Merge branch 'jn/maint-sequencer-fixes' into maint
[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 #include "resolve-undo.h"
28 #include "remote.h"
29
30 #define DEFAULT_TWOHEAD (1<<0)
31 #define DEFAULT_OCTOPUS (1<<1)
32 #define NO_FAST_FORWARD (1<<2)
33 #define NO_TRIVIAL      (1<<3)
34
35 struct strategy {
36         const char *name;
37         unsigned attr;
38 };
39
40 static const char * const builtin_merge_usage[] = {
41         "git merge [options] [<commit>...]",
42         "git merge [options] <msg> HEAD <commit>",
43         "git merge --abort",
44         NULL
45 };
46
47 static int show_diffstat = 1, shortlog_len, squash;
48 static int option_commit = 1, allow_fast_forward = 1;
49 static int fast_forward_only, option_edit;
50 static int allow_trivial = 1, have_message;
51 static struct strbuf merge_msg;
52 static struct commit_list *remoteheads;
53 static struct strategy **use_strategies;
54 static size_t use_strategies_nr, use_strategies_alloc;
55 static const char **xopts;
56 static size_t xopts_nr, xopts_alloc;
57 static const char *branch;
58 static char *branch_mergeoptions;
59 static int option_renormalize;
60 static int verbosity;
61 static int allow_rerere_auto;
62 static int abort_current_merge;
63 static int show_progress = -1;
64 static int default_to_upstream;
65
66 static struct strategy all_strategy[] = {
67         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
68         { "octopus",    DEFAULT_OCTOPUS },
69         { "resolve",    0 },
70         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
71         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
72 };
73
74 static const char *pull_twohead, *pull_octopus;
75
76 static int option_parse_message(const struct option *opt,
77                                 const char *arg, int unset)
78 {
79         struct strbuf *buf = opt->value;
80
81         if (unset)
82                 strbuf_setlen(buf, 0);
83         else if (arg) {
84                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
85                 have_message = 1;
86         } else
87                 return error(_("switch `m' requires a value"));
88         return 0;
89 }
90
91 static struct strategy *get_strategy(const char *name)
92 {
93         int i;
94         struct strategy *ret;
95         static struct cmdnames main_cmds, other_cmds;
96         static int loaded;
97
98         if (!name)
99                 return NULL;
100
101         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
102                 if (!strcmp(name, all_strategy[i].name))
103                         return &all_strategy[i];
104
105         if (!loaded) {
106                 struct cmdnames not_strategies;
107                 loaded = 1;
108
109                 memset(&not_strategies, 0, sizeof(struct cmdnames));
110                 load_command_list("git-merge-", &main_cmds, &other_cmds);
111                 for (i = 0; i < main_cmds.cnt; i++) {
112                         int j, found = 0;
113                         struct cmdname *ent = main_cmds.names[i];
114                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
115                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
116                                                 && !all_strategy[j].name[ent->len])
117                                         found = 1;
118                         if (!found)
119                                 add_cmdname(&not_strategies, ent->name, ent->len);
120                 }
121                 exclude_cmds(&main_cmds, &not_strategies);
122         }
123         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
124                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
125                 fprintf(stderr, _("Available strategies are:"));
126                 for (i = 0; i < main_cmds.cnt; i++)
127                         fprintf(stderr, " %s", main_cmds.names[i]->name);
128                 fprintf(stderr, ".\n");
129                 if (other_cmds.cnt) {
130                         fprintf(stderr, _("Available custom strategies are:"));
131                         for (i = 0; i < other_cmds.cnt; i++)
132                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
133                         fprintf(stderr, ".\n");
134                 }
135                 exit(1);
136         }
137
138         ret = xcalloc(1, sizeof(struct strategy));
139         ret->name = xstrdup(name);
140         ret->attr = NO_TRIVIAL;
141         return ret;
142 }
143
144 static void append_strategy(struct strategy *s)
145 {
146         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
147         use_strategies[use_strategies_nr++] = s;
148 }
149
150 static int option_parse_strategy(const struct option *opt,
151                                  const char *name, int unset)
152 {
153         if (unset)
154                 return 0;
155
156         append_strategy(get_strategy(name));
157         return 0;
158 }
159
160 static int option_parse_x(const struct option *opt,
161                           const char *arg, int unset)
162 {
163         if (unset)
164                 return 0;
165
166         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
167         xopts[xopts_nr++] = xstrdup(arg);
168         return 0;
169 }
170
171 static int option_parse_n(const struct option *opt,
172                           const char *arg, int unset)
173 {
174         show_diffstat = unset;
175         return 0;
176 }
177
178 static struct option builtin_merge_options[] = {
179         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
180                 "do not show a diffstat at the end of the merge",
181                 PARSE_OPT_NOARG, option_parse_n },
182         OPT_BOOLEAN(0, "stat", &show_diffstat,
183                 "show a diffstat at the end of the merge"),
184         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
185         { OPTION_INTEGER, 0, "log", &shortlog_len, "n",
186           "add (at most <n>) entries from shortlog to merge commit message",
187           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
188         OPT_BOOLEAN(0, "squash", &squash,
189                 "create a single commit instead of doing a merge"),
190         OPT_BOOLEAN(0, "commit", &option_commit,
191                 "perform a commit if the merge succeeds (default)"),
192         OPT_BOOLEAN('e', "edit", &option_edit,
193                 "edit message before committing"),
194         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
195                 "allow fast-forward (default)"),
196         OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
197                 "abort if fast-forward is not possible"),
198         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
199         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
