Make git rebase interactive help match documentation.
[git.git] / pack-objects.c
1 #include "cache.h"
2 #include "object.h"
3 #include "blob.h"
4 #include "commit.h"
5 #include "tag.h"
6 #include "tree.h"
7 #include "delta.h"
8 #include "pack.h"
9 #include "csum-file.h"
10 #include "tree-walk.h"
11 #include <sys/time.h>
12 #include <signal.h>
13 #include <stdint.h>
14
15 static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
16
17 struct object_entry {
18         unsigned char sha1[20];
19         unsigned long size;     /* uncompressed size */
20         unsigned long offset;   /* offset into the final pack file;
21                                  * nonzero if already written.
22                                  */
23         unsigned int depth;     /* delta depth */
24         unsigned int delta_limit;       /* base adjustment for in-pack delta */
25         unsigned int hash;      /* name hint hash */
26         enum object_type type;
27         enum object_type in_pack_type;  /* could be delta */
28         unsigned long delta_size;       /* delta data size (uncompressed) */
29         struct object_entry *delta;     /* delta base object */
30         struct packed_git *in_pack;     /* already in pack */
31         unsigned int in_pack_offset;
32         struct object_entry *delta_child; /* delitified objects who bases me */
33         struct object_entry *delta_sibling; /* other deltified objects who
34                                              * uses the same base as me
35                                              */
36         int preferred_base;     /* we do not pack this, but is encouraged to
37                                  * be used as the base objectto delta huge
38                                  * objects against.
39                                  */
40 };
41
42 /*
43  * Objects we are going to pack are colected in objects array (dynamically
44  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
45  * in the order we see -- typically rev-list --objects order that gives us
46  * nice "minimum seek" order.
47  *
48  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
49  * elements in the objects array.  The former is used to build the pack
50  * index (lists object names in the ascending order to help offset lookup),
51  * and the latter is used to group similar things together by try_delta()
52  * heuristics.
53  */
54
55 static unsigned char object_list_sha1[20];
56 static int non_empty = 0;
57 static int no_reuse_delta = 0;
58 static int local = 0;
59 static int incremental = 0;
60 static struct object_entry **sorted_by_sha, **sorted_by_type;
61 static struct object_entry *objects = NULL;
62 static int nr_objects = 0, nr_alloc = 0, nr_result = 0;
63 static const char *base_name;
64 static unsigned char pack_file_sha1[20];
65 static int progress = 1;
66 static volatile sig_atomic_t progress_update = 0;
67
68 /*
69  * The object names in objects array are hashed with this hashtable,
70  * to help looking up the entry by object name.  Binary search from
71  * sorted_by_sha is also possible but this was easier to code and faster.
72  * This hashtable is built after all the objects are seen.
73  */
74 static int *object_ix = NULL;
75 static int object_ix_hashsz = 0;
76
77 /*
78  * Pack index for existing packs give us easy access to the offsets into
79  * corresponding pack file where each object's data starts, but the entries
80  * do not store the size of the compressed representation (uncompressed
81  * size is easily available by examining the pack entry header).  We build
82  * a hashtable of existing packs (pack_revindex), and keep reverse index
83  * here -- pack index file is sorted by object name mapping to offset; this
84  * pack_revindex[].revindex array is an ordered list of offsets, so if you
85  * know the offset of an object, next offset is where its packed
86  * representation ends.
87  */
88 struct pack_revindex {
89         struct packed_git *p;
90         unsigned long *revindex;
91 } *pack_revindex = NULL;
92 static int pack_revindex_hashsz = 0;
93
94 /*
95  * stats
96  */
97 static int written = 0;
98 static int written_delta = 0;
99 static int reused = 0;
100 static int reused_delta = 0;
101
102 static int pack_revindex_ix(struct packed_git *p)
103 {
104         unsigned long ui = (unsigned long)p;
105         int i;
106
107         ui = ui ^ (ui >> 16); /* defeat structure alignment */
108         i = (int)(ui % pack_revindex_hashsz);
109         while (pack_revindex[i].p) {
110                 if (pack_revindex[i].p == p)
111                         return i;
112                 if (++i == pack_revindex_hashsz)
113                         i = 0;
114         }
115         return -1 - i;
116 }
117
118 static void prepare_pack_ix(void)
119 {
120         int num;
121         struct packed_git *p;
122         for (num = 0, p = packed_git; p; p = p->next)
123                 num++;
124         if (!num)
125                 return;
126         pack_revindex_hashsz = num * 11;
127         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
128         for (p = packed_git; p; p = p->next) {
129                 num = pack_revindex_ix(p);
130                 num = - 1 - num;
131                 pack_revindex[num].p = p;
132         }
133         /* revindex elements are lazily initialized */
134 }
135
136 static int cmp_offset(const void *a_, const void *b_)
137 {
138         unsigned long a = *(unsigned long *) a_;
139         unsigned long b = *(unsigned long *) b_;
140         if (a < b)
141                 return -1;
142         else if (a == b)
143                 return 0;
144         else
145                 return 1;
146 }
147
148 /*
149  * Ordered list of offsets of objects in the pack.
150  */
151 static void prepare_pack_revindex(struct pack_revindex *rix)
152 {
153         struct packed_git *p = rix->p;
154         int num_ent = num_packed_objects(p);
155         int i;
156         void *index = p->index_base + 256;
157
158         rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
159         for (i = 0; i < num_ent; i++) {
160                 uint32_t hl = *((uint32_t *)(index + 24 * i));
161                 rix->revindex[i] = ntohl(hl);
162         }
163         /* This knows the pack format -- the 20-byte trailer
164          * follows immediately after the last object data.
