Merge branch 'ly/mktree-using-strbuf'
[git] / builtin / revert.c
1 #include "cache.h"
2 #include "builtin.h"
3 #include "object.h"
4 #include "commit.h"
5 #include "tag.h"
6 #include "run-command.h"
7 #include "exec_cmd.h"
8 #include "utf8.h"
9 #include "parse-options.h"
10 #include "cache-tree.h"
11 #include "diff.h"
12 #include "revision.h"
13 #include "rerere.h"
14 #include "merge-recursive.h"
15 #include "refs.h"
16 #include "dir.h"
17 #include "sequencer.h"
18
19 /*
20  * This implements the builtins revert and cherry-pick.
21  *
22  * Copyright (c) 2007 Johannes E. Schindelin
23  *
24  * Based on git-revert.sh, which is
25  *
26  * Copyright (c) 2005 Linus Torvalds
27  * Copyright (c) 2005 Junio C Hamano
28  */
29
30 static const char * const revert_usage[] = {
31         "git revert [options] <commit-ish>",
32         "git revert <subcommand>",
33         NULL
34 };
35
36 static const char * const cherry_pick_usage[] = {
37         "git cherry-pick [options] <commit-ish>",
38         "git cherry-pick <subcommand>",
39         NULL
40 };
41
42 enum replay_action { REVERT, CHERRY_PICK };
43 enum replay_subcommand { REPLAY_NONE, REPLAY_RESET, REPLAY_CONTINUE };
44
45 struct replay_opts {
46         enum replay_action action;
47         enum replay_subcommand subcommand;
48
49         /* Boolean options */
50         int edit;
51         int record_origin;
52         int no_commit;
53         int signoff;
54         int allow_ff;
55         int allow_rerere_auto;
56
57         int mainline;
58         int commit_argc;
59         const char **commit_argv;
60
61         /* Merge strategy */
62         const char *strategy;
63         const char **xopts;
64         size_t xopts_nr, xopts_alloc;
65 };
66
67 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
68
69 static const char *action_name(const struct replay_opts *opts)
70 {
71         return opts->action == REVERT ? "revert" : "cherry-pick";
72 }
73
74 static char *get_encoding(const char *message);
75
76 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
77 {
78         return opts->action == REVERT ? revert_usage : cherry_pick_usage;
79 }
80
81 static int option_parse_x(const struct option *opt,
82                           const char *arg, int unset)
83 {
84         struct replay_opts **opts_ptr = opt->value;
85         struct replay_opts *opts = *opts_ptr;
86
87         if (unset)
88                 return 0;
89
90         ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
91         opts->xopts[opts->xopts_nr++] = xstrdup(arg);
92         return 0;
93 }
94
95 static void verify_opt_compatible(const char *me, const char *base_opt, ...)
96 {
97         const char *this_opt;
98         va_list ap;
99
100         va_start(ap, base_opt);
101         while ((this_opt = va_arg(ap, const char *))) {
102                 if (va_arg(ap, int))
103                         break;
104         }
105         va_end(ap);
106
107         if (this_opt)
108                 die(_("%s: %s cannot be used with %s"), me, this_opt, base_opt);
109 }
110
111 static void verify_opt_mutually_compatible(const char *me, ...)
