unpack-trees: add a note about path invalidation
[git] / cache-tree.c
1 #include "cache.h"
2 #include "lockfile.h"
3 #include "tree.h"
4 #include "tree-walk.h"
5 #include "cache-tree.h"
6 #include "object-store.h"
7
8 #ifndef DEBUG
9 #define DEBUG 0
10 #endif
11
12 struct cache_tree *cache_tree(void)
13 {
14         struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));
15         it->entry_count = -1;
16         return it;
17 }
18
19 void cache_tree_free(struct cache_tree **it_p)
20 {
21         int i;
22         struct cache_tree *it = *it_p;
23
24         if (!it)
25                 return;
26         for (i = 0; i < it->subtree_nr; i++)
27                 if (it->down[i]) {
28                         cache_tree_free(&it->down[i]->cache_tree);
29                         free(it->down[i]);
30                 }
31         free(it->down);
32         free(it);
33         *it_p = NULL;
34 }
35
36 static int subtree_name_cmp(const char *one, int onelen,
37                             const char *two, int twolen)
38 {
39         if (onelen < twolen)
40                 return -1;
41         if (twolen < onelen)
42                 return 1;
43         return memcmp(one, two, onelen);
44 }
45
46 static int subtree_pos(struct cache_tree *it, const char *path, int pathlen)
47 {
48         struct cache_tree_sub **down = it->down;
49         int lo, hi;
50         lo = 0;
51         hi = it->subtree_nr;
52         while (lo < hi) {
53                 int mi = lo + (hi - lo) / 2;
54                 struct cache_tree_sub *mdl = down[mi];
55                 int cmp = subtree_name_cmp(path, pathlen,
56                                            mdl->name, mdl->namelen);
57                 if (!cmp)
58                         return mi;
59                 if (cmp < 0)
60                         hi = mi;
61                 else
62                         lo = mi + 1;
63         }
64         return -lo-1;
65 }
66
67 static struct cache_tree_sub *find_subtree(struct cache_tree *it,
68                                            const char *path,
69                                            int pathlen,
70                                            int create)
71 {
72         struct cache_tree_sub *down;
73         int pos = subtree_pos(it, path, pathlen);
74         if (0 <= pos)
75                 return it->down[pos];
76         if (!create)
77                 return NULL;
78
79         pos = -pos-1;
80         ALLOC_GROW(it->down, it->subtree_nr + 1, it->subtree_alloc);
81         it->subtree_nr++;
82
83         FLEX_ALLOC_MEM(down, name, path, pathlen);
84         down->cache_tree = NULL;
85         down->namelen = pathlen;
86
87         if (pos < it->subtree_nr)
88                 MOVE_ARRAY(it->down + pos + 1, it->down + pos,
89                            it->subtree_nr - pos - 1);
90         it->down[pos] = down;
91         return down;
92 }
93
94 struct cache_tree_sub *cache_tree_sub(struct cache_tree *it, const char *path)
95 {
96         int pathlen = strlen(path);
97         return find_subtree(it, path, pathlen, 1);
98 }
99
100 static int do_invalidate_path(struct cache_tree *it, const char *path)
101 {
102         /* a/b/c
103          * ==> invalidate self
104          * ==> find "a", have it invalidate "b/c"
105          * a
106          * ==> invalidate self
107          * ==> if "a" exists as a subtree, remove it.
