20562304b7035725b44b7b002b45e94838264827
[git/git.git] / packfile.c
1 #include "cache.h"
2 #include "mru.h"
3 #include "pack.h"
4 #include "dir.h"
5 #include "mergesort.h"
6 #include "packfile.h"
7 #include "delta.h"
8 #include "list.h"
9 #include "streaming.h"
10 #include "sha1-lookup.h"
11
12 char *odb_pack_name(struct strbuf *buf,
13 const unsigned char *sha1,
14 const char *ext)
15 {
16 strbuf_reset(buf);
17 strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
18 sha1_to_hex(sha1), ext);
19 return buf->buf;
20 }
21
22 char *sha1_pack_name(const unsigned char *sha1)
23 {
24 static struct strbuf buf = STRBUF_INIT;
25 return odb_pack_name(&buf, sha1, "pack");
26 }
27
28 char *sha1_pack_index_name(const unsigned char *sha1)
29 {
30 static struct strbuf buf = STRBUF_INIT;
31 return odb_pack_name(&buf, sha1, "idx");
32 }
33
34 static unsigned int pack_used_ctr;
35 static unsigned int pack_mmap_calls;
36 static unsigned int peak_pack_open_windows;
37 static unsigned int pack_open_windows;
38 static unsigned int pack_open_fds;
39 static unsigned int pack_max_fds;
40 static size_t peak_pack_mapped;
41 static size_t pack_mapped;
42 struct packed_git *packed_git;
43
44 static struct mru packed_git_mru_storage;
45 struct mru *packed_git_mru = &packed_git_mru_storage;
46
47 #define SZ_FMT PRIuMAX
48 static inline uintmax_t sz_fmt(size_t s) { return s; }
49
50 void pack_report(void)
51 {
52 fprintf(stderr,
53 "pack_report: getpagesize() = %10" SZ_FMT "\n"
54 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
55 "pack_report: core.packedGitLimit = %10" SZ_FMT "\n",
56 sz_fmt(getpagesize()),
57 sz_fmt(packed_git_window_size),
58 sz_fmt(packed_git_limit));
59 fprintf(stderr,
60 "pack_report: pack_used_ctr = %10u\n"
61 "pack_report: pack_mmap_calls = %10u\n"
62 "pack_report: pack_open_windows = %10u / %10u\n"
63 "pack_report: pack_mapped = "
64 "%10" SZ_FMT " / %10" SZ_FMT "\n",
65 pack_used_ctr,
66 pack_mmap_calls,
67 pack_open_windows, peak_pack_open_windows,
68 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
69 }
70
71 /*
72 * Open and mmap the index file at path, perform a couple of
73 * consistency checks, then record its information to p. Return 0 on
74 * success.
75 */
76 static int check_packed_git_idx(const char *path, struct packed_git *p)
77 {
78 void *idx_map;
79 struct pack_idx_header *hdr;
80 size_t idx_size;
81 uint32_t version, nr, i, *index;
82 int fd = git_open(path);
83 struct stat st;
84
85 if (fd < 0)
86 return -1;
87 if (fstat(fd, &st)) {
88 close(fd);
89 return -1;
90 }
91 idx_size = xsize_t(st.st_size);
92 if (idx_size < 4 * 256 + 20 + 20) {
93 close(fd);
94 return error("index file %s is too small", path);
95 }
96 idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
97 close(fd);
98
99 hdr = idx_map;
100 if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
101 version = ntohl(hdr->idx_version);
102 if (version < 2 || version > 2) {
103 munmap(idx_map, idx_size);
104 return error("index file %s is version %"PRIu32
105 " and is not supported by this binary"
106 " (try upgrading GIT to a newer version)",
107 path, version);
108 }
109 } else
110 version = 1;
111
112 nr = 0;
113 index = idx_map;
114 if (version > 1)
115 index += 2; /* skip index header */
116 for (i = 0; i < 256; i++) {
117 uint32_t n = ntohl(index[i]);
118 if (n < nr) {
119 munmap(idx_map, idx_size);
120 return error("non-monotonic index %s", path);
121 }
122 nr = n;
123 }
124
125 if (version == 1) {
126 /*
127 * Total size:
128 * - 256 index entries 4 bytes each
129 * - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
130 * - 20-byte SHA1 of the packfile
131 * - 20-byte SHA1 file checksum
132 */
133 if (idx_size != 4*256 + nr * 24 + 20 + 20) {
134 munmap(idx_map, idx_size);
135 return error("wrong index v1 file size in %s", path);
136 }
137 } else if (version == 2) {
138 /*
139 * Minimum size:
140 * - 8 bytes of header
141 * - 256 index entries 4 bytes each
142 * - 20-byte sha1 entry * nr
143 * - 4-byte crc entry * nr
144 * - 4-byte offset entry * nr
145 * - 20-byte SHA1 of the packfile
146 * - 20-byte SHA1 file checksum
147 * And after the 4-byte offset table might be a
148 * variable sized table containing 8-byte entries
149 * for offsets larger than 2^31.
150 */
151 unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
152 unsigned long max_size = min_size;
153 if (nr)
154 max_size += (nr - 1)*8;
155 if (idx_size < min_size || idx_size > max_size) {
156 munmap(idx_map, idx_size);
157 return error("wrong index v2 file size in %s", path);
158 }
159 if (idx_size != min_size &&
160 /*
161 * make sure we can deal with large pack offsets.
162 * 31-bit signed offset won't be enough, neither
163 * 32-bit unsigned one will be.
