_loose_subdir_fn subdir_cb,
3543                                   void *data)
3544 {
3545         struct strbuf buf = STRBUF_INIT;
3546         int r;
3547
3548         strbuf_addstr(&buf, path);
3549         r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
3550                                               subdir_cb, data);
3551         strbuf_release(&buf);
3552
3553         return r;
3554 }
3555
3556 struct loose_alt_odb_data {
3557         each_loose_object_fn *cb;
3558         void *data;
3559 };
3560
3561 static int loose_from_alt_odb(struct alternate_object_database *alt,
3562                               void *vdata)
3563 {
3564         struct loose_alt_odb_data *data = vdata;
3565         struct strbuf buf = STRBUF_INIT;
3566         int r;
3567
3568         /* copy base not including trailing '/' */
3569         strbuf_add(&buf, alt->base, alt->name - alt->base - 1);
3570         r = for_each_loose_file_in_objdir_buf(&buf,
3571                                               data->cb, NULL, NULL,
3572                                               data->data);
3573         strbuf_release(&buf);
3574         return r;
3575 }
3576
3577 int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
3578 {
3579         struct loose_alt_odb_data alt;
3580         int r;
3581
3582         r = for_each_loose_file_in_objdir(get_object_directory(),
3583                                           cb, NULL, NULL, data);
3584         if (r)
3585                 return r;
3586
3587         if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
3588                 return 0;
3589
3590         alt.cb = cb;
3591         alt.data = data;
3592         return foreach_alt_odb(loose_from_alt_odb, &alt);
3593 }
3594
3595 static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
3596 {
3597         uint32_t i;
3598         int r = 0;
3599
3600         for (i = 0; i < p->num_objects; i++) {
3601                 const unsigned char *sha1 = nth_packed_object_sha1(p, i);
3602
3603                 if (!sha1)
3604                         return error("unable to get sha1 of object %u in %s",
3605                                      i, p->pack_name);
3606
3607                 r = cb(sha1, p, i, data);
3608                 if (r)
3609                         break;
3610         }
3611         return r;
3612 }
3613
3614 int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
3615 {
3616         struct packed_git *p;
3617         int r = 0;
3618         int pack_errors = 0;
3619
3620         prepare_packed_git();
3621         for (p = packed_git; p; p = p->next) {
3622                 if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
3623                         continue;
3624                 if (open_pack_index(p)) {
3625                         pack_errors = 1;
3626                         continue;
3627                 }
3628                 r = for_each_object_in_pack(p, cb, data);
3629                 if (r)
3630                         break;
3631         }
3632         return r ? r : pack_errors;
3633 }