merge-recursive: get rid of virtual_id
[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
54 static struct strategy all_strategy[] = {
55         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
56         { "octopus",    DEFAULT_OCTOPUS },
57         { "resolve",    0 },
58         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
59         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
60 };
61
62 static const char *pull_twohead, *pull_octopus;
63
64 static int option_parse_message(const struct option *opt,
65                                 const char *arg, int unset)
66 {
67         struct strbuf *buf = opt->value;
68
69         if (unset)
70                 strbuf_setlen(buf, 0);
71         else if (arg) {
72                 strbuf_addf(buf, "%s\n\n", arg);
73                 have_message = 1;
74         } else
75                 return error("switch `m' requires a value");
76         return 0;
77 }
78
79 static struct strategy *get_strategy(const char *name)
80 {
81         int i;
82         struct strategy *ret;
83         static struct cmdnames main_cmds, other_cmds;
84         static int loaded;
85
86         if (!name)
87                 return NULL;
88
89         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
90                 if (!strcmp(name, all_strategy[i].name))
91                         return &all_strategy[i];
92
93         if (!loaded) {
94                 struct cmdnames not_strategies;
95                 loaded = 1;
96
97                 memset(&not_strategies, 0, sizeof(struct cmdnames));
98                 load_command_list("git-merge-", &main_cmds, &other_cmds);
99                 for (i = 0; i < main_cmds.cnt; i++) {
100                         int j, found = 0;
101                         struct cmdname *ent = main_cmds.names[i];
102                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
103                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
104                                                 && !all_strategy[j].name[ent->len])
105                                         found = 1;
106                         if (!found)
107                                 add_cmdname(&not_strategies, ent->name, ent->len);
108                         exclude_cmds(&main_cmds, &not_strategies);
109                 }
110         }
111         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
112                 fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
113                 fprintf(stderr, "Available strategies are:");
114                 for (i = 0; i < main_cmds.cnt; i++)
115                         fprintf(stderr, " %s", main_cmds.names[i]->name);
116                 fprintf(stderr, ".\n");
117                 if (other_cmds.cnt) {
118                         fprintf(stderr, "Available custom strategies are:");
119                         for (i = 0; i < other_cmds.cnt; i++)
120                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
121                         fprintf(stderr, ".\n");
122                 }
123                 exit(1);
124         }
125
126         ret = xmalloc(sizeof(struct strategy));
127         memset(ret, 0, 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_END()
176 };
177
178 /* Cleans up metadata that is uninteresting after a succeeded merge. */
179 static void drop_save(void)
180 {
181         unlink(git_path("MERGE_HEAD"));
182         unlink(git_path("MERGE_MSG"));
183 }
184
185 static void save_state(void)
186 {
187         int len;
188         struct child_process cp;
189         struct strbuf buffer = STRBUF_INIT;
190         const char *argv[] = {"stash", "create", NULL};
191
192         memset(&cp, 0, sizeof(cp));
193         cp.argv = argv;
194         cp.out = -1;
195         cp.git_cmd = 1;
196
197         if (start_command(&cp))
198                 die("could not run stash.");
199         len = strbuf_read(&buffer, cp.out, 1024);
200         close(cp.out);
201
202         if (finish_command(&cp) || len < 0)
203                 die("stash failed");
204         else if (!len)
205                 return;
206         strbuf_setlen(&buffer, buffer.len-1);
207         if (get_sha1(buffer.buf, stash))
208                 die("not a valid object: %s", buffer.buf);
209 }
210
211 static void reset_hard(unsigned const char *sha1, int verbose)
212 {
213         int i = 0;
214         const char *args[6];
215
216         args[i++] = "read-tree";
217         if (verbose)
218                 args[i++] = "-v";
219         args[i++] = "--reset";
220         args[i++] = "-u";
221         args[i++] = sha1_to_hex(sha1);
222         args[i] = NULL;
223
224         if (run_command_v_opt(args, RUN_GIT_CMD))
225                 die("read-tree failed");
226 }
227
228 static void restore_state(void)
229 {
230         struct strbuf sb;
231         const char *args[] = { "stash", "apply", NULL, NULL };
232
233         if (is_null_sha1(stash))
234                 return;
235
236         reset_hard(head, 1);
237
238         strbuf_init(&sb, 0);
239         args[2] = sha1_to_hex(stash);
240
241         /*
242          * It is OK to ignore error here, for example when there was
243          * nothing to restore.
