Merge branch 'maint'
[git] / sha1_file.c
1 /*
2  * GIT - The information manager from hell
3  *
4  * Copyright (C) Linus Torvalds, 2005
5  *
6  * This handles basic git sha1 object files - packing, unpacking,
7  * creation etc.
8  */
9 #include "cache.h"
10 #include "delta.h"
11 #include "pack.h"
12 #include "blob.h"
13 #include "commit.h"
14 #include "tag.h"
15 #include "tree.h"
16
17 #ifndef O_NOATIME
18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
19 #define O_NOATIME 01000000
20 #else
21 #define O_NOATIME 0
22 #endif
23 #endif
24
25 #ifdef NO_C99_FORMAT
26 #define SZ_FMT "lu"
27 #else
28 #define SZ_FMT "zu"
29 #endif
30
31 const unsigned char null_sha1[20];
32
33 static unsigned int sha1_file_open_flag = O_NOATIME;
34
35 signed char hexval_table[256] = {
36          -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
37          -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
38          -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
39          -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
40          -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
41          -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
42           0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
43           8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
44          -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
45          -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
46          -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
47          -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
48          -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
49          -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
50          -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
51          -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
52          -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
53          -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
54          -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
55          -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
56          -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
57          -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
58          -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
59          -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
60          -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
61          -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
62          -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
63          -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
64          -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
65          -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
66          -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
67          -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
68 };
69
70 int get_sha1_hex(const char *hex, unsigned char *sha1)
71 {
72         int i;
73         for (i = 0; i < 20; i++) {
74                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
75                 if (val & ~0xff)
76                         return -1;
77                 *sha1++ = val;
78                 hex += 2;
79         }
80         return 0;
81 }
82
83 int safe_create_leading_directories(char *path)
84 {
85         char *pos = path;
86         struct stat st;
87
88         if (*pos == '/')
89                 pos++;
90
91         while (pos) {
92                 pos = strchr(pos, '/');
93                 if (!pos)
94                         break;
95                 *pos = 0;
96                 if (!stat(path, &st)) {
97                         /* path exists */
98                         if (!S_ISDIR(st.st_mode)) {
99                                 *pos = '/';
100                                 return -3;
101                         }
102                 }
103                 else if (mkdir(path, 0777)) {
104                         *pos = '/';
105                         return -1;
106                 }
107                 else if (adjust_shared_perm(path)) {
108                         *pos = '/';
109                         return -2;
110                 }
111                 *pos++ = '/';
112         }
113         return 0;
114 }
115
116 char * sha1_to_hex(const unsigned char *sha1)
117 {
118         static int bufno;
119         static char hexbuffer[4][50];
120         static const char hex[] = "0123456789abcdef";
121         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
122         int i;
123
124         for (i = 0; i < 20; i++) {
125                 unsigned int val = *sha1++;
126                 *buf++ = hex[val >> 4];
127                 *buf++ = hex[val & 0xf];
128         }
129         *buf = '\0';
130
131         return buffer;
132 }
133
134 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
135 {
136         int i;
137         for (i = 0; i < 20; i++) {
138                 static char hex[] = "0123456789abcdef";
139                 unsigned int val = sha1[i];
140                 char *pos = pathbuf + i*2 + (i > 0);
141                 *pos++ = hex[val >> 4];
142                 *pos = hex[val & 0xf];
143         }
144 }
145
146 /*
147  * NOTE! This returns a statically allocated buffer, so you have to be
148  * careful about using it. Do a "xstrdup()" if you need to save the
149  * filename.
150  *
151  * Also note that this returns the location for creating.  Reading
152  * SHA1 file can happen from any alternate directory listed in the
153  * DB_ENVIRONMENT environment variable if it is not found in
154  * the primary object database.
155  */
156 char *sha1_file_name(const unsigned char *sha1)
157 {
158         static char *name, *base;
159
160         if (!base) {
161                 const char *sha1_file_directory = get_object_directory();
162                 int len = strlen(sha1_file_directory);
163                 base = xmalloc(len + 60);
164                 memcpy(base, sha1_file_directory, len);
165                 memset(base+len, 0, 60);
166                 base[len] = '/';
167                 base[len+3] = '/';
168                 name = base + len + 1;
169         }
170         fill_sha1_path(name, sha1);
171         return base;
172 }
173
174 char *sha1_pack_name(const unsigned char *sha1)
175 {
176         static const char hex[] = "0123456789abcdef";
177         static char *name, *base, *buf;
178         int i;
179
180         if (!base) {
181                 const char *sha1_file_directory = get_object_directory();
182                 int len = strlen(sha1_file_directory);
183                 base = xmalloc(len + 60);
184                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
185                 name = base + len + 11;
186         }
187
188         buf = name;
189
190         for (i = 0; i < 20; i++) {
191                 unsigned int val = *sha1++;
192                 *buf++ = hex[val >> 4];
193                 *buf++ = hex[val & 0xf];
194         }
195         
196         return base;
197 }
198
199 char *sha1_pack_index_name(const unsigned char *sha1)
200 {
201         static const char hex[] = "0123456789abcdef";
202         static char *name, *base, *buf;
203         int i;
204
205         if (!base) {
206                 const char *sha1_file_directory = get_object_directory();
207                 int len = strlen(sha1_file_directory);
208                 base = xmalloc(len + 60);
209                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
210                 name = base + len + 11;
211         }
212
213         buf = name;
214
215         for (i = 0; i < 20; i++) {
216                 unsigned int val = *sha1++;
217                 *buf++ = hex[val >> 4];
218                 *buf++ = hex[val & 0xf];
219         }
220         
221         return base;
222 }
223
224 struct alternate_object_database *alt_odb_list;
225 static struct alternate_object_database **alt_odb_tail;
226
227 static void read_info_alternates(const char * alternates, int depth);
228
229 /*
230  * Prepare alternate object database registry.
231  *
232  * The variable alt_odb_list points at the list of struct
233  * alternate_object_database.  The elements on this list come from
234  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
235  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
236  * whose contents is similar to that environment variable but can be
237  * LF separated.  Its base points at a statically allocated buffer that
238  * contains "/the/directory/corresponding/to/.git/objects/...", while
239  * its name points just after the slash at the end of ".git/objects/"
240  * in the example above, and has enough space to hold 40-byte hex
241  * SHA1, an extra slash for the first level indirection, and the
242  * terminating NUL.
243  */
244 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
245 {
246         struct stat st;
247         const char *objdir = get_object_directory();
248         struct alternate_object_database *ent;
249         struct alternate_object_database *alt;
250         /* 43 = 40-byte + 2 '/' + terminating NUL */
251         int pfxlen = len;
252         int entlen = pfxlen + 43;
253         int base_len = -1;
254
255         if (*entry != '/' && relative_base) {
256                 /* Relative alt-odb */
257                 if (base_len < 0)
258                         base_len = strlen(relative_base) + 1;
259                 entlen += base_len;
260                 pfxlen += base_len;
261         }
262         ent = xmalloc(sizeof(*ent) + entlen);
263
264         if (*entry != '/' && relative_base) {
265                 memcpy(ent->base, relative_base, base_len - 1);
266                 ent->base[base_len - 1] = '/';
267                 memcpy(ent->base + base_len, entry, len);
268         }
269         else
270                 memcpy(ent->base, entry, pfxlen);
271
272         ent->name = ent->base + pfxlen + 1;
273         ent->base[pfxlen + 3] = '/';
274         ent->base[pfxlen] = ent->base[entlen-1] = 0;
275
276         /* Detect cases where alternate disappeared */
277         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
278                 error("object directory %s does not exist; "
279                       "check .git/objects/info/alternates.",
280                       ent->base);
281                 free(ent);
282                 return -1;
283         }
284
285         /* Prevent the common mistake of listing the same
286          * thing twice, or object directory itself.