165          */
166         rix->revindex[num_ent] = p->pack_size - 20;
167         qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
168 }
169
170 static unsigned long find_packed_object_size(struct packed_git *p,
171                                              unsigned long ofs)
172 {
173         int num;
174         int lo, hi;
175         struct pack_revindex *rix;
176         unsigned long *revindex;
177         num = pack_revindex_ix(p);
178         if (num < 0)
179                 die("internal error: pack revindex uninitialized");
180         rix = &pack_revindex[num];
181         if (!rix->revindex)
182                 prepare_pack_revindex(rix);
183         revindex = rix->revindex;
184         lo = 0;
185         hi = num_packed_objects(p) + 1;
186         do {
187                 int mi = (lo + hi) / 2;
188                 if (revindex[mi] == ofs) {
189                         return revindex[mi+1] - ofs;
190                 }
191                 else if (ofs < revindex[mi])
192                         hi = mi;
193                 else
194                         lo = mi + 1;
195         } while (lo < hi);
196         die("internal error: pack revindex corrupt");
197 }
198
199 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
200 {
201         unsigned long othersize, delta_size;
202         char type[10];
203         void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
204         void *delta_buf;
205
206         if (!otherbuf)
207                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
208         delta_buf = diff_delta(otherbuf, othersize,
209                                buf, size, &delta_size, 0);
210         if (!delta_buf || delta_size != entry->delta_size)
211                 die("delta size changed");
212         free(buf);
213         free(otherbuf);
214         return delta_buf;
215 }
216
217 /*
218  * The per-object header is a pretty dense thing, which is
219  *  - first byte: low four bits are "size", then three bits of "type",
220  *    and the high bit is "size continues".
221  *  - each byte afterwards: low seven bits are size continuation,
222  *    with the high bit being "size continues"
223  */
224 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
225 {
226         int n = 1;
227         unsigned char c;
228
229         if (type < OBJ_COMMIT || type > OBJ_DELTA)
230                 die("bad type %d", type);
231
232         c = (type << 4) | (size & 15);
233         size >>= 4;
234         while (size) {
235                 *hdr++ = c | 0x80;
236                 c = size & 0x7f;
237                 size >>= 7;
238                 n++;
239         }
240         *hdr = c;
241         return n;
242 }
243
244 static unsigned long write_object(struct sha1file *f,
245                                   struct object_entry *entry)
246 {
247         unsigned long size;
248         char type[10];
249         void *buf;
250         unsigned char header[10];
251         unsigned hdrlen, datalen;
252         enum object_type obj_type;
253         int to_reuse = 0;
254
255         if (entry->preferred_base)
256                 return 0;
257
258         obj_type = entry->type;
259         if (! entry->in_pack)
260                 to_reuse = 0;   /* can't reuse what we don't have */
261         else if (obj_type == OBJ_DELTA)
262                 to_reuse = 1;   /* check_object() decided it for us */
263         else if (obj_type != entry->in_pack_type)
264                 to_reuse = 0;   /* pack has delta which is unusable */
265         else if (entry->delta)
266                 to_reuse = 0;   /* we want to pack afresh */
267         else
268                 to_reuse = 1;   /* we have it in-pack undeltified,
269                                  * and we do not need to deltify it.
270                                  */
271
272         if (! to_reuse) {
273                 buf = read_sha1_file(entry->sha1, type, &size);
274                 if (!buf)
275                         die("unable to read %s", sha1_to_hex(entry->sha1));
276                 if (size != entry->size)
277                         die("object %s size inconsistency (%lu vs %lu)",
278                             sha1_to_hex(entry->sha1), size, entry->size);
279                 if (entry->delta) {
280                         buf = delta_against(buf, size, entry);
281                         size = entry->delta_size;
282                         obj_type = OBJ_DELTA;
283                 }
284                 /*
285                  * The object header is a byte of 'type' followed by zero or
286                  * more bytes of length.  For deltas, the 20 bytes of delta
287                  * sha1 follows that.
288                  */
289                 hdrlen = encode_header(obj_type, size, header);
290                 sha1write(f, header, hdrlen);
291
292                 if (entry->delta) {
293                         sha1write(f, entry->delta, 20);
294                         hdrlen += 20;
295                 }
296                 datalen = sha1write_compressed(f, buf, size);
297                 free(buf);
298         }
299         else {
300                 struct packed_git *p = entry->in_pack;
301                 use_packed_git(p);
302
303                 datalen = find_packed_object_size(p, entry->in_pack_offset);
304                 buf = p->pack_base + entry->in_pack_offset;
305                 sha1write(f, buf, datalen);
306                 unuse_packed_git(p);
307                 hdrlen = 0; /* not really */
308                 if (obj_type == OBJ_DELTA)
309                         reused_delta++;
310                 reused++;
311         }
312         if (obj_type == OBJ_DELTA)
313                 written_delta++;
314         written++;
315         return hdrlen + datalen;
316 }
317
318 static unsigned long write_one(struct sha1file *f,
319                                struct object_entry *e,
320                                unsigned long offset)
321 {
322         if (e->offset)
323                 /* offset starts from header size and cannot be zero
324                  * if it is written already.