200                 "merge strategy to use", option_parse_strategy),
201         OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
202                 "option for selected merge strategy", option_parse_x),
203         OPT_CALLBACK('m', "message", &merge_msg, "message",
204                 "merge commit message (for a non-fast-forward merge)",
205                 option_parse_message),
206         OPT__VERBOSITY(&verbosity),
207         OPT_BOOLEAN(0, "abort", &abort_current_merge,
208                 "abort the current in-progress merge"),
209         OPT_SET_INT(0, "progress", &show_progress, "force progress reporting", 1),
210         OPT_END()
211 };
212
213 /* Cleans up metadata that is uninteresting after a succeeded merge. */
214 static void drop_save(void)
215 {
216         unlink(git_path("MERGE_HEAD"));
217         unlink(git_path("MERGE_MSG"));
218         unlink(git_path("MERGE_MODE"));
219 }
220
221 static int save_state(unsigned char *stash)
222 {
223         int len;
224         struct child_process cp;
225         struct strbuf buffer = STRBUF_INIT;
226         const char *argv[] = {"stash", "create", NULL};
227
228         memset(&cp, 0, sizeof(cp));
229         cp.argv = argv;
230         cp.out = -1;
231         cp.git_cmd = 1;
232
233         if (start_command(&cp))
234                 die(_("could not run stash."));
235         len = strbuf_read(&buffer, cp.out, 1024);
236         close(cp.out);
237
238         if (finish_command(&cp) || len < 0)
239                 die(_("stash failed"));
240         else if (!len)          /* no changes */
241                 return -1;
242         strbuf_setlen(&buffer, buffer.len-1);
243         if (get_sha1(buffer.buf, stash))
244                 die(_("not a valid object: %s"), buffer.buf);
245         return 0;
246 }
247
248 static void read_empty(unsigned const char *sha1, int verbose)
249 {
250         int i = 0;
251         const char *args[7];
252
253         args[i++] = "read-tree";
254         if (verbose)
255                 args[i++] = "-v";
256         args[i++] = "-m";
257         args[i++] = "-u";
258         args[i++] = EMPTY_TREE_SHA1_HEX;
259         args[i++] = sha1_to_hex(sha1);
260         args[i] = NULL;
261
262         if (run_command_v_opt(args, RUN_GIT_CMD))
263                 die(_("read-tree failed"));
264 }
265
266 static void reset_hard(unsigned const char *sha1, int verbose)
267 {
268         int i = 0;
269         const char *args[6];
270
271         args[i++] = "read-tree";
272         if (verbose)
273                 args[i++] = "-v";
274         args[i++] = "--reset";
275         args[i++] = "-u";
276         args[i++] = sha1_to_hex(sha1);
277         args[i] = NULL;
278
279         if (run_command_v_opt(args, RUN_GIT_CMD))
280                 die(_("read-tree failed"));
281 }
282
283 static void restore_state(const unsigned char *head,
284                           const unsigned char *stash)
285 {
286         struct strbuf sb = STRBUF_INIT;
287         const char *args[] = { "stash", "apply", NULL, NULL };
288
289         if (is_null_sha1(stash))
290                 return;
291
292         reset_hard(head, 1);
293
294         args[2] = sha1_to_hex(stash);
295
296         /*
297          * It is OK to ignore error here, for example when there was
298          * nothing to restore.
299          */
300         run_command_v_opt(args, RUN_GIT_CMD);
301
302         strbuf_release(&sb);
303         refresh_cache(REFRESH_QUIET);
304 }
305
306 /* This is called when no merge was necessary. */
307 static void finish_up_to_date(const char *msg)
308 {
309         if (verbosity >= 0)
310                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
311         drop_save();
312 }
313
314 static void squash_message(struct commit *commit)
315 {
316         struct rev_info rev;
317         struct strbuf out = STRBUF_INIT;
318         struct commit_list *j;
319         const char *filename;
320         int fd;
321         struct pretty_print_context ctx = {0};
322
323         printf(_("Squash commit -- not updating HEAD\n"));
324         filename = git_path("SQUASH_MSG");
325         fd = open(filename, O_WRONLY | O_CREAT, 0666);
326         if (fd < 0)
327                 die_errno(_("Could not write to '%s'"), filename);
328
329         init_revisions(&rev, NULL);
330         rev.ignore_merges = 1;
331         rev.commit_format = CMIT_FMT_MEDIUM;
332
333         commit->object.flags |= UNINTERESTING;
334         add_pending_object(&rev, &commit->object, NULL);
335
336         for (j = remoteheads; j; j = j->next)
337                 add_pending_object(&rev, &j->item->object, NULL);
338
339         setup_revisions(0, NULL, &rev, NULL);
340         if (prepare_revision_walk(&rev))
341                 die(_("revision walk setup failed"));
342
343         ctx.abbrev = rev.abbrev;
344         ctx.date_mode = rev.date_mode;
345         ctx.fmt = rev.commit_format;
346
347         strbuf_addstr(&out, "Squashed commit of the following:\n");
348         while ((commit = get_revision(&rev)) != NULL) {
349                 strbuf_addch(&out, '\n');
350                 strbuf_addf(&out, "commit %s\n",
351                         sha1_to_hex(commit->object.sha1));
352                 pretty_print_commit(&ctx, commit, &out);
353         }
354         if (write(fd, out.buf, out.len) < 0)
355                 die_errno(_("Writing SQUASH_MSG"));
356         if (close(fd))
357                 die_errno(_("Finishing SQUASH_MSG"));
358         strbuf_release(&out);
359 }
360
361 static void finish(struct commit *head_commit,
362                    const unsigned char *new_head, const char *msg)
363 {
364         struct strbuf reflog_message = STRBUF_INIT;
365         const unsigned char *head = head_commit->object.sha1;
366
367         if (!msg)
368                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
369         else {
370                 if (verbosity >= 0)
371                         printf("%s\n", msg);
372                 strbuf_addf(&reflog_message, "%s: %s",
373                         getenv("GIT_REFLOG_ACTION"), msg);
374         }
375         if (squash) {
376                 squash_message(head_commit);
377         } else {
378                 if (verbosity >= 0 && !merge_msg.len)
379                         printf(_("No merge message -- not updating HEAD\n"));
380                 else {
381                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
382                         update_ref(reflog_message.buf, "HEAD",
383                                 new_head, head, 0,
384                                 DIE_ON_ERR);
385                         /*
386                          * We ignore errors in 'gc --auto', since the
387                          * user should see them.