164 */
165 (sizeof(off_t) <= 4)) {
166 munmap(idx_map, idx_size);
167 return error("pack too large for current definition of off_t in %s", path);
168 }
169 }
170
171 p->index_version = version;
172 p->index_data = idx_map;
173 p->index_size = idx_size;
174 p->num_objects = nr;
175 return 0;
176 }
177
178 int open_pack_index(struct packed_git *p)
179 {
180 char *idx_name;
181 size_t len;
182 int ret;
183
184 if (p->index_data)
185 return 0;
186
187 if (!strip_suffix(p->pack_name, ".pack", &len))
188 die("BUG: pack_name does not end in .pack");
189 idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
190 ret = check_packed_git_idx(idx_name, p);
191 free(idx_name);
192 return ret;
193 }
194
195 static struct packed_git *alloc_packed_git(int extra)
196 {
197 struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
198 memset(p, 0, sizeof(*p));
199 p->pack_fd = -1;
200 return p;
201 }
202
203 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
204 {
205 const char *path = sha1_pack_name(sha1);
206 size_t alloc = st_add(strlen(path), 1);
207 struct packed_git *p = alloc_packed_git(alloc);
208
209 memcpy(p->pack_name, path, alloc); /* includes NUL */
210 hashcpy(p->sha1, sha1);
211 if (check_packed_git_idx(idx_path, p)) {
212 free(p);
213 return NULL;
214 }
215
216 return p;
217 }
218
219 static void scan_windows(struct packed_git *p,
220 struct packed_git **lru_p,
221 struct pack_window **lru_w,
222 struct pack_window **lru_l)
223 {
224 struct pack_window *w, *w_l;
225
226 for (w_l = NULL, w = p->windows; w; w = w->next) {
227 if (!w->inuse_cnt) {
228 if (!*lru_w || w->last_used < (*lru_w)->last_used) {
229 *lru_p = p;
230 *lru_w = w;
231 *lru_l = w_l;
232 }
233 }
234 w_l = w;
235 }
236 }
237
238 static int unuse_one_window(struct packed_git *current)
239 {
240 struct packed_git *p, *lru_p = NULL;
241 struct pack_window *lru_w = NULL, *lru_l = NULL;
242
243 if (current)
244 scan_windows(current, &lru_p, &lru_w, &lru_l);
245 for (p = packed_git; p; p = p->next)
246 scan_windows(p, &lru_p, &lru_w, &lru_l);
247 if (lru_p) {
248 munmap(lru_w->base, lru_w->len);
249 pack_mapped -= lru_w->len;
250 if (lru_l)
251 lru_l->next = lru_w->next;
252 else
253 lru_p->windows = lru_w->next;
254 free(lru_w);
255 pack_open_windows--;
256 return 1;
257 }
258 return 0;
259 }
260
261 void release_pack_memory(size_t need)
262 {
263 size_t cur = pack_mapped;
264 while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
265 ; /* nothing */
266 }
267
268 void close_pack_windows(struct packed_git *p)
269 {
270 while (p->windows) {
271 struct pack_window *w = p->windows;
272
273 if (w->inuse_cnt)
274 die("pack '%s' still has open windows to it",
275 p->pack_name);
276 munmap(w->base, w->len);
277 pack_mapped -= w->len;
278 pack_open_windows--;
279 p->windows = w->next;
280 free(w);
281 }
282 }
283
284 static int close_pack_fd(struct packed_git *p)
285 {
286 if (p->pack_fd < 0)
287 return 0;
288
289 close(p->pack_fd);
290 pack_open_fds--;
291 p->pack_fd = -1;
292
293 return 1;
294 }
295
296 void close_pack_index(struct packed_git *p)
297 {
298 if (p->index_data) {
299 munmap((void *)p->index_data, p->index_size);
300 p->index_data = NULL;
301 }
302 }
303
304 static void close_pack(struct packed_git *p)
305 {
306 close_pack_windows(p);
307 close_pack_fd(p);
308 close_pack_index(p);
309 }
310
311 void close_all_packs(void)
312 {
313 struct packed_git *p;
314
315 for (p = packed_git; p; p = p->next)
316 if (p->do_not_close)
317 die("BUG: want to close pack marked 'do-not-close'");
318 else
319 close_pack(p);
320 }
321
322 /*
323 * The LRU pack is the one with the oldest MRU window, preferring packs
324 * with no used windows, or the oldest mtime if it has no windows allocated.
325 */
326 static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
327 {
328 struct pack_window *w, *this_mru_w;
329 int has_windows_inuse = 0;
330
331 /*
332 * Reject this pack if it has windows and the previously selected
333 * one does not. If this pack does not have windows, reject
334 * it if the pack file is newer than the previously selected one.
335 */
336 if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
337 return;
338
339 for (w = this_mru_w = p->windows; w; w = w->next) {
340 /*
341 * Reject this pack if any of its windows are in use,
342 * but the previously selected pack did not have any
343 * inuse windows. Otherwise, record that this pack
344 * has windows in use.
345 */
346 if (w->inuse_cnt) {
347 if (*accept_windows_inuse)
348 has_windows_inuse = 1;
349 else
350 return;
351 }
352
353 if (w->last_used > this_mru_w->last_used)
354 this_mru_w = w;
355
356 /*
357 * Reject this pack if it has windows that have been
358 * used more recently than the previously selected pack.
359 * If the previously selected pack had windows inuse and
360 * we have not encountered a window in this pack that is
361 * inuse, skip this check since we prefer a pack with no
362 * inuse windows to one that has inuse windows.
363 */
364 if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
365 this_mru_w->last_used > (*mru_w)->last_used)
366 return;
367 }
368
369 /*
370 * Select this pack.
371 */
372 *mru_w = this_mru_w;
373 *lru_p = p;
374 *accept_windows_inuse = has_windows_inuse;
375 }
376
377 static int close_one_pack(void)
378 {
379 struct packed_git *p, *lru_p = NULL;
380 struct pack_window *mru_w = NULL;
381 int accept_windows_inuse = 1;
382
383 for (p = packed_git; p; p = p->next) {
384 if (p->pack_fd == -1)
385 continue;
386 find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
387 }
388
389 if (lru_p)
390 return close_pack_fd(lru_p);
391
392 return 0;
393 }
394
395 static unsigned int get_max_fd_limit(void)
396 {
397 #ifdef RLIMIT_NOFILE
398 {
399 struct rlimit lim;
400
401 if (!getrlimit(RLIMIT_NOFILE, &lim))
402 return lim.rlim_cur;
403 }
404 #endif
405
406 #ifdef _SC_OPEN_MAX
407 {
408 long open_max = sysconf(_SC_OPEN_MAX);
409 if (0 < open_max)
410 return open_max;
411 /*
412 * Otherwise, we got -1 for one of the two
413 * reasons:
414 *
415 * (1) sysconf() did not understand _SC_OPEN_MAX
416 * and signaled an error with -1; or
417 * (2) sysconf() said there is no limit.
418 *
419 * We _could_ clear errno before calling sysconf() to
420 * tell these two cases apart and return a huge number
421 * in the latter case to let the caller cap it to a
422 * value that is not so selfish, but letting the
423 * fallback OPEN_MAX codepath take care of these cases
424 * is a lot simpler.
425 */
426 }
427 #endif
428
429 #ifdef OPEN_MAX
430 return OPEN_MAX;
431 #else
432 return 1; /* see the caller ;-) */
433 #endif
434 }
435
436 /*
437 * Do not call this directly as this leaks p->pack_fd on error return;
438 * call open_packed_git() instead.