325                  */
326                 return offset;
327         e->offset = offset;
328         offset += write_object(f, e);
329         /* if we are deltified, write out its base object. */
330         if (e->delta)
331                 offset = write_one(f, e->delta, offset);
332         return offset;
333 }
334
335 static void write_pack_file(void)
336 {
337         int i;
338         struct sha1file *f;
339         unsigned long offset;
340         struct pack_header hdr;
341         unsigned last_percent = 999;
342         int do_progress = 0;
343
344         if (!base_name)
345                 f = sha1fd(1, "<stdout>");
346         else {
347                 f = sha1create("%s-%s.%s", base_name,
348                                sha1_to_hex(object_list_sha1), "pack");
349                 do_progress = progress;
350         }
351         if (do_progress)
352                 fprintf(stderr, "Writing %d objects.\n", nr_result);
353
354         hdr.hdr_signature = htonl(PACK_SIGNATURE);
355         hdr.hdr_version = htonl(PACK_VERSION);
356         hdr.hdr_entries = htonl(nr_result);
357         sha1write(f, &hdr, sizeof(hdr));
358         offset = sizeof(hdr);
359         if (!nr_result)
360                 goto done;
361         for (i = 0; i < nr_objects; i++) {
362                 offset = write_one(f, objects + i, offset);
363                 if (do_progress) {
364                         unsigned percent = written * 100 / nr_result;
365                         if (progress_update || percent != last_percent) {
366                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
367                                         percent, written, nr_result);
368                                 progress_update = 0;
369                                 last_percent = percent;
370                         }
371                 }
372         }
373         if (do_progress)
374                 fputc('\n', stderr);
375  done:
376         sha1close(f, pack_file_sha1, 1);
377 }
378
379 static void write_index_file(void)
380 {
381         int i;
382         struct sha1file *f = sha1create("%s-%s.%s", base_name,
383                                         sha1_to_hex(object_list_sha1), "idx");
384         struct object_entry **list = sorted_by_sha;
385         struct object_entry **last = list + nr_result;
386         unsigned int array[256];
387
388         /*
389          * Write the first-level table (the list is sorted,
390          * but we use a 256-entry lookup to be able to avoid
391          * having to do eight extra binary search iterations).
392          */
393         for (i = 0; i < 256; i++) {
394                 struct object_entry **next = list;
395                 while (next < last) {
396                         struct object_entry *entry = *next;
397                         if (entry->sha1[0] != i)
398                                 break;
399                         next++;
400                 }
401                 array[i] = htonl(next - sorted_by_sha);
402                 list = next;
403         }
404         sha1write(f, array, 256 * sizeof(int));
405
406         /*
407          * Write the actual SHA1 entries..
408          */
409         list = sorted_by_sha;
410         for (i = 0; i < nr_result; i++) {
411                 struct object_entry *entry = *list++;
412                 unsigned int offset = htonl(entry->offset);
413                 sha1write(f, &offset, 4);
414                 sha1write(f, entry->sha1, 20);
415         }
416         sha1write(f, pack_file_sha1, 20);
417         sha1close(f, NULL, 1);
418 }
419
420 static int locate_object_entry_hash(const unsigned char *sha1)
421 {
422         int i;
423         unsigned int ui;
424         memcpy(&ui, sha1, sizeof(unsigned int));
425         i = ui % object_ix_hashsz;
426         while (0 < object_ix[i]) {
427                 if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
428                         return i;
429                 if (++i == object_ix_hashsz)
430                         i = 0;
431         }
432         return -1 - i;
433 }
434
435 static struct object_entry *locate_object_entry(const unsigned char *sha1)
436 {
437         int i;
438
439         if (!object_ix_hashsz)
440                 return NULL;
441
442         i = locate_object_entry_hash(sha1);
443         if (0 <= i)
444                 return &objects[object_ix[i]-1];
445         return NULL;
446 }
447
448 static void rehash_objects(void)
449 {
450         int i;
451         struct object_entry *oe;
452
453         object_ix_hashsz = nr_objects * 3;
454         if (object_ix_hashsz < 1024)
455                 object_ix_hashsz = 1024;
456         object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
457         memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
458         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
459                 int ix = locate_object_entry_hash(oe->sha1);
460                 if (0 <= ix)
461                         continue;
462                 ix = -1 - ix;
463                 object_ix[ix] = i + 1;
464         }
465 }
466
467 struct name_path {
468         struct name_path *up;
469         const char *elem;
470         int len;
471 };
472
473 #define DIRBITS 12
474
475 static unsigned name_hash(struct name_path *path, const char *name)
476 {
477         struct name_path *p = path;
478         const char *n = name + strlen(name);
479         unsigned hash = 0, name_hash = 0, name_done = 0;
480
481         if (n != name && n[-1] == '\n')
482                 n--;
483         while (name <= --n) {
484                 unsigned char c = *n;
485                 if (c == '/' && !name_done) {
486                         name_hash = hash;
487                         name_done = 1;
488                         hash = 0;
489                 }
490                 hash = hash * 11 + c;
491         }
492         if (!name_done) {
493                 name_hash = hash;
494                 hash = 0;
495         }
496         for (p = path; p; p = p->up) {
497                 hash = hash * 11 + '/';
498                 n = p->elem + p->len;
499                 while (p->elem <= --n) {
500                         unsigned char c = *n;
501                         hash = hash * 11 + c;
502                 }
503         }
504         /*
505          * Make sure "Makefile" and "t/Makefile" are hashed separately
506          * but close enough.