388                          */
389                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
390                 }
391         }
392         if (new_head && show_diffstat) {
393                 struct diff_options opts;
394                 diff_setup(&opts);
395                 opts.output_format |=
396                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
397                 opts.detect_rename = DIFF_DETECT_RENAME;
398                 if (diff_setup_done(&opts) < 0)
399                         die(_("diff_setup_done failed"));
400                 diff_tree_sha1(head, new_head, "", &opts);
401                 diffcore_std(&opts);
402                 diff_flush(&opts);
403         }
404
405         /* Run a post-merge hook */
406         run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
407
408         strbuf_release(&reflog_message);
409 }
410
411 static struct object *want_commit(const char *name)
412 {
413         struct object *obj;
414         unsigned char sha1[20];
415         if (get_sha1(name, sha1))
416                 return NULL;
417         obj = parse_object(sha1);
418         return peel_to_type(name, 0, obj, OBJ_COMMIT);
419 }
420
421 /* Get the name for the merge commit's message. */
422 static void merge_name(const char *remote, struct strbuf *msg)
423 {
424         struct object *remote_head;
425         unsigned char branch_head[20], buf_sha[20];
426         struct strbuf buf = STRBUF_INIT;
427         struct strbuf bname = STRBUF_INIT;
428         const char *ptr;
429         char *found_ref;
430         int len, early;
431
432         strbuf_branchname(&bname, remote);
433         remote = bname.buf;
434
435         memset(branch_head, 0, sizeof(branch_head));
436         remote_head = want_commit(remote);
437         if (!remote_head)
438                 die(_("'%s' does not point to a commit"), remote);
439
440         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
441                 if (!prefixcmp(found_ref, "refs/heads/")) {
442                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
443                                     sha1_to_hex(branch_head), remote);
444                         goto cleanup;
445                 }
446                 if (!prefixcmp(found_ref, "refs/remotes/")) {
447                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
448                                     sha1_to_hex(branch_head), remote);
449                         goto cleanup;
450                 }
451         }
452
453         /* See if remote matches <name>^^^.. or <name>~<number> */
454         for (len = 0, ptr = remote + strlen(remote);
455              remote < ptr && ptr[-1] == '^';
456              ptr--)
457                 len++;
458         if (len)
459                 early = 1;
460         else {
461                 early = 0;
462                 ptr = strrchr(remote, '~');
463                 if (ptr) {
464                         int seen_nonzero = 0;
465
466                         len++; /* count ~ */
467                         while (*++ptr && isdigit(*ptr)) {
468                                 seen_nonzero |= (*ptr != '0');
469                                 len++;
470                         }
471                         if (*ptr)
472                                 len = 0; /* not ...~<number> */
473                         else if (seen_nonzero)
474                                 early = 1;
475                         else if (len == 1)
476                                 early = 1; /* "name~" is "name~1"! */
477                 }
478         }
479         if (len) {
480                 struct strbuf truname = STRBUF_INIT;
481                 strbuf_addstr(&truname, "refs/heads/");
482                 strbuf_addstr(&truname, remote);
483                 strbuf_setlen(&truname, truname.len - len);
484                 if (resolve_ref(truname.buf, buf_sha, 1, NULL)) {
485                         strbuf_addf(msg,
486                                     "%s\t\tbranch '%s'%s of .\n",
487                                     sha1_to_hex(remote_head->sha1),
488                                     truname.buf + 11,
489                                     (early ? " (early part)" : ""));
490                         strbuf_release(&truname);
491                         goto cleanup;
492                 }
493         }
494
495         if (!strcmp(remote, "FETCH_HEAD") &&
496                         !access(git_path("FETCH_HEAD"), R_OK)) {
497                 const char *filename;
498                 FILE *fp;
499                 struct strbuf line = STRBUF_INIT;
500                 char *ptr;
501
502                 filename = git_path("FETCH_HEAD");
503                 fp = fopen(filename, "r");
504                 if (!fp)
505                         die_errno(_("could not open '%s' for reading"),
506                                   filename);
507                 strbuf_getline(&line, fp, '\n');
508                 fclose(fp);
509                 ptr = strstr(line.buf, "\tnot-for-merge\t");
510                 if (ptr)
511                         strbuf_remove(&line, ptr-line.buf+1, 13);
512                 strbuf_addbuf(msg, &line);
513                 strbuf_release(&line);
514                 goto cleanup;
515         }
516         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
517                 sha1_to_hex(remote_head->sha1), remote);
518 cleanup:
519         strbuf_release(&buf);
520         strbuf_release(&bname);
521 }
522
523 static void parse_branch_merge_options(char *bmo)
524 {
525         const char **argv;
526         int argc;
527
528         if (!bmo)
529                 return;
530         argc = split_cmdline(bmo, &argv);
531         if (argc < 0)
532                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
533                     split_cmdline_strerror(argc));
534         argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
535         memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
536         argc++;
537         argv[0] = "branch.*.mergeoptions";
538         parse_options(argc, argv, NULL, builtin_merge_options,
539                       builtin_merge_usage, 0);
540         free(argv);
541 }
542
543 static int git_merge_config(const char *k, const char *v, void *cb)
544 {
545         if (branch && !prefixcmp(k, "branch.") &&
546                 !prefixcmp(k + 7, branch) &&
547                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
548                 free(branch_mergeoptions);
549                 branch_mergeoptions = xstrdup(v);
550                 return 0;
551         }
552
553         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
554                 show_diffstat = git_config_bool(k, v);
555         else if (!strcmp(k, "pull.twohead"))
556                 return git_config_string(&pull_twohead, k, v);
557         else if (!strcmp(k, "pull.octopus"))
558                 return git_config_string(&pull_octopus, k, v);
559         else if (!strcmp(k, "merge.renormalize"))
560                 option_renormalize = git_config_bool(k, v);
561         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary")) {
562                 int is_bool;
563                 shortlog_len = git_config_bool_or_int(k, v, &is_bool);
564                 if (!is_bool && shortlog_len < 0)