112 {
113         const char *opt1, *opt2 = NULL;
114         va_list ap;
115
116         va_start(ap, me);
117         while ((opt1 = va_arg(ap, const char *))) {
118                 if (va_arg(ap, int))
119                         break;
120         }
121         if (opt1) {
122                 while ((opt2 = va_arg(ap, const char *))) {
123                         if (va_arg(ap, int))
124                                 break;
125                 }
126         }
127
128         if (opt1 && opt2)
129                 die(_("%s: %s cannot be used with %s"), me, opt1, opt2);
130 }
131
132 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
133 {
134         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
135         const char *me = action_name(opts);
136         int reset = 0;
137         int contin = 0;
138         struct option options[] = {
139                 OPT_BOOLEAN(0, "reset", &reset, "forget the current operation"),
140                 OPT_BOOLEAN(0, "continue", &contin, "continue the current operation"),
141                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
142                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
143                 OPT_NOOP_NOARG('r', NULL),
144                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
145                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
146                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
147                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
148                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
149                         "option for merge strategy", option_parse_x),
150                 OPT_END(),
151                 OPT_END(),
152                 OPT_END(),
153         };
154
155         if (opts->action == CHERRY_PICK) {
156                 struct option cp_extra[] = {
157                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
158                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
159                         OPT_END(),
160                 };
161                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
162                         die(_("program error"));
163         }
164
165         opts->commit_argc = parse_options(argc, argv, NULL, options, usage_str,
166                                         PARSE_OPT_KEEP_ARGV0 |
167                                         PARSE_OPT_KEEP_UNKNOWN);
168
169         /* Check for incompatible subcommands */
170         verify_opt_mutually_compatible(me,
171                                 "--reset", reset,
172                                 "--continue", contin,
173                                 NULL);
174
175         /* Set the subcommand */
176         if (reset)
177                 opts->subcommand = REPLAY_RESET;
178         else if (contin)
179                 opts->subcommand = REPLAY_CONTINUE;
180         else
181                 opts->subcommand = REPLAY_NONE;
182
183         /* Check for incompatible command line arguments */
184         if (opts->subcommand != REPLAY_NONE) {
185                 char *this_operation;
186                 if (opts->subcommand == REPLAY_RESET)
187                         this_operation = "--reset";
188                 else
189                         this_operation = "--continue";
190
191                 verify_opt_compatible(me, this_operation,
192                                 "--no-commit", opts->no_commit,
193                                 "--signoff", opts->signoff,
194                                 "--mainline", opts->mainline,
195                                 "--strategy", opts->strategy ? 1 : 0,
196                                 "--strategy-option", opts->xopts ? 1 : 0,
197                                 "-x", opts->record_origin,
198                                 "--ff", opts->allow_ff,
199                                 NULL);
200         }
201
202         else if (opts->commit_argc < 2)
203                 usage_with_options(usage_str, options);
204
205         if (opts->allow_ff)
206                 verify_opt_compatible(me, "--ff",
207                                 "--signoff", opts->signoff,
208                                 "--no-commit", opts->no_commit,
209                                 "-x", opts->record_origin,
210                                 "--edit", opts->edit,
211                                 NULL);
212         opts->commit_argv = argv;
213 }
214
215 struct commit_message {
216         char *parent_label;
217         const char *label;
218         const char *subject;
219         char *reencoded_message;
220         const char *message;
221 };
222
223 static int get_message(struct commit *commit, struct commit_message *out)
224 {
225         const char *encoding;
226         const char *abbrev, *subject;
227         int abbrev_len, subject_len;
228         char *q;
229
230         if (!commit->buffer)
231                 return -1;
232         encoding = get_encoding(commit->buffer);
233         if (!encoding)
234                 encoding = "UTF-8";
235         if (!git_commit_encoding)
236                 git_commit_encoding = "UTF-8";
237
238         out->reencoded_message = NULL;
239         out->message = commit->buffer;
240         if (strcmp(encoding, git_commit_encoding))
241                 out->reencoded_message = reencode_string(commit->buffer,
242                                         git_commit_encoding, encoding);
243         if (out->reencoded_message)
244                 out->message = out->reencoded_message;
245
246         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
247         abbrev_len = strlen(abbrev);
248
249         subject_len = find_commit_subject(out->message, &subject);
250
251         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
252                               strlen("... ") + subject_len + 1);
253         q = out->parent_label;
254         q = mempcpy(q, "parent of ", strlen("parent of "));
255         out->label = q;
256         q = mempcpy(q, abbrev, abbrev_len);
257         q = mempcpy(q, "... ", strlen("... "));
258         out->subject = q;
259         q = mempcpy(q, subject, subject_len);
260         *q = '\0';
261         return 0;
262 }
263
264 static void free_message(struct commit_message *msg)
265 {
266         free(msg->parent_label);
267         free(msg->reencoded_message);
268 }
269