439 */
440 static int open_packed_git_1(struct packed_git *p)
441 {
442 struct stat st;
443 struct pack_header hdr;
444 unsigned char sha1[20];
445 unsigned char *idx_sha1;
446 long fd_flag;
447
448 if (!p->index_data && open_pack_index(p))
449 return error("packfile %s index unavailable", p->pack_name);
450
451 if (!pack_max_fds) {
452 unsigned int max_fds = get_max_fd_limit();
453
454 /* Save 3 for stdin/stdout/stderr, 22 for work */
455 if (25 < max_fds)
456 pack_max_fds = max_fds - 25;
457 else
458 pack_max_fds = 1;
459 }
460
461 while (pack_max_fds <= pack_open_fds && close_one_pack())
462 ; /* nothing */
463
464 p->pack_fd = git_open(p->pack_name);
465 if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
466 return -1;
467 pack_open_fds++;
468
469 /* If we created the struct before we had the pack we lack size. */
470 if (!p->pack_size) {
471 if (!S_ISREG(st.st_mode))
472 return error("packfile %s not a regular file", p->pack_name);
473 p->pack_size = st.st_size;
474 } else if (p->pack_size != st.st_size)
475 return error("packfile %s size changed", p->pack_name);
476
477 /* We leave these file descriptors open with sliding mmap;
478 * there is no point keeping them open across exec(), though.
479 */
480 fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
481 if (fd_flag < 0)
482 return error("cannot determine file descriptor flags");
483 fd_flag |= FD_CLOEXEC;
484 if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
485 return error("cannot set FD_CLOEXEC");
486
487 /* Verify we recognize this pack file format. */
488 if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
489 return error("file %s is far too short to be a packfile", p->pack_name);
490 if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
491 return error("file %s is not a GIT packfile", p->pack_name);
492 if (!pack_version_ok(hdr.hdr_version))
493 return error("packfile %s is version %"PRIu32" and not"
494 " supported (try upgrading GIT to a newer version)",
495 p->pack_name, ntohl(hdr.hdr_version));
496
497 /* Verify the pack matches its index. */
498 if (p->num_objects != ntohl(hdr.hdr_entries))
499 return error("packfile %s claims to have %"PRIu32" objects"
500 " while index indicates %"PRIu32" objects",
501 p->pack_name, ntohl(hdr.hdr_entries),
502 p->num_objects);
503 if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
504 return error("end of packfile %s is unavailable", p->pack_name);
505 if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
506 return error("packfile %s signature is unavailable", p->pack_name);
507 idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
508 if (hashcmp(sha1, idx_sha1))
509 return error("packfile %s does not match index", p->pack_name);
510 return 0;
511 }
512
513 static int open_packed_git(struct packed_git *p)
514 {
515 if (!open_packed_git_1(p))
516 return 0;
517 close_pack_fd(p);
518 return -1;
519 }
520
521 static int in_window(struct pack_window *win, off_t offset)
522 {
523 /* We must promise at least 20 bytes (one hash) after the
524 * offset is available from this window, otherwise the offset
525 * is not actually in this window and a different window (which
526 * has that one hash excess) must be used. This is to support
527 * the object header and delta base parsing routines below.
528 */
529 off_t win_off = win->offset;
530 return win_off <= offset
531 && (offset + 20) <= (win_off + win->len);
532 }
533
534 unsigned char *use_pack(struct packed_git *p,
535 struct pack_window **w_cursor,
536 off_t offset,
537 unsigned long *left)
538 {
539 struct pack_window *win = *w_cursor;
540
541 /* Since packfiles end in a hash of their content and it's
542 * pointless to ask for an offset into the middle of that
543 * hash, and the in_window function above wouldn't match
544 * don't allow an offset too close to the end of the file.
545 */
546 if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
547 die("packfile %s cannot be accessed", p->pack_name);
548 if (offset > (p->pack_size - 20))
549 die("offset beyond end of packfile (truncated pack?)");
550 if (offset < 0)
551 die(_("offset before end of packfile (broken .idx?)"));
552
553 if (!win || !in_window(win, offset)) {
554 if (win)
555 win->inuse_cnt--;
556 for (win = p->windows; win; win = win->next) {
557 if (in_window(win, offset))
558 break;
559 }
560 if (!win) {
561 size_t window_align = packed_git_window_size / 2;
562 off_t len;
563
564 if (p->pack_fd == -1 && open_packed_git(p))
565 die("packfile %s cannot be accessed", p->pack_name);
566
567 win = xcalloc(1, sizeof(*win));
568 win->offset = (offset / window_align) * window_align;
569 len = p->pack_size - win->offset;
570 if (len > packed_git_window_size)
571 len = packed_git_window_size;
572 win->len = (size_t)len;
573 pack_mapped += win->len;
574 while (packed_git_limit < pack_mapped
575 && unuse_one_window(p))
576 ; /* nothing */
577 win->base = xmmap(NULL, win->len,
578 PROT_READ, MAP_PRIVATE,
579 p->pack_fd, win->offset);
580 if (win->base == MAP_FAILED)
581 die_errno("packfile %s cannot be mapped",
582 p->pack_name);
583 if (!win->offset && win->len == p->pack_size
584 && !p->do_not_close)
585 close_pack_fd(p);
586 pack_mmap_calls++;
587 pack_open_windows++;
588 if (pack_mapped > peak_pack_mapped)
589 peak_pack_mapped = pack_mapped;
590 if (pack_open_windows > peak_pack_open_windows)
591 peak_pack_open_windows = pack_open_windows;
592 win->next = p->windows;
593 p->windows = win;
594 }
595 }
596 if (win != *w_cursor) {
597 win->last_used = pack_used_ctr++;
598 win->inuse_cnt++;
599 *w_cursor = win;
600 }
601 offset -= win->offset;
602 if (left)
603 *left = win->len - xsize_t(offset);
604 return win->base + offset;
605 }
606
607 void unuse_pack(struct pack_window **w_cursor)
608 {
609 struct pack_window *w = *w_cursor;
610 if (w) {
611 w->inuse_cnt--;
612 *w_cursor = NULL;
613 }
614 }
615
616 static void try_to_free_pack_memory(size_t size)
617 {
618 release_pack_memory(size);
619 }
620
621 struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
622 {
623 static int have_set_try_to_free_routine;
624 struct stat st;
625 size_t alloc;
626 struct packed_git *p;
627
628 if (!have_set_try_to_free_routine) {
629 have_set_try_to_free_routine = 1;
630 set_try_to_free_routine(try_to_free_pack_memory);
631 }
632
633 /*
634 * Make sure a corresponding .pack file exists and that
635 * the index looks sane.
636 */
637 if (!strip_suffix_mem(path, &path_len, ".idx"))
638 return NULL;
639
640 /*
641 * ".pack" is long enough to hold any suffix we're adding (and
642 * the use xsnprintf double-checks that)
643 */
644 alloc = st_add3(path_len, strlen(".pack"), 1);
645 p = alloc_packed_git(alloc);
646 memcpy(p->pack_name, path, path_len);
647
648 xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
649 if (!access(p->pack_name, F_OK))
650 p->pack_keep = 1;
651
652 xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
653 if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
654 free(p);
655 return NULL;
656 }
657
658 /* ok, it looks sane as far as we can check without
659 * actually mapping the pack file.