287          */
288         for (alt = alt_odb_list; alt; alt = alt->next) {
289                 if (!memcmp(ent->base, alt->base, pfxlen)) {
290                         free(ent);
291                         return -1;
292                 }
293         }
294         if (!memcmp(ent->base, objdir, pfxlen)) {
295                 free(ent);
296                 return -1;
297         }
298
299         /* add the alternate entry */
300         *alt_odb_tail = ent;
301         alt_odb_tail = &(ent->next);
302         ent->next = NULL;
303
304         /* recursively add alternates */
305         read_info_alternates(ent->base, depth + 1);
306
307         ent->base[pfxlen] = '/';
308
309         return 0;
310 }
311
312 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
313                                  const char *relative_base, int depth)
314 {
315         const char *cp, *last;
316
317         if (depth > 5) {
318                 error("%s: ignoring alternate object stores, nesting too deep.",
319                                 relative_base);
320                 return;
321         }
322
323         last = alt;
324         while (last < ep) {
325                 cp = last;
326                 if (cp < ep && *cp == '#') {
327                         while (cp < ep && *cp != sep)
328                                 cp++;
329                         last = cp + 1;
330                         continue;
331                 }
332                 while (cp < ep && *cp != sep)
333                         cp++;
334                 if (last != cp) {
335                         if ((*last != '/') && depth) {
336                                 error("%s: ignoring relative alternate object store %s",
337                                                 relative_base, last);
338                         } else {
339                                 link_alt_odb_entry(last, cp - last,
340                                                 relative_base, depth);
341                         }
342                 }
343                 while (cp < ep && *cp == sep)
344                         cp++;
345                 last = cp;
346         }
347 }
348
349 static void read_info_alternates(const char * relative_base, int depth)
350 {
351         char *map;
352         struct stat st;
353         char path[PATH_MAX];
354         int fd;
355
356         sprintf(path, "%s/info/alternates", relative_base);
357         fd = open(path, O_RDONLY);
358         if (fd < 0)
359                 return;
360         if (fstat(fd, &st) || (st.st_size == 0)) {
361                 close(fd);
362                 return;
363         }
364         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
365         close(fd);
366
367         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
368
369         munmap(map, st.st_size);
370 }
371
372 void prepare_alt_odb(void)
373 {
374         const char *alt;
375
376         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
377         if (!alt) alt = "";
378
379         if (alt_odb_tail)
380                 return;
381         alt_odb_tail = &alt_odb_list;
382         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
383
384         read_info_alternates(get_object_directory(), 0);
385 }
386
387 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
388 {
389         char *name = sha1_file_name(sha1);
390         struct alternate_object_database *alt;
391
392         if (!stat(name, st))
393                 return name;
394         prepare_alt_odb();
395         for (alt = alt_odb_list; alt; alt = alt->next) {
396                 name = alt->name;
397                 fill_sha1_path(name, sha1);
398                 if (!stat(alt->base, st))
399                         return alt->base;
400         }
401         return NULL;
402 }
403
404 static unsigned int pack_used_ctr;
405 static unsigned int pack_mmap_calls;
406 static unsigned int peak_pack_open_windows;
407 static unsigned int pack_open_windows;
408 static size_t peak_pack_mapped;
409 static size_t pack_mapped;
410 struct packed_git *packed_git;
411
412 void pack_report()
413 {
414         fprintf(stderr,
415                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
416                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
417                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
418                 (size_t) getpagesize(),
419                 packed_git_window_size,
420                 packed_git_limit);
421         fprintf(stderr,
422                 "pack_report: pack_used_ctr            = %10u\n"
423                 "pack_report: pack_mmap_calls          = %10u\n"
424                 "pack_report: pack_open_windows        = %10u / %10u\n"
425                 "pack_report: pack_mapped              = "
426                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
427                 pack_used_ctr,
428                 pack_mmap_calls,
429                 pack_open_windows, peak_pack_open_windows,
430                 pack_mapped, peak_pack_mapped);
431 }
432
433 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
434                                 void **idx_map_)
435 {
436         void *idx_map;
437         uint32_t *index;
438         unsigned long idx_size;
439         int nr, i;
440         int fd = open(path, O_RDONLY);
441         struct stat st;
442         if (fd < 0)
443                 return -1;
444         if (fstat(fd, &st)) {
445                 close(fd);
446                 return -1;
447         }
448         idx_size = st.st_size;
449         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
450         close(fd);
451
452         index = idx_map;
453         *idx_map_ = idx_map;
454         *idx_size_ = idx_size;
455
456         /* check index map */
457         if (idx_size < 4*256 + 20 + 20)
458                 return error("index file %s is too small", path);
459
460         /* a future index format would start with this, as older git
461          * binaries would fail the non-monotonic index check below.
462          * give a nicer warning to the user if we can.
463          */
464         if (index[0] == htonl(PACK_IDX_SIGNATURE))
465                 return error("index file %s is a newer version"
466                         " and is not supported by this binary"
467                         " (try upgrading GIT to a newer version)",
468                         path);
469
470         nr = 0;
471         for (i = 0; i < 256; i++) {
472                 unsigned int n = ntohl(index[i]);
473                 if (n < nr)
474                         return error("non-monotonic index %s", path);
475                 nr = n;
476         }
477
478         /*
479          * Total size:
480          *  - 256 index entries 4 bytes each
481          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
482          *  - 20-byte SHA1 of the packfile
483          *  - 20-byte SHA1 file checksum
484          */
485         if (idx_size != 4*256 + nr * 24 + 20 + 20)
486                 return error("wrong index file size in %s", path);
487
488         return 0;
489 }
490
491 static void scan_windows(struct packed_git *p,
492         struct packed_git **lru_p,
493         struct pack_window **lru_w,
494         struct pack_window **lru_l)
495 {
496         struct pack_window *w, *w_l;
497
498         for (w_l = NULL, w = p->windows; w; w = w->next) {
499                 if (!w->inuse_cnt) {
500                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
501                                 *lru_p = p;
502                                 *lru_w = w;
503                                 *lru_l = w_l;
504                         }
505                 }
506                 w_l = w;
507         }
508 }
509
510 static int unuse_one_window(struct packed_git *current)
511 {
512         struct packed_git *p, *lru_p = NULL;
513         struct pack_window *lru_w = NULL, *lru_l = NULL;
514
515         if (current)
516                 scan_windows(current, &lru_p, &lru_w, &lru_l);
517         for (p = packed_git; p; p = p->next)
518                 scan_windows(p, &lru_p, &lru_w, &lru_l);
519         if (lru_p) {
520                 munmap(lru_w->base, lru_w->len);
521                 pack_mapped -= lru_w->len;
522                 if (lru_l)
523                         lru_l->next = lru_w->next;
524                 else {
525                         lru_p->windows = lru_w->next;
526                         if (!lru_p->windows && lru_p != current) {
527                                 close(lru_p->pack_fd);
528                                 lru_p->pack_fd = -1;
529                         }
530                 }
531                 free(lru_w);
532                 pack_open_windows--;
533                 return 1;
534         }
535         return 0;
536 }
537
538 void release_pack_memory(size_t need)
539 {
540         size_t cur = pack_mapped;
541         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
542                 ; /* nothing */
543 }
544
545 void unuse_pack(struct pack_window **w_cursor)
546 {
547         struct pack_window *w = *w_cursor;
548         if (w) {
549                 w->inuse_cnt--;
550                 *w_cursor = NULL;
551         }
552 }
553
554 /*
555  * Do not call this directly as this leaks p->pack_fd on error return;
556  * call open_packed_git() instead.
557  */
558 static int open_packed_git_1(struct packed_git *p)
559 {
560         struct stat st;
561         struct pack_header hdr;
562         unsigned char sha1[20];
563         unsigned char *idx_sha1;
564         long fd_flag;
565
566         p->pack_fd = open(p->pack_name, O_RDONLY);
567         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
568                 return -1;
569
570         /* If we created the struct before we had the pack we lack size. */
571         if (!p->pack_size) {
572                 if (!S_ISREG(st.st_mode))
573                         return error("packfile %s not a regular file", p->pack_name);
574                 p->pack_size = st.st_size;
575         } else if (p->pack_size != st.st_size)
576                 return error("packfile %s size changed", p->pack_name);
577
578         /* We leave these file descriptors open with sliding mmap;
579          * there is no point keeping them open across exec(), though.
