packfile: add repository argument to find_pack_entry
[git] / packfile.c
1 #include "cache.h"
2 #include "list.h"
3 #include "pack.h"
4 #include "repository.h"
5 #include "dir.h"
6 #include "mergesort.h"
7 #include "packfile.h"
8 #include "delta.h"
9 #include "list.h"
10 #include "streaming.h"
11 #include "sha1-lookup.h"
12 #include "commit.h"
13 #include "object.h"
14 #include "tag.h"
15 #include "tree-walk.h"
16 #include "tree.h"
17 #include "object-store.h"
18
19 char *odb_pack_name(struct strbuf *buf,
20                     const unsigned char *sha1,
21                     const char *ext)
22 {
23         strbuf_reset(buf);
24         strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
25                     sha1_to_hex(sha1), ext);
26         return buf->buf;
27 }
28
29 char *sha1_pack_name(const unsigned char *sha1)
30 {
31         static struct strbuf buf = STRBUF_INIT;
32         return odb_pack_name(&buf, sha1, "pack");
33 }
34
35 char *sha1_pack_index_name(const unsigned char *sha1)
36 {
37         static struct strbuf buf = STRBUF_INIT;
38         return odb_pack_name(&buf, sha1, "idx");
39 }
40
41 static unsigned int pack_used_ctr;
42 static unsigned int pack_mmap_calls;
43 static unsigned int peak_pack_open_windows;
44 static unsigned int pack_open_windows;
45 static unsigned int pack_open_fds;
46 static unsigned int pack_max_fds;
47 static size_t peak_pack_mapped;
48 static size_t pack_mapped;
49
50 #define SZ_FMT PRIuMAX
51 static inline uintmax_t sz_fmt(size_t s) { return s; }
52
53 void pack_report(void)
54 {
55         fprintf(stderr,
56                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
57                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
58                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
59                 sz_fmt(getpagesize()),
60                 sz_fmt(packed_git_window_size),
61                 sz_fmt(packed_git_limit));
62         fprintf(stderr,
63                 "pack_report: pack_used_ctr            = %10u\n"
64                 "pack_report: pack_mmap_calls          = %10u\n"
65                 "pack_report: pack_open_windows        = %10u / %10u\n"
66                 "pack_report: pack_mapped              = "
67                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
68                 pack_used_ctr,
69                 pack_mmap_calls,
70                 pack_open_windows, peak_pack_open_windows,
71                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
72 }
73
74 /*
75  * Open and mmap the index file at path, perform a couple of
76  * consistency checks, then record its information to p.  Return 0 on
77  * success.
78  */
79 static int check_packed_git_idx(const char *path, struct packed_git *p)
80 {
81         void *idx_map;
82         struct pack_idx_header *hdr;
83         size_t idx_size;
84         uint32_t version, nr, i, *index;
85         int fd = git_open(path);
86         struct stat st;
87
88         if (fd < 0)
89                 return -1;
90         if (fstat(fd, &st)) {
91                 close(fd);
92                 return -1;
93         }
94         idx_size = xsize_t(st.st_size);
95         if (idx_size < 4 * 256 + 20 + 20) {
96                 close(fd);
97                 return error("index file %s is too small", path);
98         }
99         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
100         close(fd);
101
102         hdr = idx_map;
103         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
104                 version = ntohl(hdr->idx_version);
105                 if (version < 2 || version > 2) {
106                         munmap(idx_map, idx_size);
107                         return error("index file %s is version %"PRIu32
108                                      " and is not supported by this binary"
109                                      " (try upgrading GIT to a newer version)",
110                                      path, version);
111                 }
112         } else
113                 version = 1;
114
115         nr = 0;
116         index = idx_map;
117         if (version > 1)
118                 index += 2;  /* skip index header */
119         for (i = 0; i < 256; i++) {
120                 uint32_t n = ntohl(index[i]);
121                 if (n < nr) {
122                         munmap(idx_map, idx_size);
123                         return error("non-monotonic index %s", path);
124                 }
125                 nr = n;
126         }
127
128         if (version == 1) {
129                 /*
130                  * Total size:
131                  *  - 256 index entries 4 bytes each
132                  *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
133                  *  - 20-byte SHA1 of the packfile
134                  *  - 20-byte SHA1 file checksum
135                  */
136                 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
137                         munmap(idx_map, idx_size);
138                         return error("wrong index v1 file size in %s", path);
139                 }
140         } else if (version == 2) {
141                 /*
142                  * Minimum size:
143                  *  - 8 bytes of header
144                  *  - 256 index entries 4 bytes each
145                  *  - 20-byte sha1 entry * nr
146                  *  - 4-byte crc entry * nr
147                  *  - 4-byte offset entry * nr
148                  *  - 20-byte SHA1 of the packfile
149                  *  - 20-byte SHA1 file checksum
150                  * And after the 4-byte offset table might be a
151                  * variable sized table containing 8-byte entries
152                  * for offsets larger than 2^31.
153                  */
154                 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
155                 unsigned long max_size = min_size;
156                 if (nr)
157                         max_size += (nr - 1)*8;
158                 if (idx_size < min_size || idx_size > max_size) {
159                         munmap(idx_map, idx_size);
160                         return error("wrong index v2 file size in %s", path);
161                 }
162                 if (idx_size != min_size &&
163                     /*
164                      * make sure we can deal with large pack offsets.
165                      * 31-bit signed offset won't be enough, neither
166                      * 32-bit unsigned one will be.
167                      */
168                     (sizeof(off_t) <= 4)) {
169                         munmap(idx_map, idx_size);
170                         return error("pack too large for current definition of off_t in %s", path);
171                 }
172         }
173
174         p->index_version = version;
175         p->index_data = idx_map;
176         p->index_size = idx_size;
177         p->num_objects = nr;
178         return 0;
179 }
180
181 int open_pack_index(struct packed_git *p)
182 {
183         char *idx_name;
184         size_t len;
185         int ret;
186
187         if (p->index_data)
188                 return 0;
189
190         if (!strip_suffix(p->pack_name, ".pack", &len))
191                 die("BUG: pack_name does not end in .pack");
192         idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
193         ret = check_packed_git_idx(idx_name, p);
194         free(idx_name);
195         return ret;
196 }
197
198 static struct packed_git *alloc_packed_git(int extra)
199 {
200         struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
201         memset(p, 0, sizeof(*p));
202         p->pack_fd = -1;
203         return p;
204 }
205
206 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
207 {
208         const char *path = sha1_pack_name(sha1);
209         size_t alloc = st_add(strlen(path), 1);
210         struct packed_git *p = alloc_packed_git(alloc);
211
212         memcpy(p->pack_name, path, alloc); /* includes NUL */
213         hashcpy(p->sha1, sha1);
214         if (check_packed_git_idx(idx_path, p)) {
215                 free(p);
216                 return NULL;
217         }
218
219         return p;
220 }
221
222 static void scan_windows(struct packed_git *p,
223         struct packed_git **lru_p,
224         struct pack_window **lru_w,
225         struct pack_window **lru_l)
226 {
227         struct pack_window *w, *w_l;
228
229         for (w_l = NULL, w = p->windows; w; w = w->next) {
230                 if (!w->inuse_cnt) {
231                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
232                                 *lru_p = p;
233                                 *lru_w = w;
234                                 *lru_l = w_l;
235                         }
236                 }
237                 w_l = w;
238         }
239 }
240
241 static int unuse_one_window(struct packed_git *current)
242 {
243         struct packed_git *p, *lru_p = NULL;
244         struct pack_window *lru_w = NULL, *lru_l = NULL;
245
246         if (current)
247                 scan_windows(current, &lru_p, &lru_w, &lru_l);
248         for (p = the_repository->objects->packed_git; p; p = p->next)
249                 scan_windows(p, &lru_p, &lru_w, &lru_l);
250         if (lru_p) {
251                 munmap(lru_w->base, lru_w->len);
252                 pack_mapped -= lru_w->len;
253                 if (lru_l)
254                         lru_l->next = lru_w->next;
255                 else
256                         lru_p->windows = lru_w->next;
257                 free(lru_w);
258                 pack_open_windows--;
259                 return 1;
260         }
261         return 0;
262 }
263
264 void release_pack_memory(size_t need)
265 {
266         size_t cur = pack_mapped;
267         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
268                 ; /* nothing */
269 }
270
271 void close_pack_windows(struct packed_git *p)
272 {
273         while (p->windows) {
274                 struct pack_window *w = p->windows;
275
276                 if (w->inuse_cnt)
277                         die("pack '%s' still has open windows to it",
278                             p->pack_name);
279                 munmap(w->base, w->len);
280                 pack_mapped -= w->len;
281                 pack_open_windows--;
282                 p->windows = w->next;
283                 free(w);
284         }
285 }
286
287 static int close_pack_fd(struct packed_git *p)
288 {
289         if (p->pack_fd < 0)
290                 return 0;
291
292         close(p->pack_fd);
293         pack_open_fds--;
294         p->pack_fd = -1;
295
296         return 1;
297 }
298
299 void close_pack_index(struct packed_git *p)
300 {
301         if (p->index_data) {
302                 munmap((void *)p->index_data, p->index_size);
303                 p->index_data = NULL;
304         }
305 }
306
307 static void close_pack(struct packed_git *p)
308 {
309         close_pack_windows(p);
310         close_pack_fd(p);
311         close_pack_index(p);
312 }
313
314 void close_all_packs(struct raw_object_store *o)
315 {
316         struct packed_git *p;
317
318         for (p = o->packed_git; p; p = p->next)
319                 if (p->do_not_close)
320                         die("BUG: want to close pack marked 'do-not-close'");
321                 else
322                         close_pack(p);
323 }
324
325 /*
326  * The LRU pack is the one with the oldest MRU window, preferring packs
327  * with no used windows, or the oldest mtime if it has no windows allocated.
