bash prompt: use bash builtins to check stash state
[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 "delta.h"
12 #include "pack.h"
13 #include "blob.h"
14 #include "commit.h"
15 #include "run-command.h"
16 #include "tag.h"
17 #include "tree.h"
18 #include "tree-walk.h"
19 #include "refs.h"
20 #include "pack-revindex.h"
21 #include "sha1-lookup.h"
22 #include "bulk-checkin.h"
23 #include "streaming.h"
24 #include "dir.h"
25
26 #ifndef O_NOATIME
27 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
28 #define O_NOATIME 01000000
29 #else
30 #define O_NOATIME 0
31 #endif
32 #endif
33
34 #define SZ_FMT PRIuMAX
35 static inline uintmax_t sz_fmt(size_t s) { return s; }
36
37 const unsigned char null_sha1[20];
38
39 static const char *no_log_pack_access = "no_log_pack_access";
40 static const char *log_pack_access;
41
42 /*
43  * This is meant to hold a *small* number of objects that you would
44  * want read_sha1_file() to be able to return, but yet you do not want
45  * to write them into the object store (e.g. a browse-only
46  * application).
47  */
48 static struct cached_object {
49         unsigned char sha1[20];
50         enum object_type type;
51         void *buf;
52         unsigned long size;
53 } *cached_objects;
54 static int cached_object_nr, cached_object_alloc;
55
56 static struct cached_object empty_tree = {
57         EMPTY_TREE_SHA1_BIN_LITERAL,
58         OBJ_TREE,
59         "",
60         0
61 };
62
63 static struct packed_git *last_found_pack;
64
65 static struct cached_object *find_cached_object(const unsigned char *sha1)
66 {
67         int i;
68         struct cached_object *co = cached_objects;
69
70         for (i = 0; i < cached_object_nr; i++, co++) {
71                 if (!hashcmp(co->sha1, sha1))
72                         return co;
73         }
74         if (!hashcmp(sha1, empty_tree.sha1))
75                 return &empty_tree;
76         return NULL;
77 }
78
79 int mkdir_in_gitdir(const char *path)
80 {
81         if (mkdir(path, 0777)) {
82                 int saved_errno = errno;
83                 struct stat st;
84                 struct strbuf sb = STRBUF_INIT;
85
86                 if (errno != EEXIST)
87                         return -1;
88                 /*
89                  * Are we looking at a path in a symlinked worktree
90                  * whose original repository does not yet have it?
91                  * e.g. .git/rr-cache pointing at its original
92                  * repository in which the user hasn't performed any
93                  * conflict resolution yet?
94                  */
95                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
96                     strbuf_readlink(&sb, path, st.st_size) ||
97                     !is_absolute_path(sb.buf) ||
98                     mkdir(sb.buf, 0777)) {
99                         strbuf_release(&sb);
100                         errno = saved_errno;
101                         return -1;
102                 }
103                 strbuf_release(&sb);
104         }
105         return adjust_shared_perm(path);
106 }
107
108 int safe_create_leading_directories(char *path)
109 {
110         char *pos = path + offset_1st_component(path);
111         struct stat st;
112
113         while (pos) {
114                 pos = strchr(pos, '/');
115                 if (!pos)
116                         break;
117                 while (*++pos == '/')
118                         ;
119                 if (!*pos)
120                         break;
121                 *--pos = '\0';
122                 if (!stat(path, &st)) {
123                         /* path exists */
124                         if (!S_ISDIR(st.st_mode)) {
125                                 *pos = '/';
126                                 return -3;
127                         }
128                 }
129                 else if (mkdir(path, 0777)) {
130                         if (errno == EEXIST &&
131                             !stat(path, &st) && S_ISDIR(st.st_mode)) {
132                                 ; /* somebody created it since we checked */
133                         } else {
134                                 *pos = '/';
135                                 return -1;
136                         }
137                 }
138                 else if (adjust_shared_perm(path)) {
139                         *pos = '/';
140                         return -2;
141                 }
142                 *pos++ = '/';
143         }
144         return 0;
145 }
146
147 int safe_create_leading_directories_const(const char *path)
148 {
149         /* path points to cache entries, so xstrdup before messing with it */
150         char *buf = xstrdup(path);
151         int result = safe_create_leading_directories(buf);
152         free(buf);
153         return result;
154 }
155
156 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
157 {
158         int i;
159         for (i = 0; i < 20; i++) {
160                 static char hex[] = "0123456789abcdef";
161                 unsigned int val = sha1[i];
162                 char *pos = pathbuf + i*2 + (i > 0);
163                 *pos++ = hex[val >> 4];
164                 *pos = hex[val & 0xf];
165         }
166 }
167
168 /*
169  * NOTE! This returns a statically allocated buffer, so you have to be
170  * careful about using it. Do an "xstrdup()" if you need to save the
171  * filename.
172  *
173  * Also note that this returns the location for creating.  Reading
174  * SHA1 file can happen from any alternate directory listed in the
175  * DB_ENVIRONMENT environment variable if it is not found in
176  * the primary object database.
177  */
178 char *sha1_file_name(const unsigned char *sha1)
179 {
180         static char buf[PATH_MAX];
181         const char *objdir;
182         int len;
183
184         objdir = get_object_directory();
185         len = strlen(objdir);
186
187         /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
188         if (len + 43 > PATH_MAX)
189                 die("insanely long object directory %s", objdir);
190         memcpy(buf, objdir, len);
191         buf[len] = '/';
192         buf[len+3] = '/';
193         buf[len+42] = '\0';
194         fill_sha1_path(buf + len + 1, sha1);
195         return buf;
196 }
197
198 static char *sha1_get_pack_name(const unsigned char *sha1,
199                                 char **name, char **base, const char *which)
200 {
201         static const char hex[] = "0123456789abcdef";
202         char *buf;
203         int i;
204
205         if (!*base) {
206                 const char *sha1_file_directory = get_object_directory();
207                 int len = strlen(sha1_file_directory);
208                 *base = xmalloc(len + 60);
209                 sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
210                         sha1_file_directory, which);
211                 *name = *base + len + 11;
212         }
213
214         buf = *name;
215
216         for (i = 0; i < 20; i++) {
217                 unsigned int val = *sha1++;
218                 *buf++ = hex[val >> 4];
219                 *buf++ = hex[val & 0xf];
220         }
221
222         return *base;
223 }
224
225 char *sha1_pack_name(const unsigned char *sha1)
226 {
227         static char *name, *base;
228
229         return sha1_get_pack_name(sha1, &name, &base, "pack");
230 }
231
232 char *sha1_pack_index_name(const unsigned char *sha1)
233 {
234         static char *name, *base;
235
236         return sha1_get_pack_name(sha1, &name, &base, "idx");
237 }
238
239 struct alternate_object_database *alt_odb_list;
240 static struct alternate_object_database **alt_odb_tail;
241
242 static int git_open_noatime(const char *name);
243
244 /*
245  * Prepare alternate object database registry.
246  *
247  * The variable alt_odb_list points at the list of struct
248  * alternate_object_database.  The elements on this list come from
249  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
250  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
251  * whose contents is similar to that environment variable but can be
252  * LF separated.  Its base points at a statically allocated buffer that
253  * contains "/the/directory/corresponding/to/.git/objects/...", while
254  * its name points just after the slash at the end of ".git/objects/"
255  * in the example above, and has enough space to hold 40-byte hex
256  * SHA1, an extra slash for the first level indirection, and the
257  * terminating NUL.
258  */
259 static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth)
260 {
261         const char *objdir = get_object_directory();
262         struct alternate_object_database *ent;
263         struct alternate_object_database *alt;
264         int pfxlen, entlen;
265         struct strbuf pathbuf = STRBUF_INIT;
266
267         if (!is_absolute_path(entry) && relative_base) {
268                 strbuf_addstr(&pathbuf, real_path(relative_base));
269                 strbuf_addch(&pathbuf, '/');
270         }
271         strbuf_addstr(&pathbuf, entry);
272
273         normalize_path_copy(pathbuf.buf, pathbuf.buf);
274
275         pfxlen = strlen(pathbuf.buf);
276
277         /*
278          * The trailing slash after the directory name is given by
279          * this function at the end. Remove duplicates.
280          */
281         while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
282                 pfxlen -= 1;
283
284         entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
285         ent = xmalloc(sizeof(*ent) + entlen);
286         memcpy(ent->base, pathbuf.buf, pfxlen);
287         strbuf_release(&pathbuf);
288
289         ent->name = ent->base + pfxlen + 1;
290         ent->base[pfxlen + 3] = '/';
291         ent->base[pfxlen] = ent->base[entlen-1] = 0;
292
293         /* Detect cases where alternate disappeared */
294         if (!is_directory(ent->base)) {
295                 error("object directory %s does not exist; "
296                       "check .git/objects/info/alternates.",
297                       ent->base);
298                 free(ent);
299                 return -1;
300         }
301
302         /* Prevent the common mistake of listing the same
303          * thing twice, or object directory itself.