580          */
581         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
582         if (fd_flag < 0)
583                 return error("cannot determine file descriptor flags");
584         fd_flag |= FD_CLOEXEC;
585         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
586                 return error("cannot set FD_CLOEXEC");
587
588         /* Verify we recognize this pack file format. */
589         if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
590                 return error("file %s is far too short to be a packfile", p->pack_name);
591         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
592                 return error("file %s is not a GIT packfile", p->pack_name);
593         if (!pack_version_ok(hdr.hdr_version))
594                 return error("packfile %s is version %u and not supported"
595                         " (try upgrading GIT to a newer version)",
596                         p->pack_name, ntohl(hdr.hdr_version));
597
598         /* Verify the pack matches its index. */
599         if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
600                 return error("packfile %s claims to have %u objects"
601                         " while index size indicates %u objects",
602                         p->pack_name, ntohl(hdr.hdr_entries),
603                         num_packed_objects(p));
604         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
605                 return error("end of packfile %s is unavailable", p->pack_name);
606         if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
607                 return error("packfile %s signature is unavailable", p->pack_name);
608         idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
609         if (hashcmp(sha1, idx_sha1))
610                 return error("packfile %s does not match index", p->pack_name);
611         return 0;
612 }
613
614 static int open_packed_git(struct packed_git *p)
615 {
616         if (!open_packed_git_1(p))
617                 return 0;
618         if (p->pack_fd != -1) {
619                 close(p->pack_fd);
620                 p->pack_fd = -1;
621         }
622         return -1;
623 }
624
625 static int in_window(struct pack_window *win, unsigned long offset)
626 {
627         /* We must promise at least 20 bytes (one hash) after the
628          * offset is available from this window, otherwise the offset
629          * is not actually in this window and a different window (which
630          * has that one hash excess) must be used.  This is to support
631          * the object header and delta base parsing routines below.
632          */
633         off_t win_off = win->offset;
634         return win_off <= offset
635                 && (offset + 20) <= (win_off + win->len);
636 }
637
638 unsigned char* use_pack(struct packed_git *p,
639                 struct pack_window **w_cursor,
640                 unsigned long offset,
641                 unsigned int *left)
642 {
643         struct pack_window *win = *w_cursor;
644
645         if (p->pack_fd == -1 && open_packed_git(p))
646                 die("packfile %s cannot be accessed", p->pack_name);
647
648         /* Since packfiles end in a hash of their content and its
649          * pointless to ask for an offset into the middle of that
650          * hash, and the in_window function above wouldn't match
651          * don't allow an offset too close to the end of the file.
652          */
653         if (offset > (p->pack_size - 20))
654                 die("offset beyond end of packfile (truncated pack?)");
655
656         if (!win || !in_window(win, offset)) {
657                 if (win)
658                         win->inuse_cnt--;
659                 for (win = p->windows; win; win = win->next) {
660                         if (in_window(win, offset))
661                                 break;
662                 }
663                 if (!win) {
664                         size_t window_align = packed_git_window_size / 2;
665                         win = xcalloc(1, sizeof(*win));
666                         win->offset = (offset / window_align) * window_align;
667                         win->len = p->pack_size - win->offset;
668                         if (win->len > packed_git_window_size)
669                                 win->len = packed_git_window_size;
670                         pack_mapped += win->len;
671                         while (packed_git_limit < pack_mapped
672                                 && unuse_one_window(p))
673                                 ; /* nothing */
674                         win->base = xmmap(NULL, win->len,
675                                 PROT_READ, MAP_PRIVATE,
676                                 p->pack_fd, win->offset);
677                         if (win->base == MAP_FAILED)
678                                 die("packfile %s cannot be mapped: %s",
679                                         p->pack_name,
680                                         strerror(errno));
681                         pack_mmap_calls++;
682                         pack_open_windows++;
683                         if (pack_mapped > peak_pack_mapped)
684                                 peak_pack_mapped = pack_mapped;
685                         if (pack_open_windows > peak_pack_open_windows)
686                                 peak_pack_open_windows = pack_open_windows;
687                         win->next = p->windows;
688                         p->windows = win;
689                 }
690         }
691         if (win != *w_cursor) {
692                 win->last_used = pack_used_ctr++;
693                 win->inuse_cnt++;
694                 *w_cursor = win;
695         }
696         offset -= win->offset;
697         if (left)
698                 *left = win->len - offset;
699         return win->base + offset;
700 }
701
702 struct packed_git *add_packed_git(char *path, int path_len, int local)
703 {
704         struct stat st;
705         struct packed_git *p;
706         unsigned long idx_size;
707         void *idx_map;
708         unsigned char sha1[20];
709
710         if (check_packed_git_idx(path, &idx_size, &idx_map))
711                 return NULL;
712
713         /* do we have a corresponding .pack file? */
714         strcpy(path + path_len - 4, ".pack");
715         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
716                 munmap(idx_map, idx_size);
717                 return NULL;
718         }
719         /* ok, it looks sane as far as we can check without
720          * actually mapping the pack file.
721          */
722         p = xmalloc(sizeof(*p) + path_len + 2);
723         strcpy(p->pack_name, path);
724         p->index_size = idx_size;
725         p->pack_size = st.st_size;
726         p->index_base = idx_map;
727         p->next = NULL;
728         p->windows = NULL;
729         p->pack_fd = -1;
730         p->pack_local = local;
731         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
732                 hashcpy(p->sha1, sha1);
733         return p;
734 }
735
736 struct packed_git *parse_pack_index(unsigned char *sha1)
737 {
738         char *path = sha1_pack_index_name(sha1);
739         return parse_pack_index_file(sha1, path);
740 }
741
742 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
743 {
744         struct packed_git *p;
745         unsigned long idx_size;
746         void *idx_map;
747         char *path;
748
749         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
750                 return NULL;
751
752         path = sha1_pack_name(sha1);
753
754         p = xmalloc(sizeof(*p) + strlen(path) + 2);
755         strcpy(p->pack_name, path);
756         p->index_size = idx_size;
757         p->pack_size = 0;
758         p->index_base = idx_map;
759         p->next = NULL;
760         p->windows = NULL;
761         p->pack_fd = -1;
762         hashcpy(p->sha1, sha1);
763         return p;
764 }
765
766 void install_packed_git(struct packed_git *pack)
767 {
768         pack->next = packed_git;
769         packed_git = pack;
770 }
771
772 static void prepare_packed_git_one(char *objdir, int local)
773 {
774         char path[PATH_MAX];
775         int len;
776         DIR *dir;
777         struct dirent *de;
778
779         sprintf(path, "%s/pack", objdir);
780         len = strlen(path);
781         dir = opendir(path);
782         if (!dir) {
783                 if (errno != ENOENT)
784                         error("unable to open object pack directory: %s: %s",
785                               path, strerror(errno));
786                 return;
787         }
788         path[len++] = '/';
789         while ((de = readdir(dir)) != NULL) {
790                 int namelen = strlen(de->d_name);
791                 struct packed_git *p;
792
793                 if (!has_extension(de->d_name, ".idx"))
794                         continue;
795
796                 /* Don't reopen a pack we already have. */
797                 strcpy(path + len, de->d_name);
798                 for (p = packed_git; p; p = p->next) {
799                         if (!memcmp(path, p->pack_name, len + namelen - 4))
800                                 break;
801                 }
802                 if (p)
803                         continue;
804                 /* See if it really is a valid .idx file with corresponding
805                  * .pack file that we can map.
