Document why header parsing won't exceed a window.
[git] / index-pack.c
1 #include "cache.h"
2 #include "delta.h"
3 #include "pack.h"
4 #include "csum-file.h"
5 #include "blob.h"
6 #include "commit.h"
7 #include "tag.h"
8 #include "tree.h"
9
10 static const char index_pack_usage[] =
11 "git-index-pack [-v] [-o <index-file>] [{ ---keep | --keep=<msg> }] { <pack-file> | --stdin [--fix-thin] [<pack-file>] }";
12
13 struct object_entry
14 {
15         unsigned long offset;
16         unsigned long size;
17         unsigned int hdr_size;
18         enum object_type type;
19         enum object_type real_type;
20         unsigned char sha1[20];
21 };
22
23 union delta_base {
24         unsigned char sha1[20];
25         unsigned long offset;
26 };
27
28 /*
29  * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
30  * to memcmp() only the first 20 bytes.
31  */
32 #define UNION_BASE_SZ   20
33
34 struct delta_entry
35 {
36         union delta_base base;
37         int obj_no;
38 };
39
40 static struct object_entry *objects;
41 static struct delta_entry *deltas;
42 static int nr_objects;
43 static int nr_deltas;
44 static int nr_resolved_deltas;
45
46 static int from_stdin;
47 static int verbose;
48
49 static volatile sig_atomic_t progress_update;
50
51 static void progress_interval(int signum)
52 {
53         progress_update = 1;
54 }
55
56 static void setup_progress_signal(void)
57 {
58         struct sigaction sa;
59         struct itimerval v;
60
61         memset(&sa, 0, sizeof(sa));
62         sa.sa_handler = progress_interval;
63         sigemptyset(&sa.sa_mask);
64         sa.sa_flags = SA_RESTART;
65         sigaction(SIGALRM, &sa, NULL);
66
67         v.it_interval.tv_sec = 1;
68         v.it_interval.tv_usec = 0;
69         v.it_value = v.it_interval;
70         setitimer(ITIMER_REAL, &v, NULL);
71
72 }
73
74 static unsigned display_progress(unsigned n, unsigned total, unsigned last_pc)
75 {
76         unsigned percent = n * 100 / total;
77         if (percent != last_pc || progress_update) {
78                 fprintf(stderr, "%4u%% (%u/%u) done\r", percent, n, total);
79                 progress_update = 0;
80         }
81         return percent;
82 }
83
84 /* We always read in 4kB chunks. */
85 static unsigned char input_buffer[4096];
86 static unsigned long input_offset, input_len, consumed_bytes;
87 static SHA_CTX input_ctx;
88 static int input_fd, output_fd, pack_fd;
89
90 /* Discard current buffer used content. */
91 static void flush(void)
92 {
93         if (input_offset) {
94                 if (output_fd >= 0)
95                         write_or_die(output_fd, input_buffer, input_offset);
96                 SHA1_Update(&input_ctx, input_buffer, input_offset);
97                 memmove(input_buffer, input_buffer + input_offset, input_len);
98                 input_offset = 0;
99         }
100 }
101
102 /*
103  * Make sure at least "min" bytes are available in the buffer, and
104  * return the pointer to the buffer.