270 static char *get_encoding(const char *message)
271 {
272         const char *p = message, *eol;
273
274         while (*p && *p != '\n') {
275                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
276                         ; /* do nothing */
277                 if (!prefixcmp(p, "encoding ")) {
278                         char *result = xmalloc(eol - 8 - p);
279                         strlcpy(result, p + 9, eol - 8 - p);
280                         return result;
281                 }
282                 p = eol;
283                 if (*p == '\n')
284                         p++;
285         }
286         return NULL;
287 }
288
289 static void write_cherry_pick_head(struct commit *commit)
290 {
291         int fd;
292         struct strbuf buf = STRBUF_INIT;
293
294         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
295
296         fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
297         if (fd < 0)
298                 die_errno(_("Could not open '%s' for writing"),
299                           git_path("CHERRY_PICK_HEAD"));
300         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
301                 die_errno(_("Could not write to '%s'"), git_path("CHERRY_PICK_HEAD"));
302         strbuf_release(&buf);
303 }
304
305 static void print_advice(int show_hint)
306 {
307         char *msg = getenv("GIT_CHERRY_PICK_HELP");
308
309         if (msg) {
310                 fprintf(stderr, "%s\n", msg);
311                 /*
312                  * A conflict has occured but the porcelain
313                  * (typically rebase --interactive) wants to take care
314                  * of the commit itself so remove CHERRY_PICK_HEAD
315                  */
316                 unlink(git_path("CHERRY_PICK_HEAD"));
317                 return;
318         }
319
320         if (show_hint) {
321                 advise("after resolving the conflicts, mark the corrected paths");
322                 advise("with 'git add <paths>' or 'git rm <paths>'");
323                 advise("and commit the result with 'git commit'");
324         }
325 }
326
327 static void write_message(struct strbuf *msgbuf, const char *filename)
328 {
329         static struct lock_file msg_file;
330
331         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
332                                                LOCK_DIE_ON_ERROR);
333         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
334                 die_errno(_("Could not write to %s."), filename);
335         strbuf_release(msgbuf);
336         if (commit_lock_file(&msg_file) < 0)
337                 die(_("Error wrapping up %s"), filename);
338 }
339
340 static struct tree *empty_tree(void)
341 {
342         return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
343 }
344
345 static int error_dirty_index(struct replay_opts *opts)
346 {
347         if (read_cache_unmerged())
348                 return error_resolve_conflict(action_name(opts));
349
350         /* Different translation strings for cherry-pick and revert */
351         if (opts->action == CHERRY_PICK)
352                 error(_("Your local changes would be overwritten by cherry-pick."));
353         else
354                 error(_("Your local changes would be overwritten by revert."));
355
356         if (advice_commit_before_merge)
357                 advise(_("Commit your changes or stash them to proceed."));
358         return -1;
359 }
360
361 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
362 {
363         struct ref_lock *ref_lock;
364
365         read_cache();
366         if (checkout_fast_forward(from, to))
367                 exit(1); /* the callee should have complained already */
368         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
369         return write_ref_sha1(ref_lock, to, "cherry-pick");
370 }
371
372 static int do_recursive_merge(struct commit *base, struct commit *next,
373                               const char *base_label, const char *next_label,
374                               unsigned char *head, struct strbuf *msgbuf,
375                               struct replay_opts *opts)
376 {
377         struct merge_options o;
378         struct tree *result, *next_tree, *base_tree, *head_tree;
379         int clean, index_fd;
380         const char **xopt;
381         static struct lock_file index_lock;
382
383         index_fd = hold_locked_index(&index_lock, 1);
384
385         read_cache();
386
387         init_merge_options(&o);
388         o.ancestor = base ? base_label : "(empty tree)";
389         o.branch1 = "HEAD";
390         o.branch2 = next ? next_label : "(empty tree)";
391
392         head_tree = parse_tree_indirect(head);
393         next_tree = next ? next->tree : empty_tree();
394         base_tree = base ? base->tree : empty_tree();
395
396         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
397                 parse_merge_opt(&o, *xopt);
398
399         clean = merge_trees(&o,
400                             head_tree,
401                             next_tree, base_tree, &result);
402
403         if (active_cache_changed &&
404             (write_cache(index_fd, active_cache, active_nr) ||
405              commit_locked_index(&index_lock)))
406                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
407                 die(_("%s: Unable to write new index file"), action_name(opts));
408         rollback_lock_file(&index_lock);
409
410         if (!clean) {
411                 int i;
412                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
413                 for (i = 0; i < active_nr;) {
414                         struct cache_entry *ce = active_cache[i++];
415                         if (ce_stage(ce)) {
416                                 strbuf_addch(msgbuf, '\t');
417                                 strbuf_addstr(msgbuf, ce->name);
418                                 strbuf_addch(msgbuf, '\n');
419                                 while (i < active_nr && !strcmp(ce->name,
420                                                 active_cache[i]->name))
421                                         i++;
422                         }
423                 }
424         }
425
426         return !clean;
427 }
428
429 /*
430  * If we are cherry-pick, and if the merge did not result in
431  * hand-editing, we will hit this commit and inherit the original
432  * author date and name.