507          */
508         hash = (name_hash<<DIRBITS) | (hash & ((1U<<DIRBITS )-1));
509         return hash;
510 }
511
512 static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
513 {
514         unsigned int idx = nr_objects;
515         struct object_entry *entry;
516         struct packed_git *p;
517         unsigned int found_offset = 0;
518         struct packed_git *found_pack = NULL;
519         int ix, status = 0;
520
521         if (!exclude) {
522                 for (p = packed_git; p; p = p->next) {
523                         struct pack_entry e;
524                         if (find_pack_entry_one(sha1, &e, p)) {
525                                 if (incremental)
526                                         return 0;
527                                 if (local && !p->pack_local)
528                                         return 0;
529                                 if (!found_pack) {
530                                         found_offset = e.offset;
531                                         found_pack = e.p;
532                                 }
533                         }
534                 }
535         }
536         if ((entry = locate_object_entry(sha1)) != NULL)
537                 goto already_added;
538
539         if (idx >= nr_alloc) {
540                 unsigned int needed = (idx + 1024) * 3 / 2;
541                 objects = xrealloc(objects, needed * sizeof(*entry));
542                 nr_alloc = needed;
543         }
544         entry = objects + idx;
545         nr_objects = idx + 1;
546         memset(entry, 0, sizeof(*entry));
547         memcpy(entry->sha1, sha1, 20);
548         entry->hash = hash;
549
550         if (object_ix_hashsz * 3 <= nr_objects * 4)
551                 rehash_objects();
552         else {
553                 ix = locate_object_entry_hash(entry->sha1);
554                 if (0 <= ix)
555                         die("internal error in object hashing.");
556                 object_ix[-1 - ix] = idx + 1;
557         }
558         status = 1;
559
560  already_added:
561         if (progress_update) {
562                 fprintf(stderr, "Counting objects...%d\r", nr_objects);
563                 progress_update = 0;
564         }
565         if (exclude)
566                 entry->preferred_base = 1;
567         else {
568                 if (found_pack) {
569                         entry->in_pack = found_pack;
570                         entry->in_pack_offset = found_offset;
571                 }
572         }
573         return status;
574 }
575
576 struct pbase_tree_cache {
577         unsigned char sha1[20];
578         int ref;
579         int temporary;
580         void *tree_data;
581         unsigned long tree_size;
582 };
583
584 static struct pbase_tree_cache *(pbase_tree_cache[256]);
585 static int pbase_tree_cache_ix(const unsigned char *sha1)
586 {
587         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
588 }
589 static int pbase_tree_cache_ix_incr(int ix)
590 {
591         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
592 }
593
594 static struct pbase_tree {
595         struct pbase_tree *next;
596         /* This is a phony "cache" entry; we are not
597          * going to evict it nor find it through _get()
598          * mechanism -- this is for the toplevel node that
599          * would almost always change with any commit.
600          */
601         struct pbase_tree_cache pcache;
602 } *pbase_tree;
603
604 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
605 {
606         struct pbase_tree_cache *ent, *nent;
607         void *data;
608         unsigned long size;
609         char type[20];
610         int neigh;
611         int my_ix = pbase_tree_cache_ix(sha1);
612         int available_ix = -1;
613
614         /* pbase-tree-cache acts as a limited hashtable.
615          * your object will be found at your index or within a few
616          * slots after that slot if it is cached.
617          */
618         for (neigh = 0; neigh < 8; neigh++) {
619                 ent = pbase_tree_cache[my_ix];
620                 if (ent && !memcmp(ent->sha1, sha1, 20)) {
621                         ent->ref++;
622                         return ent;
623                 }
624                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
625                          ((0 <= available_ix) &&
626                           (!ent && pbase_tree_cache[available_ix])))
627                         available_ix = my_ix;
628                 if (!ent)
629                         break;
630                 my_ix = pbase_tree_cache_ix_incr(my_ix);
631         }
632
633         /* Did not find one.  Either we got a bogus request or
634          * we need to read and perhaps cache.
635          */
636         data = read_sha1_file(sha1, type, &size);
637         if (!data)
638                 return NULL;
639         if (strcmp(type, tree_type)) {
640                 free(data);
641                 return NULL;
642         }
643
644         /* We need to either cache or return a throwaway copy */
645
646         if (available_ix < 0)
647                 ent = NULL;
648         else {
649                 ent = pbase_tree_cache[available_ix];
650                 my_ix = available_ix;
651         }
652
653         if (!ent) {
654                 nent = xmalloc(sizeof(*nent));
655                 nent->temporary = (available_ix < 0);
656         }
657         else {
658                 /* evict and reuse */
659                 free(ent->tree_data);
660                 nent = ent;
661         }
662         memcpy(nent->sha1, sha1, 20);
663         nent->tree_data = data;
664         nent->tree_size = size;
665         nent->ref = 1;
666         if (!nent->temporary)
667                 pbase_tree_cache[my_ix] = nent;
668         return nent;
669 }
670
671 static void pbase_tree_put(struct pbase_tree_cache *cache)
672 {
673         if (!cache->temporary) {
674                 cache->ref--;
675                 return;
676         }
677         free(cache->tree_data);
678         free(cache);
679 }
680
681 static int name_cmp_len(const char *name)
682 {
683         int i;
684         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
685                 ;
686         return i;
687 }
688
689 static void add_pbase_object(struct tree_desc *tree,
690                              struct name_path *up,
691                              const char *name,