660 */
661 p->pack_size = st.st_size;
662 p->pack_local = local;
663 p->mtime = st.st_mtime;
664 if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
665 hashclr(p->sha1);
666 return p;
667 }
668
669 void install_packed_git(struct packed_git *pack)
670 {
671 if (pack->pack_fd != -1)
672 pack_open_fds++;
673
674 pack->next = packed_git;
675 packed_git = pack;
676 }
677
678 void (*report_garbage)(unsigned seen_bits, const char *path);
679
680 static void report_helper(const struct string_list *list,
681 int seen_bits, int first, int last)
682 {
683 if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
684 return;
685
686 for (; first < last; first++)
687 report_garbage(seen_bits, list->items[first].string);
688 }
689
690 static void report_pack_garbage(struct string_list *list)
691 {
692 int i, baselen = -1, first = 0, seen_bits = 0;
693
694 if (!report_garbage)
695 return;
696
697 string_list_sort(list);
698
699 for (i = 0; i < list->nr; i++) {
700 const char *path = list->items[i].string;
701 if (baselen != -1 &&
702 strncmp(path, list->items[first].string, baselen)) {
703 report_helper(list, seen_bits, first, i);
704 baselen = -1;
705 seen_bits = 0;
706 }
707 if (baselen == -1) {
708 const char *dot = strrchr(path, '.');
709 if (!dot) {
710 report_garbage(PACKDIR_FILE_GARBAGE, path);
711 continue;
712 }
713 baselen = dot - path + 1;
714 first = i;
715 }
716 if (!strcmp(path + baselen, "pack"))
717 seen_bits |= 1;
718 else if (!strcmp(path + baselen, "idx"))
719 seen_bits |= 2;
720 }
721 report_helper(list, seen_bits, first, list->nr);
722 }
723
724 static void prepare_packed_git_one(char *objdir, int local)
725 {
726 struct strbuf path = STRBUF_INIT;
727 size_t dirnamelen;
728 DIR *dir;
729 struct dirent *de;
730 struct string_list garbage = STRING_LIST_INIT_DUP;
731
732 strbuf_addstr(&path, objdir);
733 strbuf_addstr(&path, "/pack");
734 dir = opendir(path.buf);
735 if (!dir) {
736 if (errno != ENOENT)
737 error_errno("unable to open object pack directory: %s",
738 path.buf);
739 strbuf_release(&path);
740 return;
741 }
742 strbuf_addch(&path, '/');
743 dirnamelen = path.len;
744 while ((de = readdir(dir)) != NULL) {
745 struct packed_git *p;
746 size_t base_len;
747
748 if (is_dot_or_dotdot(de->d_name))
749 continue;
750
751 strbuf_setlen(&path, dirnamelen);
752 strbuf_addstr(&path, de->d_name);
753
754 base_len = path.len;
755 if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
756 /* Don't reopen a pack we already have. */
757 for (p = packed_git; p; p = p->next) {
758 size_t len;
759 if (strip_suffix(p->pack_name, ".pack", &len) &&
760 len == base_len &&
761 !memcmp(p->pack_name, path.buf, len))
762 break;
763 }
764 if (p == NULL &&
765 /*
766 * See if it really is a valid .idx file with
767 * corresponding .pack file that we can map.
768 */
769 (p = add_packed_git(path.buf, path.len, local)) != NULL)
770 install_packed_git(p);
771 }
772
773 if (!report_garbage)
774 continue;
775
776 if (ends_with(de->d_name, ".idx") ||
777 ends_with(de->d_name, ".pack") ||
778 ends_with(de->d_name, ".bitmap") ||
779 ends_with(de->d_name, ".keep"))
780 string_list_append(&garbage, path.buf);
781 else
782 report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
783 }
784 closedir(dir);
785 report_pack_garbage(&garbage);
786 string_list_clear(&garbage, 0);
787 strbuf_release(&path);
788 }
789
790 static int approximate_object_count_valid;
791
792 /*
793 * Give a fast, rough count of the number of objects in the repository. This
794 * ignores loose objects completely. If you have a lot of them, then either
795 * you should repack because your performance will be awful, or they are
796 * all unreachable objects about to be pruned, in which case they're not really
797 * interesting as a measure of repo size in the first place.
798 */
799 unsigned long approximate_object_count(void)
800 {
801 static unsigned long count;
802 if (!approximate_object_count_valid) {
803 struct packed_git *p;
804
805 prepare_packed_git();
806 count = 0;
807 for (p = packed_git; p; p = p->next) {
808 if (open_pack_index(p))
809 continue;
810 count += p->num_objects;
811 }
812 }
813 return count;
814 }
815
816 static void *get_next_packed_git(const void *p)
817 {
818 return ((const struct packed_git *)p)->next;
819 }
820
821 static void set_next_packed_git(void *p, void *next)
822 {
823 ((struct packed_git *)p)->next = next;
824 }
825
826 static int sort_pack(const void *a_, const void *b_)
827 {
828 const struct packed_git *a = a_;
829 const struct packed_git *b = b_;
830 int st;
831
832 /*
833 * Local packs tend to contain objects specific to our
834 * variant of the project than remote ones. In addition,
835 * remote ones could be on a network mounted filesystem.
836 * Favor local ones for these reasons.
837 */
838 st = a->pack_local - b->pack_local;
839 if (st)
840 return -st;
841
842 /*
843 * Younger packs tend to contain more recent objects,
844 * and more recent objects tend to get accessed more
845 * often.
