Remove a left-over file from t/t5100
[git/dscho.git] / builtin-merge.c
blobb6b84286b26a4317dfd5185ae83fd861c6f9fa7d
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  */
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"
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)
33 struct strategy {
34         const char *name;
35         unsigned attr;
38 static const char * const builtin_merge_usage[] = {
39         "git merge [options] <remote>...",
40         "git merge [options] <msg> HEAD <remote>",
41         NULL
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;
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 },
63 static const char *pull_twohead, *pull_octopus;
65 static int option_parse_message(const struct option *opt,
66                                 const char *arg, int unset)
68         struct strbuf *buf = opt->value;
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;
80 static struct strategy *get_strategy(const char *name)
82         int i;
83         struct strategy *ret;
84         static struct cmdnames main_cmds, other_cmds;
85         static int loaded;
87         if (!name)
88                 return NULL;
90         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
91                 if (!strcmp(name, all_strategy[i].name))
92                         return &all_strategy[i];
94         if (!loaded) {
95                 struct cmdnames not_strategies;
96                 loaded = 1;
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         }
127         ret = xcalloc(1, sizeof(struct strategy));
128         ret->name = xstrdup(name);
129         return ret;
132 static void append_strategy(struct strategy *s)
134         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
135         use_strategies[use_strategies_nr++] = s;
138 static int option_parse_strategy(const struct option *opt,
139                                  const char *name, int unset)
141         if (unset)
142                 return 0;
144         append_strategy(get_strategy(name));
145         return 0;
148 static int option_parse_n(const struct option *opt,
149                           const char *arg, int unset)
151         show_diffstat = unset;
152         return 0;
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()
179 /* Cleans up metadata that is uninteresting after a succeeded merge. */
180 static void drop_save(void)
182         unlink(git_path("MERGE_HEAD"));
183         unlink(git_path("MERGE_MSG"));
184         unlink(git_path("MERGE_MODE"));
187 static void save_state(void)
189         int len;
190         struct child_process cp;
191         struct strbuf buffer = STRBUF_INIT;
192         const char *argv[] = {"stash", "create", NULL};
194         memset(&cp, 0, sizeof(cp));
195         cp.argv = argv;
196         cp.out = -1;
197         cp.git_cmd = 1;
199         if (start_command(&cp))
200                 die("could not run stash.");
201         len = strbuf_read(&buffer, cp.out, 1024);
202         close(cp.out);
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);
213 static void reset_hard(unsigned const char *sha1, int verbose)
215         int i = 0;
216         const char *args[6];
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;
226         if (run_command_v_opt(args, RUN_GIT_CMD))
227                 die("read-tree failed");
230 static void restore_state(void)
232         struct strbuf sb = STRBUF_INIT;
233         const char *args[] = { "stash", "apply", NULL, NULL };
235         if (is_null_sha1(stash))
236                 return;
238         reset_hard(head, 1);
240         args[2] = sha1_to_hex(stash);
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);
248         strbuf_release(&sb);
249         refresh_cache(REFRESH_QUIET);
252 /* This is called when no merge was necessary. */
253 static void finish_up_to_date(const char *msg)
255         if (verbosity >= 0)
256                 printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
257         drop_save();
260 static void squash_message(void)
262         struct rev_info rev;
263         struct commit *commit;
264         struct strbuf out = STRBUF_INIT;
265         struct commit_list *j;
266         int fd;
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_errno("Could not write to '%s'", git_path("SQUASH_MSG"));
273         init_revisions(&rev, NULL);
274         rev.ignore_merges = 1;
275         rev.commit_format = CMIT_FMT_MEDIUM;
277         commit = lookup_commit(head);
278         commit->object.flags |= UNINTERESTING;
279         add_pending_object(&rev, &commit->object, NULL);
281         for (j = remoteheads; j; j = j->next)
282                 add_pending_object(&rev, &j->item->object, NULL);
284         setup_revisions(0, NULL, &rev, NULL);
285         if (prepare_revision_walk(&rev))
286                 die("revision walk setup failed");
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         if (write(fd, out.buf, out.len) < 0)
297                 die_errno("Writing SQUASH_MSG");
298         if (close(fd))
299                 die_errno("Finishing SQUASH_MSG");
300         strbuf_release(&out);
303 static void finish(const unsigned char *new_head, const char *msg)
305         struct strbuf reflog_message = STRBUF_INIT;
307         if (!msg)
308                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
309         else {
310                 if (verbosity >= 0)
311                         printf("%s\n", msg);
312                 strbuf_addf(&reflog_message, "%s: %s",
313                         getenv("GIT_REFLOG_ACTION"), msg);
314         }
315         if (squash) {
316                 squash_message();
317         } else {
318                 if (verbosity >= 0 && !merge_msg.len)
319                         printf("No merge message -- not updating HEAD\n");
320                 else {
321                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
322                         update_ref(reflog_message.buf, "HEAD",
323                                 new_head, head, 0,
324                                 DIE_ON_ERR);
325                         /*
326                          * We ignore errors in 'gc --auto', since the
327                          * user should see them.
