Merge branch 'tr/add-i-no-escape'
[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 "delta.h"
11 #include "pack.h"
12 #include "blob.h"
13 #include "commit.h"
14 #include "tag.h"
15 #include "tree.h"
16 #include "tree-walk.h"
17 #include "refs.h"
18 #include "pack-revindex.h"
19 #include "sha1-lookup.h"
20
21 #ifndef O_NOATIME
22 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
23 #define O_NOATIME 01000000
24 #else
25 #define O_NOATIME 0
26 #endif
27 #endif
28
29 #define SZ_FMT PRIuMAX
30 static inline uintmax_t sz_fmt(size_t s) { return s; }
31
32 const unsigned char null_sha1[20];
33
34 /*
35  * This is meant to hold a *small* number of objects that you would
36  * want read_sha1_file() to be able to return, but yet you do not want
37  * to write them into the object store (e.g. a browse-only
38  * application).
39  */
40 static struct cached_object {
41         unsigned char sha1[20];
42         enum object_type type;
43         void *buf;
44         unsigned long size;
45 } *cached_objects;
46 static int cached_object_nr, cached_object_alloc;
47
48 static struct cached_object empty_tree = {
49         EMPTY_TREE_SHA1_BIN_LITERAL,
50         OBJ_TREE,
51         "",
52         0
53 };
54
55 static struct cached_object *find_cached_object(const unsigned char *sha1)
56 {
57         int i;
58         struct cached_object *co = cached_objects;
59
60         for (i = 0; i < cached_object_nr; i++, co++) {
61                 if (!hashcmp(co->sha1, sha1))
62                         return co;
63         }
64         if (!hashcmp(sha1, empty_tree.sha1))
65                 return &empty_tree;
66         return NULL;
67 }
68
69 int mkdir_in_gitdir(const char *path)
70 {
71         if (mkdir(path, 0777)) {
72                 int saved_errno = errno;
73                 struct stat st;
74                 struct strbuf sb = STRBUF_INIT;
75
76                 if (errno != EEXIST)
77                         return -1;
78                 /*
79                  * Are we looking at a path in a symlinked worktree
80                  * whose original repository does not yet have it?
81                  * e.g. .git/rr-cache pointing at its original
82                  * repository in which the user hasn't performed any
83                  * conflict resolution yet?
84                  */
85                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
86                     strbuf_readlink(&sb, path, st.st_size) ||
87                     !is_absolute_path(sb.buf) ||
88                     mkdir(sb.buf, 0777)) {
89                         strbuf_release(&sb);
90                         errno = saved_errno;
91                         return -1;
92                 }
93                 strbuf_release(&sb);
94         }
95         return adjust_shared_perm(path);
96 }
97
98 int safe_create_leading_directories(char *path)
99 {
100         char *pos = path + offset_1st_component(path);
101         struct stat st;
102
103         while (pos) {
104                 pos = strchr(pos, '/');
105                 if (!pos)
106                         break;
107                 while (*++pos == '/')
108                         ;
109                 if (!*pos)
110                         break;
111                 *--pos = '\0';
112                 if (!stat(path, &st)) {
113                         /* path exists */
114                         if (!S_ISDIR(st.st_mode)) {
115                                 *pos = '/';
116                                 return -3;
117                         }
118                 }
119                 else if (mkdir(path, 0777)) {
120                         *pos = '/';
121                         return -1;
122                 }
123                 else if (adjust_shared_perm(path)) {
124                         *pos = '/';
125                         return -2;
126                 }
127                 *pos++ = '/';
128         }
129         return 0;
130 }
131
132 int safe_create_leading_directories_const(const char *path)
133 {
134         /* path points to cache entries, so xstrdup before messing with it */
135         char *buf = xstrdup(path);
136         int result = safe_create_leading_directories(buf);
137         free(buf);
138         return result;
139 }
140
141 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
142 {
143         int i;
144         for (i = 0; i < 20; i++) {
145                 static char hex[] = "0123456789abcdef";
146                 unsigned int val = sha1[i];
147                 char *pos = pathbuf + i*2 + (i > 0);
148                 *pos++ = hex[val >> 4];
149                 *pos = hex[val & 0xf];
150         }
151 }
152
153 /*
154  * NOTE! This returns a statically allocated buffer, so you have to be
155  * careful about using it. Do an "xstrdup()" if you need to save the
156  * filename.
157  *
158  * Also note that this returns the location for creating.  Reading
159  * SHA1 file can happen from any alternate directory listed in the
160  * DB_ENVIRONMENT environment variable if it is not found in
161  * the primary object database.
162  */
163 char *sha1_file_name(const unsigned char *sha1)
164 {
165         static char buf[PATH_MAX];
166         const char *objdir;
167         int len;
168
169         objdir = get_object_directory();
170         len = strlen(objdir);
171
172         /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
173         if (len + 43 > PATH_MAX)
174                 die("insanely long object directory %s", objdir);
175         memcpy(buf, objdir, len);
176         buf[len] = '/';
177         buf[len+3] = '/';
178         buf[len+42] = '\0';
179         fill_sha1_path(buf + len + 1, sha1);
180         return buf;
181 }
182
183 static char *sha1_get_pack_name(const unsigned char *sha1,
184                                 char **name, char **base, const char *which)
185 {
186         static const char hex[] = "0123456789abcdef";
187         char *buf;
188         int i;
189
190         if (!*base) {
191                 const char *sha1_file_directory = get_object_directory();
192                 int len = strlen(sha1_file_directory);
193                 *base = xmalloc(len + 60);
194                 sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
195                         sha1_file_directory, which);
196                 *name = *base + len + 11;
197         }
198
199         buf = *name;
200
201         for (i = 0; i < 20; i++) {
202                 unsigned int val = *sha1++;
203                 *buf++ = hex[val >> 4];
204                 *buf++ = hex[val & 0xf];
205         }
206
207         return *base;
208 }
209
210 char *sha1_pack_name(const unsigned char *sha1)
211 {
212         static char *name, *base;
213
214         return sha1_get_pack_name(sha1, &name, &base, "pack");
215 }
216
217 char *sha1_pack_index_name(const unsigned char *sha1)
218 {
219         static char *name, *base;
220
221         return sha1_get_pack_name(sha1, &name, &base, "idx");
222 }
223
224 struct alternate_object_database *alt_odb_list;
225 static struct alternate_object_database **alt_odb_tail;
226
227 static void read_info_alternates(const char * alternates, int depth);
228 static int git_open_noatime(const char *name);
229
230 /*
231  * Prepare alternate object database registry.
232  *
233  * The variable alt_odb_list points at the list of struct
234  * alternate_object_database.  The elements on this list come from
235  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
236  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
237  * whose contents is similar to that environment variable but can be
238  * LF separated.  Its base points at a statically allocated buffer that
239  * contains "/the/directory/corresponding/to/.git/objects/...", while
240  * its name points just after the slash at the end of ".git/objects/"
241  * in the example above, and has enough space to hold 40-byte hex
242  * SHA1, an extra slash for the first level indirection, and the
243  * terminating NUL.
244  */
245 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
246 {
247         const char *objdir = get_object_directory();
248         struct alternate_object_database *ent;
249         struct alternate_object_database *alt;
250         /* 43 = 40-byte + 2 '/' + terminating NUL */
251         int pfxlen = len;
252         int entlen = pfxlen + 43;
253         int base_len = -1;
254
255         if (!is_absolute_path(entry) && relative_base) {
256                 /* Relative alt-odb */
257                 if (base_len < 0)
258                         base_len = strlen(relative_base) + 1;
259                 entlen += base_len;
260                 pfxlen += base_len;
261         }
262         ent = xmalloc(sizeof(*ent) + entlen);
263
264         if (!is_absolute_path(entry) && relative_base) {
265                 memcpy(ent->base, relative_base, base_len - 1);
266                 ent->base[base_len - 1] = '/';
267                 memcpy(ent->base + base_len, entry, len);
268         }
269         else
270                 memcpy(ent->base, entry, pfxlen);
271
272         ent->name = ent->base + pfxlen + 1;
273         ent->base[pfxlen + 3] = '/';
274         ent->base[pfxlen] = ent->base[entlen-1] = 0;
275
276         /* Detect cases where alternate disappeared */
277         if (!is_directory(ent->base)) {
278                 error("object directory %s does not exist; "
279                       "check .git/objects/info/alternates.",
280                       ent->base);
281                 free(ent);
282                 return -1;
283         }
284
285         /* Prevent the common mistake of listing the same
286          * thing twice, or object directory itself.