108          */
109         const char *slash;
110         int namelen;
111         struct cache_tree_sub *down;
112
113 #if DEBUG
114         fprintf(stderr, "cache-tree invalidate <%s>\n", path);
115 #endif
116
117         if (!it)
118                 return 0;
119         slash = strchrnul(path, '/');
120         namelen = slash - path;
121         it->entry_count = -1;
122         if (!*slash) {
123                 int pos;
124                 pos = subtree_pos(it, path, namelen);
125                 if (0 <= pos) {
126                         cache_tree_free(&it->down[pos]->cache_tree);
127                         free(it->down[pos]);
128                         /* 0 1 2 3 4 5
129                          *       ^     ^subtree_nr = 6
130                          *       pos
131                          * move 4 and 5 up one place (2 entries)
132                          * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
133                          */
134                         MOVE_ARRAY(it->down + pos, it->down + pos + 1,
135                                    it->subtree_nr - pos - 1);
136                         it->subtree_nr--;
137                 }
138                 return 1;
139         }
140         down = find_subtree(it, path, namelen, 0);
141         if (down)
142                 do_invalidate_path(down->cache_tree, slash + 1);
143         return 1;
144 }
145
146 void cache_tree_invalidate_path(struct index_state *istate, const char *path)
147 {
148         if (do_invalidate_path(istate->cache_tree, path))
149                 istate->cache_changed |= CACHE_TREE_CHANGED;
150 }
151
152 static int verify_cache(struct cache_entry **cache,
153                         int entries, int flags)
154 {
155         int i, funny;
156         int silent = flags & WRITE_TREE_SILENT;
157
158         /* Verify that the tree is merged */
159         funny = 0;
160         for (i = 0; i < entries; i++) {
161                 const struct cache_entry *ce = cache[i];
162                 if (ce_stage(ce)) {
163                         if (silent)
164                                 return -1;
165                         if (10 < ++funny) {
166                                 fprintf(stderr, "...\n");
167                                 break;
168                         }
169                         fprintf(stderr, "%s: unmerged (%s)\n",
170                                 ce->name, oid_to_hex(&ce->oid));
171                 }
172         }
173         if (funny)
174                 return -1;
175
176         /* Also verify that the cache does not have path and path/file
177          * at the same time.  At this point we know the cache has only
178          * stage 0 entries.
179          */
180         funny = 0;
181         for (i = 0; i < entries - 1; i++) {
182                 /* path/file always comes after path because of the way
183                  * the cache is sorted.  Also path can appear only once,
184                  * which means conflicting one would immediately follow.
185                  */
186                 const char *this_name = cache[i]->name;
187                 const char *next_name = cache[i+1]->name;
188                 int this_len = strlen(this_name);
189                 if (this_len < strlen(next_name) &&
190                     strncmp(this_name, next_name, this_len) == 0 &&
191                     next_name[this_len] == '/') {
192                         if (10 < ++funny) {
193                                 fprintf(stderr, "...\n");
194                                 break;
195                         }
196                         fprintf(stderr, "You have both %s and %s\n",
197                                 this_name, next_name);
198                 }
199         }
200         if (funny)
201                 return -1;
202         return 0;
203 }
204
205 static void discard_unused_subtrees(struct cache_tree *it)
206 {
207         struct cache_tree_sub **down = it->down;
208         int nr = it->subtree_nr;
209         int dst, src;
210         for (dst = src = 0; src < nr; src++) {
211                 struct cache_tree_sub *s = down[src];
212                 if (s->used)
213                         down[dst++] = s;
214                 else {
215                         cache_tree_free(&s->cache_tree);
216                         free(s);
217                         it->subtree_nr--;
218                 }
219         }
220 }
221
222 int cache_tree_fully_valid(struct cache_tree *it)
223 {
224         int i;
225         if (!it)
226                 return 0;
227         if (it->entry_count < 0 || !has_sha1_file(it->oid.hash))
228                 return 0;
229         for (i = 0; i < it->subtree_nr; i++) {
230                 if (!cache_tree_fully_valid(it->down[i]->cache_tree))
231                         return 0;
232         }
233         return 1;
234 }
235
236 static int update_one(struct cache_tree *it,
237                       struct cache_entry **cache,
238                       int entries,
239                       const char *base,
240                       int baselen,
241                       int *skip_count,
242                       int flags)
243 {
244         struct strbuf buffer;
245         int missing_ok = flags & WRITE_TREE_MISSING_OK;
246         int dryrun = flags & WRITE_TREE_DRY_RUN;
247         int repair = flags & WRITE_TREE_REPAIR;
248         int to_invalidate = 0;
249         int i;
250
251         assert(!(dryrun && repair));
252
253         *skip_count = 0;
254
255         if (0 <= it->entry_count && has_sha1_file(it->oid.hash))
256                 return it->entry_count;
257
258         /*
259          * We first scan for subtrees and update them; we start by
260          * marking existing subtrees -- the ones that are unmarked
261          * should not be in the result.