328                          */
329                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
330                 }
331         }
332         if (new_head && show_diffstat) {
333                 struct diff_options opts;
334                 diff_setup(&opts);
335                 opts.output_format |=
336                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
337                 opts.detect_rename = DIFF_DETECT_RENAME;
338                 if (diff_use_color_default > 0)
339                         DIFF_OPT_SET(&opts, COLOR_DIFF);
340                 if (diff_setup_done(&opts) < 0)
341                         die("diff_setup_done failed");
342                 diff_tree_sha1(head, new_head, "", &opts);
343                 diffcore_std(&opts);
344                 diff_flush(&opts);
345         }
347         /* Run a post-merge hook */
348         run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
350         strbuf_release(&reflog_message);
353 /* Get the name for the merge commit's message. */
354 static void merge_name(const char *remote, struct strbuf *msg)
356         struct object *remote_head;
357         unsigned char branch_head[20], buf_sha[20];
358         struct strbuf buf = STRBUF_INIT;
359         struct strbuf bname = STRBUF_INIT;
360         const char *ptr;
361         char *found_ref;
362         int len, early;
364         strbuf_branchname(&bname, remote);
365         remote = bname.buf;
367         memset(branch_head, 0, sizeof(branch_head));
368         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
369         if (!remote_head)
370                 die("'%s' does not point to a commit", remote);
372         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
373                 if (!prefixcmp(found_ref, "refs/heads/")) {
374                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
375                                     sha1_to_hex(branch_head), remote);
376                         goto cleanup;
377                 }
378                 if (!prefixcmp(found_ref, "refs/remotes/")) {
379                         strbuf_addf(msg, "%s\t\tremote branch '%s' of .\n",
380                                     sha1_to_hex(branch_head), remote);
381                         goto cleanup;
382                 }
383         }
385         /* See if remote matches <name>^^^.. or <name>~<number> */
386         for (len = 0, ptr = remote + strlen(remote);
387              remote < ptr && ptr[-1] == '^';
388              ptr--)
389                 len++;
390         if (len)
391                 early = 1;
392         else {
393                 early = 0;
394                 ptr = strrchr(remote, '~');
395                 if (ptr) {
396                         int seen_nonzero = 0;
398                         len++; /* count ~ */
399                         while (*++ptr && isdigit(*ptr)) {
400                                 seen_nonzero |= (*ptr != '0');
401                                 len++;
402                         }
403                         if (*ptr)
404                                 len = 0; /* not ...~<number> */
405                         else if (seen_nonzero)
406                                 early = 1;
407                         else if (len == 1)
408                                 early = 1; /* "name~" is "name~1"! */
409                 }
410         }
411         if (len) {
412                 struct strbuf truname = STRBUF_INIT;
413                 strbuf_addstr(&truname, "refs/heads/");
414                 strbuf_addstr(&truname, remote);
415                 strbuf_setlen(&truname, truname.len - len);
416                 if (resolve_ref(truname.buf, buf_sha, 0, NULL)) {
417                         strbuf_addf(msg,
418                                     "%s\t\tbranch '%s'%s of .\n",
419                                     sha1_to_hex(remote_head->sha1),
420                                     truname.buf + 11,
421                                     (early ? " (early part)" : ""));
422                         strbuf_release(&truname);
423                         goto cleanup;
424                 }
425         }
427         if (!strcmp(remote, "FETCH_HEAD") &&
428                         !access(git_path("FETCH_HEAD"), R_OK)) {
429                 FILE *fp;
430                 struct strbuf line = STRBUF_INIT;
431                 char *ptr;
433                 fp = fopen(git_path("FETCH_HEAD"), "r");
434                 if (!fp)
435                         die_errno("could not open '%s' for reading",
436                                   git_path("FETCH_HEAD"));
437                 strbuf_getline(&line, fp, '\n');
438                 fclose(fp);
439                 ptr = strstr(line.buf, "\tnot-for-merge\t");
440                 if (ptr)
441                         strbuf_remove(&line, ptr-line.buf+1, 13);
442                 strbuf_addbuf(msg, &line);
443                 strbuf_release(&line);
444                 goto cleanup;
445         }
446         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