105  */
106 static void *fill(int min)
107 {
108         if (min <= input_len)
109                 return input_buffer + input_offset;
110         if (min > sizeof(input_buffer))
111                 die("cannot fill %d bytes", min);
112         flush();
113         do {
114                 int ret = xread(input_fd, input_buffer + input_len,
115                                 sizeof(input_buffer) - input_len);
116                 if (ret <= 0) {
117                         if (!ret)
118                                 die("early EOF");
119                         die("read error on input: %s", strerror(errno));
120                 }
121                 input_len += ret;
122         } while (input_len < min);
123         return input_buffer;
124 }
125
126 static void use(int bytes)
127 {
128         if (bytes > input_len)
129                 die("used more bytes than were available");
130         input_len -= bytes;
131         input_offset += bytes;
132         consumed_bytes += bytes;
133 }
134
135 static const char *open_pack_file(const char *pack_name)
136 {
137         if (from_stdin) {
138                 input_fd = 0;
139                 if (!pack_name) {
140                         static char tmpfile[PATH_MAX];
141                         snprintf(tmpfile, sizeof(tmpfile),
142                                  "%s/pack_XXXXXX", get_object_directory());
143                         output_fd = mkstemp(tmpfile);
144                         pack_name = xstrdup(tmpfile);
145                 } else
146                         output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
147                 if (output_fd < 0)
148                         die("unable to create %s: %s\n", pack_name, strerror(errno));
149                 pack_fd = output_fd;
150         } else {
151                 input_fd = open(pack_name, O_RDONLY);
152                 if (input_fd < 0)
153                         die("cannot open packfile '%s': %s",
154                             pack_name, strerror(errno));
155                 output_fd = -1;
156                 pack_fd = input_fd;
157         }
158         SHA1_Init(&input_ctx);
159         return pack_name;
160 }
161
162 static void parse_pack_header(void)
163 {
164         struct pack_header *hdr = fill(sizeof(struct pack_header));
165
166         /* Header consistency check */
167         if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
168                 die("pack signature mismatch");
169         if (!pack_version_ok(hdr->hdr_version))
170                 die("pack version %d unsupported", ntohl(hdr->hdr_version));
171
172         nr_objects = ntohl(hdr->hdr_entries);
173         use(sizeof(struct pack_header));
174 }
175
176 static void bad_object(unsigned long offset, const char *format,
177                        ...) NORETURN __attribute__((format (printf, 2, 3)));
178
179 static void bad_object(unsigned long offset, const char *format, ...)
180 {
181         va_list params;
182         char buf[1024];
183
184         va_start(params, format);
185         vsnprintf(buf, sizeof(buf), format, params);
186         va_end(params);
187         die("pack has bad object at offset %lu: %s", offset, buf);
188 }
189
190 static void *unpack_entry_data(unsigned long offset, unsigned long size)
191 {
192         z_stream stream;
193         void *buf = xmalloc(size);
194
195         memset(&stream, 0, sizeof(stream));
196         stream.next_out = buf;
197         stream.avail_out = size;
198         stream.next_in = fill(1);
199         stream.avail_in = input_len;
200         inflateInit(&stream);
201
202         for (;;) {
203                 int ret = inflate(&stream, 0);
204                 use(input_len - stream.avail_in);
205                 if (stream.total_out == size && ret == Z_STREAM_END)
206                         break;
207                 if (ret != Z_OK)
208                         bad_object(offset, "inflate returned %d", ret);
209                 stream.next_in = fill(1);
210                 stream.avail_in = input_len;
211         }
212         inflateEnd(&stream);
213         return buf;
214 }
215
216 static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_base)
217 {
218         unsigned char *p, c;
219         unsigned long size, base_offset;
220         unsigned shift;
221
222         obj->offset = consumed_bytes;
223
224         p = fill(1);
225         c = *p;
226         use(1);
227         obj->type = (c >> 4) & 7;
228         size = (c & 15);
229         shift = 4;
230         while (c & 0x80) {
231                 p = fill(1);
232                 c = *p;
233                 use(1);
234                 size += (c & 0x7fUL) << shift;
