read-tree: teach 1 and 2 way merges about cache-tree.
[git/git.git] / cache-tree.c
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1#include "cache.h"
2#include "tree.h"
3#include "cache-tree.h"
4
5#define DEBUG 0
6
7struct cache_tree *cache_tree(void)
8{
9 struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));
10 it->entry_count = -1;
11 return it;
12}
13
bad68ec9 14void cache_tree_free(struct cache_tree **it_p)
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15{
16 int i;
bad68ec9 17 struct cache_tree *it = *it_p;
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18
19 if (!it)
20 return;
21 for (i = 0; i < it->subtree_nr; i++)
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22 if (it->down[i])
23 cache_tree_free(&it->down[i]->cache_tree);
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24 free(it->down);
25 free(it);
bad68ec9 26 *it_p = NULL;
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27}
28
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29static int subtree_name_cmp(const char *one, int onelen,
30 const char *two, int twolen)
31{
32 if (onelen < twolen)
33 return -1;
34 if (twolen < onelen)
35 return 1;
36 return memcmp(one, two, onelen);
37}
38
39static int subtree_pos(struct cache_tree *it, const char *path, int pathlen)
40{
41 struct cache_tree_sub **down = it->down;
42 int lo, hi;
43 lo = 0;
44 hi = it->subtree_nr;
45 while (lo < hi) {
46 int mi = (lo + hi) / 2;
47 struct cache_tree_sub *mdl = down[mi];
48 int cmp = subtree_name_cmp(path, pathlen,
49 mdl->name, mdl->namelen);
50 if (!cmp)
51 return mi;
52 if (cmp < 0)
53 hi = mi;
54 else
55 lo = mi + 1;
56 }
57 return -lo-1;
58}
59
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60static struct cache_tree_sub *find_subtree(struct cache_tree *it,
61 const char *path,
62 int pathlen,
63 int create)
64{
74986462 65 struct cache_tree_sub *down;
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66 int pos = subtree_pos(it, path, pathlen);
67 if (0 <= pos)
68 return it->down[pos];
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69 if (!create)
70 return NULL;
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71
72 pos = -pos-1;
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73 if (it->subtree_alloc <= it->subtree_nr) {
74 it->subtree_alloc = alloc_nr(it->subtree_alloc);
75 it->down = xrealloc(it->down, it->subtree_alloc *
76 sizeof(*it->down));
77 }
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78 it->subtree_nr++;
79
74986462 80 down = xmalloc(sizeof(*down) + pathlen + 1);
61fa3097 81 down->cache_tree = NULL;
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82 down->namelen = pathlen;
83 memcpy(down->name, path, pathlen);
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84 down->name[pathlen] = 0;
85
86 if (pos < it->subtree_nr)
87 memmove(it->down + pos + 1,
88 it->down + pos,
89 sizeof(down) * (it->subtree_nr - pos - 1));
90 it->down[pos] = down;
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91 return down;
92}
93
94void cache_tree_invalidate_path(struct cache_tree *it, const char *path)
95{
96 /* a/b/c
97 * ==> invalidate self
98 * ==> find "a", have it invalidate "b/c"
99 * a
100 * ==> invalidate self
101 * ==> if "a" exists as a subtree, remove it.
