Documentation: Transplanting branch with git-rebase --onto
[git] / cache-tree.c
1 #include "cache.h"
2 #include "tree.h"
3 #include "cache-tree.h"
4
5 #ifndef DEBUG
6 #define DEBUG 0
7 #endif
8
9 struct cache_tree *cache_tree(void)
10 {
11         struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));
12         it->entry_count = -1;
13         return it;
14 }
15
16 void cache_tree_free(struct cache_tree **it_p)
17 {
18         int i;
19         struct cache_tree *it = *it_p;
20
21         if (!it)
22                 return;
23         for (i = 0; i < it->subtree_nr; i++)
24                 if (it->down[i])
25                         cache_tree_free(&it->down[i]->cache_tree);
26         free(it->down);
27         free(it);
28         *it_p = NULL;
29 }
30
31 static int subtree_name_cmp(const char *one, int onelen,
32                             const char *two, int twolen)
33 {
34         if (onelen < twolen)
35                 return -1;
36         if (twolen < onelen)
37                 return 1;
38         return memcmp(one, two, onelen);
39 }
40
41 static int subtree_pos(struct cache_tree *it, const char *path, int pathlen)
42 {
43         struct cache_tree_sub **down = it->down;
44         int lo, hi;
45         lo = 0;
46         hi = it->subtree_nr;
47         while (lo < hi) {
48                 int mi = (lo + hi) / 2;
49                 struct cache_tree_sub *mdl = down[mi];
50                 int cmp = subtree_name_cmp(path, pathlen,
51                                            mdl->name, mdl->namelen);
52                 if (!cmp)
53                         return mi;
54                 if (cmp < 0)
55                         hi = mi;
56                 else
57                         lo = mi + 1;
58         }
59         return -lo-1;
60 }
61
62 static struct cache_tree_sub *find_subtree(struct cache_tree *it,
63                                            const char *path,
64                                            int pathlen,
65                                            int create)
66 {
67         struct cache_tree_sub *down;
68         int pos = subtree_pos(it, path, pathlen);
69         if (0 <= pos)
70                 return it->down[pos];
71         if (!create)
72                 return NULL;
73
74         pos = -pos-1;
75         if (it->subtree_alloc <= it->subtree_nr) {
76                 it->subtree_alloc = alloc_nr(it->subtree_alloc);
77                 it->down = xrealloc(it->down, it->subtree_alloc *
78                                     sizeof(*it->down));
79         }
80         it->subtree_nr++;
81
82         down = xmalloc(sizeof(*down) + pathlen + 1);
83         down->cache_tree = NULL;
84         down->namelen = pathlen;
85         memcpy(down->name, path, pathlen);
86         down->name[pathlen] = 0;
87
88         if (pos < it->subtree_nr)
89                 memmove(it->down + pos + 1,
90                         it->down + pos,
91                         sizeof(down) * (it->subtree_nr - pos - 1));
92         it->down[pos] = down;
93         return down;
94 }
95
96 struct cache_tree_sub *cache_tree_sub(struct cache_tree *it, const char *path)
97 {
98         int pathlen = strlen(path);
99         return find_subtree(it, path, pathlen, 1);
100 }
101
102 void cache_tree_invalidate_path(struct cache_tree *it, const char *path)
103 {
104         /* a/b/c
105          * ==> invalidate self
106          * ==> find "a", have it invalidate "b/c"
107          * a
108          * ==> invalidate self
109          * ==> if "a" exists as a subtree, remove it.
