Merge branch 'js/mingw-rename-fix'
[git] / builtin-merge.c
1 /*
2  * Builtin "git merge"
3  *
4  * Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
5  *
6  * Based on git-merge.sh by Junio C Hamano.
7  */
8
9 #include "cache.h"
10 #include "parse-options.h"
11 #include "builtin.h"
12 #include "run-command.h"
13 #include "diff.h"
14 #include "refs.h"
15 #include "commit.h"
16 #include "diffcore.h"
17 #include "revision.h"
18 #include "unpack-trees.h"
19 #include "cache-tree.h"
20 #include "dir.h"
21 #include "utf8.h"
22 #include "log-tree.h"
23 #include "color.h"
24 #include "rerere.h"
25 #include "help.h"
26 #include "merge-recursive.h"
27
28 #define DEFAULT_TWOHEAD (1<<0)
29 #define DEFAULT_OCTOPUS (1<<1)
30 #define NO_FAST_FORWARD (1<<2)
31 #define NO_TRIVIAL      (1<<3)
32
33 struct strategy {
34         const char *name;
35         unsigned attr;
36 };
37
38 static const char * const builtin_merge_usage[] = {
39         "git-merge [options] <remote>...",
40         "git-merge [options] <msg> HEAD <remote>",
41         NULL
42 };
43
44 static int show_diffstat = 1, option_log, squash;
45 static int option_commit = 1, allow_fast_forward = 1;
46 static int allow_trivial = 1, have_message;
47 static struct strbuf merge_msg;
48 static struct commit_list *remoteheads;
49 static unsigned char head[20], stash[20];
50 static struct strategy **use_strategies;
51 static size_t use_strategies_nr, use_strategies_alloc;
52 static const char *branch;
53 static int verbosity;
54
55 static struct strategy all_strategy[] = {
56         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
57         { "octopus",    DEFAULT_OCTOPUS },
58         { "resolve",    0 },
59         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
60         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
61 };
62
63 static const char *pull_twohead, *pull_octopus;
64
65 static int option_parse_message(const struct option *opt,
66                                 const char *arg, int unset)
67 {
68         struct strbuf *buf = opt->value;
69
70         if (unset)
71                 strbuf_setlen(buf, 0);
72         else if (arg) {
73                 strbuf_addf(buf, "%s\n\n", arg);
74                 have_message = 1;
75         } else
76                 return error("switch `m' requires a value");
77         return 0;
78 }
79
80 static struct strategy *get_strategy(const char *name)
81 {
82         int i;
83         struct strategy *ret;
84         static struct cmdnames main_cmds, other_cmds;
85         static int loaded;
86
87         if (!name)
88                 return NULL;
89
90         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
91                 if (!strcmp(name, all_strategy[i].name))
92                         return &all_strategy[i];
93
94         if (!loaded) {
95                 struct cmdnames not_strategies;
96                 loaded = 1;
97
98                 memset(&not_strategies, 0, sizeof(struct cmdnames));
99                 load_command_list("git-merge-", &main_cmds, &other_cmds);
100                 for (i = 0; i < main_cmds.cnt; i++) {
101                         int j, found = 0;
102                         struct cmdname *ent = main_cmds.names[i];
103                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
104                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
105                                                 && !all_strategy[j].name[ent->len])
106                                         found = 1;
107                         if (!found)
108                                 add_cmdname(&not_strategies, ent->name, ent->len);
109                         exclude_cmds(&main_cmds, &not_strategies);
110                 }
111         }
112         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
113                 fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
114                 fprintf(stderr, "Available strategies are:");
115                 for (i = 0; i < main_cmds.cnt; i++)
116                         fprintf(stderr, " %s", main_cmds.names[i]->name);
117                 fprintf(stderr, ".\n");
118                 if (other_cmds.cnt) {
119                         fprintf(stderr, "Available custom strategies are:");
120                         for (i = 0; i < other_cmds.cnt; i++)
121                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
122                         fprintf(stderr, ".\n");
123                 }
124                 exit(1);
125         }
126
127         ret = xcalloc(1, sizeof(struct strategy));
128         ret->name = xstrdup(name);
129         return ret;
130 }
131
132 static void append_strategy(struct strategy *s)
133 {
134         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
135         use_strategies[use_strategies_nr++] = s;
136 }
137
138 static int option_parse_strategy(const struct option *opt,
139                                  const char *name, int unset)
140 {
141         if (unset)
142                 return 0;
143
144         append_strategy(get_strategy(name));
145         return 0;
146 }
147
148 static int option_parse_n(const struct option *opt,
149                           const char *arg, int unset)
150 {
151         show_diffstat = unset;
152         return 0;
153 }
154
155 static struct option builtin_merge_options[] = {
156         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
157                 "do not show a diffstat at the end of the merge",
158                 PARSE_OPT_NOARG, option_parse_n },
159         OPT_BOOLEAN(0, "stat", &show_diffstat,
160                 "show a diffstat at the end of the merge"),
161         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
162         OPT_BOOLEAN(0, "log", &option_log,
163                 "add list of one-line log to merge commit message"),
164         OPT_BOOLEAN(0, "squash", &squash,
165                 "create a single commit instead of doing a merge"),
166         OPT_BOOLEAN(0, "commit", &option_commit,
167                 "perform a commit if the merge succeeds (default)"),
168         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
169                 "allow fast forward (default)"),