304          */
305         for (alt = alt_odb_list; alt; alt = alt->next) {
306                 if (!memcmp(ent->base, alt->base, pfxlen)) {
307                         free(ent);
308                         return -1;
309                 }
310         }
311         if (!strcmp(ent->base, objdir)) {
312                 free(ent);
313                 return -1;
314         }
315
316         /* add the alternate entry */
317         *alt_odb_tail = ent;
318         alt_odb_tail = &(ent->next);
319         ent->next = NULL;
320
321         /* recursively add alternates */
322         read_info_alternates(ent->base, depth + 1);
323
324         ent->base[pfxlen] = '/';
325
326         return 0;
327 }
328
329 static void link_alt_odb_entries(const char *alt, int len, int sep,
330                                  const char *relative_base, int depth)
331 {
332         struct string_list entries = STRING_LIST_INIT_NODUP;
333         char *alt_copy;
334         int i;
335
336         if (depth > 5) {
337                 error("%s: ignoring alternate object stores, nesting too deep.",
338                                 relative_base);
339                 return;
340         }
341
342         alt_copy = xmemdupz(alt, len);
343         string_list_split_in_place(&entries, alt_copy, sep, -1);
344         for (i = 0; i < entries.nr; i++) {
345                 const char *entry = entries.items[i].string;
346                 if (entry[0] == '\0' || entry[0] == '#')
347                         continue;
348                 if (!is_absolute_path(entry) && depth) {
349                         error("%s: ignoring relative alternate object store %s",
350                                         relative_base, entry);
351                 } else {
352                         link_alt_odb_entry(entry, relative_base, depth);
353                 }
354         }
355         string_list_clear(&entries, 0);
356         free(alt_copy);
357 }
358
359 void read_info_alternates(const char * relative_base, int depth)
360 {
361         char *map;
362         size_t mapsz;
363         struct stat st;
364         const char alt_file_name[] = "info/alternates";
365         /* Given that relative_base is no longer than PATH_MAX,
366            ensure that "path" has enough space to append "/", the
367            file name, "info/alternates", and a trailing NUL.  */
368         char path[PATH_MAX + 1 + sizeof alt_file_name];
369         int fd;
370
371         sprintf(path, "%s/%s", relative_base, alt_file_name);
372         fd = git_open_noatime(path);
373         if (fd < 0)
374                 return;
375         if (fstat(fd, &st) || (st.st_size == 0)) {
376                 close(fd);
377                 return;
378         }
379         mapsz = xsize_t(st.st_size);
380         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
381         close(fd);
382
383         link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
384
385         munmap(map, mapsz);
386 }
387
388 void add_to_alternates_file(const char *reference)
389 {
390         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
391         int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
392         char *alt = mkpath("%s\n", reference);
393         write_or_die(fd, alt, strlen(alt));
394         if (commit_lock_file(lock))
395                 die("could not close alternates file");
396         if (alt_odb_tail)
397                 link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
398 }
399
400 void foreach_alt_odb(alt_odb_fn fn, void *cb)
401 {
402         struct alternate_object_database *ent;
403
404         prepare_alt_odb();
405         for (ent = alt_odb_list; ent; ent = ent->next)
406                 if (fn(ent, cb))
407                         return;
408 }
409
410 void prepare_alt_odb(void)
411 {
412         const char *alt;
413
414         if (alt_odb_tail)
415                 return;
416
417         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
418         if (!alt) alt = "";
419
420         alt_odb_tail = &alt_odb_list;
421         link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
422
423         read_info_alternates(get_object_directory(), 0);
424 }
425
426 static int has_loose_object_local(const unsigned char *sha1)
427 {
428         char *name = sha1_file_name(sha1);
429         return !access(name, F_OK);
430 }
431
432 int has_loose_object_nonlocal(const unsigned char *sha1)
433 {
434         struct alternate_object_database *alt;
435         prepare_alt_odb();
436         for (alt = alt_odb_list; alt; alt = alt->next) {
437                 fill_sha1_path(alt->name, sha1);
438                 if (!access(alt->base, F_OK))
439                         return 1;
440         }
441         return 0;
442 }
443
444 static int has_loose_object(const unsigned char *sha1)
445 {
446         return has_loose_object_local(sha1) ||
447                has_loose_object_nonlocal(sha1);
448 }
449
450 static unsigned int pack_used_ctr;
451 static unsigned int pack_mmap_calls;
452 static unsigned int peak_pack_open_windows;
453 static unsigned int pack_open_windows;
454 static unsigned int pack_open_fds;
455 static unsigned int pack_max_fds;
456 static size_t peak_pack_mapped;
457 static size_t pack_mapped;
458 struct packed_git *packed_git;
459
460 void pack_report(void)
461 {
462         fprintf(stderr,
463                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
464                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
465                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
466                 sz_fmt(getpagesize()),
467                 sz_fmt(packed_git_window_size),
468                 sz_fmt(packed_git_limit));
469         fprintf(stderr,
470                 "pack_report: pack_used_ctr            = %10u\n"
471                 "pack_report: pack_mmap_calls          = %10u\n"
472                 "pack_report: pack_open_windows        = %10u / %10u\n"
473                 "pack_report: pack_mapped              = "
474                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
475                 pack_used_ctr,
476                 pack_mmap_calls,
477                 pack_open_windows, peak_pack_open_windows,
478                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
479 }
480
481 static int check_packed_git_idx(const char *path,  struct packed_git *p)
482 {
483         void *idx_map;
484         struct pack_idx_header *hdr;
485         size_t idx_size;
486         uint32_t version, nr, i, *index;
487         int fd = git_open_noatime(path);
488         struct stat st;
489
490         if (fd < 0)
491                 return -1;
492         if (fstat(fd, &st)) {
493                 close(fd);
494                 return -1;
495         }
496         idx_size = xsize_t(st.st_size);
497         if (idx_size < 4 * 256 + 20 + 20) {
498                 close(fd);
499                 return error("index file %s is too small", path);
500         }
501         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
502         close(fd);
503
504         hdr = idx_map;
505         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
506                 version = ntohl(hdr->idx_version);
507                 if (version < 2 || version > 2) {
508                         munmap(idx_map, idx_size);
509                         return error("index file %s is version %"PRIu32
510                                      " and is not supported by this binary"
511                                      " (try upgrading GIT to a newer version)",
512                                      path, version);
513                 }
514         } else
515                 version = 1;
516
517         nr = 0;
518         index = idx_map;
519         if (version > 1)
520                 index += 2;  /* skip index header */
521         for (i = 0; i < 256; i++) {
522                 uint32_t n = ntohl(index[i]);
523                 if (n < nr) {
524                         munmap(idx_map, idx_size);
525                         return error("non-monotonic index %s", path);
526                 }
527                 nr = n;
528         }
529
530         if (version == 1) {
531                 /*
532                  * Total size:
533                  *  - 256 index entries 4 bytes each
534                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
535                  *  - 20-byte SHA1 of the packfile
536                  *  - 20-byte SHA1 file checksum
537                  */
538                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
539                         munmap(idx_map, idx_size);
540                         return error("wrong index v1 file size in %s", path);
541                 }
542         } else if (version == 2) {
543                 /*
544                  * Minimum size:
545                  *  - 8 bytes of header
546                  *  - 256 index entries 4 bytes each
547                  *  - 20-byte sha1 entry * nr
548                  *  - 4-byte crc entry * nr
549                  *  - 4-byte offset entry * nr
550                  *  - 20-byte SHA1 of the packfile
551                  *  - 20-byte SHA1 file checksum
552                  * And after the 4-byte offset table might be a
553                  * variable sized table containing 8-byte entries
554                  * for offsets larger than 2^31.
555                  */
556                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
557                 unsigned long max_size = min_size;
558                 if (nr)
559                         max_size += (nr - 1)*8;
560                 if (idx_size < min_size || idx_size > max_size) {
561                         munmap(idx_map, idx_size);
562                         return error("wrong index v2 file size in %s", path);
563                 }
564                 if (idx_size != min_size &&
565                     /*
566                      * make sure we can deal with large pack offsets.
567                      * 31-bit signed offset won't be enough, neither
568                      * 32-bit unsigned one will be.
569                      */
570                     (sizeof(off_t) <= 4)) {
571                         munmap(idx_map, idx_size);
572                         return error("pack too large for current definition of off_t in %s", path);
573                 }
574         }
575
576         p->index_version = version;
577         p->index_data = idx_map;
578         p->index_size = idx_size;
579         p->num_objects = nr;
580         return 0;
581 }
582
583 int open_pack_index(struct packed_git *p)
584 {
585         char *idx_name;
586         int ret;
587
588         if (p->index_data)
589                 return 0;
590
591         idx_name = xstrdup(p->pack_name);
592         strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
593         ret = check_packed_git_idx(idx_name, p);
594         free(idx_name);
595         return ret;
596 }
597
598 static void scan_windows(struct packed_git *p,
599         struct packed_git **lru_p,
600         struct pack_window **lru_w,
601         struct pack_window **lru_l)
602 {
603         struct pack_window *w, *w_l;
604
605         for (w_l = NULL, w = p->windows; w; w = w->next) {
606                 if (!w->inuse_cnt) {
607                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
608                                 *lru_p = p;
609                                 *lru_w = w;
610                                 *lru_l = w_l;
611                         }
612                 }
613                 w_l = w;
614         }
615 }
616
617 static int unuse_one_window(struct packed_git *current, int keep_fd)
618 {
619         struct packed_git *p, *lru_p = NULL;
620         struct pack_window *lru_w = NULL, *lru_l = NULL;
621
622         if (current)
623                 scan_windows(current, &lru_p, &lru_w, &lru_l);
624         for (p = packed_git; p; p = p->next)
625                 scan_windows(p, &lru_p, &lru_w, &lru_l);
626         if (lru_p) {
627                 munmap(lru_w->base, lru_w->len);
628                 pack_mapped -= lru_w->len;
629                 if (lru_l)
630                         lru_l->next = lru_w->next;
631                 else {
632                         lru_p->windows = lru_w->next;
633                         if (!lru_p->windows && lru_p->pack_fd != -1
634                                 && lru_p->pack_fd != keep_fd) {
635                                 close(lru_p->pack_fd);
636                                 pack_open_fds--;
637                                 lru_p->pack_fd = -1;
638                         }
639                 }
640                 free(lru_w);
641                 pack_open_windows--;
642                 return 1;
643         }
644         return 0;
645 }
646
647 void release_pack_memory(size_t need, int fd)
648 {
649         size_t cur = pack_mapped;
650         while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
651                 ; /* nothing */
652 }
653
654 void *xmmap(void *start, size_t length,
655         int prot, int flags, int fd, off_t offset)
656 {
657         void *ret = mmap(start, length, prot, flags, fd, offset);
658         if (ret == MAP_FAILED) {
659                 if (!length)
660                         return NULL;
661                 release_pack_memory(length, fd);
662                 ret = mmap(start, length, prot, flags, fd, offset);
663                 if (ret == MAP_FAILED)
664                         die_errno("Out of memory? mmap failed");
665         }
666         return ret;
667 }
668
669 void close_pack_windows(struct packed_git *p)
670 {
671         while (p->windows) {
672                 struct pack_window *w = p->windows;
673
674                 if (w->inuse_cnt)
675                         die("pack '%s' still has open windows to it",
676                             p->pack_name);
677                 munmap(w->base, w->len);
678                 pack_mapped -= w->len;
679                 pack_open_windows--;
680                 p->windows = w->next;
681                 free(w);
682         }
683 }
684
685 void unuse_pack(struct pack_window **w_cursor)
686 {
687         struct pack_window *w = *w_cursor;
688         if (w) {
689                 w->inuse_cnt--;
690                 *w_cursor = NULL;
691         }
692 }
693
694 void close_pack_index(struct packed_git *p)
695 {
696         if (p->index_data) {
697                 munmap((void *)p->index_data, p->index_size);
698                 p->index_data = NULL;
699         }
700 }
701
702 /*
703  * This is used by git-repack in case a newly created pack happens to
704  * contain the same set of objects as an existing one.  In that case
705  * the resulting file might be different even if its name would be the
706  * same.  It is best to close any reference to the old pack before it is
707  * replaced on disk.  Of course no index pointers nor windows for given pack
708  * must subsist at this point.  If ever objects from this pack are requested
709  * again, the new version of the pack will be reinitialized through
710  * reprepare_packed_git().
711  */
712 void free_pack_by_name(const char *pack_name)
713 {
714         struct packed_git *p, **pp = &packed_git;
715
716         while (*pp) {
717                 p = *pp;
718                 if (strcmp(pack_name, p->pack_name) == 0) {
719                         clear_delta_base_cache();
720                         close_pack_windows(p);
721                         if (p->pack_fd != -1) {
722                                 close(p->pack_fd);
723                                 pack_open_fds--;
724                         }
725                         close_pack_index(p);
726                         free(p->bad_object_sha1);
727                         *pp = p->next;
728                         if (last_found_pack == p)
729                                 last_found_pack = NULL;
730                         free(p);
731                         return;
732                 }
733                 pp = &p->next;
734         }
735 }
736
737 static unsigned int get_max_fd_limit(void)
738 {
739 #ifdef RLIMIT_NOFILE
740         struct rlimit lim;
741
742         if (getrlimit(RLIMIT_NOFILE, &lim))
743                 die_errno("cannot get RLIMIT_NOFILE");
744
745         return lim.rlim_cur;
746 #elif defined(_SC_OPEN_MAX)
747         return sysconf(_SC_OPEN_MAX);
748 #elif defined(OPEN_MAX)
749         return OPEN_MAX;
750 #else
751         return 1; /* see the caller ;-) */
752 #endif
753 }
754
755 /*
756  * Do not call this directly as this leaks p->pack_fd on error return;
757  * call open_packed_git() instead.
758  */
759 static int open_packed_git_1(struct packed_git *p)
760 {
761         struct stat st;
762         struct pack_header hdr;
763         unsigned char sha1[20];
764         unsigned char *idx_sha1;
765         long fd_flag;
766
767         if (!p->index_data && open_pack_index(p))
768                 return error("packfile %s index unavailable", p->pack_name);
769
770         if (!pack_max_fds) {
771                 unsigned int max_fds = get_max_fd_limit();
772
773                 /* Save 3 for stdin/stdout/stderr, 22 for work */
774                 if (25 < max_fds)
775                         pack_max_fds = max_fds - 25;
776                 else
777                         pack_max_fds = 1;
778         }
779
780         while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
781                 ; /* nothing */
782
783         p->pack_fd = git_open_noatime(p->pack_name);
784         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
785                 return -1;
786         pack_open_fds++;
787
788         /* If we created the struct before we had the pack we lack size. */
789         if (!p->pack_size) {
790                 if (!S_ISREG(st.st_mode))
791                         return error("packfile %s not a regular file", p->pack_name);
792                 p->pack_size = st.st_size;
793         } else if (p->pack_size != st.st_size)
794                 return error("packfile %s size changed", p->pack_name);
795
796         /* We leave these file descriptors open with sliding mmap;
797          * there is no point keeping them open across exec(), though.