328  */
329 static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
330 {
331         struct pack_window *w, *this_mru_w;
332         int has_windows_inuse = 0;
333
334         /*
335          * Reject this pack if it has windows and the previously selected
336          * one does not.  If this pack does not have windows, reject
337          * it if the pack file is newer than the previously selected one.
338          */
339         if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
340                 return;
341
342         for (w = this_mru_w = p->windows; w; w = w->next) {
343                 /*
344                  * Reject this pack if any of its windows are in use,
345                  * but the previously selected pack did not have any
346                  * inuse windows.  Otherwise, record that this pack
347                  * has windows in use.
348                  */
349                 if (w->inuse_cnt) {
350                         if (*accept_windows_inuse)
351                                 has_windows_inuse = 1;
352                         else
353                                 return;
354                 }
355
356                 if (w->last_used > this_mru_w->last_used)
357                         this_mru_w = w;
358
359                 /*
360                  * Reject this pack if it has windows that have been
361                  * used more recently than the previously selected pack.
362                  * If the previously selected pack had windows inuse and
363                  * we have not encountered a window in this pack that is
364                  * inuse, skip this check since we prefer a pack with no
365                  * inuse windows to one that has inuse windows.
366                  */
367                 if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
368                     this_mru_w->last_used > (*mru_w)->last_used)
369                         return;
370         }
371
372         /*
373          * Select this pack.
374          */
375         *mru_w = this_mru_w;
376         *lru_p = p;
377         *accept_windows_inuse = has_windows_inuse;
378 }
379
380 static int close_one_pack(void)
381 {
382         struct packed_git *p, *lru_p = NULL;
383         struct pack_window *mru_w = NULL;
384         int accept_windows_inuse = 1;
385
386         for (p = the_repository->objects->packed_git; p; p = p->next) {
387                 if (p->pack_fd == -1)
388                         continue;
389                 find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
390         }
391
392         if (lru_p)
393                 return close_pack_fd(lru_p);
394
395         return 0;
396 }
397
398 static unsigned int get_max_fd_limit(void)
399 {
400 #ifdef RLIMIT_NOFILE
401         {
402                 struct rlimit lim;
403
404                 if (!getrlimit(RLIMIT_NOFILE, &lim))
405                         return lim.rlim_cur;
406         }
407 #endif
408
409 #ifdef _SC_OPEN_MAX
410         {
411                 long open_max = sysconf(_SC_OPEN_MAX);
412                 if (0 < open_max)
413                         return open_max;
414                 /*
415                  * Otherwise, we got -1 for one of the two
416                  * reasons:
417                  *
418                  * (1) sysconf() did not understand _SC_OPEN_MAX
419                  *     and signaled an error with -1; or
420                  * (2) sysconf() said there is no limit.
421                  *
422                  * We _could_ clear errno before calling sysconf() to
423                  * tell these two cases apart and return a huge number
424                  * in the latter case to let the caller cap it to a
425                  * value that is not so selfish, but letting the
426                  * fallback OPEN_MAX codepath take care of these cases
427                  * is a lot simpler.
428                  */
429         }
430 #endif
431
432 #ifdef OPEN_MAX
433         return OPEN_MAX;
434 #else
435         return 1; /* see the caller ;-) */
436 #endif
437 }
438
439 /*
440  * Do not call this directly as this leaks p->pack_fd on error return;
441  * call open_packed_git() instead.
442  */
443 static int open_packed_git_1(struct packed_git *p)
444 {
445         struct stat st;
446         struct pack_header hdr;
447         unsigned char sha1[20];
448         unsigned char *idx_sha1;
449         long fd_flag;
450         ssize_t read_result;
451
452         if (!p->index_data && open_pack_index(p))
453                 return error("packfile %s index unavailable", p->pack_name);
454
455         if (!pack_max_fds) {
456                 unsigned int max_fds = get_max_fd_limit();
457
458                 /* Save 3 for stdin/stdout/stderr, 22 for work */
459                 if (25 < max_fds)
460                         pack_max_fds = max_fds - 25;
461                 else
462                         pack_max_fds = 1;
463         }
464
465         while (pack_max_fds <= pack_open_fds && close_one_pack())
466                 ; /* nothing */
467
468         p->pack_fd = git_open(p->pack_name);
469         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
470                 return -1;
471         pack_open_fds++;
472
473         /* If we created the struct before we had the pack we lack size. */
474         if (!p->pack_size) {
475                 if (!S_ISREG(st.st_mode))
476                         return error("packfile %s not a regular file", p->pack_name);
477                 p->pack_size = st.st_size;
478         } else if (p->pack_size != st.st_size)
479                 return error("packfile %s size changed", p->pack_name);
480
481         /* We leave these file descriptors open with sliding mmap;
482          * there is no point keeping them open across exec(), though.