287          */
288         for (alt = alt_odb_list; alt; alt = alt->next) {
289                 if (!memcmp(ent->base, alt->base, pfxlen)) {
290                         free(ent);
291                         return -1;
292                 }
293         }
294         if (!memcmp(ent->base, objdir, pfxlen)) {
295                 free(ent);
296                 return -1;
297         }
298
299         /* add the alternate entry */
300         *alt_odb_tail = ent;
301         alt_odb_tail = &(ent->next);
302         ent->next = NULL;
303
304         /* recursively add alternates */
305         read_info_alternates(ent->base, depth + 1);
306
307         ent->base[pfxlen] = '/';
308
309         return 0;
310 }
311
312 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
313                                  const char *relative_base, int depth)
314 {
315         const char *cp, *last;
316
317         if (depth > 5) {
318                 error("%s: ignoring alternate object stores, nesting too deep.",
319                                 relative_base);
320                 return;
321         }
322
323         last = alt;
324         while (last < ep) {
325                 cp = last;
326                 if (cp < ep && *cp == '#') {
327                         while (cp < ep && *cp != sep)
328                                 cp++;
329                         last = cp + 1;
330                         continue;
331                 }
332                 while (cp < ep && *cp != sep)
333                         cp++;
334                 if (last != cp) {
335                         if (!is_absolute_path(last) && depth) {
336                                 error("%s: ignoring relative alternate object store %s",
337                                                 relative_base, last);
338                         } else {
339                                 link_alt_odb_entry(last, cp - last,
340                                                 relative_base, depth);
341                         }
342                 }
343                 while (cp < ep && *cp == sep)
344                         cp++;
345                 last = cp;
346         }
347 }
348
349 static void read_info_alternates(const char * relative_base, int depth)
350 {
351         char *map;
352         size_t mapsz;
353         struct stat st;
354         const char alt_file_name[] = "info/alternates";
355         /* Given that relative_base is no longer than PATH_MAX,
356            ensure that "path" has enough space to append "/", the
357            file name, "info/alternates", and a trailing NUL.  */
358         char path[PATH_MAX + 1 + sizeof alt_file_name];
359         int fd;
360
361         sprintf(path, "%s/%s", relative_base, alt_file_name);
362         fd = git_open_noatime(path);
363         if (fd < 0)
364                 return;
365         if (fstat(fd, &st) || (st.st_size == 0)) {
366                 close(fd);
367                 return;
368         }
369         mapsz = xsize_t(st.st_size);
370         map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
371         close(fd);
372
373         link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
374
375         munmap(map, mapsz);
376 }
377
378 void add_to_alternates_file(const char *reference)
379 {
380         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
381         int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
382         char *alt = mkpath("%s/objects\n", reference);
383         write_or_die(fd, alt, strlen(alt));
384         if (commit_lock_file(lock))
385                 die("could not close alternates file");
386         if (alt_odb_tail)
387                 link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
388 }
389
390 void foreach_alt_odb(alt_odb_fn fn, void *cb)
391 {
392         struct alternate_object_database *ent;
393
394         prepare_alt_odb();
395         for (ent = alt_odb_list; ent; ent = ent->next)
396                 if (fn(ent, cb))
397                         return;
398 }
399
400 void prepare_alt_odb(void)
401 {
402         const char *alt;
403
404         if (alt_odb_tail)
405                 return;
406
407         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
408         if (!alt) alt = "";
409
410         alt_odb_tail = &alt_odb_list;
411         link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
412
413         read_info_alternates(get_object_directory(), 0);
414 }
415
416 static int has_loose_object_local(const unsigned char *sha1)
417 {
418         char *name = sha1_file_name(sha1);
419         return !access(name, F_OK);
420 }
421
422 int has_loose_object_nonlocal(const unsigned char *sha1)
423 {
424         struct alternate_object_database *alt;
425         prepare_alt_odb();
426         for (alt = alt_odb_list; alt; alt = alt->next) {
427                 fill_sha1_path(alt->name, sha1);
428                 if (!access(alt->base, F_OK))
429                         return 1;
430         }
431         return 0;
432 }
433
434 static int has_loose_object(const unsigned char *sha1)
435 {
436         return has_loose_object_local(sha1) ||
437                has_loose_object_nonlocal(sha1);
438 }
439
440 static unsigned int pack_used_ctr;
441 static unsigned int pack_mmap_calls;
442 static unsigned int peak_pack_open_windows;
443 static unsigned int pack_open_windows;
444 static unsigned int pack_open_fds;
445 static unsigned int pack_max_fds;
446 static size_t peak_pack_mapped;
447 static size_t pack_mapped;
448 struct packed_git *packed_git;
449
450 void pack_report(void)
451 {
452         fprintf(stderr,
453                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
454                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
455                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
456                 sz_fmt(getpagesize()),
457                 sz_fmt(packed_git_window_size),
458                 sz_fmt(packed_git_limit));
459         fprintf(stderr,
460                 "pack_report: pack_used_ctr            = %10u\n"
461                 "pack_report: pack_mmap_calls          = %10u\n"
462                 "pack_report: pack_open_windows        = %10u / %10u\n"
463                 "pack_report: pack_mapped              = "
464                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
465                 pack_used_ctr,
466                 pack_mmap_calls,
467                 pack_open_windows, peak_pack_open_windows,
468                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
469 }
470
471 static int check_packed_git_idx(const char *path,  struct packed_git *p)
472 {
473         void *idx_map;
474         struct pack_idx_header *hdr;
475         size_t idx_size;
476         uint32_t version, nr, i, *index;
477         int fd = git_open_noatime(path);
478         struct stat st;
479
480         if (fd < 0)
481                 return -1;
482         if (fstat(fd, &st)) {
483                 close(fd);
484                 return -1;
485         }
486         idx_size = xsize_t(st.st_size);
487         if (idx_size < 4 * 256 + 20 + 20) {
488                 close(fd);
489                 return error("index file %s is too small", path);
490         }
491         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
492         close(fd);
493
494         hdr = idx_map;
495         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
496                 version = ntohl(hdr->idx_version);
497                 if (version < 2 || version > 2) {
498                         munmap(idx_map, idx_size);
499                         return error("index file %s is version %"PRIu32
500                                      " and is not supported by this binary"
501                                      " (try upgrading GIT to a newer version)",
502                                      path, version);
503                 }
504         } else
505                 version = 1;
506
507         nr = 0;
508         index = idx_map;
509         if (version > 1)
510                 index += 2;  /* skip index header */
511         for (i = 0; i < 256; i++) {
512                 uint32_t n = ntohl(index[i]);
513                 if (n < nr) {
514                         munmap(idx_map, idx_size);
515                         return error("non-monotonic index %s", path);
516                 }
517                 nr = n;
518         }
519
520         if (version == 1) {
521                 /*
522                  * Total size:
523                  *  - 256 index entries 4 bytes each
524                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
525                  *  - 20-byte SHA1 of the packfile
526                  *  - 20-byte SHA1 file checksum
527                  */
528                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
529                         munmap(idx_map, idx_size);
530                         return error("wrong index v1 file size in %s", path);
531                 }
532         } else if (version == 2) {
533                 /*
534                  * Minimum size:
535                  *  - 8 bytes of header
536                  *  - 256 index entries 4 bytes each
537                  *  - 20-byte sha1 entry * nr
538                  *  - 4-byte crc entry * nr
539                  *  - 4-byte offset entry * nr
540                  *  - 20-byte SHA1 of the packfile
541                  *  - 20-byte SHA1 file checksum
542                  * And after the 4-byte offset table might be a
543                  * variable sized table containing 8-byte entries
544                  * for offsets larger than 2^31.
545                  */
546                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
547                 unsigned long max_size = min_size;
548                 if (nr)
549                         max_size += (nr - 1)*8;
550                 if (idx_size < min_size || idx_size > max_size) {
551                         munmap(idx_map, idx_size);
552                         return error("wrong index v2 file size in %s", path);
553                 }
554                 if (idx_size != min_size &&
555                     /*
556                      * make sure we can deal with large pack offsets.
557                      * 31-bit signed offset won't be enough, neither
558                      * 32-bit unsigned one will be.
559                      */
560                     (sizeof(off_t) <= 4)) {
561                         munmap(idx_map, idx_size);
562                         return error("pack too large for current definition of off_t in %s", path);
563                 }
564         }
565
566         p->index_version = version;
567         p->index_data = idx_map;
568         p->index_size = idx_size;
569         p->num_objects = nr;
570         return 0;
571 }
572
573 int open_pack_index(struct packed_git *p)
574 {
575         char *idx_name;
576         int ret;
577
578         if (p->index_data)
579                 return 0;
580
581         idx_name = xstrdup(p->pack_name);
582         strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
583         ret = check_packed_git_idx(idx_name, p);
584         free(idx_name);
585         return ret;
586 }
587
588 static void scan_windows(struct packed_git *p,
589         struct packed_git **lru_p,
590         struct pack_window **lru_w,
591         struct pack_window **lru_l)
592 {
593         struct pack_window *w, *w_l;
594
595         for (w_l = NULL, w = p->windows; w; w = w->next) {
596                 if (!w->inuse_cnt) {
597                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
598                                 *lru_p = p;
599                                 *lru_w = w;
600                                 *lru_l = w_l;
601                         }
602                 }
603                 w_l = w;
604         }
605 }
606
607 static int unuse_one_window(struct packed_git *current, int keep_fd)
608 {
609         struct packed_git *p, *lru_p = NULL;
610         struct pack_window *lru_w = NULL, *lru_l = NULL;
611
612         if (current)
613                 scan_windows(current, &lru_p, &lru_w, &lru_l);
614         for (p = packed_git; p; p = p->next)
615                 scan_windows(p, &lru_p, &lru_w, &lru_l);
616         if (lru_p) {
617                 munmap(lru_w->base, lru_w->len);
618                 pack_mapped -= lru_w->len;
619                 if (lru_l)
620                         lru_l->next = lru_w->next;
621                 else {
622                         lru_p->windows = lru_w->next;
623                         if (!lru_p->windows && lru_p->pack_fd != -1
624                                 && lru_p->pack_fd != keep_fd) {
625                                 close(lru_p->pack_fd);
626                                 pack_open_fds--;
627                                 lru_p->pack_fd = -1;
628                         }
629                 }
630                 free(lru_w);
631                 pack_open_windows--;
632                 return 1;
633         }
634         return 0;
635 }
636
637 void release_pack_memory(size_t need, int fd)
638 {
639         size_t cur = pack_mapped;
640         while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
641                 ; /* nothing */
642 }
643
644 void *xmmap(void *start, size_t length,
645         int prot, int flags, int fd, off_t offset)
646 {
647         void *ret = mmap(start, length, prot, flags, fd, offset);
648         if (ret == MAP_FAILED) {
649                 if (!length)
650                         return NULL;
651                 release_pack_memory(length, fd);
652                 ret = mmap(start, length, prot, flags, fd, offset);
653                 if (ret == MAP_FAILED)
654                         die_errno("Out of memory? mmap failed");
655         }
656         return ret;
657 }
658
659 void close_pack_windows(struct packed_git *p)
660 {
661         while (p->windows) {
662                 struct pack_window *w = p->windows;
663
664                 if (w->inuse_cnt)
665                         die("pack '%s' still has open windows to it",
666                             p->pack_name);
667                 munmap(w->base, w->len);
668                 pack_mapped -= w->len;
669                 pack_open_windows--;
670                 p->windows = w->next;
671                 free(w);
672         }
673 }
674
675 void unuse_pack(struct pack_window **w_cursor)
676 {
677         struct pack_window *w = *w_cursor;
678         if (w) {
679                 w->inuse_cnt--;
680                 *w_cursor = NULL;
681         }
682 }
683
684 void close_pack_index(struct packed_git *p)
685 {
686         if (p->index_data) {
687                 munmap((void *)p->index_data, p->index_size);
688                 p->index_data = NULL;
689         }
690 }
691
692 /*
693  * This is used by git-repack in case a newly created pack happens to
694  * contain the same set of objects as an existing one.  In that case
695  * the resulting file might be different even if its name would be the
696  * same.  It is best to close any reference to the old pack before it is
697  * replaced on disk.  Of course no index pointers nor windows for given pack
698  * must subsist at this point.  If ever objects from this pack are requested
699  * again, the new version of the pack will be reinitialized through
700  * reprepare_packed_git().