447                 sha1_to_hex(remote_head->sha1), remote);
448 cleanup:
449         strbuf_release(&buf);
450         strbuf_release(&bname);
453 static int git_merge_config(const char *k, const char *v, void *cb)
455         if (branch && !prefixcmp(k, "branch.") &&
456                 !prefixcmp(k + 7, branch) &&
457                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
458                 const char **argv;
459                 int argc;
460                 char *buf;
462                 buf = xstrdup(v);
463                 argc = split_cmdline(buf, &argv);
464                 if (argc < 0)
465                         die("Bad branch.%s.mergeoptions string", branch);
466                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
467                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
468                 argc++;
469                 parse_options(argc, argv, NULL, builtin_merge_options,
470                               builtin_merge_usage, 0);
471                 free(buf);
472         }
474         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
475                 show_diffstat = git_config_bool(k, v);
476         else if (!strcmp(k, "pull.twohead"))
477                 return git_config_string(&pull_twohead, k, v);
478         else if (!strcmp(k, "pull.octopus"))
479                 return git_config_string(&pull_octopus, k, v);
480         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
481                 option_log = git_config_bool(k, v);
482         return git_diff_ui_config(k, v, cb);
485 static int read_tree_trivial(unsigned char *common, unsigned char *head,
486                              unsigned char *one)
488         int i, nr_trees = 0;
489         struct tree *trees[MAX_UNPACK_TREES];
490         struct tree_desc t[MAX_UNPACK_TREES];
491         struct unpack_trees_options opts;
493         memset(&opts, 0, sizeof(opts));
494         opts.head_idx = 2;
495         opts.src_index = &the_index;
496         opts.dst_index = &the_index;
497         opts.update = 1;
498         opts.verbose_update = 1;
499         opts.trivial_merges_only = 1;
500         opts.merge = 1;
501         trees[nr_trees] = parse_tree_indirect(common);
502         if (!trees[nr_trees++])
503                 return -1;
504         trees[nr_trees] = parse_tree_indirect(head);
505         if (!trees[nr_trees++])
506                 return -1;
507         trees[nr_trees] = parse_tree_indirect(one);
508         if (!trees[nr_trees++])
509                 return -1;
510         opts.fn = threeway_merge;
511         cache_tree_free(&active_cache_tree);
512         for (i = 0; i < nr_trees; i++) {
513                 parse_tree(trees[i]);
514                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
515         }
516         if (unpack_trees(nr_trees, t, &opts))
517                 return -1;
518         return 0;
521 static void write_tree_trivial(unsigned char *sha1)
523         if (write_cache_as_tree(sha1, 0, NULL))
524                 die("git write-tree failed to write a tree");
527 static int try_merge_strategy(const char *strategy, struct commit_list *common,
528                               const char *head_arg)
530         const char **args;
531         int i = 0, ret;
532         struct commit_list *j;
533         struct strbuf buf = STRBUF_INIT;
534         int index_fd;
535         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
537         index_fd = hold_locked_index(lock, 1);
538         refresh_cache(REFRESH_QUIET);
539         if (active_cache_changed &&
540                         (write_cache(index_fd, active_cache, active_nr) ||
541                          commit_locked_index(lock)))
542                 return error("Unable to write index.");
543         rollback_lock_file(lock);
545         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
546                 int clean;
547                 struct commit *result;
548                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
549                 int index_fd;
550                 struct commit_list *reversed = NULL;
551                 struct merge_options o;
553                 if (remoteheads->next) {
554                         error("Not handling anything other than two heads merge.");
555                         return 2;
556                 }
558                 init_merge_options(&o);
559                 if (!strcmp(strategy, "subtree"))
560                         o.subtree_merge = 1;
562                 o.branch1 = head_arg;
563                 o.branch2 = remoteheads->item->util;
565                 for (j = common; j; j = j->next)
566                         commit_list_insert(j->item, &reversed);
568                 index_fd = hold_locked_index(lock, 1);
569                 clean = merge_recursive(&o, lookup_commit(head),
570                                 remoteheads->item, reversed, &result);
571                 if (active_cache_changed &&