846 */
847 if (a->mtime < b->mtime)
848 return 1;
849 else if (a->mtime == b->mtime)
850 return 0;
851 return -1;
852 }
853
854 static void rearrange_packed_git(void)
855 {
856 packed_git = llist_mergesort(packed_git, get_next_packed_git,
857 set_next_packed_git, sort_pack);
858 }
859
860 static void prepare_packed_git_mru(void)
861 {
862 struct packed_git *p;
863
864 mru_clear(packed_git_mru);
865 for (p = packed_git; p; p = p->next)
866 mru_append(packed_git_mru, p);
867 }
868
869 static int prepare_packed_git_run_once = 0;
870 void prepare_packed_git(void)
871 {
872 struct alternate_object_database *alt;
873
874 if (prepare_packed_git_run_once)
875 return;
876 prepare_packed_git_one(get_object_directory(), 1);
877 prepare_alt_odb();
878 for (alt = alt_odb_list; alt; alt = alt->next)
879 prepare_packed_git_one(alt->path, 0);
880 rearrange_packed_git();
881 prepare_packed_git_mru();
882 prepare_packed_git_run_once = 1;
883 }
884
885 void reprepare_packed_git(void)
886 {
887 approximate_object_count_valid = 0;
888 prepare_packed_git_run_once = 0;
889 prepare_packed_git();
890 }
891
892 unsigned long unpack_object_header_buffer(const unsigned char *buf,
893 unsigned long len, enum object_type *type, unsigned long *sizep)
894 {
895 unsigned shift;
896 unsigned long size, c;
897 unsigned long used = 0;
898
899 c = buf[used++];
900 *type = (c >> 4) & 7;
901 size = c & 15;
902 shift = 4;
903 while (c & 0x80) {
904 if (len <= used || bitsizeof(long) <= shift) {
905 error("bad object header");
906 size = used = 0;
907 break;
908 }
909 c = buf[used++];
910 size += (c & 0x7f) << shift;
911 shift += 7;
912 }
913 *sizep = size;
914 return used;
915 }
916
917 unsigned long get_size_from_delta(struct packed_git *p,
918 struct pack_window **w_curs,
919 off_t curpos)
920 {
921 const unsigned char *data;
922 unsigned char delta_head[20], *in;
923 git_zstream stream;
924 int st;
925
926 memset(&stream, 0, sizeof(stream));
927 stream.next_out = delta_head;
928 stream.avail_out = sizeof(delta_head);
929
930 git_inflate_init(&stream);
931 do {
932 in = use_pack(p, w_curs, curpos, &stream.avail_in);
933 stream.next_in = in;
934 st = git_inflate(&stream, Z_FINISH);
935 curpos += stream.next_in - in;
936 } while ((st == Z_OK || st == Z_BUF_ERROR) &&
937 stream.total_out < sizeof(delta_head));
938 git_inflate_end(&stream);
939 if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
940 error("delta data unpack-initial failed");
941 return 0;
942 }
943
944 /* Examine the initial part of the delta to figure out
945 * the result size.
946 */
947 data = delta_head;
948
949 /* ignore base size */
950 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
951
952 /* Read the result size */
953 return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
954 }
955
956 int unpack_object_header(struct packed_git *p,
957 struct pack_window **w_curs,
958 off_t *curpos,
959 unsigned long *sizep)
960 {
961 unsigned char *base;
962 unsigned long left;
963 unsigned long used;
964 enum object_type type;
965
966 /* use_pack() assures us we have [base, base + 20) available
967 * as a range that we can look at. (Its actually the hash
968 * size that is assured.) With our object header encoding
969 * the maximum deflated object size is 2^137, which is just
970 * insane, so we know won't exceed what we have been given.
971 */
972 base = use_pack(p, w_curs, *curpos, &left);
973 used = unpack_object_header_buffer(base, left, &type, sizep);
974 if (!used) {
975 type = OBJ_BAD;
976 } else
977 *curpos += used;
978
979 return type;
980 }
981
982 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
983 {
984 unsigned i;
985 for (i = 0; i < p->num_bad_objects; i++)
986 if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
987 return;
988 p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
989 st_mult(GIT_MAX_RAWSZ,
990 st_add(p->num_bad_objects, 1)));
991 hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
992 p->num_bad_objects++;
993 }
994
995 const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
996 {
997 struct packed_git *p;
998 unsigned i;
999
1000 for (p = packed_git; p; p = p->next)
1001 for (i = 0; i < p->num_bad_objects; i++)
1002 if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1003 return p;
1004 return NULL;
1005 }
1006
1007 static off_t get_delta_base(struct packed_git *p,
1008 struct pack_window **w_curs,
1009 off_t *curpos,
1010 enum object_type type,
1011 off_t delta_obj_offset)
1012 {
1013 unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1014 off_t base_offset;
1015
1016 /* use_pack() assured us we have [base_info, base_info + 20)
1017 * as a range that we can look at without walking off the
1018 * end of the mapped window. Its actually the hash size
1019 * that is assured. An OFS_DELTA longer than the hash size
1020 * is stupid, as then a REF_DELTA would be smaller to store.
1021 */
1022 if (type == OBJ_OFS_DELTA) {
1023 unsigned used = 0;
1024 unsigned char c = base_info[used++];
1025 base_offset = c & 127;
1026 while (c & 128) {
1027 base_offset += 1;
1028 if (!base_offset || MSB(base_offset, 7))
1029 return 0; /* overflow */
1030 c = base_info[used++];
1031 base_offset = (base_offset << 7) + (c & 127);
1032 }
1033 base_offset = delta_obj_offset - base_offset;
1034 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1035 return 0; /* out of bound */
1036 *curpos += used;
1037 } else if (type == OBJ_REF_DELTA) {
1038 /* The base entry _must_ be in the same pack */
1039 base_offset = find_pack_entry_one(base_info, p);
1040 *curpos += 20;
1041 } else
1042 die("I am totally screwed");
1043 return base_offset;
1044 }
1045
1046 /*
1047 * Like get_delta_base above, but we return the sha1 instead of the pack
1048 * offset. This means it is cheaper for REF deltas (we do not have to do
1049 * the final object lookup), but more expensive for OFS deltas (we
1050 * have to load the revidx to convert the offset back into a sha1).