806                  */
807                 p = add_packed_git(path, len + namelen, local);
808                 if (!p)
809                         continue;
810                 install_packed_git(p);
811         }
812         closedir(dir);
813 }
814
815 static int prepare_packed_git_run_once = 0;
816 void prepare_packed_git(void)
817 {
818         struct alternate_object_database *alt;
819
820         if (prepare_packed_git_run_once)
821                 return;
822         prepare_packed_git_one(get_object_directory(), 1);
823         prepare_alt_odb();
824         for (alt = alt_odb_list; alt; alt = alt->next) {
825                 alt->name[-1] = 0;
826                 prepare_packed_git_one(alt->base, 0);
827                 alt->name[-1] = '/';
828         }
829         prepare_packed_git_run_once = 1;
830 }
831
832 void reprepare_packed_git(void)
833 {
834         prepare_packed_git_run_once = 0;
835         prepare_packed_git();
836 }
837
838 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
839 {
840         unsigned char real_sha1[20];
841         hash_sha1_file(map, size, type, real_sha1);
842         return hashcmp(sha1, real_sha1) ? -1 : 0;
843 }
844
845 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
846 {
847         struct stat st;
848         void *map;
849         int fd;
850         char *filename = find_sha1_file(sha1, &st);
851
852         if (!filename) {
853                 return NULL;
854         }
855
856         fd = open(filename, O_RDONLY | sha1_file_open_flag);
857         if (fd < 0) {
858                 /* See if it works without O_NOATIME */
859                 switch (sha1_file_open_flag) {
860                 default:
861                         fd = open(filename, O_RDONLY);
862                         if (fd >= 0)
863                                 break;
864                 /* Fallthrough */
865                 case 0:
866                         return NULL;
867                 }
868
869                 /* If it failed once, it will probably fail again.
870                  * Stop using O_NOATIME
871                  */
872                 sha1_file_open_flag = 0;
873         }
874         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
875         close(fd);
876         *size = st.st_size;
877         return map;
878 }
879
880 int legacy_loose_object(unsigned char *map)
881 {
882         unsigned int word;
883
884         /*
885          * Is it a zlib-compressed buffer? If so, the first byte
886          * must be 0x78 (15-bit window size, deflated), and the
887          * first 16-bit word is evenly divisible by 31
888          */
889         word = (map[0] << 8) + map[1];
890         if (map[0] == 0x78 && !(word % 31))
891                 return 1;
892         else
893                 return 0;
894 }
895
896 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
897 {
898         unsigned shift;
899         unsigned char c;
900         unsigned long size;
901         unsigned long used = 0;
902
903         c = buf[used++];
904         *type = (c >> 4) & 7;
905         size = c & 15;
906         shift = 4;
907         while (c & 0x80) {
908                 if (len <= used)
909                         return 0;
910                 if (sizeof(long) * 8 <= shift)
911                         return 0;
912                 c = buf[used++];
913                 size += (c & 0x7f) << shift;
914                 shift += 7;
915         }
916         *sizep = size;
917         return used;
918 }
919
920 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
921 {
922         unsigned long size, used;
923         static const char valid_loose_object_type[8] = {
924                 0, /* OBJ_EXT */
925                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
926                 0, /* "delta" and others are invalid in a loose object */
927         };
928         enum object_type type;
929
930         /* Get the data stream */
931         memset(stream, 0, sizeof(*stream));
932         stream->next_in = map;
933         stream->avail_in = mapsize;
934         stream->next_out = buffer;
935         stream->avail_out = bufsiz;
936
937         if (legacy_loose_object(map)) {
938                 inflateInit(stream);
939                 return inflate(stream, 0);
940         }
941
942         used = unpack_object_header_gently(map, mapsize, &type, &size);
943         if (!used || !valid_loose_object_type[type])
944                 return -1;
945         map += used;
946         mapsize -= used;
947
948         /* Set up the stream for the rest.. */
949         stream->next_in = map;
950         stream->avail_in = mapsize;
951         inflateInit(stream);
952
953         /* And generate the fake traditional header */
954         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
955                                          type_names[type], size);
956         return 0;
957 }
958
959 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
960 {
961         int bytes = strlen(buffer) + 1;
962         unsigned char *buf = xmalloc(1+size);
963         unsigned long n;
964
965         n = stream->total_out - bytes;
966         if (n > size)
967                 n = size;
968         memcpy(buf, (char *) buffer + bytes, n);
969         bytes = n;
970         if (bytes < size) {
971                 stream->next_out = buf + bytes;
972                 stream->avail_out = size - bytes;
973                 while (inflate(stream, Z_FINISH) == Z_OK)
974                         /* nothing */;
975         }
976         buf[size] = 0;
977         inflateEnd(stream);
978         return buf;
979 }
980
981 /*
982  * We used to just use "sscanf()", but that's actually way
983  * too permissive for what we want to check. So do an anal
984  * object header parse by hand.
985  */
986 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
987 {
988         int i;
989         unsigned long size;
990
991         /*
992          * The type can be at most ten bytes (including the 
993          * terminating '\0' that we add), and is followed by
994          * a space. 
995          */
996         i = 10;
997         for (;;) {
998                 char c = *hdr++;
999                 if (c == ' ')
1000                         break;
1001                 if (!--i)
1002                         return -1;
1003                 *type++ = c;
1004         }
1005         *type = 0;
1006
1007         /*
1008          * The length must follow immediately, and be in canonical
1009          * decimal format (ie "010" is not valid).
1010          */
1011         size = *hdr++ - '0';
1012         if (size > 9)
1013                 return -1;
1014         if (size) {
1015                 for (;;) {
1016                         unsigned long c = *hdr - '0';
1017                         if (c > 9)
1018                                 break;
1019                         hdr++;
1020                         size = size * 10 + c;
1021                 }
1022         }
1023         *sizep = size;
1024
1025         /*
1026          * The length must be followed by a zero byte
1027          */
1028         return *hdr ? -1 : 0;
1029 }
1030
1031 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
1032 {
1033         int ret;
1034         z_stream stream;
1035         char hdr[8192];
1036
1037         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1038         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
1039                 return NULL;
1040
1041         return unpack_sha1_rest(&stream, hdr, *size);
1042 }
1043
1044 static unsigned long get_delta_base(struct packed_git *p,
1045                                     struct pack_window **w_curs,
1046                                     unsigned long offset,
1047                                     enum object_type kind,
1048                                     unsigned long delta_obj_offset,
1049                                     unsigned long *base_obj_offset)
1050 {
1051         unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
1052         unsigned long base_offset;
1053
1054         /* use_pack() assured us we have [base_info, base_info + 20)
1055          * as a range that we can look at without walking off the
1056          * end of the mapped window.  Its actually the hash size
1057          * that is assured.  An OFS_DELTA longer than the hash size
1058          * is stupid, as then a REF_DELTA would be smaller to store.
1059          */
1060         if (kind == OBJ_OFS_DELTA) {
1061                 unsigned used = 0;
1062                 unsigned char c = base_info[used++];
1063                 base_offset = c & 127;
1064                 while (c & 128) {
1065                         base_offset += 1;
1066                         if (!base_offset || base_offset & ~(~0UL >> 7))
1067                                 die("offset value overflow for delta base object");
1068                         c = base_info[used++];
1069                         base_offset = (base_offset << 7) + (c & 127);
1070                 }
1071                 base_offset = delta_obj_offset - base_offset;
1072                 if (base_offset >= delta_obj_offset)
1073                         die("delta base offset out of bound");
1074                 offset += used;
1075         } else if (kind == OBJ_REF_DELTA) {
1076                 /* The base entry _must_ be in the same pack */
1077                 base_offset = find_pack_entry_one(base_info, p);
1078                 if (!base_offset)
1079                         die("failed to find delta-pack base object %s",
1080                                 sha1_to_hex(base_info));
1081                 offset += 20;
1082         } else
1083                 die("I am totally screwed");
1084         *base_obj_offset = base_offset;
1085         return offset;
1086 }
1087
1088 /* forward declaration for a mutually recursive function */
1089 static int packed_object_info(struct packed_git *p, unsigned long offset,
1090                               char *type, unsigned long *sizep);
1091
1092 static int packed_delta_info(struct packed_git *p,
1093                              struct pack_window **w_curs,
1094                              unsigned long offset,
1095                              enum object_type kind,
1096                              unsigned long obj_offset,
1097                              char *type,
1098                              unsigned long *sizep)
1099 {
1100         unsigned long base_offset;
1101
1102         offset = get_delta_base(p, w_curs, offset, kind,
1103                 obj_offset, &base_offset);
1104
1105         /* We choose to only get the type of the base object and
1106          * ignore potentially corrupt pack file that expects the delta
1107          * based on a base with a wrong size.  This saves tons of
1108          * inflate() calls.