235                 shift += 7;
236         }
237         obj->size = size;
238
239         switch (obj->type) {
240         case OBJ_REF_DELTA:
241                 hashcpy(delta_base->sha1, fill(20));
242                 use(20);
243                 break;
244         case OBJ_OFS_DELTA:
245                 memset(delta_base, 0, sizeof(*delta_base));
246                 p = fill(1);
247                 c = *p;
248                 use(1);
249                 base_offset = c & 127;
250                 while (c & 128) {
251                         base_offset += 1;
252                         if (!base_offset || base_offset & ~(~0UL >> 7))
253                                 bad_object(obj->offset, "offset value overflow for delta base object");
254                         p = fill(1);
255                         c = *p;
256                         use(1);
257                         base_offset = (base_offset << 7) + (c & 127);
258                 }
259                 delta_base->offset = obj->offset - base_offset;
260                 if (delta_base->offset >= obj->offset)
261                         bad_object(obj->offset, "delta base offset is out of bound");
262                 break;
263         case OBJ_COMMIT:
264         case OBJ_TREE:
265         case OBJ_BLOB:
266         case OBJ_TAG:
267                 break;
268         default:
269                 bad_object(obj->offset, "unknown object type %d", obj->type);
270         }
271         obj->hdr_size = consumed_bytes - obj->offset;
272
273         return unpack_entry_data(obj->offset, obj->size);
274 }
275
276 static void *get_data_from_pack(struct object_entry *obj)
277 {
278         unsigned long from = obj[0].offset + obj[0].hdr_size;
279         unsigned long len = obj[1].offset - from;
280         unsigned char *src, *data;
281         z_stream stream;
282         int st;
283
284         src = xmalloc(len);
285         if (pread(pack_fd, src, len, from) != len)
286                 die("cannot pread pack file: %s", strerror(errno));
287         data = xmalloc(obj->size);
288         memset(&stream, 0, sizeof(stream));
289         stream.next_out = data;
290         stream.avail_out = obj->size;
291         stream.next_in = src;
292         stream.avail_in = len;
293         inflateInit(&stream);
294         while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
295         inflateEnd(&stream);
296         if (st != Z_STREAM_END || stream.total_out != obj->size)
297                 die("serious inflate inconsistency");
298         free(src);
299         return data;
300 }
301
302 static int find_delta(const union delta_base *base)
303 {
304         int first = 0, last = nr_deltas;
305
306         while (first < last) {
307                 int next = (first + last) / 2;
308                 struct delta_entry *delta = &deltas[next];
309                 int cmp;
310
311                 cmp = memcmp(base, &delta->base, UNION_BASE_SZ);
312                 if (!cmp)
313                         return next;
314                 if (cmp < 0) {
315                         last = next;
316                         continue;
317                 }
318                 first = next+1;
319         }
320         return -first-1;
321 }
322
323 static int find_delta_children(const union delta_base *base,
324                                int *first_index, int *last_index)
325 {
326         int first = find_delta(base);
327         int last = first;
328         int end = nr_deltas - 1;
329
330         if (first < 0)
331                 return -1;
332         while (first > 0 && !memcmp(&deltas[first - 1].base, base, UNION_BASE_SZ))
333                 --first;
334         while (last < end && !memcmp(&deltas[last + 1].base, base, UNION_BASE_SZ))
335                 ++last;
336         *first_index = first;
337         *last_index = last;
338         return 0;
339 }
340
341 static void sha1_object(const void *data, unsigned long size,
342                         enum object_type type, unsigned char *sha1)
343 {
344         SHA_CTX ctx;
345         char header[50];
346         int header_size;
347         const char *type_str;
348
349         switch (type) {
350         case OBJ_COMMIT: type_str = commit_type; break;
351         case OBJ_TREE:   type_str = tree_type; break;
352         case OBJ_BLOB:   type_str = blob_type; break;
353         case OBJ_TAG:    type_str = tag_type; break;
354         default:
355                 die("bad type %d", type);
356         }
357
358         header_size = sprintf(header, "%s %lu", type_str, size) + 1;
359
360         SHA1_Init(&ctx);
361         SHA1_Update(&ctx, header, header_size);
362         SHA1_Update(&ctx, data, size);