244          */
245         run_command_v_opt(args, RUN_GIT_CMD);
246
247         strbuf_release(&sb);
248         refresh_cache(REFRESH_QUIET);
249 }
250
251 /* This is called when no merge was necessary. */
252 static void finish_up_to_date(const char *msg)
253 {
254         printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
255         drop_save();
256 }
257
258 static void squash_message(void)
259 {
260         struct rev_info rev;
261         struct commit *commit;
262         struct strbuf out;
263         struct commit_list *j;
264         int fd;
265
266         printf("Squash commit -- not updating HEAD\n");
267         fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
268         if (fd < 0)
269                 die("Could not write to %s", git_path("SQUASH_MSG"));
270
271         init_revisions(&rev, NULL);
272         rev.ignore_merges = 1;
273         rev.commit_format = CMIT_FMT_MEDIUM;
274
275         commit = lookup_commit(head);
276         commit->object.flags |= UNINTERESTING;
277         add_pending_object(&rev, &commit->object, NULL);
278
279         for (j = remoteheads; j; j = j->next)
280                 add_pending_object(&rev, &j->item->object, NULL);
281
282         setup_revisions(0, NULL, &rev, NULL);
283         if (prepare_revision_walk(&rev))
284                 die("revision walk setup failed");
285
286         strbuf_init(&out, 0);
287         strbuf_addstr(&out, "Squashed commit of the following:\n");
288         while ((commit = get_revision(&rev)) != NULL) {
289                 strbuf_addch(&out, '\n');
290                 strbuf_addf(&out, "commit %s\n",
291                         sha1_to_hex(commit->object.sha1));
292                 pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
293                         NULL, NULL, rev.date_mode, 0);
294         }
295         write(fd, out.buf, out.len);
296         close(fd);
297         strbuf_release(&out);
298 }
299
300 static int run_hook(const char *name)
301 {
302         struct child_process hook;
303         const char *argv[3], *env[2];
304         char index[PATH_MAX];
305
306         argv[0] = git_path("hooks/%s", name);
307         if (access(argv[0], X_OK) < 0)
308                 return 0;
309
310         snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
311         env[0] = index;
312         env[1] = NULL;
313
314         if (squash)
315                 argv[1] = "1";
316         else
317                 argv[1] = "0";
318         argv[2] = NULL;
319
320         memset(&hook, 0, sizeof(hook));
321         hook.argv = argv;
322         hook.no_stdin = 1;
323         hook.stdout_to_stderr = 1;
324         hook.env = env;
325
326         return run_command(&hook);
327 }
328
329 static void finish(const unsigned char *new_head, const char *msg)
330 {
331         struct strbuf reflog_message;
332
333         strbuf_init(&reflog_message, 0);
334         if (!msg)
335                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
336         else {
337                 printf("%s\n", msg);
338                 strbuf_addf(&reflog_message, "%s: %s",
339                         getenv("GIT_REFLOG_ACTION"), msg);
340         }
341         if (squash) {
342                 squash_message();
343         } else {
344                 if (!merge_msg.len)
345                         printf("No merge message -- not updating HEAD\n");
346                 else {
347                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
348                         update_ref(reflog_message.buf, "HEAD",
349                                 new_head, head, 0,
350                                 DIE_ON_ERR);
351                         /*
352                          * We ignore errors in 'gc --auto', since the
353                          * user should see them.