170         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
171                 "merge strategy to use", option_parse_strategy),
172         OPT_CALLBACK('m', "message", &merge_msg, "message",
173                 "message to be used for the merge commit (if any)",
174                 option_parse_message),
175         OPT__VERBOSITY(&verbosity),
176         OPT_END()
177 };
178
179 /* Cleans up metadata that is uninteresting after a succeeded merge. */
180 static void drop_save(void)
181 {
182         unlink(git_path("MERGE_HEAD"));
183         unlink(git_path("MERGE_MSG"));
184         unlink(git_path("MERGE_MODE"));
185 }
186
187 static void save_state(void)
188 {
189         int len;
190         struct child_process cp;
191         struct strbuf buffer = STRBUF_INIT;
192         const char *argv[] = {"stash", "create", NULL};
193
194         memset(&cp, 0, sizeof(cp));
195         cp.argv = argv;
196         cp.out = -1;
197         cp.git_cmd = 1;
198
199         if (start_command(&cp))
200                 die("could not run stash.");
201         len = strbuf_read(&buffer, cp.out, 1024);
202         close(cp.out);
203
204         if (finish_command(&cp) || len < 0)
205                 die("stash failed");
206         else if (!len)
207                 return;
208         strbuf_setlen(&buffer, buffer.len-1);
209         if (get_sha1(buffer.buf, stash))
210                 die("not a valid object: %s", buffer.buf);
211 }
212
213 static void reset_hard(unsigned const char *sha1, int verbose)
214 {
215         int i = 0;
216         const char *args[6];
217
218         args[i++] = "read-tree";
219         if (verbose)
220                 args[i++] = "-v";
221         args[i++] = "--reset";
222         args[i++] = "-u";
223         args[i++] = sha1_to_hex(sha1);
224         args[i] = NULL;
225
226         if (run_command_v_opt(args, RUN_GIT_CMD))
227                 die("read-tree failed");
228 }
229
230 static void restore_state(void)
231 {
232         struct strbuf sb = STRBUF_INIT;
233         const char *args[] = { "stash", "apply", NULL, NULL };
234
235         if (is_null_sha1(stash))
236                 return;
237
238         reset_hard(head, 1);
239
240         args[2] = sha1_to_hex(stash);
241
242         /*
243          * It is OK to ignore error here, for example when there was
244          * nothing to restore.
245          */
246         run_command_v_opt(args, RUN_GIT_CMD);
247
248         strbuf_release(&sb);
249         refresh_cache(REFRESH_QUIET);
250 }
251
252 /* This is called when no merge was necessary. */
253 static void finish_up_to_date(const char *msg)
254 {
255         if (verbosity >= 0)
256                 printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
257         drop_save();
258 }
259
260 static void squash_message(void)
261 {
262         struct rev_info rev;
263         struct commit *commit;
264         struct strbuf out = STRBUF_INIT;
265         struct commit_list *j;
266         int fd;
267
268         printf("Squash commit -- not updating HEAD\n");
269         fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
270         if (fd < 0)
271                 die("Could not write to %s", git_path("SQUASH_MSG"));
272
273         init_revisions(&rev, NULL);
274         rev.ignore_merges = 1;
275         rev.commit_format = CMIT_FMT_MEDIUM;
276
277         commit = lookup_commit(head);
278         commit->object.flags |= UNINTERESTING;
279         add_pending_object(&rev, &commit->object, NULL);
280
281         for (j = remoteheads; j; j = j->next)
282                 add_pending_object(&rev, &j->item->object, NULL);
283
284         setup_revisions(0, NULL, &rev, NULL);
285         if (prepare_revision_walk(&rev))
286                 die("revision walk setup failed");
287
288         strbuf_addstr(&out, "Squashed commit of the following:\n");
289         while ((commit = get_revision(&rev)) != NULL) {
290                 strbuf_addch(&out, '\n');
291                 strbuf_addf(&out, "commit %s\n",
292                         sha1_to_hex(commit->object.sha1));
293                 pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
294                         NULL, NULL, rev.date_mode, 0);
295         }
296         write(fd, out.buf, out.len);
297         close(fd);
298         strbuf_release(&out);
299 }
300
301 static int run_hook(const char *name)
302 {
303         struct child_process hook;
304         const char *argv[3], *env[2];
305         char index[PATH_MAX];
306
307         argv[0] = git_path("hooks/%s", name);
308         if (access(argv[0], X_OK) < 0)
309                 return 0;
310
311         snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
312         env[0] = index;
313         env[1] = NULL;
314
315         if (squash)
316                 argv[1] = "1";
317         else
318                 argv[1] = "0";
319         argv[2] = NULL;
320
321         memset(&hook, 0, sizeof(hook));
322         hook.argv = argv;
323         hook.no_stdin = 1;
324         hook.stdout_to_stderr = 1;
325         hook.env = env;
326
327         return run_command(&hook);
328 }
329
330 static void finish(const unsigned char *new_head, const char *msg)
331 {
332         struct strbuf reflog_message = STRBUF_INIT;
333
334         if (!msg)
335                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
336         else {
337                 if (verbosity >= 0)
338                         printf("%s\n", msg);
339                 strbuf_addf(&reflog_message, "%s: %s",
340                         getenv("GIT_REFLOG_ACTION"), msg);
341         }
342         if (squash) {
343                 squash_message();
344         } else {
345                 if (verbosity >= 0 && !merge_msg.len)
346                         printf("No merge message -- not updating HEAD\n");
347                 else {
348                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
349                         update_ref(reflog_message.buf, "HEAD",
350                                 new_head, head, 0,
351                                 DIE_ON_ERR);
352                         /*
353                          * We ignore errors in 'gc --auto', since the
354                          * user should see them.