102 */
103 const char *slash;
104 int namelen;
105 struct cache_tree_sub *down;
106
107 if (!it)
108 return;
109 slash = strchr(path, '/');
110 it->entry_count = -1;
111 if (!slash) {
61fa3097 112 int pos;
74986462 113 namelen = strlen(path);
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114 pos = subtree_pos(it, path, namelen);
115 if (0 <= pos) {
116 cache_tree_free(&it->down[pos]->cache_tree);
117 free(it->down[pos]);
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118 /* 0 1 2 3 4 5
119 * ^ ^subtree_nr = 6
61fa3097 120 * pos
74986462 121 * move 4 and 5 up one place (2 entries)
61fa3097 122 * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
74986462 123 */
61fa3097 124 memmove(it->down+pos, it->down+pos+1,
74986462 125 sizeof(struct cache_tree_sub *) *
61fa3097 126 (it->subtree_nr - pos - 1));
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127 it->subtree_nr--;
128 }
129 return;
130 }
131 namelen = slash - path;
132 down = find_subtree(it, path, namelen, 0);
133 if (down)
134 cache_tree_invalidate_path(down->cache_tree, slash + 1);
135}
136
137static int verify_cache(struct cache_entry **cache,
138 int entries)
139{
140 int i, funny;
141
142 /* Verify that the tree is merged */
143 funny = 0;
144 for (i = 0; i < entries; i++) {
145 struct cache_entry *ce = cache[i];
146 if (ce_stage(ce)) {
147 if (10 < ++funny) {
148 fprintf(stderr, "...\n");
149 break;
150 }
151 fprintf(stderr, "%s: unmerged (%s)\n",
152 ce->name, sha1_to_hex(ce->sha1));
153 }
154 }
155 if (funny)
156 return -1;
157
158 /* Also verify that the cache does not have path and path/file
159 * at the same time. At this point we know the cache has only
160 * stage 0 entries.
161 */
162 funny = 0;
163 for (i = 0; i < entries - 1; i++) {
164 /* path/file always comes after path because of the way
165 * the cache is sorted. Also path can appear only once,
166 * which means conflicting one would immediately follow.
167 */
168 const char *this_name = cache[i]->name;
169 const char *next_name = cache[i+1]->name;
170 int this_len = strlen(this_name);
171 if (this_len < strlen(next_name) &&
172 strncmp(this_name, next_name, this_len) == 0 &&
173 next_name[this_len] == '/') {
174 if (10 < ++funny) {
175 fprintf(stderr, "...\n");
176 break;
177 }
178 fprintf(stderr, "You have both %s and %s\n",
179 this_name, next_name);
180 }
181 }
182 if (funny)
183 return -1;
184 return 0;
185}
186
187static void discard_unused_subtrees(struct cache_tree *it)
188{
189 struct cache_tree_sub **down = it->down;
190 int nr = it->subtree_nr;
191 int dst, src;
192 for (dst = src = 0; src < nr; src++) {
193 struct cache_tree_sub *s = down[src];
194 if (s->used)
195 down[dst++] = s;
196 else {
bad68ec9 197 cache_tree_free(&s->cache_tree);
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198 free(s);
199 it->subtree_nr--;
200 }
201 }
202}
203
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204int cache_tree_fully_valid(struct cache_tree *it)
205{
206 int i;
207 if (!it)
208 return 0;
209 if (it->entry_count < 0 || !has_sha1_file(it->sha1))
210 return 0;
211 for (i = 0; i < it->subtree_nr; i++) {
212 if (!cache_tree_fully_valid(it->down[i]->cache_tree))
213 return 0;
214 }
215 return 1;
216}
217
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218static int update_one(struct cache_tree *it,
219 struct cache_entry **cache,
220 int entries,
221 const char *base,
222 int baselen,
223 int missing_ok)
224{
225 unsigned long size, offset;
226 char *buffer;
227 int i;
228
dd0c34c4 229 if (0 <= it->entry_count && has_sha1_file(it->sha1))
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230 return it->entry_count;
231
232 /*
233 * We first scan for subtrees and update them; we start by
234 * marking existing subtrees -- the ones that are unmarked
235 * should not be in the result.
236 */
237 for (i = 0; i < it->subtree_nr; i++)
238 it->down[i]->used = 0;
239
240 /*
241 * Find the subtrees and update them.