692                              int cmplen)
693 {
694         while (tree->size) {
695                 const unsigned char *sha1;
696                 const char *entry_name;
697                 int entry_len;
698                 unsigned mode;
699                 unsigned long size;
700                 char type[20];
701
702                 sha1 = tree_entry_extract(tree, &entry_name, &mode);
703                 update_tree_entry(tree);
704                 entry_len = strlen(entry_name);
705                 if (entry_len != cmplen ||
706                     memcmp(entry_name, name, cmplen) ||
707                     !has_sha1_file(sha1) ||
708                     sha1_object_info(sha1, type, &size))
709                         continue;
710                 if (name[cmplen] != '/') {
711                         unsigned hash = name_hash(up, name);
712                         add_object_entry(sha1, hash, 1);
713                         return;
714                 }
715                 if (!strcmp(type, tree_type)) {
716                         struct tree_desc sub;
717                         struct name_path me;
718                         struct pbase_tree_cache *tree;
719                         const char *down = name+cmplen+1;
720                         int downlen = name_cmp_len(down);
721
722                         tree = pbase_tree_get(sha1);
723                         if (!tree)
724                                 return;
725                         sub.buf = tree->tree_data;
726                         sub.size = tree->tree_size;
727
728                         me.up = up;
729                         me.elem = entry_name;
730                         me.len = entry_len;
731                         add_pbase_object(&sub, &me, down, downlen);
732                         pbase_tree_put(tree);
733                 }
734         }
735 }
736
737 static unsigned *done_pbase_paths;
738 static int done_pbase_paths_num;
739 static int done_pbase_paths_alloc;
740 static int done_pbase_path_pos(unsigned hash)
741 {
742         int lo = 0;
743         int hi = done_pbase_paths_num;
744         while (lo < hi) {
745                 int mi = (hi + lo) / 2;
746                 if (done_pbase_paths[mi] == hash)
747                         return mi;
748                 if (done_pbase_paths[mi] < hash)
749                         hi = mi;
750                 else
751                         lo = mi + 1;
752         }
753         return -lo-1;
754 }
755
756 static int check_pbase_path(unsigned hash)
757 {
758         int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
759         if (0 <= pos)
760                 return 1;
761         pos = -pos - 1;
762         if (done_pbase_paths_alloc <= done_pbase_paths_num) {
763                 done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
764                 done_pbase_paths = xrealloc(done_pbase_paths,
765                                             done_pbase_paths_alloc *
766                                             sizeof(unsigned));
767         }
768         done_pbase_paths_num++;
769         if (pos < done_pbase_paths_num)
770                 memmove(done_pbase_paths + pos + 1,
771                         done_pbase_paths + pos,
772                         (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
773         done_pbase_paths[pos] = hash;
774         return 0;
775 }
776
777 static void add_preferred_base_object(char *name, unsigned hash)
778 {
779         struct pbase_tree *it;
780         int cmplen = name_cmp_len(name);
781
782         if (check_pbase_path(hash))
783                 return;
784
785         for (it = pbase_tree; it; it = it->next) {
786                 if (cmplen == 0) {
787                         hash = name_hash(NULL, "");
788                         add_object_entry(it->pcache.sha1, hash, 1);
789                 }
790                 else {
791                         struct tree_desc tree;
792                         tree.buf = it->pcache.tree_data;
793                         tree.size = it->pcache.tree_size;
794                         add_pbase_object(&tree, NULL, name, cmplen);
795                 }
796         }
797 }
798
799 static void add_preferred_base(unsigned char *sha1)
800 {
801         struct pbase_tree *it;
802         void *data;
803         unsigned long size;
804         unsigned char tree_sha1[20];
805
806         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
807         if (!data)
808                 return;
809
810         for (it = pbase_tree; it; it = it->next) {
811                 if (!memcmp(it->pcache.sha1, tree_sha1, 20)) {
812                         free(data);
813                         return;
814                 }
815         }
816
817         it = xcalloc(1, sizeof(*it));
818         it->next = pbase_tree;
819         pbase_tree = it;
820
821         memcpy(it->pcache.sha1, tree_sha1, 20);
822         it->pcache.tree_data = data;
823         it->pcache.tree_size = size;
824 }
825
826 static void check_object(struct object_entry *entry)
827 {
828         char type[20];
829
830         if (entry->in_pack && !entry->preferred_base) {
831                 unsigned char base[20];
832                 unsigned long size;
833                 struct object_entry *base_entry;
834
835                 /* We want in_pack_type even if we do not reuse delta.
836                  * There is no point not reusing non-delta representations.
837                  */
838                 check_reuse_pack_delta(entry->in_pack,
839                                        entry->in_pack_offset,
840                                        base, &size,
841                                        &entry->in_pack_type);
842
843                 /* Check if it is delta, and the base is also an object
844                  * we are going to pack.  If so we will reuse the existing
845                  * delta.
846                  */
847                 if (!no_reuse_delta &&
848                     entry->in_pack_type == OBJ_DELTA &&
849                     (base_entry = locate_object_entry(base)) &&
850                     (!base_entry->preferred_base)) {
851
852                         /* Depth value does not matter - find_deltas()
853                          * will never consider reused delta as the
854                          * base object to deltify other objects
855                          * against, in order to avoid circular deltas.