355                          */
356                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
357                 }
358         }
359         if (new_head && show_diffstat) {
360                 struct diff_options opts;
361                 diff_setup(&opts);
362                 opts.output_format |=
363                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
364                 opts.detect_rename = DIFF_DETECT_RENAME;
365                 if (diff_use_color_default > 0)
366                         DIFF_OPT_SET(&opts, COLOR_DIFF);
367                 if (diff_setup_done(&opts) < 0)
368                         die("diff_setup_done failed");
369                 diff_tree_sha1(head, new_head, "", &opts);
370                 diffcore_std(&opts);
371                 diff_flush(&opts);
372         }
373
374         /* Run a post-merge hook */
375         run_hook("post-merge");
376
377         strbuf_release(&reflog_message);
378 }
379
380 /* Get the name for the merge commit's message. */
381 static void merge_name(const char *remote, struct strbuf *msg)
382 {
383         struct object *remote_head;
384         unsigned char branch_head[20], buf_sha[20];
385         struct strbuf buf = STRBUF_INIT;
386         const char *ptr;
387         int len, early;
388
389         memset(branch_head, 0, sizeof(branch_head));
390         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
391         if (!remote_head)
392                 die("'%s' does not point to a commit", remote);
393
394         strbuf_addstr(&buf, "refs/heads/");
395         strbuf_addstr(&buf, remote);
396         resolve_ref(buf.buf, branch_head, 0, 0);
397
398         if (!hashcmp(remote_head->sha1, branch_head)) {
399                 strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
400                         sha1_to_hex(branch_head), remote);
401                 return;
402         }
403
404         /* See if remote matches <name>^^^.. or <name>~<number> */
405         for (len = 0, ptr = remote + strlen(remote);
406              remote < ptr && ptr[-1] == '^';
407              ptr--)
408                 len++;
409         if (len)
410                 early = 1;
411         else {
412                 early = 0;
413                 ptr = strrchr(remote, '~');
414                 if (ptr) {
415                         int seen_nonzero = 0;
416
417                         len++; /* count ~ */
418                         while (*++ptr && isdigit(*ptr)) {
419                                 seen_nonzero |= (*ptr != '0');
420                                 len++;
421                         }
422                         if (*ptr)
423                                 len = 0; /* not ...~<number> */
424                         else if (seen_nonzero)
425                                 early = 1;
426                         else if (len == 1)
427                                 early = 1; /* "name~" is "name~1"! */
428                 }
429         }
430         if (len) {
431                 struct strbuf truname = STRBUF_INIT;
432                 strbuf_addstr(&truname, "refs/heads/");
433                 strbuf_addstr(&truname, remote);
434                 strbuf_setlen(&truname, truname.len - len);
435                 if (resolve_ref(truname.buf, buf_sha, 0, 0)) {
436                         strbuf_addf(msg,
437                                     "%s\t\tbranch '%s'%s of .\n",
438                                     sha1_to_hex(remote_head->sha1),
439                                     truname.buf + 11,
440                                     (early ? " (early part)" : ""));
441                         return;
442                 }
443         }
444
445         if (!strcmp(remote, "FETCH_HEAD") &&
446                         !access(git_path("FETCH_HEAD"), R_OK)) {
447                 FILE *fp;
448                 struct strbuf line = STRBUF_INIT;
449                 char *ptr;
450
451                 fp = fopen(git_path("FETCH_HEAD"), "r");
452                 if (!fp)
453                         die("could not open %s for reading: %s",
454                                 git_path("FETCH_HEAD"), strerror(errno));
455                 strbuf_getline(&line, fp, '\n');
456                 fclose(fp);
457                 ptr = strstr(line.buf, "\tnot-for-merge\t");
458                 if (ptr)
459                         strbuf_remove(&line, ptr-line.buf+1, 13);
460                 strbuf_addbuf(msg, &line);
461                 strbuf_release(&line);
462                 return;
463         }
464         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
465                 sha1_to_hex(remote_head->sha1), remote);
466 }
467
468 static int git_merge_config(const char *k, const char *v, void *cb)
469 {
470         if (branch && !prefixcmp(k, "branch.") &&
471                 !prefixcmp(k + 7, branch) &&
472                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
473                 const char **argv;
474                 int argc;
475                 char *buf;
476
477                 buf = xstrdup(v);
478                 argc = split_cmdline(buf, &argv);
479                 if (argc < 0)
480                         die("Bad branch.%s.mergeoptions string", branch);
481                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
482                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
483                 argc++;
484                 parse_options(argc, argv, builtin_merge_options,
485                               builtin_merge_usage, 0);
486                 free(buf);
487         }
488
489         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
490                 show_diffstat = git_config_bool(k, v);
491         else if (!strcmp(k, "pull.twohead"))
492                 return git_config_string(&pull_twohead, k, v);