262          */
263         for (i = 0; i < it->subtree_nr; i++)
264                 it->down[i]->used = 0;
265
266         /*
267          * Find the subtrees and update them.
268          */
269         i = 0;
270         while (i < entries) {
271                 const struct cache_entry *ce = cache[i];
272                 struct cache_tree_sub *sub;
273                 const char *path, *slash;
274                 int pathlen, sublen, subcnt, subskip;
275
276                 path = ce->name;
277                 pathlen = ce_namelen(ce);
278                 if (pathlen <= baselen || memcmp(base, path, baselen))
279                         break; /* at the end of this level */
280
281                 slash = strchr(path + baselen, '/');
282                 if (!slash) {
283                         i++;
284                         continue;
285                 }
286                 /*
287                  * a/bbb/c (base = a/, slash = /c)
288                  * ==>
289                  * path+baselen = bbb/c, sublen = 3
290                  */
291                 sublen = slash - (path + baselen);
292                 sub = find_subtree(it, path + baselen, sublen, 1);
293                 if (!sub->cache_tree)
294                         sub->cache_tree = cache_tree();
295                 subcnt = update_one(sub->cache_tree,
296                                     cache + i, entries - i,
297                                     path,
298                                     baselen + sublen + 1,
299                                     &subskip,
300                                     flags);
301                 if (subcnt < 0)
302                         return subcnt;
303                 if (!subcnt)
304                         die("index cache-tree records empty sub-tree");
305                 i += subcnt;
306                 sub->count = subcnt; /* to be used in the next loop */
307                 *skip_count += subskip;
308                 sub->used = 1;
309         }
310
311         discard_unused_subtrees(it);
312
313         /*
314          * Then write out the tree object for this level.
315          */
316         strbuf_init(&buffer, 8192);
317
318         i = 0;
319         while (i < entries) {
320                 const struct cache_entry *ce = cache[i];
321                 struct cache_tree_sub *sub = NULL;
322                 const char *path, *slash;
323                 int pathlen, entlen;
324                 const struct object_id *oid;
325                 unsigned mode;
326                 int expected_missing = 0;
327                 int contains_ita = 0;
328
329                 path = ce->name;
330                 pathlen = ce_namelen(ce);
331                 if (pathlen <= baselen || memcmp(base, path, baselen))
332                         break; /* at the end of this level */
333
334                 slash = strchr(path + baselen, '/');
335                 if (slash) {
336                         entlen = slash - (path + baselen);
337                         sub = find_subtree(it, path + baselen, entlen, 0);
338                         if (!sub)
339                                 die("cache-tree.c: '%.*s' in '%s' not found",
340                                     entlen, path + baselen, path);
341                         i += sub->count;
342                         oid = &sub->cache_tree->oid;
343                         mode = S_IFDIR;
344                         contains_ita = sub->cache_tree->entry_count < 0;
345                         if (contains_ita) {
346                                 to_invalidate = 1;
347                                 expected_missing = 1;
348                         }
349                 }
350                 else {
351                         oid = &ce->oid;
352                         mode = ce->ce_mode;
353                         entlen = pathlen - baselen;
354                         i++;
355                 }
356
357                 if (is_null_oid(oid) ||
358                     (mode != S_IFGITLINK && !missing_ok && !has_object_file(oid))) {
359                         strbuf_release(&buffer);
360                         if (expected_missing)
361                                 return -1;
362                         return error("invalid object %06o %s for '%.*s'",
363                                 mode, oid_to_hex(oid), entlen+baselen, path);
364                 }
365
366                 /*
367                  * CE_REMOVE entries are removed before the index is
368                  * written to disk. Skip them to remain consistent
369                  * with the future on-disk index.