798          */
799         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
800         if (fd_flag < 0)
801                 return error("cannot determine file descriptor flags");
802         fd_flag |= FD_CLOEXEC;
803         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
804                 return error("cannot set FD_CLOEXEC");
805
806         /* Verify we recognize this pack file format. */
807         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
808                 return error("file %s is far too short to be a packfile", p->pack_name);
809         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
810                 return error("file %s is not a GIT packfile", p->pack_name);
811         if (!pack_version_ok(hdr.hdr_version))
812                 return error("packfile %s is version %"PRIu32" and not"
813                         " supported (try upgrading GIT to a newer version)",
814                         p->pack_name, ntohl(hdr.hdr_version));
815
816         /* Verify the pack matches its index. */
817         if (p->num_objects != ntohl(hdr.hdr_entries))
818                 return error("packfile %s claims to have %"PRIu32" objects"
819                              " while index indicates %"PRIu32" objects",
820                              p->pack_name, ntohl(hdr.hdr_entries),
821                              p->num_objects);
822         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
823                 return error("end of packfile %s is unavailable", p->pack_name);
824         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
825                 return error("packfile %s signature is unavailable", p->pack_name);
826         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
827         if (hashcmp(sha1, idx_sha1))
828                 return error("packfile %s does not match index", p->pack_name);
829         return 0;
830 }
831
832 static int open_packed_git(struct packed_git *p)
833 {
834         if (!open_packed_git_1(p))
835                 return 0;
836         if (p->pack_fd != -1) {
837                 close(p->pack_fd);
838                 pack_open_fds--;
839                 p->pack_fd = -1;
840         }
841         return -1;
842 }
843
844 static int in_window(struct pack_window *win, off_t offset)
845 {
846         /* We must promise at least 20 bytes (one hash) after the
847          * offset is available from this window, otherwise the offset
848          * is not actually in this window and a different window (which
849          * has that one hash excess) must be used.  This is to support
850          * the object header and delta base parsing routines below.
851          */
852         off_t win_off = win->offset;
853         return win_off <= offset
854                 && (offset + 20) <= (win_off + win->len);
855 }
856
857 unsigned char *use_pack(struct packed_git *p,
858                 struct pack_window **w_cursor,
859                 off_t offset,
860                 unsigned long *left)
861 {
862         struct pack_window *win = *w_cursor;
863
864         /* Since packfiles end in a hash of their content and it's
865          * pointless to ask for an offset into the middle of that
866          * hash, and the in_window function above wouldn't match
867          * don't allow an offset too close to the end of the file.
868          */
869         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
870                 die("packfile %s cannot be accessed", p->pack_name);
871         if (offset > (p->pack_size - 20))
872                 die("offset beyond end of packfile (truncated pack?)");
873
874         if (!win || !in_window(win, offset)) {
875                 if (win)
876                         win->inuse_cnt--;
877                 for (win = p->windows; win; win = win->next) {
878                         if (in_window(win, offset))
879                                 break;
880                 }
881                 if (!win) {
882                         size_t window_align = packed_git_window_size / 2;
883                         off_t len;
884
885                         if (p->pack_fd == -1 && open_packed_git(p))
886                                 die("packfile %s cannot be accessed", p->pack_name);
887
888                         win = xcalloc(1, sizeof(*win));
889                         win->offset = (offset / window_align) * window_align;
890                         len = p->pack_size - win->offset;
891                         if (len > packed_git_window_size)
892                                 len = packed_git_window_size;
893                         win->len = (size_t)len;
894                         pack_mapped += win->len;
895                         while (packed_git_limit < pack_mapped
896                                 && unuse_one_window(p, p->pack_fd))
897                                 ; /* nothing */
898                         win->base = xmmap(NULL, win->len,
899                                 PROT_READ, MAP_PRIVATE,
900                                 p->pack_fd, win->offset);
901                         if (win->base == MAP_FAILED)
902                                 die("packfile %s cannot be mapped: %s",
903                                         p->pack_name,
904                                         strerror(errno));
905                         if (!win->offset && win->len == p->pack_size
906                                 && !p->do_not_close) {
907                                 close(p->pack_fd);
908                                 pack_open_fds--;
909                                 p->pack_fd = -1;
910                         }
911                         pack_mmap_calls++;
912                         pack_open_windows++;
913                         if (pack_mapped > peak_pack_mapped)
914                                 peak_pack_mapped = pack_mapped;
915                         if (pack_open_windows > peak_pack_open_windows)
916                                 peak_pack_open_windows = pack_open_windows;
917                         win->next = p->windows;
918                         p->windows = win;
919                 }
920         }
921         if (win != *w_cursor) {
922                 win->last_used = pack_used_ctr++;
923                 win->inuse_cnt++;
924                 *w_cursor = win;
925         }
926         offset -= win->offset;
927         if (left)
928                 *left = win->len - xsize_t(offset);
929         return win->base + offset;
930 }
931
932 static struct packed_git *alloc_packed_git(int extra)
933 {
934         struct packed_git *p = xmalloc(sizeof(*p) + extra);
935         memset(p, 0, sizeof(*p));
936         p->pack_fd = -1;
937         return p;
938 }
939
940 static void try_to_free_pack_memory(size_t size)
941 {
942         release_pack_memory(size, -1);
943 }
944
945 struct packed_git *add_packed_git(const char *path, int path_len, int local)
946 {
947         static int have_set_try_to_free_routine;
948         struct stat st;
949         struct packed_git *p = alloc_packed_git(path_len + 2);
950
951         if (!have_set_try_to_free_routine) {
952                 have_set_try_to_free_routine = 1;
953                 set_try_to_free_routine(try_to_free_pack_memory);
954         }
955
956         /*
957          * Make sure a corresponding .pack file exists and that
958          * the index looks sane.
959          */
960         path_len -= strlen(".idx");
961         if (path_len < 1) {
962                 free(p);
963                 return NULL;
964         }
965         memcpy(p->pack_name, path, path_len);
966
967         strcpy(p->pack_name + path_len, ".keep");
968         if (!access(p->pack_name, F_OK))
969                 p->pack_keep = 1;
970
971         strcpy(p->pack_name + path_len, ".pack");
972         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
973                 free(p);
974                 return NULL;
975         }
976
977         /* ok, it looks sane as far as we can check without
978          * actually mapping the pack file.
979          */
980         p->pack_size = st.st_size;
981         p->pack_local = local;
982         p->mtime = st.st_mtime;
983         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
984                 hashclr(p->sha1);
985         return p;
986 }
987
988 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
989 {
990         const char *path = sha1_pack_name(sha1);
991         struct packed_git *p = alloc_packed_git(strlen(path) + 1);
992
993         strcpy(p->pack_name, path);
994         hashcpy(p->sha1, sha1);
995         if (check_packed_git_idx(idx_path, p)) {
996                 free(p);
997                 return NULL;
998         }
999
1000         return p;
1001 }
1002
1003 void install_packed_git(struct packed_git *pack)
1004 {
1005         if (pack->pack_fd != -1)
1006                 pack_open_fds++;
1007
1008         pack->next = packed_git;
1009         packed_git = pack;
1010 }
1011
1012 void (*report_garbage)(const char *desc, const char *path);
1013
1014 static void report_helper(const struct string_list *list,
1015                           int seen_bits, int first, int last)
1016 {
1017         const char *msg;
1018         switch (seen_bits) {
1019         case 0:
1020                 msg = "no corresponding .idx nor .pack";
1021                 break;
1022         case 1:
1023                 msg = "no corresponding .idx";
1024                 break;
1025         case 2:
1026                 msg = "no corresponding .pack";
1027                 break;
1028         default:
1029                 return;
1030         }
1031         for (; first < last; first++)
1032                 report_garbage(msg, list->items[first].string);
1033 }
1034
1035 static void report_pack_garbage(struct string_list *list)
1036 {
1037         int i, baselen = -1, first = 0, seen_bits = 0;
1038
1039         if (!report_garbage)
1040                 return;
1041
1042         sort_string_list(list);
1043
1044         for (i = 0; i < list->nr; i++) {
1045                 const char *path = list->items[i].string;
1046                 if (baselen != -1 &&
1047                     strncmp(path, list->items[first].string, baselen)) {
1048                         report_helper(list, seen_bits, first, i);
1049                         baselen = -1;
1050                         seen_bits = 0;
1051                 }
1052                 if (baselen == -1) {
1053                         const char *dot = strrchr(path, '.');
1054                         if (!dot) {
1055                                 report_garbage("garbage found", path);
1056                                 continue;
1057                         }
1058                         baselen = dot - path + 1;
1059                         first = i;
1060                 }
1061                 if (!strcmp(path + baselen, "pack"))
1062                         seen_bits |= 1;
1063                 else if (!strcmp(path + baselen, "idx"))
1064                         seen_bits |= 2;
1065         }
1066         report_helper(list, seen_bits, first, list->nr);
1067 }
1068
1069 static void prepare_packed_git_one(char *objdir, int local)
1070 {
1071         /* Ensure that this buffer is large enough so that we can
1072            append "/pack/" without clobbering the stack even if
1073            strlen(objdir) were PATH_MAX.  */
1074         char path[PATH_MAX + 1 + 4 + 1 + 1];
1075         int len;
1076         DIR *dir;
1077         struct dirent *de;
1078         struct string_list garbage = STRING_LIST_INIT_DUP;
1079
1080         sprintf(path, "%s/pack", objdir);
1081         len = strlen(path);
1082         dir = opendir(path);
1083         if (!dir) {
1084                 if (errno != ENOENT)
1085                         error("unable to open object pack directory: %s: %s",
1086                               path, strerror(errno));
1087                 return;
1088         }
1089         path[len++] = '/';
1090         while ((de = readdir(dir)) != NULL) {
1091                 int namelen = strlen(de->d_name);
1092                 struct packed_git *p;
1093
1094                 if (len + namelen + 1 > sizeof(path)) {
1095                         if (report_garbage) {
1096                                 struct strbuf sb = STRBUF_INIT;
1097                                 strbuf_addf(&sb, "%.*s/%s", len - 1, path, de->d_name);
1098                                 report_garbage("path too long", sb.buf);
1099                                 strbuf_release(&sb);
1100                         }
1101                         continue;
1102                 }
1103
1104                 if (is_dot_or_dotdot(de->d_name))
1105                         continue;
1106
1107                 strcpy(path + len, de->d_name);
1108
1109                 if (has_extension(de->d_name, ".idx")) {
1110                         /* Don't reopen a pack we already have. */
1111                         for (p = packed_git; p; p = p->next) {
1112                                 if (!memcmp(path, p->pack_name, len + namelen - 4))
1113                                         break;
1114                         }
1115                         if (p == NULL &&
1116                             /*
1117                              * See if it really is a valid .idx file with
1118                              * corresponding .pack file that we can map.
1119                              */
1120                             (p = add_packed_git(path, len + namelen, local)) != NULL)
1121                                 install_packed_git(p);
1122                 }
1123
1124                 if (!report_garbage)
1125                         continue;
1126
1127                 if (has_extension(de->d_name, ".idx") ||
1128                     has_extension(de->d_name, ".pack") ||
1129                     has_extension(de->d_name, ".keep"))
1130                         string_list_append(&garbage, path);
1131                 else
1132                         report_garbage("garbage found", path);
1133         }
1134         closedir(dir);
1135         report_pack_garbage(&garbage);
1136         string_list_clear(&garbage, 0);
1137 }
1138
1139 static int sort_pack(const void *a_, const void *b_)
1140 {
1141         struct packed_git *a = *((struct packed_git **)a_);
1142         struct packed_git *b = *((struct packed_git **)b_);
1143         int st;
1144
1145         /*
1146          * Local packs tend to contain objects specific to our
1147          * variant of the project than remote ones.  In addition,
1148          * remote ones could be on a network mounted filesystem.
1149          * Favor local ones for these reasons.
1150          */
1151         st = a->pack_local - b->pack_local;
1152         if (st)
1153                 return -st;
1154
1155         /*
1156          * Younger packs tend to contain more recent objects,
1157          * and more recent objects tend to get accessed more
1158          * often.