1051 */
1052 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1053 struct pack_window **w_curs,
1054 off_t curpos,
1055 enum object_type type,
1056 off_t delta_obj_offset)
1057 {
1058 if (type == OBJ_REF_DELTA) {
1059 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1060 return base;
1061 } else if (type == OBJ_OFS_DELTA) {
1062 struct revindex_entry *revidx;
1063 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1064 type, delta_obj_offset);
1065
1066 if (!base_offset)
1067 return NULL;
1068
1069 revidx = find_pack_revindex(p, base_offset);
1070 if (!revidx)
1071 return NULL;
1072
1073 return nth_packed_object_sha1(p, revidx->nr);
1074 } else
1075 return NULL;
1076 }
1077
1078 static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1079 {
1080 int type;
1081 struct revindex_entry *revidx;
1082 const unsigned char *sha1;
1083 revidx = find_pack_revindex(p, obj_offset);
1084 if (!revidx)
1085 return OBJ_BAD;
1086 sha1 = nth_packed_object_sha1(p, revidx->nr);
1087 mark_bad_packed_object(p, sha1);
1088 type = sha1_object_info(sha1, NULL);
1089 if (type <= OBJ_NONE)
1090 return OBJ_BAD;
1091 return type;
1092 }
1093
1094 #define POI_STACK_PREALLOC 64
1095
1096 static enum object_type packed_to_object_type(struct packed_git *p,
1097 off_t obj_offset,
1098 enum object_type type,
1099 struct pack_window **w_curs,
1100 off_t curpos)
1101 {
1102 off_t small_poi_stack[POI_STACK_PREALLOC];
1103 off_t *poi_stack = small_poi_stack;
1104 int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1105
1106 while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1107 off_t base_offset;
1108 unsigned long size;
1109 /* Push the object we're going to leave behind */
1110 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1111 poi_stack_alloc = alloc_nr(poi_stack_nr);
1112 ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1113 memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1114 } else {
1115 ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1116 }
1117 poi_stack[poi_stack_nr++] = obj_offset;
1118 /* If parsing the base offset fails, just unwind */
1119 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1120 if (!base_offset)
1121 goto unwind;
1122 curpos = obj_offset = base_offset;
1123 type = unpack_object_header(p, w_curs, &curpos, &size);
1124 if (type <= OBJ_NONE) {
1125 /* If getting the base itself fails, we first
1126 * retry the base, otherwise unwind */
1127 type = retry_bad_packed_offset(p, base_offset);
1128 if (type > OBJ_NONE)
1129 goto out;
1130 goto unwind;
1131 }
1132 }
1133
1134 switch (type) {
1135 case OBJ_BAD:
1136 case OBJ_COMMIT:
1137 case OBJ_TREE:
1138 case OBJ_BLOB:
1139 case OBJ_TAG:
1140 break;
1141 default:
1142 error("unknown object type %i at offset %"PRIuMAX" in %s",
1143 type, (uintmax_t)obj_offset, p->pack_name);
1144 type = OBJ_BAD;
1145 }
1146
1147 out:
1148 if (poi_stack != small_poi_stack)
1149 free(poi_stack);
1150 return type;
1151
1152 unwind:
1153 while (poi_stack_nr) {
1154 obj_offset = poi_stack[--poi_stack_nr];
1155 type = retry_bad_packed_offset(p, obj_offset);
1156 if (type > OBJ_NONE)
1157 goto out;
1158 }
1159 type = OBJ_BAD;
1160 goto out;
1161 }
1162
1163 static struct hashmap delta_base_cache;
1164 static size_t delta_base_cached;
1165
1166 static LIST_HEAD(delta_base_cache_lru);
1167
1168 struct delta_base_cache_key {
1169 struct packed_git *p;
1170 off_t base_offset;
1171 };
1172
1173 struct delta_base_cache_entry {
1174 struct hashmap hash;
1175 struct delta_base_cache_key key;
1176 struct list_head lru;
1177 void *data;
1178 unsigned long size;
1179 enum object_type type;
1180 };
1181
1182 static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1183 {
1184 unsigned int hash;
1185
1186 hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1187 hash += (hash >> 8) + (hash >> 16);
1188 return hash;
1189 }
1190
1191 static struct delta_base_cache_entry *
1192 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1193 {
1194 struct hashmap_entry entry;
1195 struct delta_base_cache_key key;
1196
1197 if (!delta_base_cache.cmpfn)
1198 return NULL;
1199
1200 hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1201 key.p = p;
1202 key.base_offset = base_offset;
1203 return hashmap_get(&delta_base_cache, &entry, &key);
1204 }
1205
1206 static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1207 const struct delta_base_cache_key *b)
1208 {
1209 return a->p == b->p && a->base_offset == b->base_offset;
1210 }
1211
1212 static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1213 const void *va, const void *vb,
1214 const void *vkey)
1215 {
1216 const struct delta_base_cache_entry *a = va, *b = vb;
1217 const struct delta_base_cache_key *key = vkey;
1218 if (key)
1219 return !delta_base_cache_key_eq(&a->key, key);
1220 else
1221 return !delta_base_cache_key_eq(&a->key, &b->key);
1222 }
1223
1224 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1225 {
1226 return !!get_delta_base_cache_entry(p, base_offset);
1227 }
1228
1229 /*
1230 * Remove the entry from the cache, but do _not_ free the associated
1231 * entry data. The caller takes ownership of the "data" buffer, and
1232 * should copy out any fields it wants before detaching.
1233 */
1234 static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1235 {
1236 hashmap_remove(&delta_base_cache, ent, &ent->key);
1237 list_del(&ent->lru);
1238 delta_base_cached -= ent->size;
1239 free(ent);
1240 }
1241
1242 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1243 unsigned long *base_size, enum object_type *type)
1244 {
1245 struct delta_base_cache_entry *ent;
1246
1247 ent = get_delta_base_cache_entry(p, base_offset);
1248 if (!ent)
1249 return unpack_entry(p, base_offset, type, base_size);
1250
1251 if (type)
1252 *type = ent->type;
1253 if (base_size)
1254 *base_size = ent->size;
1255 return xmemdupz(ent->data, ent->size);
1256 }
1257
1258 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1259 {
1260 free(ent->data);
1261 detach_delta_base_cache_entry(ent);
1262 }
1263
1264 void clear_delta_base_cache(void)
1265 {
1266 struct list_head *lru, *tmp;
1267 list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1268 struct delta_base_cache_entry *entry =
1269 list_entry(lru, struct delta_base_cache_entry, lru);
1270 release_delta_base_cache(entry);
1271 }
1272 }
1273
1274 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1275 void *base, unsigned long base_size, enum object_type type)
1276 {
1277 struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1278 struct list_head *lru, *tmp;
1279
1280 delta_base_cached += base_size;
1281
1282 list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1283 struct delta_base_cache_entry *f =
1284 list_entry(lru, struct delta_base_cache_entry, lru);
1285 if (delta_base_cached <= delta_base_cache_limit)
1286 break;
1287 release_delta_base_cache(f);
1288 }
1289
1290 ent->key.p = p;
1291 ent->key.base_offset = base_offset;
1292 ent->type = type;
1293 ent->data = base;
1294 ent->size = base_size;
1295 list_add_tail(&ent->lru, &delta_base_cache_lru);
1296
1297 if (!delta_base_cache.cmpfn)
1298 hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1299 hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
1300 hashmap_add(&delta_base_cache, ent);
1301 }
1302
1303 int packed_object_info(struct packed_git *p, off_t obj_offset,
1304 struct object_info *oi)
1305 {
1306 struct pack_window *w_curs = NULL;
1307 unsigned long size;
1308 off_t curpos = obj_offset;
1309 enum object_type type;
1310
1311 /*
1312 * We always get the representation type, but only convert it to
1313 * a "real" type later if the caller is interested.