370                  */
371                 if (ce->ce_flags & CE_REMOVE) {
372                         *skip_count = *skip_count + 1;
373                         continue;
374                 }
375
376                 /*
377                  * CE_INTENT_TO_ADD entries exist on on-disk index but
378                  * they are not part of generated trees. Invalidate up
379                  * to root to force cache-tree users to read elsewhere.
380                  */
381                 if (!sub && ce_intent_to_add(ce)) {
382                         to_invalidate = 1;
383                         continue;
384                 }
385
386                 /*
387                  * "sub" can be an empty tree if all subentries are i-t-a.
388                  */
389                 if (contains_ita && is_empty_tree_oid(oid))
390                         continue;
391
392                 strbuf_grow(&buffer, entlen + 100);
393                 strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');
394                 strbuf_add(&buffer, oid->hash, the_hash_algo->rawsz);
395
396 #if DEBUG
397                 fprintf(stderr, "cache-tree update-one %o %.*s\n",
398                         mode, entlen, path + baselen);
399 #endif
400         }
401
402         if (repair) {
403                 struct object_id oid;
404                 hash_object_file(buffer.buf, buffer.len, tree_type, &oid);
405                 if (has_object_file(&oid))
406                         oidcpy(&it->oid, &oid);
407                 else
408                         to_invalidate = 1;
409         } else if (dryrun) {
410                 hash_object_file(buffer.buf, buffer.len, tree_type, &it->oid);
411         } else if (write_object_file(buffer.buf, buffer.len, tree_type,
412                                      &it->oid)) {
413                 strbuf_release(&buffer);
414                 return -1;
415         }
416
417         strbuf_release(&buffer);
418         it->entry_count = to_invalidate ? -1 : i - *skip_count;
419 #if DEBUG
420         fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",
421                 it->entry_count, it->subtree_nr,
422                 oid_to_hex(&it->oid));
423 #endif
424         return i;
425 }
426
427 int cache_tree_update(struct index_state *istate, int flags)
428 {
429         struct cache_tree *it = istate->cache_tree;
430         struct cache_entry **cache = istate->cache;
431         int entries = istate->cache_nr;
432         int skip, i = verify_cache(cache, entries, flags);
433
434         if (i)
435                 return i;
436         i = update_one(it, cache, entries, "", 0, &skip, flags);
437         if (i < 0)
438                 return i;
439         istate->cache_changed |= CACHE_TREE_CHANGED;
440         return 0;
441 }
442
443 static void write_one(struct strbuf *buffer, struct cache_tree *it,
444                       const char *path, int pathlen)
445 {
446         int i;
447
448         /* One "cache-tree" entry consists of the following:
449          * path (NUL terminated)
450          * entry_count, subtree_nr ("%d %d\n")
451          * tree-sha1 (missing if invalid)
452          * subtree_nr "cache-tree" entries for subtrees.