1159          */
1160         if (a->mtime < b->mtime)
1161                 return 1;
1162         else if (a->mtime == b->mtime)
1163                 return 0;
1164         return -1;
1165 }
1166
1167 static void rearrange_packed_git(void)
1168 {
1169         struct packed_git **ary, *p;
1170         int i, n;
1171
1172         for (n = 0, p = packed_git; p; p = p->next)
1173                 n++;
1174         if (n < 2)
1175                 return;
1176
1177         /* prepare an array of packed_git for easier sorting */
1178         ary = xcalloc(n, sizeof(struct packed_git *));
1179         for (n = 0, p = packed_git; p; p = p->next)
1180                 ary[n++] = p;
1181
1182         qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1183
1184         /* link them back again */
1185         for (i = 0; i < n - 1; i++)
1186                 ary[i]->next = ary[i + 1];
1187         ary[n - 1]->next = NULL;
1188         packed_git = ary[0];
1189
1190         free(ary);
1191 }
1192
1193 static int prepare_packed_git_run_once = 0;
1194 void prepare_packed_git(void)
1195 {
1196         struct alternate_object_database *alt;
1197
1198         if (prepare_packed_git_run_once)
1199                 return;
1200         prepare_packed_git_one(get_object_directory(), 1);
1201         prepare_alt_odb();
1202         for (alt = alt_odb_list; alt; alt = alt->next) {
1203                 alt->name[-1] = 0;
1204                 prepare_packed_git_one(alt->base, 0);
1205                 alt->name[-1] = '/';
1206         }
1207         rearrange_packed_git();
1208         prepare_packed_git_run_once = 1;
1209 }
1210
1211 void reprepare_packed_git(void)
1212 {
1213         discard_revindex();
1214         prepare_packed_git_run_once = 0;
1215         prepare_packed_git();
1216 }
1217
1218 static void mark_bad_packed_object(struct packed_git *p,
1219                                    const unsigned char *sha1)
1220 {
1221         unsigned i;
1222         for (i = 0; i < p->num_bad_objects; i++)
1223                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1224                         return;
1225         p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1226         hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1227         p->num_bad_objects++;
1228 }
1229
1230 static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1231 {
1232         struct packed_git *p;
1233         unsigned i;
1234
1235         for (p = packed_git; p; p = p->next)
1236                 for (i = 0; i < p->num_bad_objects; i++)
1237                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1238                                 return p;
1239         return NULL;
1240 }
1241
1242 /*
1243  * With an in-core object data in "map", rehash it to make sure the
1244  * object name actually matches "sha1" to detect object corruption.
1245  * With "map" == NULL, try reading the object named with "sha1" using
1246  * the streaming interface and rehash it to do the same.
1247  */
1248 int check_sha1_signature(const unsigned char *sha1, void *map,
1249                          unsigned long size, const char *type)
1250 {
1251         unsigned char real_sha1[20];
1252         enum object_type obj_type;
1253         struct git_istream *st;
1254         git_SHA_CTX c;
1255         char hdr[32];
1256         int hdrlen;
1257
1258         if (map) {
1259                 hash_sha1_file(map, size, type, real_sha1);
1260                 return hashcmp(sha1, real_sha1) ? -1 : 0;
1261         }
1262
1263         st = open_istream(sha1, &obj_type, &size, NULL);
1264         if (!st)
1265                 return -1;
1266
1267         /* Generate the header */
1268         hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
1269
1270         /* Sha1.. */
1271         git_SHA1_Init(&c);
1272         git_SHA1_Update(&c, hdr, hdrlen);
1273         for (;;) {
1274                 char buf[1024 * 16];
1275                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
1276
1277                 if (readlen < 0) {
1278                         close_istream(st);
1279                         return -1;
1280                 }
1281                 if (!readlen)
1282                         break;
1283                 git_SHA1_Update(&c, buf, readlen);
1284         }
1285         git_SHA1_Final(real_sha1, &c);
1286         close_istream(st);
1287         return hashcmp(sha1, real_sha1) ? -1 : 0;
1288 }
1289
1290 static int git_open_noatime(const char *name)
1291 {
1292         static int sha1_file_open_flag = O_NOATIME;
1293
1294         for (;;) {
1295                 int fd = open(name, O_RDONLY | sha1_file_open_flag);
1296                 if (fd >= 0)
1297                         return fd;
1298
1299                 /* Might the failure be due to O_NOATIME? */
1300                 if (errno != ENOENT && sha1_file_open_flag) {
1301                         sha1_file_open_flag = 0;
1302                         continue;
1303                 }
1304
1305                 return -1;
1306         }
1307 }
1308
1309 static int open_sha1_file(const unsigned char *sha1)
1310 {
1311         int fd;
1312         char *name = sha1_file_name(sha1);
1313         struct alternate_object_database *alt;
1314
1315         fd = git_open_noatime(name);
1316         if (fd >= 0)
1317                 return fd;
1318
1319         prepare_alt_odb();
1320         errno = ENOENT;
1321         for (alt = alt_odb_list; alt; alt = alt->next) {
1322                 name = alt->name;
1323                 fill_sha1_path(name, sha1);
1324                 fd = git_open_noatime(alt->base);
1325                 if (fd >= 0)
1326                         return fd;
1327         }
1328         return -1;
1329 }
1330
1331 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1332 {
1333         void *map;
1334         int fd;
1335
1336         fd = open_sha1_file(sha1);
1337         map = NULL;
1338         if (fd >= 0) {
1339                 struct stat st;
1340
1341                 if (!fstat(fd, &st)) {
1342                         *size = xsize_t(st.st_size);
1343                         if (!*size) {
1344                                 /* mmap() is forbidden on empty files */
1345                                 error("object file %s is empty", sha1_file_name(sha1));
1346                                 return NULL;
1347                         }
1348                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1349                 }
1350                 close(fd);
1351         }
1352         return map;
1353 }
1354
1355 /*
1356  * There used to be a second loose object header format which
1357  * was meant to mimic the in-pack format, allowing for direct
1358  * copy of the object data.  This format turned up not to be
1359  * really worth it and we no longer write loose objects in that
1360  * format.
1361  */
1362 static int experimental_loose_object(unsigned char *map)
1363 {
1364         unsigned int word;
1365
1366         /*
1367          * We must determine if the buffer contains the standard
1368          * zlib-deflated stream or the experimental format based
1369          * on the in-pack object format. Compare the header byte
1370          * for each format:
1371          *
1372          * RFC1950 zlib w/ deflate : 0www1000 : 0 <= www <= 7
1373          * Experimental pack-based : Stttssss : ttt = 1,2,3,4
1374          *
1375          * If bit 7 is clear and bits 0-3 equal 8, the buffer MUST be
1376          * in standard loose-object format, UNLESS it is a Git-pack
1377          * format object *exactly* 8 bytes in size when inflated.
1378          *
1379          * However, RFC1950 also specifies that the 1st 16-bit word
1380          * must be divisible by 31 - this checksum tells us our buffer
1381          * is in the standard format, giving a false positive only if
1382          * the 1st word of the Git-pack format object happens to be
1383          * divisible by 31, ie:
1384          *      ((byte0 * 256) + byte1) % 31 = 0
1385          *   =>        0ttt10000www1000 % 31 = 0
1386          *
1387          * As it happens, this case can only arise for www=3 & ttt=1
1388          * - ie, a Commit object, which would have to be 8 bytes in
1389          * size. As no Commit can be that small, we find that the
1390          * combination of these two criteria (bitmask & checksum)
1391          * can always correctly determine the buffer format.
1392          */
1393         word = (map[0] << 8) + map[1];
1394         if ((map[0] & 0x8F) == 0x08 && !(word % 31))
1395                 return 0;
1396         else
1397                 return 1;
1398 }
1399
1400 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1401                 unsigned long len, enum object_type *type, unsigned long *sizep)
1402 {
1403         unsigned shift;
1404         unsigned long size, c;
1405         unsigned long used = 0;
1406
1407         c = buf[used++];
1408         *type = (c >> 4) & 7;
1409         size = c & 15;
1410         shift = 4;
1411         while (c & 0x80) {
1412                 if (len <= used || bitsizeof(long) <= shift) {
1413                         error("bad object header");
1414                         size = used = 0;
1415                         break;
1416                 }
1417                 c = buf[used++];
1418                 size += (c & 0x7f) << shift;
1419                 shift += 7;
1420         }
1421         *sizep = size;
1422         return used;
1423 }
1424
1425 int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1426 {
1427         unsigned long size, used;
1428         static const char valid_loose_object_type[8] = {
1429                 0, /* OBJ_EXT */
1430                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1431                 0, /* "delta" and others are invalid in a loose object */
1432         };
1433         enum object_type type;
1434
1435         /* Get the data stream */
1436         memset(stream, 0, sizeof(*stream));
1437         stream->next_in = map;
1438         stream->avail_in = mapsize;
1439         stream->next_out = buffer;
1440         stream->avail_out = bufsiz;
1441
1442         if (experimental_loose_object(map)) {
1443                 /*
1444                  * The old experimental format we no longer produce;
1445                  * we can still read it.
1446                  */
1447                 used = unpack_object_header_buffer(map, mapsize, &type, &size);
1448                 if (!used || !valid_loose_object_type[type])
1449                         return -1;
1450                 map += used;
1451                 mapsize -= used;
1452
1453                 /* Set up the stream for the rest.. */
1454                 stream->next_in = map;
1455                 stream->avail_in = mapsize;
1456                 git_inflate_init(stream);
1457
1458                 /* And generate the fake traditional header */
1459                 stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1460                                                  typename(type), size);
1461                 return 0;
1462         }
1463         git_inflate_init(stream);
1464         return git_inflate(stream, 0);
1465 }
1466
1467 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1468 {
1469         int bytes = strlen(buffer) + 1;
1470         unsigned char *buf = xmallocz(size);
1471         unsigned long n;
1472         int status = Z_OK;
1473
1474         n = stream->total_out - bytes;
1475         if (n > size)
1476                 n = size;
1477         memcpy(buf, (char *) buffer + bytes, n);
1478         bytes = n;
1479         if (bytes <= size) {
1480                 /*
1481                  * The above condition must be (bytes <= size), not
1482                  * (bytes < size).  In other words, even though we
1483                  * expect no more output and set avail_out to zero,
1484                  * the input zlib stream may have bytes that express
1485                  * "this concludes the stream", and we *do* want to
1486                  * eat that input.
1487                  *
1488                  * Otherwise we would not be able to test that we
1489                  * consumed all the input to reach the expected size;
1490                  * we also want to check that zlib tells us that all
1491                  * went well with status == Z_STREAM_END at the end.
1492                  */
1493                 stream->next_out = buf + bytes;
1494                 stream->avail_out = size - bytes;
1495                 while (status == Z_OK)
1496                         status = git_inflate(stream, Z_FINISH);
1497         }
1498         if (status == Z_STREAM_END && !stream->avail_in) {
1499                 git_inflate_end(stream);
1500                 return buf;
1501         }
1502
1503         if (status < 0)
1504                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1505         else if (stream->avail_in)
1506                 error("garbage at end of loose object '%s'",
1507                       sha1_to_hex(sha1));
1508         free(buf);
1509         return NULL;
1510 }
1511
1512 /*
1513  * We used to just use "sscanf()", but that's actually way
1514  * too permissive for what we want to check. So do an anal
1515  * object header parse by hand.
1516  */
1517 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1518 {
1519         char type[10];
1520         int i;
1521         unsigned long size;
1522
1523         /*
1524          * The type can be at most ten bytes (including the
1525          * terminating '\0' that we add), and is followed by
1526          * a space.
1527          */
1528         i = 0;
1529         for (;;) {
1530                 char c = *hdr++;
1531                 if (c == ' ')
1532                         break;
1533                 type[i++] = c;
1534                 if (i >= sizeof(type))
1535                         return -1;
1536         }
1537         type[i] = 0;
1538
1539         /*
1540          * The length must follow immediately, and be in canonical
1541          * decimal format (ie "010" is not valid).