1314 */
1315 if (oi->contentp) {
1316 *oi->contentp = cache_or_unpack_entry(p, obj_offset, oi->sizep,
1317 &type);
1318 if (!*oi->contentp)
1319 type = OBJ_BAD;
1320 } else {
1321 type = unpack_object_header(p, &w_curs, &curpos, &size);
1322 }
1323
1324 if (!oi->contentp && oi->sizep) {
1325 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1326 off_t tmp_pos = curpos;
1327 off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1328 type, obj_offset);
1329 if (!base_offset) {
1330 type = OBJ_BAD;
1331 goto out;
1332 }
1333 *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1334 if (*oi->sizep == 0) {
1335 type = OBJ_BAD;
1336 goto out;
1337 }
1338 } else {
1339 *oi->sizep = size;
1340 }
1341 }
1342
1343 if (oi->disk_sizep) {
1344 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1345 *oi->disk_sizep = revidx[1].offset - obj_offset;
1346 }
1347
1348 if (oi->typep || oi->typename) {
1349 enum object_type ptot;
1350 ptot = packed_to_object_type(p, obj_offset, type, &w_curs,
1351 curpos);
1352 if (oi->typep)
1353 *oi->typep = ptot;
1354 if (oi->typename) {
1355 const char *tn = typename(ptot);
1356 if (tn)
1357 strbuf_addstr(oi->typename, tn);
1358 }
1359 if (ptot < 0) {
1360 type = OBJ_BAD;
1361 goto out;
1362 }
1363 }
1364
1365 if (oi->delta_base_sha1) {
1366 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1367 const unsigned char *base;
1368
1369 base = get_delta_base_sha1(p, &w_curs, curpos,
1370 type, obj_offset);
1371 if (!base) {
1372 type = OBJ_BAD;
1373 goto out;
1374 }
1375
1376 hashcpy(oi->delta_base_sha1, base);
1377 } else
1378 hashclr(oi->delta_base_sha1);
1379 }
1380
1381 oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1382 OI_PACKED;
1383
1384 out:
1385 unuse_pack(&w_curs);
1386 return type;
1387 }
1388
1389 static void *unpack_compressed_entry(struct packed_git *p,
1390 struct pack_window **w_curs,
1391 off_t curpos,
1392 unsigned long size)
1393 {
1394 int st;
1395 git_zstream stream;
1396 unsigned char *buffer, *in;
1397
1398 buffer = xmallocz_gently(size);
1399 if (!buffer)
1400 return NULL;
1401 memset(&stream, 0, sizeof(stream));
1402 stream.next_out = buffer;
1403 stream.avail_out = size + 1;
1404
1405 git_inflate_init(&stream);
1406 do {
1407 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1408 stream.next_in = in;
1409 st = git_inflate(&stream, Z_FINISH);
1410 if (!stream.avail_out)
1411 break; /* the payload is larger than it should be */
1412 curpos += stream.next_in - in;
1413 } while (st == Z_OK || st == Z_BUF_ERROR);
1414 git_inflate_end(&stream);
1415 if ((st != Z_STREAM_END) || stream.total_out != size) {
1416 free(buffer);
1417 return NULL;
1418 }
1419
1420 return buffer;
1421 }
1422
1423 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1424 {
1425 static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1426 trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1427 p->pack_name, (uintmax_t)obj_offset);
1428 }
1429
1430 int do_check_packed_object_crc;
1431
1432 #define UNPACK_ENTRY_STACK_PREALLOC 64
1433 struct unpack_entry_stack_ent {
1434 off_t obj_offset;
1435 off_t curpos;
1436 unsigned long size;
1437 };
1438
1439 static void *read_object(const unsigned char *sha1, enum object_type *type,
1440 unsigned long *size)
1441 {
1442 struct object_info oi = OBJECT_INFO_INIT;
1443 void *content;
1444 oi.typep = type;
1445 oi.sizep = size;
1446 oi.contentp = &content;
1447
1448 if (sha1_object_info_extended(sha1, &oi, 0) < 0)
1449 return NULL;
1450 return content;
1451 }
1452
1453 void *unpack_entry(struct packed_git *p, off_t obj_offset,
1454 enum object_type *final_type, unsigned long *final_size)
1455 {
1456 struct pack_window *w_curs = NULL;
1457 off_t curpos = obj_offset;
1458 void *data = NULL;
1459 unsigned long size;
1460 enum object_type type;
1461 struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1462 struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1463 int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1464 int base_from_cache = 0;
1465
1466 write_pack_access_log(p, obj_offset);
1467
1468 /* PHASE 1: drill down to the innermost base object */
1469 for (;;) {
1470 off_t base_offset;
1471 int i;
1472 struct delta_base_cache_entry *ent;
1473
1474 ent = get_delta_base_cache_entry(p, curpos);
1475 if (ent) {
1476 type = ent->type;
1477 data = ent->data;
1478 size = ent->size;
1479 detach_delta_base_cache_entry(ent);
1480 base_from_cache = 1;
1481 break;
1482 }
1483
1484 if (do_check_packed_object_crc && p->index_version > 1) {
1485 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1486 off_t len = revidx[1].offset - obj_offset;
1487 if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1488 const unsigned char *sha1 =
1489 nth_packed_object_sha1(p, revidx->nr);
1490 error("bad packed object CRC for %s",
1491 sha1_to_hex(sha1));
1492 mark_bad_packed_object(p, sha1);
1493 data = NULL;
1494 goto out;
1495 }
1496 }
1497
1498 type = unpack_object_header(p, &w_curs, &curpos, &size);
1499 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1500 break;
1501
1502 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1503 if (!base_offset) {
1504 error("failed to validate delta base reference "
1505 "at offset %"PRIuMAX" from %s",
1506 (uintmax_t)curpos, p->pack_name);
1507 /* bail to phase 2, in hopes of recovery */
1508 data = NULL;
1509 break;
1510 }
1511
1512 /* push object, proceed to base */
1513 if (delta_stack_nr >= delta_stack_alloc
1514 && delta_stack == small_delta_stack) {
1515 delta_stack_alloc = alloc_nr(delta_stack_nr);
1516 ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1517 memcpy(delta_stack, small_delta_stack,
1518 sizeof(*delta_stack)*delta_stack_nr);
1519 } else {
1520 ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1521 }
1522 i = delta_stack_nr++;
1523 delta_stack[i].obj_offset = obj_offset;
1524 delta_stack[i].curpos = curpos;
1525 delta_stack[i].size = size;
1526
1527 curpos = obj_offset = base_offset;
1528 }
1529
1530 /* PHASE 2: handle the base */
1531 switch (type) {
1532 case OBJ_OFS_DELTA:
1533 case OBJ_REF_DELTA:
1534 if (data)
1535 die("BUG: unpack_entry: left loop at a valid delta");
1536 break;
1537 case OBJ_COMMIT:
1538 case OBJ_TREE:
1539 case OBJ_BLOB:
1540 case OBJ_TAG:
1541 if (!base_from_cache)
1542 data = unpack_compressed_entry(p, &w_curs, curpos, size);
1543 break;
1544 default:
1545 data = NULL;
1546 error("unknown object type %i at offset %"PRIuMAX" in %s",
1547 type, (uintmax_t)obj_offset, p->pack_name);
1548 }
1549
1550 /* PHASE 3: apply deltas in order */
1551
1552 /* invariants:
1553 * 'data' holds the base data, or NULL if there was corruption
1554 */
1555 while (delta_stack_nr) {
1556 void *delta_data;
1557 void *base = data;
1558 void *external_base = NULL;
1559 unsigned long delta_size, base_size = size;
1560 int i;
1561
1562 data = NULL;
1563
1564 if (base)
1565 add_delta_base_cache(p, obj_offset, base, base_size, type);
1566
1567 if (!base) {
1568 /*
1569 * We're probably in deep shit, but let's try to fetch
1570 * the required base anyway from another pack or loose.