453          */
454         strbuf_grow(buffer, pathlen + 100);
455         strbuf_add(buffer, path, pathlen);
456         strbuf_addf(buffer, "%c%d %d\n", 0, it->entry_count, it->subtree_nr);
457
458 #if DEBUG
459         if (0 <= it->entry_count)
460                 fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",
461                         pathlen, path, it->entry_count, it->subtree_nr,
462                         oid_to_hex(&it->oid));
463         else
464                 fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",
465                         pathlen, path, it->subtree_nr);
466 #endif
467
468         if (0 <= it->entry_count) {
469                 strbuf_add(buffer, it->oid.hash, the_hash_algo->rawsz);
470         }
471         for (i = 0; i < it->subtree_nr; i++) {
472                 struct cache_tree_sub *down = it->down[i];
473                 if (i) {
474                         struct cache_tree_sub *prev = it->down[i-1];
475                         if (subtree_name_cmp(down->name, down->namelen,
476                                              prev->name, prev->namelen) <= 0)
477                                 die("fatal - unsorted cache subtree");
478                 }
479                 write_one(buffer, down->cache_tree, down->name, down->namelen);
480         }
481 }
482
483 void cache_tree_write(struct strbuf *sb, struct cache_tree *root)
484 {
485         write_one(sb, root, "", 0);
486 }
487
488 static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
489 {
490         const char *buf = *buffer;
491         unsigned long size = *size_p;
492         const char *cp;
493         char *ep;
494         struct cache_tree *it;
495         int i, subtree_nr;
496         const unsigned rawsz = the_hash_algo->rawsz;
497
498         it = NULL;
499         /* skip name, but make sure name exists */
500         while (size && *buf) {
501                 size--;
502                 buf++;
503         }
504         if (!size)
505                 goto free_return;
506         buf++; size--;
507         it = cache_tree();
508
509         cp = buf;
510         it->entry_count = strtol(cp, &ep, 10);
511         if (cp == ep)
512                 goto free_return;
513         cp = ep;
514         subtree_nr = strtol(cp, &ep, 10);
515         if (cp == ep)
516                 goto free_return;
517         while (size && *buf && *buf != '\n') {
518                 size--;
519                 buf++;
520         }
521         if (!size)
522                 goto free_return;
523         buf++; size--;
524         if (0 <= it->entry_count) {
525                 if (size < rawsz)
526                         goto free_return;
527                 oidread(&it->oid, (const unsigned char *)buf);
528                 buf += rawsz;
529                 size -= rawsz;
530         }
531
532 #if DEBUG
533         if (0 <= it->entry_count)
534                 fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",
535                         *buffer, it->entry_count, subtree_nr,
536                         oid_to_hex(&it->oid));
537         else
538                 fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",
539                         *buffer, subtree_nr);
540 #endif
541
542         /*
543          * Just a heuristic -- we do not add directories that often but
544          * we do not want to have to extend it immediately when we do,
545          * hence +2.
546          */
547         it->subtree_alloc = subtree_nr + 2;
548         it->down = xcalloc(it->subtree_alloc, sizeof(struct cache_tree_sub *));
549         for (i = 0; i < subtree_nr; i++) {
550                 /* read each subtree */
551                 struct cache_tree *sub;
552                 struct cache_tree_sub *subtree;
553                 const char *name = buf;
554
555                 sub = read_one(&buf, &size);
556                 if (!sub)
557                         goto free_return;
558                 subtree = cache_tree_sub(it, name);
559                 subtree->cache_tree = sub;
560         }
561         if (subtree_nr != it->subtree_nr)
562                 die("cache-tree: internal error");
563         *buffer = buf;
564         *size_p = size;
565         return it;
566
567  free_return:
568         cache_tree_free(&it);
569         return NULL;
570 }
571
572 struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)
573 {
574         if (buffer[0])
575                 return NULL; /* not the whole tree */
576         return read_one(&buffer, &size);
577 }
578
579 static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *path)
580 {
581         if (!it)
582                 return NULL;
583         while (*path) {
584                 const char *slash;
585                 struct cache_tree_sub *sub;
586
587                 slash = strchrnul(path, '/');
588                 /*
589                  * Between path and slash is the name of the subtree
590                  * to look for.