1542          */
1543         size = *hdr++ - '0';
1544         if (size > 9)
1545                 return -1;
1546         if (size) {
1547                 for (;;) {
1548                         unsigned long c = *hdr - '0';
1549                         if (c > 9)
1550                                 break;
1551                         hdr++;
1552                         size = size * 10 + c;
1553                 }
1554         }
1555         *sizep = size;
1556
1557         /*
1558          * The length must be followed by a zero byte
1559          */
1560         return *hdr ? -1 : type_from_string(type);
1561 }
1562
1563 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1564 {
1565         int ret;
1566         git_zstream stream;
1567         char hdr[8192];
1568
1569         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1570         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1571                 return NULL;
1572
1573         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1574 }
1575
1576 unsigned long get_size_from_delta(struct packed_git *p,
1577                                   struct pack_window **w_curs,
1578                                   off_t curpos)
1579 {
1580         const unsigned char *data;
1581         unsigned char delta_head[20], *in;
1582         git_zstream stream;
1583         int st;
1584
1585         memset(&stream, 0, sizeof(stream));
1586         stream.next_out = delta_head;
1587         stream.avail_out = sizeof(delta_head);
1588
1589         git_inflate_init(&stream);
1590         do {
1591                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1592                 stream.next_in = in;
1593                 st = git_inflate(&stream, Z_FINISH);
1594                 curpos += stream.next_in - in;
1595         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1596                  stream.total_out < sizeof(delta_head));
1597         git_inflate_end(&stream);
1598         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1599                 error("delta data unpack-initial failed");
1600                 return 0;
1601         }
1602
1603         /* Examine the initial part of the delta to figure out
1604          * the result size.
1605          */
1606         data = delta_head;
1607
1608         /* ignore base size */
1609         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1610
1611         /* Read the result size */
1612         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1613 }
1614
1615 static off_t get_delta_base(struct packed_git *p,
1616                                     struct pack_window **w_curs,
1617                                     off_t *curpos,
1618                                     enum object_type type,
1619                                     off_t delta_obj_offset)
1620 {
1621         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1622         off_t base_offset;
1623
1624         /* use_pack() assured us we have [base_info, base_info + 20)
1625          * as a range that we can look at without walking off the
1626          * end of the mapped window.  Its actually the hash size
1627          * that is assured.  An OFS_DELTA longer than the hash size
1628          * is stupid, as then a REF_DELTA would be smaller to store.
1629          */
1630         if (type == OBJ_OFS_DELTA) {
1631                 unsigned used = 0;
1632                 unsigned char c = base_info[used++];
1633                 base_offset = c & 127;
1634                 while (c & 128) {
1635                         base_offset += 1;
1636                         if (!base_offset || MSB(base_offset, 7))
1637                                 return 0;  /* overflow */
1638                         c = base_info[used++];
1639                         base_offset = (base_offset << 7) + (c & 127);
1640                 }
1641                 base_offset = delta_obj_offset - base_offset;
1642                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1643                         return 0;  /* out of bound */
1644                 *curpos += used;
1645         } else if (type == OBJ_REF_DELTA) {
1646                 /* The base entry _must_ be in the same pack */
1647                 base_offset = find_pack_entry_one(base_info, p);
1648                 *curpos += 20;
1649         } else
1650                 die("I am totally screwed");
1651         return base_offset;
1652 }
1653
1654 int unpack_object_header(struct packed_git *p,
1655                          struct pack_window **w_curs,
1656                          off_t *curpos,
1657                          unsigned long *sizep)
1658 {
1659         unsigned char *base;
1660         unsigned long left;
1661         unsigned long used;
1662         enum object_type type;
1663
1664         /* use_pack() assures us we have [base, base + 20) available
1665          * as a range that we can look at.  (Its actually the hash
1666          * size that is assured.)  With our object header encoding
1667          * the maximum deflated object size is 2^137, which is just
1668          * insane, so we know won't exceed what we have been given.
1669          */
1670         base = use_pack(p, w_curs, *curpos, &left);
1671         used = unpack_object_header_buffer(base, left, &type, sizep);
1672         if (!used) {
1673                 type = OBJ_BAD;
1674         } else
1675                 *curpos += used;
1676
1677         return type;
1678 }
1679
1680 static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1681 {
1682         int type;
1683         struct revindex_entry *revidx;
1684         const unsigned char *sha1;
1685         revidx = find_pack_revindex(p, obj_offset);
1686         if (!revidx)
1687                 return OBJ_BAD;
1688         sha1 = nth_packed_object_sha1(p, revidx->nr);
1689         mark_bad_packed_object(p, sha1);
1690         type = sha1_object_info(sha1, NULL);
1691         if (type <= OBJ_NONE)
1692                 return OBJ_BAD;
1693         return type;
1694 }
1695
1696
1697 #define POI_STACK_PREALLOC 64
1698
1699 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1700                               unsigned long *sizep, int *rtype)
1701 {
1702         struct pack_window *w_curs = NULL;
1703         unsigned long size;
1704         off_t curpos = obj_offset;
1705         enum object_type type;
1706         off_t small_poi_stack[POI_STACK_PREALLOC];
1707         off_t *poi_stack = small_poi_stack;
1708         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1709
1710         type = unpack_object_header(p, &w_curs, &curpos, &size);
1711
1712         if (rtype)
1713                 *rtype = type; /* representation type */
1714
1715         if (sizep) {
1716                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1717                         off_t tmp_pos = curpos;
1718                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1719                                                            type, obj_offset);
1720                         if (!base_offset) {
1721                                 type = OBJ_BAD;
1722                                 goto out;
1723                         }
1724                         *sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1725                         if (*sizep == 0) {
1726                                 type = OBJ_BAD;
1727                                 goto out;
1728                         }
1729                 } else {
1730                         *sizep = size;
1731                 }
1732         }
1733
1734         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1735                 off_t base_offset;
1736                 /* Push the object we're going to leave behind */
1737                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1738                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1739                         poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
1740                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1741                 } else {
1742                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1743                 }
1744                 poi_stack[poi_stack_nr++] = obj_offset;
1745                 /* If parsing the base offset fails, just unwind */
1746                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1747                 if (!base_offset)
1748                         goto unwind;
1749                 curpos = obj_offset = base_offset;
1750                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1751                 if (type <= OBJ_NONE) {
1752                         /* If getting the base itself fails, we first
1753                          * retry the base, otherwise unwind */
1754                         type = retry_bad_packed_offset(p, base_offset);
1755                         if (type > OBJ_NONE)
1756                                 goto out;
1757                         goto unwind;
1758                 }
1759         }
1760
1761         switch (type) {
1762         case OBJ_BAD:
1763         case OBJ_COMMIT:
1764         case OBJ_TREE:
1765         case OBJ_BLOB:
1766         case OBJ_TAG:
1767                 break;
1768         default:
1769                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1770                       type, (uintmax_t)obj_offset, p->pack_name);
1771                 type = OBJ_BAD;
1772         }
1773
1774 out:
1775         if (poi_stack != small_poi_stack)
1776                 free(poi_stack);
1777         unuse_pack(&w_curs);
1778         return type;
1779
1780 unwind:
1781         while (poi_stack_nr) {
1782                 obj_offset = poi_stack[--poi_stack_nr];
1783                 type = retry_bad_packed_offset(p, obj_offset);
1784                 if (type > OBJ_NONE)
1785                         goto out;
1786         }
1787         type = OBJ_BAD;
1788         goto out;
1789 }
1790
1791 static void *unpack_compressed_entry(struct packed_git *p,
1792                                     struct pack_window **w_curs,
1793                                     off_t curpos,
1794                                     unsigned long size)
1795 {
1796         int st;
1797         git_zstream stream;
1798         unsigned char *buffer, *in;
1799
1800         buffer = xmallocz(size);
1801         memset(&stream, 0, sizeof(stream));
1802         stream.next_out = buffer;
1803         stream.avail_out = size + 1;
1804
1805         git_inflate_init(&stream);
1806         do {
1807                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1808                 stream.next_in = in;
1809                 st = git_inflate(&stream, Z_FINISH);
1810                 if (!stream.avail_out)
1811                         break; /* the payload is larger than it should be */
1812                 curpos += stream.next_in - in;
1813         } while (st == Z_OK || st == Z_BUF_ERROR);
1814         git_inflate_end(&stream);
1815         if ((st != Z_STREAM_END) || stream.total_out != size) {
1816                 free(buffer);
1817                 return NULL;
1818         }
1819
1820         return buffer;
1821 }
1822
1823 #define MAX_DELTA_CACHE (256)
1824
1825 static size_t delta_base_cached;
1826
1827 static struct delta_base_cache_lru_list {
1828         struct delta_base_cache_lru_list *prev;
1829         struct delta_base_cache_lru_list *next;
1830 } delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1831
1832 static struct delta_base_cache_entry {
1833         struct delta_base_cache_lru_list lru;
1834         void *data;
1835         struct packed_git *p;
1836         off_t base_offset;
1837         unsigned long size;
1838         enum object_type type;
1839 } delta_base_cache[MAX_DELTA_CACHE];
1840
1841 static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1842 {
1843         unsigned long hash;
1844
1845         hash = (unsigned long)p + (unsigned long)base_offset;
1846         hash += (hash >> 8) + (hash >> 16);
1847         return hash % MAX_DELTA_CACHE;
1848 }
1849
1850 static struct delta_base_cache_entry *
1851 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1852 {
1853         unsigned long hash = pack_entry_hash(p, base_offset);
1854         return delta_base_cache + hash;
1855 }
1856
1857 static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
1858                                      struct packed_git *p, off_t base_offset)
1859 {
1860         return (ent->data && ent->p == p && ent->base_offset == base_offset);
1861 }
1862
1863 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1864 {
1865         struct delta_base_cache_entry *ent;
1866         ent = get_delta_base_cache_entry(p, base_offset);
1867         return eq_delta_base_cache_entry(ent, p, base_offset);
1868 }
1869
1870 static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1871 {
1872         ent->data = NULL;
1873         ent->lru.next->prev = ent->lru.prev;
1874         ent->lru.prev->next = ent->lru.next;
1875         delta_base_cached -= ent->size;
1876 }
1877
1878 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1879         unsigned long *base_size, enum object_type *type, int keep_cache)
1880 {
1881         struct delta_base_cache_entry *ent;
1882         void *ret;
1883
1884         ent = get_delta_base_cache_entry(p, base_offset);
1885
1886         if (!eq_delta_base_cache_entry(ent, p, base_offset))
1887                 return unpack_entry(p, base_offset, type, base_size);
1888
1889         ret = ent->data;
1890
1891         if (!keep_cache)
1892                 clear_delta_base_cache_entry(ent);
1893         else
1894                 ret = xmemdupz(ent->data, ent->size);
1895         *type = ent->type;
1896         *base_size = ent->size;
1897         return ret;
1898 }
1899
1900 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1901 {
1902         if (ent->data) {
1903                 free(ent->data);
1904                 ent->data = NULL;
1905                 ent->lru.next->prev = ent->lru.prev;
1906                 ent->lru.prev->next = ent->lru.next;
1907                 delta_base_cached -= ent->size;
1908         }
1909 }
1910
1911 void clear_delta_base_cache(void)
1912 {
1913         unsigned long p;
1914         for (p = 0; p < MAX_DELTA_CACHE; p++)
1915                 release_delta_base_cache(&delta_base_cache[p]);
1916 }
1917
1918 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1919         void *base, unsigned long base_size, enum object_type type)
1920 {
1921         unsigned long hash = pack_entry_hash(p, base_offset);
1922         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1923         struct delta_base_cache_lru_list *lru;
1924
1925         release_delta_base_cache(ent);
1926         delta_base_cached += base_size;
1927
1928         for (lru = delta_base_cache_lru.next;
1929              delta_base_cached > delta_base_cache_limit
1930              && lru != &delta_base_cache_lru;
1931              lru = lru->next) {
1932                 struct delta_base_cache_entry *f = (void *)lru;
1933                 if (f->type == OBJ_BLOB)
1934                         release_delta_base_cache(f);
1935         }
1936         for (lru = delta_base_cache_lru.next;
1937              delta_base_cached > delta_base_cache_limit
1938              && lru != &delta_base_cache_lru;
1939              lru = lru->next) {