701  */
702 void free_pack_by_name(const char *pack_name)
703 {
704         struct packed_git *p, **pp = &packed_git;
705
706         while (*pp) {
707                 p = *pp;
708                 if (strcmp(pack_name, p->pack_name) == 0) {
709                         clear_delta_base_cache();
710                         close_pack_windows(p);
711                         if (p->pack_fd != -1) {
712                                 close(p->pack_fd);
713                                 pack_open_fds--;
714                         }
715                         close_pack_index(p);
716                         free(p->bad_object_sha1);
717                         *pp = p->next;
718                         free(p);
719                         return;
720                 }
721                 pp = &p->next;
722         }
723 }
724
725 /*
726  * Do not call this directly as this leaks p->pack_fd on error return;
727  * call open_packed_git() instead.
728  */
729 static int open_packed_git_1(struct packed_git *p)
730 {
731         struct stat st;
732         struct pack_header hdr;
733         unsigned char sha1[20];
734         unsigned char *idx_sha1;
735         long fd_flag;
736
737         if (!p->index_data && open_pack_index(p))
738                 return error("packfile %s index unavailable", p->pack_name);
739
740         if (!pack_max_fds) {
741                 struct rlimit lim;
742                 unsigned int max_fds;
743
744                 if (getrlimit(RLIMIT_NOFILE, &lim))
745                         die_errno("cannot get RLIMIT_NOFILE");
746
747                 max_fds = lim.rlim_cur;
748
749                 /* Save 3 for stdin/stdout/stderr, 22 for work */
750                 if (25 < max_fds)
751                         pack_max_fds = max_fds - 25;
752                 else
753                         pack_max_fds = 1;
754         }
755
756         while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
757                 ; /* nothing */
758
759         p->pack_fd = git_open_noatime(p->pack_name);
760         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
761                 return -1;
762         pack_open_fds++;
763
764         /* If we created the struct before we had the pack we lack size. */
765         if (!p->pack_size) {
766                 if (!S_ISREG(st.st_mode))
767                         return error("packfile %s not a regular file", p->pack_name);
768                 p->pack_size = st.st_size;
769         } else if (p->pack_size != st.st_size)
770                 return error("packfile %s size changed", p->pack_name);
771
772         /* We leave these file descriptors open with sliding mmap;
773          * there is no point keeping them open across exec(), though.
774          */
775         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
776         if (fd_flag < 0)
777                 return error("cannot determine file descriptor flags");
778         fd_flag |= FD_CLOEXEC;
779         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
780                 return error("cannot set FD_CLOEXEC");
781
782         /* Verify we recognize this pack file format. */
783         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
784                 return error("file %s is far too short to be a packfile", p->pack_name);
785         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
786                 return error("file %s is not a GIT packfile", p->pack_name);
787         if (!pack_version_ok(hdr.hdr_version))
788                 return error("packfile %s is version %"PRIu32" and not"
789                         " supported (try upgrading GIT to a newer version)",
790                         p->pack_name, ntohl(hdr.hdr_version));
791
792         /* Verify the pack matches its index. */
793         if (p->num_objects != ntohl(hdr.hdr_entries))
794                 return error("packfile %s claims to have %"PRIu32" objects"
795                              " while index indicates %"PRIu32" objects",
796                              p->pack_name, ntohl(hdr.hdr_entries),
797                              p->num_objects);
798         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
799                 return error("end of packfile %s is unavailable", p->pack_name);
800         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
801                 return error("packfile %s signature is unavailable", p->pack_name);
802         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
803         if (hashcmp(sha1, idx_sha1))
804                 return error("packfile %s does not match index", p->pack_name);
805         return 0;
806 }
807
808 static int open_packed_git(struct packed_git *p)
809 {
810         if (!open_packed_git_1(p))
811                 return 0;
812         if (p->pack_fd != -1) {
813                 close(p->pack_fd);
814                 pack_open_fds--;
815                 p->pack_fd = -1;
816         }
817         return -1;
818 }
819
820 static int in_window(struct pack_window *win, off_t offset)
821 {
822         /* We must promise at least 20 bytes (one hash) after the
823          * offset is available from this window, otherwise the offset
824          * is not actually in this window and a different window (which
825          * has that one hash excess) must be used.  This is to support
826          * the object header and delta base parsing routines below.
827          */
828         off_t win_off = win->offset;
829         return win_off <= offset
830                 && (offset + 20) <= (win_off + win->len);
831 }
832
833 unsigned char *use_pack(struct packed_git *p,
834                 struct pack_window **w_cursor,
835                 off_t offset,
836                 unsigned int *left)
837 {
838         struct pack_window *win = *w_cursor;
839
840         /* Since packfiles end in a hash of their content and it's
841          * pointless to ask for an offset into the middle of that
842          * hash, and the in_window function above wouldn't match
843          * don't allow an offset too close to the end of the file.
844          */
845         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
846                 die("packfile %s cannot be accessed", p->pack_name);
847         if (offset > (p->pack_size - 20))
848                 die("offset beyond end of packfile (truncated pack?)");
849
850         if (!win || !in_window(win, offset)) {
851                 if (win)
852                         win->inuse_cnt--;
853                 for (win = p->windows; win; win = win->next) {
854                         if (in_window(win, offset))
855                                 break;
856                 }
857                 if (!win) {
858                         size_t window_align = packed_git_window_size / 2;
859                         off_t len;
860
861                         if (p->pack_fd == -1 && open_packed_git(p))
862                                 die("packfile %s cannot be accessed", p->pack_name);
863
864                         win = xcalloc(1, sizeof(*win));
865                         win->offset = (offset / window_align) * window_align;
866                         len = p->pack_size - win->offset;
867                         if (len > packed_git_window_size)
868                                 len = packed_git_window_size;
869                         win->len = (size_t)len;
870                         pack_mapped += win->len;
871                         while (packed_git_limit < pack_mapped
872                                 && unuse_one_window(p, p->pack_fd))
873                                 ; /* nothing */
874                         win->base = xmmap(NULL, win->len,
875                                 PROT_READ, MAP_PRIVATE,
876                                 p->pack_fd, win->offset);
877                         if (win->base == MAP_FAILED)
878                                 die("packfile %s cannot be mapped: %s",
879                                         p->pack_name,
880                                         strerror(errno));
881                         if (!win->offset && win->len == p->pack_size
882                                 && !p->do_not_close) {
883                                 close(p->pack_fd);
884                                 pack_open_fds--;
885                                 p->pack_fd = -1;
886                         }
887                         pack_mmap_calls++;
888                         pack_open_windows++;
889                         if (pack_mapped > peak_pack_mapped)
890                                 peak_pack_mapped = pack_mapped;
891                         if (pack_open_windows > peak_pack_open_windows)
892                                 peak_pack_open_windows = pack_open_windows;
893                         win->next = p->windows;
894                         p->windows = win;
895                 }
896         }
897         if (win != *w_cursor) {
898                 win->last_used = pack_used_ctr++;
899                 win->inuse_cnt++;
900                 *w_cursor = win;
901         }
902         offset -= win->offset;
903         if (left)
904                 *left = win->len - xsize_t(offset);
905         return win->base + offset;
906 }
907
908 static struct packed_git *alloc_packed_git(int extra)
909 {
910         struct packed_git *p = xmalloc(sizeof(*p) + extra);
911         memset(p, 0, sizeof(*p));
912         p->pack_fd = -1;
913         return p;
914 }
915
916 static void try_to_free_pack_memory(size_t size)
917 {
918         release_pack_memory(size, -1);
919 }
920
921 struct packed_git *add_packed_git(const char *path, int path_len, int local)
922 {
923         static int have_set_try_to_free_routine;
924         struct stat st;
925         struct packed_git *p = alloc_packed_git(path_len + 2);
926
927         if (!have_set_try_to_free_routine) {
928                 have_set_try_to_free_routine = 1;
929                 set_try_to_free_routine(try_to_free_pack_memory);
930         }
931
932         /*
933          * Make sure a corresponding .pack file exists and that
934          * the index looks sane.
935          */
936         path_len -= strlen(".idx");
937         if (path_len < 1) {
938                 free(p);
939                 return NULL;
940         }
941         memcpy(p->pack_name, path, path_len);
942
943         strcpy(p->pack_name + path_len, ".keep");
944         if (!access(p->pack_name, F_OK))
945                 p->pack_keep = 1;
946
947         strcpy(p->pack_name + path_len, ".pack");
948         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
949                 free(p);
950                 return NULL;
951         }
952
953         /* ok, it looks sane as far as we can check without
954          * actually mapping the pack file.
955          */
956         p->pack_size = st.st_size;
957         p->pack_local = local;
958         p->mtime = st.st_mtime;
959         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
960                 hashclr(p->sha1);
961         return p;
962 }
963
964 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
965 {
966         const char *path = sha1_pack_name(sha1);
967         struct packed_git *p = alloc_packed_git(strlen(path) + 1);
968
969         strcpy(p->pack_name, path);
970         hashcpy(p->sha1, sha1);
971         if (check_packed_git_idx(idx_path, p)) {
972                 free(p);
973                 return NULL;
974         }
975
976         return p;
977 }
978
979 void install_packed_git(struct packed_git *pack)
980 {
981         if (pack->pack_fd != -1)
982                 pack_open_fds++;
983
984         pack->next = packed_git;
985         packed_git = pack;
986 }
987
988 static void prepare_packed_git_one(char *objdir, int local)
989 {
990         /* Ensure that this buffer is large enough so that we can
991            append "/pack/" without clobbering the stack even if
992            strlen(objdir) were PATH_MAX.  */
993         char path[PATH_MAX + 1 + 4 + 1 + 1];
994         int len;
995         DIR *dir;
996         struct dirent *de;
997
998         sprintf(path, "%s/pack", objdir);
999         len = strlen(path);
1000         dir = opendir(path);
1001         if (!dir) {
1002                 if (errno != ENOENT)
1003                         error("unable to open object pack directory: %s: %s",
1004                               path, strerror(errno));
1005                 return;
1006         }
1007         path[len++] = '/';
1008         while ((de = readdir(dir)) != NULL) {
1009                 int namelen = strlen(de->d_name);
1010                 struct packed_git *p;
1011
1012                 if (!has_extension(de->d_name, ".idx"))
1013                         continue;
1014
1015                 if (len + namelen + 1 > sizeof(path))
1016                         continue;
1017
1018                 /* Don't reopen a pack we already have. */
1019                 strcpy(path + len, de->d_name);
1020                 for (p = packed_git; p; p = p->next) {
1021                         if (!memcmp(path, p->pack_name, len + namelen - 4))
1022                                 break;
1023                 }
1024                 if (p)
1025                         continue;
1026                 /* See if it really is a valid .idx file with corresponding
1027                  * .pack file that we can map.