433  * If we are revert, or if our cherry-pick results in a hand merge,
434  * we had better say that the current user is responsible for that.
435  */
436 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
437 {
438         /* 6 is max possible length of our args array including NULL */
439         const char *args[6];
440         int i = 0;
441
442         args[i++] = "commit";
443         args[i++] = "-n";
444         if (opts->signoff)
445                 args[i++] = "-s";
446         if (!opts->edit) {
447                 args[i++] = "-F";
448                 args[i++] = defmsg;
449         }
450         args[i] = NULL;
451
452         return run_command_v_opt(args, RUN_GIT_CMD);
453 }
454
455 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
456 {
457         unsigned char head[20];
458         struct commit *base, *next, *parent;
459         const char *base_label, *next_label;
460         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
461         char *defmsg = NULL;
462         struct strbuf msgbuf = STRBUF_INIT;
463         int res;
464
465         if (opts->no_commit) {
466                 /*
467                  * We do not intend to commit immediately.  We just want to
468                  * merge the differences in, so let's compute the tree
469                  * that represents the "current" state for merge-recursive
470                  * to work on.
471                  */
472                 if (write_cache_as_tree(head, 0, NULL))
473                         die (_("Your index file is unmerged."));
474         } else {
475                 if (get_sha1("HEAD", head))
476                         return error(_("You do not have a valid HEAD"));
477                 if (index_differs_from("HEAD", 0))
478                         return error_dirty_index(opts);
479         }
480         discard_cache();
481
482         if (!commit->parents) {
483                 parent = NULL;
484         }
485         else if (commit->parents->next) {
486                 /* Reverting or cherry-picking a merge commit */
487                 int cnt;
488                 struct commit_list *p;
489
490                 if (!opts->mainline)
491                         return error(_("Commit %s is a merge but no -m option was given."),
492                                 sha1_to_hex(commit->object.sha1));
493
494                 for (cnt = 1, p = commit->parents;
495                      cnt != opts->mainline && p;
496                      cnt++)
497                         p = p->next;
498                 if (cnt != opts->mainline || !p)
499                         return error(_("Commit %s does not have parent %d"),
500                                 sha1_to_hex(commit->object.sha1), opts->mainline);
501                 parent = p->item;
502         } else if (0 < opts->mainline)
503                 return error(_("Mainline was specified but commit %s is not a merge."),
504                         sha1_to_hex(commit->object.sha1));
505         else
506                 parent = commit->parents->item;
507
508         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
509                 return fast_forward_to(commit->object.sha1, head);
510
511         if (parent && parse_commit(parent) < 0)
512                 /* TRANSLATORS: The first %s will be "revert" or
513                    "cherry-pick", the second %s a SHA1 */
514                 return error(_("%s: cannot parse parent commit %s"),
515                         action_name(opts), sha1_to_hex(parent->object.sha1));
516
517         if (get_message(commit, &msg) != 0)
518                 return error(_("Cannot get commit message for %s"),
519                         sha1_to_hex(commit->object.sha1));
520
521         /*
522          * "commit" is an existing commit.  We would want to apply
523          * the difference it introduces since its first parent "prev"
524          * on top of the current HEAD if we are cherry-pick.  Or the
525          * reverse of it if we are revert.
