Merge branch 'svn' of http://netz.smurf.noris.de/git/git
[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 <sys/types.h>
10 #include <dirent.h>
11 #include "cache.h"
12 #include "delta.h"
13 #include "pack.h"
14
15 #ifndef O_NOATIME
16 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
17 #define O_NOATIME 01000000
18 #else
19 #define O_NOATIME 0
20 #endif
21 #endif
22
23 const unsigned char null_sha1[20] = { 0, };
24
25 static unsigned int sha1_file_open_flag = O_NOATIME;
26
27 static unsigned hexval(char c)
28 {
29         if (c >= '0' && c <= '9')
30                 return c - '0';
31         if (c >= 'a' && c <= 'f')
32                 return c - 'a' + 10;
33         if (c >= 'A' && c <= 'F')
34                 return c - 'A' + 10;
35         return ~0;
36 }
37
38 int get_sha1_hex(const char *hex, unsigned char *sha1)
39 {
40         int i;
41         for (i = 0; i < 20; i++) {
42                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
43                 if (val & ~0xff)
44                         return -1;
45                 *sha1++ = val;
46                 hex += 2;
47         }
48         return 0;
49 }
50
51 int safe_create_leading_directories(char *path)
52 {
53         char *pos = path;
54
55         while (pos) {
56                 pos = strchr(pos, '/');
57                 if (!pos)
58                         break;
59                 *pos = 0;
60                 if (mkdir(path, 0777) < 0)
61                         if (errno != EEXIST) {
62                                 *pos = '/';
63                                 return -1;
64                         }
65                 *pos++ = '/';
66         }
67         return 0;
68 }
69
70 char * sha1_to_hex(const unsigned char *sha1)
71 {
72         static char buffer[50];
73         static const char hex[] = "0123456789abcdef";
74         char *buf = buffer;
75         int i;
76
77         for (i = 0; i < 20; i++) {
78                 unsigned int val = *sha1++;
79                 *buf++ = hex[val >> 4];
80                 *buf++ = hex[val & 0xf];
81         }
82         return buffer;
83 }
84
85 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
86 {
87         int i;
88         for (i = 0; i < 20; i++) {
89                 static char hex[] = "0123456789abcdef";
90                 unsigned int val = sha1[i];
91                 char *pos = pathbuf + i*2 + (i > 0);
92                 *pos++ = hex[val >> 4];
93                 *pos = hex[val & 0xf];
94         }
95 }
96
97 /*
98  * NOTE! This returns a statically allocated buffer, so you have to be
99  * careful about using it. Do a "strdup()" if you need to save the
100  * filename.
101  *
102  * Also note that this returns the location for creating.  Reading
103  * SHA1 file can happen from any alternate directory listed in the
104  * DB_ENVIRONMENT environment variable if it is not found in
105  * the primary object database.
106  */
107 char *sha1_file_name(const unsigned char *sha1)
108 {
109         static char *name, *base;
110
111         if (!base) {
112                 const char *sha1_file_directory = get_object_directory();
113                 int len = strlen(sha1_file_directory);
114                 base = xmalloc(len + 60);
115                 memcpy(base, sha1_file_directory, len);
116                 memset(base+len, 0, 60);
117                 base[len] = '/';
118                 base[len+3] = '/';
119                 name = base + len + 1;
120         }
121         fill_sha1_path(name, sha1);
122         return base;
123 }
124
125 char *sha1_pack_name(const unsigned char *sha1)
126 {
127         static const char hex[] = "0123456789abcdef";
128         static char *name, *base, *buf;
129         int i;
130
131         if (!base) {
132                 const char *sha1_file_directory = get_object_directory();
133                 int len = strlen(sha1_file_directory);
134                 base = xmalloc(len + 60);
135                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
136                 name = base + len + 11;
137         }
138
139         buf = name;
140
141         for (i = 0; i < 20; i++) {
142                 unsigned int val = *sha1++;
143                 *buf++ = hex[val >> 4];
144                 *buf++ = hex[val & 0xf];
145         }
146         
147         return base;
148 }
149
150 char *sha1_pack_index_name(const unsigned char *sha1)
151 {
152         static const char hex[] = "0123456789abcdef";
153         static char *name, *base, *buf;
154         int i;
155
156         if (!base) {
157                 const char *sha1_file_directory = get_object_directory();
158                 int len = strlen(sha1_file_directory);
159                 base = xmalloc(len + 60);
160                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
161                 name = base + len + 11;
162         }
163
164         buf = name;
165
166         for (i = 0; i < 20; i++) {
167                 unsigned int val = *sha1++;
168                 *buf++ = hex[val >> 4];
169                 *buf++ = hex[val & 0xf];
170         }
171         
172         return base;
173 }
174
175 struct alternate_object_database *alt_odb_list;
176 static struct alternate_object_database **alt_odb_tail;
177
178 /*
179  * Prepare alternate object database registry.
180  *
181  * The variable alt_odb_list points at the list of struct
182  * alternate_object_database.  The elements on this list come from
183  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
184  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
185  * whose contents is exactly in the same format as that environment
186  * variable.  Its base points at a statically allocated buffer that
187  * contains "/the/directory/corresponding/to/.git/objects/...", while
188  * its name points just after the slash at the end of ".git/objects/"
189  * in the example above, and has enough space to hold 40-byte hex
190  * SHA1, an extra slash for the first level indirection, and the
191  * terminating NUL.