110          */
111         const char *slash;
112         int namelen;
113         struct cache_tree_sub *down;
114
115 #if DEBUG
116         fprintf(stderr, "cache-tree invalidate <%s>\n", path);
117 #endif
118
119         if (!it)
120                 return;
121         slash = strchr(path, '/');
122         it->entry_count = -1;
123         if (!slash) {
124                 int pos;
125                 namelen = strlen(path);
126                 pos = subtree_pos(it, path, namelen);
127                 if (0 <= pos) {
128                         cache_tree_free(&it->down[pos]->cache_tree);
129                         free(it->down[pos]);
130                         /* 0 1 2 3 4 5
131                          *       ^     ^subtree_nr = 6
132                          *       pos
133                          * move 4 and 5 up one place (2 entries)
134                          * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
135                          */
136                         memmove(it->down+pos, it->down+pos+1,
137                                 sizeof(struct cache_tree_sub *) *
138                                 (it->subtree_nr - pos - 1));
139                         it->subtree_nr--;
140                 }
141                 return;
142         }
143         namelen = slash - path;
144         down = find_subtree(it, path, namelen, 0);
145         if (down)
146                 cache_tree_invalidate_path(down->cache_tree, slash + 1);
147 }
148
149 static int verify_cache(struct cache_entry **cache,
150                         int entries)
151 {
152         int i, funny;
153
154         /* Verify that the tree is merged */
155         funny = 0;
156         for (i = 0; i < entries; i++) {
157                 struct cache_entry *ce = cache[i];
158                 if (ce_stage(ce)) {
159                         if (10 < ++funny) {
160                                 fprintf(stderr, "...\n");
161                                 break;
162                         }
163                         fprintf(stderr, "%s: unmerged (%s)\n",
164                                 ce->name, sha1_to_hex(ce->sha1));
165                 }
166         }
167         if (funny)
168                 return -1;
169
170         /* Also verify that the cache does not have path and path/file
171          * at the same time.  At this point we know the cache has only
172          * stage 0 entries.
173          */
174         funny = 0;
175         for (i = 0; i < entries - 1; i++) {
176                 /* path/file always comes after path because of the way
177                  * the cache is sorted.  Also path can appear only once,
178                  * which means conflicting one would immediately follow.
179                  */
180                 const char *this_name = cache[i]->name;
181                 const char *next_name = cache[i+1]->name;
182                 int this_len = strlen(this_name);
183                 if (this_len < strlen(next_name) &&
184                     strncmp(this_name, next_name, this_len) == 0 &&
185                     next_name[this_len] == '/') {
186                         if (10 < ++funny) {
187                                 fprintf(stderr, "...\n");
188                                 break;
189                         }
190                         fprintf(stderr, "You have both %s and %s\n",
191                                 this_name, next_name);
192                 }
193         }
194         if (funny)
195                 return -1;
196         return 0;
197 }
198
199 static void discard_unused_subtrees(struct cache_tree *it)
200 {
201         struct cache_tree_sub **down = it->down;
202         int nr = it->subtree_nr;
203         int dst, src;
204         for (dst = src = 0; src < nr; src++) {
205                 struct cache_tree_sub *s = down[src];
206                 if (s->used)
207                         down[dst++] = s;
208                 else {
209                         cache_tree_free(&s->cache_tree);
210                         free(s);
211                         it->subtree_nr--;
212                 }
213         }
214 }
215
216 int cache_tree_fully_valid(struct cache_tree *it)
217 {
218         int i;
219         if (!it)
220                 return 0;
221         if (it->entry_count < 0 || !has_sha1_file(it->sha1))
222                 return 0;
223         for (i = 0; i < it->subtree_nr; i++) {
224                 if (!cache_tree_fully_valid(it->down[i]->cache_tree))
225                         return 0;
226         }
227         return 1;
228 }
229
230 static int update_one(struct cache_tree *it,
231                       struct cache_entry **cache,
232                       int entries,
233                       const char *base,
234                       int baselen,
235                       int missing_ok,
236                       int dryrun)
237 {
238         unsigned long size, offset;
239         char *buffer;
240         int i;
241
242         if (0 <= it->entry_count && has_sha1_file(it->sha1))
243                 return it->entry_count;
244
245         /*
246          * We first scan for subtrees and update them; we start by
247          * marking existing subtrees -- the ones that are unmarked
248          * should not be in the result.
249          */
250         for (i = 0; i < it->subtree_nr; i++)
251                 it->down[i]->used = 0;
252
253         /*
254          * Find the subtrees and update them.
255          */
256         for (i = 0; i < entries; i++) {
257                 struct cache_entry *ce = cache[i];
258                 struct cache_tree_sub *sub;
259                 const char *path, *slash;
260                 int pathlen, sublen, subcnt;
261
262                 path = ce->name;
263                 pathlen = ce_namelen(ce);
264                 if (pathlen <= baselen || memcmp(base, path, baselen))
265                         break; /* at the end of this level */
266
267                 slash = strchr(path + baselen, '/');
268                 if (!slash)
269                         continue;
270                 /*
271                  * a/bbb/c (base = a/, slash = /c)
272                  * ==>
273                  * path+baselen = bbb/c, sublen = 3
274                  */
275                 sublen = slash - (path + baselen);
276                 sub = find_subtree(it, path + baselen, sublen, 1);
277                 if (!sub->cache_tree)
278                         sub->cache_tree = cache_tree();
279                 subcnt = update_one(sub->cache_tree,
280                                     cache + i, entries - i,
281                                     path,
282                                     baselen + sublen + 1,
283                                     missing_ok,
284                                     dryrun);
285                 i += subcnt - 1;
286                 sub->used = 1;
287         }
288
289         discard_unused_subtrees(it);
290
291         /*
292          * Then write out the tree object for this level.
