describe: do not silently ignore indescribable commits
[git/mingw.git] / read-tree.c
bloba46c6fe2f5d3234abe5dce0b7a9d44da07b6dae9
1 /*
2 * GIT - The information manager from hell
4 * Copyright (C) Linus Torvalds, 2005
5 */
6 #define DBRT_DEBUG 1
8 #include "cache.h"
10 #include "object.h"
11 #include "tree.h"
13 static int merge = 0;
14 static int update = 0;
15 static int index_only = 0;
16 static int nontrivial_merge = 0;
17 static int trivial_merges_only = 0;
19 static int head_idx = -1;
20 static int merge_size = 0;
22 static struct object_list *trees = NULL;
24 static struct cache_entry df_conflict_entry = {
27 static struct tree_entry_list df_conflict_list = {
28 .name = NULL,
29 .next = &df_conflict_list
32 typedef int (*merge_fn_t)(struct cache_entry **src);
34 static int entcmp(char *name1, int dir1, char *name2, int dir2)
36 int len1 = strlen(name1);
37 int len2 = strlen(name2);
38 int len = len1 < len2 ? len1 : len2;
39 int ret = memcmp(name1, name2, len);
40 unsigned char c1, c2;
41 if (ret)
42 return ret;
43 c1 = name1[len];
44 c2 = name2[len];
45 if (!c1 && dir1)
46 c1 = '/';
47 if (!c2 && dir2)
48 c2 = '/';
49 ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
50 if (c1 && c2 && !ret)
51 ret = len1 - len2;
52 return ret;
55 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
56 const char *base, merge_fn_t fn, int *indpos)
58 int baselen = strlen(base);
59 int src_size = len + 1;
60 do {
61 int i;
62 char *first;
63 int firstdir = 0;
64 int pathlen;
65 unsigned ce_size;
66 struct tree_entry_list **subposns;
67 struct cache_entry **src;
68 int any_files = 0;
69 int any_dirs = 0;
70 char *cache_name;
71 int ce_stage;
73 /* Find the first name in the input. */
75 first = NULL;
76 cache_name = NULL;
78 /* Check the cache */
79 if (merge && *indpos < active_nr) {
80 /* This is a bit tricky: */
81 /* If the index has a subdirectory (with
82 * contents) as the first name, it'll get a
83 * filename like "foo/bar". But that's after
84 * "foo", so the entry in trees will get
85 * handled first, at which point we'll go into
86 * "foo", and deal with "bar" from the index,
87 * because the base will be "foo/". The only
88 * way we can actually have "foo/bar" first of
89 * all the things is if the trees don't
90 * contain "foo" at all, in which case we'll
91 * handle "foo/bar" without going into the
92 * directory, but that's fine (and will return
93 * an error anyway, with the added unknown
94 * file case.
97 cache_name = active_cache[*indpos]->name;
98 if (strlen(cache_name) > baselen &&
99 !memcmp(cache_name, base, baselen)) {
100 cache_name += baselen;
101 first = cache_name;
102 } else {
103 cache_name = NULL;
107 #if DBRT_DEBUG > 1
108 if (first)
109 printf("index %s\n", first);
110 #endif
111 for (i = 0; i < len; i++) {
112 if (!posns[i] || posns[i] == &df_conflict_list)
113 continue;
114 #if DBRT_DEBUG > 1
115 printf("%d %s\n", i + 1, posns[i]->name);
116 #endif
117 if (!first || entcmp(first, firstdir,
118 posns[i]->name,
119 posns[i]->directory) > 0) {
120 first = posns[i]->name;
121 firstdir = posns[i]->directory;
124 /* No name means we're done */
125 if (!first)
126 return 0;
128 pathlen = strlen(first);
129 ce_size = cache_entry_size(baselen + pathlen);
131 src = xmalloc(sizeof(struct cache_entry *) * src_size);
132 memset(src, 0, sizeof(struct cache_entry *) * src_size);
134 subposns = xmalloc(sizeof(struct tree_list_entry *) * len);
135 memset(subposns, 0, sizeof(struct tree_list_entry *) * len);
137 if (cache_name && !strcmp(cache_name, first)) {
138 any_files = 1;
139 src[0] = active_cache[*indpos];
140 remove_cache_entry_at(*indpos);
143 for (i = 0; i < len; i++) {
144 struct cache_entry *ce;
146 if (!posns[i] ||
147 (posns[i] != &df_conflict_list &&
148 strcmp(first, posns[i]->name))) {
149 continue;
152 if (posns[i] == &df_conflict_list) {
153 src[i + merge] = &df_conflict_entry;
154 continue;
157 if (posns[i]->directory) {
158 any_dirs = 1;
159 parse_tree(posns[i]->item.tree);
160 subposns[i] = posns[i]->item.tree->entries;
161 posns[i] = posns[i]->next;
162 src[i + merge] = &df_conflict_entry;
163 continue;
166 if (!merge)
167 ce_stage = 0;