483          */
484         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
485         if (fd_flag < 0)
486                 return error("cannot determine file descriptor flags");
487         fd_flag |= FD_CLOEXEC;
488         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
489                 return error("cannot set FD_CLOEXEC");
490
491         /* Verify we recognize this pack file format. */
492         read_result = read_in_full(p->pack_fd, &hdr, sizeof(hdr));
493         if (read_result < 0)
494                 return error_errno("error reading from %s", p->pack_name);
495         if (read_result != sizeof(hdr))
496                 return error("file %s is far too short to be a packfile", p->pack_name);
497         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
498                 return error("file %s is not a GIT packfile", p->pack_name);
499         if (!pack_version_ok(hdr.hdr_version))
500                 return error("packfile %s is version %"PRIu32" and not"
501                         " supported (try upgrading GIT to a newer version)",
502                         p->pack_name, ntohl(hdr.hdr_version));
503
504         /* Verify the pack matches its index. */
505         if (p->num_objects != ntohl(hdr.hdr_entries))
506                 return error("packfile %s claims to have %"PRIu32" objects"
507                              " while index indicates %"PRIu32" objects",
508                              p->pack_name, ntohl(hdr.hdr_entries),
509                              p->num_objects);
510         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
511                 return error("end of packfile %s is unavailable", p->pack_name);
512         read_result = read_in_full(p->pack_fd, sha1, sizeof(sha1));
513         if (read_result < 0)
514                 return error_errno("error reading from %s", p->pack_name);
515         if (read_result != sizeof(sha1))
516                 return error("packfile %s signature is unavailable", p->pack_name);
517         idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
518         if (hashcmp(sha1, idx_sha1))
519                 return error("packfile %s does not match index", p->pack_name);
520         return 0;
521 }
522
523 static int open_packed_git(struct packed_git *p)
524 {
525         if (!open_packed_git_1(p))
526                 return 0;
527         close_pack_fd(p);
528         return -1;
529 }
530
531 static int in_window(struct pack_window *win, off_t offset)
532 {
533         /* We must promise at least 20 bytes (one hash) after the
534          * offset is available from this window, otherwise the offset
535          * is not actually in this window and a different window (which
536          * has that one hash excess) must be used.  This is to support
537          * the object header and delta base parsing routines below.
538          */
539         off_t win_off = win->offset;
540         return win_off <= offset
541                 && (offset + 20) <= (win_off + win->len);
542 }
543
544 unsigned char *use_pack(struct packed_git *p,
545                 struct pack_window **w_cursor,
546                 off_t offset,
547                 unsigned long *left)
548 {
549         struct pack_window *win = *w_cursor;
550
551         /* Since packfiles end in a hash of their content and it's
552          * pointless to ask for an offset into the middle of that
553          * hash, and the in_window function above wouldn't match
554          * don't allow an offset too close to the end of the file.
555          */
556         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
557                 die("packfile %s cannot be accessed", p->pack_name);
558         if (offset > (p->pack_size - 20))
559                 die("offset beyond end of packfile (truncated pack?)");
560         if (offset < 0)
561                 die(_("offset before end of packfile (broken .idx?)"));
562
563         if (!win || !in_window(win, offset)) {
564                 if (win)
565                         win->inuse_cnt--;
566                 for (win = p->windows; win; win = win->next) {
567                         if (in_window(win, offset))
568                                 break;
569                 }
570                 if (!win) {
571                         size_t window_align = packed_git_window_size / 2;
572                         off_t len;
573
574                         if (p->pack_fd == -1 && open_packed_git(p))
575                                 die("packfile %s cannot be accessed", p->pack_name);
576
577                         win = xcalloc(1, sizeof(*win));
578                         win->offset = (offset / window_align) * window_align;
579                         len = p->pack_size - win->offset;
580                         if (len > packed_git_window_size)
581                                 len = packed_git_window_size;
582                         win->len = (size_t)len;
583                         pack_mapped += win->len;
584                         while (packed_git_limit < pack_mapped
585                                 && unuse_one_window(p))
586                                 ; /* nothing */
587                         win->base = xmmap(NULL, win->len,
588                                 PROT_READ, MAP_PRIVATE,
589                                 p->pack_fd, win->offset);
590                         if (win->base == MAP_FAILED)
591                                 die_errno("packfile %s cannot be mapped",
592                                           p->pack_name);
593                         if (!win->offset && win->len == p->pack_size
594                                 && !p->do_not_close)
595                                 close_pack_fd(p);
596                         pack_mmap_calls++;
597                         pack_open_windows++;
598                         if (pack_mapped > peak_pack_mapped)
599                                 peak_pack_mapped = pack_mapped;
600                         if (pack_open_windows > peak_pack_open_windows)
601                                 peak_pack_open_windows = pack_open_windows;
602                         win->next = p->windows;
603                         p->windows = win;
604                 }
605         }
606         if (win != *w_cursor) {
607                 win->last_used = pack_used_ctr++;
608                 win->inuse_cnt++;
609                 *w_cursor = win;
610         }
611         offset -= win->offset;
612         if (left)
613                 *left = win->len - xsize_t(offset);
614         return win->base + offset;
615 }
616
617 void unuse_pack(struct pack_window **w_cursor)
618 {
619         struct pack_window *w = *w_cursor;
620         if (w) {
621                 w->inuse_cnt--;
622                 *w_cursor = NULL;
623         }
624 }
625
626 static void try_to_free_pack_memory(size_t size)
627 {
628         release_pack_memory(size);
629 }
630
631 struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
632 {
633         static int have_set_try_to_free_routine;
634         struct stat st;
635         size_t alloc;
636         struct packed_git *p;
637
638         if (!have_set_try_to_free_routine) {
639                 have_set_try_to_free_routine = 1;
640                 set_try_to_free_routine(try_to_free_pack_memory);
641         }
642
643         /*
644          * Make sure a corresponding .pack file exists and that
645          * the index looks sane.
646          */
647         if (!strip_suffix_mem(path, &path_len, ".idx"))
648                 return NULL;
649
650         /*
651          * ".promisor" is long enough to hold any suffix we're adding (and
652          * the use xsnprintf double-checks that)
653          */
654         alloc = st_add3(path_len, strlen(".promisor"), 1);
655         p = alloc_packed_git(alloc);
656         memcpy(p->pack_name, path, path_len);
657
658         xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
659         if (!access(p->pack_name, F_OK))
660                 p->pack_keep = 1;
661
662         xsnprintf(p->pack_name + path_len, alloc - path_len, ".promisor");
663         if (!access(p->pack_name, F_OK))
664                 p->pack_promisor = 1;
665
666         xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
667         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
668                 free(p);
669                 return NULL;
670         }
671
672         /* ok, it looks sane as far as we can check without
673          * actually mapping the pack file.
674          */
675         p->pack_size = st.st_size;
676         p->pack_local = local;
677         p->mtime = st.st_mtime;
678         if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
679                 hashclr(p->sha1);
680         return p;
681 }
682
683 void install_packed_git(struct repository *r, struct packed_git *pack)
684 {
685         if (pack->pack_fd != -1)
686                 pack_open_fds++;
687
688         pack->next = r->objects->packed_git;
689         r->objects->packed_git = pack;
690 }
691
692 void (*report_garbage)(unsigned seen_bits, const char *path);
693
694 static void report_helper(const struct string_list *list,
695                           int seen_bits, int first, int last)
696 {
697         if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
698                 return;
699
700         for (; first < last; first++)
701                 report_garbage(seen_bits, list->items[first].string);
702 }
703
704 static void report_pack_garbage(struct string_list *list)
705 {
706         int i, baselen = -1, first = 0, seen_bits = 0;
707
708         if (!report_garbage)
709                 return;
710
711         string_list_sort(list);
712
713         for (i = 0; i < list->nr; i++) {
714                 const char *path = list->items[i].string;
715                 if (baselen != -1 &&
716                     strncmp(path, list->items[first].string, baselen)) {
717                         report_helper(list, seen_bits, first, i);
718                         baselen = -1;
719                         seen_bits = 0;
720                 }
721                 if (baselen == -1) {
722                         const char *dot = strrchr(path, '.');
723                         if (!dot) {
724                                 report_garbage(PACKDIR_FILE_GARBAGE, path);
725                                 continue;
726                         }
727                         baselen = dot - path + 1;
728                         first = i;
729                 }
730                 if (!strcmp(path + baselen, "pack"))
731                         seen_bits |= 1;
732                 else if (!strcmp(path + baselen, "idx"))
733                         seen_bits |= 2;
734         }
735         report_helper(list, seen_bits, first, list->nr);
736 }
737
738 static void prepare_packed_git_one(struct repository *r, char *objdir, int local)
739 {
740         struct strbuf path = STRBUF_INIT;
741         size_t dirnamelen;
742         DIR *dir;
743         struct dirent *de;
744         struct string_list garbage = STRING_LIST_INIT_DUP;
745
746         strbuf_addstr(&path, objdir);
747         strbuf_addstr(&path, "/pack");
748         dir = opendir(path.buf);
749         if (!dir) {
750                 if (errno != ENOENT)
751                         error_errno("unable to open object pack directory: %s",
752                                     path.buf);
753                 strbuf_release(&path);
754                 return;
755         }
756         strbuf_addch(&path, '/');
757         dirnamelen = path.len;
758         while ((de = readdir(dir)) != NULL) {
759                 struct packed_git *p;
760                 size_t base_len;
761
762                 if (is_dot_or_dotdot(de->d_name))
763                         continue;
764
765                 strbuf_setlen(&path, dirnamelen);
766                 strbuf_addstr(&path, de->d_name);
767
768                 base_len = path.len;
769                 if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
770                         /* Don't reopen a pack we already have. */
771                         for (p = r->objects->packed_git; p;
772                              p = p->next) {
773                                 size_t len;
774                                 if (strip_suffix(p->pack_name, ".pack", &len) &&
775                                     len == base_len &&
776                                     !memcmp(p->pack_name, path.buf, len))
777                                         break;
778                         }
779                         if (p == NULL &&
780                             /*
781                              * See if it really is a valid .idx file with
782                              * corresponding .pack file that we can map.