192  */
193 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
194                                  const char *relative_base)
195 {
196         const char *cp, *last;
197         struct alternate_object_database *ent;
198         int base_len = -1;
199
200         last = alt;
201         while (last < ep) {
202                 cp = last;
203                 if (cp < ep && *cp == '#') {
204                         while (cp < ep && *cp != sep)
205                                 cp++;
206                         last = cp + 1;
207                         continue;
208                 }
209                 for ( ; cp < ep && *cp != sep; cp++)
210                         ;
211                 if (last != cp) {
212                         /* 43 = 40-byte + 2 '/' + terminating NUL */
213                         int pfxlen = cp - last;
214                         int entlen = pfxlen + 43;
215
216                         if (*last != '/' && relative_base) {
217                                 /* Relative alt-odb */
218                                 if (base_len < 0)
219                                         base_len = strlen(relative_base) + 1;
220                                 entlen += base_len;
221                                 pfxlen += base_len;
222                         }
223                         ent = xmalloc(sizeof(*ent) + entlen);
224                         *alt_odb_tail = ent;
225                         alt_odb_tail = &(ent->next);
226                         ent->next = NULL;
227                         if (*last != '/' && relative_base) {
228                                 memcpy(ent->base, relative_base, base_len - 1);
229                                 ent->base[base_len - 1] = '/';
230                                 memcpy(ent->base + base_len,
231                                        last, cp - last);
232                         }
233                         else
234                                 memcpy(ent->base, last, pfxlen);
235                         ent->name = ent->base + pfxlen + 1;
236                         ent->base[pfxlen] = ent->base[pfxlen + 3] = '/';
237                         ent->base[entlen-1] = 0;
238                 }
239                 while (cp < ep && *cp == sep)
240                         cp++;
241                 last = cp;
242         }
243 }
244
245 void prepare_alt_odb(void)
246 {
247         char path[PATH_MAX];
248         char *map;
249         int fd;
250         struct stat st;
251         char *alt;
252
253         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
254         if (!alt) alt = "";
255
256         if (alt_odb_tail)
257                 return;
258         alt_odb_tail = &alt_odb_list;
259         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL);
260
261         sprintf(path, "%s/info/alternates", get_object_directory());
262         fd = open(path, O_RDONLY);
263         if (fd < 0)
264                 return;
265         if (fstat(fd, &st) || (st.st_size == 0)) {
266                 close(fd);
267                 return;
268         }
269         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
270         close(fd);
271         if (map == MAP_FAILED)
272                 return;
273
274         link_alt_odb_entries(map, map + st.st_size, '\n',
275                              get_object_directory());
276         munmap(map, st.st_size);
277 }
278
279 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
280 {
281         char *name = sha1_file_name(sha1);
282         struct alternate_object_database *alt;
283
284         if (!stat(name, st))
285                 return name;
286         prepare_alt_odb();
287         for (alt = alt_odb_list; alt; alt = alt->next) {
288                 name = alt->name;
289                 fill_sha1_path(name, sha1);
290                 if (!stat(alt->base, st))
291                         return alt->base;
292         }
293         return NULL;
294 }
295
296 #define PACK_MAX_SZ (1<<26)
297 static int pack_used_ctr;
298 static unsigned long pack_mapped;
299 struct packed_git *packed_git;
300
301 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
302                                 void **idx_map_)
303 {
304         void *idx_map;
305         unsigned int *index;
306         unsigned long idx_size;
307         int nr, i;
308         int fd = open(path, O_RDONLY);
309         struct stat st;
310         if (fd < 0)
311                 return -1;
312         if (fstat(fd, &st)) {
313                 close(fd);
314                 return -1;
315         }
316         idx_size = st.st_size;
317         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
318         close(fd);
319         if (idx_map == MAP_FAILED)
320                 return -1;
321
322         index = idx_map;
323         *idx_map_ = idx_map;
324         *idx_size_ = idx_size;
325
326         /* check index map */
327         if (idx_size < 4*256 + 20 + 20)
328                 return error("index file too small");
329         nr = 0;
330         for (i = 0; i < 256; i++) {
331                 unsigned int n = ntohl(index[i]);
332                 if (n < nr)
333                         return error("non-monotonic index");
334                 nr = n;
335         }
336
337         /*
338          * Total size:
339          *  - 256 index entries 4 bytes each
340          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
341          *  - 20-byte SHA1 of the packfile
342          *  - 20-byte SHA1 file checksum
343          */
344         if (idx_size != 4*256 + nr * 24 + 20 + 20)
345                 return error("wrong index file size");
346
347         return 0;
348 }
349
350 static int unuse_one_packed_git(void)
351 {
352         struct packed_git *p, *lru = NULL;
353
354         for (p = packed_git; p; p = p->next) {
355                 if (p->pack_use_cnt || !p->pack_base)
356                         continue;
357                 if (!lru || p->pack_last_used < lru->pack_last_used)
358                         lru = p;
359         }
360         if (!lru)
361                 return 0;
362         munmap(lru->pack_base, lru->pack_size);
363         lru->pack_base = NULL;
364         return 1;
365 }
366
367 void unuse_packed_git(struct packed_git *p)
368 {
369         p->pack_use_cnt--;
370 }
371
372 int use_packed_git(struct packed_git *p)
373 {
374         if (!p->pack_size) {
375                 struct stat st;
376                 // We created the struct before we had the pack
377                 stat(p->pack_name, &st);
378                 if (!S_ISREG(st.st_mode))
379                         die("packfile %s not a regular file", p->pack_name);
380                 p->pack_size = st.st_size;
381         }
382         if (!p->pack_base) {
383                 int fd;
384                 struct stat st;
385                 void *map;
386
387                 pack_mapped += p->pack_size;
388                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
389                         ; /* nothing */
390                 fd = open(p->pack_name, O_RDONLY);
391                 if (fd < 0)
392                         die("packfile %s cannot be opened", p->pack_name);
393                 if (fstat(fd, &st)) {
394                         close(fd);
395                         die("packfile %s cannot be opened", p->pack_name);
396                 }
397                 if (st.st_size != p->pack_size)
398                         die("packfile %s size mismatch.", p->pack_name);
399                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
400                 close(fd);
401                 if (map == MAP_FAILED)
402                         die("packfile %s cannot be mapped.", p->pack_name);
403                 p->pack_base = map;
404
405                 /* Check if the pack file matches with the index file.
