Merge branch 'ak/doc-add-v-n-options'
[git] / builtin / unpack-objects.c
1 #include "builtin.h"
2 #include "cache.h"
3 #include "object.h"
4 #include "delta.h"
5 #include "pack.h"
6 #include "blob.h"
7 #include "commit.h"
8 #include "tag.h"
9 #include "tree.h"
10 #include "tree-walk.h"
11 #include "progress.h"
12 #include "decorate.h"
13 #include "fsck.h"
14
15 static int dry_run, quiet, recover, has_errors, strict;
16 static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict] < pack-file";
17
18 /* We always read in 4kB chunks. */
19 static unsigned char buffer[4096];
20 static unsigned int offset, len;
21 static off_t consumed_bytes;
22 static git_SHA_CTX ctx;
23
24 /*
25  * When running under --strict mode, objects whose reachability are
26  * suspect are kept in core without getting written in the object
27  * store.
28  */
29 struct obj_buffer {
30         char *buffer;
31         unsigned long size;
32 };
33
34 static struct decoration obj_decorate;
35
36 static struct obj_buffer *lookup_object_buffer(struct object *base)
37 {
38         return lookup_decoration(&obj_decorate, base);
39 }
40
41 static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
42 {
43         struct obj_buffer *obj;
44         obj = xcalloc(1, sizeof(struct obj_buffer));
45         obj->buffer = buffer;
46         obj->size = size;
47         if (add_decoration(&obj_decorate, object, obj))
48                 die("object %s tried to add buffer twice!", sha1_to_hex(object->sha1));
49 }
50
51 /*
52  * Make sure at least "min" bytes are available in the buffer, and
53  * return the pointer to the buffer.
54  */
55 static void *fill(int min)
56 {
57         if (min <= len)
58                 return buffer + offset;
59         if (min > sizeof(buffer))
60                 die("cannot fill %d bytes", min);
61         if (offset) {
62                 git_SHA1_Update(&ctx, buffer, offset);
63                 memmove(buffer, buffer + offset, len);
64                 offset = 0;
65         }
66         do {
67                 ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
68                 if (ret <= 0) {
69                         if (!ret)
70                                 die("early EOF");
71                         die_errno("read error on input");
72                 }
73                 len += ret;
74         } while (len < min);
75         return buffer;
76 }
77
78 static void use(int bytes)
79 {
80         if (bytes > len)
81                 die("used more bytes than were available");
82         len -= bytes;
83         offset += bytes;
84
85         /* make sure off_t is sufficiently large not to wrap */
86         if (signed_add_overflows(consumed_bytes, bytes))
87                 die("pack too large for current definition of off_t");
88         consumed_bytes += bytes;
89 }
90
91 static void *get_data(unsigned long size)
92 {
93         git_zstream stream;
94         void *buf = xmallocz(size);
95
96         memset(&stream, 0, sizeof(stream));
97
98         stream.next_out = buf;
99         stream.avail_out = size;
100         stream.next_in = fill(1);
101         stream.avail_in = len;
102         git_inflate_init(&stream);
103
104         for (;;) {
105                 int ret = git_inflate(&stream, 0);
106                 use(len - stream.avail_in);
107                 if (stream.total_out == size && ret == Z_STREAM_END)
108                         break;
109                 if (ret != Z_OK) {
110                         error("inflate returned %d", ret);
111                         free(buf);
112                         buf = NULL;
113                         if (!recover)
114                                 exit(1);
115                         has_errors = 1;
116                         break;
117                 }
118                 stream.next_in = fill(1);
119                 stream.avail_in = len;
120         }
121         git_inflate_end(&stream);
122         return buf;
123 }
124
125 struct delta_info {
126         unsigned char base_sha1[20];
127         unsigned nr;
128         off_t base_offset;
129         unsigned long size;
130         void *delta;
131         struct delta_info *next;
132 };
133
134 static struct delta_info *delta_list;
135
136 static void add_delta_to_list(unsigned nr, unsigned const char *base_sha1,
137                               off_t base_offset,
138                               void *delta, unsigned long size)
139 {
140         struct delta_info *info = xmalloc(sizeof(*info));
141
142         hashcpy(info->base_sha1, base_sha1);
143         info->base_offset = base_offset;
144         info->size = size;
145         info->delta = delta;
146         info->nr = nr;
147         info->next = delta_list;
148         delta_list = info;
149 }
150
151 struct obj_info {
152         off_t offset;
153         unsigned char sha1[20];
154         struct object *obj;
155 };
156
157 #define FLAG_OPEN (1u<<20)
158 #define FLAG_WRITTEN (1u<<21)
159
160 static struct obj_info *obj_list;
161 static unsigned nr_objects;
162
163 /*
164  * Called only from check_object() after it verified this object
165  * is Ok.