783                              */
784                             (p = add_packed_git(path.buf, path.len, local)) != NULL)
785                                 install_packed_git(r, p);
786                 }
787
788                 if (!report_garbage)
789                         continue;
790
791                 if (ends_with(de->d_name, ".idx") ||
792                     ends_with(de->d_name, ".pack") ||
793                     ends_with(de->d_name, ".bitmap") ||
794                     ends_with(de->d_name, ".keep") ||
795                     ends_with(de->d_name, ".promisor"))
796                         string_list_append(&garbage, path.buf);
797                 else
798                         report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
799         }
800         closedir(dir);
801         report_pack_garbage(&garbage);
802         string_list_clear(&garbage, 0);
803         strbuf_release(&path);
804 }
805
806 /*
807  * Give a fast, rough count of the number of objects in the repository. This
808  * ignores loose objects completely. If you have a lot of them, then either
809  * you should repack because your performance will be awful, or they are
810  * all unreachable objects about to be pruned, in which case they're not really
811  * interesting as a measure of repo size in the first place.
812  */
813 unsigned long approximate_object_count(void)
814 {
815         if (!the_repository->objects->approximate_object_count_valid) {
816                 unsigned long count;
817                 struct packed_git *p;
818
819                 prepare_packed_git(the_repository);
820                 count = 0;
821                 for (p = the_repository->objects->packed_git; p; p = p->next) {
822                         if (open_pack_index(p))
823                                 continue;
824                         count += p->num_objects;
825                 }
826                 the_repository->objects->approximate_object_count = count;
827         }
828         return the_repository->objects->approximate_object_count;
829 }
830
831 static void *get_next_packed_git(const void *p)
832 {
833         return ((const struct packed_git *)p)->next;
834 }
835
836 static void set_next_packed_git(void *p, void *next)
837 {
838         ((struct packed_git *)p)->next = next;
839 }
840
841 static int sort_pack(const void *a_, const void *b_)
842 {
843         const struct packed_git *a = a_;
844         const struct packed_git *b = b_;
845         int st;
846
847         /*
848          * Local packs tend to contain objects specific to our
849          * variant of the project than remote ones.  In addition,
850          * remote ones could be on a network mounted filesystem.
851          * Favor local ones for these reasons.
852          */
853         st = a->pack_local - b->pack_local;
854         if (st)
855                 return -st;
856
857         /*
858          * Younger packs tend to contain more recent objects,
859          * and more recent objects tend to get accessed more
860          * often.
861          */
862         if (a->mtime < b->mtime)
863                 return 1;
864         else if (a->mtime == b->mtime)
865                 return 0;
866         return -1;
867 }
868
869 static void rearrange_packed_git(struct repository *r)
870 {
871         r->objects->packed_git = llist_mergesort(
872                 r->objects->packed_git, get_next_packed_git,
873                 set_next_packed_git, sort_pack);
874 }
875
876 static void prepare_packed_git_mru(struct repository *r)
877 {
878         struct packed_git *p;
879
880         INIT_LIST_HEAD(&r->objects->packed_git_mru);
881
882         for (p = r->objects->packed_git; p; p = p->next)
883                 list_add_tail(&p->mru, &r->objects->packed_git_mru);
884 }
885
886 void prepare_packed_git(struct repository *r)
887 {
888         struct alternate_object_database *alt;
889
890         if (r->objects->packed_git_initialized)
891                 return;
892         prepare_packed_git_one(r, r->objects->objectdir, 1);
893         prepare_alt_odb(r);
894         for (alt = r->objects->alt_odb_list; alt; alt = alt->next)
895                 prepare_packed_git_one(r, alt->path, 0);
896         rearrange_packed_git(r);
897         prepare_packed_git_mru(r);
898         r->objects->packed_git_initialized = 1;
899 }
900
901 void reprepare_packed_git(struct repository *r)
902 {
903         r->objects->approximate_object_count_valid = 0;
904         r->objects->packed_git_initialized = 0;
905         prepare_packed_git(r);
906 }
907
908 struct packed_git *get_packed_git(struct repository *r)
909 {
910         return r->objects->packed_git;
911 }
912
913 struct list_head *get_packed_git_mru(struct repository *r)
914 {
915         return &r->objects->packed_git_mru;
916 }
917
918 unsigned long unpack_object_header_buffer(const unsigned char *buf,
919                 unsigned long len, enum object_type *type, unsigned long *sizep)
920 {
921         unsigned shift;
922         unsigned long size, c;
923         unsigned long used = 0;
924
925         c = buf[used++];
926         *type = (c >> 4) & 7;
927         size = c & 15;
928         shift = 4;
929         while (c & 0x80) {
930                 if (len <= used || bitsizeof(long) <= shift) {
931                         error("bad object header");
932                         size = used = 0;
933                         break;
934                 }
935                 c = buf[used++];
936                 size += (c & 0x7f) << shift;
937                 shift += 7;
938         }
939         *sizep = size;
940         return used;
941 }
942
943 unsigned long get_size_from_delta(struct packed_git *p,
944                                   struct pack_window **w_curs,
945                                   off_t curpos)
946 {
947         const unsigned char *data;
948         unsigned char delta_head[20], *in;
949         git_zstream stream;
950         int st;
951
952         memset(&stream, 0, sizeof(stream));
953         stream.next_out = delta_head;
954         stream.avail_out = sizeof(delta_head);
955
956         git_inflate_init(&stream);
957         do {
958                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
959                 stream.next_in = in;
960                 st = git_inflate(&stream, Z_FINISH);
961                 curpos += stream.next_in - in;
962         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
963                  stream.total_out < sizeof(delta_head));
964         git_inflate_end(&stream);
965         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
966                 error("delta data unpack-initial failed");
967                 return 0;
968         }
969
970         /* Examine the initial part of the delta to figure out
971          * the result size.