406                  * this is cheap.
407                  */
408                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
409                            p->pack_base + p->pack_size - 20, 20)) {
410                               
411                         die("packfile %s does not match index.", p->pack_name);
412                 }
413         }
414         p->pack_last_used = pack_used_ctr++;
415         p->pack_use_cnt++;
416         return 0;
417 }
418
419 struct packed_git *add_packed_git(char *path, int path_len, int local)
420 {
421         struct stat st;
422         struct packed_git *p;
423         unsigned long idx_size;
424         void *idx_map;
425
426         if (check_packed_git_idx(path, &idx_size, &idx_map))
427                 return NULL;
428
429         /* do we have a corresponding .pack file? */
430         strcpy(path + path_len - 4, ".pack");
431         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
432                 munmap(idx_map, idx_size);
433                 return NULL;
434         }
435         /* ok, it looks sane as far as we can check without
436          * actually mapping the pack file.
437          */
438         p = xmalloc(sizeof(*p) + path_len + 2);
439         strcpy(p->pack_name, path);
440         p->index_size = idx_size;
441         p->pack_size = st.st_size;
442         p->index_base = idx_map;
443         p->next = NULL;
444         p->pack_base = NULL;
445         p->pack_last_used = 0;
446         p->pack_use_cnt = 0;
447         p->pack_local = local;
448         return p;
449 }
450
451 struct packed_git *parse_pack_index(unsigned char *sha1)
452 {
453         char *path = sha1_pack_index_name(sha1);
454         return parse_pack_index_file(sha1, path);
455 }
456
457 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
458 {
459         struct packed_git *p;
460         unsigned long idx_size;
461         void *idx_map;
462         char *path;
463
464         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
465                 return NULL;
466
467         path = sha1_pack_name(sha1);
468
469         p = xmalloc(sizeof(*p) + strlen(path) + 2);
470         strcpy(p->pack_name, path);
471         p->index_size = idx_size;
472         p->pack_size = 0;
473         p->index_base = idx_map;
474         p->next = NULL;
475         p->pack_base = NULL;
476         p->pack_last_used = 0;
477         p->pack_use_cnt = 0;
478         memcpy(p->sha1, sha1, 20);
479         return p;
480 }
481
482 void install_packed_git(struct packed_git *pack)
483 {
484         pack->next = packed_git;
485         packed_git = pack;
486 }
487
488 static void prepare_packed_git_one(char *objdir, int local)
489 {
490         char path[PATH_MAX];
491         int len;
492         DIR *dir;
493         struct dirent *de;
494
495         sprintf(path, "%s/pack", objdir);
496         len = strlen(path);
497         dir = opendir(path);
498         if (!dir)
499                 return;
500         path[len++] = '/';
501         while ((de = readdir(dir)) != NULL) {
502                 int namelen = strlen(de->d_name);
503                 struct packed_git *p;
504
505                 if (strcmp(de->d_name + namelen - 4, ".idx"))
506                         continue;
507
508                 /* we have .idx.  Is it a file we can map? */
509                 strcpy(path + len, de->d_name);
510                 p = add_packed_git(path, len + namelen, local);
511                 if (!p)
512                         continue;
513                 p->next = packed_git;
514                 packed_git = p;
515         }
516         closedir(dir);
517 }
518
519 void prepare_packed_git(void)
520 {
521         static int run_once = 0;
522         struct alternate_object_database *alt;
523
524         if (run_once)
525                 return;
526         prepare_packed_git_one(get_object_directory(), 1);
527         prepare_alt_odb();
528         for (alt = alt_odb_list; alt; alt = alt->next) {
529                 alt->name[0] = 0;
530                 prepare_packed_git_one(alt->base, 0);
531         }
532         run_once = 1;
533 }
534
535 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
536 {
537         char header[100];
538         unsigned char real_sha1[20];
539         SHA_CTX c;
540
541         SHA1_Init(&c);
542         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
543         SHA1_Update(&c, map, size);
544         SHA1_Final(real_sha1, &c);
545         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
546 }
547
548 static void *map_sha1_file_internal(const unsigned char *sha1,
549                                     unsigned long *size)
550 {
551         struct stat st;
552         void *map;
553         int fd;
554         char *filename = find_sha1_file(sha1, &st);
555
556         if (!filename) {
557                 return NULL;
558         }
559
560         fd = open(filename, O_RDONLY | sha1_file_open_flag);
561         if (fd < 0) {
562                 /* See if it works without O_NOATIME */
563                 switch (sha1_file_open_flag) {
564                 default:
565                         fd = open(filename, O_RDONLY);
566                         if (fd >= 0)
567                                 break;
568                 /* Fallthrough */
569                 case 0:
570                         return NULL;
571                 }
572
573                 /* If it failed once, it will probably fail again.
574                  * Stop using O_NOATIME
575                  */
576                 sha1_file_open_flag = 0;
577         }
578         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
579         close(fd);
580         if (map == MAP_FAILED)
581                 return NULL;
582         *size = st.st_size;
583         return map;
584 }
585
586 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
587 {
588         /* Get the data stream */
589         memset(stream, 0, sizeof(*stream));
590         stream->next_in = map;
591         stream->avail_in = mapsize;
592         stream->next_out = buffer;
593         stream->avail_out = size;
594
595         inflateInit(stream);
596         return inflate(stream, 0);
597 }
598
599 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
600 {
601         int bytes = strlen(buffer) + 1;
602         unsigned char *buf = xmalloc(1+size);
603
604         memcpy(buf, buffer + bytes, stream->total_out - bytes);
605         bytes = stream->total_out - bytes;
606         if (bytes < size) {
607                 stream->next_out = buf + bytes;
608                 stream->avail_out = size - bytes;
609                 while (inflate(stream, Z_FINISH) == Z_OK)
610                         /* nothing */;
611         }
612         buf[size] = 0;
613         inflateEnd(stream);
614         return buf;
615 }
616
617 /*
618  * We used to just use "sscanf()", but that's actually way
619  * too permissive for what we want to check. So do an anal
620  * object header parse by hand.