1940                 struct delta_base_cache_entry *f = (void *)lru;
1941                 release_delta_base_cache(f);
1942         }
1943
1944         ent->p = p;
1945         ent->base_offset = base_offset;
1946         ent->type = type;
1947         ent->data = base;
1948         ent->size = base_size;
1949         ent->lru.next = &delta_base_cache_lru;
1950         ent->lru.prev = delta_base_cache_lru.prev;
1951         delta_base_cache_lru.prev->next = &ent->lru;
1952         delta_base_cache_lru.prev = &ent->lru;
1953 }
1954
1955 static void *read_object(const unsigned char *sha1, enum object_type *type,
1956                          unsigned long *size);
1957
1958 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1959 {
1960         static FILE *log_file;
1961
1962         if (!log_pack_access)
1963                 log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
1964         if (!log_pack_access)
1965                 log_pack_access = no_log_pack_access;
1966         if (log_pack_access == no_log_pack_access)
1967                 return;
1968
1969         if (!log_file) {
1970                 log_file = fopen(log_pack_access, "w");
1971                 if (!log_file) {
1972                         error("cannot open pack access log '%s' for writing: %s",
1973                               log_pack_access, strerror(errno));
1974                         log_pack_access = no_log_pack_access;
1975                         return;
1976                 }
1977         }
1978         fprintf(log_file, "%s %"PRIuMAX"\n",
1979                 p->pack_name, (uintmax_t)obj_offset);
1980         fflush(log_file);
1981 }
1982
1983 int do_check_packed_object_crc;
1984
1985 #define UNPACK_ENTRY_STACK_PREALLOC 64
1986 struct unpack_entry_stack_ent {
1987         off_t obj_offset;
1988         off_t curpos;
1989         unsigned long size;
1990 };
1991
1992 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1993                    enum object_type *final_type, unsigned long *final_size)
1994 {
1995         struct pack_window *w_curs = NULL;
1996         off_t curpos = obj_offset;
1997         void *data = NULL;
1998         unsigned long size;
1999         enum object_type type;
2000         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2001         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2002         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2003         int base_from_cache = 0;
2004
2005         if (log_pack_access != no_log_pack_access)
2006                 write_pack_access_log(p, obj_offset);
2007
2008         /* PHASE 1: drill down to the innermost base object */
2009         for (;;) {
2010                 off_t base_offset;
2011                 int i;
2012                 struct delta_base_cache_entry *ent;
2013
2014                 if (do_check_packed_object_crc && p->index_version > 1) {
2015                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2016                         unsigned long len = revidx[1].offset - obj_offset;
2017                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2018                                 const unsigned char *sha1 =
2019                                         nth_packed_object_sha1(p, revidx->nr);
2020                                 error("bad packed object CRC for %s",
2021                                       sha1_to_hex(sha1));
2022                                 mark_bad_packed_object(p, sha1);
2023                                 unuse_pack(&w_curs);
2024                                 return NULL;
2025                         }
2026                 }
2027
2028                 ent = get_delta_base_cache_entry(p, curpos);
2029                 if (eq_delta_base_cache_entry(ent, p, curpos)) {
2030                         type = ent->type;
2031                         data = ent->data;
2032                         size = ent->size;
2033                         clear_delta_base_cache_entry(ent);
2034                         base_from_cache = 1;
2035                         break;
2036                 }
2037
2038                 type = unpack_object_header(p, &w_curs, &curpos, &size);
2039                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2040                         break;
2041
2042                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2043                 if (!base_offset) {
2044                         error("failed to validate delta base reference "
2045                               "at offset %"PRIuMAX" from %s",
2046                               (uintmax_t)curpos, p->pack_name);
2047                         /* bail to phase 2, in hopes of recovery */
2048                         data = NULL;
2049                         break;
2050                 }
2051
2052                 /* push object, proceed to base */
2053                 if (delta_stack_nr >= delta_stack_alloc
2054                     && delta_stack == small_delta_stack) {
2055                         delta_stack_alloc = alloc_nr(delta_stack_nr);
2056                         delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
2057                         memcpy(delta_stack, small_delta_stack,
2058                                sizeof(*delta_stack)*delta_stack_nr);
2059                 } else {
2060                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2061                 }
2062                 i = delta_stack_nr++;
2063                 delta_stack[i].obj_offset = obj_offset;
2064                 delta_stack[i].curpos = curpos;
2065                 delta_stack[i].size = size;
2066
2067                 curpos = obj_offset = base_offset;
2068         }
2069
2070         /* PHASE 2: handle the base */
2071         switch (type) {
2072         case OBJ_OFS_DELTA:
2073         case OBJ_REF_DELTA:
2074                 if (data)
2075                         die("BUG in unpack_entry: left loop at a valid delta");
2076                 break;
2077         case OBJ_COMMIT:
2078         case OBJ_TREE:
2079         case OBJ_BLOB:
2080         case OBJ_TAG:
2081                 if (!base_from_cache)
2082                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
2083                 break;
2084         default:
2085                 data = NULL;
2086                 error("unknown object type %i at offset %"PRIuMAX" in %s",
2087                       type, (uintmax_t)obj_offset, p->pack_name);
2088         }
2089
2090         /* PHASE 3: apply deltas in order */
2091
2092         /* invariants:
2093          *   'data' holds the base data, or NULL if there was corruption
2094          */
2095         while (delta_stack_nr) {
2096                 void *delta_data;
2097                 void *base = data;
2098                 unsigned long delta_size, base_size = size;
2099                 int i;
2100
2101                 data = NULL;
2102
2103                 if (base)
2104                         add_delta_base_cache(p, obj_offset, base, base_size, type);
2105
2106                 if (!base) {
2107                         /*
2108                          * We're probably in deep shit, but let's try to fetch
2109                          * the required base anyway from another pack or loose.
2110                          * This is costly but should happen only in the presence
2111                          * of a corrupted pack, and is better than failing outright.
2112                          */
2113                         struct revindex_entry *revidx;
2114                         const unsigned char *base_sha1;
2115                         revidx = find_pack_revindex(p, obj_offset);
2116                         if (revidx) {
2117                                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2118                                 error("failed to read delta base object %s"
2119                                       " at offset %"PRIuMAX" from %s",
2120                                       sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2121                                       p->pack_name);
2122                                 mark_bad_packed_object(p, base_sha1);
2123                                 base = read_object(base_sha1, &type, &base_size);
2124                         }
2125                 }
2126
2127                 i = --delta_stack_nr;
2128                 obj_offset = delta_stack[i].obj_offset;
2129                 curpos = delta_stack[i].curpos;
2130                 delta_size = delta_stack[i].size;
2131
2132                 if (!base)
2133                         continue;
2134
2135                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2136
2137                 if (!delta_data) {
2138                         error("failed to unpack compressed delta "
2139                               "at offset %"PRIuMAX" from %s",
2140                               (uintmax_t)curpos, p->pack_name);
2141                         data = NULL;
2142                         continue;
2143                 }
2144
2145                 data = patch_delta(base, base_size,
2146                                    delta_data, delta_size,
2147                                    &size);
2148
2149                 /*
2150                  * We could not apply the delta; warn the user, but keep going.
2151                  * Our failure will be noticed either in the next iteration of
2152                  * the loop, or if this is the final delta, in the caller when
2153                  * we return NULL. Those code paths will take care of making
2154                  * a more explicit warning and retrying with another copy of
2155                  * the object.
2156                  */
2157                 if (!data)
2158                         error("failed to apply delta");
2159
2160                 free(delta_data);
2161         }
2162
2163         *final_type = type;
2164         *final_size = size;
2165
2166         unuse_pack(&w_curs);
2167         return data;
2168 }
2169
2170 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2171                                             uint32_t n)
2172 {
2173         const unsigned char *index = p->index_data;
2174         if (!index) {
2175                 if (open_pack_index(p))
2176                         return NULL;
2177                 index = p->index_data;
2178         }
2179         if (n >= p->num_objects)
2180                 return NULL;
2181         index += 4 * 256;
2182         if (p->index_version == 1) {
2183                 return index + 24 * n + 4;
2184         } else {
2185                 index += 8;
2186                 return index + 20 * n;
2187         }
2188 }
2189
2190 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2191 {
2192         const unsigned char *index = p->index_data;
2193         index += 4 * 256;
2194         if (p->index_version == 1) {
2195                 return ntohl(*((uint32_t *)(index + 24 * n)));
2196         } else {
2197                 uint32_t off;
2198                 index += 8 + p->num_objects * (20 + 4);
2199                 off = ntohl(*((uint32_t *)(index + 4 * n)));
2200                 if (!(off & 0x80000000))
2201                         return off;
2202                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2203                 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2204                                    ntohl(*((uint32_t *)(index + 4)));
2205         }
2206 }
2207
2208 off_t find_pack_entry_one(const unsigned char *sha1,
2209                                   struct packed_git *p)
2210 {
2211         const uint32_t *level1_ofs = p->index_data;
2212         const unsigned char *index = p->index_data;
2213         unsigned hi, lo, stride;
2214         static int use_lookup = -1;
2215         static int debug_lookup = -1;
2216
2217         if (debug_lookup < 0)
2218                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2219
2220         if (!index) {
2221                 if (open_pack_index(p))
2222                         return 0;
2223                 level1_ofs = p->index_data;
2224                 index = p->index_data;
2225         }
2226         if (p->index_version > 1) {
2227                 level1_ofs += 2;
2228                 index += 8;
2229         }
2230         index += 4 * 256;
2231         hi = ntohl(level1_ofs[*sha1]);
2232         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2233         if (p->index_version > 1) {
2234                 stride = 20;
2235         } else {
2236                 stride = 24;
2237                 index += 4;
2238         }
2239
2240         if (debug_lookup)
2241                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2242                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2243
2244         if (use_lookup < 0)
2245                 use_lookup = !!getenv("GIT_USE_LOOKUP");
2246         if (use_lookup) {
2247                 int pos = sha1_entry_pos(index, stride, 0,
2248                                          lo, hi, p->num_objects, sha1);
2249                 if (pos < 0)
2250                         return 0;
2251                 return nth_packed_object_offset(p, pos);
2252         }
2253
2254         do {
2255                 unsigned mi = (lo + hi) / 2;
2256                 int cmp = hashcmp(index + mi * stride, sha1);
2257
2258                 if (debug_lookup)
2259                         printf("lo %u hi %u rg %u mi %u\n",
2260                                lo, hi, hi - lo, mi);
2261                 if (!cmp)
2262                         return nth_packed_object_offset(p, mi);
2263                 if (cmp > 0)
2264                         hi = mi;
2265                 else
2266                         lo = mi+1;
2267         } while (lo < hi);
2268         return 0;
2269 }
2270
2271 int is_pack_valid(struct packed_git *p)
2272 {
2273         /* An already open pack is known to be valid. */
2274         if (p->pack_fd != -1)
2275                 return 1;
2276
2277         /* If the pack has one window completely covering the
2278          * file size, the pack is known to be valid even if
2279          * the descriptor is not currently open.
2280          */
2281         if (p->windows) {
2282                 struct pack_window *w = p->windows;
2283
2284                 if (!w->offset && w->len == p->pack_size)
2285                         return 1;
2286         }
2287
2288         /* Force the pack to open to prove its valid. */
2289         return !open_packed_git(p);
2290 }
2291
2292 static int fill_pack_entry(const unsigned char *sha1,
2293                            struct pack_entry *e,
2294                            struct packed_git *p)
2295 {
2296         off_t offset;
2297
2298         if (p->num_bad_objects) {
2299                 unsigned i;
2300                 for (i = 0; i < p->num_bad_objects; i++)
2301                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2302                                 return 0;
2303         }
2304
2305         offset = find_pack_entry_one(sha1, p);
2306         if (!offset)
2307                 return 0;
2308
2309         /*
2310          * We are about to tell the caller where they can locate the
2311          * requested object.  We better make sure the packfile is
2312          * still here and can be accessed before supplying that
2313          * answer, as it may have been deleted since the index was
2314          * loaded!