1571 * This is costly but should happen only in the presence
1572 * of a corrupted pack, and is better than failing outright.
1573 */
1574 struct revindex_entry *revidx;
1575 const unsigned char *base_sha1;
1576 revidx = find_pack_revindex(p, obj_offset);
1577 if (revidx) {
1578 base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1579 error("failed to read delta base object %s"
1580 " at offset %"PRIuMAX" from %s",
1581 sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
1582 p->pack_name);
1583 mark_bad_packed_object(p, base_sha1);
1584 base = read_object(base_sha1, &type, &base_size);
1585 external_base = base;
1586 }
1587 }
1588
1589 i = --delta_stack_nr;
1590 obj_offset = delta_stack[i].obj_offset;
1591 curpos = delta_stack[i].curpos;
1592 delta_size = delta_stack[i].size;
1593
1594 if (!base)
1595 continue;
1596
1597 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1598
1599 if (!delta_data) {
1600 error("failed to unpack compressed delta "
1601 "at offset %"PRIuMAX" from %s",
1602 (uintmax_t)curpos, p->pack_name);
1603 data = NULL;
1604 free(external_base);
1605 continue;
1606 }
1607
1608 data = patch_delta(base, base_size,
1609 delta_data, delta_size,
1610 &size);
1611
1612 /*
1613 * We could not apply the delta; warn the user, but keep going.
1614 * Our failure will be noticed either in the next iteration of
1615 * the loop, or if this is the final delta, in the caller when
1616 * we return NULL. Those code paths will take care of making
1617 * a more explicit warning and retrying with another copy of
1618 * the object.
1619 */
1620 if (!data)
1621 error("failed to apply delta");
1622
1623 free(delta_data);
1624 free(external_base);
1625 }
1626
1627 if (final_type)
1628 *final_type = type;
1629 if (final_size)
1630 *final_size = size;
1631
1632 out:
1633 unuse_pack(&w_curs);
1634
1635 if (delta_stack != small_delta_stack)
1636 free(delta_stack);
1637
1638 return data;
1639 }
1640
1641 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1642 uint32_t n)
1643 {
1644 const unsigned char *index = p->index_data;
1645 if (!index) {
1646 if (open_pack_index(p))
1647 return NULL;
1648 index = p->index_data;
1649 }
1650 if (n >= p->num_objects)
1651 return NULL;
1652 index += 4 * 256;
1653 if (p->index_version == 1) {
1654 return index + 24 * n + 4;
1655 } else {
1656 index += 8;
1657 return index + 20 * n;
1658 }
1659 }
1660
1661 const struct object_id *nth_packed_object_oid(struct object_id *oid,
1662 struct packed_git *p,
1663 uint32_t n)
1664 {
1665 const unsigned char *hash = nth_packed_object_sha1(p, n);
1666 if (!hash)
1667 return NULL;
1668 hashcpy(oid->hash, hash);
1669 return oid;
1670 }
1671
1672 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1673 {
1674 const unsigned char *ptr = vptr;
1675 const unsigned char *start = p->index_data;
1676 const unsigned char *end = start + p->index_size;
1677 if (ptr < start)
1678 die(_("offset before start of pack index for %s (corrupt index?)"),
1679 p->pack_name);
1680 /* No need to check for underflow; .idx files must be at least 8 bytes */
1681 if (ptr >= end - 8)
1682 die(_("offset beyond end of pack index for %s (truncated index?)"),
1683 p->pack_name);
1684 }
1685
1686 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1687 {
1688 const unsigned char *index = p->index_data;
1689 index += 4 * 256;
1690 if (p->index_version == 1) {
1691 return ntohl(*((uint32_t *)(index + 24 * n)));
1692 } else {
1693 uint32_t off;
1694 index += 8 + p->num_objects * (20 + 4);
1695 off = ntohl(*((uint32_t *)(index + 4 * n)));
1696 if (!(off & 0x80000000))
1697 return off;
1698 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1699 check_pack_index_ptr(p, index);
1700 return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1701 ntohl(*((uint32_t *)(index + 4)));
1702 }
1703 }
1704
1705 off_t find_pack_entry_one(const unsigned char *sha1,
1706 struct packed_git *p)
1707 {
1708 const uint32_t *level1_ofs = p->index_data;
1709 const unsigned char *index = p->index_data;
1710 unsigned hi, lo, stride;
1711 static int debug_lookup = -1;
1712
1713 if (debug_lookup < 0)
1714 debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1715
1716 if (!index) {
1717 if (open_pack_index(p))
1718 return 0;
1719 level1_ofs = p->index_data;
1720 index = p->index_data;
1721 }
1722 if (p->index_version > 1) {
1723 level1_ofs += 2;
1724 index += 8;
1725 }
1726 index += 4 * 256;
1727 hi = ntohl(level1_ofs[*sha1]);
1728 lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1729 if (p->index_version > 1) {
1730 stride = 20;
1731 } else {
1732 stride = 24;
1733 index += 4;
1734 }
1735
1736 if (debug_lookup)
1737 printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1738 sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1739
1740 while (lo < hi) {
1741 unsigned mi = (lo + hi) / 2;
1742 int cmp = hashcmp(index + mi * stride, sha1);
1743
1744 if (debug_lookup)
1745 printf("lo %u hi %u rg %u mi %u\n",
1746 lo, hi, hi - lo, mi);
1747 if (!cmp)
1748 return nth_packed_object_offset(p, mi);
1749 if (cmp > 0)
1750 hi = mi;
1751 else
1752 lo = mi+1;
1753 }
1754 return 0;
1755 }
1756
1757 int is_pack_valid(struct packed_git *p)
1758 {
1759 /* An already open pack is known to be valid. */
1760 if (p->pack_fd != -1)
1761 return 1;
1762
1763 /* If the pack has one window completely covering the
1764 * file size, the pack is known to be valid even if
1765 * the descriptor is not currently open.
1766 */
1767 if (p->windows) {
1768 struct pack_window *w = p->windows;
1769
1770 if (!w->offset && w->len == p->pack_size)
1771 return 1;
1772 }
1773
1774 /* Force the pack to open to prove its valid. */
1775 return !open_packed_git(p);
1776 }