Merge branch 'jn/show-num-walks'
[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 "wt-status.h"
7 #include "run-command.h"
8 #include "exec_cmd.h"
9 #include "utf8.h"
10 #include "parse-options.h"
11 #include "cache-tree.h"
12 #include "diff.h"
13 #include "revision.h"
14 #include "rerere.h"
15 #include "merge-recursive.h"
16 #include "refs.h"
17
18 /*
19  * This implements the builtins revert and cherry-pick.
20  *
21  * Copyright (c) 2007 Johannes E. Schindelin
22  *
23  * Based on git-revert.sh, which is
24  *
25  * Copyright (c) 2005 Linus Torvalds
26  * Copyright (c) 2005 Junio C Hamano
27  */
28
29 static const char * const revert_usage[] = {
30         "git revert [options] <commit-ish>",
31         NULL
32 };
33
34 static const char * const cherry_pick_usage[] = {
35         "git cherry-pick [options] <commit-ish>",
36         NULL
37 };
38
39 static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
40 static enum { REVERT, CHERRY_PICK } action;
41 static struct commit *commit;
42 static int commit_argc;
43 static const char **commit_argv;
44 static int allow_rerere_auto;
45
46 static const char *me;
47 static const char *strategy;
48
49 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
50
51 static char *get_encoding(const char *message);
52
53 static void parse_args(int argc, const char **argv)
54 {
55         const char * const * usage_str =
56                 action == REVERT ?  revert_usage : cherry_pick_usage;
57         int noop;
58         struct option options[] = {
59                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
60                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
61                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
62                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
63                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
64                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
65                 OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
66                 OPT_END(),
67                 OPT_END(),
68                 OPT_END(),
69         };
70
71         if (action == CHERRY_PICK) {
72                 struct option cp_extra[] = {
73                         OPT_BOOLEAN('x', NULL, &no_replay, "append commit name"),
74                         OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
75                         OPT_END(),
76                 };
77                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
78                         die("program error");
79         }
80
81         commit_argc = parse_options(argc, argv, NULL, options, usage_str, 0);
82         if (commit_argc < 1)
83                 usage_with_options(usage_str, options);
84
85         commit_argv = argv;
86 }
87
88 struct commit_message {
89         char *parent_label;
90         const char *label;
91         const char *subject;
92         char *reencoded_message;
93         const char *message;
94 };
95
96 static int get_message(const char *raw_message, struct commit_message *out)
97 {
98         const char *encoding;
99         const char *p, *abbrev, *eol;
100         char *q;
101         int abbrev_len, oneline_len;
102
103         if (!raw_message)
104                 return -1;
105         encoding = get_encoding(raw_message);
106         if (!encoding)
107                 encoding = "UTF-8";
108         if (!git_commit_encoding)
109                 git_commit_encoding = "UTF-8";
110
111         out->reencoded_message = NULL;
112         out->message = raw_message;
113         if (strcmp(encoding, git_commit_encoding))
114                 out->reencoded_message = reencode_string(raw_message,
115                                         git_commit_encoding, encoding);
116         if (out->reencoded_message)
117                 out->message = out->reencoded_message;
118
119         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
120         abbrev_len = strlen(abbrev);
121
122         /* Find beginning and end of commit subject. */
123         p = out->message;
124         while (*p && (*p != '\n' || p[1] != '\n'))
125                 p++;
126         if (*p) {
127                 p += 2;
128                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
129                         ; /* do nothing */
130         } else
131                 eol = p;
132         oneline_len = eol - p;
133
134         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
135                               strlen("... ") + oneline_len + 1);
136         q = out->parent_label;
137         q = mempcpy(q, "parent of ", strlen("parent of "));
138         out->label = q;
139         q = mempcpy(q, abbrev, abbrev_len);
140         q = mempcpy(q, "... ", strlen("... "));
141         out->subject = q;
142         q = mempcpy(q, p, oneline_len);
143         *q = '\0';
144         return 0;
145 }
146
147 static void free_message(struct commit_message *msg)
148 {
149         free(msg->parent_label);
150         free(msg->reencoded_message);
151 }
152
153 static char *get_encoding(const char *message)
154 {
155         const char *p = message, *eol;
156
157         if (!p)
158                 die ("Could not read commit message of %s",
159                                 sha1_to_hex(commit->object.sha1));
160         while (*p && *p != '\n') {
161                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
162                         ; /* do nothing */
163                 if (!prefixcmp(p, "encoding ")) {
164                         char *result = xmalloc(eol - 8 - p);