1028                  */
1029                 p = add_packed_git(path, len + namelen, local);
1030                 if (!p)
1031                         continue;
1032                 install_packed_git(p);
1033         }
1034         closedir(dir);
1035 }
1036
1037 static int sort_pack(const void *a_, const void *b_)
1038 {
1039         struct packed_git *a = *((struct packed_git **)a_);
1040         struct packed_git *b = *((struct packed_git **)b_);
1041         int st;
1042
1043         /*
1044          * Local packs tend to contain objects specific to our
1045          * variant of the project than remote ones.  In addition,
1046          * remote ones could be on a network mounted filesystem.
1047          * Favor local ones for these reasons.
1048          */
1049         st = a->pack_local - b->pack_local;
1050         if (st)
1051                 return -st;
1052
1053         /*
1054          * Younger packs tend to contain more recent objects,
1055          * and more recent objects tend to get accessed more
1056          * often.
1057          */
1058         if (a->mtime < b->mtime)
1059                 return 1;
1060         else if (a->mtime == b->mtime)
1061                 return 0;
1062         return -1;
1063 }
1064
1065 static void rearrange_packed_git(void)
1066 {
1067         struct packed_git **ary, *p;
1068         int i, n;
1069
1070         for (n = 0, p = packed_git; p; p = p->next)
1071                 n++;
1072         if (n < 2)
1073                 return;
1074
1075         /* prepare an array of packed_git for easier sorting */
1076         ary = xcalloc(n, sizeof(struct packed_git *));
1077         for (n = 0, p = packed_git; p; p = p->next)
1078                 ary[n++] = p;
1079
1080         qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1081
1082         /* link them back again */
1083         for (i = 0; i < n - 1; i++)
1084                 ary[i]->next = ary[i + 1];
1085         ary[n - 1]->next = NULL;
1086         packed_git = ary[0];
1087
1088         free(ary);
1089 }
1090
1091 static int prepare_packed_git_run_once = 0;
1092 void prepare_packed_git(void)
1093 {
1094         struct alternate_object_database *alt;
1095
1096         if (prepare_packed_git_run_once)
1097                 return;
1098         prepare_packed_git_one(get_object_directory(), 1);
1099         prepare_alt_odb();
1100         for (alt = alt_odb_list; alt; alt = alt->next) {
1101                 alt->name[-1] = 0;
1102                 prepare_packed_git_one(alt->base, 0);
1103                 alt->name[-1] = '/';
1104         }
1105         rearrange_packed_git();
1106         prepare_packed_git_run_once = 1;
1107 }
1108
1109 void reprepare_packed_git(void)
1110 {
1111         discard_revindex();
1112         prepare_packed_git_run_once = 0;
1113         prepare_packed_git();
1114 }
1115
1116 static void mark_bad_packed_object(struct packed_git *p,
1117                                    const unsigned char *sha1)
1118 {
1119         unsigned i;
1120         for (i = 0; i < p->num_bad_objects; i++)
1121                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1122                         return;
1123         p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1124         hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1125         p->num_bad_objects++;
1126 }
1127
1128 static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1129 {
1130         struct packed_git *p;
1131         unsigned i;
1132
1133         for (p = packed_git; p; p = p->next)
1134                 for (i = 0; i < p->num_bad_objects; i++)
1135                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1136                                 return p;
1137         return NULL;
1138 }
1139
1140 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
1141 {
1142         unsigned char real_sha1[20];
1143         hash_sha1_file(map, size, type, real_sha1);
1144         return hashcmp(sha1, real_sha1) ? -1 : 0;
1145 }
1146
1147 static int git_open_noatime(const char *name)
1148 {
1149         static int sha1_file_open_flag = O_NOATIME;
1150
1151         for (;;) {
1152                 int fd = open(name, O_RDONLY | sha1_file_open_flag);
1153                 if (fd >= 0)
1154                         return fd;
1155
1156                 /* Might the failure be due to O_NOATIME? */
1157                 if (errno != ENOENT && sha1_file_open_flag) {
1158                         sha1_file_open_flag = 0;
1159                         continue;
1160                 }
1161
1162                 return -1;
1163         }
1164 }
1165
1166 static int open_sha1_file(const unsigned char *sha1)
1167 {
1168         int fd;
1169         char *name = sha1_file_name(sha1);
1170         struct alternate_object_database *alt;
1171
1172         fd = git_open_noatime(name);
1173         if (fd >= 0)
1174                 return fd;
1175
1176         prepare_alt_odb();
1177         errno = ENOENT;
1178         for (alt = alt_odb_list; alt; alt = alt->next) {
1179                 name = alt->name;
1180                 fill_sha1_path(name, sha1);
1181                 fd = git_open_noatime(alt->base);
1182                 if (fd >= 0)
1183                         return fd;
1184         }
1185         return -1;
1186 }
1187
1188 static void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1189 {
1190         void *map;
1191         int fd;
1192
1193         fd = open_sha1_file(sha1);
1194         map = NULL;
1195         if (fd >= 0) {
1196                 struct stat st;
1197
1198                 if (!fstat(fd, &st)) {
1199                         *size = xsize_t(st.st_size);
1200                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1201                 }
1202                 close(fd);
1203         }
1204         return map;
1205 }
1206
1207 static int legacy_loose_object(unsigned char *map)
1208 {
1209         unsigned int word;
1210
1211         /*
1212          * Is it a zlib-compressed buffer? If so, the first byte
1213          * must be 0x78 (15-bit window size, deflated), and the
1214          * first 16-bit word is evenly divisible by 31
1215          */
1216         word = (map[0] << 8) + map[1];
1217         if (map[0] == 0x78 && !(word % 31))
1218                 return 1;
1219         else
1220                 return 0;
1221 }
1222
1223 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1224                 unsigned long len, enum object_type *type, unsigned long *sizep)
1225 {
1226         unsigned shift;
1227         unsigned long size, c;
1228         unsigned long used = 0;
1229
1230         c = buf[used++];
1231         *type = (c >> 4) & 7;
1232         size = c & 15;
1233         shift = 4;
1234         while (c & 0x80) {
1235                 if (len <= used || bitsizeof(long) <= shift) {
1236                         error("bad object header");
1237                         return 0;
1238                 }
1239                 c = buf[used++];
1240                 size += (c & 0x7f) << shift;
1241                 shift += 7;
1242         }
1243         *sizep = size;
1244         return used;
1245 }
1246
1247 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1248 {
1249         unsigned long size, used;
1250         static const char valid_loose_object_type[8] = {
1251                 0, /* OBJ_EXT */
1252                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1253                 0, /* "delta" and others are invalid in a loose object */
1254         };
1255         enum object_type type;
1256
1257         /* Get the data stream */
1258         memset(stream, 0, sizeof(*stream));
1259         stream->next_in = map;
1260         stream->avail_in = mapsize;
1261         stream->next_out = buffer;
1262         stream->avail_out = bufsiz;
1263
1264         if (legacy_loose_object(map)) {
1265                 git_inflate_init(stream);
1266                 return git_inflate(stream, 0);
1267         }
1268
1269
1270         /*
1271          * There used to be a second loose object header format which
1272          * was meant to mimic the in-pack format, allowing for direct
1273          * copy of the object data.  This format turned up not to be
1274          * really worth it and we don't write it any longer.  But we
1275          * can still read it.
1276          */
1277         used = unpack_object_header_buffer(map, mapsize, &type, &size);
1278         if (!used || !valid_loose_object_type[type])
1279                 return -1;
1280         map += used;
1281         mapsize -= used;
1282
1283         /* Set up the stream for the rest.. */
1284         stream->next_in = map;
1285         stream->avail_in = mapsize;
1286         git_inflate_init(stream);
1287
1288         /* And generate the fake traditional header */
1289         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1290                                          typename(type), size);
1291         return 0;
1292 }
1293
1294 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1295 {
1296         int bytes = strlen(buffer) + 1;
1297         unsigned char *buf = xmallocz(size);
1298         unsigned long n;
1299         int status = Z_OK;
1300
1301         n = stream->total_out - bytes;
1302         if (n > size)
1303                 n = size;
1304         memcpy(buf, (char *) buffer + bytes, n);
1305         bytes = n;
1306         if (bytes <= size) {
1307                 /*
1308                  * The above condition must be (bytes <= size), not
1309                  * (bytes < size).  In other words, even though we
1310                  * expect no more output and set avail_out to zero,
1311                  * the input zlib stream may have bytes that express
1312                  * "this concludes the stream", and we *do* want to
1313                  * eat that input.
1314                  *
1315                  * Otherwise we would not be able to test that we
1316                  * consumed all the input to reach the expected size;
1317                  * we also want to check that zlib tells us that all
1318                  * went well with status == Z_STREAM_END at the end.
1319                  */
1320                 stream->next_out = buf + bytes;
1321                 stream->avail_out = size - bytes;
1322                 while (status == Z_OK)
1323                         status = git_inflate(stream, Z_FINISH);
1324         }
1325         if (status == Z_STREAM_END && !stream->avail_in) {
1326                 git_inflate_end(stream);
1327                 return buf;
1328         }
1329
1330         if (status < 0)
1331                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1332         else if (stream->avail_in)
1333                 error("garbage at end of loose object '%s'",
1334                       sha1_to_hex(sha1));
1335         free(buf);
1336         return NULL;
1337 }
1338
1339 /*
1340  * We used to just use "sscanf()", but that's actually way
1341  * too permissive for what we want to check. So do an anal
1342  * object header parse by hand.
1343  */
1344 static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1345 {
1346         char type[10];
1347         int i;
1348         unsigned long size;
1349
1350         /*
1351          * The type can be at most ten bytes (including the
1352          * terminating '\0' that we add), and is followed by
1353          * a space.
1354          */
1355         i = 0;
1356         for (;;) {
1357                 char c = *hdr++;
1358                 if (c == ' ')
1359                         break;
1360                 type[i++] = c;
1361                 if (i >= sizeof(type))
1362                         return -1;
1363         }
1364         type[i] = 0;
1365
1366         /*
1367          * The length must follow immediately, and be in canonical
1368          * decimal format (ie "010" is not valid).