1109          */
1110         if (packed_object_info(p, base_offset, type, NULL))
1111                 die("cannot get info for delta-pack base");
1112
1113         if (sizep) {
1114                 const unsigned char *data;
1115                 unsigned char delta_head[20], *in;
1116                 unsigned long result_size;
1117                 z_stream stream;
1118                 int st;
1119
1120                 memset(&stream, 0, sizeof(stream));
1121                 stream.next_out = delta_head;
1122                 stream.avail_out = sizeof(delta_head);
1123
1124                 inflateInit(&stream);
1125                 do {
1126                         in = use_pack(p, w_curs, offset, &stream.avail_in);
1127                         stream.next_in = in;
1128                         st = inflate(&stream, Z_FINISH);
1129                         offset += stream.next_in - in;
1130                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1131                         && stream.total_out < sizeof(delta_head));
1132                 inflateEnd(&stream);
1133                 if ((st != Z_STREAM_END) &&
1134                     stream.total_out != sizeof(delta_head))
1135                         die("delta data unpack-initial failed");
1136
1137                 /* Examine the initial part of the delta to figure out
1138                  * the result size.
1139                  */
1140                 data = delta_head;
1141
1142                 /* ignore base size */
1143                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1144
1145                 /* Read the result size */
1146                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1147                 *sizep = result_size;
1148         }
1149         return 0;
1150 }
1151
1152 static unsigned long unpack_object_header(struct packed_git *p,
1153                 struct pack_window **w_curs,
1154                 unsigned long offset,
1155                 enum object_type *type,
1156                 unsigned long *sizep)
1157 {
1158         unsigned char *base;
1159         unsigned int left;
1160         unsigned long used;
1161
1162         /* use_pack() assures us we have [base, base + 20) available
1163          * as a range that we can look at at.  (Its actually the hash
1164          * size that is assured.)  With our object header encoding
1165          * the maximum deflated object size is 2^137, which is just
1166          * insane, so we know won't exceed what we have been given.
1167          */
1168         base = use_pack(p, w_curs, offset, &left);
1169         used = unpack_object_header_gently(base, left, type, sizep);
1170         if (!used)
1171                 die("object offset outside of pack file");
1172
1173         return offset + used;
1174 }
1175
1176 void packed_object_info_detail(struct packed_git *p,
1177                                unsigned long offset,
1178                                char *type,
1179                                unsigned long *size,
1180                                unsigned long *store_size,
1181                                unsigned int *delta_chain_length,
1182                                unsigned char *base_sha1)
1183 {
1184         struct pack_window *w_curs = NULL;
1185         unsigned long obj_offset, val;
1186         unsigned char *next_sha1;
1187         enum object_type kind;
1188
1189         *delta_chain_length = 0;
1190         obj_offset = offset;
1191         offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1192
1193         for (;;) {
1194                 switch (kind) {
1195                 default:
1196                         die("pack %s contains unknown object type %d",
1197                             p->pack_name, kind);
1198                 case OBJ_COMMIT:
1199                 case OBJ_TREE:
1200                 case OBJ_BLOB:
1201                 case OBJ_TAG:
1202                         strcpy(type, type_names[kind]);
1203                         *store_size = 0; /* notyet */
1204                         unuse_pack(&w_curs);
1205                         return;
1206                 case OBJ_OFS_DELTA:
1207                         get_delta_base(p, &w_curs, offset, kind,
1208                                 obj_offset, &offset);
1209                         if (*delta_chain_length == 0) {
1210                                 /* TODO: find base_sha1 as pointed by offset */
1211                         }
1212                         break;
1213                 case OBJ_REF_DELTA:
1214                         next_sha1 = use_pack(p, &w_curs, offset, NULL);
1215                         if (*delta_chain_length == 0)
1216                                 hashcpy(base_sha1, next_sha1);
1217                         offset = find_pack_entry_one(next_sha1, p);
1218                         break;
1219                 }
1220                 obj_offset = offset;
1221                 offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1222                 (*delta_chain_length)++;
1223         }
1224 }
1225
1226 static int packed_object_info(struct packed_git *p, unsigned long offset,
1227                               char *type, unsigned long *sizep)
1228 {
1229         struct pack_window *w_curs = NULL;
1230         unsigned long size, obj_offset = offset;
1231         enum object_type kind;
1232         int r;
1233
1234         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1235
1236         switch (kind) {
1237         case OBJ_OFS_DELTA:
1238         case OBJ_REF_DELTA:
1239                 r = packed_delta_info(p, &w_curs, offset, kind,
1240                         obj_offset, type, sizep);
1241                 unuse_pack(&w_curs);
1242                 return r;
1243         case OBJ_COMMIT:
1244         case OBJ_TREE:
1245         case OBJ_BLOB:
1246         case OBJ_TAG:
1247                 strcpy(type, type_names[kind]);
1248                 unuse_pack(&w_curs);
1249                 break;
1250         default:
1251                 die("pack %s contains unknown object type %d",
1252                     p->pack_name, kind);
1253         }
1254         if (sizep)
1255                 *sizep = size;
1256         return 0;
1257 }
1258
1259 static void *unpack_compressed_entry(struct packed_git *p,
1260                                     struct pack_window **w_curs,
1261                                     unsigned long offset,
1262                                     unsigned long size)
1263 {
1264         int st;
1265         z_stream stream;
1266         unsigned char *buffer, *in;
1267
1268         buffer = xmalloc(size + 1);
1269         buffer[size] = 0;
1270         memset(&stream, 0, sizeof(stream));
1271         stream.next_out = buffer;
1272         stream.avail_out = size;
1273
1274         inflateInit(&stream);
1275         do {
1276                 in = use_pack(p, w_curs, offset, &stream.avail_in);
1277                 stream.next_in = in;
1278                 st = inflate(&stream, Z_FINISH);
1279                 offset += stream.next_in - in;
1280         } while (st == Z_OK || st == Z_BUF_ERROR);
1281         inflateEnd(&stream);
1282         if ((st != Z_STREAM_END) || stream.total_out != size) {
1283                 free(buffer);
1284                 return NULL;
1285         }
1286
1287         return buffer;
1288 }
1289
1290 static void *unpack_delta_entry(struct packed_git *p,
1291                                 struct pack_window **w_curs,
1292                                 unsigned long offset,
1293                                 unsigned long delta_size,
1294                                 enum object_type kind,
1295                                 unsigned long obj_offset,
1296                                 char *type,
1297                                 unsigned long *sizep)
1298 {
1299         void *delta_data, *result, *base;
1300         unsigned long result_size, base_size, base_offset;
1301
1302         offset = get_delta_base(p, w_curs, offset, kind,
1303                 obj_offset, &base_offset);
1304         base = unpack_entry(p, base_offset, type, &base_size);
1305         if (!base)
1306                 die("failed to read delta base object at %lu from %s",
1307                     base_offset, p->pack_name);
1308
1309         delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1310         result = patch_delta(base, base_size,
1311                              delta_data, delta_size,
1312                              &result_size);
1313         if (!result)
1314                 die("failed to apply delta");
1315         free(delta_data);
1316         free(base);
1317         *sizep = result_size;
1318         return result;
1319 }
1320
1321 void *unpack_entry(struct packed_git *p, unsigned long offset,
1322                           char *type, unsigned long *sizep)
1323 {
1324         struct pack_window *w_curs = NULL;
1325         unsigned long size, obj_offset = offset;
1326         enum object_type kind;
1327         void *retval;
1328
1329         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1330         switch (kind) {
1331         case OBJ_OFS_DELTA:
1332         case OBJ_REF_DELTA:
1333                 retval = unpack_delta_entry(p, &w_curs, offset, size,
1334                         kind, obj_offset, type, sizep);
1335                 break;
1336         case OBJ_COMMIT:
1337         case OBJ_TREE:
1338         case OBJ_BLOB:
1339         case OBJ_TAG:
1340                 strcpy(type, type_names[kind]);
1341                 *sizep = size;
1342                 retval = unpack_compressed_entry(p, &w_curs, offset, size);
1343                 break;
1344         default:
1345                 die("unknown object type %i in %s", kind, p->pack_name);
1346         }
1347         unuse_pack(&w_curs);
1348         return retval;
1349 }
1350
1351 int num_packed_objects(const struct packed_git *p)
1352 {
1353         /* See check_packed_git_idx() */
1354         return (p->index_size - 20 - 20 - 4*256) / 24;
1355 }
1356
1357 int nth_packed_object_sha1(const struct packed_git *p, int n,
1358                            unsigned char* sha1)
1359 {
1360         void *index = p->index_base + 256;
1361         if (n < 0 || num_packed_objects(p) <= n)
1362                 return -1;
1363         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1364         return 0;