354                          */
355                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
356                 }
357         }
358         if (new_head && show_diffstat) {
359                 struct diff_options opts;
360                 diff_setup(&opts);
361                 opts.output_format |=
362                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
363                 opts.detect_rename = DIFF_DETECT_RENAME;
364                 if (diff_use_color_default > 0)
365                         DIFF_OPT_SET(&opts, COLOR_DIFF);
366                 if (diff_setup_done(&opts) < 0)
367                         die("diff_setup_done failed");
368                 diff_tree_sha1(head, new_head, "", &opts);
369                 diffcore_std(&opts);
370                 diff_flush(&opts);
371         }
372
373         /* Run a post-merge hook */
374         run_hook("post-merge");
375
376         strbuf_release(&reflog_message);
377 }
378
379 /* Get the name for the merge commit's message. */
380 static void merge_name(const char *remote, struct strbuf *msg)
381 {
382         struct object *remote_head;
383         unsigned char branch_head[20], buf_sha[20];
384         struct strbuf buf;
385         const char *ptr;
386         int len, early;
387
388         memset(branch_head, 0, sizeof(branch_head));
389         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
390         if (!remote_head)
391                 die("'%s' does not point to a commit", remote);
392
393         strbuf_init(&buf, 0);
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;
449                 char *ptr;
450
451                 strbuf_init(&line, 0);
452                 fp = fopen(git_path("FETCH_HEAD"), "r");
453                 if (!fp)
454                         die("could not open %s for reading: %s",
455                                 git_path("FETCH_HEAD"), strerror(errno));
456                 strbuf_getline(&line, fp, '\n');
457                 fclose(fp);
458                 ptr = strstr(line.buf, "\tnot-for-merge\t");
459                 if (ptr)
460                         strbuf_remove(&line, ptr-line.buf+1, 13);
461                 strbuf_addbuf(msg, &line);
462                 strbuf_release(&line);
463                 return;
464         }
465         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
466                 sha1_to_hex(remote_head->sha1), remote);
467 }
468
469 static int git_merge_config(const char *k, const char *v, void *cb)
470 {
471         if (branch && !prefixcmp(k, "branch.") &&
472                 !prefixcmp(k + 7, branch) &&
473                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
474                 const char **argv;
475                 int argc;
476                 char *buf;
477
478                 buf = xstrdup(v);
479                 argc = split_cmdline(buf, &argv);
480                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
481                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
482                 argc++;
483                 parse_options(argc, argv, builtin_merge_options,
484                               builtin_merge_usage, 0);
485                 free(buf);
486         }
487
488         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
489                 show_diffstat = git_config_bool(k, v);
490         else if (!strcmp(k, "pull.twohead"))
491                 return git_config_string(&pull_twohead, k, v);
492         else if (!strcmp(k, "pull.octopus"))
493                 return git_config_string(&pull_octopus, k, v);
494         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
495                 option_log = git_config_bool(k, v);
496         return git_diff_ui_config(k, v, cb);
497 }
498
499 static int read_tree_trivial(unsigned char *common, unsigned char *head,
500                              unsigned char *one)
501 {
502         int i, nr_trees = 0;
503         struct tree *trees[MAX_UNPACK_TREES];
504         struct tree_desc t[MAX_UNPACK_TREES];
505         struct unpack_trees_options opts;
506
507         memset(&opts, 0, sizeof(opts));
508         opts.head_idx = 2;
509         opts.src_index = &the_index;
510         opts.dst_index = &the_index;
511         opts.update = 1;
512         opts.verbose_update = 1;
513         opts.trivial_merges_only = 1;
514         opts.merge = 1;
515         trees[nr_trees] = parse_tree_indirect(common);
516         if (!trees[nr_trees++])
517                 return -1;
518         trees[nr_trees] = parse_tree_indirect(head);
519         if (!trees[nr_trees++])
520                 return -1;
521         trees[nr_trees] = parse_tree_indirect(one);
522         if (!trees[nr_trees++])
523                 return -1;
524         opts.fn = threeway_merge;
525         cache_tree_free(&active_cache_tree);
526         for (i = 0; i < nr_trees; i++) {
527                 parse_tree(trees[i]);
528                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
529         }
530         if (unpack_trees(nr_trees, t, &opts))
531                 return -1;
532         return 0;
533 }
534
535 static void write_tree_trivial(unsigned char *sha1)
536 {
537         if (write_cache_as_tree(sha1, 0, NULL))
538                 die("git write-tree failed to write a tree");
539 }
540
541 static int try_merge_strategy(const char *strategy, struct commit_list *common,
542                               const char *head_arg)