621  */
622 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
623 {
624         int i;
625         unsigned long size;
626
627         /*
628          * The type can be at most ten bytes (including the 
629          * terminating '\0' that we add), and is followed by
630          * a space. 
631          */
632         i = 10;
633         for (;;) {
634                 char c = *hdr++;
635                 if (c == ' ')
636                         break;
637                 if (!--i)
638                         return -1;
639                 *type++ = c;
640         }
641         *type = 0;
642
643         /*
644          * The length must follow immediately, and be in canonical
645          * decimal format (ie "010" is not valid).
646          */
647         size = *hdr++ - '0';
648         if (size > 9)
649                 return -1;
650         if (size) {
651                 for (;;) {
652                         unsigned long c = *hdr - '0';
653                         if (c > 9)
654                                 break;
655                         hdr++;
656                         size = size * 10 + c;
657                 }
658         }
659         *sizep = size;
660
661         /*
662          * The length must be followed by a zero byte
663          */
664         return *hdr ? -1 : 0;
665 }
666
667 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
668 {
669         int ret;
670         z_stream stream;
671         char hdr[8192];
672
673         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
674         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
675                 return NULL;
676
677         return unpack_sha1_rest(&stream, hdr, *size);
678 }
679
680 /* forward declaration for a mutually recursive function */
681 static int packed_object_info(struct pack_entry *entry,
682                               char *type, unsigned long *sizep);
683
684 static int packed_delta_info(unsigned char *base_sha1,
685                              unsigned long delta_size,
686                              unsigned long left,
687                              char *type,
688                              unsigned long *sizep,
689                              struct packed_git *p)
690 {
691         struct pack_entry base_ent;
692
693         if (left < 20)
694                 die("truncated pack file");
695
696         /* The base entry _must_ be in the same pack */
697         if (!find_pack_entry_one(base_sha1, &base_ent, p))
698                 die("failed to find delta-pack base object %s",
699                     sha1_to_hex(base_sha1));
700
701         /* We choose to only get the type of the base object and
702          * ignore potentially corrupt pack file that expects the delta
703          * based on a base with a wrong size.  This saves tons of
704          * inflate() calls.
705          */
706
707         if (packed_object_info(&base_ent, type, NULL))
708                 die("cannot get info for delta-pack base");
709
710         if (sizep) {
711                 const unsigned char *data;
712                 unsigned char delta_head[64];
713                 unsigned long result_size;
714                 z_stream stream;
715                 int st;
716
717                 memset(&stream, 0, sizeof(stream));
718
719                 data = stream.next_in = base_sha1 + 20;
720                 stream.avail_in = left - 20;
721                 stream.next_out = delta_head;
722                 stream.avail_out = sizeof(delta_head);
723
724                 inflateInit(&stream);
725                 st = inflate(&stream, Z_FINISH);
726                 inflateEnd(&stream);
727                 if ((st != Z_STREAM_END) &&
728                     stream.total_out != sizeof(delta_head))
729                         die("delta data unpack-initial failed");
730
731                 /* Examine the initial part of the delta to figure out
732                  * the result size.
733                  */
734                 data = delta_head;
735                 get_delta_hdr_size(&data); /* ignore base size */
736
737                 /* Read the result size */
738                 result_size = get_delta_hdr_size(&data);
739                 *sizep = result_size;
740         }
741         return 0;
742 }
743
744 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
745         enum object_type *type, unsigned long *sizep)
746 {
747         unsigned shift;
748         unsigned char *pack, c;
749         unsigned long size;
750
751         if (offset >= p->pack_size)
752                 die("object offset outside of pack file");
753
754         pack =  p->pack_base + offset;
755         c = *pack++;
756         offset++;
757         *type = (c >> 4) & 7;
758         size = c & 15;
759         shift = 4;
760         while (c & 0x80) {
761                 if (offset >= p->pack_size)
762                         die("object offset outside of pack file");
763                 c = *pack++;
764                 offset++;
765                 size += (c & 0x7f) << shift;
766                 shift += 7;
767         }
768         *sizep = size;
769         return offset;
770 }
771
772 void packed_object_info_detail(struct pack_entry *e,
773                                char *type,
774                                unsigned long *size,
775                                unsigned long *store_size,
776                                int *delta_chain_length,
777                                unsigned char *base_sha1)
778 {
779         struct packed_git *p = e->p;
780         unsigned long offset, left;
781         unsigned char *pack;
782         enum object_type kind;
783
784         offset = unpack_object_header(p, e->offset, &kind, size);
785         pack = p->pack_base + offset;
786         left = p->pack_size - offset;
787         if (kind != OBJ_DELTA)
788                 *delta_chain_length = 0;
789         else {
790                 int chain_length = 0;
791                 memcpy(base_sha1, pack, 20);
792                 do {
793                         struct pack_entry base_ent;
794                         unsigned long junk;
795
796                         find_pack_entry_one(pack, &base_ent, p);
797                         offset = unpack_object_header(p, base_ent.offset,
798                                                       &kind, &junk);
799                         pack = p->pack_base + offset;
800                         chain_length++;
801                 } while (kind == OBJ_DELTA);
802                 *delta_chain_length = chain_length;
803         }
804         switch (kind) {
805         case OBJ_COMMIT:
806                 strcpy(type, "commit");
807                 break;
808         case OBJ_TREE:
809                 strcpy(type, "tree");
810                 break;