1365 }
1366
1367 unsigned long find_pack_entry_one(const unsigned char *sha1,
1368                                   struct packed_git *p)
1369 {
1370         uint32_t *level1_ofs = p->index_base;
1371         int hi = ntohl(level1_ofs[*sha1]);
1372         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1373         void *index = p->index_base + 256;
1374
1375         do {
1376                 int mi = (lo + hi) / 2;
1377                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1378                 if (!cmp)
1379                         return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
1380                 if (cmp > 0)
1381                         hi = mi;
1382                 else
1383                         lo = mi+1;
1384         } while (lo < hi);
1385         return 0;
1386 }
1387
1388 static int matches_pack_name(struct packed_git *p, const char *ig)
1389 {
1390         const char *last_c, *c;
1391
1392         if (!strcmp(p->pack_name, ig))
1393                 return 0;
1394
1395         for (c = p->pack_name, last_c = c; *c;)
1396                 if (*c == '/')
1397                         last_c = ++c;
1398                 else
1399                         ++c;
1400         if (!strcmp(last_c, ig))
1401                 return 0;
1402
1403         return 1;
1404 }
1405
1406 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1407 {
1408         struct packed_git *p;
1409         unsigned long offset;
1410
1411         prepare_packed_git();
1412
1413         for (p = packed_git; p; p = p->next) {
1414                 if (ignore_packed) {
1415                         const char **ig;
1416                         for (ig = ignore_packed; *ig; ig++)
1417                                 if (!matches_pack_name(p, *ig))
1418                                         break;
1419                         if (*ig)
1420                                 continue;
1421                 }
1422                 offset = find_pack_entry_one(sha1, p);
1423                 if (offset) {
1424                         /*
1425                          * We are about to tell the caller where they can
1426                          * locate the requested object.  We better make
1427                          * sure the packfile is still here and can be
1428                          * accessed before supplying that answer, as
1429                          * it may have been deleted since the index
1430                          * was loaded!
1431                          */
1432                         if (p->pack_fd == -1 && open_packed_git(p)) {
1433                                 error("packfile %s cannot be accessed", p->pack_name);
1434                                 continue;
1435                         }
1436                         e->offset = offset;
1437                         e->p = p;
1438                         hashcpy(e->sha1, sha1);
1439                         return 1;
1440                 }
1441         }
1442         return 0;
1443 }
1444
1445 struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1446                                   struct packed_git *packs)
1447 {
1448         struct packed_git *p;
1449
1450         for (p = packs; p; p = p->next) {
1451                 if (find_pack_entry_one(sha1, p))
1452                         return p;
1453         }
1454         return NULL;
1455         
1456 }
1457
1458 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1459 {
1460         int status;
1461         unsigned long mapsize, size;
1462         void *map;
1463         z_stream stream;
1464         char hdr[128];
1465
1466         map = map_sha1_file(sha1, &mapsize);
1467         if (!map)
1468                 return error("unable to find %s", sha1_to_hex(sha1));
1469         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1470                 status = error("unable to unpack %s header",
1471                                sha1_to_hex(sha1));
1472         if (parse_sha1_header(hdr, type, &size) < 0)
1473                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1474         else {
1475                 status = 0;
1476                 if (sizep)
1477                         *sizep = size;
1478         }
1479         inflateEnd(&stream);
1480         munmap(map, mapsize);
1481         return status;
1482 }
1483
1484 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1485 {
1486         struct pack_entry e;
1487
1488         if (!find_pack_entry(sha1, &e, NULL)) {
1489                 reprepare_packed_git();
1490                 if (!find_pack_entry(sha1, &e, NULL))
1491                         return sha1_loose_object_info(sha1, type, sizep);
1492         }
1493         return packed_object_info(e.p, e.offset, type, sizep);
1494 }
1495
1496 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1497 {
1498         struct pack_entry e;
1499
1500         if (!find_pack_entry(sha1, &e, NULL))
1501                 return NULL;
1502         else
1503                 return unpack_entry(e.p, e.offset, type, size);
1504 }
1505
1506 /*
1507  * This is meant to hold a *small* number of objects that you would
1508  * want read_sha1_file() to be able to return, but yet you do not want
1509  * to write them into the object store (e.g. a browse-only
1510  * application).
1511  */
1512 static struct cached_object {
1513         unsigned char sha1[20];
1514         const char *type;
1515         void *buf;
1516         unsigned long size;
1517 } *cached_objects;
1518 static int cached_object_nr, cached_object_alloc;
1519
1520 static struct cached_object *find_cached_object(const unsigned char *sha1)
1521 {
1522         int i;
1523         struct cached_object *co = cached_objects;
1524
1525         for (i = 0; i < cached_object_nr; i++, co++) {
1526                 if (!hashcmp(co->sha1, sha1))
1527                         return co;
1528         }
1529         return NULL;
1530 }
1531
1532 int pretend_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *sha1)
1533 {
1534         struct cached_object *co;
1535
1536         hash_sha1_file(buf, len, type, sha1);
1537         if (has_sha1_file(sha1) || find_cached_object(sha1))
1538                 return 0;
1539         if (cached_object_alloc <= cached_object_nr) {
1540                 cached_object_alloc = alloc_nr(cached_object_alloc);
1541                 cached_objects = xrealloc(cached_objects,
1542                                           sizeof(*cached_objects) *
1543                                           cached_object_alloc);
1544         }
1545         co = &cached_objects[cached_object_nr++];
1546         co->size = len;
1547         co->type = strdup(type);
1548         co->buf = xmalloc(len);
1549         memcpy(co->buf, buf, len);
1550         hashcpy(co->sha1, sha1);
1551         return 0;
1552 }
1553
1554 void *read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1555 {
1556         unsigned long mapsize;
1557         void *map, *buf;
1558         struct cached_object *co;
1559
1560         co = find_cached_object(sha1);
1561         if (co) {
1562                 buf = xmalloc(co->size + 1);
1563                 memcpy(buf, co->buf, co->size);
1564                 ((char*)buf)[co->size] = 0;
1565                 strcpy(type, co->type);
1566                 *size = co->size;
1567                 return buf;
1568         }
1569
1570         buf = read_packed_sha1(sha1, type, size);
1571         if (buf)
1572                 return buf;
1573         map = map_sha1_file(sha1, &mapsize);
1574         if (map) {
1575                 buf = unpack_sha1_file(map, mapsize, type, size);
1576                 munmap(map, mapsize);
1577                 return buf;
1578         }
1579         reprepare_packed_git();
1580         return read_packed_sha1(sha1, type, size);
1581 }
1582
1583 void *read_object_with_reference(const unsigned char *sha1,
1584                                  const char *required_type,
1585                                  unsigned long *size,
1586                                  unsigned char *actual_sha1_return)
1587 {
1588         char type[20];
1589         void *buffer;
1590         unsigned long isize;
1591         unsigned char actual_sha1[20];
1592
1593         hashcpy(actual_sha1, sha1);
1594         while (1) {
1595                 int ref_length = -1;
1596                 const char *ref_type = NULL;
1597
1598                 buffer = read_sha1_file(actual_sha1, type, &isize);
1599                 if (!buffer)
1600                         return NULL;
1601                 if (!strcmp(type, required_type)) {
1602                         *size = isize;
1603                         if (actual_sha1_return)
1604                                 hashcpy(actual_sha1_return, actual_sha1);
1605                         return buffer;
1606                 }
1607                 /* Handle references */
1608                 else if (!strcmp(type, commit_type))
1609                         ref_type = "tree ";
1610                 else if (!strcmp(type, tag_type))
1611                         ref_type = "object ";
1612                 else {
1613                         free(buffer);
1614                         return NULL;
1615                 }
1616                 ref_length = strlen(ref_type);
1617
1618                 if (memcmp(buffer, ref_type, ref_length) ||
1619                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1620                         free(buffer);
1621                         return NULL;
1622                 }
1623                 free(buffer);
1624                 /* Now we have the ID of the referred-to object in
1625                  * actual_sha1.  Check again. */
1626         }
1627 }
1628
1629 static void write_sha1_file_prepare(void *buf, unsigned long len,
1630                                     const char *type, unsigned char *sha1,
1631                                     unsigned char *hdr, int *hdrlen)
1632 {
1633         SHA_CTX c;
1634
1635         /* Generate the header */
1636         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1637
1638         /* Sha1.. */
1639         SHA1_Init(&c);
1640         SHA1_Update(&c, hdr, *hdrlen);
1641         SHA1_Update(&c, buf, len);
1642         SHA1_Final(sha1, &c);
1643 }
1644
1645 /*
1646  * Link the tempfile to the final place, possibly creating the
1647  * last directory level as you do so.