166  */
167 static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
168 {
169         unsigned char sha1[20];
170
171         if (write_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), sha1) < 0)
172                 die("failed to write object %s", sha1_to_hex(obj->sha1));
173         obj->flags |= FLAG_WRITTEN;
174 }
175
176 /*
177  * At the very end of the processing, write_rest() scans the objects
178  * that have reachability requirements and calls this function.
179  * Verify its reachability and validity recursively and write it out.
180  */
181 static int check_object(struct object *obj, int type, void *data)
182 {
183         struct obj_buffer *obj_buf;
184
185         if (!obj)
186                 return 1;
187
188         if (obj->flags & FLAG_WRITTEN)
189                 return 0;
190
191         if (type != OBJ_ANY && obj->type != type)
192                 die("object type mismatch");
193
194         if (!(obj->flags & FLAG_OPEN)) {
195                 unsigned long size;
196                 int type = sha1_object_info(obj->sha1, &size);
197                 if (type != obj->type || type <= 0)
198                         die("object of unexpected type");
199                 obj->flags |= FLAG_WRITTEN;
200                 return 0;
201         }
202
203         obj_buf = lookup_object_buffer(obj);
204         if (!obj_buf)
205                 die("Whoops! Cannot find object '%s'", sha1_to_hex(obj->sha1));
206         if (fsck_object(obj, obj_buf->buffer, obj_buf->size, 1,
207                         fsck_error_function))
208                 die("Error in object");
209         if (fsck_walk(obj, check_object, NULL))
210                 die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
211         write_cached_object(obj, obj_buf);
212         return 0;
213 }
214
215 static void write_rest(void)
216 {
217         unsigned i;
218         for (i = 0; i < nr_objects; i++) {
219                 if (obj_list[i].obj)
220                         check_object(obj_list[i].obj, OBJ_ANY, NULL);
221         }
222 }
223
224 static void added_object(unsigned nr, enum object_type type,
225                          void *data, unsigned long size);
226
227 /*
228  * Write out nr-th object from the list, now we know the contents
229  * of it.  Under --strict, this buffers structured objects in-core,
230  * to be checked at the end.
231  */
232 static void write_object(unsigned nr, enum object_type type,
233                          void *buf, unsigned long size)
234 {
235         if (!strict) {
236                 if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
237                         die("failed to write object");
238                 added_object(nr, type, buf, size);
239                 free(buf);
240                 obj_list[nr].obj = NULL;
241         } else if (type == OBJ_BLOB) {
242                 struct blob *blob;
243                 if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
244                         die("failed to write object");
245                 added_object(nr, type, buf, size);
246                 free(buf);
247
248                 blob = lookup_blob(obj_list[nr].sha1);
249                 if (blob)
250                         blob->object.flags |= FLAG_WRITTEN;
251                 else
252                         die("invalid blob object");
253                 obj_list[nr].obj = NULL;
254         } else {
255                 struct object *obj;
256                 int eaten;
257                 hash_sha1_file(buf, size, typename(type), obj_list[nr].sha1);
258                 added_object(nr, type, buf, size);
259                 obj = parse_object_buffer(obj_list[nr].sha1, type, size, buf, &eaten);
260                 if (!obj)
261                         die("invalid %s", typename(type));
262                 add_object_buffer(obj, buf, size);
263                 obj->flags |= FLAG_OPEN;
264                 obj_list[nr].obj = obj;
265         }
266 }
267
268 static void resolve_delta(unsigned nr, enum object_type type,
269                           void *base, unsigned long base_size,
270                           void *delta, unsigned long delta_size)
271 {
272         void *result;
273         unsigned long result_size;
274
275         result = patch_delta(base, base_size,
276                              delta, delta_size,
277                              &result_size);
278         if (!result)
279                 die("failed to apply delta");
280         free(delta);
281         write_object(nr, type, result, result_size);
282 }
283
284 /*
285  * We now know the contents of an object (which is nr-th in the pack);
286  * resolve all the deltified objects that are based on it.