242 */
243 for (i = 0; i < entries; i++) {
244 struct cache_entry *ce = cache[i];
245 struct cache_tree_sub *sub;
246 const char *path, *slash;
247 int pathlen, sublen, subcnt;
248
249 path = ce->name;
250 pathlen = ce_namelen(ce);
251 if (pathlen <= baselen || memcmp(base, path, baselen))
252 break; /* at the end of this level */
253
254 slash = strchr(path + baselen, '/');
255 if (!slash)
256 continue;
257 /*
258 * a/bbb/c (base = a/, slash = /c)
259 * ==>
260 * path+baselen = bbb/c, sublen = 3
261 */
262 sublen = slash - (path + baselen);
263 sub = find_subtree(it, path + baselen, sublen, 1);
264 if (!sub->cache_tree)
265 sub->cache_tree = cache_tree();
266 subcnt = update_one(sub->cache_tree,
267 cache + i, entries - i,
268 path,
269 baselen + sublen + 1,
270 missing_ok);
271 i += subcnt - 1;
272 sub->used = 1;
273 }
274
275 discard_unused_subtrees(it);
276
277 /*
278 * Then write out the tree object for this level.
279 */
280 size = 8192;
281 buffer = xmalloc(size);
282 offset = 0;
283
284 for (i = 0; i < entries; i++) {
285 struct cache_entry *ce = cache[i];
286 struct cache_tree_sub *sub;
287 const char *path, *slash;
288 int pathlen, entlen;
289 const unsigned char *sha1;
290 unsigned mode;
291
292 path = ce->name;
293 pathlen = ce_namelen(ce);
294 if (pathlen <= baselen || memcmp(base, path, baselen))
295 break; /* at the end of this level */
296
297 slash = strchr(path + baselen, '/');
298 if (slash) {
299 entlen = slash - (path + baselen);
300 sub = find_subtree(it, path + baselen, entlen, 0);
301 if (!sub)
302 die("cache-tree.c: '%.*s' in '%s' not found",
303 entlen, path + baselen, path);
304 i += sub->cache_tree->entry_count - 1;
305 sha1 = sub->cache_tree->sha1;
306 mode = S_IFDIR;
307 }
308 else {
309 sha1 = ce->sha1;
310 mode = ntohl(ce->ce_mode);
311 entlen = pathlen - baselen;
312 }
313 if (!missing_ok && !has_sha1_file(sha1))
314 return error("invalid object %s", sha1_to_hex(sha1));
315
316 if (!ce->ce_mode)
317 continue; /* entry being removed */
318
319 if (size < offset + entlen + 100) {
320 size = alloc_nr(offset + entlen + 100);
321 buffer = xrealloc(buffer, size);
322 }
323 offset += sprintf(buffer + offset,
324 "%o %.*s", mode, entlen, path + baselen);
325 buffer[offset++] = 0;
326 memcpy(buffer + offset, sha1, 20);
327 offset += 20;
328
329#if DEBUG
330 fprintf(stderr, "cache-tree %o %.*s\n",
331 mode, entlen, path + baselen);
332#endif
333 }
334
335 write_sha1_file(buffer, offset, tree_type, it->sha1);
336 free(buffer);
337 it->entry_count = i;
338#if DEBUG
339 fprintf(stderr, "cache-tree (%d ent, %d subtree) %s\n",
340 it->entry_count, it->subtree_nr,
341 sha1_to_hex(it->sha1));
342#endif
343 return i;
344}
345
346int cache_tree_update(struct cache_tree *it,
347 struct cache_entry **cache,
348 int entries,
349 int missing_ok)
350{
351 int i;
352 i = verify_cache(cache, entries);
353 if (i)
354 return i;
355 i = update_one(it, cache, entries, "", 0, missing_ok);
356 if (i < 0)
357 return i;
358 return 0;
359}
360
361static void *write_one(struct cache_tree *it,
362 char *path,
363 int pathlen,
364 char *buffer,
365 unsigned long *size,
366 unsigned long *offset)
367{
368 int i;
369
370 /* One "cache-tree" entry consists of the following:
371 * path (NUL terminated)
372 * entry_count, subtree_nr ("%d %d\n")
373 * tree-sha1 (missing if invalid)
374 * subtree_nr "cache-tree" entries for subtrees.