526          */
527
528         defmsg = git_pathdup("MERGE_MSG");
529
530         if (opts->action == REVERT) {
531                 base = commit;
532                 base_label = msg.label;
533                 next = parent;
534                 next_label = msg.parent_label;
535                 strbuf_addstr(&msgbuf, "Revert \"");
536                 strbuf_addstr(&msgbuf, msg.subject);
537                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
538                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
539
540                 if (commit->parents && commit->parents->next) {
541                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
542                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
543                 }
544                 strbuf_addstr(&msgbuf, ".\n");
545         } else {
546                 const char *p;
547
548                 base = parent;
549                 base_label = msg.parent_label;
550                 next = commit;
551                 next_label = msg.label;
552
553                 /*
554                  * Append the commit log message to msgbuf; it starts
555                  * after the tree, parent, author, committer
556                  * information followed by "\n\n".
557                  */
558                 p = strstr(msg.message, "\n\n");
559                 if (p) {
560                         p += 2;
561                         strbuf_addstr(&msgbuf, p);
562                 }
563
564                 if (opts->record_origin) {
565                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
566                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
567                         strbuf_addstr(&msgbuf, ")\n");
568                 }
569         }
570
571         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
572                 res = do_recursive_merge(base, next, base_label, next_label,
573                                          head, &msgbuf, opts);
574                 write_message(&msgbuf, defmsg);
575         } else {
576                 struct commit_list *common = NULL;
577                 struct commit_list *remotes = NULL;
578
579                 write_message(&msgbuf, defmsg);
580
581                 commit_list_insert(base, &common);
582                 commit_list_insert(next, &remotes);
583                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
584                                         common, sha1_to_hex(head), remotes);
585                 free_commit_list(common);
586                 free_commit_list(remotes);
587         }
588
589         /*
590          * If the merge was clean or if it failed due to conflict, we write
591          * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
592          * However, if the merge did not even start, then we don't want to
593          * write it at all.
594          */
595         if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
596                 write_cherry_pick_head(commit);
597
598         if (res) {
599                 error(opts->action == REVERT
600                       ? _("could not revert %s... %s")
601                       : _("could not apply %s... %s"),
602                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
603                       msg.subject);
604                 print_advice(res == 1);
605                 rerere(opts->allow_rerere_auto);
606         } else {
607                 if (!opts->no_commit)
608                         res = run_git_commit(defmsg, opts);
609         }
610
611         free_message(&msg);
612         free(defmsg);
613
614         return res;
615 }
616
617 static void prepare_revs(struct rev_info *revs, struct replay_opts *opts)
618 {
619         int argc;
620
621         init_revisions(revs, NULL);
622         revs->no_walk = 1;
623         if (opts->action != REVERT)
624                 revs->reverse = 1;
625
626         argc = setup_revisions(opts->commit_argc, opts->commit_argv, revs, NULL);
627         if (argc > 1)
628                 usage(*revert_or_cherry_pick_usage(opts));
629
630         if (prepare_revision_walk(revs))
631                 die(_("revision walk setup failed"));
632
633         if (!revs->commits)
634                 die(_("empty commit set passed"));
635 }
636
637 static void read_and_refresh_cache(struct replay_opts *opts)
638 {
639         static struct lock_file index_lock;
640         int index_fd = hold_locked_index(&index_lock, 0);
641         if (read_index_preload(&the_index, NULL) < 0)
642                 die(_("git %s: failed to read the index"), action_name(opts));
643         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
644         if (the_index.cache_changed) {
645                 if (write_index(&the_index, index_fd) ||
646                     commit_locked_index(&index_lock))
647                         die(_("git %s: failed to refresh the index"), action_name(opts));
648         }
649         rollback_lock_file(&index_lock);
650 }
651
652 /*
653  * Append a commit to the end of the commit_list.
654  *
655  * next starts by pointing to the variable that holds the head of an
656  * empty commit_list, and is updated to point to the "next" field of
657  * the last item on the list as new commits are appended.