572                                 (write_cache(index_fd, active_cache, active_nr) ||
573                                  commit_locked_index(lock)))
574                         die ("unable to write %s", get_index_file());
575                 rollback_lock_file(lock);
576                 return clean ? 0 : 1;
577         } else {
578                 args = xmalloc((4 + commit_list_count(common) +
579                                         commit_list_count(remoteheads)) * sizeof(char *));
580                 strbuf_addf(&buf, "merge-%s", strategy);
581                 args[i++] = buf.buf;
582                 for (j = common; j; j = j->next)
583                         args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
584                 args[i++] = "--";
585                 args[i++] = head_arg;
586                 for (j = remoteheads; j; j = j->next)
587                         args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
588                 args[i] = NULL;
589                 ret = run_command_v_opt(args, RUN_GIT_CMD);
590                 strbuf_release(&buf);
591                 i = 1;
592                 for (j = common; j; j = j->next)
593                         free((void *)args[i++]);
594                 i += 2;
595                 for (j = remoteheads; j; j = j->next)
596                         free((void *)args[i++]);
597                 free(args);
598                 discard_cache();
599                 if (read_cache() < 0)
600                         die("failed to read the cache");
601                 return ret;
602         }
605 static void count_diff_files(struct diff_queue_struct *q,
606                              struct diff_options *opt, void *data)
608         int *count = data;
610         (*count) += q->nr;
613 static int count_unmerged_entries(void)
615         const struct index_state *state = &the_index;
616         int i, ret = 0;
618         for (i = 0; i < state->cache_nr; i++)
619                 if (ce_stage(state->cache[i]))
620                         ret++;
622         return ret;
625 static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
627         struct tree *trees[MAX_UNPACK_TREES];
628         struct unpack_trees_options opts;
629         struct tree_desc t[MAX_UNPACK_TREES];
630         int i, fd, nr_trees = 0;
631         struct dir_struct dir;
632         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
634         refresh_cache(REFRESH_QUIET);
636         fd = hold_locked_index(lock_file, 1);
638         memset(&trees, 0, sizeof(trees));
639         memset(&opts, 0, sizeof(opts));
640         memset(&t, 0, sizeof(t));
641         memset(&dir, 0, sizeof(dir));
642         dir.flags |= DIR_SHOW_IGNORED;
643         dir.exclude_per_dir = ".gitignore";
644         opts.dir = &dir;
646         opts.head_idx = 1;
647         opts.src_index = &the_index;
648         opts.dst_index = &the_index;
649         opts.update = 1;
650         opts.verbose_update = 1;
651         opts.merge = 1;
652         opts.fn = twoway_merge;
654         trees[nr_trees] = parse_tree_indirect(head);
655         if (!trees[nr_trees++])
656                 return -1;
657         trees[nr_trees] = parse_tree_indirect(remote);
658         if (!trees[nr_trees++])
659                 return -1;
660         for (i = 0; i < nr_trees; i++) {
661                 parse_tree(trees[i]);
662                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
663         }
664         if (unpack_trees(nr_trees, t, &opts))
665                 return -1;
666         if (write_cache(fd, active_cache, active_nr) ||
667                 commit_locked_index(lock_file))
668                 die("unable to write new index file");
669         return 0;
672 static void split_merge_strategies(const char *string, struct strategy **list,
673                                    int *nr, int *alloc)
675         char *p, *q, *buf;
677         if (!string)
678                 return;
680         buf = xstrdup(string);
681         q = buf;
682         for (;;) {
683                 p = strchr(q, ' ');
684                 if (!p) {
685                         ALLOC_GROW(*list, *nr + 1, *alloc);
686                         (*list)[(*nr)++].name = xstrdup(q);
687                         free(buf);
688                         return;
689                 } else {
690                         *p = '\0';
691                         ALLOC_GROW(*list, *nr + 1, *alloc);
692                         (*list)[(*nr)++].name = xstrdup(q);
693                         q = ++p;
694                 }
695         }
698 static void add_strategies(const char *string, unsigned attr)
700         struct strategy *list = NULL;
701         int list_alloc = 0, list_nr = 0, i;
703         memset(&list, 0, sizeof(list));
704         split_merge_strategies(string, &list, &list_nr, &list_alloc);
705         if (list) {
706                 for (i = 0; i < list_nr; i++)
707                         append_strategy(get_strategy(list[i].name));
708                 return;
709         }