565                         return error(_("%s: negative length %s"), k, v);
566                 if (is_bool && shortlog_len)
567                         shortlog_len = DEFAULT_MERGE_LOG_LEN;
568                 return 0;
569         } else if (!strcmp(k, "merge.ff")) {
570                 int boolval = git_config_maybe_bool(k, v);
571                 if (0 <= boolval) {
572                         allow_fast_forward = boolval;
573                 } else if (v && !strcmp(v, "only")) {
574                         allow_fast_forward = 1;
575                         fast_forward_only = 1;
576                 } /* do not barf on values from future versions of git */
577                 return 0;
578         } else if (!strcmp(k, "merge.defaulttoupstream")) {
579                 default_to_upstream = git_config_bool(k, v);
580                 return 0;
581         }
582         return git_diff_ui_config(k, v, cb);
583 }
584
585 static int read_tree_trivial(unsigned char *common, unsigned char *head,
586                              unsigned char *one)
587 {
588         int i, nr_trees = 0;
589         struct tree *trees[MAX_UNPACK_TREES];
590         struct tree_desc t[MAX_UNPACK_TREES];
591         struct unpack_trees_options opts;
592
593         memset(&opts, 0, sizeof(opts));
594         opts.head_idx = 2;
595         opts.src_index = &the_index;
596         opts.dst_index = &the_index;
597         opts.update = 1;
598         opts.verbose_update = 1;
599         opts.trivial_merges_only = 1;
600         opts.merge = 1;
601         trees[nr_trees] = parse_tree_indirect(common);
602         if (!trees[nr_trees++])
603                 return -1;
604         trees[nr_trees] = parse_tree_indirect(head);
605         if (!trees[nr_trees++])
606                 return -1;
607         trees[nr_trees] = parse_tree_indirect(one);
608         if (!trees[nr_trees++])
609                 return -1;
610         opts.fn = threeway_merge;
611         cache_tree_free(&active_cache_tree);
612         for (i = 0; i < nr_trees; i++) {
613                 parse_tree(trees[i]);
614                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
615         }
616         if (unpack_trees(nr_trees, t, &opts))
617                 return -1;
618         return 0;
619 }
620
621 static void write_tree_trivial(unsigned char *sha1)
622 {
623         if (write_cache_as_tree(sha1, 0, NULL))
624                 die(_("git write-tree failed to write a tree"));
625 }
626
627 static const char *merge_argument(struct commit *commit)
628 {
629         if (commit)
630                 return sha1_to_hex(commit->object.sha1);
631         else
632                 return EMPTY_TREE_SHA1_HEX;
633 }
634
635 int try_merge_command(const char *strategy, size_t xopts_nr,
636                       const char **xopts, struct commit_list *common,
637                       const char *head_arg, struct commit_list *remotes)
638 {
639         const char **args;
640         int i = 0, x = 0, ret;
641         struct commit_list *j;
642         struct strbuf buf = STRBUF_INIT;
643
644         args = xmalloc((4 + xopts_nr + commit_list_count(common) +
645                         commit_list_count(remotes)) * sizeof(char *));
646         strbuf_addf(&buf, "merge-%s", strategy);
647         args[i++] = buf.buf;
648         for (x = 0; x < xopts_nr; x++) {
649                 char *s = xmalloc(strlen(xopts[x])+2+1);
650                 strcpy(s, "--");
651                 strcpy(s+2, xopts[x]);
652                 args[i++] = s;
653         }
654         for (j = common; j; j = j->next)
655                 args[i++] = xstrdup(merge_argument(j->item));
656         args[i++] = "--";
657         args[i++] = head_arg;
658         for (j = remotes; j; j = j->next)
659                 args[i++] = xstrdup(merge_argument(j->item));
660         args[i] = NULL;
661         ret = run_command_v_opt(args, RUN_GIT_CMD);
662         strbuf_release(&buf);
663         i = 1;
664         for (x = 0; x < xopts_nr; x++)
665                 free((void *)args[i++]);
666         for (j = common; j; j = j->next)
667                 free((void *)args[i++]);
668         i += 2;
669         for (j = remotes; j; j = j->next)
670                 free((void *)args[i++]);
671         free(args);
672         discard_cache();
673         if (read_cache() < 0)
674                 die(_("failed to read the cache"));
675         resolve_undo_clear();
676
677         return ret;
678 }
679
680 static int try_merge_strategy(const char *strategy, struct commit_list *common,
681                               struct commit *head, const char *head_arg)
682 {
683         int index_fd;
684         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
685
686         index_fd = hold_locked_index(lock, 1);
687         refresh_cache(REFRESH_QUIET);
688         if (active_cache_changed &&
689                         (write_cache(index_fd, active_cache, active_nr) ||
690                          commit_locked_index(lock)))
691                 return error(_("Unable to write index."));
692         rollback_lock_file(lock);
693
694         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
695                 int clean, x;
696                 struct commit *result;
697                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
698                 int index_fd;
699                 struct commit_list *reversed = NULL;
700                 struct merge_options o;
701                 struct commit_list *j;
702
703                 if (remoteheads->next) {
704                         error(_("Not handling anything other than two heads merge."));
705                         return 2;
706                 }
707
708                 init_merge_options(&o);
709                 if (!strcmp(strategy, "subtree"))
710                         o.subtree_shift = "";
711
712                 o.renormalize = option_renormalize;
713                 o.show_rename_progress =
714                         show_progress == -1 ? isatty(2) : show_progress;
715
716                 for (x = 0; x < xopts_nr; x++)
717                         if (parse_merge_opt(&o, xopts[x]))
718                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
719
720                 o.branch1 = head_arg;
721                 o.branch2 = remoteheads->item->util;
722
723                 for (j = common; j; j = j->next)
724                         commit_list_insert(j->item, &reversed);
725
726                 index_fd = hold_locked_index(lock, 1);
727                 clean = merge_recursive(&o, head,
728                                 remoteheads->item, reversed, &result);
729                 if (active_cache_changed &&
730                                 (write_cache(index_fd, active_cache, active_nr) ||
731                                  commit_locked_index(lock)))
732                         die (_("unable to write %s"), get_index_file());
733                 rollback_lock_file(lock);
734                 return clean ? 0 : 1;
735         } else {
736                 return try_merge_command(strategy, xopts_nr, xopts,
737                                                 common, head_arg, remoteheads);
738         }
739 }
740
741 static void count_diff_files(struct diff_queue_struct *q,
742                              struct diff_options *opt, void *data)
743 {
744         int *count = data;
745
746         (*count) += q->nr;