493         else if (!strcmp(k, "pull.octopus"))
494                 return git_config_string(&pull_octopus, k, v);
495         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
496                 option_log = git_config_bool(k, v);
497         return git_diff_ui_config(k, v, cb);
498 }
499
500 static int read_tree_trivial(unsigned char *common, unsigned char *head,
501                              unsigned char *one)
502 {
503         int i, nr_trees = 0;
504         struct tree *trees[MAX_UNPACK_TREES];
505         struct tree_desc t[MAX_UNPACK_TREES];
506         struct unpack_trees_options opts;
507
508         memset(&opts, 0, sizeof(opts));
509         opts.head_idx = 2;
510         opts.src_index = &the_index;
511         opts.dst_index = &the_index;
512         opts.update = 1;
513         opts.verbose_update = 1;
514         opts.trivial_merges_only = 1;
515         opts.merge = 1;
516         trees[nr_trees] = parse_tree_indirect(common);
517         if (!trees[nr_trees++])
518                 return -1;
519         trees[nr_trees] = parse_tree_indirect(head);
520         if (!trees[nr_trees++])
521                 return -1;
522         trees[nr_trees] = parse_tree_indirect(one);
523         if (!trees[nr_trees++])
524                 return -1;
525         opts.fn = threeway_merge;
526         cache_tree_free(&active_cache_tree);
527         for (i = 0; i < nr_trees; i++) {
528                 parse_tree(trees[i]);
529                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
530         }
531         if (unpack_trees(nr_trees, t, &opts))
532                 return -1;
533         return 0;
534 }
535
536 static void write_tree_trivial(unsigned char *sha1)
537 {
538         if (write_cache_as_tree(sha1, 0, NULL))
539                 die("git write-tree failed to write a tree");
540 }
541
542 static int try_merge_strategy(const char *strategy, struct commit_list *common,
543                               const char *head_arg)
544 {
545         const char **args;
546         int i = 0, ret;
547         struct commit_list *j;
548         struct strbuf buf = STRBUF_INIT;
549         int index_fd;
550         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
551
552         index_fd = hold_locked_index(lock, 1);
553         refresh_cache(REFRESH_QUIET);
554         if (active_cache_changed &&
555                         (write_cache(index_fd, active_cache, active_nr) ||
556                          commit_locked_index(lock)))
557                 return error("Unable to write index.");
558         rollback_lock_file(lock);
559
560         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
561                 int clean;
562                 struct commit *result;
563                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
564                 int index_fd;
565                 struct commit_list *reversed = NULL;
566                 struct merge_options o;
567
568                 if (remoteheads->next) {
569                         error("Not handling anything other than two heads merge.");
570                         return 2;
571                 }
572
573                 init_merge_options(&o);
574                 if (!strcmp(strategy, "subtree"))
575                         o.subtree_merge = 1;
576
577                 o.branch1 = head_arg;
578                 o.branch2 = remoteheads->item->util;
579
580                 for (j = common; j; j = j->next)
581                         commit_list_insert(j->item, &reversed);
582
583                 index_fd = hold_locked_index(lock, 1);
584                 clean = merge_recursive(&o, lookup_commit(head),
585                                 remoteheads->item, reversed, &result);
586                 if (active_cache_changed &&
587                                 (write_cache(index_fd, active_cache, active_nr) ||
588                                  commit_locked_index(lock)))
589                         die ("unable to write %s", get_index_file());
590                 rollback_lock_file(lock);
591                 return clean ? 0 : 1;
592         } else {
593                 args = xmalloc((4 + commit_list_count(common) +
594                                         commit_list_count(remoteheads)) * sizeof(char *));
595                 strbuf_addf(&buf, "merge-%s", strategy);
596                 args[i++] = buf.buf;
597                 for (j = common; j; j = j->next)
598                         args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
599                 args[i++] = "--";
600                 args[i++] = head_arg;
601                 for (j = remoteheads; j; j = j->next)
602                         args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
603                 args[i] = NULL;
604                 ret = run_command_v_opt(args, RUN_GIT_CMD);
605                 strbuf_release(&buf);
606                 i = 1;
607                 for (j = common; j; j = j->next)
608                         free((void *)args[i++]);
609                 i += 2;
610                 for (j = remoteheads; j; j = j->next)
611                         free((void *)args[i++]);
612                 free(args);
613                 discard_cache();
614                 if (read_cache() < 0)
615                         die("failed to read the cache");
616                 return -ret;
617         }
618 }
619
620 static void count_diff_files(struct diff_queue_struct *q,
621                              struct diff_options *opt, void *data)
622 {
623         int *count = data;
624
625         (*count) += q->nr;
626 }
627
628 static int count_unmerged_entries(void)
629 {
630         const struct index_state *state = &the_index;
631         int i, ret = 0;
632
633         for (i = 0; i < state->cache_nr; i++)
634                 if (ce_stage(state->cache[i]))
635                         ret++;