710         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
711                 if (all_strategy[i].attr & attr)
712                         append_strategy(&all_strategy[i]);
716 static int merge_trivial(void)
718         unsigned char result_tree[20], result_commit[20];
719         struct commit_list *parent = xmalloc(sizeof(*parent));
721         write_tree_trivial(result_tree);
722         printf("Wonderful.\n");
723         parent->item = lookup_commit(head);
724         parent->next = xmalloc(sizeof(*parent->next));
725         parent->next->item = remoteheads->item;
726         parent->next->next = NULL;
727         commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
728         finish(result_commit, "In-index merge");
729         drop_save();
730         return 0;
733 static int finish_automerge(struct commit_list *common,
734                             unsigned char *result_tree,
735                             const char *wt_strategy)
737         struct commit_list *parents = NULL, *j;
738         struct strbuf buf = STRBUF_INIT;
739         unsigned char result_commit[20];
741         free_commit_list(common);
742         if (allow_fast_forward) {
743                 parents = remoteheads;
744                 commit_list_insert(lookup_commit(head), &parents);
745                 parents = reduce_heads(parents);
746         } else {
747                 struct commit_list **pptr = &parents;
749                 pptr = &commit_list_insert(lookup_commit(head),
750                                 pptr)->next;
751                 for (j = remoteheads; j; j = j->next)
752                         pptr = &commit_list_insert(j->item, pptr)->next;
753         }
754         free_commit_list(remoteheads);
755         strbuf_addch(&merge_msg, '\n');
756         commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
757         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
758         finish(result_commit, buf.buf);
759         strbuf_release(&buf);
760         drop_save();
761         return 0;
764 static int suggest_conflicts(void)
766         FILE *fp;
767         int pos;
769         fp = fopen(git_path("MERGE_MSG"), "a");
770         if (!fp)
771                 die_errno("Could not open '%s' for writing",
772                           git_path("MERGE_MSG"));
773         fprintf(fp, "\nConflicts:\n");
774         for (pos = 0; pos < active_nr; pos++) {
775                 struct cache_entry *ce = active_cache[pos];
777                 if (ce_stage(ce)) {
778                         fprintf(fp, "\t%s\n", ce->name);
779                         while (pos + 1 < active_nr &&
780                                         !strcmp(ce->name,
781                                                 active_cache[pos + 1]->name))
782                                 pos++;
783                 }
784         }
785         fclose(fp);
786         rerere();
787         printf("Automatic merge failed; "
788                         "fix conflicts and then commit the result.\n");
789         return 1;
792 static struct commit *is_old_style_invocation(int argc, const char **argv)
794         struct commit *second_token = NULL;
795         if (argc > 1) {
796                 unsigned char second_sha1[20];
798                 if (get_sha1(argv[1], second_sha1))
799                         return NULL;
800                 second_token = lookup_commit_reference_gently(second_sha1, 0);
801                 if (!second_token)
802                         die("'%s' is not a commit", argv[1]);
803                 if (hashcmp(second_token->object.sha1, head))
804                         return NULL;
805         }
806         return second_token;
809 static int evaluate_result(void)
811         int cnt = 0;
812         struct rev_info rev;
814         /* Check how many files differ. */
815         init_revisions(&rev, "");
816         setup_revisions(0, NULL, &rev, NULL);
817         rev.diffopt.output_format |=
818                 DIFF_FORMAT_CALLBACK;
819         rev.diffopt.format_callback = count_diff_files;
820         rev.diffopt.format_callback_data = &cnt;
821         run_diff_files(&rev, 0);
823         /*
824          * Check how many unmerged entries are
825          * there.
826          */
827         cnt += count_unmerged_entries();
829         return cnt;
832 int cmd_merge(int argc, const char **argv, const char *prefix)
834         unsigned char result_tree[20];
835         struct strbuf buf = STRBUF_INIT;
836         const char *head_arg;
837         int flag, head_invalid = 0, i;
838         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
839         struct commit_list *common = NULL;
840         const char *best_strategy = NULL, *wt_strategy = NULL;
841         struct commit_list **remotes = &remoteheads;
843         setup_work_tree();
844         if (file_exists(git_path("MERGE_HEAD")))
845                 die("You have not concluded your merge. (MERGE_HEAD exists)");
846         if (read_cache_unmerged())
847                 die("You are in the middle of a conflicted merge."