747 }
748
749 static int count_unmerged_entries(void)
750 {
751         int i, ret = 0;
752
753         for (i = 0; i < active_nr; i++)
754                 if (ce_stage(active_cache[i]))
755                         ret++;
756
757         return ret;
758 }
759
760 int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
761 {
762         struct tree *trees[MAX_UNPACK_TREES];
763         struct unpack_trees_options opts;
764         struct tree_desc t[MAX_UNPACK_TREES];
765         int i, fd, nr_trees = 0;
766         struct dir_struct dir;
767         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
768
769         refresh_cache(REFRESH_QUIET);
770
771         fd = hold_locked_index(lock_file, 1);
772
773         memset(&trees, 0, sizeof(trees));
774         memset(&opts, 0, sizeof(opts));
775         memset(&t, 0, sizeof(t));
776         memset(&dir, 0, sizeof(dir));
777         dir.flags |= DIR_SHOW_IGNORED;
778         setup_standard_excludes(&dir);
779         opts.dir = &dir;
780
781         opts.head_idx = 1;
782         opts.src_index = &the_index;
783         opts.dst_index = &the_index;
784         opts.update = 1;
785         opts.verbose_update = 1;
786         opts.merge = 1;
787         opts.fn = twoway_merge;
788         setup_unpack_trees_porcelain(&opts, "merge");
789
790         trees[nr_trees] = parse_tree_indirect(head);
791         if (!trees[nr_trees++])
792                 return -1;
793         trees[nr_trees] = parse_tree_indirect(remote);
794         if (!trees[nr_trees++])
795                 return -1;
796         for (i = 0; i < nr_trees; i++) {
797                 parse_tree(trees[i]);
798                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
799         }
800         if (unpack_trees(nr_trees, t, &opts))
801                 return -1;
802         if (write_cache(fd, active_cache, active_nr) ||
803                 commit_locked_index(lock_file))
804                 die(_("unable to write new index file"));
805         return 0;
806 }
807
808 static void split_merge_strategies(const char *string, struct strategy **list,
809                                    int *nr, int *alloc)
810 {
811         char *p, *q, *buf;
812
813         if (!string)
814                 return;
815
816         buf = xstrdup(string);
817         q = buf;
818         for (;;) {
819                 p = strchr(q, ' ');
820                 if (!p) {
821                         ALLOC_GROW(*list, *nr + 1, *alloc);
822                         (*list)[(*nr)++].name = xstrdup(q);
823                         free(buf);
824                         return;
825                 } else {
826                         *p = '\0';
827                         ALLOC_GROW(*list, *nr + 1, *alloc);
828                         (*list)[(*nr)++].name = xstrdup(q);
829                         q = ++p;
830                 }
831         }
832 }
833
834 static void add_strategies(const char *string, unsigned attr)
835 {
836         struct strategy *list = NULL;
837         int list_alloc = 0, list_nr = 0, i;
838
839         memset(&list, 0, sizeof(list));
840         split_merge_strategies(string, &list, &list_nr, &list_alloc);
841         if (list) {
842                 for (i = 0; i < list_nr; i++)
843                         append_strategy(get_strategy(list[i].name));
844                 return;
845         }
846         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
847                 if (all_strategy[i].attr & attr)
848                         append_strategy(&all_strategy[i]);
849
850 }
851
852 static void write_merge_msg(struct strbuf *msg)
853 {
854         const char *filename = git_path("MERGE_MSG");
855         int fd = open(filename, O_WRONLY | O_CREAT, 0666);
856         if (fd < 0)
857                 die_errno(_("Could not open '%s' for writing"),
858                           filename);
859         if (write_in_full(fd, msg->buf, msg->len) != msg->len)
860                 die_errno(_("Could not write to '%s'"), filename);
861         close(fd);
862 }
863
864 static void read_merge_msg(struct strbuf *msg)
865 {
866         const char *filename = git_path("MERGE_MSG");
867         strbuf_reset(msg);
868         if (strbuf_read_file(msg, filename, 0) < 0)
869                 die_errno(_("Could not read from '%s'"), filename);
870 }
871
872 static void write_merge_state(void);
873 static void abort_commit(const char *err_msg)
874 {
875         if (err_msg)
876                 error("%s", err_msg);
877         fprintf(stderr,
878                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
879         write_merge_state();
880         exit(1);
881 }
882
883 static void prepare_to_commit(void)
884 {
885         struct strbuf msg = STRBUF_INIT;
886         strbuf_addbuf(&msg, &merge_msg);
887         strbuf_addch(&msg, '\n');
888         write_merge_msg(&msg);
889         run_hook(get_index_file(), "prepare-commit-msg",
890                  git_path("MERGE_MSG"), "merge", NULL, NULL);
891         if (option_edit) {
892                 if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
893                         abort_commit(NULL);
894         }
895         read_merge_msg(&msg);
896         stripspace(&msg, option_edit);
897         if (!msg.len)
898                 abort_commit(_("Empty commit message."));
899         strbuf_release(&merge_msg);
900         strbuf_addbuf(&merge_msg, &msg);
901         strbuf_release(&msg);
902 }
903
904 static int merge_trivial(struct commit *head)
905 {
906         unsigned char result_tree[20], result_commit[20];
907         struct commit_list *parent = xmalloc(sizeof(*parent));
908
909         write_tree_trivial(result_tree);
910         printf(_("Wonderful.\n"));
911         parent->item = head;
912         parent->next = xmalloc(sizeof(*parent->next));
913         parent->next->item = remoteheads->item;
914         parent->next->next = NULL;
915         prepare_to_commit();
916         commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
917         finish(head, result_commit, "In-index merge");
918         drop_save();
919         return 0;
920 }
921
922 static int finish_automerge(struct commit *head,
923                             struct commit_list *common,
924                             unsigned char *result_tree,
925                             const char *wt_strategy)
926 {
927         struct commit_list *parents = NULL, *j;
928         struct strbuf buf = STRBUF_INIT;
929         unsigned char result_commit[20];
930
931         free_commit_list(common);
932         if (allow_fast_forward) {
933                 parents = remoteheads;
934                 commit_list_insert(head, &parents);
935                 parents = reduce_heads(parents);
936         } else {
937                 struct commit_list **pptr = &parents;
938
939                 pptr = &commit_list_insert(head,
940                                 pptr)->next;
941                 for (j = remoteheads; j; j = j->next)
942                         pptr = &commit_list_insert(j->item, pptr)->next;
943         }
944         strbuf_addch(&merge_msg, '\n');
945         prepare_to_commit();
946         free_commit_list(remoteheads);
947         commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
948         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
949         finish(head, result_commit, buf.buf);