1369          */
1370         size = *hdr++ - '0';
1371         if (size > 9)
1372                 return -1;
1373         if (size) {
1374                 for (;;) {
1375                         unsigned long c = *hdr - '0';
1376                         if (c > 9)
1377                                 break;
1378                         hdr++;
1379                         size = size * 10 + c;
1380                 }
1381         }
1382         *sizep = size;
1383
1384         /*
1385          * The length must be followed by a zero byte
1386          */
1387         return *hdr ? -1 : type_from_string(type);
1388 }
1389
1390 static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1391 {
1392         int ret;
1393         z_stream stream;
1394         char hdr[8192];
1395
1396         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1397         if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1398                 return NULL;
1399
1400         return unpack_sha1_rest(&stream, hdr, *size, sha1);
1401 }
1402
1403 unsigned long get_size_from_delta(struct packed_git *p,
1404                                   struct pack_window **w_curs,
1405                                   off_t curpos)
1406 {
1407         const unsigned char *data;
1408         unsigned char delta_head[20], *in;
1409         z_stream stream;
1410         int st;
1411
1412         memset(&stream, 0, sizeof(stream));
1413         stream.next_out = delta_head;
1414         stream.avail_out = sizeof(delta_head);
1415
1416         git_inflate_init(&stream);
1417         do {
1418                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1419                 stream.next_in = in;
1420                 st = git_inflate(&stream, Z_FINISH);
1421                 curpos += stream.next_in - in;
1422         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1423                  stream.total_out < sizeof(delta_head));
1424         git_inflate_end(&stream);
1425         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1426                 error("delta data unpack-initial failed");
1427                 return 0;
1428         }
1429
1430         /* Examine the initial part of the delta to figure out
1431          * the result size.
1432          */
1433         data = delta_head;
1434
1435         /* ignore base size */
1436         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1437
1438         /* Read the result size */
1439         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1440 }
1441
1442 static off_t get_delta_base(struct packed_git *p,
1443                                     struct pack_window **w_curs,
1444                                     off_t *curpos,
1445                                     enum object_type type,
1446                                     off_t delta_obj_offset)
1447 {
1448         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1449         off_t base_offset;
1450
1451         /* use_pack() assured us we have [base_info, base_info + 20)
1452          * as a range that we can look at without walking off the
1453          * end of the mapped window.  Its actually the hash size
1454          * that is assured.  An OFS_DELTA longer than the hash size
1455          * is stupid, as then a REF_DELTA would be smaller to store.
1456          */
1457         if (type == OBJ_OFS_DELTA) {
1458                 unsigned used = 0;
1459                 unsigned char c = base_info[used++];
1460                 base_offset = c & 127;
1461                 while (c & 128) {
1462                         base_offset += 1;
1463                         if (!base_offset || MSB(base_offset, 7))
1464                                 return 0;  /* overflow */
1465                         c = base_info[used++];
1466                         base_offset = (base_offset << 7) + (c & 127);
1467                 }
1468                 base_offset = delta_obj_offset - base_offset;
1469                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1470                         return 0;  /* out of bound */
1471                 *curpos += used;
1472         } else if (type == OBJ_REF_DELTA) {
1473                 /* The base entry _must_ be in the same pack */
1474                 base_offset = find_pack_entry_one(base_info, p);
1475                 *curpos += 20;
1476         } else
1477                 die("I am totally screwed");
1478         return base_offset;
1479 }
1480
1481 /* forward declaration for a mutually recursive function */
1482 static int packed_object_info(struct packed_git *p, off_t offset,
1483                               unsigned long *sizep);
1484
1485 static int packed_delta_info(struct packed_git *p,
1486                              struct pack_window **w_curs,
1487                              off_t curpos,
1488                              enum object_type type,
1489                              off_t obj_offset,
1490                              unsigned long *sizep)
1491 {
1492         off_t base_offset;
1493
1494         base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1495         if (!base_offset)
1496                 return OBJ_BAD;
1497         type = packed_object_info(p, base_offset, NULL);
1498         if (type <= OBJ_NONE) {
1499                 struct revindex_entry *revidx;
1500                 const unsigned char *base_sha1;
1501                 revidx = find_pack_revindex(p, base_offset);
1502                 if (!revidx)
1503                         return OBJ_BAD;
1504                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1505                 mark_bad_packed_object(p, base_sha1);
1506                 type = sha1_object_info(base_sha1, NULL);
1507                 if (type <= OBJ_NONE)
1508                         return OBJ_BAD;
1509         }
1510
1511         /* We choose to only get the type of the base object and
1512          * ignore potentially corrupt pack file that expects the delta
1513          * based on a base with a wrong size.  This saves tons of
1514          * inflate() calls.
1515          */
1516         if (sizep) {
1517                 *sizep = get_size_from_delta(p, w_curs, curpos);
1518                 if (*sizep == 0)
1519                         type = OBJ_BAD;
1520         }
1521
1522         return type;
1523 }
1524
1525 static int unpack_object_header(struct packed_git *p,
1526                                 struct pack_window **w_curs,
1527                                 off_t *curpos,
1528                                 unsigned long *sizep)
1529 {
1530         unsigned char *base;
1531         unsigned int left;
1532         unsigned long used;
1533         enum object_type type;
1534
1535         /* use_pack() assures us we have [base, base + 20) available
1536          * as a range that we can look at.  (Its actually the hash
1537          * size that is assured.)  With our object header encoding
1538          * the maximum deflated object size is 2^137, which is just
1539          * insane, so we know won't exceed what we have been given.
1540          */
1541         base = use_pack(p, w_curs, *curpos, &left);
1542         used = unpack_object_header_buffer(base, left, &type, sizep);
1543         if (!used) {
1544                 type = OBJ_BAD;
1545         } else
1546                 *curpos += used;
1547
1548         return type;
1549 }
1550
1551 const char *packed_object_info_detail(struct packed_git *p,
1552                                       off_t obj_offset,
1553                                       unsigned long *size,
1554                                       unsigned long *store_size,
1555                                       unsigned int *delta_chain_length,
1556                                       unsigned char *base_sha1)
1557 {
1558         struct pack_window *w_curs = NULL;
1559         off_t curpos;
1560         unsigned long dummy;
1561         unsigned char *next_sha1;
1562         enum object_type type;
1563         struct revindex_entry *revidx;
1564
1565         *delta_chain_length = 0;
1566         curpos = obj_offset;
1567         type = unpack_object_header(p, &w_curs, &curpos, size);
1568
1569         revidx = find_pack_revindex(p, obj_offset);
1570         *store_size = revidx[1].offset - obj_offset;
1571
1572         for (;;) {
1573                 switch (type) {
1574                 default:
1575                         die("pack %s contains unknown object type %d",
1576                             p->pack_name, type);
1577                 case OBJ_COMMIT:
1578                 case OBJ_TREE:
1579                 case OBJ_BLOB:
1580                 case OBJ_TAG:
1581                         unuse_pack(&w_curs);
1582                         return typename(type);
1583                 case OBJ_OFS_DELTA:
1584                         obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1585                         if (!obj_offset)
1586                                 die("pack %s contains bad delta base reference of type %s",
1587                                     p->pack_name, typename(type));
1588                         if (*delta_chain_length == 0) {
1589                                 revidx = find_pack_revindex(p, obj_offset);
1590                                 hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
1591                         }
1592                         break;
1593                 case OBJ_REF_DELTA:
1594                         next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1595                         if (*delta_chain_length == 0)
1596                                 hashcpy(base_sha1, next_sha1);
1597                         obj_offset = find_pack_entry_one(next_sha1, p);
1598                         break;
1599                 }
1600                 (*delta_chain_length)++;
1601                 curpos = obj_offset;
1602                 type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1603         }
1604 }
1605
1606 static int packed_object_info(struct packed_git *p, off_t obj_offset,
1607                               unsigned long *sizep)
1608 {
1609         struct pack_window *w_curs = NULL;
1610         unsigned long size;
1611         off_t curpos = obj_offset;
1612         enum object_type type;
1613
1614         type = unpack_object_header(p, &w_curs, &curpos, &size);
1615
1616         switch (type) {
1617         case OBJ_OFS_DELTA:
1618         case OBJ_REF_DELTA:
1619                 type = packed_delta_info(p, &w_curs, curpos,
1620                                          type, obj_offset, sizep);
1621                 break;
1622         case OBJ_COMMIT:
1623         case OBJ_TREE:
1624         case OBJ_BLOB:
1625         case OBJ_TAG:
1626                 if (sizep)
1627                         *sizep = size;
1628                 break;
1629         default:
1630                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1631                       type, (uintmax_t)obj_offset, p->pack_name);
1632                 type = OBJ_BAD;
1633         }
1634         unuse_pack(&w_curs);
1635         return type;
1636 }
1637
1638 static void *unpack_compressed_entry(struct packed_git *p,
1639                                     struct pack_window **w_curs,
1640                                     off_t curpos,
1641                                     unsigned long size)
1642 {
1643         int st;
1644         z_stream stream;
1645         unsigned char *buffer, *in;
1646
1647         buffer = xmallocz(size);
1648         memset(&stream, 0, sizeof(stream));
1649         stream.next_out = buffer;
1650         stream.avail_out = size + 1;
1651
1652         git_inflate_init(&stream);
1653         do {
1654                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1655                 stream.next_in = in;
1656                 st = git_inflate(&stream, Z_FINISH);
1657                 if (!stream.avail_out)
1658                         break; /* the payload is larger than it should be */
1659                 curpos += stream.next_in - in;
1660         } while (st == Z_OK || st == Z_BUF_ERROR);
1661         git_inflate_end(&stream);
1662         if ((st != Z_STREAM_END) || stream.total_out != size) {
1663                 free(buffer);
1664                 return NULL;
1665         }
1666
1667         return buffer;
1668 }
1669
1670 #define MAX_DELTA_CACHE (256)
1671
1672 static size_t delta_base_cached;
1673
1674 static struct delta_base_cache_lru_list {
1675         struct delta_base_cache_lru_list *prev;
1676         struct delta_base_cache_lru_list *next;
1677 } delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1678
1679 static struct delta_base_cache_entry {
1680         struct delta_base_cache_lru_list lru;
1681         void *data;
1682         struct packed_git *p;
1683         off_t base_offset;
1684         unsigned long size;
1685         enum object_type type;
1686 } delta_base_cache[MAX_DELTA_CACHE];
1687
1688 static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1689 {
1690         unsigned long hash;
1691
1692         hash = (unsigned long)p + (unsigned long)base_offset;
1693         hash += (hash >> 8) + (hash >> 16);
1694         return hash % MAX_DELTA_CACHE;
1695 }
1696
1697 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1698         unsigned long *base_size, enum object_type *type, int keep_cache)
1699 {
1700         void *ret;
1701         unsigned long hash = pack_entry_hash(p, base_offset);
1702         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1703