972          */
973         data = delta_head;
974
975         /* ignore base size */
976         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
977
978         /* Read the result size */
979         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
980 }
981
982 int unpack_object_header(struct packed_git *p,
983                          struct pack_window **w_curs,
984                          off_t *curpos,
985                          unsigned long *sizep)
986 {
987         unsigned char *base;
988         unsigned long left;
989         unsigned long used;
990         enum object_type type;
991
992         /* use_pack() assures us we have [base, base + 20) available
993          * as a range that we can look at.  (Its actually the hash
994          * size that is assured.)  With our object header encoding
995          * the maximum deflated object size is 2^137, which is just
996          * insane, so we know won't exceed what we have been given.
997          */
998         base = use_pack(p, w_curs, *curpos, &left);
999         used = unpack_object_header_buffer(base, left, &type, sizep);
1000         if (!used) {
1001                 type = OBJ_BAD;
1002         } else
1003                 *curpos += used;
1004
1005         return type;
1006 }
1007
1008 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
1009 {
1010         unsigned i;
1011         for (i = 0; i < p->num_bad_objects; i++)
1012                 if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
1013                         return;
1014         p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1015                                       st_mult(GIT_MAX_RAWSZ,
1016                                               st_add(p->num_bad_objects, 1)));
1017         hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
1018         p->num_bad_objects++;
1019 }
1020
1021 const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1022 {
1023         struct packed_git *p;
1024         unsigned i;
1025
1026         for (p = the_repository->objects->packed_git; p; p = p->next)
1027                 for (i = 0; i < p->num_bad_objects; i++)
1028                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1029                                 return p;
1030         return NULL;
1031 }
1032
1033 static off_t get_delta_base(struct packed_git *p,
1034                                     struct pack_window **w_curs,
1035                                     off_t *curpos,
1036                                     enum object_type type,
1037                                     off_t delta_obj_offset)
1038 {
1039         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1040         off_t base_offset;
1041
1042         /* use_pack() assured us we have [base_info, base_info + 20)
1043          * as a range that we can look at without walking off the
1044          * end of the mapped window.  Its actually the hash size
1045          * that is assured.  An OFS_DELTA longer than the hash size
1046          * is stupid, as then a REF_DELTA would be smaller to store.
1047          */
1048         if (type == OBJ_OFS_DELTA) {
1049                 unsigned used = 0;
1050                 unsigned char c = base_info[used++];
1051                 base_offset = c & 127;
1052                 while (c & 128) {
1053                         base_offset += 1;
1054                         if (!base_offset || MSB(base_offset, 7))
1055                                 return 0;  /* overflow */
1056                         c = base_info[used++];
1057                         base_offset = (base_offset << 7) + (c & 127);
1058                 }
1059                 base_offset = delta_obj_offset - base_offset;
1060                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1061                         return 0;  /* out of bound */
1062                 *curpos += used;
1063         } else if (type == OBJ_REF_DELTA) {
1064                 /* The base entry _must_ be in the same pack */
1065                 base_offset = find_pack_entry_one(base_info, p);
1066                 *curpos += 20;
1067         } else
1068                 die("I am totally screwed");
1069         return base_offset;
1070 }
1071
1072 /*
1073  * Like get_delta_base above, but we return the sha1 instead of the pack
1074  * offset. This means it is cheaper for REF deltas (we do not have to do
1075  * the final object lookup), but more expensive for OFS deltas (we
1076  * have to load the revidx to convert the offset back into a sha1).
1077  */
1078 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1079                                                 struct pack_window **w_curs,
1080                                                 off_t curpos,
1081                                                 enum object_type type,
1082                                                 off_t delta_obj_offset)
1083 {
1084         if (type == OBJ_REF_DELTA) {
1085                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1086                 return base;
1087         } else if (type == OBJ_OFS_DELTA) {
1088                 struct revindex_entry *revidx;
1089                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1090                                                    type, delta_obj_offset);
1091
1092                 if (!base_offset)
1093                         return NULL;
1094
1095                 revidx = find_pack_revindex(p, base_offset);
1096                 if (!revidx)
1097                         return NULL;
1098
1099                 return nth_packed_object_sha1(p, revidx->nr);
1100         } else
1101                 return NULL;
1102 }
1103
1104 static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1105 {
1106         int type;
1107         struct revindex_entry *revidx;
1108         const unsigned char *sha1;
1109         revidx = find_pack_revindex(p, obj_offset);
1110         if (!revidx)
1111                 return OBJ_BAD;
1112         sha1 = nth_packed_object_sha1(p, revidx->nr);
1113         mark_bad_packed_object(p, sha1);
1114         type = sha1_object_info(sha1, NULL);
1115         if (type <= OBJ_NONE)
1116                 return OBJ_BAD;
1117         return type;
1118 }
1119
1120 #define POI_STACK_PREALLOC 64
1121
1122 static enum object_type packed_to_object_type(struct packed_git *p,
1123                                               off_t obj_offset,
1124                                               enum object_type type,
1125                                               struct pack_window **w_curs,
1126                                               off_t curpos)
1127 {
1128         off_t small_poi_stack[POI_STACK_PREALLOC];
1129         off_t *poi_stack = small_poi_stack;
1130         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1131
1132         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1133                 off_t base_offset;
1134                 unsigned long size;
1135                 /* Push the object we're going to leave behind */
1136                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1137                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1138                         ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1139                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1140                 } else {
1141                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1142                 }
1143                 poi_stack[poi_stack_nr++] = obj_offset;
1144                 /* If parsing the base offset fails, just unwind */
1145                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1146                 if (!base_offset)
1147                         goto unwind;
1148                 curpos = obj_offset = base_offset;
1149                 type = unpack_object_header(p, w_curs, &curpos, &size);
1150                 if (type <= OBJ_NONE) {
1151                         /* If getting the base itself fails, we first
1152                          * retry the base, otherwise unwind */
1153                         type = retry_bad_packed_offset(p, base_offset);
1154                         if (type > OBJ_NONE)
1155                                 goto out;
1156                         goto unwind;
1157                 }
1158         }
1159
1160         switch (type) {
1161         case OBJ_BAD:
1162         case OBJ_COMMIT:
1163         case OBJ_TREE:
1164         case OBJ_BLOB:
1165         case OBJ_TAG:
1166                 break;
1167         default:
1168                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1169                       type, (uintmax_t)obj_offset, p->pack_name);
1170                 type = OBJ_BAD;
1171         }
1172
1173 out:
1174         if (poi_stack != small_poi_stack)
1175                 free(poi_stack);
1176         return type;
1177
1178 unwind:
1179         while (poi_stack_nr) {
1180                 obj_offset = poi_stack[--poi_stack_nr];
1181                 type = retry_bad_packed_offset(p, obj_offset);
1182                 if (type > OBJ_NONE)
1183                         goto out;
1184         }
1185         type = OBJ_BAD;
1186         goto out;
1187 }
1188
1189 static struct hashmap delta_base_cache;
1190 static size_t delta_base_cached;
1191
1192 static LIST_HEAD(delta_base_cache_lru);
1193
1194 struct delta_base_cache_key {
1195         struct packed_git *p;
1196         off_t base_offset;
1197 };
1198
1199 struct delta_base_cache_entry {
1200         struct hashmap hash;
1201         struct delta_base_cache_key key;
1202         struct list_head lru;
1203         void *data;
1204         unsigned long size;
1205         enum object_type type;
1206 };
1207
1208 static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1209 {
1210         unsigned int hash;
1211
1212         hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1213         hash += (hash >> 8) + (hash >> 16);
1214         return hash;
1215 }
1216
1217 static struct delta_base_cache_entry *
1218 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1219 {
1220         struct hashmap_entry entry;
1221         struct delta_base_cache_key key;
1222
1223         if (!delta_base_cache.cmpfn)
1224                 return NULL;
1225
1226         hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1227         key.p = p;
1228         key.base_offset = base_offset;
1229         return hashmap_get(&delta_base_cache, &entry, &key);
1230 }
1231
1232 static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1233                                    const struct delta_base_cache_key *b)
1234 {
1235         return a->p == b->p && a->base_offset == b->base_offset;
1236 }
1237
1238 static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1239                                      const void *va, const void *vb,
1240                                      const void *vkey)
1241 {
1242         const struct delta_base_cache_entry *a = va, *b = vb;
1243         const struct delta_base_cache_key *key = vkey;
1244         if (key)
1245                 return !delta_base_cache_key_eq(&a->key, key);
1246         else
1247                 return !delta_base_cache_key_eq(&a->key, &b->key);
1248 }
1249
1250 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1251 {
1252         return !!get_delta_base_cache_entry(p, base_offset);
1253 }
1254
1255 /*
1256  * Remove the entry from the cache, but do _not_ free the associated
1257  * entry data. The caller takes ownership of the "data" buffer, and
1258  * should copy out any fields it wants before detaching.