375 */
376 if (*size < *offset + pathlen + 100) {
377 *size = alloc_nr(*offset + pathlen + 100);
378 buffer = xrealloc(buffer, *size);
379 }
380 *offset += sprintf(buffer + *offset, "%.*s%c%d %d\n",
381 pathlen, path, 0,
382 it->entry_count, it->subtree_nr);
383
384#if DEBUG
385 if (0 <= it->entry_count)
386 fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",
387 pathlen, path, it->entry_count, it->subtree_nr,
388 sha1_to_hex(it->sha1));
389 else
390 fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",
391 pathlen, path, it->subtree_nr);
392#endif
393
394 if (0 <= it->entry_count) {
395 memcpy(buffer + *offset, it->sha1, 20);
396 *offset += 20;
397 }
398 for (i = 0; i < it->subtree_nr; i++) {
399 struct cache_tree_sub *down = it->down[i];
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400 if (i) {
401 struct cache_tree_sub *prev = it->down[i-1];
402 if (subtree_name_cmp(down->name, down->namelen,
403 prev->name, prev->namelen) <= 0)
404 die("fatal - unsorted cache subtree");
405 }
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406 buffer = write_one(down->cache_tree, down->name, down->namelen,
407 buffer, size, offset);
408 }
409 return buffer;
410}
411
bad68ec9 412void *cache_tree_write(struct cache_tree *root, unsigned long *size_p)
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413{
414 char path[PATH_MAX];
415 unsigned long size = 8192;
416 char *buffer = xmalloc(size);
417
bad68ec9 418 *size_p = 0;
74986462 419 path[0] = 0;
bad68ec9 420 return write_one(root, path, 0, buffer, &size, size_p);
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421}
422
423static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
424{
425 const char *buf = *buffer;
426 unsigned long size = *size_p;
427 struct cache_tree *it;
428 int i, subtree_nr;
429
430 it = NULL;
431 /* skip name, but make sure name exists */
432 while (size && *buf) {
433 size--;
434 buf++;
435 }
436 if (!size)
437 goto free_return;
438 buf++; size--;
439 it = cache_tree();
440 if (sscanf(buf, "%d %d\n", &it->entry_count, &subtree_nr) != 2)
441 goto free_return;
442 while (size && *buf && *buf != '\n') {
443 size--;
444 buf++;
445 }
446 if (!size)
447 goto free_return;
448 buf++; size--;
449 if (0 <= it->entry_count) {
450 if (size < 20)
451 goto free_return;
452 memcpy(it->sha1, buf, 20);
453 buf += 20;
454 size -= 20;
455 }
456
457#if DEBUG
458 if (0 <= it->entry_count)
459 fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",
460 *buffer, it->entry_count, subtree_nr,
461 sha1_to_hex(it->sha1));
462 else
463 fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",
464 *buffer, subtree_nr);
465#endif
466
467 /*
468 * Just a heuristic -- we do not add directories that often but
469 * we do not want to have to extend it immediately when we do,
470 * hence +2.
471 */
472 it->subtree_alloc = subtree_nr + 2;
473 it->down = xcalloc(it->subtree_alloc, sizeof(struct cache_tree_sub *));
474 for (i = 0; i < subtree_nr; i++) {
475 /* read each subtree */
476 struct cache_tree *sub;
61fa3097 477 struct cache_tree_sub *subtree;
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478 const char *name = buf;
479 int namelen;
480 sub = read_one(&buf, &size);
481 if (!sub)
482 goto free_return;
483 namelen = strlen(name);
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484 subtree = find_subtree(it, name, namelen, 1);
485 subtree->cache_tree = sub;
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486 }
487 if (subtree_nr != it->subtree_nr)
488 die("cache-tree: internal error");
489 *buffer = buf;
490 *size_p = size;
491 return it;
492
493 free_return:
bad68ec9 494 cache_tree_free(&it);
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495 return NULL;
496}
497
bad68ec9 498struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)
74986462 499{
bad68ec9 500 if (buffer[0])
74986462 501 return NULL; /* not the whole tree */
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502 return read_one(&buffer, &size);
503}