168 else if (i + 1 < head_idx)
169 ce_stage = 1;
170 else if (i + 1 > head_idx)
171 ce_stage = 3;
172 else
173 ce_stage = 2;
175 ce = xmalloc(ce_size);
176 memset(ce, 0, ce_size);
177 ce->ce_mode = create_ce_mode(posns[i]->mode);
178 ce->ce_flags = create_ce_flags(baselen + pathlen,
179 ce_stage);
180 memcpy(ce->name, base, baselen);
181 memcpy(ce->name + baselen, first, pathlen + 1);
183 any_files = 1;
185 memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
186 src[i + merge] = ce;
187 subposns[i] = &df_conflict_list;
188 posns[i] = posns[i]->next;
190 if (any_files) {
191 if (merge) {
192 int ret;
194 #if DBRT_DEBUG > 1
195 printf("%s:\n", first);
196 for (i = 0; i < src_size; i++) {
197 printf(" %d ", i);
198 if (src[i])
199 printf("%s\n", sha1_to_hex(src[i]->sha1));
200 else
201 printf("\n");
203 #endif
204 ret = fn(src);
206 #if DBRT_DEBUG > 1
207 printf("Added %d entries\n", ret);
208 #endif
209 *indpos += ret;
210 } else {
211 for (i = 0; i < src_size; i++) {
212 if (src[i]) {
213 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
218 if (any_dirs) {
219 char *newbase = xmalloc(baselen + 2 + pathlen);
220 memcpy(newbase, base, baselen);
221 memcpy(newbase + baselen, first, pathlen);
222 newbase[baselen + pathlen] = '/';
223 newbase[baselen + pathlen + 1] = '\0';
224 if (unpack_trees_rec(subposns, len, newbase, fn,
225 indpos))
226 return -1;
227 free(newbase);
229 free(subposns);
230 free(src);
231 } while (1);
234 static void reject_merge(struct cache_entry *ce)
236 die("Entry '%s' would be overwritten by merge. Cannot merge.",
237 ce->name);
240 /* Unlink the last component and attempt to remove leading
241 * directories, in case this unlink is the removal of the
242 * last entry in the directory -- empty directories are removed.
244 static void unlink_entry(char *name)
246 char *cp, *prev;
248 if (unlink(name))
249 return;
250 prev = NULL;
251 while (1) {
252 int status;
253 cp = strrchr(name, '/');
254 if (prev)
255 *prev = '/';
256 if (!cp)
257 break;
259 *cp = 0;
260 status = rmdir(name);
261 if (status) {
262 *cp = '/';
263 break;
265 prev = cp;
269 static void check_updates(struct cache_entry **src, int nr)
271 static struct checkout state = {
272 .base_dir = "",
273 .force = 1,
274 .quiet = 1,
275 .refresh_cache = 1,
277 unsigned short mask = htons(CE_UPDATE);
278 while (nr--) {
279 struct cache_entry *ce = *src++;
280 if (!ce->ce_mode) {
281 if (update)
282 unlink_entry(ce->name);
283 continue;
285 if (ce->ce_flags & mask) {
286 ce->ce_flags &= ~mask;
287 if (update)
288 checkout_entry(ce, &state);
293 static int unpack_trees(merge_fn_t fn)
295 int indpos = 0;
296 unsigned len = object_list_length(trees);
297 struct tree_entry_list **posns;
298 int i;
299 struct object_list *posn = trees;
300 merge_size = len;
302 if (len) {
303 posns = xmalloc(len * sizeof(struct tree_entry_list *));
304 for (i = 0; i < len; i++) {
305 posns[i] = ((struct tree *) posn->item)->entries;
306 posn = posn->next;
308 if (unpack_trees_rec(posns, len, "", fn, &indpos))
309 return -1;
312 if (trivial_merges_only && nontrivial_merge)
313 die("Merge requires file-level merging");
315 check_updates(active_cache, active_nr);
316 return 0;
319 static int list_tree(unsigned char *sha1)
321 struct tree *tree = parse_tree_indirect(sha1);
322 if (!tree)
323 return -1;
324 object_list_append(&tree->object, &trees);
325 return 0;
328 static int same(struct cache_entry *a, struct cache_entry *b)
330 if (!!a != !!b)
331 return 0;
332 if (!a && !b)
333 return 1;
334 return a->ce_mode == b->ce_mode &&
335 !memcmp(a->sha1, b->sha1, 20);
340 * When a CE gets turned into an unmerged entry, we
341 * want it to be up-to-date
343 static void verify_uptodate(struct cache_entry *ce)
345 struct stat st;
347 if (index_only)
348 return;
350 if (!lstat(ce->name, &st)) {
351 unsigned changed = ce_match_stat(ce, &st);
352 if (!changed)
353 return;
354 errno = 0;
356 if (errno == ENOENT)
357 return;
358 die("Entry '%s' not uptodate. Cannot merge.", ce->name);
361 static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
363 merge->ce_flags |= htons(CE_UPDATE);
364 if (old) {
366 * See if we can re-use the old CE directly?
