1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
6#define DBRT_DEBUG 1
7#include "cache.h"
9#include "object.h"
11#include "tree.h"
12#include <sys/time.h>
13#include <signal.h>
14static int reset = 0;
16static int merge = 0;
17static int update = 0;
18static int index_only = 0;
19static int nontrivial_merge = 0;
20static int trivial_merges_only = 0;
21static int aggressive = 0;
22static int verbose_update = 0;
23static volatile int progress_update = 0;
24static int head_idx = -1;
26static int merge_size = 0;
27static struct object_list *trees = NULL;
29static struct cache_entry df_conflict_entry = {
31};
32static struct tree_entry_list df_conflict_list = {
34 .name = NULL,
35 .next = &df_conflict_list
36};
37typedef int (*merge_fn_t)(struct cache_entry **src);
39static int entcmp(char *name1, int dir1, char *name2, int dir2)
41{
42 int len1 = strlen(name1);
43 int len2 = strlen(name2);
44 int len = len1 < len2 ? len1 : len2;
45 int ret = memcmp(name1, name2, len);
46 unsigned char c1, c2;
47 if (ret)
48 return ret;
49 c1 = name1[len];
50 c2 = name2[len];
51 if (!c1 && dir1)
52 c1 = '/';
53 if (!c2 && dir2)
54 c2 = '/';
55 ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
56 if (c1 && c2 && !ret)
57 ret = len1 - len2;
58 return ret;
59}
60static int unpack_trees_rec(struct tree_entry_list **posns, int len,
62 const char *base, merge_fn_t fn, int *indpos)
63{
64 int baselen = strlen(base);
65 int src_size = len + 1;
66 do {
67 int i;
68 char *first;
69 int firstdir = 0;
70 int pathlen;
71 unsigned ce_size;
72 struct tree_entry_list **subposns;
73 struct cache_entry **src;
74 int any_files = 0;
75 int any_dirs = 0;
76 char *cache_name;
77 int ce_stage;
78 /* Find the first name in the input. */
80 first = NULL;
82 cache_name = NULL;
83 /* Check the cache */
85 if (merge && *indpos < active_nr) {
86 /* This is a bit tricky: */
87 /* If the index has a subdirectory (with
88 * contents) as the first name, it'll get a
89 * filename like "foo/bar". But that's after
90 * "foo", so the entry in trees will get
91 * handled first, at which point we'll go into
92 * "foo", and deal with "bar" from the index,
93 * because the base will be "foo/". The only
94 * way we can actually have "foo/bar" first of
95 * all the things is if the trees don't
96 * contain "foo" at all, in which case we'll
97 * handle "foo/bar" without going into the
98 * directory, but that's fine (and will return
99 * an error anyway, with the added unknown
100 * file case.
101 */
102 cache_name = active_cache[*indpos]->name;
104 if (strlen(cache_name) > baselen &&
105 !memcmp(cache_name, base, baselen)) {
106 cache_name += baselen;
107 first = cache_name;
108 } else {
109 cache_name = NULL;
110 }
111 }
112#if DBRT_DEBUG > 1
114 if (first)
115 printf("index %s\n", first);
116#endif
117 for (i = 0; i < len; i++) {
118 if (!posns[i] || posns[i] == &df_conflict_list)
119 continue;
120#if DBRT_DEBUG > 1
121 printf("%d %s\n", i + 1, posns[i]->name);
122#endif
123 if (!first || entcmp(first, firstdir,
124 posns[i]->name,
125 posns[i]->directory) > 0) {
126 first = posns[i]->name;
127 firstdir = posns[i]->directory;
128 }
129 }
130 /* No name means we're done */
131 if (!first)
132 return 0;
133 pathlen = strlen(first);
135 ce_size = cache_entry_size(baselen + pathlen);
136 src = xcalloc(src_size, sizeof(struct cache_entry *));
138 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
140 if (cache_name && !strcmp(cache_name, first)) {
142 any_files = 1;
143 src[0] = active_cache[*indpos];
144 remove_cache_entry_at(*indpos);
145 }
146 for (i = 0; i < len; i++) {
148 struct cache_entry *ce;
149 if (!posns[i] ||
151 (posns[i] != &df_conflict_list &&
152 strcmp(first, posns[i]->name))) {
153 continue;
154 }
155 if (posns[i] == &df_conflict_list) {
157 src[i + merge] = &df_conflict_entry;
158 continue;
159 }
160 if (posns[i]->directory) {
162 any_dirs = 1;