811         case OBJ_BLOB:
812                 strcpy(type, "blob");
813                 break;
814         case OBJ_TAG:
815                 strcpy(type, "tag");
816                 break;
817         default:
818                 die("corrupted pack file %s containing object of kind %d",
819                     p->pack_name, kind);
820         }
821         *store_size = 0; /* notyet */
822 }
823
824 static int packed_object_info(struct pack_entry *entry,
825                               char *type, unsigned long *sizep)
826 {
827         struct packed_git *p = entry->p;
828         unsigned long offset, size, left;
829         unsigned char *pack;
830         enum object_type kind;
831         int retval;
832
833         if (use_packed_git(p))
834                 die("cannot map packed file");
835
836         offset = unpack_object_header(p, entry->offset, &kind, &size);
837         pack = p->pack_base + offset;
838         left = p->pack_size - offset;
839
840         switch (kind) {
841         case OBJ_DELTA:
842                 retval = packed_delta_info(pack, size, left, type, sizep, p);
843                 unuse_packed_git(p);
844                 return retval;
845         case OBJ_COMMIT:
846                 strcpy(type, "commit");
847                 break;
848         case OBJ_TREE:
849                 strcpy(type, "tree");
850                 break;
851         case OBJ_BLOB:
852                 strcpy(type, "blob");
853                 break;
854         case OBJ_TAG:
855                 strcpy(type, "tag");
856                 break;
857         default:
858                 die("corrupted pack file %s containing object of kind %d",
859                     p->pack_name, kind);
860         }
861         if (sizep)
862                 *sizep = size;
863         unuse_packed_git(p);
864         return 0;
865 }
866
867 /* forward declaration for a mutually recursive function */
868 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
869
870 static void *unpack_delta_entry(unsigned char *base_sha1,
871                                 unsigned long delta_size,
872                                 unsigned long left,
873                                 char *type,
874                                 unsigned long *sizep,
875                                 struct packed_git *p)
876 {
877         struct pack_entry base_ent;
878         void *data, *delta_data, *result, *base;
879         unsigned long data_size, result_size, base_size;
880         z_stream stream;
881         int st;
882
883         if (left < 20)
884                 die("truncated pack file");
885         data = base_sha1 + 20;
886         data_size = left - 20;
887         delta_data = xmalloc(delta_size);
888
889         memset(&stream, 0, sizeof(stream));
890
891         stream.next_in = data;
892         stream.avail_in = data_size;
893         stream.next_out = delta_data;
894         stream.avail_out = delta_size;
895
896         inflateInit(&stream);
897         st = inflate(&stream, Z_FINISH);
898         inflateEnd(&stream);
899         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
900                 die("delta data unpack failed");
901
902         /* The base entry _must_ be in the same pack */
903         if (!find_pack_entry_one(base_sha1, &base_ent, p))
904                 die("failed to find delta-pack base object %s",
905                     sha1_to_hex(base_sha1));
906         base = unpack_entry_gently(&base_ent, type, &base_size);
907         if (!base)
908                 die("failed to read delta-pack base object %s",
909                     sha1_to_hex(base_sha1));
910         result = patch_delta(base, base_size,
911                              delta_data, delta_size,
912                              &result_size);
913         if (!result)
914                 die("failed to apply delta");
915         free(delta_data);
916         free(base);
917         *sizep = result_size;
918         return result;
919 }
920
921 static void *unpack_non_delta_entry(unsigned char *data,
922                                     unsigned long size,
923                                     unsigned long left)
924 {
925         int st;
926         z_stream stream;
927         unsigned char *buffer;
928
929         buffer = xmalloc(size + 1);
930         buffer[size] = 0;
931         memset(&stream, 0, sizeof(stream));
932         stream.next_in = data;
933         stream.avail_in = left;
934         stream.next_out = buffer;
935         stream.avail_out = size;
936
937         inflateInit(&stream);
938         st = inflate(&stream, Z_FINISH);
939         inflateEnd(&stream);
940         if ((st != Z_STREAM_END) || stream.total_out != size) {
941                 free(buffer);
942                 return NULL;
943         }
944
945         return buffer;
946 }
947
948 static void *unpack_entry(struct pack_entry *entry,
949                           char *type, unsigned long *sizep)
950 {
951         struct packed_git *p = entry->p;
952         void *retval;
953
954         if (use_packed_git(p))
955                 die("cannot map packed file");
956         retval = unpack_entry_gently(entry, type, sizep);
957         unuse_packed_git(p);
958         if (!retval)
959                 die("corrupted pack file %s", p->pack_name);
960         return retval;
961 }
962
963 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
964 void *unpack_entry_gently(struct pack_entry *entry,
965                           char *type, unsigned long *sizep)
966 {
967         struct packed_git *p = entry->p;
968         unsigned long offset, size, left;
969         unsigned char *pack;
970         enum object_type kind;
971         void *retval;
972
973         offset = unpack_object_header(p, entry->offset, &kind, &size);
974         pack = p->pack_base + offset;
975         left = p->pack_size - offset;
976         switch (kind) {
977         case OBJ_DELTA:
978                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
979                 return retval;
980         case OBJ_COMMIT:
981                 strcpy(type, "commit");
982                 break;
983         case OBJ_TREE:
984                 strcpy(type, "tree");
985                 break;
986         case OBJ_BLOB:
987                 strcpy(type, "blob");
988                 break;
989         case OBJ_TAG:
990                 strcpy(type, "tag");
991                 break;
992         default:
993                 return NULL;
994         }
995         *sizep = size;
996         retval = unpack_non_delta_entry(pack, size, left);
997         return retval;
998 }
999
1000 int num_packed_objects(const struct packed_git *p)
1001 {
1002         /* See check_packed_git_idx() */
1003         return (p->index_size - 20 - 20 - 4*256) / 24;
1004 }
1005