543 {
544         const char **args;
545         int i = 0, ret;
546         struct commit_list *j;
547         struct strbuf buf;
548
549         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
550                 int clean;
551                 struct commit *result;
552                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
553                 int index_fd;
554                 struct commit_list *reversed = NULL;
555                 struct merge_options o;
556
557                 if (remoteheads->next) {
558                         error("Not handling anything other than two heads merge.");
559                         return 2;
560                 }
561
562                 init_merge_options(&o);
563                 if (!strcmp(strategy, "subtree"))
564                         o.subtree_merge = 1;
565
566                 o.branch1 = head_arg;
567                 o.branch2 = remoteheads->item->util;
568
569                 for (j = common; j; j = j->next)
570                         commit_list_insert(j->item, &reversed);
571
572                 index_fd = hold_locked_index(lock, 1);
573                 clean = merge_recursive(&o, lookup_commit(head),
574                                 remoteheads->item, reversed, &result);
575                 if (active_cache_changed &&
576                                 (write_cache(index_fd, active_cache, active_nr) ||
577                                  commit_locked_index(lock)))
578                         die ("unable to write %s", get_index_file());
579                 return clean ? 0 : 1;
580         } else {
581                 args = xmalloc((4 + commit_list_count(common) +
582                                         commit_list_count(remoteheads)) * sizeof(char *));
583                 strbuf_init(&buf, 0);
584                 strbuf_addf(&buf, "merge-%s", strategy);
585                 args[i++] = buf.buf;
586                 for (j = common; j; j = j->next)
587                         args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
588                 args[i++] = "--";
589                 args[i++] = head_arg;
590                 for (j = remoteheads; j; j = j->next)
591                         args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
592                 args[i] = NULL;
593                 ret = run_command_v_opt(args, RUN_GIT_CMD);
594                 strbuf_release(&buf);
595                 i = 1;
596                 for (j = common; j; j = j->next)
597                         free((void *)args[i++]);
598                 i += 2;
599                 for (j = remoteheads; j; j = j->next)
600                         free((void *)args[i++]);
601                 free(args);
602                 discard_cache();
603                 if (read_cache() < 0)
604                         die("failed to read the cache");
605                 return -ret;
606         }
607 }
608
609 static void count_diff_files(struct diff_queue_struct *q,
610                              struct diff_options *opt, void *data)
611 {
612         int *count = data;
613
614         (*count) += q->nr;
615 }
616
617 static int count_unmerged_entries(void)
618 {
619         const struct index_state *state = &the_index;
620         int i, ret = 0;
621
622         for (i = 0; i < state->cache_nr; i++)
623                 if (ce_stage(state->cache[i]))
624                         ret++;
625
626         return ret;
627 }
628
629 static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
630 {
631         struct tree *trees[MAX_UNPACK_TREES];
632         struct unpack_trees_options opts;
633         struct tree_desc t[MAX_UNPACK_TREES];
634         int i, fd, nr_trees = 0;
635         struct dir_struct dir;
636         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
637
638         refresh_cache(REFRESH_QUIET);
639
640         fd = hold_locked_index(lock_file, 1);
641
642         memset(&trees, 0, sizeof(trees));
643         memset(&opts, 0, sizeof(opts));
644         memset(&t, 0, sizeof(t));
645         memset(&dir, 0, sizeof(dir));
646         dir.show_ignored = 1;
647         dir.exclude_per_dir = ".gitignore";
648         opts.dir = &dir;
649
650         opts.head_idx = 1;
651         opts.src_index = &the_index;
652         opts.dst_index = &the_index;
653         opts.update = 1;
654         opts.verbose_update = 1;
655         opts.merge = 1;
656         opts.fn = twoway_merge;
657
658         trees[nr_trees] = parse_tree_indirect(head);
659         if (!trees[nr_trees++])
660                 return -1;
661         trees[nr_trees] = parse_tree_indirect(remote);
662         if (!trees[nr_trees++])
663                 return -1;
664         for (i = 0; i < nr_trees; i++) {
665                 parse_tree(trees[i]);
666                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
667         }
668         if (unpack_trees(nr_trees, t, &opts))
669                 return -1;
670         if (write_cache(fd, active_cache, active_nr) ||
671                 commit_locked_index(lock_file))
672                 die("unable to write new index file");
673         return 0;
674 }
675
676 static void split_merge_strategies(const char *string, struct strategy **list,
677                                    int *nr, int *alloc)
678 {
679         char *p, *q, *buf;
680
681         if (!string)
682                 return;
683
684         buf = xstrdup(string);