163 parse_tree(posns[i]->item.tree);
164 subposns[i] = posns[i]->item.tree->entries;
165 posns[i] = posns[i]->next;
166 src[i + merge] = &df_conflict_entry;
167 continue;
168 }
169 if (!merge)
171 ce_stage = 0;
172 else if (i + 1 < head_idx)
173 ce_stage = 1;
174 else if (i + 1 > head_idx)
175 ce_stage = 3;
176 else
177 ce_stage = 2;
178 ce = xcalloc(1, ce_size);
180 ce->ce_mode = create_ce_mode(posns[i]->mode);
181 ce->ce_flags = create_ce_flags(baselen + pathlen,
182 ce_stage);
183 memcpy(ce->name, base, baselen);
184 memcpy(ce->name + baselen, first, pathlen + 1);
185 any_files = 1;
187 memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
189 src[i + merge] = ce;
190 subposns[i] = &df_conflict_list;
191 posns[i] = posns[i]->next;
192 }
193 if (any_files) {
194 if (merge) {
195 int ret;
196#if DBRT_DEBUG > 1
198 printf("%s:\n", first);
199 for (i = 0; i < src_size; i++) {
200 printf(" %d ", i);
201 if (src[i])
202 printf("%s\n", sha1_to_hex(src[i]->sha1));
203 else
204 printf("\n");
205 }
206#endif
207 ret = fn(src);
208
209#if DBRT_DEBUG > 1
210 printf("Added %d entries\n", ret);
211#endif
212 *indpos += ret;
213 } else {
214 for (i = 0; i < src_size; i++) {
215 if (src[i]) {
216 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
217 }
218 }
219 }
220 }
221 if (any_dirs) {
222 char *newbase = xmalloc(baselen + 2 + pathlen);
223 memcpy(newbase, base, baselen);
224 memcpy(newbase + baselen, first, pathlen);
225 newbase[baselen + pathlen] = '/';
226 newbase[baselen + pathlen + 1] = '\0';
227 if (unpack_trees_rec(subposns, len, newbase, fn,
228 indpos))
229 return -1;
230 free(newbase);
231 }
232 free(subposns);
233 free(src);
234 } while (1);
235}
236static void reject_merge(struct cache_entry *ce)
238{
239 die("Entry '%s' would be overwritten by merge. Cannot merge.",
240 ce->name);
241}
242/* Unlink the last component and attempt to remove leading
244 * directories, in case this unlink is the removal of the
245 * last entry in the directory -- empty directories are removed.
246 */
247static void unlink_entry(char *name)
248{
249 char *cp, *prev;
250 if (unlink(name))
252 return;
253 prev = NULL;
254 while (1) {
255 int status;
256 cp = strrchr(name, '/');
257 if (prev)
258 *prev = '/';
259 if (!cp)
260 break;
261 *cp = 0;
263 status = rmdir(name);
264 if (status) {
265 *cp = '/';
266 break;
267 }
268 prev = cp;
269 }
270}
271static void progress_interval(int signum)
273{
274 progress_update = 1;
275}
276static void setup_progress_signal(void)
278{
279 struct sigaction sa;
280 struct itimerval v;
281 memset(&sa, 0, sizeof(sa));
283 sa.sa_handler = progress_interval;
284 sigemptyset(&sa.sa_mask);
285 sa.sa_flags = SA_RESTART;
286 sigaction(SIGALRM, &sa, NULL);
287 v.it_interval.tv_sec = 1;
289 v.it_interval.tv_usec = 0;
290 v.it_value = v.it_interval;
291 setitimer(ITIMER_REAL, &v, NULL);
292}
293static void check_updates(struct cache_entry **src, int nr)
295{
296 static struct checkout state = {
297 .base_dir = "",
298 .force = 1,
299 .quiet = 1,
300 .refresh_cache = 1,
301 };
302 unsigned short mask = htons(CE_UPDATE);
303 unsigned last_percent = 200, cnt = 0, total = 0;
304 if (update && verbose_update) {
306 for (total = cnt = 0; cnt < nr; cnt++) {
307 struct cache_entry *ce = src[cnt];
308 if (!ce->ce_mode || ce->ce_flags & mask)
309 total++;
310 }
311 /* Don't bother doing this for very small updates */
313 if (total < 250)
314 total = 0;
315 if (total) {
317 fprintf(stderr, "Checking files out...\n");
318 setup_progress_signal();
319 progress_update = 1;
320 }
321 cnt = 0;
322 }
323 while (nr--) {
325 struct cache_entry *ce = *src++;
326 if (total) {
328 if (!ce->ce_mode || ce->ce_flags & mask) {
329 unsigned percent;
330 cnt++;
331 percent = (cnt * 100) / total;
332 if (percent != last_percent ||
333 progress_update) {
334 fprintf(stderr, "%4u%% (%u/%u) done\r",
335 percent, cnt, total);
336 last_percent = percent;