1259  */
1260 static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1261 {
1262         hashmap_remove(&delta_base_cache, ent, &ent->key);
1263         list_del(&ent->lru);
1264         delta_base_cached -= ent->size;
1265         free(ent);
1266 }
1267
1268 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1269         unsigned long *base_size, enum object_type *type)
1270 {
1271         struct delta_base_cache_entry *ent;
1272
1273         ent = get_delta_base_cache_entry(p, base_offset);
1274         if (!ent)
1275                 return unpack_entry(p, base_offset, type, base_size);
1276
1277         if (type)
1278                 *type = ent->type;
1279         if (base_size)
1280                 *base_size = ent->size;
1281         return xmemdupz(ent->data, ent->size);
1282 }
1283
1284 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1285 {
1286         free(ent->data);
1287         detach_delta_base_cache_entry(ent);
1288 }
1289
1290 void clear_delta_base_cache(void)
1291 {
1292         struct list_head *lru, *tmp;
1293         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1294                 struct delta_base_cache_entry *entry =
1295                         list_entry(lru, struct delta_base_cache_entry, lru);
1296                 release_delta_base_cache(entry);
1297         }
1298 }
1299
1300 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1301         void *base, unsigned long base_size, enum object_type type)
1302 {
1303         struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1304         struct list_head *lru, *tmp;
1305
1306         delta_base_cached += base_size;
1307
1308         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1309                 struct delta_base_cache_entry *f =
1310                         list_entry(lru, struct delta_base_cache_entry, lru);
1311                 if (delta_base_cached <= delta_base_cache_limit)
1312                         break;
1313                 release_delta_base_cache(f);
1314         }
1315
1316         ent->key.p = p;
1317         ent->key.base_offset = base_offset;
1318         ent->type = type;
1319         ent->data = base;
1320         ent->size = base_size;
1321         list_add_tail(&ent->lru, &delta_base_cache_lru);
1322
1323         if (!delta_base_cache.cmpfn)
1324                 hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1325         hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
1326         hashmap_add(&delta_base_cache, ent);
1327 }
1328
1329 int packed_object_info(struct packed_git *p, off_t obj_offset,
1330                        struct object_info *oi)
1331 {
1332         struct pack_window *w_curs = NULL;
1333         unsigned long size;
1334         off_t curpos = obj_offset;
1335         enum object_type type;
1336
1337         /*
1338          * We always get the representation type, but only convert it to
1339          * a "real" type later if the caller is interested.
1340          */
1341         if (oi->contentp) {
1342                 *oi->contentp = cache_or_unpack_entry(p, obj_offset, oi->sizep,
1343                                                       &type);
1344                 if (!*oi->contentp)
1345                         type = OBJ_BAD;
1346         } else {
1347                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1348         }
1349
1350         if (!oi->contentp && oi->sizep) {
1351                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1352                         off_t tmp_pos = curpos;
1353                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1354                                                            type, obj_offset);
1355                         if (!base_offset) {
1356                                 type = OBJ_BAD;
1357                                 goto out;
1358                         }
1359                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1360                         if (*oi->sizep == 0) {
1361                                 type = OBJ_BAD;
1362                                 goto out;
1363                         }
1364                 } else {
1365                         *oi->sizep = size;
1366                 }
1367         }
1368
1369         if (oi->disk_sizep) {
1370                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1371                 *oi->disk_sizep = revidx[1].offset - obj_offset;
1372         }
1373
1374         if (oi->typep || oi->typename) {
1375                 enum object_type ptot;
1376                 ptot = packed_to_object_type(p, obj_offset, type, &w_curs,
1377                                              curpos);
1378                 if (oi->typep)
1379                         *oi->typep = ptot;
1380                 if (oi->typename) {
1381                         const char *tn = typename(ptot);
1382                         if (tn)
1383                                 strbuf_addstr(oi->typename, tn);
1384                 }
1385                 if (ptot < 0) {
1386                         type = OBJ_BAD;
1387                         goto out;
1388                 }
1389         }
1390
1391         if (oi->delta_base_sha1) {
1392                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1393                         const unsigned char *base;
1394
1395                         base = get_delta_base_sha1(p, &w_curs, curpos,
1396                                                    type, obj_offset);
1397                         if (!base) {
1398                                 type = OBJ_BAD;
1399                                 goto out;
1400                         }
1401
1402                         hashcpy(oi->delta_base_sha1, base);
1403                 } else
1404                         hashclr(oi->delta_base_sha1);
1405         }
1406
1407         oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1408                                                           OI_PACKED;
1409
1410 out:
1411         unuse_pack(&w_curs);
1412         return type;
1413 }
1414
1415 static void *unpack_compressed_entry(struct packed_git *p,
1416                                     struct pack_window **w_curs,
1417                                     off_t curpos,
1418                                     unsigned long size)
1419 {
1420         int st;
1421         git_zstream stream;
1422         unsigned char *buffer, *in;
1423
1424         buffer = xmallocz_gently(size);
1425         if (!buffer)
1426                 return NULL;
1427         memset(&stream, 0, sizeof(stream));
1428         stream.next_out = buffer;
1429         stream.avail_out = size + 1;
1430
1431         git_inflate_init(&stream);
1432         do {
1433                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1434                 stream.next_in = in;
1435                 st = git_inflate(&stream, Z_FINISH);
1436                 if (!stream.avail_out)
1437                         break; /* the payload is larger than it should be */
1438                 curpos += stream.next_in - in;
1439         } while (st == Z_OK || st == Z_BUF_ERROR);
1440         git_inflate_end(&stream);
1441         if ((st != Z_STREAM_END) || stream.total_out != size) {
1442                 free(buffer);
1443                 return NULL;
1444         }
1445
1446         return buffer;
1447 }
1448
1449 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1450 {
1451         static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1452         trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1453                          p->pack_name, (uintmax_t)obj_offset);
1454 }
1455
1456 int do_check_packed_object_crc;
1457
1458 #define UNPACK_ENTRY_STACK_PREALLOC 64
1459 struct unpack_entry_stack_ent {
1460         off_t obj_offset;
1461         off_t curpos;
1462         unsigned long size;
1463 };
1464
1465 static void *read_object(const unsigned char *sha1, enum object_type *type,
1466                          unsigned long *size)
1467 {
1468         struct object_info oi = OBJECT_INFO_INIT;
1469         void *content;
1470         oi.typep = type;
1471         oi.sizep = size;
1472         oi.contentp = &content;
1473
1474         if (sha1_object_info_extended(sha1, &oi, 0) < 0)
1475                 return NULL;
1476         return content;
1477 }
1478
1479 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1480                    enum object_type *final_type, unsigned long *final_size)
1481 {
1482         struct pack_window *w_curs = NULL;
1483         off_t curpos = obj_offset;
1484         void *data = NULL;
1485         unsigned long size;
1486         enum object_type type;
1487         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1488         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1489         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1490         int base_from_cache = 0;
1491
1492         write_pack_access_log(p, obj_offset);
1493
1494         /* PHASE 1: drill down to the innermost base object */
1495         for (;;) {
1496                 off_t base_offset;
1497                 int i;
1498                 struct delta_base_cache_entry *ent;
1499
1500                 ent = get_delta_base_cache_entry(p, curpos);
1501                 if (ent) {
1502                         type = ent->type;
1503                         data = ent->data;
1504                         size = ent->size;
1505                         detach_delta_base_cache_entry(ent);
1506                         base_from_cache = 1;
1507                         break;
1508                 }
1509
1510                 if (do_check_packed_object_crc && p->index_version > 1) {
1511                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1512                         off_t len = revidx[1].offset - obj_offset;
1513                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1514                                 const unsigned char *sha1 =
1515                                         nth_packed_object_sha1(p, revidx->nr);
1516                                 error("bad packed object CRC for %s",
1517                                       sha1_to_hex(sha1));
1518                                 mark_bad_packed_object(p, sha1);
1519                                 data = NULL;
1520                                 goto out;
1521                         }
1522                 }
1523
1524                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1525                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1526                         break;
1527
1528                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1529                 if (!base_offset) {