685         q = buf;
686         for (;;) {
687                 p = strchr(q, ' ');
688                 if (!p) {
689                         ALLOC_GROW(*list, *nr + 1, *alloc);
690                         (*list)[(*nr)++].name = xstrdup(q);
691                         free(buf);
692                         return;
693                 } else {
694                         *p = '\0';
695                         ALLOC_GROW(*list, *nr + 1, *alloc);
696                         (*list)[(*nr)++].name = xstrdup(q);
697                         q = ++p;
698                 }
699         }
700 }
701
702 static void add_strategies(const char *string, unsigned attr)
703 {
704         struct strategy *list = NULL;
705         int list_alloc = 0, list_nr = 0, i;
706
707         memset(&list, 0, sizeof(list));
708         split_merge_strategies(string, &list, &list_nr, &list_alloc);
709         if (list) {
710                 for (i = 0; i < list_nr; i++)
711                         append_strategy(get_strategy(list[i].name));
712                 return;
713         }
714         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
715                 if (all_strategy[i].attr & attr)
716                         append_strategy(&all_strategy[i]);
717
718 }
719
720 static int merge_trivial(void)
721 {
722         unsigned char result_tree[20], result_commit[20];
723         struct commit_list *parent = xmalloc(sizeof(struct commit_list *));
724
725         write_tree_trivial(result_tree);
726         printf("Wonderful.\n");
727         parent->item = lookup_commit(head);
728         parent->next = xmalloc(sizeof(struct commit_list *));
729         parent->next->item = remoteheads->item;
730         parent->next->next = NULL;
731         commit_tree(merge_msg.buf, result_tree, parent, result_commit);
732         finish(result_commit, "In-index merge");
733         drop_save();
734         return 0;
735 }
736
737 static int finish_automerge(struct commit_list *common,
738                             unsigned char *result_tree,
739                             const char *wt_strategy)
740 {
741         struct commit_list *parents = NULL, *j;
742         struct strbuf buf = STRBUF_INIT;
743         unsigned char result_commit[20];
744
745         free_commit_list(common);
746         if (allow_fast_forward) {
747                 parents = remoteheads;
748                 commit_list_insert(lookup_commit(head), &parents);
749                 parents = reduce_heads(parents);
750         } else {
751                 struct commit_list **pptr = &parents;
752
753                 pptr = &commit_list_insert(lookup_commit(head),
754                                 pptr)->next;
755                 for (j = remoteheads; j; j = j->next)
756                         pptr = &commit_list_insert(j->item, pptr)->next;
757         }
758         free_commit_list(remoteheads);
759         strbuf_addch(&merge_msg, '\n');
760         commit_tree(merge_msg.buf, result_tree, parents, result_commit);
761         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
762         finish(result_commit, buf.buf);
763         strbuf_release(&buf);
764         drop_save();
765         return 0;
766 }
767
768 static int suggest_conflicts(void)
769 {
770         FILE *fp;
771         int pos;
772
773         fp = fopen(git_path("MERGE_MSG"), "a");
774         if (!fp)
775                 die("Could open %s for writing", git_path("MERGE_MSG"));
776         fprintf(fp, "\nConflicts:\n");
777         for (pos = 0; pos < active_nr; pos++) {
778                 struct cache_entry *ce = active_cache[pos];
779
780                 if (ce_stage(ce)) {
781                         fprintf(fp, "\t%s\n", ce->name);
782                         while (pos + 1 < active_nr &&
783                                         !strcmp(ce->name,
784                                                 active_cache[pos + 1]->name))
785                                 pos++;
786                 }
787         }
788         fclose(fp);
789         rerere();
790         printf("Automatic merge failed; "
791                         "fix conflicts and then commit the result.\n");
792         return 1;
793 }
794
795 static struct commit *is_old_style_invocation(int argc, const char **argv)
796 {
797         struct commit *second_token = NULL;
798         if (argc > 1) {
799                 unsigned char second_sha1[20];
800
801                 if (get_sha1(argv[1], second_sha1))
802                         return NULL;
803                 second_token = lookup_commit_reference_gently(second_sha1, 0);
804                 if (!second_token)
805                         die("'%s' is not a commit", argv[1]);
806                 if (hashcmp(second_token->object.sha1, head))
807                         return NULL;
808         }
809         return second_token;
810 }
811
812 static int evaluate_result(void)
813 {
814         int cnt = 0;
815         struct rev_info rev;
816
817         /* Check how many files differ. */
818         init_revisions(&rev, "");
819         setup_revisions(0, NULL, &rev, NULL);
820         rev.diffopt.output_format |=
821                 DIFF_FORMAT_CALLBACK;
822         rev.diffopt.format_callback = count_diff_files;
823         rev.diffopt.format_callback_data = &cnt;
824         run_diff_files(&rev, 0);
825
826         /*
827          * Check how many unmerged entries are
828          * there.