165                         strlcpy(result, p + 9, eol - 8 - p);
166                         return result;
167                 }
168                 p = eol;
169                 if (*p == '\n')
170                         p++;
171         }
172         return NULL;
173 }
174
175 static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
176 {
177         const char *p = message;
178         while (*p && (*p != '\n' || p[1] != '\n'))
179                 p++;
180
181         if (!*p)
182                 strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
183
184         p += 2;
185         strbuf_addstr(msgbuf, p);
186 }
187
188 static void set_author_ident_env(const char *message)
189 {
190         const char *p = message;
191         if (!p)
192                 die ("Could not read commit message of %s",
193                                 sha1_to_hex(commit->object.sha1));
194         while (*p && *p != '\n') {
195                 const char *eol;
196
197                 for (eol = p; *eol && *eol != '\n'; eol++)
198                         ; /* do nothing */
199                 if (!prefixcmp(p, "author ")) {
200                         char *line, *pend, *email, *timestamp;
201
202                         p += 7;
203                         line = xmemdupz(p, eol - p);
204                         email = strchr(line, '<');
205                         if (!email)
206                                 die ("Could not extract author email from %s",
207                                         sha1_to_hex(commit->object.sha1));
208                         if (email == line)
209                                 pend = line;
210                         else
211                                 for (pend = email; pend != line + 1 &&
212                                                 isspace(pend[-1]); pend--);
213                                         ; /* do nothing */
214                         *pend = '\0';
215                         email++;
216                         timestamp = strchr(email, '>');
217                         if (!timestamp)
218                                 die ("Could not extract author time from %s",
219                                         sha1_to_hex(commit->object.sha1));
220                         *timestamp = '\0';
221                         for (timestamp++; *timestamp && isspace(*timestamp);
222                                         timestamp++)
223                                 ; /* do nothing */
224                         setenv("GIT_AUTHOR_NAME", line, 1);
225                         setenv("GIT_AUTHOR_EMAIL", email, 1);
226                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
227                         free(line);
228                         return;
229                 }
230                 p = eol;
231                 if (*p == '\n')
232                         p++;
233         }
234         die ("No author information found in %s",
235                         sha1_to_hex(commit->object.sha1));
236 }
237
238 static char *help_msg(void)
239 {
240         struct strbuf helpbuf = STRBUF_INIT;
241         char *msg = getenv("GIT_CHERRY_PICK_HELP");
242
243         if (msg)
244                 return msg;
245
246         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
247                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
248                 "and commit the result");
249
250         if (action == CHERRY_PICK) {
251                 strbuf_addf(&helpbuf, " with: \n"
252                         "\n"
253                         "        git commit -c %s\n",
254                             sha1_to_hex(commit->object.sha1));
255         }
256         else
257                 strbuf_addch(&helpbuf, '.');
258         return strbuf_detach(&helpbuf, NULL);
259 }
260
261 static void write_message(struct strbuf *msgbuf, const char *filename)
262 {
263         static struct lock_file msg_file;
264
265         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
266                                                LOCK_DIE_ON_ERROR);
267         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
268                 die_errno("Could not write to %s.", filename);
269         strbuf_release(msgbuf);
270         if (commit_lock_file(&msg_file) < 0)
271                 die("Error wrapping up %s", filename);
272 }
273
274 static struct tree *empty_tree(void)
275 {
276         struct tree *tree = xcalloc(1, sizeof(struct tree));
277
278         tree->object.parsed = 1;
279         tree->object.type = OBJ_TREE;
280         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
281         return tree;
282 }
283
284 static NORETURN void die_dirty_index(const char *me)
285 {
286         if (read_cache_unmerged()) {
287                 die_resolve_conflict(me);
288         } else {
289                 if (advice_commit_before_merge)
290                         die("Your local changes would be overwritten by %s.\n"
291                             "Please, commit your changes or stash them to proceed.", me);
292                 else
293                         die("Your local changes would be overwritten by %s.\n", me);
294         }
295 }
296
297 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
298 {
299         struct ref_lock *ref_lock;
300
301         read_cache();
302         if (checkout_fast_forward(from, to))
303                 exit(1); /* the callee should have complained already */
304         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
305         return write_ref_sha1(ref_lock, to, "cherry-pick");