1530                         error("failed to validate delta base reference "
1531                               "at offset %"PRIuMAX" from %s",
1532                               (uintmax_t)curpos, p->pack_name);
1533                         /* bail to phase 2, in hopes of recovery */
1534                         data = NULL;
1535                         break;
1536                 }
1537
1538                 /* push object, proceed to base */
1539                 if (delta_stack_nr >= delta_stack_alloc
1540                     && delta_stack == small_delta_stack) {
1541                         delta_stack_alloc = alloc_nr(delta_stack_nr);
1542                         ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1543                         memcpy(delta_stack, small_delta_stack,
1544                                sizeof(*delta_stack)*delta_stack_nr);
1545                 } else {
1546                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1547                 }
1548                 i = delta_stack_nr++;
1549                 delta_stack[i].obj_offset = obj_offset;
1550                 delta_stack[i].curpos = curpos;
1551                 delta_stack[i].size = size;
1552
1553                 curpos = obj_offset = base_offset;
1554         }
1555
1556         /* PHASE 2: handle the base */
1557         switch (type) {
1558         case OBJ_OFS_DELTA:
1559         case OBJ_REF_DELTA:
1560                 if (data)
1561                         die("BUG: unpack_entry: left loop at a valid delta");
1562                 break;
1563         case OBJ_COMMIT:
1564         case OBJ_TREE:
1565         case OBJ_BLOB:
1566         case OBJ_TAG:
1567                 if (!base_from_cache)
1568                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
1569                 break;
1570         default:
1571                 data = NULL;
1572                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1573                       type, (uintmax_t)obj_offset, p->pack_name);
1574         }
1575
1576         /* PHASE 3: apply deltas in order */
1577
1578         /* invariants:
1579          *   'data' holds the base data, or NULL if there was corruption
1580          */
1581         while (delta_stack_nr) {
1582                 void *delta_data;
1583                 void *base = data;
1584                 void *external_base = NULL;
1585                 unsigned long delta_size, base_size = size;
1586                 int i;
1587
1588                 data = NULL;
1589
1590                 if (base)
1591                         add_delta_base_cache(p, obj_offset, base, base_size, type);
1592
1593                 if (!base) {
1594                         /*
1595                          * We're probably in deep shit, but let's try to fetch
1596                          * the required base anyway from another pack or loose.
1597                          * This is costly but should happen only in the presence
1598                          * of a corrupted pack, and is better than failing outright.
1599                          */
1600                         struct revindex_entry *revidx;
1601                         const unsigned char *base_sha1;
1602                         revidx = find_pack_revindex(p, obj_offset);
1603                         if (revidx) {
1604                                 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1605                                 error("failed to read delta base object %s"
1606                                       " at offset %"PRIuMAX" from %s",
1607                                       sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
1608                                       p->pack_name);
1609                                 mark_bad_packed_object(p, base_sha1);
1610                                 base = read_object(base_sha1, &type, &base_size);
1611                                 external_base = base;
1612                         }
1613                 }
1614
1615                 i = --delta_stack_nr;
1616                 obj_offset = delta_stack[i].obj_offset;
1617                 curpos = delta_stack[i].curpos;
1618                 delta_size = delta_stack[i].size;
1619
1620                 if (!base)
1621                         continue;
1622
1623                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1624
1625                 if (!delta_data) {
1626                         error("failed to unpack compressed delta "
1627                               "at offset %"PRIuMAX" from %s",
1628                               (uintmax_t)curpos, p->pack_name);
1629                         data = NULL;
1630                         free(external_base);
1631                         continue;
1632                 }
1633
1634                 data = patch_delta(base, base_size,
1635                                    delta_data, delta_size,
1636                                    &size);
1637
1638                 /*
1639                  * We could not apply the delta; warn the user, but keep going.
1640                  * Our failure will be noticed either in the next iteration of
1641                  * the loop, or if this is the final delta, in the caller when
1642                  * we return NULL. Those code paths will take care of making
1643                  * a more explicit warning and retrying with another copy of
1644                  * the object.
1645                  */
1646                 if (!data)
1647                         error("failed to apply delta");
1648
1649                 free(delta_data);
1650                 free(external_base);
1651         }
1652
1653         if (final_type)
1654                 *final_type = type;
1655         if (final_size)
1656                 *final_size = size;
1657
1658 out:
1659         unuse_pack(&w_curs);
1660
1661         if (delta_stack != small_delta_stack)
1662                 free(delta_stack);
1663
1664         return data;
1665 }
1666
1667 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1668                                             uint32_t n)
1669 {
1670         const unsigned char *index = p->index_data;
1671         if (!index) {
1672                 if (open_pack_index(p))
1673                         return NULL;
1674                 index = p->index_data;
1675         }
1676         if (n >= p->num_objects)
1677                 return NULL;
1678         index += 4 * 256;
1679         if (p->index_version == 1) {
1680                 return index + 24 * n + 4;
1681         } else {
1682                 index += 8;
1683                 return index + 20 * n;
1684         }
1685 }
1686
1687 const struct object_id *nth_packed_object_oid(struct object_id *oid,
1688                                               struct packed_git *p,
1689                                               uint32_t n)
1690 {
1691         const unsigned char *hash = nth_packed_object_sha1(p, n);
1692         if (!hash)
1693                 return NULL;
1694         hashcpy(oid->hash, hash);
1695         return oid;
1696 }
1697
1698 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1699 {
1700         const unsigned char *ptr = vptr;
1701         const unsigned char *start = p->index_data;
1702         const unsigned char *end = start + p->index_size;
1703         if (ptr < start)
1704                 die(_("offset before start of pack index for %s (corrupt index?)"),
1705                     p->pack_name);
1706         /* No need to check for underflow; .idx files must be at least 8 bytes */
1707         if (ptr >= end - 8)
1708                 die(_("offset beyond end of pack index for %s (truncated index?)"),
1709                     p->pack_name);
1710 }
1711
1712 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1713 {
1714         const unsigned char *index = p->index_data;
1715         index += 4 * 256;
1716         if (p->index_version == 1) {
1717                 return ntohl(*((uint32_t *)(index + 24 * n)));
1718         } else {
1719                 uint32_t off;
1720                 index += 8 + p->num_objects * (20 + 4);
1721                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1722                 if (!(off & 0x80000000))
1723                         return off;
1724                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1725                 check_pack_index_ptr(p, index);
1726                 return get_be64(index);
1727         }
1728 }
1729
1730 off_t find_pack_entry_one(const unsigned char *sha1,
1731                                   struct packed_git *p)
1732 {
1733         const uint32_t *level1_ofs = p->index_data;
1734         const unsigned char *index = p->index_data;
1735         unsigned hi, lo, stride;
1736         static int debug_lookup = -1;
1737
1738         if (debug_lookup < 0)
1739                 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1740
1741         if (!index) {
1742                 if (open_pack_index(p))
1743                         return 0;
1744                 level1_ofs = p->index_data;
1745                 index = p->index_data;
1746         }
1747         if (p->index_version > 1) {
1748                 level1_ofs += 2;
1749                 index += 8;
1750         }
1751         index += 4 * 256;
1752         hi = ntohl(level1_ofs[*sha1]);
1753         lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1754         if (p->index_version > 1) {
1755                 stride = 20;
1756         } else {
1757                 stride = 24;
1758                 index += 4;
1759         }
1760
1761         if (debug_lookup)
1762                 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1763                        sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1764
1765         while (lo < hi) {
1766                 unsigned mi = lo + (hi - lo) / 2;
1767                 int cmp = hashcmp(index + mi * stride, sha1);
1768
1769                 if (debug_lookup)
1770                         printf("lo %u hi %u rg %u mi %u\n",
1771                                lo, hi, hi - lo, mi);
1772                 if (!cmp)
1773                         return nth_packed_object_offset(p, mi);
1774                 if (cmp > 0)
1775                         hi = mi;
1776                 else
1777                         lo = mi+1;
1778         }
1779         return 0;
1780 }
1781
1782 int is_pack_valid(struct packed_git *p)
1783 {
1784         /* An already open pack is known to be valid. */
1785         if (p->pack_fd != -1)
1786                 return 1;
1787
1788         /* If the pack has one window completely covering the
1789          * file size, the pack is known to be valid even if
1790          * the descriptor is not currently open.