591                  */
592                 sub = find_subtree(it, path, slash - path, 0);
593                 if (!sub)
594                         return NULL;
595                 it = sub->cache_tree;
596
597                 path = slash;
598                 while (*path == '/')
599                         path++;
600         }
601         return it;
602 }
603
604 int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
605 {
606         int entries, was_valid;
607         struct lock_file lock_file = LOCK_INIT;
608         int ret = 0;
609
610         hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);
611
612         entries = read_index_from(index_state, index_path, get_git_dir());
613         if (entries < 0) {
614                 ret = WRITE_TREE_UNREADABLE_INDEX;
615                 goto out;
616         }
617         if (flags & WRITE_TREE_IGNORE_CACHE_TREE)
618                 cache_tree_free(&index_state->cache_tree);
619
620         if (!index_state->cache_tree)
621                 index_state->cache_tree = cache_tree();
622
623         was_valid = cache_tree_fully_valid(index_state->cache_tree);
624         if (!was_valid) {
625                 if (cache_tree_update(index_state, flags) < 0) {
626                         ret = WRITE_TREE_UNMERGED_INDEX;
627                         goto out;
628                 }
629                 write_locked_index(index_state, &lock_file, COMMIT_LOCK);
630                 /* Not being able to write is fine -- we are only interested
631                  * in updating the cache-tree part, and if the next caller
632                  * ends up using the old index with unupdated cache-tree part
633                  * it misses the work we did here, but that is just a
634                  * performance penalty and not a big deal.
635                  */
636         }
637
638         if (prefix) {
639                 struct cache_tree *subtree;
640                 subtree = cache_tree_find(index_state->cache_tree, prefix);
641                 if (!subtree) {
642                         ret = WRITE_TREE_PREFIX_ERROR;
643                         goto out;
644                 }
645                 oidcpy(oid, &subtree->oid);
646         }
647         else
648                 oidcpy(oid, &index_state->cache_tree->oid);
649
650 out:
651         rollback_lock_file(&lock_file);
652         return ret;
653 }
654
655 static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
656 {
657         struct tree_desc desc;
658         struct name_entry entry;
659         int cnt;
660
661         oidcpy(&it->oid, &tree->object.oid);
662         init_tree_desc(&desc, tree->buffer, tree->size);
663         cnt = 0;
664         while (tree_entry(&desc, &entry)) {
665                 if (!S_ISDIR(entry.mode))
666                         cnt++;
667                 else {
668                         struct cache_tree_sub *sub;
669                         struct tree *subtree = lookup_tree(the_repository,
670                                                            entry.oid);
671                         if (!subtree->object.parsed)
672                                 parse_tree(subtree);
673                         sub = cache_tree_sub(it, entry.path);
674                         sub->cache_tree = cache_tree();
675                         prime_cache_tree_rec(sub->cache_tree, subtree);
676                         cnt += sub->cache_tree->entry_count;
677                 }
678         }
679         it->entry_count = cnt;
680 }
681
682 void prime_cache_tree(struct index_state *istate, struct tree *tree)
683 {
684         cache_tree_free(&istate->cache_tree);
685         istate->cache_tree = cache_tree();
686         prime_cache_tree_rec(istate->cache_tree, tree);
687         istate->cache_changed |= CACHE_TREE_CHANGED;
688 }
689
690 /*
691  * find the cache_tree that corresponds to the current level without
692  * exploding the full path into textual form.  The root of the
693  * cache tree is given as "root", and our current level is "info".
694  * (1) When at root level, info->prev is NULL, so it is "root" itself.
695  * (2) Otherwise, find the cache_tree that corresponds to one level
696  *     above us, and find ourselves in there.
697  */
698 static struct cache_tree *find_cache_tree_from_traversal(struct cache_tree *root,
699                                                          struct traverse_info *info)
700 {
701         struct cache_tree *our_parent;
702
703         if (!info->prev)
704                 return root;
705         our_parent = find_cache_tree_from_traversal(root, info->prev);
706         return cache_tree_find(our_parent, info->name.path);
707 }
708
709 int cache_tree_matches_traversal(struct cache_tree *root,
710                                  struct name_entry *ent,
711                                  struct traverse_info *info)
712 {
713         struct cache_tree *it;
714
715         it = find_cache_tree_from_traversal(root, info);
716         it = cache_tree_find(it, ent->path);
717         if (it && it->entry_count > 0 && !oidcmp(ent->oid, &it->oid))
718                 return it->entry_count;
719         return 0;
720 }