293          */
294         size = 8192;
295         buffer = xmalloc(size);
296         offset = 0;
297
298         for (i = 0; i < entries; i++) {
299                 struct cache_entry *ce = cache[i];
300                 struct cache_tree_sub *sub;
301                 const char *path, *slash;
302                 int pathlen, entlen;
303                 const unsigned char *sha1;
304                 unsigned mode;
305
306                 path = ce->name;
307                 pathlen = ce_namelen(ce);
308                 if (pathlen <= baselen || memcmp(base, path, baselen))
309                         break; /* at the end of this level */
310
311                 slash = strchr(path + baselen, '/');
312                 if (slash) {
313                         entlen = slash - (path + baselen);
314                         sub = find_subtree(it, path + baselen, entlen, 0);
315                         if (!sub)
316                                 die("cache-tree.c: '%.*s' in '%s' not found",
317                                     entlen, path + baselen, path);
318                         i += sub->cache_tree->entry_count - 1;
319                         sha1 = sub->cache_tree->sha1;
320                         mode = S_IFDIR;
321                 }
322                 else {
323                         sha1 = ce->sha1;
324                         mode = ntohl(ce->ce_mode);
325                         entlen = pathlen - baselen;
326                 }
327                 if (!missing_ok && !has_sha1_file(sha1))
328                         return error("invalid object %s", sha1_to_hex(sha1));
329
330                 if (!ce->ce_mode)
331                         continue; /* entry being removed */
332
333                 if (size < offset + entlen + 100) {
334                         size = alloc_nr(offset + entlen + 100);
335                         buffer = xrealloc(buffer, size);
336                 }
337                 offset += sprintf(buffer + offset,
338                                   "%o %.*s", mode, entlen, path + baselen);
339                 buffer[offset++] = 0;
340                 hashcpy((unsigned char*)buffer + offset, sha1);
341                 offset += 20;
342
343 #if DEBUG
344                 fprintf(stderr, "cache-tree update-one %o %.*s\n",
345                         mode, entlen, path + baselen);
346 #endif
347         }
348
349         if (dryrun)
350                 hash_sha1_file(buffer, offset, tree_type, it->sha1);
351         else
352                 write_sha1_file(buffer, offset, tree_type, it->sha1);
353         free(buffer);
354         it->entry_count = i;
355 #if DEBUG
356         fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",
357                 it->entry_count, it->subtree_nr,
358                 sha1_to_hex(it->sha1));
359 #endif
360         return i;
361 }
362
363 int cache_tree_update(struct cache_tree *it,
364                       struct cache_entry **cache,
365                       int entries,
366                       int missing_ok,
367                       int dryrun)
368 {
369         int i;
370         i = verify_cache(cache, entries);
371         if (i)
372                 return i;
373         i = update_one(it, cache, entries, "", 0, missing_ok, dryrun);
374         if (i < 0)
375                 return i;
376         return 0;
377 }
378
379 static void *write_one(struct cache_tree *it,
380                        char *path,
381                        int pathlen,
382                        char *buffer,
383                        unsigned long *size,
384                        unsigned long *offset)
385 {
386         int i;
387
388         /* One "cache-tree" entry consists of the following:
389          * path (NUL terminated)
390          * entry_count, subtree_nr ("%d %d\n")
391          * tree-sha1 (missing if invalid)
392          * subtree_nr "cache-tree" entries for subtrees.