287  */
288 static void added_object(unsigned nr, enum object_type type,
289                          void *data, unsigned long size)
290 {
291         struct delta_info **p = &delta_list;
292         struct delta_info *info;
293
294         while ((info = *p) != NULL) {
295                 if (!hashcmp(info->base_sha1, obj_list[nr].sha1) ||
296                     info->base_offset == obj_list[nr].offset) {
297                         *p = info->next;
298                         p = &delta_list;
299                         resolve_delta(info->nr, type, data, size,
300                                       info->delta, info->size);
301                         free(info);
302                         continue;
303                 }
304                 p = &info->next;
305         }
306 }
307
308 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
309                                    unsigned nr)
310 {
311         void *buf = get_data(size);
312
313         if (!dry_run && buf)
314                 write_object(nr, type, buf, size);
315         else
316                 free(buf);
317 }
318
319 static int resolve_against_held(unsigned nr, const unsigned char *base,
320                                 void *delta_data, unsigned long delta_size)
321 {
322         struct object *obj;
323         struct obj_buffer *obj_buffer;
324         obj = lookup_object(base);
325         if (!obj)
326                 return 0;
327         obj_buffer = lookup_object_buffer(obj);
328         if (!obj_buffer)
329                 return 0;
330         resolve_delta(nr, obj->type, obj_buffer->buffer,
331                       obj_buffer->size, delta_data, delta_size);
332         return 1;
333 }
334
335 static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
336                                unsigned nr)
337 {
338         void *delta_data, *base;
339         unsigned long base_size;
340         unsigned char base_sha1[20];
341
342         if (type == OBJ_REF_DELTA) {
343                 hashcpy(base_sha1, fill(20));
344                 use(20);
345                 delta_data = get_data(delta_size);
346                 if (dry_run || !delta_data) {
347                         free(delta_data);
348                         return;
349                 }
350                 if (has_sha1_file(base_sha1))
351                         ; /* Ok we have this one */
352                 else if (resolve_against_held(nr, base_sha1,
353                                               delta_data, delta_size))
354                         return; /* we are done */
355                 else {
356                         /* cannot resolve yet --- queue it */
357                         hashcpy(obj_list[nr].sha1, null_sha1);
358                         add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
359                         return;
360                 }
361         } else {
362                 unsigned base_found = 0;
363                 unsigned char *pack, c;
364                 off_t base_offset;
365                 unsigned lo, mid, hi;
366
367                 pack = fill(1);
368                 c = *pack;
369                 use(1);
370                 base_offset = c & 127;
371                 while (c & 128) {
372                         base_offset += 1;
373                         if (!base_offset || MSB(base_offset, 7))
374                                 die("offset value overflow for delta base object");
375                         pack = fill(1);
376                         c = *pack;
377                         use(1);
378                         base_offset = (base_offset << 7) + (c & 127);
379                 }
380                 base_offset = obj_list[nr].offset - base_offset;
381                 if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
382                         die("offset value out of bound for delta base object");
383
384                 delta_data = get_data(delta_size);
385                 if (dry_run || !delta_data) {
386                         free(delta_data);
387                         return;
388                 }
389                 lo = 0;
390                 hi = nr;
391                 while (lo < hi) {
392                         mid = (lo + hi)/2;
393                         if (base_offset < obj_list[mid].offset) {
394                                 hi = mid;
395                         } else if (base_offset > obj_list[mid].offset) {
396                                 lo = mid + 1;
397                         } else {
398                                 hashcpy(base_sha1, obj_list[mid].sha1);
399                                 base_found = !is_null_sha1(base_sha1);
400                                 break;
401                         }
402                 }
403                 if (!base_found) {
404                         /*
405                          * The delta base object is itself a delta that
406                          * has not been resolved yet.