337 }
338 }
339 }
340 if (!ce->ce_mode) {
341 if (update)
342 unlink_entry(ce->name);
343 continue;
344 }
345 if (ce->ce_flags & mask) {
346 ce->ce_flags &= ~mask;
347 if (update)
348 checkout_entry(ce, &state, NULL);
349 }
350 }
351 if (total) {
352 signal(SIGALRM, SIG_IGN);
353 fputc('\n', stderr);
354 }
355}
356static int unpack_trees(merge_fn_t fn)
358{
359 int indpos = 0;
360 unsigned len = object_list_length(trees);
361 struct tree_entry_list **posns;
362 int i;
363 struct object_list *posn = trees;
364 merge_size = len;
365 if (len) {
367 posns = xmalloc(len * sizeof(struct tree_entry_list *));
368 for (i = 0; i < len; i++) {
369 posns[i] = ((struct tree *) posn->item)->entries;
370 posn = posn->next;
371 }
372 if (unpack_trees_rec(posns, len, "", fn, &indpos))
373 return -1;
374 }
375 if (trivial_merges_only && nontrivial_merge)
377 die("Merge requires file-level merging");
378 check_updates(active_cache, active_nr);
380 return 0;
381}
382static int list_tree(unsigned char *sha1)
384{
385 struct tree *tree = parse_tree_indirect(sha1);
386 if (!tree)
387 return -1;
388 object_list_append(&tree->object, &trees);
389 return 0;
390}
391static int same(struct cache_entry *a, struct cache_entry *b)
393{
394 if (!!a != !!b)
395 return 0;
396 if (!a && !b)
397 return 1;
398 return a->ce_mode == b->ce_mode &&
399 !memcmp(a->sha1, b->sha1, 20);
400}
401/*
404 * When a CE gets turned into an unmerged entry, we
405 * want it to be up-to-date
406 */
407static void verify_uptodate(struct cache_entry *ce)
408{
409 struct stat st;
410 if (index_only)
412 return;
413 if (!lstat(ce->name, &st)) {
415 unsigned changed = ce_match_stat(ce, &st, 1);
416 if (!changed)
417 return;
418 errno = 0;
419 }
420 if (reset) {
421 ce->ce_flags |= htons(CE_UPDATE);
422 return;
423 }
424 if (errno == ENOENT)
425 return;
426 die("Entry '%s' not uptodate. Cannot merge.", ce->name);
427}
428static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
430{
431 merge->ce_flags |= htons(CE_UPDATE);
432 if (old) {
433 /*
434 * See if we can re-use the old CE directly?
435 * That way we get the uptodate stat info.
436 *
437 * This also removes the UPDATE flag on
438 * a match.
439 */
440 if (same(old, merge)) {
441 *merge = *old;
442 } else {
443 verify_uptodate(old);
444 }
445 }
446 merge->ce_flags &= ~htons(CE_STAGEMASK);
447 add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
448 return 1;
449}
450static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
452{
453 if (old)
454 verify_uptodate(old);
455 ce->ce_mode = 0;
456 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
457 return 1;
458}
459static int keep_entry(struct cache_entry *ce)
461{
462 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
463 return 1;
464}
465#if DBRT_DEBUG
467static void show_stage_entry(FILE *o,
468 const char *label, const struct cache_entry *ce)
469{
470 if (!ce)
471 fprintf(o, "%s (missing)\n", label);
472 else
473 fprintf(o, "%s%06o %s %d\t%s\n",
474 label,
475 ntohl(ce->ce_mode),
476 sha1_to_hex(ce->sha1),
477 ce_stage(ce),
478 ce->name);
479}
480#endif
481static int threeway_merge(struct cache_entry **stages)
483{
484 struct cache_entry *index;
485 struct cache_entry *head;
486 struct cache_entry *remote = stages[head_idx + 1];
487 int count;
488 int head_match = 0;
489 int remote_match = 0;
490 int df_conflict_head = 0;
492 int df_conflict_remote = 0;
493 int any_anc_missing = 0;
495 int no_anc_exists = 1;
496 int i;
497 for (i = 1; i < head_idx; i++) {
499 if (!stages[i])
500 any_anc_missing = 1;
501 else
502 no_anc_exists = 0;
503 }
504 index = stages[0];
506 head = stages[head_idx];
507 if (head == &df_conflict_entry) {
509 df_conflict_head = 1;
510 head = NULL;
511 }
512 if (remote == &df_conflict_entry) {
514 df_conflict_remote = 1;
515 remote = NULL;
516 }
517 /* First, if there's a #16 situation, note that to prevent #13
519 * and #14.