1006 int nth_packed_object_sha1(const struct packed_git *p, int n,
1007                            unsigned char* sha1)
1008 {
1009         void *index = p->index_base + 256;
1010         if (n < 0 || num_packed_objects(p) <= n)
1011                 return -1;
1012         memcpy(sha1, (index + 24 * n + 4), 20);
1013         return 0;
1014 }
1015
1016 int find_pack_entry_one(const unsigned char *sha1,
1017                         struct pack_entry *e, struct packed_git *p)
1018 {
1019         unsigned int *level1_ofs = p->index_base;
1020         int hi = ntohl(level1_ofs[*sha1]);
1021         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1022         void *index = p->index_base + 256;
1023
1024         do {
1025                 int mi = (lo + hi) / 2;
1026                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1027                 if (!cmp) {
1028                         e->offset = ntohl(*((int*)(index + 24 * mi)));
1029                         memcpy(e->sha1, sha1, 20);
1030                         e->p = p;
1031                         return 1;
1032                 }
1033                 if (cmp > 0)
1034                         hi = mi;
1035                 else
1036                         lo = mi+1;
1037         } while (lo < hi);
1038         return 0;
1039 }
1040
1041 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1042 {
1043         struct packed_git *p;
1044         prepare_packed_git();
1045
1046         for (p = packed_git; p; p = p->next) {
1047                 if (find_pack_entry_one(sha1, e, p))
1048                         return 1;
1049         }
1050         return 0;
1051 }
1052
1053 struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1054                                   struct packed_git *packs)
1055 {
1056         struct packed_git *p;
1057         struct pack_entry e;
1058
1059         for (p = packs; p; p = p->next) {
1060                 if (find_pack_entry_one(sha1, &e, p))
1061                         return p;
1062         }
1063         return NULL;
1064         
1065 }
1066
1067 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1068 {
1069         int status;
1070         unsigned long mapsize, size;
1071         void *map;
1072         z_stream stream;
1073         char hdr[128];
1074
1075         map = map_sha1_file_internal(sha1, &mapsize);
1076         if (!map) {
1077                 struct pack_entry e;
1078
1079                 if (!find_pack_entry(sha1, &e))
1080                         return error("unable to find %s", sha1_to_hex(sha1));
1081                 return packed_object_info(&e, type, sizep);
1082         }
1083         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1084                 status = error("unable to unpack %s header",
1085                                sha1_to_hex(sha1));
1086         if (parse_sha1_header(hdr, type, &size) < 0)
1087                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1088         else {
1089                 status = 0;
1090                 if (sizep)
1091                         *sizep = size;
1092         }
1093         inflateEnd(&stream);
1094         munmap(map, mapsize);
1095         return status;
1096 }
1097
1098 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1099 {
1100         struct pack_entry e;
1101
1102         if (!find_pack_entry(sha1, &e)) {
1103                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1104                 return NULL;
1105         }
1106         return unpack_entry(&e, type, size);
1107 }
1108
1109 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1110 {
1111         unsigned long mapsize;
1112         void *map, *buf;
1113         struct pack_entry e;
1114
1115         if (find_pack_entry(sha1, &e))
1116                 return read_packed_sha1(sha1, type, size);
1117         map = map_sha1_file_internal(sha1, &mapsize);
1118         if (map) {
1119                 buf = unpack_sha1_file(map, mapsize, type, size);
1120                 munmap(map, mapsize);
1121                 return buf;
1122         }
1123         return NULL;
1124 }
1125
1126 void *read_object_with_reference(const unsigned char *sha1,
1127                                  const char *required_type,
1128                                  unsigned long *size,
1129                                  unsigned char *actual_sha1_return)
1130 {
1131         char type[20];
1132         void *buffer;
1133         unsigned long isize;
1134         unsigned char actual_sha1[20];
1135
1136         memcpy(actual_sha1, sha1, 20);
1137         while (1) {
1138                 int ref_length = -1;
1139                 const char *ref_type = NULL;
1140
1141                 buffer = read_sha1_file(actual_sha1, type, &isize);
1142                 if (!buffer)
1143                         return NULL;
1144                 if (!strcmp(type, required_type)) {
1145                         *size = isize;
1146                         if (actual_sha1_return)
1147                                 memcpy(actual_sha1_return, actual_sha1, 20);
1148                         return buffer;
1149                 }
1150                 /* Handle references */
1151                 else if (!strcmp(type, "commit"))
1152                         ref_type = "tree ";
1153                 else if (!strcmp(type, "tag"))
1154                         ref_type = "object ";
1155                 else {
1156                         free(buffer);
1157                         return NULL;
1158                 }
1159                 ref_length = strlen(ref_type);
1160
1161                 if (memcmp(buffer, ref_type, ref_length) ||
1162                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1163                         free(buffer);
1164                         return NULL;
1165                 }
1166                 free(buffer);
1167                 /* Now we have the ID of the referred-to object in
1168                  * actual_sha1.  Check again. */
1169         }
1170 }
1171
1172 char *write_sha1_file_prepare(void *buf,
1173                               unsigned long len,
1174                               const char *type,
1175                               unsigned char *sha1,
1176                               unsigned char *hdr,
1177                               int *hdrlen)
1178 {
1179         SHA_CTX c;
1180
1181         /* Generate the header */
1182         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1183
1184         /* Sha1.. */
1185         SHA1_Init(&c);
1186         SHA1_Update(&c, hdr, *hdrlen);
1187         SHA1_Update(&c, buf, len);
1188         SHA1_Final(sha1, &c);
1189
1190         return sha1_file_name(sha1);
1191 }
1192
1193 /*
1194  * Link the tempfile to the final place, possibly creating the
1195  * last directory level as you do so.
