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