636
637         return ret;
638 }
639
640 static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
641 {
642         struct tree *trees[MAX_UNPACK_TREES];
643         struct unpack_trees_options opts;
644         struct tree_desc t[MAX_UNPACK_TREES];
645         int i, fd, nr_trees = 0;
646         struct dir_struct dir;
647         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
648
649         refresh_cache(REFRESH_QUIET);
650
651         fd = hold_locked_index(lock_file, 1);
652
653         memset(&trees, 0, sizeof(trees));
654         memset(&opts, 0, sizeof(opts));
655         memset(&t, 0, sizeof(t));
656         memset(&dir, 0, sizeof(dir));
657         dir.show_ignored = 1;
658         dir.exclude_per_dir = ".gitignore";
659         opts.dir = &dir;
660
661         opts.head_idx = 1;
662         opts.src_index = &the_index;
663         opts.dst_index = &the_index;
664         opts.update = 1;
665         opts.verbose_update = 1;
666         opts.merge = 1;
667         opts.fn = twoway_merge;
668
669         trees[nr_trees] = parse_tree_indirect(head);
670         if (!trees[nr_trees++])
671                 return -1;
672         trees[nr_trees] = parse_tree_indirect(remote);
673         if (!trees[nr_trees++])
674                 return -1;
675         for (i = 0; i < nr_trees; i++) {
676                 parse_tree(trees[i]);
677                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
678         }
679         if (unpack_trees(nr_trees, t, &opts))
680                 return -1;
681         if (write_cache(fd, active_cache, active_nr) ||
682                 commit_locked_index(lock_file))
683                 die("unable to write new index file");
684         return 0;
685 }
686
687 static void split_merge_strategies(const char *string, struct strategy **list,
688                                    int *nr, int *alloc)
689 {
690         char *p, *q, *buf;
691
692         if (!string)
693                 return;
694
695         buf = xstrdup(string);
696         q = buf;
697         for (;;) {
698                 p = strchr(q, ' ');
699                 if (!p) {
700                         ALLOC_GROW(*list, *nr + 1, *alloc);
701                         (*list)[(*nr)++].name = xstrdup(q);
702                         free(buf);
703                         return;
704                 } else {
705                         *p = '\0';
706                         ALLOC_GROW(*list, *nr + 1, *alloc);
707                         (*list)[(*nr)++].name = xstrdup(q);
708                         q = ++p;
709                 }
710         }
711 }
712
713 static void add_strategies(const char *string, unsigned attr)
714 {
715         struct strategy *list = NULL;
716         int list_alloc = 0, list_nr = 0, i;
717
718         memset(&list, 0, sizeof(list));
719         split_merge_strategies(string, &list, &list_nr, &list_alloc);
720         if (list) {
721                 for (i = 0; i < list_nr; i++)
722                         append_strategy(get_strategy(list[i].name));
723                 return;
724         }
725         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
726                 if (all_strategy[i].attr & attr)
727                         append_strategy(&all_strategy[i]);
728
729 }
730
731 static int merge_trivial(void)
732 {
733         unsigned char result_tree[20], result_commit[20];
734         struct commit_list *parent = xmalloc(sizeof(*parent));
735
736         write_tree_trivial(result_tree);
737         printf("Wonderful.\n");
738         parent->item = lookup_commit(head);
739         parent->next = xmalloc(sizeof(*parent->next));
740         parent->next->item = remoteheads->item;
741         parent->next->next = NULL;
742         commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
743         finish(result_commit, "In-index merge");
744         drop_save();
745         return 0;
746 }
747
748 static int finish_automerge(struct commit_list *common,
749                             unsigned char *result_tree,
750                             const char *wt_strategy)
751 {
752         struct commit_list *parents = NULL, *j;
753         struct strbuf buf = STRBUF_INIT;
754         unsigned char result_commit[20];
755
756         free_commit_list(common);
757         if (allow_fast_forward) {
758                 parents = remoteheads;
759                 commit_list_insert(lookup_commit(head), &parents);
760                 parents = reduce_heads(parents);
761         } else {
762                 struct commit_list **pptr = &parents;
763
764                 pptr = &commit_list_insert(lookup_commit(head),
765                                 pptr)->next;
766                 for (j = remoteheads; j; j = j->next)
767                         pptr = &commit_list_insert(j->item, pptr)->next;
768         }
769         free_commit_list(remoteheads);
770         strbuf_addch(&merge_msg, '\n');
771         commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
772         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
773         finish(result_commit, buf.buf);
774         strbuf_release(&buf);
775         drop_save();
776         return 0;
777 }
778
779 static int suggest_conflicts(void)
780 {
781         FILE *fp;
782         int pos;
783
784         fp = fopen(git_path("MERGE_MSG"), "a");
785         if (!fp)
786                 die("Could open %s for writing", git_path("MERGE_MSG"));
787         fprintf(fp, "\nConflicts:\n");
788         for (pos = 0; pos < active_nr; pos++) {
789                 struct cache_entry *ce = active_cache[pos];
790
791                 if (ce_stage(ce)) {
792                         fprintf(fp, "\t%s\n", ce->name);
793                         while (pos + 1 < active_nr &&
794                                         !strcmp(ce->name,