363         SHA1_Final(sha1, &ctx);
364 }
365
366 static void resolve_delta(struct object_entry *delta_obj, void *base_data,
367                           unsigned long base_size, enum object_type type)
368 {
369         void *delta_data;
370         unsigned long delta_size;
371         void *result;
372         unsigned long result_size;
373         union delta_base delta_base;
374         int j, first, last;
375
376         delta_obj->real_type = type;
377         delta_data = get_data_from_pack(delta_obj);
378         delta_size = delta_obj->size;
379         result = patch_delta(base_data, base_size, delta_data, delta_size,
380                              &result_size);
381         free(delta_data);
382         if (!result)
383                 bad_object(delta_obj->offset, "failed to apply delta");
384         sha1_object(result, result_size, type, delta_obj->sha1);
385         nr_resolved_deltas++;
386
387         hashcpy(delta_base.sha1, delta_obj->sha1);
388         if (!find_delta_children(&delta_base, &first, &last)) {
389                 for (j = first; j <= last; j++) {
390                         struct object_entry *child = objects + deltas[j].obj_no;
391                         if (child->real_type == OBJ_REF_DELTA)
392                                 resolve_delta(child, result, result_size, type);
393                 }
394         }
395
396         memset(&delta_base, 0, sizeof(delta_base));
397         delta_base.offset = delta_obj->offset;
398         if (!find_delta_children(&delta_base, &first, &last)) {
399                 for (j = first; j <= last; j++) {
400                         struct object_entry *child = objects + deltas[j].obj_no;
401                         if (child->real_type == OBJ_OFS_DELTA)
402                                 resolve_delta(child, result, result_size, type);
403                 }
404         }
405
406         free(result);
407 }
408
409 static int compare_delta_entry(const void *a, const void *b)
410 {
411         const struct delta_entry *delta_a = a;
412         const struct delta_entry *delta_b = b;
413         return memcmp(&delta_a->base, &delta_b->base, UNION_BASE_SZ);
414 }
415
416 /* Parse all objects and return the pack content SHA1 hash */
417 static void parse_pack_objects(unsigned char *sha1)
418 {
419         int i, percent = -1;
420         struct delta_entry *delta = deltas;
421         void *data;
422         struct stat st;
423
424         /*
425          * First pass:
426          * - find locations of all objects;
427          * - calculate SHA1 of all non-delta objects;
428          * - remember base (SHA1 or offset) for all deltas.
429          */
430         if (verbose)
431                 fprintf(stderr, "Indexing %d objects.\n", nr_objects);
432         for (i = 0; i < nr_objects; i++) {
433                 struct object_entry *obj = &objects[i];
434                 data = unpack_raw_entry(obj, &delta->base);
435                 obj->real_type = obj->type;
436                 if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
437                         nr_deltas++;
438                         delta->obj_no = i;
439                         delta++;
440                 } else
441                         sha1_object(data, obj->size, obj->type, obj->sha1);
442                 free(data);
443                 if (verbose)
444                         percent = display_progress(i+1, nr_objects, percent);
445         }
446         objects[i].offset = consumed_bytes;
447         if (verbose)
448                 fputc('\n', stderr);
449
450         /* Check pack integrity */
451         flush();
452         SHA1_Final(sha1, &input_ctx);
453         if (hashcmp(fill(20), sha1))
454                 die("pack is corrupted (SHA1 mismatch)");
455         use(20);
456
457         /* If input_fd is a file, we should have reached its end now. */
458         if (fstat(input_fd, &st))
459                 die("cannot fstat packfile: %s", strerror(errno));
460         if (S_ISREG(st.st_mode) && st.st_size != consumed_bytes)
461                 die("pack has junk at the end");
462
463         if (!nr_deltas)
464                 return;
465
466         /* Sort deltas by base SHA1/offset for fast searching */
467         qsort(deltas, nr_deltas, sizeof(struct delta_entry),
468               compare_delta_entry);
469
470         /*
471          * Second pass:
472          * - for all non-delta objects, look if it is used as a base for
473          *   deltas;
474          * - if used as a base, uncompress the object and apply all deltas,
475          *   recursively checking if the resulting object is used as a base
476          *   for some more deltas.