2315          */
2316         if (!is_pack_valid(p)) {
2317                 warning("packfile %s cannot be accessed", p->pack_name);
2318                 return 0;
2319         }
2320         e->offset = offset;
2321         e->p = p;
2322         hashcpy(e->sha1, sha1);
2323         return 1;
2324 }
2325
2326 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2327 {
2328         struct packed_git *p;
2329
2330         prepare_packed_git();
2331         if (!packed_git)
2332                 return 0;
2333
2334         if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2335                 return 1;
2336
2337         for (p = packed_git; p; p = p->next) {
2338                 if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
2339                         continue;
2340
2341                 last_found_pack = p;
2342                 return 1;
2343         }
2344         return 0;
2345 }
2346
2347 struct packed_git *find_sha1_pack(const unsigned char *sha1,
2348                                   struct packed_git *packs)
2349 {
2350         struct packed_git *p;
2351
2352         for (p = packs; p; p = p->next) {
2353                 if (find_pack_entry_one(sha1, p))
2354                         return p;
2355         }
2356         return NULL;
2357
2358 }
2359
2360 static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
2361 {
2362         int status;
2363         unsigned long mapsize, size;
2364         void *map;
2365         git_zstream stream;
2366         char hdr[32];
2367
2368         map = map_sha1_file(sha1, &mapsize);
2369         if (!map)
2370                 return -1;
2371         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2372                 status = error("unable to unpack %s header",
2373                                sha1_to_hex(sha1));
2374         else if ((status = parse_sha1_header(hdr, &size)) < 0)
2375                 status = error("unable to parse %s header", sha1_to_hex(sha1));
2376         else if (sizep)
2377                 *sizep = size;
2378         git_inflate_end(&stream);
2379         munmap(map, mapsize);
2380         return status;
2381 }
2382
2383 /* returns enum object_type or negative */
2384 int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
2385 {
2386         struct cached_object *co;
2387         struct pack_entry e;
2388         int status, rtype;
2389
2390         co = find_cached_object(sha1);
2391         if (co) {
2392                 if (oi->sizep)
2393                         *(oi->sizep) = co->size;
2394                 oi->whence = OI_CACHED;
2395                 return co->type;
2396         }
2397
2398         if (!find_pack_entry(sha1, &e)) {
2399                 /* Most likely it's a loose object. */
2400                 status = sha1_loose_object_info(sha1, oi->sizep);
2401                 if (status >= 0) {
2402                         oi->whence = OI_LOOSE;
2403                         return status;
2404                 }
2405
2406                 /* Not a loose object; someone else may have just packed it. */
2407                 reprepare_packed_git();
2408                 if (!find_pack_entry(sha1, &e))
2409                         return status;
2410         }
2411
2412         status = packed_object_info(e.p, e.offset, oi->sizep, &rtype);
2413         if (status < 0) {
2414                 mark_bad_packed_object(e.p, sha1);
2415                 status = sha1_object_info_extended(sha1, oi);
2416         } else if (in_delta_base_cache(e.p, e.offset)) {
2417                 oi->whence = OI_DBCACHED;
2418         } else {
2419                 oi->whence = OI_PACKED;
2420                 oi->u.packed.offset = e.offset;
2421                 oi->u.packed.pack = e.p;
2422                 oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2423                                          rtype == OBJ_OFS_DELTA);
2424         }
2425
2426         return status;
2427 }
2428
2429 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2430 {
2431         struct object_info oi;
2432
2433         oi.sizep = sizep;
2434         return sha1_object_info_extended(sha1, &oi);
2435 }
2436
2437 static void *read_packed_sha1(const unsigned char *sha1,
2438                               enum object_type *type, unsigned long *size)
2439 {
2440         struct pack_entry e;
2441         void *data;
2442
2443         if (!find_pack_entry(sha1, &e))
2444                 return NULL;
2445         data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2446         if (!data) {
2447                 /*
2448                  * We're probably in deep shit, but let's try to fetch
2449                  * the required object anyway from another pack or loose.
2450                  * This should happen only in the presence of a corrupted
2451                  * pack, and is better than failing outright.
2452                  */
2453                 error("failed to read object %s at offset %"PRIuMAX" from %s",
2454                       sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2455                 mark_bad_packed_object(e.p, sha1);
2456                 data = read_object(sha1, type, size);
2457         }
2458         return data;
2459 }
2460
2461 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2462                       unsigned char *sha1)
2463 {
2464         struct cached_object *co;
2465
2466         hash_sha1_file(buf, len, typename(type), sha1);
2467         if (has_sha1_file(sha1) || find_cached_object(sha1))
2468                 return 0;
2469         if (cached_object_alloc <= cached_object_nr) {
2470                 cached_object_alloc = alloc_nr(cached_object_alloc);
2471                 cached_objects = xrealloc(cached_objects,
2472                                           sizeof(*cached_objects) *
2473                                           cached_object_alloc);
2474         }
2475         co = &cached_objects[cached_object_nr++];
2476         co->size = len;
2477         co->type = type;
2478         co->buf = xmalloc(len);
2479         memcpy(co->buf, buf, len);
2480         hashcpy(co->sha1, sha1);
2481         return 0;
2482 }
2483
2484 static void *read_object(const unsigned char *sha1, enum object_type *type,
2485                          unsigned long *size)
2486 {
2487         unsigned long mapsize;
2488         void *map, *buf;
2489         struct cached_object *co;
2490
2491         co = find_cached_object(sha1);
2492         if (co) {
2493                 *type = co->type;
2494                 *size = co->size;
2495                 return xmemdupz(co->buf, co->size);
2496         }
2497
2498         buf = read_packed_sha1(sha1, type, size);
2499         if (buf)
2500                 return buf;
2501         map = map_sha1_file(sha1, &mapsize);
2502         if (map) {
2503                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2504                 munmap(map, mapsize);
2505                 return buf;
2506         }
2507         reprepare_packed_git();
2508         return read_packed_sha1(sha1, type, size);
2509 }
2510
2511 /*
2512  * This function dies on corrupt objects; the callers who want to
2513  * deal with them should arrange to call read_object() and give error
2514  * messages themselves.
2515  */
2516 void *read_sha1_file_extended(const unsigned char *sha1,
2517                               enum object_type *type,
2518                               unsigned long *size,
2519                               unsigned flag)
2520 {
2521         void *data;
2522         char *path;
2523         const struct packed_git *p;
2524         const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
2525                 ? lookup_replace_object(sha1) : sha1;
2526
2527         errno = 0;
2528         data = read_object(repl, type, size);
2529         if (data)
2530                 return data;
2531
2532         if (errno && errno != ENOENT)
2533                 die_errno("failed to read object %s", sha1_to_hex(sha1));
2534
2535         /* die if we replaced an object with one that does not exist */
2536         if (repl != sha1)
2537                 die("replacement %s not found for %s",
2538                     sha1_to_hex(repl), sha1_to_hex(sha1));
2539
2540         if (has_loose_object(repl)) {
2541                 path = sha1_file_name(sha1);
2542                 die("loose object %s (stored in %s) is corrupt",
2543                     sha1_to_hex(repl), path);
2544         }
2545
2546         if ((p = has_packed_and_bad(repl)) != NULL)
2547                 die("packed object %s (stored in %s) is corrupt",
2548                     sha1_to_hex(repl), p->pack_name);
2549
2550         return NULL;
2551 }
2552
2553 void *read_object_with_reference(const unsigned char *sha1,
2554                                  const char *required_type_name,
2555                                  unsigned long *size,
2556                                  unsigned char *actual_sha1_return)
2557 {
2558         enum object_type type, required_type;
2559         void *buffer;
2560         unsigned long isize;
2561         unsigned char actual_sha1[20];
2562
2563         required_type = type_from_string(required_type_name);
2564         hashcpy(actual_sha1, sha1);
2565         while (1) {
2566                 int ref_length = -1;
2567                 const char *ref_type = NULL;
2568
2569                 buffer = read_sha1_file(actual_sha1, &type, &isize);
2570                 if (!buffer)
2571                         return NULL;
2572                 if (type == required_type) {
2573                         *size = isize;
2574                         if (actual_sha1_return)
2575                                 hashcpy(actual_sha1_return, actual_sha1);
2576                         return buffer;
2577                 }
2578                 /* Handle references */
2579                 else if (type == OBJ_COMMIT)
2580                         ref_type = "tree ";
2581                 else if (type == OBJ_TAG)
2582                         ref_type = "object ";
2583                 else {
2584                         free(buffer);
2585                         return NULL;
2586                 }
2587                 ref_length = strlen(ref_type);
2588
2589                 if (ref_length + 40 > isize ||
2590                     memcmp(buffer, ref_type, ref_length) ||
2591                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2592                         free(buffer);
2593                         return NULL;
2594                 }
2595                 free(buffer);
2596                 /* Now we have the ID of the referred-to object in
2597                  * actual_sha1.  Check again. */
2598         }
2599 }
2600
2601 static void write_sha1_file_prepare(const void *buf, unsigned long len,
2602                                     const char *type, unsigned char *sha1,
2603                                     char *hdr, int *hdrlen)
2604 {
2605         git_SHA_CTX c;
2606
2607         /* Generate the header */
2608         *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2609
2610         /* Sha1.. */
2611         git_SHA1_Init(&c);
2612         git_SHA1_Update(&c, hdr, *hdrlen);
2613         git_SHA1_Update(&c, buf, len);
2614         git_SHA1_Final(sha1, &c);
2615 }
2616
2617 /*
2618  * Move the just written object into its final resting place.
2619  * NEEDSWORK: this should be renamed to finalize_temp_file() as
2620  * "moving" is only a part of what it does, when no patch between
2621  * master to pu changes the call sites of this function.
2622  */
2623 int move_temp_to_file(const char *tmpfile, const char *filename)
2624 {
2625         int ret = 0;
2626
2627         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2628                 goto try_rename;
2629         else if (link(tmpfile, filename))
2630                 ret = errno;
2631
2632         /*
2633          * Coda hack - coda doesn't like cross-directory links,
2634          * so we fall back to a rename, which will mean that it
2635          * won't be able to check collisions, but that's not a
2636          * big deal.
2637          *
2638          * The same holds for FAT formatted media.
2639          *
2640          * When this succeeds, we just return.  We have nothing
2641          * left to unlink.
2642          */
2643         if (ret && ret != EEXIST) {
2644         try_rename:
2645                 if (!rename(tmpfile, filename))
2646                         goto out;
2647                 ret = errno;
2648         }
2649         unlink_or_warn(tmpfile);
2650         if (ret) {
2651                 if (ret != EEXIST) {
2652                         return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
2653                 }
2654                 /* FIXME!!! Collision check here ? */
2655         }
2656
2657 out:
2658         if (adjust_shared_perm(filename))
2659                 return error("unable to set permission to '%s'", filename);
2660         return 0;
2661 }
2662
2663 static int write_buffer(int fd, const void *buf, size_t len)
2664 {
2665         if (write_in_full(fd, buf, len) < 0)
2666                 return error("file write error (%s)", strerror(errno));
2667         return 0;
2668 }
2669
2670 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2671                    unsigned char *sha1)
2672 {
2673         char hdr[32];
2674         int hdrlen;
2675         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2676         return 0;
2677 }
2678
2679 /* Finalize a file on disk, and close it. */
2680 static void close_sha1_file(int fd)
2681 {
2682         if (fsync_object_files)
2683                 fsync_or_die(fd, "sha1 file");
2684         if (close(fd) != 0)
2685                 die_errno("error when closing sha1 file");
2686 }
2687
2688 /* Size of directory component, including the ending '/' */
2689 static inline int directory_size(const char *filename)
2690 {
2691         const char *s = strrchr(filename, '/');
2692         if (!s)
2693                 return 0;
2694         return s - filename + 1;
2695 }
2696
2697 /*
2698  * This creates a temporary file in the same directory as the final
2699  * 'filename'
2700  *
2701  * We want to avoid cross-directory filename renames, because those
2702  * can have problems on various filesystems (FAT, NFS, Coda).