795                                                 active_cache[pos + 1]->name))
796                                 pos++;
797                 }
798         }
799         fclose(fp);
800         rerere();
801         printf("Automatic merge failed; "
802                         "fix conflicts and then commit the result.\n");
803         return 1;
804 }
805
806 static struct commit *is_old_style_invocation(int argc, const char **argv)
807 {
808         struct commit *second_token = NULL;
809         if (argc > 1) {
810                 unsigned char second_sha1[20];
811
812                 if (get_sha1(argv[1], second_sha1))
813                         return NULL;
814                 second_token = lookup_commit_reference_gently(second_sha1, 0);
815                 if (!second_token)
816                         die("'%s' is not a commit", argv[1]);
817                 if (hashcmp(second_token->object.sha1, head))
818                         return NULL;
819         }
820         return second_token;
821 }
822
823 static int evaluate_result(void)
824 {
825         int cnt = 0;
826         struct rev_info rev;
827
828         /* Check how many files differ. */
829         init_revisions(&rev, "");
830         setup_revisions(0, NULL, &rev, NULL);
831         rev.diffopt.output_format |=
832                 DIFF_FORMAT_CALLBACK;
833         rev.diffopt.format_callback = count_diff_files;
834         rev.diffopt.format_callback_data = &cnt;
835         run_diff_files(&rev, 0);
836
837         /*
838          * Check how many unmerged entries are
839          * there.
840          */
841         cnt += count_unmerged_entries();
842
843         return cnt;
844 }
845
846 int cmd_merge(int argc, const char **argv, const char *prefix)
847 {
848         unsigned char result_tree[20];
849         struct strbuf buf = STRBUF_INIT;
850         const char *head_arg;
851         int flag, head_invalid = 0, i;
852         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
853         struct commit_list *common = NULL;
854         const char *best_strategy = NULL, *wt_strategy = NULL;
855         struct commit_list **remotes = &remoteheads;
856
857         setup_work_tree();
858         if (read_cache_unmerged())
859                 die("You are in the middle of a conflicted merge.");
860
861         /*
862          * Check if we are _not_ on a detached HEAD, i.e. if there is a
863          * current branch.
864          */
865         branch = resolve_ref("HEAD", head, 0, &flag);
866         if (branch && !prefixcmp(branch, "refs/heads/"))
867                 branch += 11;
868         if (is_null_sha1(head))
869                 head_invalid = 1;
870
871         git_config(git_merge_config, NULL);
872
873         /* for color.ui */
874         if (diff_use_color_default == -1)
875                 diff_use_color_default = git_use_color_default;
876
877         argc = parse_options(argc, argv, builtin_merge_options,
878                         builtin_merge_usage, 0);
879         if (verbosity < 0)
880                 show_diffstat = 0;
881
882         if (squash) {
883                 if (!allow_fast_forward)
884                         die("You cannot combine --squash with --no-ff.");
885                 option_commit = 0;
886         }
887
888         if (!argc)
889                 usage_with_options(builtin_merge_usage,
890                         builtin_merge_options);
891
892         /*
893          * This could be traditional "merge <msg> HEAD <commit>..."  and
894          * the way we can tell it is to see if the second token is HEAD,
895          * but some people might have misused the interface and used a
896          * committish that is the same as HEAD there instead.
897          * Traditional format never would have "-m" so it is an
898          * additional safety measure to check for it.
899          */
900
901         if (!have_message && is_old_style_invocation(argc, argv)) {
902                 strbuf_addstr(&merge_msg, argv[0]);
903                 head_arg = argv[1];
904                 argv += 2;
905                 argc -= 2;
906         } else if (head_invalid) {
907                 struct object *remote_head;
908                 /*
909                  * If the merged head is a valid one there is no reason
910                  * to forbid "git merge" into a branch yet to be born.
911                  * We do the same for "git pull".
912                  */
913                 if (argc != 1)
914                         die("Can merge only exactly one commit into "
915                                 "empty head");
916                 if (squash)
917                         die("Squash commit into empty head not supported yet");
918                 if (!allow_fast_forward)
919                         die("Non-fast-forward commit does not make sense into "
920                             "an empty head");
921                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
922                 if (!remote_head)
923                         die("%s - not something we can merge", argv[0]);
924                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
925                                 DIE_ON_ERR);
926                 reset_hard(remote_head->sha1, 0);
927                 return 0;
928         } else {
929                 struct strbuf msg = STRBUF_INIT;
930
931                 /* We are invoked directly as the first-class UI. */
932                 head_arg = "HEAD";
933
934                 /*
935                  * All the rest are the commits being merged;
936                  * prepare the standard merge summary message to
937                  * be appended to the given message.  If remote
938                  * is invalid we will die later in the common
939                  * codepath so we discard the error in this
940                  * loop.