477          */
478         if (verbose)
479                 fprintf(stderr, "Resolving %d deltas.\n", nr_deltas);
480         for (i = 0; i < nr_objects; i++) {
481                 struct object_entry *obj = &objects[i];
482                 union delta_base base;
483                 int j, ref, ref_first, ref_last, ofs, ofs_first, ofs_last;
484
485                 if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
486                         continue;
487                 hashcpy(base.sha1, obj->sha1);
488                 ref = !find_delta_children(&base, &ref_first, &ref_last);
489                 memset(&base, 0, sizeof(base));
490                 base.offset = obj->offset;
491                 ofs = !find_delta_children(&base, &ofs_first, &ofs_last);
492                 if (!ref && !ofs)
493                         continue;
494                 data = get_data_from_pack(obj);
495                 if (ref)
496                         for (j = ref_first; j <= ref_last; j++) {
497                                 struct object_entry *child = objects + deltas[j].obj_no;
498                                 if (child->real_type == OBJ_REF_DELTA)
499                                         resolve_delta(child, data,
500                                                       obj->size, obj->type);
501                         }
502                 if (ofs)
503                         for (j = ofs_first; j <= ofs_last; j++) {
504                                 struct object_entry *child = objects + deltas[j].obj_no;
505                                 if (child->real_type == OBJ_OFS_DELTA)
506                                         resolve_delta(child, data,
507                                                       obj->size, obj->type);
508                         }
509                 free(data);
510                 if (verbose)
511                         percent = display_progress(nr_resolved_deltas,
512                                                    nr_deltas, percent);
513         }
514         if (verbose && nr_resolved_deltas == nr_deltas)
515                 fputc('\n', stderr);
516 }
517
518 static int write_compressed(int fd, void *in, unsigned int size)
519 {
520         z_stream stream;
521         unsigned long maxsize;
522         void *out;
523
524         memset(&stream, 0, sizeof(stream));
525         deflateInit(&stream, zlib_compression_level);
526         maxsize = deflateBound(&stream, size);
527         out = xmalloc(maxsize);
528
529         /* Compress it */
530         stream.next_in = in;
531         stream.avail_in = size;
532         stream.next_out = out;
533         stream.avail_out = maxsize;
534         while (deflate(&stream, Z_FINISH) == Z_OK);
535         deflateEnd(&stream);
536
537         size = stream.total_out;
538         write_or_die(fd, out, size);
539         free(out);
540         return size;
541 }
542
543 static void append_obj_to_pack(void *buf,
544                                unsigned long size, enum object_type type)
545 {
546         struct object_entry *obj = &objects[nr_objects++];
547         unsigned char header[10];
548         unsigned long s = size;
549         int n = 0;
550         unsigned char c = (type << 4) | (s & 15);
551         s >>= 4;
552         while (s) {
553                 header[n++] = c | 0x80;
554                 c = s & 0x7f;
555                 s >>= 7;
556         }
557         header[n++] = c;
558         write_or_die(output_fd, header, n);
559         obj[1].offset = obj[0].offset + n;
560         obj[1].offset += write_compressed(output_fd, buf, size);
561         sha1_object(buf, size, type, obj->sha1);
562 }
563
564 static int delta_pos_compare(const void *_a, const void *_b)
565 {
566         struct delta_entry *a = *(struct delta_entry **)_a;
567         struct delta_entry *b = *(struct delta_entry **)_b;
568         return a->obj_no - b->obj_no;
569 }
570
571 static void fix_unresolved_deltas(int nr_unresolved)
572 {
573         struct delta_entry **sorted_by_pos;
574         int i, n = 0, percent = -1;
575
576         /*
577          * Since many unresolved deltas may well be themselves base objects
578          * for more unresolved deltas, we really want to include the
579          * smallest number of base objects that would cover as much delta
580          * as possible by picking the
581          * trunc deltas first, allowing for other deltas to resolve without
582          * additional base objects.  Since most base objects are to be found
583          * before deltas depending on them, a good heuristic is to start
584          * resolving deltas in the same order as their position in the pack.