1791          */
1792         if (p->windows) {
1793                 struct pack_window *w = p->windows;
1794
1795                 if (!w->offset && w->len == p->pack_size)
1796                         return 1;
1797         }
1798
1799         /* Force the pack to open to prove its valid. */
1800         return !open_packed_git(p);
1801 }
1802
1803 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1804                                   struct packed_git *packs)
1805 {
1806         struct packed_git *p;
1807
1808         for (p = packs; p; p = p->next) {
1809                 if (find_pack_entry_one(sha1, p))
1810                         return p;
1811         }
1812         return NULL;
1813
1814 }
1815
1816 static int fill_pack_entry(const unsigned char *sha1,
1817                            struct pack_entry *e,
1818                            struct packed_git *p)
1819 {
1820         off_t offset;
1821
1822         if (p->num_bad_objects) {
1823                 unsigned i;
1824                 for (i = 0; i < p->num_bad_objects; i++)
1825                         if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1826                                 return 0;
1827         }
1828
1829         offset = find_pack_entry_one(sha1, p);
1830         if (!offset)
1831                 return 0;
1832
1833         /*
1834          * We are about to tell the caller where they can locate the
1835          * requested object.  We better make sure the packfile is
1836          * still here and can be accessed before supplying that
1837          * answer, as it may have been deleted since the index was
1838          * loaded!
1839          */
1840         if (!is_pack_valid(p))
1841                 return 0;
1842         e->offset = offset;
1843         e->p = p;
1844         hashcpy(e->sha1, sha1);
1845         return 1;
1846 }
1847
1848 int find_pack_entry_the_repository(const unsigned char *sha1, struct pack_entry *e)
1849 {
1850         struct list_head *pos;
1851
1852         prepare_packed_git(the_repository);
1853         if (!the_repository->objects->packed_git)
1854                 return 0;
1855
1856         list_for_each(pos, &the_repository->objects->packed_git_mru) {
1857                 struct packed_git *p = list_entry(pos, struct packed_git, mru);
1858                 if (fill_pack_entry(sha1, e, p)) {
1859                         list_move(&p->mru,
1860                                   &the_repository->objects->packed_git_mru);
1861                         return 1;
1862                 }
1863         }
1864         return 0;
1865 }
1866
1867 int has_sha1_pack(const unsigned char *sha1)
1868 {
1869         struct pack_entry e;
1870         return find_pack_entry(the_repository, sha1, &e);
1871 }
1872
1873 int has_pack_index(const unsigned char *sha1)
1874 {
1875         struct stat st;
1876         if (stat(sha1_pack_index_name(sha1), &st))
1877                 return 0;
1878         return 1;
1879 }
1880
1881 static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
1882 {
1883         uint32_t i;
1884         int r = 0;
1885
1886         for (i = 0; i < p->num_objects; i++) {
1887                 struct object_id oid;
1888
1889                 if (!nth_packed_object_oid(&oid, p, i))
1890                         return error("unable to get sha1 of object %u in %s",
1891                                      i, p->pack_name);
1892
1893                 r = cb(&oid, p, i, data);
1894                 if (r)
1895                         break;
1896         }
1897         return r;
1898 }
1899
1900 int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
1901 {
1902         struct packed_git *p;
1903         int r = 0;
1904         int pack_errors = 0;
1905
1906         prepare_packed_git(the_repository);
1907         for (p = the_repository->objects->packed_git; p; p = p->next) {
1908                 if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
1909                         continue;
1910                 if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
1911                     !p->pack_promisor)
1912                         continue;
1913                 if (open_pack_index(p)) {
1914                         pack_errors = 1;
1915                         continue;
1916                 }
1917                 r = for_each_object_in_pack(p, cb, data);
1918                 if (r)
1919                         break;
1920         }
1921         return r ? r : pack_errors;
1922 }
1923
1924 static int add_promisor_object(const struct object_id *oid,
1925                                struct packed_git *pack,
1926                                uint32_t pos,
1927                                void *set_)
1928 {
1929         struct oidset *set = set_;
1930         struct object *obj = parse_object(oid);
1931         if (!obj)
1932                 return 1;
1933
1934         oidset_insert(set, oid);
1935
1936         /*
1937          * If this is a tree, commit, or tag, the objects it refers
1938          * to are also promisor objects. (Blobs refer to no objects->)
1939          */
1940         if (obj->type == OBJ_TREE) {
1941                 struct tree *tree = (struct tree *)obj;
1942                 struct tree_desc desc;
1943                 struct name_entry entry;
1944                 if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
1945                         /*
1946                          * Error messages are given when packs are
1947                          * verified, so do not print any here.
1948                          */
1949                         return 0;
1950                 while (tree_entry_gently(&desc, &entry))
1951                         oidset_insert(set, entry.oid);
1952         } else if (obj->type == OBJ_COMMIT) {
1953                 struct commit *commit = (struct commit *) obj;
1954                 struct commit_list *parents = commit->parents;
1955
1956                 oidset_insert(set, &commit->tree->object.oid);
1957                 for (; parents; parents = parents->next)
1958                         oidset_insert(set, &parents->item->object.oid);
1959         } else if (obj->type == OBJ_TAG) {
1960                 struct tag *tag = (struct tag *) obj;
1961                 oidset_insert(set, &tag->tagged->oid);
1962         }
1963         return 0;
1964 }
1965
1966 int is_promisor_object(const struct object_id *oid)
1967 {
1968         static struct oidset promisor_objects;
1969         static int promisor_objects_prepared;
1970
1971         if (!promisor_objects_prepared) {
1972                 if (repository_format_partial_clone) {
1973                         for_each_packed_object(add_promisor_object,
1974                                                &promisor_objects,
1975                                                FOR_EACH_OBJECT_PROMISOR_ONLY);
1976                 }
1977                 promisor_objects_prepared = 1;
1978         }
1979         return oidset_contains(&promisor_objects, oid);
1980 }