1196  *
1197  * Returns the errno on failure, 0 on success.
1198  */
1199 static int link_temp_to_file(const char *tmpfile, char *filename)
1200 {
1201         int ret;
1202
1203         if (!link(tmpfile, filename))
1204                 return 0;
1205
1206         /*
1207          * Try to mkdir the last path component if that failed
1208          * with an ENOENT.
1209          *
1210          * Re-try the "link()" regardless of whether the mkdir
1211          * succeeds, since a race might mean that somebody
1212          * else succeeded.
1213          */
1214         ret = errno;
1215         if (ret == ENOENT) {
1216                 char *dir = strrchr(filename, '/');
1217                 if (dir) {
1218                         *dir = 0;
1219                         mkdir(filename, 0777);
1220                         *dir = '/';
1221                         if (!link(tmpfile, filename))
1222                                 return 0;
1223                         ret = errno;
1224                 }
1225         }
1226         return ret;
1227 }
1228
1229 /*
1230  * Move the just written object into its final resting place
1231  */
1232 int move_temp_to_file(const char *tmpfile, char *filename)
1233 {
1234         int ret = link_temp_to_file(tmpfile, filename);
1235         if (ret) {
1236                 /*
1237                  * Coda hack - coda doesn't like cross-directory links,
1238                  * so we fall back to a rename, which will mean that it
1239                  * won't be able to check collisions, but that's not a
1240                  * big deal.
1241                  *
1242                  * When this succeeds, we just return 0. We have nothing
1243                  * left to unlink.
1244                  */
1245                 if (ret == EXDEV && !rename(tmpfile, filename))
1246                         return 0;
1247         }
1248         unlink(tmpfile);
1249         if (ret) {
1250                 if (ret != EEXIST) {
1251                         fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1252                         return -1;
1253                 }
1254                 /* FIXME!!! Collision check here ? */
1255         }
1256
1257         return 0;
1258 }
1259
1260 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1261 {
1262         int size;
1263         unsigned char *compressed;
1264         z_stream stream;
1265         unsigned char sha1[20];
1266         char *filename;
1267         static char tmpfile[PATH_MAX];
1268         unsigned char hdr[50];
1269         int fd, hdrlen;
1270
1271         /* Normally if we have it in the pack then we do not bother writing
1272          * it out into .git/objects/??/?{38} file.
1273          */
1274         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1275         if (returnsha1)
1276                 memcpy(returnsha1, sha1, 20);
1277         if (has_sha1_file(sha1))
1278                 return 0;
1279         fd = open(filename, O_RDONLY);
1280         if (fd >= 0) {
1281                 /*
1282                  * FIXME!!! We might do collision checking here, but we'd
1283                  * need to uncompress the old file and check it. Later.
1284                  */
1285                 close(fd);
1286                 return 0;
1287         }
1288
1289         if (errno != ENOENT) {
1290                 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1291                 return -1;
1292         }
1293
1294         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1295
1296         fd = mkstemp(tmpfile);
1297         if (fd < 0) {
1298                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1299                 return -1;
1300         }
1301
1302         /* Set it up */
1303         memset(&stream, 0, sizeof(stream));
1304         deflateInit(&stream, Z_BEST_COMPRESSION);
1305         size = deflateBound(&stream, len+hdrlen);
1306         compressed = xmalloc(size);
1307
1308         /* Compress it */
1309         stream.next_out = compressed;
1310         stream.avail_out = size;
1311
1312         /* First header.. */
1313         stream.next_in = hdr;
1314         stream.avail_in = hdrlen;
1315         while (deflate(&stream, 0) == Z_OK)
1316                 /* nothing */;
1317
1318         /* Then the data itself.. */
1319         stream.next_in = buf;
1320         stream.avail_in = len;
1321         while (deflate(&stream, Z_FINISH) == Z_OK)
1322                 /* nothing */;
1323         deflateEnd(&stream);
1324         size = stream.total_out;
1325
1326         if (write(fd, compressed, size) != size)
1327                 die("unable to write file");
1328         fchmod(fd, 0444);
1329         close(fd);
1330         free(compressed);
1331
1332         return move_temp_to_file(tmpfile, filename);
1333 }
1334
1335 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1336 {
1337         ssize_t size;
1338         unsigned long objsize;
1339         int posn = 0;
1340         void *map = map_sha1_file_internal(sha1, &objsize);
1341         void *buf = map;
1342         void *temp_obj = NULL;
1343         z_stream stream;
1344
1345         if (!buf) {
1346                 unsigned char *unpacked;
1347                 unsigned long len;
1348                 char type[20];
1349                 char hdr[50];
1350                 int hdrlen;
1351                 // need to unpack and recompress it by itself
1352                 unpacked = read_packed_sha1(sha1, type, &len);
1353
1354                 hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1355
1356                 /* Set it up */
1357                 memset(&stream, 0, sizeof(stream));
1358                 deflateInit(&stream, Z_BEST_COMPRESSION);
1359                 size = deflateBound(&stream, len + hdrlen);
1360                 temp_obj = buf = xmalloc(size);
1361
1362                 /* Compress it */
1363                 stream.next_out = buf;
1364                 stream.avail_out = size;
1365                 
1366                 /* First header.. */
1367                 stream.next_in = (void *)hdr;
1368                 stream.avail_in = hdrlen;
1369                 while (deflate(&stream, 0) == Z_OK)
1370                         /* nothing */;
1371
1372                 /* Then the data itself.. */
1373                 stream.next_in = unpacked;
1374                 stream.avail_in = len;
1375                 while (deflate(&stream, Z_FINISH) == Z_OK)
1376                         /* nothing */;
1377                 deflateEnd(&stream);
1378                 free(unpacked);
1379                 
1380                 objsize = stream.total_out;
1381         }
1382
1383         do {
1384                 size = write(fd, buf + posn, objsize - posn);