585          */
586         sorted_by_pos = xmalloc(nr_unresolved * sizeof(*sorted_by_pos));
587         for (i = 0; i < nr_deltas; i++) {
588                 if (objects[deltas[i].obj_no].real_type != OBJ_REF_DELTA)
589                         continue;
590                 sorted_by_pos[n++] = &deltas[i];
591         }
592         qsort(sorted_by_pos, n, sizeof(*sorted_by_pos), delta_pos_compare);
593
594         for (i = 0; i < n; i++) {
595                 struct delta_entry *d = sorted_by_pos[i];
596                 void *data;
597                 unsigned long size;
598                 char type[10];
599                 enum object_type obj_type;
600                 int j, first, last;
601
602                 if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
603                         continue;
604                 data = read_sha1_file(d->base.sha1, type, &size);
605                 if (!data)
606                         continue;
607                 if      (!strcmp(type, blob_type))   obj_type = OBJ_BLOB;
608                 else if (!strcmp(type, tree_type))   obj_type = OBJ_TREE;
609                 else if (!strcmp(type, commit_type)) obj_type = OBJ_COMMIT;
610                 else if (!strcmp(type, tag_type))    obj_type = OBJ_TAG;
611                 else die("base object %s is of type '%s'",
612                          sha1_to_hex(d->base.sha1), type);
613
614                 find_delta_children(&d->base, &first, &last);
615                 for (j = first; j <= last; j++) {
616                         struct object_entry *child = objects + deltas[j].obj_no;
617                         if (child->real_type == OBJ_REF_DELTA)
618                                 resolve_delta(child, data, size, obj_type);
619                 }
620
621                 append_obj_to_pack(data, size, obj_type);
622                 free(data);
623                 if (verbose)
624                         percent = display_progress(nr_resolved_deltas,
625                                                    nr_deltas, percent);
626         }
627         free(sorted_by_pos);
628         if (verbose)
629                 fputc('\n', stderr);
630 }
631
632 static void readjust_pack_header_and_sha1(unsigned char *sha1)
633 {
634         struct pack_header hdr;
635         SHA_CTX ctx;
636         int size;
637
638         /* Rewrite pack header with updated object number */
639         if (lseek(output_fd, 0, SEEK_SET) != 0)
640                 die("cannot seek back: %s", strerror(errno));
641         if (xread(output_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
642                 die("cannot read pack header back: %s", strerror(errno));
643         hdr.hdr_entries = htonl(nr_objects);
644         if (lseek(output_fd, 0, SEEK_SET) != 0)
645                 die("cannot seek back: %s", strerror(errno));
646         write_or_die(output_fd, &hdr, sizeof(hdr));
647         if (lseek(output_fd, 0, SEEK_SET) != 0)
648                 die("cannot seek back: %s", strerror(errno));
649
650         /* Recompute and store the new pack's SHA1 */
651         SHA1_Init(&ctx);
652         do {
653                 unsigned char *buf[4096];
654                 size = xread(output_fd, buf, sizeof(buf));
655                 if (size < 0)
656                         die("cannot read pack data back: %s", strerror(errno));
657                 SHA1_Update(&ctx, buf, size);
658         } while (size > 0);
659         SHA1_Final(sha1, &ctx);
660         write_or_die(output_fd, sha1, 20);
661 }
662
663 static int sha1_compare(const void *_a, const void *_b)
664 {
665         struct object_entry *a = *(struct object_entry **)_a;
666         struct object_entry *b = *(struct object_entry **)_b;
667         return hashcmp(a->sha1, b->sha1);
668 }
669
670 /*
671  * On entry *sha1 contains the pack content SHA1 hash, on exit it is
672  * the SHA1 hash of sorted object names.
673  */
674 static const char *write_index_file(const char *index_name, unsigned char *sha1)
675 {
676         struct sha1file *f;
677         struct object_entry **sorted_by_sha, **list, **last;
678         unsigned int array[256];
679         int i, fd;
680         SHA_CTX ctx;
681
682         if (nr_objects) {
683                 sorted_by_sha =
684                         xcalloc(nr_objects, sizeof(struct object_entry *));
685                 list = sorted_by_sha;
686                 last = sorted_by_sha + nr_objects;
687                 for (i = 0; i < nr_objects; ++i)
688                         sorted_by_sha[i] = &objects[i];
689                 qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
690                       sha1_compare);
691
692         }
693         else
694                 sorted_by_sha = list = last = NULL;
695
696         if (!index_name) {
697                 static char tmpfile[PATH_MAX];
698                 snprintf(tmpfile, sizeof(tmpfile),
699                          "%s/index_XXXXXX", get_object_directory());
700                 fd = mkstemp(tmpfile);
701                 index_name = xstrdup(tmpfile);
702         } else {
703                 unlink(index_name);
704                 fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
705         }
706         if (fd < 0)
707                 die("unable to create %s: %s", index_name, strerror(errno));
708         f = sha1fd(fd, index_name);
709
710         /*
711          * Write the first-level table (the list is sorted,
712          * but we use a 256-entry lookup to be able to avoid
713          * having to do eight extra binary search iterations).