393          */
394         if (*size < *offset + pathlen + 100) {
395                 *size = alloc_nr(*offset + pathlen + 100);
396                 buffer = xrealloc(buffer, *size);
397         }
398         *offset += sprintf(buffer + *offset, "%.*s%c%d %d\n",
399                            pathlen, path, 0,
400                            it->entry_count, it->subtree_nr);
401
402 #if DEBUG
403         if (0 <= it->entry_count)
404                 fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",
405                         pathlen, path, it->entry_count, it->subtree_nr,
406                         sha1_to_hex(it->sha1));
407         else
408                 fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",
409                         pathlen, path, it->subtree_nr);
410 #endif
411
412         if (0 <= it->entry_count) {
413                 hashcpy((unsigned char*)buffer + *offset, it->sha1);
414                 *offset += 20;
415         }
416         for (i = 0; i < it->subtree_nr; i++) {
417                 struct cache_tree_sub *down = it->down[i];
418                 if (i) {
419                         struct cache_tree_sub *prev = it->down[i-1];
420                         if (subtree_name_cmp(down->name, down->namelen,
421                                              prev->name, prev->namelen) <= 0)
422                                 die("fatal - unsorted cache subtree");
423                 }
424                 buffer = write_one(down->cache_tree, down->name, down->namelen,
425                                    buffer, size, offset);
426         }
427         return buffer;
428 }
429
430 void *cache_tree_write(struct cache_tree *root, unsigned long *size_p)
431 {
432         char path[PATH_MAX];
433         unsigned long size = 8192;
434         char *buffer = xmalloc(size);
435
436         *size_p = 0;
437         path[0] = 0;
438         return write_one(root, path, 0, buffer, &size, size_p);
439 }
440
441 static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
442 {
443         const char *buf = *buffer;
444         unsigned long size = *size_p;
445         const char *cp;
446         char *ep;
447         struct cache_tree *it;
448         int i, subtree_nr;
449
450         it = NULL;
451         /* skip name, but make sure name exists */
452         while (size && *buf) {
453                 size--;
454                 buf++;
455         }
456         if (!size)
457                 goto free_return;
458         buf++; size--;
459         it = cache_tree();
460
461         cp = buf;
462         it->entry_count = strtol(cp, &ep, 10);
463         if (cp == ep)
464                 goto free_return;
465         cp = ep;
466         subtree_nr = strtol(cp, &ep, 10);
467         if (cp == ep)
468                 goto free_return;
469         while (size && *buf && *buf != '\n') {
470                 size--;
471                 buf++;
472         }
473         if (!size)
474                 goto free_return;
475         buf++; size--;
476         if (0 <= it->entry_count) {
477                 if (size < 20)
478                         goto free_return;
479                 hashcpy(it->sha1, (unsigned char*)buf);
480                 buf += 20;
481                 size -= 20;
482         }
483
484 #if DEBUG
485         if (0 <= it->entry_count)
486                 fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",
487                         *buffer, it->entry_count, subtree_nr,
488                         sha1_to_hex(it->sha1));
489         else
490                 fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",
491                         *buffer, subtree_nr);
492 #endif
493
494         /*
495          * Just a heuristic -- we do not add directories that often but
496          * we do not want to have to extend it immediately when we do,
497          * hence +2.
498          */
499         it->subtree_alloc = subtree_nr + 2;
500         it->down = xcalloc(it->subtree_alloc, sizeof(struct cache_tree_sub *));
501         for (i = 0; i < subtree_nr; i++) {
502                 /* read each subtree */
503                 struct cache_tree *sub;
504                 struct cache_tree_sub *subtree;
505                 const char *name = buf;
506
507                 sub = read_one(&buf, &size);
508                 if (!sub)
509                         goto free_return;
510                 subtree = cache_tree_sub(it, name);
511                 subtree->cache_tree = sub;
512         }
513         if (subtree_nr != it->subtree_nr)
514                 die("cache-tree: internal error");
515         *buffer = buf;
516         *size_p = size;
517         return it;
518
519  free_return:
520         cache_tree_free(&it);
521         return NULL;
522 }
523
524 struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)
525 {
526         if (buffer[0])
527                 return NULL; /* not the whole tree */
528         return read_one(&buffer, &size);
529 }
530
531 struct cache_tree *cache_tree_find(struct cache_tree *it, const char *path)
532 {
533         while (*path) {
534                 const char *slash;
535                 struct cache_tree_sub *sub;
536
537                 slash = strchr(path, '/');
538                 if (!slash)
539                         slash = path + strlen(path);
540                 /* between path and slash is the name of the
541                  * subtree to look for.
542                  */
543                 sub = find_subtree(it, path, slash - path, 0);
544                 if (!sub)
545                         return NULL;
546                 it = sub->cache_tree;
547                 if (slash)
548                         while (*slash && *slash == '/')
549                                 slash++;
550                 if (!slash || !*slash)
551                         return it; /* prefix ended with slashes */
552                 path = slash;
553         }
554         return it;
555 }