829          */
830         cnt += count_unmerged_entries();
831
832         return cnt;
833 }
834
835 int cmd_merge(int argc, const char **argv, const char *prefix)
836 {
837         unsigned char result_tree[20];
838         struct strbuf buf;
839         const char *head_arg;
840         int flag, head_invalid = 0, i;
841         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
842         struct commit_list *common = NULL;
843         const char *best_strategy = NULL, *wt_strategy = NULL;
844         struct commit_list **remotes = &remoteheads;
845
846         setup_work_tree();
847         if (read_cache_unmerged())
848                 die("You are in the middle of a conflicted merge.");
849
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;
859
860         git_config(git_merge_config, NULL);
861
862         /* for color.ui */
863         if (diff_use_color_default == -1)
864                 diff_use_color_default = git_use_color_default;
865
866         argc = parse_options(argc, argv, builtin_merge_options,
867                         builtin_merge_usage, 0);
868
869         if (squash) {
870                 if (!allow_fast_forward)
871                         die("You cannot combine --squash with --no-ff.");
872                 option_commit = 0;
873         }
874
875         if (!argc)
876                 usage_with_options(builtin_merge_usage,
877                         builtin_merge_options);
878
879         /*
880          * This could be traditional "merge <msg> HEAD <commit>..."  and
881          * the way we can tell it is to see if the second token is HEAD,
882          * but some people might have misused the interface and used a
883          * committish that is the same as HEAD there instead.
884          * Traditional format never would have "-m" so it is an
885          * additional safety measure to check for it.
886          */
887         strbuf_init(&buf, 0);
888
889         if (!have_message && is_old_style_invocation(argc, argv)) {
890                 strbuf_addstr(&merge_msg, argv[0]);
891                 head_arg = argv[1];
892                 argv += 2;
893                 argc -= 2;
894         } else if (head_invalid) {
895                 struct object *remote_head;
896                 /*
897                  * If the merged head is a valid one there is no reason
898                  * to forbid "git merge" into a branch yet to be born.
899                  * We do the same for "git pull".
900                  */
901                 if (argc != 1)
902                         die("Can merge only exactly one commit into "
903                                 "empty head");
904                 if (squash)
905                         die("Squash commit into empty head not supported yet");
906                 if (!allow_fast_forward)
907                         die("Non-fast-forward commit does not make sense into "
908                             "an empty head");
909                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
910                 if (!remote_head)
911                         die("%s - not something we can merge", argv[0]);
912                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
913                                 DIE_ON_ERR);
914                 reset_hard(remote_head->sha1, 0);
915                 return 0;
916         } else {
917                 struct strbuf msg;
918
919                 /* We are invoked directly as the first-class UI. */
920                 head_arg = "HEAD";
921
922                 /*
923                  * All the rest are the commits being merged;
924                  * prepare the standard merge summary message to
925                  * be appended to the given message.  If remote
926                  * is invalid we will die later in the common
927                  * codepath so we discard the error in this
928                  * loop.
929                  */
930                 strbuf_init(&msg, 0);
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         }
937
938         if (head_invalid || !argc)
939                 usage_with_options(builtin_merge_usage,
940                         builtin_merge_options);
941
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);
947
948         for (i = 0; i < argc; i++) {
949                 struct object *o;
950                 struct commit *commit;
951
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;
958
959                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
960                 setenv(buf.buf, argv[i], 1);
961                 strbuf_reset(&buf);
962         }
963
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         }
970
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         }
977
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         }
987
988         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
989                 DIE_ON_ERR);
990
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;
1006                 struct object *o;
1007                 char hex[41];
1008
1009                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
1010
1011                 printf("Updating %s..%s\n",
1012                         hex,
1013                         find_unique_abbrev(remoteheads->item->object.sha1,
1014                         DEFAULT_ABBREV));
1015                 strbuf_init(&msg, 0);
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;
1024
1025                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
1026                         return 1;
1027
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;
1059
1060                 for (j = remoteheads; j; j = j->next) {
1061                         struct commit_list *common_one;
1062
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         }
1081
1082         /* We are going to make a new commit. */
1083         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1084
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         }
1102
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;
1117
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                 }
1129
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();
1138
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                 }
1149
1150                 /* Automerge succeeded. */
1151                 write_tree_trivial(result_tree);
1152                 automerge_was_ok = 1;
1153                 break;
1154         }
1155
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);
1162
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         }
1185
1186         if (squash)
1187                 finish(NULL, NULL);
1188         else {
1189                 int fd;
1190                 struct commit_list *j;
1191
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("Could open %s for writing",
1198                                 git_path("MERGE_HEAD"));
1199                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1200                         die("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("Could open %s for writing", git_path("MERGE_MSG"));
1206                 if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1207                         merge_msg.len)
1208                         die("Could not write to %s", git_path("MERGE_MSG"));
1209                 close(fd);
1210         }
1211
1212         if (merge_was_ok) {
1213                 fprintf(stderr, "Automatic merge went well; "
1214                         "stopped before committing as requested\n");
1215                 return 0;
1216         } else
1217                 return suggest_conflicts();
1218 }