714          */
715         for (i = 0; i < 256; i++) {
716                 struct object_entry **next = list;
717                 while (next < last) {
718                         struct object_entry *obj = *next;
719                         if (obj->sha1[0] != i)
720                                 break;
721                         next++;
722                 }
723                 array[i] = htonl(next - sorted_by_sha);
724                 list = next;
725         }
726         sha1write(f, array, 256 * sizeof(int));
727
728         /* recompute the SHA1 hash of sorted object names.
729          * currently pack-objects does not do this, but that
730          * can be fixed.
731          */
732         SHA1_Init(&ctx);
733         /*
734          * Write the actual SHA1 entries..
735          */
736         list = sorted_by_sha;
737         for (i = 0; i < nr_objects; i++) {
738                 struct object_entry *obj = *list++;
739                 unsigned int offset = htonl(obj->offset);
740                 sha1write(f, &offset, 4);
741                 sha1write(f, obj->sha1, 20);
742                 SHA1_Update(&ctx, obj->sha1, 20);
743         }
744         sha1write(f, sha1, 20);
745         sha1close(f, NULL, 1);
746         free(sorted_by_sha);
747         SHA1_Final(sha1, &ctx);
748         return index_name;
749 }
750
751 static void final(const char *final_pack_name, const char *curr_pack_name,
752                   const char *final_index_name, const char *curr_index_name,
753                   const char *keep_name, const char *keep_msg,
754                   unsigned char *sha1)
755 {
756         char *report = "pack";
757         char name[PATH_MAX];
758         int err;
759
760         if (!from_stdin) {
761                 close(input_fd);
762         } else {
763                 err = close(output_fd);
764                 if (err)
765                         die("error while closing pack file: %s", strerror(errno));
766                 chmod(curr_pack_name, 0444);
767         }
768
769         if (keep_msg) {
770                 int keep_fd, keep_msg_len = strlen(keep_msg);
771                 if (!keep_name) {
772                         snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
773                                  get_object_directory(), sha1_to_hex(sha1));
774                         keep_name = name;
775                 }
776                 keep_fd = open(keep_name, O_RDWR|O_CREAT|O_EXCL, 0600);
777                 if (keep_fd < 0) {
778                         if (errno != EEXIST)
779                                 die("cannot write keep file");
780                 } else {
781                         if (keep_msg_len > 0) {
782                                 write_or_die(keep_fd, keep_msg, keep_msg_len);
783                                 write_or_die(keep_fd, "\n", 1);
784                         }
785                         close(keep_fd);
786                         report = "keep";
787                 }
788         }
789
790         if (final_pack_name != curr_pack_name) {
791                 if (!final_pack_name) {
792                         snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
793                                  get_object_directory(), sha1_to_hex(sha1));
794                         final_pack_name = name;
795                 }
796                 if (move_temp_to_file(curr_pack_name, final_pack_name))
797                         die("cannot store pack file");
798         }
799
800         chmod(curr_index_name, 0444);
801         if (final_index_name != curr_index_name) {
802                 if (!final_index_name) {
803                         snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
804                                  get_object_directory(), sha1_to_hex(sha1));
805                         final_index_name = name;
806                 }
807                 if (move_temp_to_file(curr_index_name, final_index_name))
808                         die("cannot store index file");
809         }
810
811         if (!from_stdin) {
812                 printf("%s\n", sha1_to_hex(sha1));
813         } else {
814                 char buf[48];
815                 int len = snprintf(buf, sizeof(buf), "%s\t%s\n",
816                                    report, sha1_to_hex(sha1));
817                 xwrite(1, buf, len);
818
819                 /*
820                  * Let's just mimic git-unpack-objects here and write
821                  * the last part of the input buffer to stdout.