1704         ret = ent->data;
1705         if (!ret || ent->p != p || ent->base_offset != base_offset)
1706                 return unpack_entry(p, base_offset, type, base_size);
1707
1708         if (!keep_cache) {
1709                 ent->data = NULL;
1710                 ent->lru.next->prev = ent->lru.prev;
1711                 ent->lru.prev->next = ent->lru.next;
1712                 delta_base_cached -= ent->size;
1713         } else {
1714                 ret = xmemdupz(ent->data, ent->size);
1715         }
1716         *type = ent->type;
1717         *base_size = ent->size;
1718         return ret;
1719 }
1720
1721 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1722 {
1723         if (ent->data) {
1724                 free(ent->data);
1725                 ent->data = NULL;
1726                 ent->lru.next->prev = ent->lru.prev;
1727                 ent->lru.prev->next = ent->lru.next;
1728                 delta_base_cached -= ent->size;
1729         }
1730 }
1731
1732 void clear_delta_base_cache(void)
1733 {
1734         unsigned long p;
1735         for (p = 0; p < MAX_DELTA_CACHE; p++)
1736                 release_delta_base_cache(&delta_base_cache[p]);
1737 }
1738
1739 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1740         void *base, unsigned long base_size, enum object_type type)
1741 {
1742         unsigned long hash = pack_entry_hash(p, base_offset);
1743         struct delta_base_cache_entry *ent = delta_base_cache + hash;
1744         struct delta_base_cache_lru_list *lru;
1745
1746         release_delta_base_cache(ent);
1747         delta_base_cached += base_size;
1748
1749         for (lru = delta_base_cache_lru.next;
1750              delta_base_cached > delta_base_cache_limit
1751              && lru != &delta_base_cache_lru;
1752              lru = lru->next) {
1753                 struct delta_base_cache_entry *f = (void *)lru;
1754                 if (f->type == OBJ_BLOB)
1755                         release_delta_base_cache(f);
1756         }
1757         for (lru = delta_base_cache_lru.next;
1758              delta_base_cached > delta_base_cache_limit
1759              && lru != &delta_base_cache_lru;
1760              lru = lru->next) {
1761                 struct delta_base_cache_entry *f = (void *)lru;
1762                 release_delta_base_cache(f);
1763         }
1764
1765         ent->p = p;
1766         ent->base_offset = base_offset;
1767         ent->type = type;
1768         ent->data = base;
1769         ent->size = base_size;
1770         ent->lru.next = &delta_base_cache_lru;
1771         ent->lru.prev = delta_base_cache_lru.prev;
1772         delta_base_cache_lru.prev->next = &ent->lru;
1773         delta_base_cache_lru.prev = &ent->lru;
1774 }
1775
1776 static void *read_object(const unsigned char *sha1, enum object_type *type,
1777                          unsigned long *size);
1778
1779 static void *unpack_delta_entry(struct packed_git *p,
1780                                 struct pack_window **w_curs,
1781                                 off_t curpos,
1782                                 unsigned long delta_size,
1783                                 off_t obj_offset,
1784                                 enum object_type *type,
1785                                 unsigned long *sizep)
1786 {
1787         void *delta_data, *result, *base;
1788         unsigned long base_size;
1789         off_t base_offset;
1790
1791         base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1792         if (!base_offset) {
1793                 error("failed to validate delta base reference "
1794                       "at offset %"PRIuMAX" from %s",
1795                       (uintmax_t)curpos, p->pack_name);
1796                 return NULL;
1797         }
1798         unuse_pack(w_curs);
1799         base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
1800         if (!base) {
1801                 /*
1802                  * We're probably in deep shit, but let's try to fetch
1803                  * the required base anyway from another pack or loose.
1804                  * This is costly but should happen only in the presence
1805                  * of a corrupted pack, and is better than failing outright.
1806                  */
1807                 struct revindex_entry *revidx;
1808                 const unsigned char *base_sha1;
1809                 revidx = find_pack_revindex(p, base_offset);
1810                 if (!revidx)
1811                         return NULL;
1812                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1813                 error("failed to read delta base object %s"
1814                       " at offset %"PRIuMAX" from %s",
1815                       sha1_to_hex(base_sha1), (uintmax_t)base_offset,
1816                       p->pack_name);
1817                 mark_bad_packed_object(p, base_sha1);
1818                 base = read_object(base_sha1, type, &base_size);
1819                 if (!base)
1820                         return NULL;
1821         }
1822
1823         delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1824         if (!delta_data) {
1825                 error("failed to unpack compressed delta "
1826                       "at offset %"PRIuMAX" from %s",
1827                       (uintmax_t)curpos, p->pack_name);
1828                 free(base);
1829                 return NULL;
1830         }
1831         result = patch_delta(base, base_size,
1832                              delta_data, delta_size,
1833                              sizep);
1834         if (!result)
1835                 die("failed to apply delta");
1836         free(delta_data);
1837         add_delta_base_cache(p, base_offset, base, base_size, *type);
1838         return result;
1839 }
1840
1841 int do_check_packed_object_crc;
1842
1843 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1844                    enum object_type *type, unsigned long *sizep)
1845 {
1846         struct pack_window *w_curs = NULL;
1847         off_t curpos = obj_offset;
1848         void *data;
1849
1850         if (do_check_packed_object_crc && p->index_version > 1) {
1851                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1852                 unsigned long len = revidx[1].offset - obj_offset;
1853                 if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1854                         const unsigned char *sha1 =
1855                                 nth_packed_object_sha1(p, revidx->nr);
1856                         error("bad packed object CRC for %s",
1857                               sha1_to_hex(sha1));
1858                         mark_bad_packed_object(p, sha1);
1859                         unuse_pack(&w_curs);
1860                         return NULL;
1861                 }
1862         }
1863
1864         *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1865         switch (*type) {
1866         case OBJ_OFS_DELTA:
1867         case OBJ_REF_DELTA:
1868                 data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1869                                           obj_offset, type, sizep);
1870                 break;
1871         case OBJ_COMMIT:
1872         case OBJ_TREE:
1873         case OBJ_BLOB:
1874         case OBJ_TAG:
1875                 data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1876                 break;
1877         default:
1878                 data = NULL;
1879                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1880                       *type, (uintmax_t)obj_offset, p->pack_name);
1881         }
1882         unuse_pack(&w_curs);
1883         return data;
1884 }
1885
1886 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1887                                             uint32_t n)
1888 {
1889         const unsigned char *index = p->index_data;
1890         if (!index) {
1891                 if (open_pack_index(p))
1892                         return NULL;
1893                 index = p->index_data;
1894         }
1895         if (n >= p->num_objects)
1896                 return NULL;
1897         index += 4 * 256;
1898         if (p->index_version == 1) {
1899                 return index + 24 * n + 4;
1900         } else {
1901                 index += 8;
1902                 return index + 20 * n;
1903         }
1904 }
1905
1906 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1907 {
1908         const unsigned char *index = p->index_data;
1909         index += 4 * 256;
1910         if (p->index_version == 1) {
1911                 return ntohl(*((uint32_t *)(index + 24 * n)));
1912         } else {
1913                 uint32_t off;
1914                 index += 8 + p->num_objects * (20 + 4);
1915                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1916                 if (!(off & 0x80000000))
1917                         return off;
1918                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1919                 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1920                                    ntohl(*((uint32_t *)(index + 4)));
1921         }
1922 }
1923
1924 off_t find_pack_entry_one(const unsigned char *sha1,
1925                                   struct packed_git *p)
1926 {
1927         const uint32_t *level1_ofs = p->index_data;
1928         const unsigned char *index = p->index_data;
1929         unsigned hi, lo, stride;
1930         static int use_lookup = -1;
1931         static int debug_lookup = -1;
1932
1933         if (debug_lookup < 0)
1934                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1935
1936         if (!index) {
1937                 if (open_pack_index(p))
1938                         return 0;
1939                 level1_ofs = p->index_data;
1940                 index = p->index_data;
1941         }
1942         if (p->index_version > 1) {
1943                 level1_ofs += 2;
1944                 index += 8;
1945         }
1946         index += 4 * 256;
1947         hi = ntohl(level1_ofs[*sha1]);
1948         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1949         if (p->index_version > 1) {
1950                 stride = 20;
1951         } else {
1952                 stride = 24;
1953                 index += 4;
1954         }
1955
1956         if (debug_lookup)
1957                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1958                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1959
1960         if (use_lookup < 0)
1961                 use_lookup = !!getenv("GIT_USE_LOOKUP");
1962         if (use_lookup) {
1963                 int pos = sha1_entry_pos(index, stride, 0,
1964                                          lo, hi, p->num_objects, sha1);
1965                 if (pos < 0)
1966                         return 0;
1967                 return nth_packed_object_offset(p, pos);
1968         }
1969
1970         do {
1971                 unsigned mi = (lo + hi) / 2;
1972                 int cmp = hashcmp(index + mi * stride, sha1);
1973
1974                 if (debug_lookup)
1975                         printf("lo %u hi %u rg %u mi %u\n",
1976                                lo, hi, hi - lo, mi);
1977                 if (!cmp)
1978                         return nth_packed_object_offset(p, mi);
1979                 if (cmp > 0)
1980                         hi = mi;
1981                 else
1982                         lo = mi+1;
1983         } while (lo < hi);
1984         return 0;
1985 }
1986
1987 static int is_pack_valid(struct packed_git *p)
1988 {
1989         /* An already open pack is known to be valid. */
1990         if (p->pack_fd != -1)
1991                 return 1;
1992
1993         /* If the pack has one window completely covering the
1994          * file size, the pack is known to be valid even if
1995          * the descriptor is not currently open.
1996          */
1997         if (p->windows) {
1998                 struct pack_window *w = p->windows;
1999
2000                 if (!w->offset && w->len == p->pack_size)
2001                         return 1;
2002         }
2003
2004         /* Force the pack to open to prove its valid. */
2005         return !open_packed_git(p);
2006 }
2007
2008 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2009 {
2010         static struct packed_git *last_found = (void *)1;
2011         struct packed_git *p;
2012         off_t offset;
2013
2014         prepare_packed_git();
2015         if (!packed_git)
2016                 return 0;
2017         p = (last_found == (void *)1) ? packed_git : last_found;
2018
2019         do {
2020                 if (p->num_bad_objects) {
2021                         unsigned i;
2022                         for (i = 0; i < p->num_bad_objects; i++)
2023                                 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2024                                         goto next;
2025                 }
2026
2027                 offset = find_pack_entry_one(sha1, p);
2028                 if (offset) {
2029                         /*
2030                          * We are about to tell the caller where they can
2031                          * locate the requested object.  We better make
2032                          * sure the packfile is still here and can be
2033                          * accessed before supplying that answer, as
2034                          * it may have been deleted since the index
2035                          * was loaded!