306 }
307
308 static void do_recursive_merge(struct commit *base, struct commit *next,
309                                const char *base_label, const char *next_label,
310                                unsigned char *head, struct strbuf *msgbuf,
311                                char *defmsg)
312 {
313         struct merge_options o;
314         struct tree *result, *next_tree, *base_tree, *head_tree;
315         int clean, index_fd;
316         static struct lock_file index_lock;
317
318         index_fd = hold_locked_index(&index_lock, 1);
319
320         read_cache();
321         init_merge_options(&o);
322         o.ancestor = base ? base_label : "(empty tree)";
323         o.branch1 = "HEAD";
324         o.branch2 = next ? next_label : "(empty tree)";
325
326         head_tree = parse_tree_indirect(head);
327         next_tree = next ? next->tree : empty_tree();
328         base_tree = base ? base->tree : empty_tree();
329
330         clean = merge_trees(&o,
331                             head_tree,
332                             next_tree, base_tree, &result);
333
334         if (active_cache_changed &&
335             (write_cache(index_fd, active_cache, active_nr) ||
336              commit_locked_index(&index_lock)))
337                 die("%s: Unable to write new index file", me);
338         rollback_lock_file(&index_lock);
339
340         if (!clean) {
341                 int i;
342                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
343                 for (i = 0; i < active_nr;) {
344                         struct cache_entry *ce = active_cache[i++];
345                         if (ce_stage(ce)) {
346                                 strbuf_addch(msgbuf, '\t');
347                                 strbuf_addstr(msgbuf, ce->name);
348                                 strbuf_addch(msgbuf, '\n');
349                                 while (i < active_nr && !strcmp(ce->name,
350                                                 active_cache[i]->name))
351                                         i++;
352                         }
353                 }
354                 write_message(msgbuf, defmsg);
355                 fprintf(stderr, "Automatic %s failed.%s\n",
356                         me, help_msg());
357                 rerere(allow_rerere_auto);
358                 exit(1);
359         }
360         write_message(msgbuf, defmsg);
361         fprintf(stderr, "Finished one %s.\n", me);
362 }
363
364 static int do_pick_commit(void)
365 {
366         unsigned char head[20];
367         struct commit *base, *next, *parent;
368         const char *base_label, *next_label;
369         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
370         char *defmsg = NULL;
371         struct strbuf msgbuf = STRBUF_INIT;
372
373         if (no_commit) {
374                 /*
375                  * We do not intend to commit immediately.  We just want to
376                  * merge the differences in, so let's compute the tree
377                  * that represents the "current" state for merge-recursive
378                  * to work on.
379                  */
380                 if (write_cache_as_tree(head, 0, NULL))
381                         die ("Your index file is unmerged.");
382         } else {
383                 if (get_sha1("HEAD", head))
384                         die ("You do not have a valid HEAD");
385                 if (index_differs_from("HEAD", 0))
386                         die_dirty_index(me);
387         }
388         discard_cache();
389
390         if (!commit->parents) {
391                 if (action == REVERT)
392                         die ("Cannot revert a root commit");
393                 parent = NULL;
394         }
395         else if (commit->parents->next) {
396                 /* Reverting or cherry-picking a merge commit */
397                 int cnt;
398                 struct commit_list *p;
399
400                 if (!mainline)
401                         die("Commit %s is a merge but no -m option was given.",
402                             sha1_to_hex(commit->object.sha1));
403
404                 for (cnt = 1, p = commit->parents;
405                      cnt != mainline && p;
406                      cnt++)
407                         p = p->next;
408                 if (cnt != mainline || !p)
409                         die("Commit %s does not have parent %d",
410                             sha1_to_hex(commit->object.sha1), mainline);
411                 parent = p->item;
412         } else if (0 < mainline)
413                 die("Mainline was specified but commit %s is not a merge.",
414                     sha1_to_hex(commit->object.sha1));
415         else
416                 parent = commit->parents->item;
417
418         if (allow_ff && !hashcmp(parent->object.sha1, head))
419                 return fast_forward_to(commit->object.sha1, head);
420
421         if (parent && parse_commit(parent) < 0)
422                 die("%s: cannot parse parent commit %s",
423                     me, sha1_to_hex(parent->object.sha1));
424
425         if (get_message(commit->buffer, &msg) != 0)
426                 die("Cannot get commit message for %s",
427                                 sha1_to_hex(commit->object.sha1));
428
429         /*
430          * "commit" is an existing commit.  We would want to apply
431          * the difference it introduces since its first parent "prev"
432          * on top of the current HEAD if we are cherry-pick.  Or the
433          * reverse of it if we are revert.