856                          */
857
858                         /* uncompressed size of the delta data */
859                         entry->size = entry->delta_size = size;
860                         entry->delta = base_entry;
861                         entry->type = OBJ_DELTA;
862
863                         entry->delta_sibling = base_entry->delta_child;
864                         base_entry->delta_child = entry;
865
866                         return;
867                 }
868                 /* Otherwise we would do the usual */
869         }
870
871         if (sha1_object_info(entry->sha1, type, &entry->size))
872                 die("unable to get type of object %s",
873                     sha1_to_hex(entry->sha1));
874
875         if (!strcmp(type, commit_type)) {
876                 entry->type = OBJ_COMMIT;
877         } else if (!strcmp(type, tree_type)) {
878                 entry->type = OBJ_TREE;
879         } else if (!strcmp(type, blob_type)) {
880                 entry->type = OBJ_BLOB;
881         } else if (!strcmp(type, tag_type)) {
882                 entry->type = OBJ_TAG;
883         } else
884                 die("unable to pack object %s of type %s",
885                     sha1_to_hex(entry->sha1), type);
886 }
887
888 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
889 {
890         struct object_entry *child = me->delta_child;
891         unsigned int m = n;
892         while (child) {
893                 unsigned int c = check_delta_limit(child, n + 1);
894                 if (m < c)
895                         m = c;
896                 child = child->delta_sibling;
897         }
898         return m;
899 }
900
901 static void get_object_details(void)
902 {
903         int i;
904         struct object_entry *entry;
905
906         prepare_pack_ix();
907         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
908                 check_object(entry);
909
910         if (nr_objects == nr_result) {
911                 /*
912                  * Depth of objects that depend on the entry -- this
913                  * is subtracted from depth-max to break too deep
914                  * delta chain because of delta data reusing.
915                  * However, we loosen this restriction when we know we
916                  * are creating a thin pack -- it will have to be
917                  * expanded on the other end anyway, so do not
918                  * artificially cut the delta chain and let it go as
919                  * deep as it wants.
920                  */
921                 for (i = 0, entry = objects; i < nr_objects; i++, entry++)
922                         if (!entry->delta && entry->delta_child)
923                                 entry->delta_limit =
924                                         check_delta_limit(entry, 1);
925         }
926 }
927
928 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
929
930 static entry_sort_t current_sort;
931
932 static int sort_comparator(const void *_a, const void *_b)
933 {
934         struct object_entry *a = *(struct object_entry **)_a;
935         struct object_entry *b = *(struct object_entry **)_b;
936         return current_sort(a,b);
937 }
938
939 static struct object_entry **create_sorted_list(entry_sort_t sort)
940 {
941         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
942         int i;
943
944         for (i = 0; i < nr_objects; i++)
945                 list[i] = objects + i;
946         current_sort = sort;
947         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
948         return list;
949 }
950
951 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
952 {
953         return memcmp(a->sha1, b->sha1, 20);
954 }
955
956 static struct object_entry **create_final_object_list(void)
957 {
958         struct object_entry **list;
959         int i, j;
960
961         for (i = nr_result = 0; i < nr_objects; i++)
962                 if (!objects[i].preferred_base)
963                         nr_result++;
964         list = xmalloc(nr_result * sizeof(struct object_entry *));
965         for (i = j = 0; i < nr_objects; i++) {
966                 if (!objects[i].preferred_base)
967                         list[j++] = objects + i;
968         }
969         current_sort = sha1_sort;
970         qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
971         return list;
972 }
973
974 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
975 {
976         if (a->type < b->type)
977                 return -1;
978         if (a->type > b->type)
979                 return 1;
980         if (a->hash < b->hash)
981                 return -1;
982         if (a->hash > b->hash)
983                 return 1;
984         if (a->preferred_base < b->preferred_base)
985                 return -1;
986         if (a->preferred_base > b->preferred_base)
987                 return 1;
988         if (a->size < b->size)
989                 return -1;
990         if (a->size > b->size)
991                 return 1;
992         return a < b ? -1 : (a > b);
993 }
994
995 struct unpacked {
996         struct object_entry *entry;
997         void *data;
998         struct delta_index *index;
999 };
1000
1001 /*
1002  * We search for deltas _backwards_ in a list sorted by type and
1003  * by size, so that we see progressively smaller and smaller files.
1004  * That's because we prefer deltas to be from the bigger file
1005  * to the smaller - deletes are potentially cheaper, but perhaps
1006  * more importantly, the bigger file is likely the more recent
1007  * one.
1008  */
1009 static int try_delta(struct unpacked *trg, struct unpacked *src,
1010                      struct delta_index *src_index, unsigned max_depth)
1011 {
1012         struct object_entry *trg_entry = trg->entry;
1013         struct object_entry *src_entry = src->entry;
1014         unsigned long size, src_size, delta_size, sizediff, max_size;
1015         void *delta_buf;
1016
1017         /* Don't bother doing diffs between different types */
1018         if (trg_entry->type != src_entry->type)
1019                 return -1;
1020
1021         /* We do not compute delta to *create* objects we are not
1022          * going to pack.
1023          */
1024         if (trg_entry->preferred_base)
1025                 return -1;
1026
1027         /*
1028          * If the current object is at pack edge, take the depth the
1029          * objects that depend on the current object into account --
1030          * otherwise they would become too deep.