367 * That way we get the uptodate stat info.
369 * This also removes the UPDATE flag on
370 * a match.
372 if (same(old, merge)) {
373 *merge = *old;
374 } else {
375 verify_uptodate(old);
378 merge->ce_flags &= ~htons(CE_STAGEMASK);
379 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
380 return 1;
383 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
385 if (old)
386 verify_uptodate(old);
387 ce->ce_mode = 0;
388 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
389 return 1;
392 static int keep_entry(struct cache_entry *ce)
394 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
395 return 1;
398 #if DBRT_DEBUG
399 static void show_stage_entry(FILE *o,
400 const char *label, const struct cache_entry *ce)
402 if (!ce)
403 fprintf(o, "%s (missing)\n", label);
404 else
405 fprintf(o, "%s%06o %s %d\t%s\n",
406 label,
407 ntohl(ce->ce_mode),
408 sha1_to_hex(ce->sha1),
409 ce_stage(ce),
410 ce->name);
412 #endif
414 static int threeway_merge(struct cache_entry **stages)
416 struct cache_entry *index;
417 struct cache_entry *head;
418 struct cache_entry *remote = stages[head_idx + 1];
419 int count;
420 int head_match = 0;
421 int remote_match = 0;
423 int df_conflict_head = 0;
424 int df_conflict_remote = 0;
426 int any_anc_missing = 0;
427 int i;
429 for (i = 1; i < head_idx; i++) {
430 if (!stages[i])
431 any_anc_missing = 1;
434 index = stages[0];
435 head = stages[head_idx];
437 if (head == &df_conflict_entry) {
438 df_conflict_head = 1;
439 head = NULL;
442 if (remote == &df_conflict_entry) {
443 df_conflict_remote = 1;
444 remote = NULL;
447 /* First, if there's a #16 situation, note that to prevent #13
448 * and #14.
450 if (!same(remote, head)) {
451 for (i = 1; i < head_idx; i++) {
452 if (same(stages[i], head)) {
453 head_match = i;
455 if (same(stages[i], remote)) {
456 remote_match = i;
461 /* We start with cases where the index is allowed to match
462 * something other than the head: #14(ALT) and #2ALT, where it
463 * is permitted to match the result instead.
465 /* #14, #14ALT, #2ALT */
466 if (remote && !df_conflict_head && head_match && !remote_match) {
467 if (index && !same(index, remote) && !same(index, head))
468 reject_merge(index);
469 return merged_entry(remote, index);
472 * If we have an entry in the index cache, then we want to
473 * make sure that it matches head.
475 if (index && !same(index, head)) {
476 reject_merge(index);
479 if (head) {
480 /* #5ALT, #15 */
481 if (same(head, remote))
482 return merged_entry(head, index);
483 /* #13, #3ALT */
484 if (!df_conflict_remote && remote_match && !head_match)
485 return merged_entry(head, index);
488 /* #1 */
489 if (!head && !remote && any_anc_missing)
490 return 0;
492 /* Below are "no merge" cases, which require that the index be
493 * up-to-date to avoid the files getting overwritten with
494 * conflict resolution files.
496 if (index) {
497 verify_uptodate(index);
500 nontrivial_merge = 1;
502 /* #2, #3, #4, #6, #7, #9, #11. */
503 count = 0;
504 if (!head_match || !remote_match) {
505 for (i = 1; i < head_idx; i++) {
506 if (stages[i]) {
507 keep_entry(stages[i]);
508 count++;
509 break;
513 #if DBRT_DEBUG
514 else {
515 fprintf(stderr, "read-tree: warning #16 detected\n");
516 show_stage_entry(stderr, "head ", stages[head_match]);
517 show_stage_entry(stderr, "remote ", stages[remote_match]);
519 #endif
520 if (head) { count += keep_entry(head); }
521 if (remote) { count += keep_entry(remote); }
522 return count;
526 * Two-way merge.