434          */
435
436         defmsg = git_pathdup("MERGE_MSG");
437
438         if (action == REVERT) {
439                 base = commit;
440                 base_label = msg.label;
441                 next = parent;
442                 next_label = msg.parent_label;
443                 strbuf_addstr(&msgbuf, "Revert \"");
444                 strbuf_addstr(&msgbuf, msg.subject);
445                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
446                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
447
448                 if (commit->parents->next) {
449                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
450                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
451                 }
452                 strbuf_addstr(&msgbuf, ".\n");
453         } else {
454                 base = parent;
455                 base_label = msg.parent_label;
456                 next = commit;
457                 next_label = msg.label;
458                 set_author_ident_env(msg.message);
459                 add_message_to_msg(&msgbuf, msg.message);
460                 if (no_replay) {
461                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
462                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
463                         strbuf_addstr(&msgbuf, ")\n");
464                 }
465         }
466
467         if (!strategy || !strcmp(strategy, "recursive") || action == REVERT)
468                 do_recursive_merge(base, next, base_label, next_label,
469                                    head, &msgbuf, defmsg);
470         else {
471                 int res;
472                 struct commit_list *common = NULL;
473                 struct commit_list *remotes = NULL;
474                 write_message(&msgbuf, defmsg);
475                 commit_list_insert(base, &common);
476                 commit_list_insert(next, &remotes);
477                 res = try_merge_command(strategy, common,
478                                         sha1_to_hex(head), remotes);
479                 free_commit_list(common);
480                 free_commit_list(remotes);
481                 if (res) {
482                         fprintf(stderr, "Automatic %s with strategy %s failed.%s\n",
483                                 me, strategy, help_msg());
484                         rerere(allow_rerere_auto);
485                         exit(1);
486                 }
487         }
488
489         free_message(&msg);
490
491         /*
492          *
493          * If we are cherry-pick, and if the merge did not result in
494          * hand-editing, we will hit this commit and inherit the original
495          * author date and name.
496          * If we are revert, or if our cherry-pick results in a hand merge,
497          * we had better say that the current user is responsible for that.
498          */
499
500         if (!no_commit) {
501                 /* 6 is max possible length of our args array including NULL */
502                 const char *args[6];
503                 int res;
504                 int i = 0;
505
506                 args[i++] = "commit";
507                 args[i++] = "-n";
508                 if (signoff)
509                         args[i++] = "-s";
510                 if (!edit) {
511                         args[i++] = "-F";
512                         args[i++] = defmsg;
513                 }
514                 args[i] = NULL;
515                 res = run_command_v_opt(args, RUN_GIT_CMD);
516                 free(defmsg);
517
518                 return res;
519         }
520
521         free(defmsg);
522
523         return 0;
524 }
525
526 static void prepare_revs(struct rev_info *revs)
527 {
528         int argc = 0;
529         int i;
530         const char **argv = xmalloc((commit_argc + 4) * sizeof(*argv));
531
532         argv[argc++] = NULL;
533         argv[argc++] = "--no-walk";
534         if (action != REVERT)
535                 argv[argc++] = "--reverse";
536         for (i = 0; i < commit_argc; i++)
537                 argv[argc++] = commit_argv[i];
538         argv[argc++] = NULL;
539
540         init_revisions(revs, NULL);
541         setup_revisions(argc - 1, argv, revs, NULL);
542         if (prepare_revision_walk(revs))
543                 die("revision walk setup failed");
544
545         if (!revs->commits)
546                 die("empty commit set passed");
547
548         free(argv);
549 }
550
551 static int revert_or_cherry_pick(int argc, const char **argv)
552 {
553         struct rev_info revs;
554
555         git_config(git_default_config, NULL);
556         me = action == REVERT ? "revert" : "cherry-pick";
557         setenv(GIT_REFLOG_ACTION, me, 0);
558         parse_args(argc, argv);
559
560         if (allow_ff) {
561                 if (signoff)
562                         die("cherry-pick --ff cannot be used with --signoff");
563                 if (no_commit)
564                         die("cherry-pick --ff cannot be used with --no-commit");
565                 if (no_replay)
566                         die("cherry-pick --ff cannot be used with -x");
567                 if (edit)
568                         die("cherry-pick --ff cannot be used with --edit");
569         }
570
571         if (read_cache() < 0)
572                 die("git %s: failed to read the index", me);
573
574         prepare_revs(&revs);
575
576         while ((commit = get_revision(&revs))) {
577                 int res = do_pick_commit();
578                 if (res)
579                         return res;
580         }
581
582         return 0;
583 }
584
585 int cmd_revert(int argc, const char **argv, const char *prefix)
586 {
587         if (isatty(0))
588                 edit = 1;
589         action = REVERT;
590         return revert_or_cherry_pick(argc, argv);
591 }
592
593 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
594 {
595         action = CHERRY_PICK;
596         return revert_or_cherry_pick(argc, argv);
597 }