1031          */
1032         if (trg_entry->delta_child) {
1033                 if (max_depth <= trg_entry->delta_limit)
1034                         return 0;
1035                 max_depth -= trg_entry->delta_limit;
1036         }
1037         if (src_entry->depth >= max_depth)
1038                 return 0;
1039
1040         /* Now some size filtering euristics. */
1041         size = trg_entry->size;
1042         max_size = size / 2 - 20;
1043         if (trg_entry->delta)
1044                 max_size = trg_entry->delta_size-1;
1045         src_size = src_entry->size;
1046         sizediff = src_size < size ? size - src_size : 0;
1047         if (sizediff >= max_size)
1048                 return 0;
1049
1050         delta_buf = create_delta(src_index, trg->data, size, &delta_size, max_size);
1051         if (!delta_buf)
1052                 return 0;
1053
1054         trg_entry->delta = src_entry;
1055         trg_entry->delta_size = delta_size;
1056         trg_entry->depth = src_entry->depth + 1;
1057         free(delta_buf);
1058         return 1;
1059 }
1060
1061 static void progress_interval(int signum)
1062 {
1063         progress_update = 1;
1064 }
1065
1066 static void find_deltas(struct object_entry **list, int window, int depth)
1067 {
1068         int i, idx;
1069         unsigned int array_size = window * sizeof(struct unpacked);
1070         struct unpacked *array = xmalloc(array_size);
1071         unsigned processed = 0;
1072         unsigned last_percent = 999;
1073
1074         memset(array, 0, array_size);
1075         i = nr_objects;
1076         idx = 0;
1077         if (progress)
1078                 fprintf(stderr, "Deltifying %d objects.\n", nr_result);
1079
1080         while (--i >= 0) {
1081                 struct object_entry *entry = list[i];
1082                 struct unpacked *n = array + idx;
1083                 unsigned long size;
1084                 char type[10];
1085                 int j;
1086
1087                 if (!entry->preferred_base)
1088                         processed++;
1089
1090                 if (progress) {
1091                         unsigned percent = processed * 100 / nr_result;
1092                         if (percent != last_percent || progress_update) {
1093                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
1094                                         percent, processed, nr_result);
1095                                 progress_update = 0;
1096                                 last_percent = percent;
1097                         }
1098                 }
1099
1100                 if (entry->delta)
1101                         /* This happens if we decided to reuse existing
1102                          * delta from a pack.  "!no_reuse_delta &&" is implied.
1103                          */
1104                         continue;
1105
1106                 if (entry->size < 50)
1107                         continue;
1108                 if (n->index)
1109                         free_delta_index(n->index);
1110                 free(n->data);
1111                 n->entry = entry;
1112                 n->data = read_sha1_file(entry->sha1, type, &size);
1113                 if (size != entry->size)
1114                         die("object %s inconsistent object length (%lu vs %lu)",
1115                             sha1_to_hex(entry->sha1), size, entry->size);
1116                 n->index = create_delta_index(n->data, size);
1117                 if (!n->index)
1118                         die("out of memory");
1119
1120                 j = window;
1121                 while (--j > 0) {
1122                         unsigned int other_idx = idx + j;
1123                         struct unpacked *m;
1124                         if (other_idx >= window)
1125                                 other_idx -= window;
1126                         m = array + other_idx;
1127                         if (!m->entry)
1128                                 break;
1129                         if (try_delta(n, m, m->index, depth) < 0)
1130                                 break;
1131                 }
1132 #if 0
1133                 /* if we made n a delta, and if n is already at max
1134                  * depth, leaving it in the window is pointless.  we
1135                  * should evict it first.
1136                  * ... in theory only; somehow this makes things worse.
1137                  */
1138                 if (entry->delta && depth <= entry->depth)
1139                         continue;
1140 #endif
1141                 idx++;
1142                 if (idx >= window)
1143                         idx = 0;
1144         }
1145
1146         if (progress)
1147                 fputc('\n', stderr);
1148
1149         for (i = 0; i < window; ++i) {
1150                 if (array[i].index)
1151                         free_delta_index(array[i].index);
1152                 free(array[i].data);
1153         }
1154         free(array);
1155 }
1156
1157 static void prepare_pack(int window, int depth)
1158 {
1159         get_object_details();
1160         sorted_by_type = create_sorted_list(type_size_sort);
1161         if (window && depth)
1162                 find_deltas(sorted_by_type, window+1, depth);
1163 }
1164
1165 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
1166 {
1167         static const char cache[] = "pack-cache/pack-%s.%s";
1168         char *cached_pack, *cached_idx;
1169         int ifd, ofd, ifd_ix = -1;
1170
1171         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
1172         ifd = open(cached_pack, O_RDONLY);
1173         if (ifd < 0)
1174                 return 0;
1175
1176         if (!pack_to_stdout) {
1177                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1178                 ifd_ix = open(cached_idx, O_RDONLY);
1179                 if (ifd_ix < 0) {
1180                         close(ifd);
1181                         return 0;
1182                 }
1183         }
1184
1185         if (progress)
1186                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
1187                         sha1_to_hex(sha1));
1188
1189         if (pack_to_stdout) {
1190                 if (copy_fd(ifd, 1))
1191                         exit(1);
1192                 close(ifd);
1193         }
1194         else {
1195                 char name[PATH_MAX];
1196                 snprintf(name, sizeof(name),
1197                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1198                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1199                 if (ofd < 0)
1200                         die("unable to open %s (%s)", name, strerror(errno));
1201                 if (copy_fd(ifd, ofd))
1202                         exit(1);
1203                 close(ifd);
1204
1205                 snprintf(name, sizeof(name),
1206                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1207                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1208                 if (ofd < 0)