1385                 if (size <= 0) {
1386                         if (!size) {
1387                                 fprintf(stderr, "write closed");
1388                         } else {
1389                                 perror("write ");
1390                         }
1391                         return -1;
1392                 }
1393                 posn += size;
1394         } while (posn < objsize);
1395
1396         if (map)
1397                 munmap(map, objsize);
1398         if (temp_obj)
1399                 free(temp_obj);
1400
1401         return 0;
1402 }
1403
1404 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1405                        size_t bufsize, size_t *bufposn)
1406 {
1407         char tmpfile[PATH_MAX];
1408         int local;
1409         z_stream stream;
1410         unsigned char real_sha1[20];
1411         unsigned char discard[4096];
1412         int ret;
1413         SHA_CTX c;
1414
1415         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1416
1417         local = mkstemp(tmpfile);
1418         if (local < 0)
1419                 return error("Couldn't open %s for %s\n", tmpfile, sha1_to_hex(sha1));
1420
1421         memset(&stream, 0, sizeof(stream));
1422
1423         inflateInit(&stream);
1424
1425         SHA1_Init(&c);
1426
1427         do {
1428                 ssize_t size;
1429                 if (*bufposn) {
1430                         stream.avail_in = *bufposn;
1431                         stream.next_in = (unsigned char *) buffer;
1432                         do {
1433                                 stream.next_out = discard;
1434                                 stream.avail_out = sizeof(discard);
1435                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1436                                 SHA1_Update(&c, discard, sizeof(discard) -
1437                                             stream.avail_out);
1438                         } while (stream.avail_in && ret == Z_OK);
1439                         write(local, buffer, *bufposn - stream.avail_in);
1440                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1441                                 stream.avail_in);
1442                         *bufposn = stream.avail_in;
1443                         if (ret != Z_OK)
1444                                 break;
1445                 }
1446                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1447                 if (size <= 0) {
1448                         close(local);
1449                         unlink(tmpfile);
1450                         if (!size)
1451                                 return error("Connection closed?");
1452                         perror("Reading from connection");
1453                         return -1;
1454                 }
1455                 *bufposn += size;
1456         } while (1);
1457         inflateEnd(&stream);
1458
1459         close(local);
1460         SHA1_Final(real_sha1, &c);
1461         if (ret != Z_STREAM_END) {
1462                 unlink(tmpfile);
1463                 return error("File %s corrupted", sha1_to_hex(sha1));
1464         }
1465         if (memcmp(sha1, real_sha1, 20)) {
1466                 unlink(tmpfile);
1467                 return error("File %s has bad hash\n", sha1_to_hex(sha1));
1468         }
1469
1470         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1471 }
1472
1473 int has_pack_index(const unsigned char *sha1)
1474 {
1475         struct stat st;
1476         if (stat(sha1_pack_index_name(sha1), &st))
1477                 return 0;
1478         return 1;
1479 }
1480
1481 int has_pack_file(const unsigned char *sha1)
1482 {
1483         struct stat st;
1484         if (stat(sha1_pack_name(sha1), &st))
1485                 return 0;
1486         return 1;
1487 }
1488
1489 int has_sha1_pack(const unsigned char *sha1)
1490 {
1491         struct pack_entry e;
1492         return find_pack_entry(sha1, &e);
1493 }
1494
1495 int has_sha1_file(const unsigned char *sha1)
1496 {
1497         struct stat st;
1498         struct pack_entry e;
1499
1500         if (find_pack_entry(sha1, &e))
1501                 return 1;
1502         return find_sha1_file(sha1, &st) ? 1 : 0;
1503 }
1504
1505 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1506 {
1507         unsigned long size = st->st_size;
1508         void *buf;
1509         int ret;
1510         unsigned char hdr[50];
1511         int hdrlen;
1512
1513         buf = "";
1514         if (size)
1515                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1516         close(fd);
1517         if (buf == MAP_FAILED)
1518                 return -1;
1519
1520         if (!type)
1521                 type = "blob";
1522         if (write_object)
1523                 ret = write_sha1_file(buf, size, type, sha1);
1524         else {
1525                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1526                 ret = 0;
1527         }
1528         if (size)
1529                 munmap(buf, size);
1530         return ret;
1531 }
1532
1533 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1534 {
1535         int fd;
1536         char *target;
1537
1538         switch (st->st_mode & S_IFMT) {
1539         case S_IFREG:
1540                 fd = open(path, O_RDONLY);
1541                 if (fd < 0)
1542                         return error("open(\"%s\"): %s", path,
1543                                      strerror(errno));
1544                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1545                         return error("%s: failed to insert into database",
1546                                      path);
1547                 break;
1548         case S_IFLNK:
1549                 target = xmalloc(st->st_size+1);
1550                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1551                         char *errstr = strerror(errno);
1552                         free(target);
1553                         return error("readlink(\"%s\"): %s", path,
1554                                      errstr);
1555                 }
1556                 if (!write_object) {
1557                         unsigned char hdr[50];
1558                         int hdrlen;
1559                         write_sha1_file_prepare(target, st->st_size, "blob",
1560                                                 sha1, hdr, &hdrlen);
1561                 } else if (write_sha1_file(target, st->st_size, "blob", sha1))
1562                         return error("%s: failed to insert into database",
1563                                      path);
1564                 free(target);
1565                 break;
1566         default:
1567                 return error("%s: unsupported file type", path);
1568         }
1569         return 0;
1570 }