2036                          */
2037                         if (!is_pack_valid(p)) {
2038                                 error("packfile %s cannot be accessed", p->pack_name);
2039                                 goto next;
2040                         }
2041                         e->offset = offset;
2042                         e->p = p;
2043                         hashcpy(e->sha1, sha1);
2044                         last_found = p;
2045                         return 1;
2046                 }
2047
2048                 next:
2049                 if (p == last_found)
2050                         p = packed_git;
2051                 else
2052                         p = p->next;
2053                 if (p == last_found)
2054                         p = p->next;
2055         } while (p);
2056         return 0;
2057 }
2058
2059 struct packed_git *find_sha1_pack(const unsigned char *sha1,
2060                                   struct packed_git *packs)
2061 {
2062         struct packed_git *p;
2063
2064         for (p = packs; p; p = p->next) {
2065                 if (find_pack_entry_one(sha1, p))
2066                         return p;
2067         }
2068         return NULL;
2069
2070 }
2071
2072 static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
2073 {
2074         int status;
2075         unsigned long mapsize, size;
2076         void *map;
2077         z_stream stream;
2078         char hdr[32];
2079
2080         map = map_sha1_file(sha1, &mapsize);
2081         if (!map)
2082                 return error("unable to find %s", sha1_to_hex(sha1));
2083         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2084                 status = error("unable to unpack %s header",
2085                                sha1_to_hex(sha1));
2086         else if ((status = parse_sha1_header(hdr, &size)) < 0)
2087                 status = error("unable to parse %s header", sha1_to_hex(sha1));
2088         else if (sizep)
2089                 *sizep = size;
2090         git_inflate_end(&stream);
2091         munmap(map, mapsize);
2092         return status;
2093 }
2094
2095 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2096 {
2097         struct cached_object *co;
2098         struct pack_entry e;
2099         int status;
2100
2101         co = find_cached_object(sha1);
2102         if (co) {
2103                 if (sizep)
2104                         *sizep = co->size;
2105                 return co->type;
2106         }
2107
2108         if (!find_pack_entry(sha1, &e)) {
2109                 /* Most likely it's a loose object. */
2110                 status = sha1_loose_object_info(sha1, sizep);
2111                 if (status >= 0)
2112                         return status;
2113
2114                 /* Not a loose object; someone else may have just packed it. */
2115                 reprepare_packed_git();
2116                 if (!find_pack_entry(sha1, &e))
2117                         return status;
2118         }
2119
2120         status = packed_object_info(e.p, e.offset, sizep);
2121         if (status < 0) {
2122                 mark_bad_packed_object(e.p, sha1);
2123                 status = sha1_object_info(sha1, sizep);
2124         }
2125
2126         return status;
2127 }
2128
2129 static void *read_packed_sha1(const unsigned char *sha1,
2130                               enum object_type *type, unsigned long *size)
2131 {
2132         struct pack_entry e;
2133         void *data;
2134
2135         if (!find_pack_entry(sha1, &e))
2136                 return NULL;
2137         data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2138         if (!data) {
2139                 /*
2140                  * We're probably in deep shit, but let's try to fetch
2141                  * the required object anyway from another pack or loose.
2142                  * This should happen only in the presence of a corrupted
2143                  * pack, and is better than failing outright.
2144                  */
2145                 error("failed to read object %s at offset %"PRIuMAX" from %s",
2146                       sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2147                 mark_bad_packed_object(e.p, sha1);
2148                 data = read_object(sha1, type, size);
2149         }
2150         return data;
2151 }
2152
2153 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2154                       unsigned char *sha1)
2155 {
2156         struct cached_object *co;
2157
2158         hash_sha1_file(buf, len, typename(type), sha1);
2159         if (has_sha1_file(sha1) || find_cached_object(sha1))
2160                 return 0;
2161         if (cached_object_alloc <= cached_object_nr) {
2162                 cached_object_alloc = alloc_nr(cached_object_alloc);
2163                 cached_objects = xrealloc(cached_objects,
2164                                           sizeof(*cached_objects) *
2165                                           cached_object_alloc);
2166         }
2167         co = &cached_objects[cached_object_nr++];
2168         co->size = len;
2169         co->type = type;
2170         co->buf = xmalloc(len);
2171         memcpy(co->buf, buf, len);
2172         hashcpy(co->sha1, sha1);
2173         return 0;
2174 }
2175
2176 static void *read_object(const unsigned char *sha1, enum object_type *type,
2177                          unsigned long *size)
2178 {
2179         unsigned long mapsize;
2180         void *map, *buf;
2181         struct cached_object *co;
2182
2183         co = find_cached_object(sha1);
2184         if (co) {
2185                 *type = co->type;
2186                 *size = co->size;
2187                 return xmemdupz(co->buf, co->size);
2188         }
2189
2190         buf = read_packed_sha1(sha1, type, size);
2191         if (buf)
2192                 return buf;
2193         map = map_sha1_file(sha1, &mapsize);
2194         if (map) {
2195                 buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2196                 munmap(map, mapsize);
2197                 return buf;
2198         }
2199         reprepare_packed_git();
2200         return read_packed_sha1(sha1, type, size);
2201 }
2202
2203 /*
2204  * This function dies on corrupt objects; the callers who want to
2205  * deal with them should arrange to call read_object() and give error
2206  * messages themselves.
2207  */
2208 void *read_sha1_file_extended(const unsigned char *sha1,
2209                               enum object_type *type,
2210                               unsigned long *size,
2211                               unsigned flag)
2212 {
2213         void *data;
2214         char *path;
2215         const struct packed_git *p;
2216         const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
2217                 ? lookup_replace_object(sha1) : sha1;
2218
2219         errno = 0;
2220         data = read_object(repl, type, size);
2221         if (data)
2222                 return data;
2223
2224         if (errno && errno != ENOENT)
2225                 die_errno("failed to read object %s", sha1_to_hex(sha1));
2226
2227         /* die if we replaced an object with one that does not exist */
2228         if (repl != sha1)
2229                 die("replacement %s not found for %s",
2230                     sha1_to_hex(repl), sha1_to_hex(sha1));
2231
2232         if (has_loose_object(repl)) {
2233                 path = sha1_file_name(sha1);
2234                 die("loose object %s (stored in %s) is corrupt",
2235                     sha1_to_hex(repl), path);
2236         }
2237
2238         if ((p = has_packed_and_bad(repl)) != NULL)
2239                 die("packed object %s (stored in %s) is corrupt",
2240                     sha1_to_hex(repl), p->pack_name);
2241
2242         return NULL;
2243 }
2244
2245 void *read_object_with_reference(const unsigned char *sha1,
2246                                  const char *required_type_name,
2247                                  unsigned long *size,
2248                                  unsigned char *actual_sha1_return)
2249 {
2250         enum object_type type, required_type;
2251         void *buffer;
2252         unsigned long isize;
2253         unsigned char actual_sha1[20];
2254
2255         required_type = type_from_string(required_type_name);
2256         hashcpy(actual_sha1, sha1);
2257         while (1) {
2258                 int ref_length = -1;
2259                 const char *ref_type = NULL;
2260
2261                 buffer = read_sha1_file(actual_sha1, &type, &isize);
2262                 if (!buffer)
2263                         return NULL;
2264                 if (type == required_type) {
2265                         *size = isize;
2266                         if (actual_sha1_return)
2267                                 hashcpy(actual_sha1_return, actual_sha1);
2268                         return buffer;
2269                 }
2270                 /* Handle references */
2271                 else if (type == OBJ_COMMIT)
2272                         ref_type = "tree ";
2273                 else if (type == OBJ_TAG)
2274                         ref_type = "object ";
2275                 else {
2276                         free(buffer);
2277                         return NULL;
2278                 }
2279                 ref_length = strlen(ref_type);
2280
2281                 if (ref_length + 40 > isize ||
2282                     memcmp(buffer, ref_type, ref_length) ||
2283                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2284                         free(buffer);
2285                         return NULL;
2286                 }
2287                 free(buffer);
2288                 /* Now we have the ID of the referred-to object in
2289                  * actual_sha1.  Check again. */
2290         }
2291 }
2292
2293 static void write_sha1_file_prepare(const void *buf, unsigned long len,
2294                                     const char *type, unsigned char *sha1,
2295                                     char *hdr, int *hdrlen)
2296 {
2297         git_SHA_CTX c;
2298
2299         /* Generate the header */
2300         *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2301
2302         /* Sha1.. */
2303         git_SHA1_Init(&c);
2304         git_SHA1_Update(&c, hdr, *hdrlen);
2305         git_SHA1_Update(&c, buf, len);
2306         git_SHA1_Final(sha1, &c);
2307 }
2308
2309 /*
2310  * Move the just written object into its final resting place.
2311  * NEEDSWORK: this should be renamed to finalize_temp_file() as
2312  * "moving" is only a part of what it does, when no patch between
2313  * master to pu changes the call sites of this function.
2314  */
2315 int move_temp_to_file(const char *tmpfile, const char *filename)
2316 {
2317         int ret = 0;
2318
2319         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2320                 goto try_rename;
2321         else if (link(tmpfile, filename))
2322                 ret = errno;
2323
2324         /*
2325          * Coda hack - coda doesn't like cross-directory links,
2326          * so we fall back to a rename, which will mean that it
2327          * won't be able to check collisions, but that's not a
2328          * big deal.
2329          *
2330          * The same holds for FAT formatted media.
2331          *
2332          * When this succeeds, we just return.  We have nothing
2333          * left to unlink.
2334          */
2335         if (ret && ret != EEXIST) {
2336         try_rename:
2337                 if (!rename(tmpfile, filename))
2338                         goto out;
2339                 ret = errno;
2340         }
2341         unlink_or_warn(tmpfile);
2342         if (ret) {
2343                 if (ret != EEXIST) {
2344                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
2345                 }
2346                 /* FIXME!!! Collision check here ? */
2347         }
2348
2349 out:
2350         if (adjust_shared_perm(filename))
2351                 return error("unable to set permission to '%s'", filename);
2352         return 0;
2353 }
2354
2355 static int write_buffer(int fd, const void *buf, size_t len)
2356 {
2357         if (write_in_full(fd, buf, len) < 0)
2358                 return error("file write error (%s)", strerror(errno));
2359         return 0;
2360 }
2361
2362 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2363                    unsigned char *sha1)
2364 {
2365         char hdr[32];
2366         int hdrlen;
2367         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2368         return 0;
2369 }
2370
2371 /* Finalize a file on disk, and close it. */
2372 static void close_sha1_file(int fd)
2373 {
2374         if (fsync_object_files)
2375                 fsync_or_die(fd, "sha1 file");
2376         if (close(fd) != 0)
2377                 die_errno("error when closing sha1 file");
2378 }
2379
2380 /* Size of directory component, including the ending '/' */
2381 static inline int directory_size(const char *filename)
2382 {
2383         const char *s = strrchr(filename, '/');
2384         if (!s)
2385                 return 0;
2386         return s - filename + 1;
2387 }
2388
2389 /*
2390  * This creates a temporary file in the same directory as the final
2391  * 'filename'
2392  *
2393  * We want to avoid cross-directory filename renames, because those
2394  * can have problems on various filesystems (FAT, NFS, Coda).