658  *
659  * Usage example:
660  *
661  *     struct commit_list *list;
662  *     struct commit_list **next = &list;
663  *
664  *     next = commit_list_append(c1, next);
665  *     next = commit_list_append(c2, next);
666  *     assert(commit_list_count(list) == 2);
667  *     return list;
668  */
669 static struct commit_list **commit_list_append(struct commit *commit,
670                                                struct commit_list **next)
671 {
672         struct commit_list *new = xmalloc(sizeof(struct commit_list));
673         new->item = commit;
674         *next = new;
675         new->next = NULL;
676         return &new->next;
677 }
678
679 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
680                 struct replay_opts *opts)
681 {
682         struct commit_list *cur = NULL;
683         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
684         const char *sha1_abbrev = NULL;
685         const char *action_str = opts->action == REVERT ? "revert" : "pick";
686
687         for (cur = todo_list; cur; cur = cur->next) {
688                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
689                 if (get_message(cur->item, &msg))
690                         return error(_("Cannot get commit message for %s"), sha1_abbrev);
691                 strbuf_addf(buf, "%s %s %s\n", action_str, sha1_abbrev, msg.subject);
692         }
693         return 0;
694 }
695
696 static struct commit *parse_insn_line(char *start, struct replay_opts *opts)
697 {
698         unsigned char commit_sha1[20];
699         char sha1_abbrev[40];
700         enum replay_action action;
701         int insn_len = 0;
702         char *p, *q;
703
704         if (!prefixcmp(start, "pick ")) {
705                 action = CHERRY_PICK;
706                 insn_len = strlen("pick");
707                 p = start + insn_len + 1;
708         } else if (!prefixcmp(start, "revert ")) {
709                 action = REVERT;
710                 insn_len = strlen("revert");
711                 p = start + insn_len + 1;
712         } else
713                 return NULL;
714
715         q = strchr(p, ' ');
716         if (!q)
717                 return NULL;
718         q++;
719
720         strlcpy(sha1_abbrev, p, q - p);
721
722         /*
723          * Verify that the action matches up with the one in
724          * opts; we don't support arbitrary instructions
725          */
726         if (action != opts->action) {
727                 const char *action_str;
728                 action_str = action == REVERT ? "revert" : "cherry-pick";
729                 error(_("Cannot %s during a %s"), action_str, action_name(opts));
730                 return NULL;
731         }
732
733         if (get_sha1(sha1_abbrev, commit_sha1) < 0)
734                 return NULL;
735
736         return lookup_commit_reference(commit_sha1);
737 }
738
739 static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
740                         struct replay_opts *opts)
741 {
742         struct commit_list **next = todo_list;
743         struct commit *commit;
744         char *p = buf;
745         int i;
746
747         for (i = 1; *p; i++) {
748                 commit = parse_insn_line(p, opts);
749                 if (!commit)
750                         return error(_("Could not parse line %d."), i);
751                 next = commit_list_append(commit, next);
752                 p = strchrnul(p, '\n');
753                 if (*p)
754                         p++;
755         }
756         if (!*todo_list)
757                 return error(_("No commits parsed."));
758         return 0;
759 }
760
761 static void read_populate_todo(struct commit_list **todo_list,
762                         struct replay_opts *opts)
763 {
764         const char *todo_file = git_path(SEQ_TODO_FILE);
765         struct strbuf buf = STRBUF_INIT;
766         int fd, res;
767
768         fd = open(todo_file, O_RDONLY);
769         if (fd < 0)
770                 die_errno(_("Could not open %s."), todo_file);
771         if (strbuf_read(&buf, fd, 0) < 0) {
772                 close(fd);
773                 strbuf_release(&buf);
774                 die(_("Could not read %s."), todo_file);
775         }
776         close(fd);
777
778         res = parse_insn_buffer(buf.buf, todo_list, opts);
779         strbuf_release(&buf);
780         if (res)
781                 die(_("Unusable instruction sheet: %s"), todo_file);
782 }
783
784 static int populate_opts_cb(const char *key, const char *value, void *data)
785 {
786         struct replay_opts *opts = data;
787         int error_flag = 1;
788
789         if (!value)
790                 error_flag = 0;
791         else if (!strcmp(key, "options.no-commit"))
792                 opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
793         else if (!strcmp(key, "options.edit"))