950         strbuf_release(&buf);
951         drop_save();
952         return 0;
953 }
954
955 static int suggest_conflicts(int renormalizing)
956 {
957         const char *filename;
958         FILE *fp;
959         int pos;
960
961         filename = git_path("MERGE_MSG");
962         fp = fopen(filename, "a");
963         if (!fp)
964                 die_errno(_("Could not open '%s' for writing"), filename);
965         fprintf(fp, "\nConflicts:\n");
966         for (pos = 0; pos < active_nr; pos++) {
967                 struct cache_entry *ce = active_cache[pos];
968
969                 if (ce_stage(ce)) {
970                         fprintf(fp, "\t%s\n", ce->name);
971                         while (pos + 1 < active_nr &&
972                                         !strcmp(ce->name,
973                                                 active_cache[pos + 1]->name))
974                                 pos++;
975                 }
976         }
977         fclose(fp);
978         rerere(allow_rerere_auto);
979         printf(_("Automatic merge failed; "
980                         "fix conflicts and then commit the result.\n"));
981         return 1;
982 }
983
984 static struct commit *is_old_style_invocation(int argc, const char **argv,
985                                               const unsigned char *head)
986 {
987         struct commit *second_token = NULL;
988         if (argc > 2) {
989                 unsigned char second_sha1[20];
990
991                 if (get_sha1(argv[1], second_sha1))
992                         return NULL;
993                 second_token = lookup_commit_reference_gently(second_sha1, 0);
994                 if (!second_token)
995                         die(_("'%s' is not a commit"), argv[1]);
996                 if (hashcmp(second_token->object.sha1, head))
997                         return NULL;
998         }
999         return second_token;
1000 }
1001
1002 static int evaluate_result(void)
1003 {
1004         int cnt = 0;
1005         struct rev_info rev;
1006
1007         /* Check how many files differ. */
1008         init_revisions(&rev, "");
1009         setup_revisions(0, NULL, &rev, NULL);
1010         rev.diffopt.output_format |=
1011                 DIFF_FORMAT_CALLBACK;
1012         rev.diffopt.format_callback = count_diff_files;
1013         rev.diffopt.format_callback_data = &cnt;
1014         run_diff_files(&rev, 0);
1015
1016         /*
1017          * Check how many unmerged entries are
1018          * there.
1019          */
1020         cnt += count_unmerged_entries();
1021
1022         return cnt;
1023 }
1024
1025 /*
1026  * Pretend as if the user told us to merge with the tracking
1027  * branch we have for the upstream of the current branch
1028  */
1029 static int setup_with_upstream(const char ***argv)
1030 {
1031         struct branch *branch = branch_get(NULL);
1032         int i;
1033         const char **args;
1034
1035         if (!branch)
1036                 die(_("No current branch."));
1037         if (!branch->remote)
1038                 die(_("No remote for the current branch."));
1039         if (!branch->merge_nr)
1040                 die(_("No default upstream defined for the current branch."));
1041
1042         args = xcalloc(branch->merge_nr + 1, sizeof(char *));
1043         for (i = 0; i < branch->merge_nr; i++) {
1044                 if (!branch->merge[i]->dst)
1045                         die(_("No remote tracking branch for %s from %s"),
1046                             branch->merge[i]->src, branch->remote_name);
1047                 args[i] = branch->merge[i]->dst;
1048         }
1049         args[i] = NULL;
1050         *argv = args;
1051         return i;
1052 }
1053
1054 static void write_merge_state(void)
1055 {
1056         const char *filename;
1057         int fd;
1058         struct commit_list *j;
1059         struct strbuf buf = STRBUF_INIT;
1060
1061         for (j = remoteheads; j; j = j->next)
1062                 strbuf_addf(&buf, "%s\n",
1063                         sha1_to_hex(j->item->object.sha1));
1064         filename = git_path("MERGE_HEAD");
1065         fd = open(filename, O_WRONLY | O_CREAT, 0666);
1066         if (fd < 0)
1067                 die_errno(_("Could not open '%s' for writing"), filename);
1068         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1069                 die_errno(_("Could not write to '%s'"), filename);
1070         close(fd);
1071         strbuf_addch(&merge_msg, '\n');
1072         write_merge_msg(&merge_msg);
1073
1074         filename = git_path("MERGE_MODE");
1075         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
1076         if (fd < 0)
1077                 die_errno(_("Could not open '%s' for writing"), filename);
1078         strbuf_reset(&buf);
1079         if (!allow_fast_forward)
1080                 strbuf_addf(&buf, "no-ff");
1081         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1082                 die_errno(_("Could not write to '%s'"), filename);
1083         close(fd);
1084 }
1085
1086 int cmd_merge(int argc, const char **argv, const char *prefix)
1087 {
1088         unsigned char result_tree[20];
1089         unsigned char stash[20];
1090         unsigned char head_sha1[20];
1091         struct commit *head_commit;
1092         struct strbuf buf = STRBUF_INIT;
1093         const char *head_arg;
1094         int flag, i;
1095         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1096         struct commit_list *common = NULL;
1097         const char *best_strategy = NULL, *wt_strategy = NULL;
1098         struct commit_list **remotes = &remoteheads;
1099
1100         if (argc == 2 && !strcmp(argv[1], "-h"))
1101                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1102
1103         /*
1104          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1105          * current branch.
1106          */
1107         branch = resolve_ref("HEAD", head_sha1, 0, &flag);
1108         if (branch && !prefixcmp(branch, "refs/heads/"))
1109                 branch += 11;
1110         if (!branch || is_null_sha1(head_sha1))
1111                 head_commit = NULL;
1112         else
1113                 head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1114
1115         git_config(git_merge_config, NULL);
1116
1117         if (branch_mergeoptions)
1118                 parse_branch_merge_options(branch_mergeoptions);
1119         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1120                         builtin_merge_usage, 0);
1121
1122         if (verbosity < 0 && show_progress == -1)
1123                 show_progress = 0;
1124
1125         if (abort_current_merge) {
1126                 int nargc = 2;
1127                 const char *nargv[] = {"reset", "--merge", NULL};
1128
1129                 if (!file_exists(git_path("MERGE_HEAD")))
1130                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1131
1132                 /* Invoke 'git reset --merge' */
1133                 return cmd_reset(nargc, nargv, prefix);
1134         }
1135
1136         if (read_cache_unmerged())
1137                 die_resolve_conflict("merge");
1138
1139         if (file_exists(git_path("MERGE_HEAD"))) {
1140                 /*
1141                  * There is no unmerged entry, don't advise 'git
1142                  * add/rm <file>', just 'git commit'.