848                                 " (index unmerged)");
850         /*
851          * Check if we are _not_ on a detached HEAD, i.e. if there is a
852          * current branch.
853          */
854         branch = resolve_ref("HEAD", head, 0, &flag);
855         if (branch && !prefixcmp(branch, "refs/heads/"))
856                 branch += 11;
857         if (is_null_sha1(head))
858                 head_invalid = 1;
860         git_config(git_merge_config, NULL);
862         /* for color.ui */
863         if (diff_use_color_default == -1)
864                 diff_use_color_default = git_use_color_default;
866         argc = parse_options(argc, argv, prefix, builtin_merge_options,
867                         builtin_merge_usage, 0);
868         if (verbosity < 0)
869                 show_diffstat = 0;
871         if (squash) {
872                 if (!allow_fast_forward)
873                         die("You cannot combine --squash with --no-ff.");
874                 option_commit = 0;
875         }
877         if (!argc)
878                 usage_with_options(builtin_merge_usage,
879                         builtin_merge_options);
881         /*
882          * This could be traditional "merge <msg> HEAD <commit>..."  and
883          * the way we can tell it is to see if the second token is HEAD,
884          * but some people might have misused the interface and used a
885          * committish that is the same as HEAD there instead.
886          * Traditional format never would have "-m" so it is an
887          * additional safety measure to check for it.
888          */
890         if (!have_message && is_old_style_invocation(argc, argv)) {
891                 strbuf_addstr(&merge_msg, argv[0]);
892                 head_arg = argv[1];
893                 argv += 2;
894                 argc -= 2;
895         } else if (head_invalid) {
896                 struct object *remote_head;
897                 /*
898                  * If the merged head is a valid one there is no reason
899                  * to forbid "git merge" into a branch yet to be born.
900                  * We do the same for "git pull".
901                  */
902                 if (argc != 1)
903                         die("Can merge only exactly one commit into "
904                                 "empty head");
905                 if (squash)
906                         die("Squash commit into empty head not supported yet");
907                 if (!allow_fast_forward)
908                         die("Non-fast-forward commit does not make sense into "
909                             "an empty head");
910                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
911                 if (!remote_head)
912                         die("%s - not something we can merge", argv[0]);
913                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
914                                 DIE_ON_ERR);
915                 reset_hard(remote_head->sha1, 0);
916                 return 0;
917         } else {
918                 struct strbuf msg = STRBUF_INIT;
920                 /* We are invoked directly as the first-class UI. */
921                 head_arg = "HEAD";
923                 /*
924                  * All the rest are the commits being merged;
925                  * prepare the standard merge summary message to
926                  * be appended to the given message.  If remote
927                  * is invalid we will die later in the common
928                  * codepath so we discard the error in this
929                  * loop.
930                  */
931                 for (i = 0; i < argc; i++)
932                         merge_name(argv[i], &msg);
933                 fmt_merge_msg(option_log, &msg, &merge_msg);
934                 if (merge_msg.len)
935                         strbuf_setlen(&merge_msg, merge_msg.len-1);
936         }
938         if (head_invalid || !argc)
939                 usage_with_options(builtin_merge_usage,
940                         builtin_merge_options);
942         strbuf_addstr(&buf, "merge");
943         for (i = 0; i < argc; i++)
944                 strbuf_addf(&buf, " %s", argv[i]);
945         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
946         strbuf_reset(&buf);
948         for (i = 0; i < argc; i++) {
949                 struct object *o;
950                 struct commit *commit;
952                 o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
953                 if (!o)
954                         die("%s - not something we can merge", argv[i]);
955                 commit = lookup_commit(o->sha1);
956                 commit->util = (void *)argv[i];
957                 remotes = &commit_list_insert(commit, remotes)->next;
959                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
960                 setenv(buf.buf, argv[i], 1);
961                 strbuf_reset(&buf);
962         }
964         if (!use_strategies) {
965                 if (!remoteheads->next)
966                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
967                 else
968                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
969         }
971         for (i = 0; i < use_strategies_nr; i++) {
972                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
973                         allow_fast_forward = 0;
974                 if (use_strategies[i]->attr & NO_TRIVIAL)
975                         allow_trivial = 0;
976         }
978         if (!remoteheads->next)
979                 common = get_merge_bases(lookup_commit(head),
980                                 remoteheads->item, 1);
981         else {
982                 struct commit_list *list = remoteheads;
983                 commit_list_insert(lookup_commit(head), &list);
984                 common = get_octopus_merge_bases(list);
985                 free(list);
986         }
988         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
989                 DIE_ON_ERR);
991         if (!common)
992                 ; /* No common ancestors found. We need a real merge. */
993         else if (!remoteheads->next && !common->next &&
994                         common->item == remoteheads->item) {
995                 /*
996                  * If head can reach all the merge then we are up to date.