520 */
521 if (!same(remote, head)) {
522 for (i = 1; i < head_idx; i++) {
523 if (same(stages[i], head)) {
524 head_match = i;
525 }
526 if (same(stages[i], remote)) {
527 remote_match = i;
528 }
529 }
530 }
531 /* We start with cases where the index is allowed to match
533 * something other than the head: #14(ALT) and #2ALT, where it
534 * is permitted to match the result instead.
535 */
536 /* #14, #14ALT, #2ALT */
537 if (remote && !df_conflict_head && head_match && !remote_match) {
538 if (index && !same(index, remote) && !same(index, head))
539 reject_merge(index);
540 return merged_entry(remote, index);
541 }
542 /*
543 * If we have an entry in the index cache, then we want to
544 * make sure that it matches head.
545 */
546 if (index && !same(index, head)) {
547 reject_merge(index);
548 }
549 if (head) {
551 /* #5ALT, #15 */
552 if (same(head, remote))
553 return merged_entry(head, index);
554 /* #13, #3ALT */
555 if (!df_conflict_remote && remote_match && !head_match)
556 return merged_entry(head, index);
557 }
558 /* #1 */
560 if (!head && !remote && any_anc_missing)
561 return 0;
562 /* Under the new "aggressive" rule, we resolve mostly trivial
564 * cases that we historically had git-merge-one-file resolve.
565 */
566 if (aggressive) {
567 int head_deleted = !head && !df_conflict_head;
568 int remote_deleted = !remote && !df_conflict_remote;
569 /*
570 * Deleted in both.
571 * Deleted in one and unchanged in the other.
572 */
573 if ((head_deleted && remote_deleted) ||
574 (head_deleted && remote && remote_match) ||
575 (remote_deleted && head && head_match)) {
576 if (index)
577 return deleted_entry(index, index);
578 return 0;
579 }
580 /*
581 * Added in both, identically.
582 */
583 if (no_anc_exists && head && remote && same(head, remote))
584 return merged_entry(head, index);
585 }
587 /* Below are "no merge" cases, which require that the index be
589 * up-to-date to avoid the files getting overwritten with
590 * conflict resolution files.
591 */
592 if (index) {
593 verify_uptodate(index);
594 }
595 nontrivial_merge = 1;
597 /* #2, #3, #4, #6, #7, #9, #11. */
599 count = 0;
600 if (!head_match || !remote_match) {
601 for (i = 1; i < head_idx; i++) {
602 if (stages[i]) {
603 keep_entry(stages[i]);
604 count++;
605 break;
606 }
607 }
608 }
609#if DBRT_DEBUG
610 else {
611 fprintf(stderr, "read-tree: warning #16 detected\n");
612 show_stage_entry(stderr, "head ", stages[head_match]);
613 show_stage_entry(stderr, "remote ", stages[remote_match]);
614 }
615#endif
616 if (head) { count += keep_entry(head); }
617 if (remote) { count += keep_entry(remote); }
618 return count;
619}
620/*
622 * Two-way merge.
623 *
624 * The rule is to "carry forward" what is in the index without losing
625 * information across a "fast forward", favoring a successful merge
626 * over a merge failure when it makes sense. For details of the
627 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
628 *
629 */
630static int twoway_merge(struct cache_entry **src)
631{
632 struct cache_entry *current = src[0];
633 struct cache_entry *oldtree = src[1], *newtree = src[2];
634 if (merge_size != 2)
636 return error("Cannot do a twoway merge of %d trees",
637 merge_size);
638 if (current) {
640 if ((!oldtree && !newtree) || /* 4 and 5 */
641 (!oldtree && newtree &&
642 same(current, newtree)) || /* 6 and 7 */
643 (oldtree && newtree &&
644 same(oldtree, newtree)) || /* 14 and 15 */
645 (oldtree && newtree &&
646 !same(oldtree, newtree) && /* 18 and 19*/
647 same(current, newtree))) {
648 return keep_entry(current);
649 }
650 else if (oldtree && !newtree && same(current, oldtree)) {
651 /* 10 or 11 */
652 return deleted_entry(oldtree, current);
653 }
654 else if (oldtree && newtree &&
655 same(current, oldtree) && !same(current, newtree)) {
656 /* 20 or 21 */
657 return merged_entry(newtree, current);
658 }
659 else {
660 /* all other failures */
661 if (oldtree)
662 reject_merge(oldtree);
663 if (current)
664 reject_merge(current);
665 if (newtree)
666 reject_merge(newtree);
667 return -1;
668 }
669 }
670 else if (newtree)
671 return merged_entry(newtree, current);
672 else
673 return deleted_entry(oldtree, current);
674}
675/*
677 * One-way merge.