1648  *
1649  * Returns the errno on failure, 0 on success.
1650  */
1651 static int link_temp_to_file(const char *tmpfile, const char *filename)
1652 {
1653         int ret;
1654         char *dir;
1655
1656         if (!link(tmpfile, filename))
1657                 return 0;
1658
1659         /*
1660          * Try to mkdir the last path component if that failed.
1661          *
1662          * Re-try the "link()" regardless of whether the mkdir
1663          * succeeds, since a race might mean that somebody
1664          * else succeeded.
1665          */
1666         ret = errno;
1667         dir = strrchr(filename, '/');
1668         if (dir) {
1669                 *dir = 0;
1670                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1671                         *dir = '/';
1672                         return -2;
1673                 }
1674                 *dir = '/';
1675                 if (!link(tmpfile, filename))
1676                         return 0;
1677                 ret = errno;
1678         }
1679         return ret;
1680 }
1681
1682 /*
1683  * Move the just written object into its final resting place
1684  */
1685 int move_temp_to_file(const char *tmpfile, const char *filename)
1686 {
1687         int ret = link_temp_to_file(tmpfile, filename);
1688
1689         /*
1690          * Coda hack - coda doesn't like cross-directory links,
1691          * so we fall back to a rename, which will mean that it
1692          * won't be able to check collisions, but that's not a
1693          * big deal.
1694          *
1695          * The same holds for FAT formatted media.
1696          *
1697          * When this succeeds, we just return 0. We have nothing
1698          * left to unlink.
1699          */
1700         if (ret && ret != EEXIST) {
1701                 if (!rename(tmpfile, filename))
1702                         return 0;
1703                 ret = errno;
1704         }
1705         unlink(tmpfile);
1706         if (ret) {
1707                 if (ret != EEXIST) {
1708                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1709                 }
1710                 /* FIXME!!! Collision check here ? */
1711         }
1712
1713         return 0;
1714 }
1715
1716 static int write_buffer(int fd, const void *buf, size_t len)
1717 {
1718         if (write_in_full(fd, buf, len) < 0)
1719                 return error("file write error (%s)", strerror(errno));
1720         return 0;
1721 }
1722
1723 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1724 {
1725         int hdr_len;
1726         unsigned char c;
1727
1728         c = (type << 4) | (len & 15);
1729         len >>= 4;
1730         hdr_len = 1;
1731         while (len) {
1732                 *hdr++ = c | 0x80;
1733                 hdr_len++;
1734                 c = (len & 0x7f);
1735                 len >>= 7;
1736         }
1737         *hdr = c;
1738         return hdr_len;
1739 }
1740
1741 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1742 {
1743         int obj_type, hdr;
1744
1745         if (use_legacy_headers) {
1746                 while (deflate(stream, 0) == Z_OK)
1747                         /* nothing */;
1748                 return;
1749         }
1750         if (!strcmp(type, blob_type))
1751                 obj_type = OBJ_BLOB;
1752         else if (!strcmp(type, tree_type))
1753                 obj_type = OBJ_TREE;
1754         else if (!strcmp(type, commit_type))
1755                 obj_type = OBJ_COMMIT;
1756         else if (!strcmp(type, tag_type))
1757                 obj_type = OBJ_TAG;
1758         else
1759                 die("trying to generate bogus object of type '%s'", type);
1760         hdr = write_binary_header(stream->next_out, obj_type, len);
1761         stream->total_out = hdr;
1762         stream->next_out += hdr;
1763         stream->avail_out -= hdr;
1764 }
1765
1766 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1767                    unsigned char *sha1)
1768 {
1769         unsigned char hdr[50];
1770         int hdrlen;
1771         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1772         return 0;
1773 }
1774
1775 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1776 {
1777         int size;
1778         unsigned char *compressed;
1779         z_stream stream;
1780         unsigned char sha1[20];
1781         char *filename;
1782         static char tmpfile[PATH_MAX];
1783         unsigned char hdr[50];
1784         int fd, hdrlen;
1785
1786         /* Normally if we have it in the pack then we do not bother writing
1787          * it out into .git/objects/??/?{38} file.
1788          */
1789         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1790         filename = sha1_file_name(sha1);
1791         if (returnsha1)
1792                 hashcpy(returnsha1, sha1);
1793         if (has_sha1_file(sha1))
1794                 return 0;
1795         fd = open(filename, O_RDONLY);
1796         if (fd >= 0) {
1797                 /*
1798                  * FIXME!!! We might do collision checking here, but we'd
1799                  * need to uncompress the old file and check it. Later.
1800                  */
1801                 close(fd);
1802                 return 0;
1803         }
1804
1805         if (errno != ENOENT) {
1806                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1807         }
1808
1809         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1810
1811         fd = mkstemp(tmpfile);
1812         if (fd < 0) {
1813                 if (errno == EPERM)
1814                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1815                 else
1816                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1817         }
1818
1819         /* Set it up */
1820         memset(&stream, 0, sizeof(stream));
1821         deflateInit(&stream, zlib_compression_level);
1822         size = 8 + deflateBound(&stream, len+hdrlen);
1823         compressed = xmalloc(size);
1824
1825         /* Compress it */
1826         stream.next_out = compressed;
1827         stream.avail_out = size;
1828
1829         /* First header.. */
1830         stream.next_in = hdr;
1831         stream.avail_in = hdrlen;
1832         setup_object_header(&stream, type, len);
1833
1834         /* Then the data itself.. */
1835         stream.next_in = buf;
1836         stream.avail_in = len;
1837         while (deflate(&stream, Z_FINISH) == Z_OK)
1838                 /* nothing */;
1839         deflateEnd(&stream);
1840         size = stream.total_out;
1841
1842         if (write_buffer(fd, compressed, size) < 0)
1843                 die("unable to write sha1 file");
1844         fchmod(fd, 0444);
1845         close(fd);
1846         free(compressed);
1847
1848         return move_temp_to_file(tmpfile, filename);
1849 }
1850
1851 /*
1852  * We need to unpack and recompress the object for writing
1853  * it out to a different file.
