receive-pack: detect aliased updates which can occur with symrefs
[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
17 /*
18  * This implements the builtins revert and cherry-pick.
19  *
20  * Copyright (c) 2007 Johannes E. Schindelin
21  *
22  * Based on git-revert.sh, which is
23  *
24  * Copyright (c) 2005 Linus Torvalds
25  * Copyright (c) 2005 Junio C Hamano
26  */
27
28 static const char * const revert_usage[] = {
29         "git revert [options] <commit-ish>",
30         NULL
31 };
32
33 static const char * const cherry_pick_usage[] = {
34         "git cherry-pick [options] <commit-ish>",
35         NULL
36 };
37
38 static int edit, no_replay, no_commit, mainline, signoff;
39 static enum { REVERT, CHERRY_PICK } action;
40 static struct commit *commit;
41 static const char *commit_name;
42 static int allow_rerere_auto;
43
44 static const char *me;
45
46 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
47
48 static void parse_args(int argc, const char **argv)
49 {
50         const char * const * usage_str =
51                 action == REVERT ?  revert_usage : cherry_pick_usage;
52         unsigned char sha1[20];
53         int noop;
54         struct option options[] = {
55                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
56                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
57                 OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
58                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
59                 OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
60                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
61                 OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
62                 OPT_END(),
63         };
64
65         if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
66                 usage_with_options(usage_str, options);
67
68         commit_name = argv[0];
69         if (get_sha1(commit_name, sha1))
70                 die ("Cannot find '%s'", commit_name);
71         commit = lookup_commit_reference(sha1);
72         if (!commit)
73                 exit(1);
74 }
75
76 static char *get_oneline(const char *message)
77 {
78         char *result;
79         const char *p = message, *abbrev, *eol;
80         int abbrev_len, oneline_len;
81
82         if (!p)
83                 die ("Could not read commit message of %s",
84                                 sha1_to_hex(commit->object.sha1));
85         while (*p && (*p != '\n' || p[1] != '\n'))
86                 p++;
87
88         if (*p) {
89                 p += 2;
90                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
91                         ; /* do nothing */
92         } else
93                 eol = p;
94         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
95         abbrev_len = strlen(abbrev);
96         oneline_len = eol - p;
97         result = xmalloc(abbrev_len + 5 + oneline_len);
98         memcpy(result, abbrev, abbrev_len);
99         memcpy(result + abbrev_len, "... ", 4);
100         memcpy(result + abbrev_len + 4, p, oneline_len);
101         result[abbrev_len + 4 + oneline_len] = '\0';
102         return result;
103 }
104
105 static char *get_encoding(const char *message)
106 {
107         const char *p = message, *eol;
108
109         if (!p)
110                 die ("Could not read commit message of %s",
111                                 sha1_to_hex(commit->object.sha1));
112         while (*p && *p != '\n') {
113                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
114                         ; /* do nothing */
115                 if (!prefixcmp(p, "encoding ")) {
116                         char *result = xmalloc(eol - 8 - p);
117                         strlcpy(result, p + 9, eol - 8 - p);
118                         return result;
119                 }
120                 p = eol;
121                 if (*p == '\n')
122                         p++;
123         }
124         return NULL;
125 }
126
127 static struct lock_file msg_file;
128 static int msg_fd;
129
130 static void add_to_msg(const char *string)
131 {
132         int len = strlen(string);
133         if (write_in_full(msg_fd, string, len) < 0)
134                 die_errno ("Could not write to MERGE_MSG");
135 }
136
137 static void add_message_to_msg(const char *message)
138 {
139         const char *p = message;
140         while (*p && (*p != '\n' || p[1] != '\n'))
141                 p++;
142
143         if (!*p)
144                 add_to_msg(sha1_to_hex(commit->object.sha1));
145
146         p += 2;
147         add_to_msg(p);
148         return;
149 }
150
151 static void set_author_ident_env(const char *message)
152 {
153         const char *p = message;
154         if (!p)
155                 die ("Could not read commit message of %s",
156                                 sha1_to_hex(commit->object.sha1));
157         while (*p && *p != '\n') {
158                 const char *eol;
159
160                 for (eol = p; *eol && *eol != '\n'; eol++)
161                         ; /* do nothing */
162                 if (!prefixcmp(p, "author ")) {
163                         char *line, *pend, *email, *timestamp;
164
165                         p += 7;
166                         line = xmemdupz(p, eol - p);
167                         email = strchr(line, '<');
168                         if (!email)
169                                 die ("Could not extract author email from %s",
170                                         sha1_to_hex(commit->object.sha1));
171                         if (email == line)
172                                 pend = line;
173                         else
174                                 for (pend = email; pend != line + 1 &&
175                                                 isspace(pend[-1]); pend--);
176                                         ; /* do nothing */
177                         *pend = '\0';
178                         email++;
179                         timestamp = strchr(email, '>');
180                         if (!timestamp)
181                                 die ("Could not extract author time from %s",