2703  */
2704 static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2705 {
2706         int fd, dirlen = directory_size(filename);
2707
2708         if (dirlen + 20 > bufsiz) {
2709                 errno = ENAMETOOLONG;
2710                 return -1;
2711         }
2712         memcpy(buffer, filename, dirlen);
2713         strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2714         fd = git_mkstemp_mode(buffer, 0444);
2715         if (fd < 0 && dirlen && errno == ENOENT) {
2716                 /* Make sure the directory exists */
2717                 memcpy(buffer, filename, dirlen);
2718                 buffer[dirlen-1] = 0;
2719                 if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2720                         return -1;
2721
2722                 /* Try again */
2723                 strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2724                 fd = git_mkstemp_mode(buffer, 0444);
2725         }
2726         return fd;
2727 }
2728
2729 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2730                               const void *buf, unsigned long len, time_t mtime)
2731 {
2732         int fd, ret;
2733         unsigned char compressed[4096];
2734         git_zstream stream;
2735         git_SHA_CTX c;
2736         unsigned char parano_sha1[20];
2737         char *filename;
2738         static char tmp_file[PATH_MAX];
2739
2740         filename = sha1_file_name(sha1);
2741         fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
2742         if (fd < 0) {
2743                 if (errno == EACCES)
2744                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
2745                 else
2746                         return error("unable to create temporary file: %s", strerror(errno));
2747         }
2748
2749         /* Set it up */
2750         memset(&stream, 0, sizeof(stream));
2751         git_deflate_init(&stream, zlib_compression_level);
2752         stream.next_out = compressed;
2753         stream.avail_out = sizeof(compressed);
2754         git_SHA1_Init(&c);
2755
2756         /* First header.. */
2757         stream.next_in = (unsigned char *)hdr;
2758         stream.avail_in = hdrlen;
2759         while (git_deflate(&stream, 0) == Z_OK)
2760                 ; /* nothing */
2761         git_SHA1_Update(&c, hdr, hdrlen);
2762
2763         /* Then the data itself.. */
2764         stream.next_in = (void *)buf;
2765         stream.avail_in = len;
2766         do {
2767                 unsigned char *in0 = stream.next_in;
2768                 ret = git_deflate(&stream, Z_FINISH);
2769                 git_SHA1_Update(&c, in0, stream.next_in - in0);
2770                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2771                         die("unable to write sha1 file");
2772                 stream.next_out = compressed;
2773                 stream.avail_out = sizeof(compressed);
2774         } while (ret == Z_OK);
2775
2776         if (ret != Z_STREAM_END)
2777                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2778         ret = git_deflate_end_gently(&stream);
2779         if (ret != Z_OK)
2780                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2781         git_SHA1_Final(parano_sha1, &c);
2782         if (hashcmp(sha1, parano_sha1) != 0)
2783                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2784
2785         close_sha1_file(fd);
2786
2787         if (mtime) {
2788                 struct utimbuf utb;
2789                 utb.actime = mtime;
2790                 utb.modtime = mtime;
2791                 if (utime(tmp_file, &utb) < 0)
2792                         warning("failed utime() on %s: %s",
2793                                 tmp_file, strerror(errno));
2794         }
2795
2796         return move_temp_to_file(tmp_file, filename);
2797 }
2798
2799 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2800 {
2801         unsigned char sha1[20];
2802         char hdr[32];
2803         int hdrlen;
2804
2805         /* Normally if we have it in the pack then we do not bother writing
2806          * it out into .git/objects/??/?{38} file.
2807          */
2808         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2809         if (returnsha1)
2810                 hashcpy(returnsha1, sha1);
2811         if (has_sha1_file(sha1))
2812                 return 0;
2813         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2814 }
2815
2816 int force_object_loose(const unsigned char *sha1, time_t mtime)
2817 {
2818         void *buf;
2819         unsigned long len;
2820         enum object_type type;
2821         char hdr[32];
2822         int hdrlen;
2823         int ret;
2824
2825         if (has_loose_object(sha1))
2826                 return 0;
2827         buf = read_packed_sha1(sha1, &type, &len);
2828         if (!buf)
2829                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2830         hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2831         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2832         free(buf);
2833
2834         return ret;
2835 }
2836
2837 int has_pack_index(const unsigned char *sha1)
2838 {
2839         struct stat st;
2840         if (stat(sha1_pack_index_name(sha1), &st))
2841                 return 0;
2842         return 1;
2843 }
2844
2845 int has_sha1_pack(const unsigned char *sha1)
2846 {
2847         struct pack_entry e;
2848         return find_pack_entry(sha1, &e);
2849 }
2850
2851 int has_sha1_file(const unsigned char *sha1)
2852 {
2853         struct pack_entry e;
2854
2855         if (find_pack_entry(sha1, &e))
2856                 return 1;
2857         return has_loose_object(sha1);
2858 }
2859
2860 static void check_tree(const void *buf, size_t size)
2861 {
2862         struct tree_desc desc;
2863         struct name_entry entry;
2864
2865         init_tree_desc(&desc, buf, size);
2866         while (tree_entry(&desc, &entry))
2867                 /* do nothing
2868                  * tree_entry() will die() on malformed entries */
2869                 ;
2870 }
2871
2872 static void check_commit(const void *buf, size_t size)
2873 {
2874         struct commit c;
2875         memset(&c, 0, sizeof(c));
2876         if (parse_commit_buffer(&c, buf, size))
2877                 die("corrupt commit");
2878 }
2879
2880 static void check_tag(const void *buf, size_t size)
2881 {
2882         struct tag t;
2883         memset(&t, 0, sizeof(t));
2884         if (parse_tag_buffer(&t, buf, size))
2885                 die("corrupt tag");
2886 }
2887
2888 static int index_mem(unsigned char *sha1, void *buf, size_t size,
2889                      enum object_type type,
2890                      const char *path, unsigned flags)
2891 {
2892         int ret, re_allocated = 0;
2893         int write_object = flags & HASH_WRITE_OBJECT;
2894
2895         if (!type)
2896                 type = OBJ_BLOB;
2897
2898         /*
2899          * Convert blobs to git internal format
2900          */
2901         if ((type == OBJ_BLOB) && path) {
2902                 struct strbuf nbuf = STRBUF_INIT;
2903                 if (convert_to_git(path, buf, size, &nbuf,
2904                                    write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
2905                         buf = strbuf_detach(&nbuf, &size);
2906                         re_allocated = 1;
2907                 }
2908         }
2909         if (flags & HASH_FORMAT_CHECK) {
2910                 if (type == OBJ_TREE)
2911                         check_tree(buf, size);
2912                 if (type == OBJ_COMMIT)
2913                         check_commit(buf, size);
2914                 if (type == OBJ_TAG)
2915                         check_tag(buf, size);
2916         }
2917
2918         if (write_object)
2919                 ret = write_sha1_file(buf, size, typename(type), sha1);
2920         else
2921                 ret = hash_sha1_file(buf, size, typename(type), sha1);
2922         if (re_allocated)
2923                 free(buf);
2924         return ret;
2925 }
2926
2927 static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
2928                       const char *path, unsigned flags)
2929 {
2930         struct strbuf sbuf = STRBUF_INIT;
2931         int ret;
2932
2933         if (strbuf_read(&sbuf, fd, 4096) >= 0)
2934                 ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
2935         else
2936                 ret = -1;
2937         strbuf_release(&sbuf);
2938         return ret;
2939 }
2940
2941 #define SMALL_FILE_SIZE (32*1024)
2942
2943 static int index_core(unsigned char *sha1, int fd, size_t size,
2944                       enum object_type type, const char *path,
2945                       unsigned flags)
2946 {
2947         int ret;
2948
2949         if (!size) {
2950                 ret = index_mem(sha1, NULL, size, type, path, flags);
2951         } else if (size <= SMALL_FILE_SIZE) {
2952                 char *buf = xmalloc(size);
2953                 if (size == read_in_full(fd, buf, size))
2954                         ret = index_mem(sha1, buf, size, type, path, flags);
2955                 else
2956                         ret = error("short read %s", strerror(errno));
2957                 free(buf);
2958         } else {
2959                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2960                 ret = index_mem(sha1, buf, size, type, path, flags);
2961                 munmap(buf, size);
2962         }
2963         return ret;
2964 }
2965
2966 /*
2967  * This creates one packfile per large blob unless bulk-checkin
2968  * machinery is "plugged".
2969  *
2970  * This also bypasses the usual "convert-to-git" dance, and that is on
2971  * purpose. We could write a streaming version of the converting
2972  * functions and insert that before feeding the data to fast-import
2973  * (or equivalent in-core API described above). However, that is
2974  * somewhat complicated, as we do not know the size of the filter
2975  * result, which we need to know beforehand when writing a git object.
2976  * Since the primary motivation for trying to stream from the working
2977  * tree file and to avoid mmaping it in core is to deal with large
2978  * binary blobs, they generally do not want to get any conversion, and
2979  * callers should avoid this code path when filters are requested.
2980  */
2981 static int index_stream(unsigned char *sha1, int fd, size_t size,
2982                         enum object_type type, const char *path,
2983                         unsigned flags)
2984 {
2985         return index_bulk_checkin(sha1, fd, size, type, path, flags);
2986 }
2987
2988 int index_fd(unsigned char *sha1, int fd, struct stat *st,
2989              enum object_type type, const char *path, unsigned flags)
2990 {
2991         int ret;
2992         size_t size = xsize_t(st->st_size);
2993
2994         if (!S_ISREG(st->st_mode))
2995                 ret = index_pipe(sha1, fd, type, path, flags);
2996         else if (size <= big_file_threshold || type != OBJ_BLOB ||
2997                  (path && would_convert_to_git(path, NULL, 0, 0)))
2998                 ret = index_core(sha1, fd, size, type, path, flags);
2999         else
3000                 ret = index_stream(sha1, fd, size, type, path, flags);
3001         close(fd);
3002         return ret;
3003 }
3004
3005 int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3006 {
3007         int fd;
3008         struct strbuf sb = STRBUF_INIT;
3009
3010         switch (st->st_mode & S_IFMT) {
3011         case S_IFREG:
3012                 fd = open(path, O_RDONLY);
3013                 if (fd < 0)
3014                         return error("open(\"%s\"): %s", path,
3015                                      strerror(errno));
3016                 if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3017                         return error("%s: failed to insert into database",
3018                                      path);
3019                 break;
3020         case S_IFLNK:
3021                 if (strbuf_readlink(&sb, path, st->st_size)) {
3022                         char *errstr = strerror(errno);
3023                         return error("readlink(\"%s\"): %s", path,
3024                                      errstr);
3025                 }
3026                 if (!(flags & HASH_WRITE_OBJECT))
3027                         hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3028                 else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3029                         return error("%s: failed to insert into database",
3030                                      path);
3031                 strbuf_release(&sb);
3032                 break;
3033         case S_IFDIR:
3034                 return resolve_gitlink_ref(path, "HEAD", sha1);
3035         default:
3036                 return error("%s: unsupported file type", path);
3037         }
3038         return 0;
3039 }
3040
3041 int read_pack_header(int fd, struct pack_header *header)
3042 {
3043         if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3044                 /* "eof before pack header was fully read" */
3045                 return PH_ERROR_EOF;
3046
3047         if (header->hdr_signature != htonl(PACK_SIGNATURE))
3048                 /* "protocol error (pack signature mismatch detected)" */
3049                 return PH_ERROR_PACK_SIGNATURE;
3050         if (!pack_version_ok(header->hdr_version))
3051                 /* "protocol error (pack version unsupported)" */
3052                 return PH_ERROR_PROTOCOL;
3053         return 0;
3054 }
3055
3056 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3057 {
3058         enum object_type type = sha1_object_info(sha1, NULL);
3059         if (type < 0)
3060                 die("%s is not a valid object", sha1_to_hex(sha1));
3061         if (type != expect)
3062                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3063                     typename(expect));
3064 }