678 *
679 * The rule is:
680 * - take the stat information from stage0, take the data from stage1
681 */
682static int oneway_merge(struct cache_entry **src)
683{
684 struct cache_entry *old = src[0];
685 struct cache_entry *a = src[1];
686 if (merge_size != 1)
688 return error("Cannot do a oneway merge of %d trees",
689 merge_size);
690 if (!a)
692 return deleted_entry(old, NULL);
693 if (old && same(old, a)) {
694 if (reset) {
695 struct stat st;
696 if (lstat(old->name, &st) ||
697 ce_match_stat(old, &st, 1))
698 old->ce_flags |= htons(CE_UPDATE);
699 }
700 return keep_entry(old);
701 }
702 return merged_entry(a, NULL);
703}
704static int read_cache_unmerged(void)
706{
707 int i, deleted;
708 struct cache_entry **dst;
709 read_cache();
711 dst = active_cache;
712 deleted = 0;
713 for (i = 0; i < active_nr; i++) {
714 struct cache_entry *ce = active_cache[i];
715 if (ce_stage(ce)) {
716 deleted++;
717 continue;
718 }
719 if (deleted)
720 *dst = ce;
721 dst++;
722 }
723 active_nr -= deleted;
724 return deleted;
725}
726static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
728static struct cache_file cache_file;
730int main(int argc, char **argv)
732{
733 int i, newfd, stage = 0;
734 unsigned char sha1[20];
735 merge_fn_t fn = NULL;
736 setup_git_directory();
738 git_config(git_default_config);
739 newfd = hold_index_file_for_update(&cache_file, get_index_file());
741 if (newfd < 0)
742 die("unable to create new cachefile");
743 git_config(git_default_config);
745 merge = 0;
747 reset = 0;
748 for (i = 1; i < argc; i++) {
749 const char *arg = argv[i];
750 /* "-u" means "update", meaning that a merge will update
752 * the working tree.
753 */
754 if (!strcmp(arg, "-u")) {
755 update = 1;
756 continue;
757 }
758 if (!strcmp(arg, "-v")) {
760 verbose_update = 1;
761 continue;
762 }
763 /* "-i" means "index only", meaning that a merge will
765 * not even look at the working tree.
766 */
767 if (!strcmp(arg, "-i")) {
768 index_only = 1;
769 continue;
770 }
771 /* This differs from "-m" in that we'll silently ignore unmerged entries */
773 if (!strcmp(arg, "--reset")) {
774 if (stage || merge)
775 usage(read_tree_usage);
776 reset = 1;
777 merge = 1;
778 stage = 1;
779 read_cache_unmerged();
780 continue;
781 }
782 if (!strcmp(arg, "--trivial")) {
784 trivial_merges_only = 1;
785 continue;
786 }
787 if (!strcmp(arg, "--aggressive")) {
789 aggressive = 1;
790 continue;
791 }
792 /* "-m" stands for "merge", meaning we start in stage 1 */
794 if (!strcmp(arg, "-m")) {
795 if (stage || merge)
796 usage(read_tree_usage);
797 if (read_cache_unmerged())
798 die("you need to resolve your current index first");
799 stage = 1;
800 merge = 1;
801 continue;
802 }
803 /* using -u and -i at the same time makes no sense */
805 if (1 < index_only + update)
806 usage(read_tree_usage);
807 if (get_sha1(arg, sha1))
809 die("Not a valid object name %s", arg);
810 if (list_tree(sha1) < 0)
811 die("failed to unpack tree object %s", arg);
812 stage++;
813 }
814 if ((update||index_only) && !merge)
815 usage(read_tree_usage);
816 if (merge) {
818 if (stage < 2)
819 die("just how do you expect me to merge %d trees?", stage-1);
820 switch (stage - 1) {
821 case 1:
822 fn = oneway_merge;
823 break;
824 case 2:
825 fn = twoway_merge;
826 break;
827 case 3:
828 fn = threeway_merge;
829 break;
830 default:
831 fn = threeway_merge;
832 break;
833 }
834 if (stage - 1 >= 3)
836 head_idx = stage - 2;
837 else
838 head_idx = 1;
839 }
840 unpack_trees(fn);
842 if (write_cache(newfd, active_cache, active_nr) ||
843 commit_index_file(&cache_file))
844 die("unable to write new index file");
845 return 0;
846}