407                          */
408                         hashcpy(obj_list[nr].sha1, null_sha1);
409                         add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
410                         return;
411                 }
412         }
413
414         if (resolve_against_held(nr, base_sha1, delta_data, delta_size))
415                 return;
416
417         base = read_sha1_file(base_sha1, &type, &base_size);
418         if (!base) {
419                 error("failed to read delta-pack base object %s",
420                       sha1_to_hex(base_sha1));
421                 if (!recover)
422                         exit(1);
423                 has_errors = 1;
424                 return;
425         }
426         resolve_delta(nr, type, base, base_size, delta_data, delta_size);
427         free(base);
428 }
429
430 static void unpack_one(unsigned nr)
431 {
432         unsigned shift;
433         unsigned char *pack;
434         unsigned long size, c;
435         enum object_type type;
436
437         obj_list[nr].offset = consumed_bytes;
438
439         pack = fill(1);
440         c = *pack;
441         use(1);
442         type = (c >> 4) & 7;
443         size = (c & 15);
444         shift = 4;
445         while (c & 0x80) {
446                 pack = fill(1);
447                 c = *pack;
448                 use(1);
449                 size += (c & 0x7f) << shift;
450                 shift += 7;
451         }
452
453         switch (type) {
454         case OBJ_COMMIT:
455         case OBJ_TREE:
456         case OBJ_BLOB:
457         case OBJ_TAG:
458                 unpack_non_delta_entry(type, size, nr);
459                 return;
460         case OBJ_REF_DELTA:
461         case OBJ_OFS_DELTA:
462                 unpack_delta_entry(type, size, nr);
463                 return;
464         default:
465                 error("bad object type %d", type);
466                 has_errors = 1;
467                 if (recover)
468                         return;
469                 exit(1);
470         }
471 }
472
473 static void unpack_all(void)
474 {
475         int i;
476         struct progress *progress = NULL;
477         struct pack_header *hdr = fill(sizeof(struct pack_header));
478
479         nr_objects = ntohl(hdr->hdr_entries);
480
481         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
482                 die("bad pack file");
483         if (!pack_version_ok(hdr->hdr_version))
484                 die("unknown pack file version %"PRIu32,
485                         ntohl(hdr->hdr_version));
486         use(sizeof(struct pack_header));
487
488         if (!quiet)
489                 progress = start_progress(_("Unpacking objects"), nr_objects);
490         obj_list = xcalloc(nr_objects, sizeof(*obj_list));
491         for (i = 0; i < nr_objects; i++) {
492                 unpack_one(i);
493                 display_progress(progress, i + 1);
494         }
495         stop_progress(&progress);
496
497         if (delta_list)
498                 die("unresolved deltas left after unpacking");
499 }
500
501 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
502 {
503         int i;
504         unsigned char sha1[20];
505
506         check_replace_refs = 0;
507
508         git_config(git_default_config, NULL);
509
510         quiet = !isatty(2);
511
512         for (i = 1 ; i < argc; i++) {
513                 const char *arg = argv[i];
514
515                 if (*arg == '-') {
516                         if (!strcmp(arg, "-n")) {
517                                 dry_run = 1;
518                                 continue;
519                         }
520                         if (!strcmp(arg, "-q")) {
521                                 quiet = 1;
522                                 continue;
523                         }
524                         if (!strcmp(arg, "-r")) {
525                                 recover = 1;
526                                 continue;
527                         }
528                         if (!strcmp(arg, "--strict")) {
529                                 strict = 1;
530                                 continue;
531                         }
532                         if (starts_with(arg, "--pack_header=")) {
533                                 struct pack_header *hdr;
534                                 char *c;
535
536                                 hdr = (struct pack_header *)buffer;
537                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
538                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
539                                 if (*c != ',')
540                                         die("bad %s", arg);
541                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
542                                 if (*c)
543                                         die("bad %s", arg);
544                                 len = sizeof(*hdr);
545                                 continue;
546                         }
547                         usage(unpack_usage);
548                 }
549
550                 /* We don't take any non-flag arguments now.. Maybe some day */
551                 usage(unpack_usage);
552         }
553         git_SHA1_Init(&ctx);
554         unpack_all();
555         git_SHA1_Update(&ctx, buffer, offset);
556         git_SHA1_Final(sha1, &ctx);
557         if (strict)
558                 write_rest();
559         if (hashcmp(fill(20), sha1))
560                 die("final sha1 did not match");
561         use(20);
562
563         /* Write the last part of the buffer to stdout */
564         while (len) {
565                 int ret = xwrite(1, buffer + offset, len);
566                 if (ret <= 0)
567                         break;
568                 len -= ret;
569                 offset += ret;
570         }
571
572         /* All done */
573         return has_errors;
574 }