822                  */
823                 while (input_len) {
824                         err = xwrite(1, input_buffer + input_offset, input_len);
825                         if (err <= 0)
826                                 break;
827                         input_len -= err;
828                         input_offset += err;
829                 }
830         }
831 }
832
833 int main(int argc, char **argv)
834 {
835         int i, fix_thin_pack = 0;
836         const char *curr_pack, *pack_name = NULL;
837         const char *curr_index, *index_name = NULL;
838         const char *keep_name = NULL, *keep_msg = NULL;
839         char *index_name_buf = NULL, *keep_name_buf = NULL;
840         unsigned char sha1[20];
841
842         for (i = 1; i < argc; i++) {
843                 const char *arg = argv[i];
844
845                 if (*arg == '-') {
846                         if (!strcmp(arg, "--stdin")) {
847                                 from_stdin = 1;
848                         } else if (!strcmp(arg, "--fix-thin")) {
849                                 fix_thin_pack = 1;
850                         } else if (!strcmp(arg, "--keep")) {
851                                 keep_msg = "";
852                         } else if (!strncmp(arg, "--keep=", 7)) {
853                                 keep_msg = arg + 7;
854                         } else if (!strncmp(arg, "--pack_header=", 14)) {
855                                 struct pack_header *hdr;
856                                 char *c;
857
858                                 hdr = (struct pack_header *)input_buffer;
859                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
860                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
861                                 if (*c != ',')
862                                         die("bad %s", arg);
863                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
864                                 if (*c)
865                                         die("bad %s", arg);
866                                 input_len = sizeof(*hdr);
867                         } else if (!strcmp(arg, "-v")) {
868                                 verbose = 1;
869                         } else if (!strcmp(arg, "-o")) {
870                                 if (index_name || (i+1) >= argc)
871                                         usage(index_pack_usage);
872                                 index_name = argv[++i];
873                         } else
874                                 usage(index_pack_usage);
875                         continue;
876                 }
877
878                 if (pack_name)
879                         usage(index_pack_usage);
880                 pack_name = arg;
881         }
882
883         if (!pack_name && !from_stdin)
884                 usage(index_pack_usage);
885         if (fix_thin_pack && !from_stdin)
886                 die("--fix-thin cannot be used without --stdin");
887         if (!index_name && pack_name) {
888                 int len = strlen(pack_name);
889                 if (!has_extension(pack_name, ".pack"))
890                         die("packfile name '%s' does not end with '.pack'",
891                             pack_name);
892                 index_name_buf = xmalloc(len);
893                 memcpy(index_name_buf, pack_name, len - 5);
894                 strcpy(index_name_buf + len - 5, ".idx");
895                 index_name = index_name_buf;
896         }
897         if (keep_msg && !keep_name && pack_name) {
898                 int len = strlen(pack_name);
899                 if (!has_extension(pack_name, ".pack"))
900                         die("packfile name '%s' does not end with '.pack'",
901                             pack_name);
902                 keep_name_buf = xmalloc(len);
903                 memcpy(keep_name_buf, pack_name, len - 5);
904                 strcpy(keep_name_buf + len - 5, ".keep");
905                 keep_name = keep_name_buf;
906         }
907
908         curr_pack = open_pack_file(pack_name);
909         parse_pack_header();
910         objects = xmalloc((nr_objects + 1) * sizeof(struct object_entry));
911         deltas = xmalloc(nr_objects * sizeof(struct delta_entry));
912         if (verbose)
913                 setup_progress_signal();
914         parse_pack_objects(sha1);
915         if (nr_deltas != nr_resolved_deltas) {
916                 if (fix_thin_pack) {
917                         int nr_unresolved = nr_deltas - nr_resolved_deltas;
918                         int nr_objects_initial = nr_objects;
919                         if (nr_unresolved <= 0)
920                                 die("confusion beyond insanity");
921                         objects = xrealloc(objects,
922                                            (nr_objects + nr_unresolved + 1)
923                                            * sizeof(*objects));
924                         fix_unresolved_deltas(nr_unresolved);
925                         if (verbose)
926                                 fprintf(stderr, "%d objects were added to complete this thin pack.\n",
927                                         nr_objects - nr_objects_initial);
928                         readjust_pack_header_and_sha1(sha1);
929                 }
930                 if (nr_deltas != nr_resolved_deltas)
931                         die("pack has %d unresolved deltas",
932                             nr_deltas - nr_resolved_deltas);
933         } else {
934                 /* Flush remaining pack final 20-byte SHA1. */
935                 flush();
936         }
937         free(deltas);
938         curr_index = write_index_file(index_name, sha1);
939         final(pack_name, curr_pack,
940                 index_name, curr_index,
941                 keep_name, keep_msg,
942                 sha1);
943         free(objects);
944         free(index_name_buf);
945         free(keep_name_buf);
946
947         return 0;
948 }