941                  */
942                 for (i = 0; i < argc; i++)
943                         merge_name(argv[i], &msg);
944                 fmt_merge_msg(option_log, &msg, &merge_msg);
945                 if (merge_msg.len)
946                         strbuf_setlen(&merge_msg, merge_msg.len-1);
947         }
948
949         if (head_invalid || !argc)
950                 usage_with_options(builtin_merge_usage,
951                         builtin_merge_options);
952
953         strbuf_addstr(&buf, "merge");
954         for (i = 0; i < argc; i++)
955                 strbuf_addf(&buf, " %s", argv[i]);
956         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
957         strbuf_reset(&buf);
958
959         for (i = 0; i < argc; i++) {
960                 struct object *o;
961                 struct commit *commit;
962
963                 o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
964                 if (!o)
965                         die("%s - not something we can merge", argv[i]);
966                 commit = lookup_commit(o->sha1);
967                 commit->util = (void *)argv[i];
968                 remotes = &commit_list_insert(commit, remotes)->next;
969
970                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
971                 setenv(buf.buf, argv[i], 1);
972                 strbuf_reset(&buf);
973         }
974
975         if (!use_strategies) {
976                 if (!remoteheads->next)
977                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
978                 else
979                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
980         }
981
982         for (i = 0; i < use_strategies_nr; i++) {
983                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
984                         allow_fast_forward = 0;
985                 if (use_strategies[i]->attr & NO_TRIVIAL)
986                         allow_trivial = 0;
987         }
988
989         if (!remoteheads->next)
990                 common = get_merge_bases(lookup_commit(head),
991                                 remoteheads->item, 1);
992         else {
993                 struct commit_list *list = remoteheads;
994                 commit_list_insert(lookup_commit(head), &list);
995                 common = get_octopus_merge_bases(list);
996                 free(list);
997         }
998
999         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
1000                 DIE_ON_ERR);
1001
1002         if (!common)
1003                 ; /* No common ancestors found. We need a real merge. */
1004         else if (!remoteheads->next && !common->next &&
1005                         common->item == remoteheads->item) {
1006                 /*
1007                  * If head can reach all the merge then we are up to date.
1008                  * but first the most common case of merging one remote.
1009                  */
1010                 finish_up_to_date("Already up-to-date.");
1011                 return 0;
1012         } else if (allow_fast_forward && !remoteheads->next &&
1013                         !common->next &&
1014                         !hashcmp(common->item->object.sha1, head)) {
1015                 /* Again the most common case of merging one remote. */
1016                 struct strbuf msg = STRBUF_INIT;
1017                 struct object *o;
1018                 char hex[41];
1019
1020                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
1021
1022                 if (verbosity >= 0)
1023                         printf("Updating %s..%s\n",
1024                                 hex,
1025                                 find_unique_abbrev(remoteheads->item->object.sha1,
1026                                 DEFAULT_ABBREV));
1027                 strbuf_addstr(&msg, "Fast forward");
1028                 if (have_message)
1029                         strbuf_addstr(&msg,
1030                                 " (no commit created; -m option ignored)");
1031                 o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
1032                         0, NULL, OBJ_COMMIT);
1033                 if (!o)
1034                         return 1;
1035
1036                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
1037                         return 1;
1038
1039                 finish(o->sha1, msg.buf);
1040                 drop_save();
1041                 return 0;
1042         } else if (!remoteheads->next && common->next)
1043                 ;
1044                 /*
1045                  * We are not doing octopus and not fast forward.  Need
1046                  * a real merge.
1047                  */
1048         else if (!remoteheads->next && !common->next && option_commit) {
1049                 /*
1050                  * We are not doing octopus, not fast forward, and have
1051                  * only one common.
1052                  */
1053                 refresh_cache(REFRESH_QUIET);
1054                 if (allow_trivial) {
1055                         /* See if it is really trivial. */
1056                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1057                         printf("Trying really trivial in-index merge...\n");
1058                         if (!read_tree_trivial(common->item->object.sha1,
1059                                         head, remoteheads->item->object.sha1))
1060                                 return merge_trivial();
1061                         printf("Nope.\n");
1062                 }
1063         } else {
1064                 /*
1065                  * An octopus.  If we can reach all the remote we are up
1066                  * to date.
1067                  */
1068                 int up_to_date = 1;
1069                 struct commit_list *j;
1070
1071                 for (j = remoteheads; j; j = j->next) {
1072                         struct commit_list *common_one;
1073
1074                         /*
1075                          * Here we *have* to calculate the individual
1076                          * merge_bases again, otherwise "git merge HEAD^
1077                          * HEAD^^" would be missed.