997                  * but first the most common case of merging one remote.
998                  */
999                 finish_up_to_date("Already up-to-date.");
1000                 return 0;
1001         } else if (allow_fast_forward && !remoteheads->next &&
1002                         !common->next &&
1003                         !hashcmp(common->item->object.sha1, head)) {
1004                 /* Again the most common case of merging one remote. */
1005                 struct strbuf msg = STRBUF_INIT;
1006                 struct object *o;
1007                 char hex[41];
1009                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
1011                 if (verbosity >= 0)
1012                         printf("Updating %s..%s\n",
1013                                 hex,
1014                                 find_unique_abbrev(remoteheads->item->object.sha1,
1015                                 DEFAULT_ABBREV));
1016                 strbuf_addstr(&msg, "Fast forward");
1017                 if (have_message)
1018                         strbuf_addstr(&msg,
1019                                 " (no commit created; -m option ignored)");
1020                 o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
1021                         0, NULL, OBJ_COMMIT);
1022                 if (!o)
1023                         return 1;
1025                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
1026                         return 1;
1028                 finish(o->sha1, msg.buf);
1029                 drop_save();
1030                 return 0;
1031         } else if (!remoteheads->next && common->next)
1032                 ;
1033                 /*
1034                  * We are not doing octopus and not fast forward.  Need
1035                  * a real merge.
1036                  */
1037         else if (!remoteheads->next && !common->next && option_commit) {
1038                 /*
1039                  * We are not doing octopus, not fast forward, and have
1040                  * only one common.
1041                  */
1042                 refresh_cache(REFRESH_QUIET);
1043                 if (allow_trivial) {
1044                         /* See if it is really trivial. */
1045                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1046                         printf("Trying really trivial in-index merge...\n");
1047                         if (!read_tree_trivial(common->item->object.sha1,
1048                                         head, remoteheads->item->object.sha1))
1049                                 return merge_trivial();
1050                         printf("Nope.\n");
1051                 }
1052         } else {
1053                 /*
1054                  * An octopus.  If we can reach all the remote we are up
1055                  * to date.
1056                  */
1057                 int up_to_date = 1;
1058                 struct commit_list *j;
1060                 for (j = remoteheads; j; j = j->next) {
1061                         struct commit_list *common_one;
1063                         /*
1064                          * Here we *have* to calculate the individual
1065                          * merge_bases again, otherwise "git merge HEAD^
1066                          * HEAD^^" would be missed.
1067                          */
1068                         common_one = get_merge_bases(lookup_commit(head),
1069                                 j->item, 1);
1070                         if (hashcmp(common_one->item->object.sha1,
1071                                 j->item->object.sha1)) {
1072                                 up_to_date = 0;
1073                                 break;
1074                         }
1075                 }
1076                 if (up_to_date) {
1077                         finish_up_to_date("Already up-to-date. Yeeah!");
1078                         return 0;
1079                 }
1080         }
1082         /* We are going to make a new commit. */
1083         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1085         /*
1086          * At this point, we need a real merge.  No matter what strategy
1087          * we use, it would operate on the index, possibly affecting the
1088          * working tree, and when resolved cleanly, have the desired
1089          * tree in the index -- this means that the index must be in
1090          * sync with the head commit.  The strategies are responsible
1091          * to ensure this.
1092          */
1093         if (use_strategies_nr != 1) {
1094                 /*
1095                  * Stash away the local changes so that we can try more
1096                  * than one.