1143                  */
1144                 if (advice_resolve_conflict)
1145                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1146                                   "Please, commit your changes before you can merge."));
1147                 else
1148                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1149         }
1150         if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1151                 if (advice_resolve_conflict)
1152                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1153                             "Please, commit your changes before you can merge."));
1154                 else
1155                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1156         }
1157         resolve_undo_clear();
1158
1159         if (verbosity < 0)
1160                 show_diffstat = 0;
1161
1162         if (squash) {
1163                 if (!allow_fast_forward)
1164                         die(_("You cannot combine --squash with --no-ff."));
1165                 option_commit = 0;
1166         }
1167
1168         if (!allow_fast_forward && fast_forward_only)
1169                 die(_("You cannot combine --no-ff with --ff-only."));
1170
1171         if (!abort_current_merge) {
1172                 if (!argc && default_to_upstream)
1173                         argc = setup_with_upstream(&argv);
1174                 else if (argc == 1 && !strcmp(argv[0], "-"))
1175                         argv[0] = "@{-1}";
1176         }
1177         if (!argc)
1178                 usage_with_options(builtin_merge_usage,
1179                         builtin_merge_options);
1180
1181         /*
1182          * This could be traditional "merge <msg> HEAD <commit>..."  and
1183          * the way we can tell it is to see if the second token is HEAD,
1184          * but some people might have misused the interface and used a
1185          * committish that is the same as HEAD there instead.
1186          * Traditional format never would have "-m" so it is an
1187          * additional safety measure to check for it.
1188          */
1189
1190         if (!have_message && head_commit &&
1191             is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
1192                 strbuf_addstr(&merge_msg, argv[0]);
1193                 head_arg = argv[1];
1194                 argv += 2;
1195                 argc -= 2;
1196         } else if (!head_commit) {
1197                 struct object *remote_head;
1198                 /*
1199                  * If the merged head is a valid one there is no reason
1200                  * to forbid "git merge" into a branch yet to be born.
1201                  * We do the same for "git pull".
1202                  */
1203                 if (argc != 1)
1204                         die(_("Can merge only exactly one commit into "
1205                                 "empty head"));
1206                 if (squash)
1207                         die(_("Squash commit into empty head not supported yet"));
1208                 if (!allow_fast_forward)
1209                         die(_("Non-fast-forward commit does not make sense into "
1210                             "an empty head"));
1211                 remote_head = want_commit(argv[0]);
1212                 if (!remote_head)
1213                         die(_("%s - not something we can merge"), argv[0]);
1214                 read_empty(remote_head->sha1, 0);
1215                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
1216                                 DIE_ON_ERR);
1217                 return 0;
1218         } else {
1219                 struct strbuf merge_names = STRBUF_INIT;
1220
1221                 /* We are invoked directly as the first-class UI. */
1222                 head_arg = "HEAD";
1223
1224                 /*
1225                  * All the rest are the commits being merged;
1226                  * prepare the standard merge summary message to
1227                  * be appended to the given message.  If remote
1228                  * is invalid we will die later in the common
1229                  * codepath so we discard the error in this
1230                  * loop.
1231                  */
1232                 for (i = 0; i < argc; i++)
1233                         merge_name(argv[i], &merge_names);
1234
1235                 if (!have_message || shortlog_len) {
1236                         fmt_merge_msg(&merge_names, &merge_msg, !have_message,
1237                                       shortlog_len);
1238                         if (merge_msg.len)
1239                                 strbuf_setlen(&merge_msg, merge_msg.len - 1);
1240                 }
1241         }
1242
1243         if (!head_commit || !argc)
1244                 usage_with_options(builtin_merge_usage,
1245                         builtin_merge_options);
1246
1247         strbuf_addstr(&buf, "merge");
1248         for (i = 0; i < argc; i++)
1249                 strbuf_addf(&buf, " %s", argv[i]);
1250         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1251         strbuf_reset(&buf);
1252
1253         for (i = 0; i < argc; i++) {
1254                 struct object *o;
1255                 struct commit *commit;
1256
1257                 o = want_commit(argv[i]);
1258                 if (!o)
1259                         die(_("%s - not something we can merge"), argv[i]);
1260                 commit = lookup_commit(o->sha1);
1261                 commit->util = (void *)argv[i];
1262                 remotes = &commit_list_insert(commit, remotes)->next;
1263
1264                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
1265                 setenv(buf.buf, argv[i], 1);
1266                 strbuf_reset(&buf);
1267         }
1268
1269         if (!use_strategies) {
1270                 if (!remoteheads->next)
1271                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1272                 else
1273                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1274         }
1275
1276         for (i = 0; i < use_strategies_nr; i++) {
1277                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1278                         allow_fast_forward = 0;
1279                 if (use_strategies[i]->attr & NO_TRIVIAL)
1280                         allow_trivial = 0;
1281         }
1282
1283         if (!remoteheads->next)
1284                 common = get_merge_bases(head_commit, remoteheads->item, 1);
1285         else {
1286                 struct commit_list *list = remoteheads;
1287                 commit_list_insert(head_commit, &list);
1288                 common = get_octopus_merge_bases(list);
1289                 free(list);
1290         }
1291
1292         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
1293                    NULL, 0, DIE_ON_ERR);
1294
1295         if (!common)
1296                 ; /* No common ancestors found. We need a real merge. */
1297         else if (!remoteheads->next && !common->next &&
1298                         common->item == remoteheads->item) {
1299                 /*
1300                  * If head can reach all the merge then we are up to date.
1301                  * but first the most common case of merging one remote.
1302                  */
1303                 finish_up_to_date("Already up-to-date.");
1304                 return 0;
1305         } else if (allow_fast_forward && !remoteheads->next &&
1306                         !common->next &&
1307                         !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
1308                 /* Again the most common case of merging one remote. */
1309                 struct strbuf msg = STRBUF_INIT;
1310                 struct object *o;
1311                 char hex[41];
1312
1313                 strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
1314
1315                 if (verbosity >= 0)
1316                         printf(_("Updating %s..%s\n"),
1317                                 hex,
1318                                 find_unique_abbrev(remoteheads->item->object.sha1,
1319                                 DEFAULT_ABBREV));
1320                 strbuf_addstr(&msg, "Fast-forward");
1321                 if (have_message)
1322                         strbuf_addstr(&msg,
1323                                 " (no commit created; -m option ignored)");
1324                 o = want_commit(sha1_to_hex(remoteheads->item->object.sha1));
1325                 if (!o)
1326                         return 1;
1327
1328                 if (checkout_fast_forward(head_commit->object.sha1, remoteheads->item->object.sha1))
1329                         return 1;
1330
1331                 finish(head_commit, o->sha1, msg.buf);
1332                 drop_save();
1333                 return 0;
1334         } else if (!remoteheads->next && common->next)
1335                 ;
1336                 /*
1337                  * We are not doing octopus and not fast-forward.  Need
1338                  * a real merge.