528 * The rule is to "carry forward" what is in the index without losing
529 * information across a "fast forward", favoring a successful merge
530 * over a merge failure when it makes sense. For details of the
531 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
534 static int twoway_merge(struct cache_entry **src)
536 struct cache_entry *current = src[0];
537 struct cache_entry *oldtree = src[1], *newtree = src[2];
539 if (merge_size != 2)
540 return error("Cannot do a twoway merge of %d trees\n",
541 merge_size);
543 if (current) {
544 if ((!oldtree && !newtree) || /* 4 and 5 */
545 (!oldtree && newtree &&
546 same(current, newtree)) || /* 6 and 7 */
547 (oldtree && newtree &&
548 same(oldtree, newtree)) || /* 14 and 15 */
549 (oldtree && newtree &&
550 !same(oldtree, newtree) && /* 18 and 19*/
551 same(current, newtree))) {
552 return keep_entry(current);
554 else if (oldtree && !newtree && same(current, oldtree)) {
555 /* 10 or 11 */
556 return deleted_entry(oldtree, current);
558 else if (oldtree && newtree &&
559 same(current, oldtree) && !same(current, newtree)) {
560 /* 20 or 21 */
561 return merged_entry(newtree, current);
563 else {
564 /* all other failures */
565 if (oldtree)
566 reject_merge(oldtree);
567 if (current)
568 reject_merge(current);
569 if (newtree)
570 reject_merge(newtree);
571 return -1;
574 else if (newtree)
575 return merged_entry(newtree, current);
576 else
577 return deleted_entry(oldtree, current);
581 * One-way merge.
583 * The rule is:
584 * - take the stat information from stage0, take the data from stage1
586 static int oneway_merge(struct cache_entry **src)
588 struct cache_entry *old = src[0];
589 struct cache_entry *a = src[1];
591 if (merge_size != 1)
592 return error("Cannot do a oneway merge of %d trees\n",
593 merge_size);
595 if (!a)
596 return 0;
597 if (old && same(old, a)) {
598 return keep_entry(old);
600 return merged_entry(a, NULL);
603 static int read_cache_unmerged(void)
605 int i, deleted;
606 struct cache_entry **dst;
608 read_cache();
609 dst = active_cache;
610 deleted = 0;
611 for (i = 0; i < active_nr; i++) {
612 struct cache_entry *ce = active_cache[i];
613 if (ce_stage(ce)) {
614 deleted++;
615 continue;
617 if (deleted)
618 *dst = ce;
619 dst++;
621 active_nr -= deleted;
622 return deleted;
625 static const char read_tree_usage[] = "git-read-tree (<sha> | -m [-u | -i] <sha1> [<sha2> [<sha3>]])";
627 static struct cache_file cache_file;
629 int main(int argc, char **argv)
631 int i, newfd, reset, stage = 0;
632 unsigned char sha1[20];
633 merge_fn_t fn = NULL;
635 setup_git_directory();
637 newfd = hold_index_file_for_update(&cache_file, get_index_file());
638 if (newfd < 0)
639 die("unable to create new cachefile");
641 git_config(git_default_config);
643 merge = 0;
644 reset = 0;
645 for (i = 1; i < argc; i++) {
646 const char *arg = argv[i];
648 /* "-u" means "update", meaning that a merge will update
649 * the working tree.
651 if (!strcmp(arg, "-u")) {
652 update = 1;
653 continue;
656 /* "-i" means "index only", meaning that a merge will
657 * not even look at the working tree.
659 if (!strcmp(arg, "-i")) {
660 index_only = 1;
661 continue;
664 /* This differs from "-m" in that we'll silently ignore unmerged entries */
665 if (!strcmp(arg, "--reset")) {
666 if (stage || merge)
667 usage(read_tree_usage);
668 reset = 1;
669 merge = 1;
670 stage = 1;
671 read_cache_unmerged();
672 continue;
675 if (!strcmp(arg, "--trivial")) {
676 trivial_merges_only = 1;
677 continue;
680 /* "-m" stands for "merge", meaning we start in stage 1 */
681 if (!strcmp(arg, "-m")) {
682 if (stage || merge)
683 usage(read_tree_usage);
684 if (read_cache_unmerged())
685 die("you need to resolve your current index first");
686 stage = 1;
687 merge = 1;
688 continue;
691 /* using -u and -i at the same time makes no sense */
692 if (1 < index_only + update)
693 usage(read_tree_usage);
695 if (get_sha1(arg, sha1) < 0)
696 usage(read_tree_usage);
697 if (list_tree(sha1) < 0)
698 die("failed to unpack tree object %s", arg);
699 stage++;
701 if ((update||index_only) && !merge)
702 usage(read_tree_usage);
704 if (merge) {
705 if (stage < 2)
706 die("just how do you expect me to merge %d trees?", stage-1);
707 switch (stage - 1) {
708 case 1:
709 fn = oneway_merge;
710 break;
711 case 2:
712 fn = twoway_merge;
713 break;
714 case 3:
715 fn = threeway_merge;
716 break;
717 default:
718 fn = threeway_merge;
719 break;
722 if (stage - 1 >= 3)
723 head_idx = stage - 2;
724 else
725 head_idx = 1;
728 unpack_trees(fn);
729 if (write_cache(newfd, active_cache, active_nr) ||
730 commit_index_file(&cache_file))
731 die("unable to write new index file");
732 return 0;