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