1339                  */
1340         else if (!remoteheads->next && !common->next && option_commit) {
1341                 /*
1342                  * We are not doing octopus, not fast-forward, and have
1343                  * only one common.
1344                  */
1345                 refresh_cache(REFRESH_QUIET);
1346                 if (allow_trivial && !fast_forward_only) {
1347                         /* See if it is really trivial. */
1348                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1349                         printf(_("Trying really trivial in-index merge...\n"));
1350                         if (!read_tree_trivial(common->item->object.sha1,
1351                                         head_commit->object.sha1, remoteheads->item->object.sha1))
1352                                 return merge_trivial(head_commit);
1353                         printf(_("Nope.\n"));
1354                 }
1355         } else {
1356                 /*
1357                  * An octopus.  If we can reach all the remote we are up
1358                  * to date.
1359                  */
1360                 int up_to_date = 1;
1361                 struct commit_list *j;
1362
1363                 for (j = remoteheads; j; j = j->next) {
1364                         struct commit_list *common_one;
1365
1366                         /*
1367                          * Here we *have* to calculate the individual
1368                          * merge_bases again, otherwise "git merge HEAD^
1369                          * HEAD^^" would be missed.
1370                          */
1371                         common_one = get_merge_bases(head_commit, j->item, 1);
1372                         if (hashcmp(common_one->item->object.sha1,
1373                                 j->item->object.sha1)) {
1374                                 up_to_date = 0;
1375                                 break;
1376                         }
1377                 }
1378                 if (up_to_date) {
1379                         finish_up_to_date("Already up-to-date. Yeeah!");
1380                         return 0;
1381                 }
1382         }
1383
1384         if (fast_forward_only)
1385                 die(_("Not possible to fast-forward, aborting."));
1386
1387         /* We are going to make a new commit. */
1388         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1389
1390         /*
1391          * At this point, we need a real merge.  No matter what strategy
1392          * we use, it would operate on the index, possibly affecting the
1393          * working tree, and when resolved cleanly, have the desired
1394          * tree in the index -- this means that the index must be in
1395          * sync with the head commit.  The strategies are responsible
1396          * to ensure this.
1397          */
1398         if (use_strategies_nr == 1 ||
1399             /*
1400              * Stash away the local changes so that we can try more than one.
1401              */
1402             save_state(stash))
1403                 hashcpy(stash, null_sha1);
1404
1405         for (i = 0; i < use_strategies_nr; i++) {
1406                 int ret;
1407                 if (i) {
1408                         printf(_("Rewinding the tree to pristine...\n"));
1409                         restore_state(head_commit->object.sha1, stash);
1410                 }
1411                 if (use_strategies_nr != 1)
1412                         printf(_("Trying merge strategy %s...\n"),
1413                                 use_strategies[i]->name);
1414                 /*
1415                  * Remember which strategy left the state in the working
1416                  * tree.
1417                  */
1418                 wt_strategy = use_strategies[i]->name;
1419
1420                 ret = try_merge_strategy(use_strategies[i]->name,
1421                                          common, head_commit, head_arg);
1422                 if (!option_commit && !ret) {
1423                         merge_was_ok = 1;
1424                         /*
1425                          * This is necessary here just to avoid writing
1426                          * the tree, but later we will *not* exit with
1427                          * status code 1 because merge_was_ok is set.
1428                          */
1429                         ret = 1;
1430                 }
1431
1432                 if (ret) {
1433                         /*
1434                          * The backend exits with 1 when conflicts are
1435                          * left to be resolved, with 2 when it does not
1436                          * handle the given merge at all.
1437                          */
1438                         if (ret == 1) {
1439                                 int cnt = evaluate_result();
1440
1441                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1442                                         best_strategy = use_strategies[i]->name;
1443                                         best_cnt = cnt;
1444                                 }
1445                         }
1446                         if (merge_was_ok)
1447                                 break;
1448                         else
1449                                 continue;
1450                 }
1451
1452                 /* Automerge succeeded. */
1453                 write_tree_trivial(result_tree);
1454                 automerge_was_ok = 1;
1455                 break;
1456         }
1457
1458         /*
1459          * If we have a resulting tree, that means the strategy module
1460          * auto resolved the merge cleanly.
1461          */
1462         if (automerge_was_ok)
1463                 return finish_automerge(head_commit, common, result_tree,
1464                                         wt_strategy);
1465
1466         /*
1467          * Pick the result from the best strategy and have the user fix
1468          * it up.
1469          */
1470         if (!best_strategy) {
1471                 restore_state(head_commit->object.sha1, stash);
1472                 if (use_strategies_nr > 1)
1473                         fprintf(stderr,
1474                                 _("No merge strategy handled the merge.\n"));
1475                 else
1476                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1477                                 use_strategies[0]->name);
1478                 return 2;
1479         } else if (best_strategy == wt_strategy)
1480                 ; /* We already have its result in the working tree. */
1481         else {
1482                 printf(_("Rewinding the tree to pristine...\n"));
1483                 restore_state(head_commit->object.sha1, stash);
1484                 printf(_("Using the %s to prepare resolving by hand.\n"),
1485                         best_strategy);
1486                 try_merge_strategy(best_strategy, common, head_commit, head_arg);
1487         }
1488
1489         if (squash)
1490                 finish(head_commit, NULL, NULL);
1491         else
1492                 write_merge_state();
1493
1494         if (merge_was_ok) {
1495                 fprintf(stderr, _("Automatic merge went well; "
1496                         "stopped before committing as requested\n"));
1497                 return 0;
1498         } else
1499                 return suggest_conflicts(option_renormalize);
1500 }