2395  */
2396 static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2397 {
2398         int fd, dirlen = directory_size(filename);
2399
2400         if (dirlen + 20 > bufsiz) {
2401                 errno = ENAMETOOLONG;
2402                 return -1;
2403         }
2404         memcpy(buffer, filename, dirlen);
2405         strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2406         fd = git_mkstemp_mode(buffer, 0444);
2407         if (fd < 0 && dirlen && errno == ENOENT) {
2408                 /* Make sure the directory exists */
2409                 memcpy(buffer, filename, dirlen);
2410                 buffer[dirlen-1] = 0;
2411                 if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2412                         return -1;
2413
2414                 /* Try again */
2415                 strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2416                 fd = git_mkstemp_mode(buffer, 0444);
2417         }
2418         return fd;
2419 }
2420
2421 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2422                               const void *buf, unsigned long len, time_t mtime)
2423 {
2424         int fd, ret;
2425         unsigned char compressed[4096];
2426         z_stream stream;
2427         git_SHA_CTX c;
2428         unsigned char parano_sha1[20];
2429         char *filename;
2430         static char tmpfile[PATH_MAX];
2431
2432         filename = sha1_file_name(sha1);
2433         fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2434         if (fd < 0) {
2435                 if (errno == EACCES)
2436                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
2437                 else
2438                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
2439         }
2440
2441         /* Set it up */
2442         memset(&stream, 0, sizeof(stream));
2443         deflateInit(&stream, zlib_compression_level);
2444         stream.next_out = compressed;
2445         stream.avail_out = sizeof(compressed);
2446         git_SHA1_Init(&c);
2447
2448         /* First header.. */
2449         stream.next_in = (unsigned char *)hdr;
2450         stream.avail_in = hdrlen;
2451         while (deflate(&stream, 0) == Z_OK)
2452                 /* nothing */;
2453         git_SHA1_Update(&c, hdr, hdrlen);
2454
2455         /* Then the data itself.. */
2456         stream.next_in = (void *)buf;
2457         stream.avail_in = len;
2458         do {
2459                 unsigned char *in0 = stream.next_in;
2460                 ret = deflate(&stream, Z_FINISH);
2461                 git_SHA1_Update(&c, in0, stream.next_in - in0);
2462                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2463                         die("unable to write sha1 file");
2464                 stream.next_out = compressed;
2465                 stream.avail_out = sizeof(compressed);
2466         } while (ret == Z_OK);
2467
2468         if (ret != Z_STREAM_END)
2469                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2470         ret = deflateEnd(&stream);
2471         if (ret != Z_OK)
2472                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2473         git_SHA1_Final(parano_sha1, &c);
2474         if (hashcmp(sha1, parano_sha1) != 0)
2475                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2476
2477         close_sha1_file(fd);
2478
2479         if (mtime) {
2480                 struct utimbuf utb;
2481                 utb.actime = mtime;
2482                 utb.modtime = mtime;
2483                 if (utime(tmpfile, &utb) < 0)
2484                         warning("failed utime() on %s: %s",
2485                                 tmpfile, strerror(errno));
2486         }
2487
2488         return move_temp_to_file(tmpfile, filename);
2489 }
2490
2491 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2492 {
2493         unsigned char sha1[20];
2494         char hdr[32];
2495         int hdrlen;
2496
2497         /* Normally if we have it in the pack then we do not bother writing
2498          * it out into .git/objects/??/?{38} file.
2499          */
2500         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2501         if (returnsha1)
2502                 hashcpy(returnsha1, sha1);
2503         if (has_sha1_file(sha1))
2504                 return 0;
2505         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2506 }
2507
2508 int force_object_loose(const unsigned char *sha1, time_t mtime)
2509 {
2510         void *buf;
2511         unsigned long len;
2512         enum object_type type;
2513         char hdr[32];
2514         int hdrlen;
2515         int ret;
2516
2517         if (has_loose_object(sha1))
2518                 return 0;
2519         buf = read_packed_sha1(sha1, &type, &len);
2520         if (!buf)
2521                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2522         hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2523         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2524         free(buf);
2525
2526         return ret;
2527 }
2528
2529 int has_pack_index(const unsigned char *sha1)
2530 {
2531         struct stat st;
2532         if (stat(sha1_pack_index_name(sha1), &st))
2533                 return 0;
2534         return 1;
2535 }
2536
2537 int has_sha1_pack(const unsigned char *sha1)
2538 {
2539         struct pack_entry e;
2540         return find_pack_entry(sha1, &e);
2541 }
2542
2543 int has_sha1_file(const unsigned char *sha1)
2544 {
2545         struct pack_entry e;
2546
2547         if (find_pack_entry(sha1, &e))
2548                 return 1;
2549         return has_loose_object(sha1);
2550 }
2551
2552 static void check_tree(const void *buf, size_t size)
2553 {
2554         struct tree_desc desc;
2555         struct name_entry entry;
2556
2557         init_tree_desc(&desc, buf, size);
2558         while (tree_entry(&desc, &entry))
2559                 /* do nothing
2560                  * tree_entry() will die() on malformed entries */
2561                 ;
2562 }
2563
2564 static void check_commit(const void *buf, size_t size)
2565 {
2566         struct commit c;
2567         memset(&c, 0, sizeof(c));
2568         if (parse_commit_buffer(&c, buf, size))
2569                 die("corrupt commit");
2570 }
2571
2572 static void check_tag(const void *buf, size_t size)
2573 {
2574         struct tag t;
2575         memset(&t, 0, sizeof(t));
2576         if (parse_tag_buffer(&t, buf, size))
2577                 die("corrupt tag");
2578 }
2579
2580 static int index_mem(unsigned char *sha1, void *buf, size_t size,
2581                      int write_object, enum object_type type,
2582                      const char *path, int format_check)
2583 {
2584         int ret, re_allocated = 0;
2585
2586         if (!type)
2587                 type = OBJ_BLOB;
2588
2589         /*
2590          * Convert blobs to git internal format
2591          */
2592         if ((type == OBJ_BLOB) && path) {
2593                 struct strbuf nbuf = STRBUF_INIT;
2594                 if (convert_to_git(path, buf, size, &nbuf,
2595                                    write_object ? safe_crlf : 0)) {
2596                         buf = strbuf_detach(&nbuf, &size);
2597                         re_allocated = 1;
2598                 }
2599         }
2600         if (format_check) {
2601                 if (type == OBJ_TREE)
2602                         check_tree(buf, size);
2603                 if (type == OBJ_COMMIT)
2604                         check_commit(buf, size);
2605                 if (type == OBJ_TAG)
2606                         check_tag(buf, size);
2607         }
2608
2609         if (write_object)
2610                 ret = write_sha1_file(buf, size, typename(type), sha1);
2611         else
2612                 ret = hash_sha1_file(buf, size, typename(type), sha1);
2613         if (re_allocated)
2614                 free(buf);
2615         return ret;
2616 }
2617
2618 #define SMALL_FILE_SIZE (32*1024)
2619
2620 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
2621              enum object_type type, const char *path, int format_check)
2622 {
2623         int ret;
2624         size_t size = xsize_t(st->st_size);
2625
2626         if (!S_ISREG(st->st_mode)) {
2627                 struct strbuf sbuf = STRBUF_INIT;
2628                 if (strbuf_read(&sbuf, fd, 4096) >= 0)
2629                         ret = index_mem(sha1, sbuf.buf, sbuf.len, write_object,
2630                                         type, path, format_check);
2631                 else
2632                         ret = -1;
2633                 strbuf_release(&sbuf);
2634         } else if (!size) {
2635                 ret = index_mem(sha1, NULL, size, write_object, type, path,
2636                                 format_check);
2637         } else if (size <= SMALL_FILE_SIZE) {
2638                 char *buf = xmalloc(size);
2639                 if (size == read_in_full(fd, buf, size))
2640                         ret = index_mem(sha1, buf, size, write_object, type,
2641                                         path, format_check);
2642                 else
2643                         ret = error("short read %s", strerror(errno));
2644                 free(buf);
2645         } else {
2646                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2647                 ret = index_mem(sha1, buf, size, write_object, type, path,
2648                                 format_check);
2649                 munmap(buf, size);
2650         }
2651         close(fd);
2652         return ret;
2653 }
2654
2655 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2656 {
2657         int fd;
2658         struct strbuf sb = STRBUF_INIT;
2659
2660         switch (st->st_mode & S_IFMT) {
2661         case S_IFREG:
2662                 fd = open(path, O_RDONLY);
2663                 if (fd < 0)
2664                         return error("open(\"%s\"): %s", path,
2665                                      strerror(errno));
2666                 if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path, 0) < 0)
2667                         return error("%s: failed to insert into database",
2668                                      path);
2669                 break;
2670         case S_IFLNK:
2671                 if (strbuf_readlink(&sb, path, st->st_size)) {
2672                         char *errstr = strerror(errno);
2673                         return error("readlink(\"%s\"): %s", path,
2674                                      errstr);
2675                 }
2676                 if (!write_object)
2677                         hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
2678                 else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
2679                         return error("%s: failed to insert into database",
2680                                      path);
2681                 strbuf_release(&sb);
2682                 break;
2683         case S_IFDIR:
2684                 return resolve_gitlink_ref(path, "HEAD", sha1);
2685         default:
2686                 return error("%s: unsupported file type", path);
2687         }
2688         return 0;
2689 }
2690
2691 int read_pack_header(int fd, struct pack_header *header)
2692 {
2693         if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
2694                 /* "eof before pack header was fully read" */
2695                 return PH_ERROR_EOF;
2696
2697         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2698                 /* "protocol error (pack signature mismatch detected)" */
2699                 return PH_ERROR_PACK_SIGNATURE;
2700         if (!pack_version_ok(header->hdr_version))
2701                 /* "protocol error (pack version unsupported)" */
2702                 return PH_ERROR_PROTOCOL;
2703         return 0;
2704 }
2705
2706 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
2707 {
2708         enum object_type type = sha1_object_info(sha1, NULL);
2709         if (type < 0)
2710                 die("%s is not a valid object", sha1_to_hex(sha1));
2711         if (type != expect)
2712                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
2713                     typename(expect));
2714 }