1097                  */
1098                 save_state();
1099         } else {
1100                 memcpy(stash, null_sha1, 20);
1101         }
1103         for (i = 0; i < use_strategies_nr; i++) {
1104                 int ret;
1105                 if (i) {
1106                         printf("Rewinding the tree to pristine...\n");
1107                         restore_state();
1108                 }
1109                 if (use_strategies_nr != 1)
1110                         printf("Trying merge strategy %s...\n",
1111                                 use_strategies[i]->name);
1112                 /*
1113                  * Remember which strategy left the state in the working
1114                  * tree.
1115                  */
1116                 wt_strategy = use_strategies[i]->name;
1118                 ret = try_merge_strategy(use_strategies[i]->name,
1119                         common, head_arg);
1120                 if (!option_commit && !ret) {
1121                         merge_was_ok = 1;
1122                         /*
1123                          * This is necessary here just to avoid writing
1124                          * the tree, but later we will *not* exit with
1125                          * status code 1 because merge_was_ok is set.
1126                          */
1127                         ret = 1;
1128                 }
1130                 if (ret) {
1131                         /*
1132                          * The backend exits with 1 when conflicts are
1133                          * left to be resolved, with 2 when it does not
1134                          * handle the given merge at all.
1135                          */
1136                         if (ret == 1) {
1137                                 int cnt = evaluate_result();
1139                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1140                                         best_strategy = use_strategies[i]->name;
1141                                         best_cnt = cnt;
1142                                 }
1143                         }
1144                         if (merge_was_ok)
1145                                 break;
1146                         else
1147                                 continue;
1148                 }
1150                 /* Automerge succeeded. */
1151                 write_tree_trivial(result_tree);
1152                 automerge_was_ok = 1;
1153                 break;
1154         }
1156         /*
1157          * If we have a resulting tree, that means the strategy module
1158          * auto resolved the merge cleanly.
1159          */
1160         if (automerge_was_ok)
1161                 return finish_automerge(common, result_tree, wt_strategy);
1163         /*
1164          * Pick the result from the best strategy and have the user fix
1165          * it up.
1166          */
1167         if (!best_strategy) {
1168                 restore_state();
1169                 if (use_strategies_nr > 1)
1170                         fprintf(stderr,
1171                                 "No merge strategy handled the merge.\n");
1172                 else
1173                         fprintf(stderr, "Merge with strategy %s failed.\n",
1174                                 use_strategies[0]->name);
1175                 return 2;
1176         } else if (best_strategy == wt_strategy)
1177                 ; /* We already have its result in the working tree. */
1178         else {
1179                 printf("Rewinding the tree to pristine...\n");
1180                 restore_state();
1181                 printf("Using the %s to prepare resolving by hand.\n",
1182                         best_strategy);
1183                 try_merge_strategy(best_strategy, common, head_arg);
1184         }
1186         if (squash)
1187                 finish(NULL, NULL);
1188         else {
1189                 int fd;
1190                 struct commit_list *j;
1192                 for (j = remoteheads; j; j = j->next)
1193                         strbuf_addf(&buf, "%s\n",
1194                                 sha1_to_hex(j->item->object.sha1));
1195                 fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1196                 if (fd < 0)
1197                         die_errno("Could not open '%s' for writing",
1198                                   git_path("MERGE_HEAD"));
1199                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1200                         die_errno("Could not write to '%s'", git_path("MERGE_HEAD"));
1201                 close(fd);
1202                 strbuf_addch(&merge_msg, '\n');
1203                 fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
1204                 if (fd < 0)
1205                         die_errno("Could not open '%s' for writing",
1206                                   git_path("MERGE_MSG"));
1207                 if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1208                         merge_msg.len)
1209                         die_errno("Could not write to '%s'", git_path("MERGE_MSG"));
1210                 close(fd);
1211                 fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
1212                 if (fd < 0)
1213                         die_errno("Could not open '%s' for writing",
1214                                   git_path("MERGE_MODE"));
1215                 strbuf_reset(&buf);
1216                 if (!allow_fast_forward)
1217                         strbuf_addf(&buf, "no-ff");
1218                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1219                         die_errno("Could not write to '%s'", git_path("MERGE_MODE"));
1220                 close(fd);
1221         }
1223         if (merge_was_ok) {
1224                 fprintf(stderr, "Automatic merge went well; "
1225                         "stopped before committing as requested\n");
1226                 return 0;
1227         } else
1228                 return suggest_conflicts();