1078                          */
1079                         common_one = get_merge_bases(lookup_commit(head),
1080                                 j->item, 1);
1081                         if (hashcmp(common_one->item->object.sha1,
1082                                 j->item->object.sha1)) {
1083                                 up_to_date = 0;
1084                                 break;
1085                         }
1086                 }
1087                 if (up_to_date) {
1088                         finish_up_to_date("Already up-to-date. Yeeah!");
1089                         return 0;
1090                 }
1091         }
1092
1093         /* We are going to make a new commit. */
1094         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1095
1096         /*
1097          * At this point, we need a real merge.  No matter what strategy
1098          * we use, it would operate on the index, possibly affecting the
1099          * working tree, and when resolved cleanly, have the desired
1100          * tree in the index -- this means that the index must be in
1101          * sync with the head commit.  The strategies are responsible
1102          * to ensure this.
1103          */
1104         if (use_strategies_nr != 1) {
1105                 /*
1106                  * Stash away the local changes so that we can try more
1107                  * than one.
1108                  */
1109                 save_state();
1110         } else {
1111                 memcpy(stash, null_sha1, 20);
1112         }
1113
1114         for (i = 0; i < use_strategies_nr; i++) {
1115                 int ret;
1116                 if (i) {
1117                         printf("Rewinding the tree to pristine...\n");
1118                         restore_state();
1119                 }
1120                 if (use_strategies_nr != 1)
1121                         printf("Trying merge strategy %s...\n",
1122                                 use_strategies[i]->name);
1123                 /*
1124                  * Remember which strategy left the state in the working
1125                  * tree.
1126                  */
1127                 wt_strategy = use_strategies[i]->name;
1128
1129                 ret = try_merge_strategy(use_strategies[i]->name,
1130                         common, head_arg);
1131                 if (!option_commit && !ret) {
1132                         merge_was_ok = 1;
1133                         /*
1134                          * This is necessary here just to avoid writing
1135                          * the tree, but later we will *not* exit with
1136                          * status code 1 because merge_was_ok is set.
1137                          */
1138                         ret = 1;
1139                 }
1140
1141                 if (ret) {
1142                         /*
1143                          * The backend exits with 1 when conflicts are
1144                          * left to be resolved, with 2 when it does not
1145                          * handle the given merge at all.
1146                          */
1147                         if (ret == 1) {
1148                                 int cnt = evaluate_result();
1149
1150                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1151                                         best_strategy = use_strategies[i]->name;
1152                                         best_cnt = cnt;
1153                                 }
1154                         }
1155                         if (merge_was_ok)
1156                                 break;
1157                         else
1158                                 continue;
1159                 }
1160
1161                 /* Automerge succeeded. */
1162                 write_tree_trivial(result_tree);
1163                 automerge_was_ok = 1;
1164                 break;
1165         }
1166
1167         /*
1168          * If we have a resulting tree, that means the strategy module
1169          * auto resolved the merge cleanly.
1170          */
1171         if (automerge_was_ok)
1172                 return finish_automerge(common, result_tree, wt_strategy);
1173
1174         /*
1175          * Pick the result from the best strategy and have the user fix
1176          * it up.
1177          */
1178         if (!best_strategy) {
1179                 restore_state();
1180                 if (use_strategies_nr > 1)
1181                         fprintf(stderr,
1182                                 "No merge strategy handled the merge.\n");
1183                 else
1184                         fprintf(stderr, "Merge with strategy %s failed.\n",
1185                                 use_strategies[0]->name);
1186                 return 2;
1187         } else if (best_strategy == wt_strategy)
1188                 ; /* We already have its result in the working tree. */
1189         else {
1190                 printf("Rewinding the tree to pristine...\n");
1191                 restore_state();
1192                 printf("Using the %s to prepare resolving by hand.\n",
1193                         best_strategy);
1194                 try_merge_strategy(best_strategy, common, head_arg);
1195         }
1196
1197         if (squash)
1198                 finish(NULL, NULL);
1199         else {
1200                 int fd;
1201                 struct commit_list *j;
1202
1203                 for (j = remoteheads; j; j = j->next)
1204                         strbuf_addf(&buf, "%s\n",
1205                                 sha1_to_hex(j->item->object.sha1));
1206                 fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1207                 if (fd < 0)
1208                         die("Could open %s for writing",
1209                                 git_path("MERGE_HEAD"));
1210                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1211                         die("Could not write to %s", git_path("MERGE_HEAD"));
1212                 close(fd);
1213                 strbuf_addch(&merge_msg, '\n');
1214                 fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
1215                 if (fd < 0)
1216                         die("Could open %s for writing", git_path("MERGE_MSG"));
1217                 if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1218                         merge_msg.len)
1219                         die("Could not write to %s", git_path("MERGE_MSG"));
1220                 close(fd);
1221                 fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
1222                 if (fd < 0)
1223                         die("Could open %s for writing", git_path("MERGE_MODE"));
1224                 strbuf_reset(&buf);
1225                 if (!allow_fast_forward)
1226                         strbuf_addf(&buf, "no-ff");
1227                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1228                         die("Could not write to %s", git_path("MERGE_MODE"));
1229                 close(fd);
1230         }
1231
1232         if (merge_was_ok) {
1233                 fprintf(stderr, "Automatic merge went well; "
1234                         "stopped before committing as requested\n");
1235                 return 0;
1236         } else
1237                 return suggest_conflicts();
1238 }