794                 opts->edit = git_config_bool_or_int(key, value, &error_flag);
795         else if (!strcmp(key, "options.signoff"))
796                 opts->signoff = git_config_bool_or_int(key, value, &error_flag);
797         else if (!strcmp(key, "options.record-origin"))
798                 opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
799         else if (!strcmp(key, "options.allow-ff"))
800                 opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
801         else if (!strcmp(key, "options.mainline"))
802                 opts->mainline = git_config_int(key, value);
803         else if (!strcmp(key, "options.strategy"))
804                 git_config_string(&opts->strategy, key, value);
805         else if (!strcmp(key, "options.strategy-option")) {
806                 ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
807                 opts->xopts[opts->xopts_nr++] = xstrdup(value);
808         } else
809                 return error(_("Invalid key: %s"), key);
810
811         if (!error_flag)
812                 return error(_("Invalid value for %s: %s"), key, value);
813
814         return 0;
815 }
816
817 static void read_populate_opts(struct replay_opts **opts_ptr)
818 {
819         const char *opts_file = git_path(SEQ_OPTS_FILE);
820
821         if (!file_exists(opts_file))
822                 return;
823         if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
824                 die(_("Malformed options sheet: %s"), opts_file);
825 }
826
827 static void walk_revs_populate_todo(struct commit_list **todo_list,
828                                 struct replay_opts *opts)
829 {
830         struct rev_info revs;
831         struct commit *commit;
832         struct commit_list **next;
833
834         prepare_revs(&revs, opts);
835
836         next = todo_list;
837         while ((commit = get_revision(&revs)))
838                 next = commit_list_append(commit, next);
839 }
840
841 static int create_seq_dir(void)
842 {
843         const char *seq_dir = git_path(SEQ_DIR);
844
845         if (file_exists(seq_dir))
846                 return error(_("%s already exists."), seq_dir);
847         else if (mkdir(seq_dir, 0777) < 0)
848                 die_errno(_("Could not create sequencer directory '%s'."), seq_dir);
849         return 0;
850 }
851
852 static void save_head(const char *head)
853 {
854         const char *head_file = git_path(SEQ_HEAD_FILE);
855         static struct lock_file head_lock;
856         struct strbuf buf = STRBUF_INIT;
857         int fd;
858
859         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
860         strbuf_addf(&buf, "%s\n", head);
861         if (write_in_full(fd, buf.buf, buf.len) < 0)
862                 die_errno(_("Could not write to %s."), head_file);
863         if (commit_lock_file(&head_lock) < 0)
864                 die(_("Error wrapping up %s."), head_file);
865 }
866
867 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
868 {
869         const char *todo_file = git_path(SEQ_TODO_FILE);
870         static struct lock_file todo_lock;
871         struct strbuf buf = STRBUF_INIT;
872         int fd;
873
874         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
875         if (format_todo(&buf, todo_list, opts) < 0)
876                 die(_("Could not format %s."), todo_file);
877         if (write_in_full(fd, buf.buf, buf.len) < 0) {
878                 strbuf_release(&buf);
879                 die_errno(_("Could not write to %s."), todo_file);
880         }
881         if (commit_lock_file(&todo_lock) < 0) {
882                 strbuf_release(&buf);
883                 die(_("Error wrapping up %s."), todo_file);
884         }
885         strbuf_release(&buf);
886 }
887
888 static void save_opts(struct replay_opts *opts)
889 {
890         const char *opts_file = git_path(SEQ_OPTS_FILE);
891
892         if (opts->no_commit)
893                 git_config_set_in_file(opts_file, "options.no-commit", "true");
894         if (opts->edit)
895                 git_config_set_in_file(opts_file, "options.edit", "true");
896         if (opts->signoff)
897                 git_config_set_in_file(opts_file, "options.signoff", "true");
898         if (opts->record_origin)
899                 git_config_set_in_file(opts_file, "options.record-origin", "true");
900         if (opts->allow_ff)
901                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
902         if (opts->mainline) {
903                 struct strbuf buf = STRBUF_INIT;
904                 strbuf_addf(&buf, "%d", opts->mainline);
905                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
906                 strbuf_release(&buf);
907         }
908         if (opts->strategy)
909                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
910         if (opts->xopts) {
911                 int i;
912                 for (i = 0; i < opts->xopts_nr; i++)