1209                         die("unable to open %s (%s)", name, strerror(errno));
1210                 if (copy_fd(ifd_ix, ofd))
1211                         exit(1);
1212                 close(ifd_ix);
1213                 puts(sha1_to_hex(sha1));
1214         }
1215
1216         return 1;
1217 }
1218
1219 static void setup_progress_signal(void)
1220 {
1221         struct sigaction sa;
1222         struct itimerval v;
1223
1224         memset(&sa, 0, sizeof(sa));
1225         sa.sa_handler = progress_interval;
1226         sigemptyset(&sa.sa_mask);
1227         sa.sa_flags = SA_RESTART;
1228         sigaction(SIGALRM, &sa, NULL);
1229
1230         v.it_interval.tv_sec = 1;
1231         v.it_interval.tv_usec = 0;
1232         v.it_value = v.it_interval;
1233         setitimer(ITIMER_REAL, &v, NULL);
1234 }
1235
1236 int main(int argc, char **argv)
1237 {
1238         SHA_CTX ctx;
1239         char line[40 + 1 + PATH_MAX + 2];
1240         int window = 10, depth = 10, pack_to_stdout = 0;
1241         struct object_entry **list;
1242         int num_preferred_base = 0;
1243         int i;
1244
1245         setup_git_directory();
1246
1247         progress = isatty(2);
1248         for (i = 1; i < argc; i++) {
1249                 const char *arg = argv[i];
1250
1251                 if (*arg == '-') {
1252                         if (!strcmp("--non-empty", arg)) {
1253                                 non_empty = 1;
1254                                 continue;
1255                         }
1256                         if (!strcmp("--local", arg)) {
1257                                 local = 1;
1258                                 continue;
1259                         }
1260                         if (!strcmp("--incremental", arg)) {
1261                                 incremental = 1;
1262                                 continue;
1263                         }
1264                         if (!strncmp("--window=", arg, 9)) {
1265                                 char *end;
1266                                 window = strtoul(arg+9, &end, 0);
1267                                 if (!arg[9] || *end)
1268                                         usage(pack_usage);
1269                                 continue;
1270                         }
1271                         if (!strncmp("--depth=", arg, 8)) {
1272                                 char *end;
1273                                 depth = strtoul(arg+8, &end, 0);
1274                                 if (!arg[8] || *end)
1275                                         usage(pack_usage);
1276                                 continue;
1277                         }
1278                         if (!strcmp("--progress", arg)) {
1279                                 progress = 1;
1280                                 continue;
1281                         }
1282                         if (!strcmp("-q", arg)) {
1283                                 progress = 0;
1284                                 continue;
1285                         }
1286                         if (!strcmp("--no-reuse-delta", arg)) {
1287                                 no_reuse_delta = 1;
1288                                 continue;
1289                         }
1290                         if (!strcmp("--stdout", arg)) {
1291                                 pack_to_stdout = 1;
1292                                 continue;
1293                         }
1294                         usage(pack_usage);
1295                 }
1296                 if (base_name)
1297                         usage(pack_usage);
1298                 base_name = arg;
1299         }
1300
1301         if (pack_to_stdout != !base_name)
1302                 usage(pack_usage);
1303
1304         prepare_packed_git();
1305
1306         if (progress) {
1307                 fprintf(stderr, "Generating pack...\n");
1308                 setup_progress_signal();
1309         }
1310
1311         for (;;) {
1312                 unsigned char sha1[20];
1313                 unsigned hash;
1314
1315                 if (!fgets(line, sizeof(line), stdin)) {
1316                         if (feof(stdin))
1317                                 break;
1318                         if (!ferror(stdin))
1319                                 die("fgets returned NULL, not EOF, not error!");
1320                         if (errno != EINTR)
1321                                 die("fgets: %s", strerror(errno));
1322                         clearerr(stdin);
1323                         continue;
1324                 }
1325
1326                 if (line[0] == '-') {
1327                         if (get_sha1_hex(line+1, sha1))
1328                                 die("expected edge sha1, got garbage:\n %s",
1329                                     line+1);
1330                         if (num_preferred_base++ < window)
1331                                 add_preferred_base(sha1);
1332                         continue;
1333                 }
1334                 if (get_sha1_hex(line, sha1))
1335                         die("expected sha1, got garbage:\n %s", line);
1336                 hash = name_hash(NULL, line+41);
1337                 add_preferred_base_object(line+41, hash);
1338                 add_object_entry(sha1, hash, 0);
1339         }
1340         if (progress)
1341                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
1342         sorted_by_sha = create_final_object_list();
1343         if (non_empty && !nr_result)
1344                 return 0;
1345
1346         SHA1_Init(&ctx);
1347         list = sorted_by_sha;
1348         for (i = 0; i < nr_result; i++) {
1349                 struct object_entry *entry = *list++;
1350                 SHA1_Update(&ctx, entry->sha1, 20);
1351         }
1352         SHA1_Final(object_list_sha1, &ctx);
1353         if (progress && (nr_objects != nr_result))
1354                 fprintf(stderr, "Result has %d objects.\n", nr_result);
1355
1356         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
1357                 ;
1358         else {
1359                 if (nr_result)
1360                         prepare_pack(window, depth);
1361                 if (progress && pack_to_stdout) {
1362                         /* the other end usually displays progress itself */
1363                         struct itimerval v = {{0,},};
1364                         setitimer(ITIMER_REAL, &v, NULL);
1365                         signal(SIGALRM, SIG_IGN );
1366                         progress_update = 0;
1367                 }
1368                 write_pack_file();
1369                 if (!pack_to_stdout) {
1370                         write_index_file();
1371                         puts(sha1_to_hex(object_list_sha1));
1372                 }
1373         }
1374         if (progress)
1375                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
1376                         nr_result, written, written_delta, reused, reused_delta);
1377         return 0;
1378 }