1854  */
1855 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1856 {
1857         size_t size;
1858         z_stream stream;
1859         unsigned char *unpacked;
1860         unsigned long len;
1861         char type[20];
1862         char hdr[50];
1863         int hdrlen;
1864         void *buf;
1865
1866         /* need to unpack and recompress it by itself */
1867         unpacked = read_packed_sha1(sha1, type, &len);
1868         if (!unpacked)
1869                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1870
1871         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1872
1873         /* Set it up */
1874         memset(&stream, 0, sizeof(stream));
1875         deflateInit(&stream, zlib_compression_level);
1876         size = deflateBound(&stream, len + hdrlen);
1877         buf = xmalloc(size);
1878
1879         /* Compress it */
1880         stream.next_out = buf;
1881         stream.avail_out = size;
1882
1883         /* First header.. */
1884         stream.next_in = (void *)hdr;
1885         stream.avail_in = hdrlen;
1886         while (deflate(&stream, 0) == Z_OK)
1887                 /* nothing */;
1888
1889         /* Then the data itself.. */
1890         stream.next_in = unpacked;
1891         stream.avail_in = len;
1892         while (deflate(&stream, Z_FINISH) == Z_OK)
1893                 /* nothing */;
1894         deflateEnd(&stream);
1895         free(unpacked);
1896
1897         *objsize = stream.total_out;
1898         return buf;
1899 }
1900
1901 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1902 {
1903         int retval;
1904         unsigned long objsize;
1905         void *buf = map_sha1_file(sha1, &objsize);
1906
1907         if (buf) {
1908                 retval = write_buffer(fd, buf, objsize);
1909                 munmap(buf, objsize);
1910                 return retval;
1911         }
1912
1913         buf = repack_object(sha1, &objsize);
1914         retval = write_buffer(fd, buf, objsize);
1915         free(buf);
1916         return retval;
1917 }
1918
1919 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1920                        size_t bufsize, size_t *bufposn)
1921 {
1922         char tmpfile[PATH_MAX];
1923         int local;
1924         z_stream stream;
1925         unsigned char real_sha1[20];
1926         unsigned char discard[4096];
1927         int ret;
1928         SHA_CTX c;
1929
1930         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1931
1932         local = mkstemp(tmpfile);
1933         if (local < 0) {
1934                 if (errno == EPERM)
1935                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1936                 else
1937                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1938         }
1939
1940         memset(&stream, 0, sizeof(stream));
1941
1942         inflateInit(&stream);
1943
1944         SHA1_Init(&c);
1945
1946         do {
1947                 ssize_t size;
1948                 if (*bufposn) {
1949                         stream.avail_in = *bufposn;
1950                         stream.next_in = (unsigned char *) buffer;
1951                         do {
1952                                 stream.next_out = discard;
1953                                 stream.avail_out = sizeof(discard);
1954                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1955                                 SHA1_Update(&c, discard, sizeof(discard) -
1956                                             stream.avail_out);
1957                         } while (stream.avail_in && ret == Z_OK);
1958                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1959                                 die("unable to write sha1 file");
1960                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1961                                 stream.avail_in);
1962                         *bufposn = stream.avail_in;
1963                         if (ret != Z_OK)
1964                                 break;
1965                 }
1966                 size = xread(fd, buffer + *bufposn, bufsize - *bufposn);
1967                 if (size <= 0) {
1968                         close(local);
1969                         unlink(tmpfile);
1970                         if (!size)
1971                                 return error("Connection closed?");
1972                         perror("Reading from connection");
1973                         return -1;
1974                 }
1975                 *bufposn += size;
1976         } while (1);
1977         inflateEnd(&stream);
1978
1979         close(local);
1980         SHA1_Final(real_sha1, &c);
1981         if (ret != Z_STREAM_END) {
1982                 unlink(tmpfile);
1983                 return error("File %s corrupted", sha1_to_hex(sha1));
1984         }
1985         if (hashcmp(sha1, real_sha1)) {
1986                 unlink(tmpfile);
1987                 return error("File %s has bad hash", sha1_to_hex(sha1));
1988         }
1989
1990         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1991 }
1992
1993 int has_pack_index(const unsigned char *sha1)
1994 {
1995         struct stat st;
1996         if (stat(sha1_pack_index_name(sha1), &st))
1997                 return 0;
1998         return 1;
1999 }
2000
2001 int has_pack_file(const unsigned char *sha1)
2002 {
2003         struct stat st;
2004         if (stat(sha1_pack_name(sha1), &st))
2005                 return 0;
2006         return 1;
2007 }
2008
2009 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
2010 {
2011         struct pack_entry e;
2012         return find_pack_entry(sha1, &e, ignore_packed);
2013 }
2014
2015 int has_sha1_file(const unsigned char *sha1)
2016 {
2017         struct stat st;
2018         struct pack_entry e;
2019
2020         if (find_pack_entry(sha1, &e, NULL))
2021                 return 1;
2022         return find_sha1_file(sha1, &st) ? 1 : 0;
2023 }
2024
2025 /*
2026  * reads from fd as long as possible into a supplied buffer of size bytes.
2027  * If necessary the buffer's size is increased using realloc()
2028  *
2029  * returns 0 if anything went fine and -1 otherwise
2030  *
2031  * NOTE: both buf and size may change, but even when -1 is returned
2032  * you still have to free() it yourself.
2033  */
2034 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
2035 {
2036         char* buf = *return_buf;
2037         unsigned long size = *return_size;
2038         int iret;
2039         unsigned long off = 0;
2040
2041         do {
2042                 iret = xread(fd, buf + off, size - off);
2043                 if (iret > 0) {
2044                         off += iret;
2045                         if (off == size) {
2046                                 size *= 2;
2047                                 buf = xrealloc(buf, size);
2048                         }
2049                 }
2050         } while (iret > 0);
2051
2052         *return_buf = buf;
2053         *return_size = off;
2054
2055         if (iret < 0)
2056                 return -1;
2057         return 0;
2058 }
2059
2060 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
2061 {
2062         unsigned long size = 4096;
2063         char *buf = xmalloc(size);
2064         int ret;
2065
2066         if (read_pipe(fd, &buf, &size)) {
2067                 free(buf);
2068                 return -1;
2069         }
2070
2071         if (!type)
2072                 type = blob_type;
2073         if (write_object)
2074                 ret = write_sha1_file(buf, size, type, sha1);
2075         else
2076                 ret = hash_sha1_file(buf, size, type, sha1);
2077         free(buf);
2078         return ret;
2079 }
2080
2081 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
2082 {
2083         unsigned long size = st->st_size;
2084         void *buf;
2085         int ret;
2086
2087         buf = "";
2088         if (size)
2089                 buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2090         close(fd);
2091
2092         if (!type)
2093                 type = blob_type;
2094         /* FIXME: CRLF -> LF conversion here for blobs! We'll need the path! */
2095         if (write_object)
2096                 ret = write_sha1_file(buf, size, type, sha1);
2097         else
2098                 ret = hash_sha1_file(buf, size, type, sha1);
2099         if (size)
2100                 munmap(buf, size);
2101         return ret;
2102 }
2103
2104 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2105 {
2106         int fd;
2107         char *target;
2108
2109         switch (st->st_mode & S_IFMT) {
2110         case S_IFREG:
2111                 fd = open(path, O_RDONLY);
2112                 if (fd < 0)
2113                         return error("open(\"%s\"): %s", path,
2114                                      strerror(errno));
2115                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
2116                         return error("%s: failed to insert into database",
2117                                      path);
2118                 break;
2119         case S_IFLNK:
2120                 target = xmalloc(st->st_size+1);
2121                 if (readlink(path, target, st->st_size+1) != st->st_size) {
2122                         char *errstr = strerror(errno);
2123                         free(target);
2124                         return error("readlink(\"%s\"): %s", path,
2125                                      errstr);
2126                 }
2127                 if (!write_object)
2128                         hash_sha1_file(target, st->st_size, blob_type, sha1);
2129                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
2130                         return error("%s: failed to insert into database",
2131                                      path);
2132                 free(target);
2133                 break;
2134         default:
2135                 return error("%s: unsupported file type", path);
2136         }
2137         return 0;
2138 }
2139
2140 int read_pack_header(int fd, struct pack_header *header)
2141 {
2142         char *c = (char*)header;
2143         ssize_t remaining = sizeof(struct pack_header);
2144         do {
2145                 ssize_t r = xread(fd, c, remaining);
2146                 if (r <= 0)
2147                         /* "eof before pack header was fully read" */
2148                         return PH_ERROR_EOF;
2149                 remaining -= r;
2150                 c += r;
2151         } while (remaining > 0);
2152         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2153                 /* "protocol error (pack signature mismatch detected)" */
2154                 return PH_ERROR_PACK_SIGNATURE;
2155         if (!pack_version_ok(header->hdr_version))
2156                 /* "protocol error (pack version unsupported)" */
2157                 return PH_ERROR_PROTOCOL;
2158         return 0;
2159 }