913                         git_config_set_multivar_in_file(opts_file,
914                                                         "options.strategy-option",
915                                                         opts->xopts[i], "^$", 0);
916         }
917 }
918
919 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
920 {
921         struct commit_list *cur;
922         int res;
923
924         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
925         if (opts->allow_ff)
926                 assert(!(opts->signoff || opts->no_commit ||
927                                 opts->record_origin || opts->edit));
928         read_and_refresh_cache(opts);
929
930         for (cur = todo_list; cur; cur = cur->next) {
931                 save_todo(cur, opts);
932                 res = do_pick_commit(cur->item, opts);
933                 if (res) {
934                         if (!cur->next)
935                                 /*
936                                  * An error was encountered while
937                                  * picking the last commit; the
938                                  * sequencer state is useless now --
939                                  * the user simply needs to resolve
940                                  * the conflict and commit
941                                  */
942                                 remove_sequencer_state(0);
943                         return res;
944                 }
945         }
946
947         /*
948          * Sequence of picks finished successfully; cleanup by
949          * removing the .git/sequencer directory
950          */
951         remove_sequencer_state(1);
952         return 0;
953 }
954
955 static int pick_revisions(struct replay_opts *opts)
956 {
957         struct commit_list *todo_list = NULL;
958         unsigned char sha1[20];
959
960         read_and_refresh_cache(opts);
961
962         /*
963          * Decide what to do depending on the arguments; a fresh
964          * cherry-pick should be handled differently from an existing
965          * one that is being continued
966          */
967         if (opts->subcommand == REPLAY_RESET) {
968                 remove_sequencer_state(1);
969                 return 0;
970         } else if (opts->subcommand == REPLAY_CONTINUE) {
971                 if (!file_exists(git_path(SEQ_TODO_FILE)))
972                         goto error;
973                 read_populate_opts(&opts);
974                 read_populate_todo(&todo_list, opts);
975
976                 /* Verify that the conflict has been resolved */
977                 if (!index_differs_from("HEAD", 0))
978                         todo_list = todo_list->next;
979         } else {
980                 /*
981                  * Start a new cherry-pick/ revert sequence; but
982                  * first, make sure that an existing one isn't in
983                  * progress
984                  */
985
986                 walk_revs_populate_todo(&todo_list, opts);
987                 if (create_seq_dir() < 0) {
988                         error(_("A cherry-pick or revert is in progress."));
989                         advise(_("Use --continue to continue the operation"));
990                         advise(_("or --reset to forget about it"));
991                         return -1;
992                 }
993                 if (get_sha1("HEAD", sha1)) {
994                         if (opts->action == REVERT)
995                                 return error(_("Can't revert as initial commit"));
996                         return error(_("Can't cherry-pick into empty head"));
997                 }
998                 save_head(sha1_to_hex(sha1));
999                 save_opts(opts);
1000         }
1001         return pick_commits(todo_list, opts);
1002 error:
1003         return error(_("No %s in progress"), action_name(opts));
1004 }
1005
1006 int cmd_revert(int argc, const char **argv, const char *prefix)
1007 {
1008         struct replay_opts opts;
1009         int res;
1010
1011         memset(&opts, 0, sizeof(opts));
1012         if (isatty(0))
1013                 opts.edit = 1;
1014         opts.action = REVERT;
1015         git_config(git_default_config, NULL);
1016         parse_args(argc, argv, &opts);
1017         res = pick_revisions(&opts);
1018         if (res < 0)
1019                 die(_("revert failed"));
1020         return res;
1021 }
1022
1023 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
1024 {
1025         struct replay_opts opts;
1026         int res;
1027
1028         memset(&opts, 0, sizeof(opts));
1029         opts.action = CHERRY_PICK;
1030         git_config(git_default_config, NULL);
1031         parse_args(argc, argv, &opts);
1032         res = pick_revisions(&opts);
1033         if (res < 0)
1034                 die(_("cherry-pick failed"));
1035         return res;
1036 }