182                                         sha1_to_hex(commit->object.sha1));
183                         *timestamp = '\0';
184                         for (timestamp++; *timestamp && isspace(*timestamp);
185                                         timestamp++)
186                                 ; /* do nothing */
187                         setenv("GIT_AUTHOR_NAME", line, 1);
188                         setenv("GIT_AUTHOR_EMAIL", email, 1);
189                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
190                         free(line);
191                         return;
192                 }
193                 p = eol;
194                 if (*p == '\n')
195                         p++;
196         }
197         die ("No author information found in %s",
198                         sha1_to_hex(commit->object.sha1));
199 }
200
201 static char *help_msg(const char *name)
202 {
203         struct strbuf helpbuf = STRBUF_INIT;
204         char *msg = getenv("GIT_CHERRY_PICK_HELP");
205
206         if (msg)
207                 return msg;
208
209         strbuf_addstr(&helpbuf, "  After resolving the conflicts,\n"
210                 "mark the corrected paths with 'git add <paths>' or 'git rm <paths>'\n"
211                 "and commit the result");
212
213         if (action == CHERRY_PICK) {
214                 strbuf_addf(&helpbuf, " with: \n"
215                         "\n"
216                         "        git commit -c %s\n",
217                         name);
218         }
219         else
220                 strbuf_addch(&helpbuf, '.');
221         return strbuf_detach(&helpbuf, NULL);
222 }
223
224 static struct tree *empty_tree(void)
225 {
226         struct tree *tree = xcalloc(1, sizeof(struct tree));
227
228         tree->object.parsed = 1;
229         tree->object.type = OBJ_TREE;
230         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
231         return tree;
232 }
233
234 static NORETURN void die_dirty_index(const char *me)
235 {
236         if (read_cache_unmerged()) {
237                 die_resolve_conflict(me);
238         } else {
239                 if (advice_commit_before_merge)
240                         die("Your local changes would be overwritten by %s.\n"
241                             "Please, commit your changes or stash them to proceed.", me);
242                 else
243                         die("Your local changes would be overwritten by %s.\n", me);
244         }
245 }
246
247 static int revert_or_cherry_pick(int argc, const char **argv)
248 {
249         unsigned char head[20];
250         struct commit *base, *next, *parent;
251         int i, index_fd, clean;
252         char *oneline, *reencoded_message = NULL;
253         const char *message, *encoding;
254         char *defmsg = git_pathdup("MERGE_MSG");
255         struct merge_options o;
256         struct tree *result, *next_tree, *base_tree, *head_tree;
257         static struct lock_file index_lock;
258
259         git_config(git_default_config, NULL);
260         me = action == REVERT ? "revert" : "cherry-pick";
261         setenv(GIT_REFLOG_ACTION, me, 0);
262         parse_args(argc, argv);
263
264         /* this is copied from the shell script, but it's never triggered... */
265         if (action == REVERT && !no_replay)
266                 die("revert is incompatible with replay");
267
268         if (read_cache() < 0)
269                 die("git %s: failed to read the index", me);
270         if (no_commit) {
271                 /*
272                  * We do not intend to commit immediately.  We just want to
273                  * merge the differences in, so let's compute the tree
274                  * that represents the "current" state for merge-recursive
275                  * to work on.
276                  */
277                 if (write_cache_as_tree(head, 0, NULL))
278                         die ("Your index file is unmerged.");
279         } else {
280                 if (get_sha1("HEAD", head))
281                         die ("You do not have a valid HEAD");
282                 if (index_differs_from("HEAD", 0))
283                         die_dirty_index(me);
284         }
285         discard_cache();
286
287         index_fd = hold_locked_index(&index_lock, 1);
288
289         if (!commit->parents) {
290                 if (action == REVERT)
291                         die ("Cannot revert a root commit");
292                 parent = NULL;
293         }
294         else if (commit->parents->next) {
295                 /* Reverting or cherry-picking a merge commit */
296                 int cnt;
297                 struct commit_list *p;
298
299                 if (!mainline)
300                         die("Commit %s is a merge but no -m option was given.",
301                             sha1_to_hex(commit->object.sha1));
302
303                 for (cnt = 1, p = commit->parents;
304                      cnt != mainline && p;
305                      cnt++)
306                         p = p->next;
307                 if (cnt != mainline || !p)
308                         die("Commit %s does not have parent %d",
309                             sha1_to_hex(commit->object.sha1), mainline);
310                 parent = p->item;
311         } else if (0 < mainline)
312                 die("Mainline was specified but commit %s is not a merge.",
313                     sha1_to_hex(commit->object.sha1));
314         else
315                 parent = commit->parents->item;
316
317         if (!(message = commit->buffer))
318                 die ("Cannot get commit message for %s",
319                                 sha1_to_hex(commit->object.sha1));
320
321         if (parent && parse_commit(parent) < 0)
322                 die("%s: cannot parse parent commit %s",
323                     me, sha1_to_hex(parent->object.sha1));
324
325         /*
326          * "commit" is an existing commit.  We would want to apply
327          * the difference it introduces since its first parent "prev"
328          * on top of the current HEAD if we are cherry-pick.  Or the
329          * reverse of it if we are revert.
330          */
331
332         msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
333                                            LOCK_DIE_ON_ERROR);
334
335         encoding = get_encoding(message);
336         if (!encoding)
337                 encoding = "UTF-8";
338         if (!git_commit_encoding)
339                 git_commit_encoding = "UTF-8";
340         if ((reencoded_message = reencode_string(message,
341                                         git_commit_encoding, encoding)))
342                 message = reencoded_message;
343
344         oneline = get_oneline(message);
345
346         if (action == REVERT) {
347                 char *oneline_body = strchr(oneline, ' ');
348
349                 base = commit;
350                 next = parent;
351                 add_to_msg("Revert \"");
352                 add_to_msg(oneline_body + 1);
353                 add_to_msg("\"\n\nThis reverts commit ");
354                 add_to_msg(sha1_to_hex(commit->object.sha1));
355
356                 if (commit->parents->next) {
357                         add_to_msg(", reversing\nchanges made to ");
358                         add_to_msg(sha1_to_hex(parent->object.sha1));
359                 }
360                 add_to_msg(".\n");
361         } else {
362                 base = parent;
363                 next = commit;
364                 set_author_ident_env(message);
365                 add_message_to_msg(message);
366                 if (no_replay) {
367                         add_to_msg("(cherry picked from commit ");
368                         add_to_msg(sha1_to_hex(commit->object.sha1));
369                         add_to_msg(")\n");
370                 }
371         }
372
373         read_cache();
374         init_merge_options(&o);
375         o.branch1 = "HEAD";
376         o.branch2 = oneline;
377
378         head_tree = parse_tree_indirect(head);
379         next_tree = next ? next->tree : empty_tree();
380         base_tree = base ? base->tree : empty_tree();
381
382         clean = merge_trees(&o,
383                             head_tree,
384                             next_tree, base_tree, &result);
385
386         if (active_cache_changed &&
387             (write_cache(index_fd, active_cache, active_nr) ||
388              commit_locked_index(&index_lock)))
389                 die("%s: Unable to write new index file", me);
390         rollback_lock_file(&index_lock);
391
392         if (!clean) {
393                 add_to_msg("\nConflicts:\n\n");
394                 for (i = 0; i < active_nr;) {
395                         struct cache_entry *ce = active_cache[i++];
396                         if (ce_stage(ce)) {
397                                 add_to_msg("\t");
398                                 add_to_msg(ce->name);
399                                 add_to_msg("\n");
400                                 while (i < active_nr && !strcmp(ce->name,
401                                                 active_cache[i]->name))
402                                         i++;
403                         }
404                 }
405                 if (commit_lock_file(&msg_file) < 0)
406                         die ("Error wrapping up %s", defmsg);
407                 fprintf(stderr, "Automatic %s failed.%s\n",
408                         me, help_msg(commit_name));
409                 rerere(allow_rerere_auto);
410                 exit(1);
411         }
412         if (commit_lock_file(&msg_file) < 0)
413                 die ("Error wrapping up %s", defmsg);
414         fprintf(stderr, "Finished one %s.\n", me);
415
416         /*
417          *
418          * If we are cherry-pick, and if the merge did not result in
419          * hand-editing, we will hit this commit and inherit the original
420          * author date and name.
421          * If we are revert, or if our cherry-pick results in a hand merge,
422          * we had better say that the current user is responsible for that.
423          */
424
425         if (!no_commit) {
426                 /* 6 is max possible length of our args array including NULL */
427                 const char *args[6];
428                 int i = 0;
429                 args[i++] = "commit";
430                 args[i++] = "-n";
431                 if (signoff)
432                         args[i++] = "-s";
433                 if (!edit) {
434                         args[i++] = "-F";
435                         args[i++] = defmsg;
436                 }
437                 args[i] = NULL;
438                 return execv_git_cmd(args);
439         }
440         free(reencoded_message);
441         free(defmsg);
442
443         return 0;
444 }
445
446 int cmd_revert(int argc, const char **argv, const char *prefix)
447 {
448         if (isatty(0))
449                 edit = 1;
450         no_replay = 1;
451         action = REVERT;
452         return revert_or_cherry_pick(argc, argv);
453 }
454
455 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
456 {
457         no_replay = 0;
458         action = CHERRY_PICK;
459         return revert_or_cherry_pick(argc, argv);
460 }