Merge branch 'pb/prepare-commit-msg'
[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
13 /*
14  * This implements the builtins revert and cherry-pick.
15  *
16  * Copyright (c) 2007 Johannes E. Schindelin
17  *
18  * Based on git-revert.sh, which is
19  *
20  * Copyright (c) 2005 Linus Torvalds
21  * Copyright (c) 2005 Junio C Hamano
22  */
23
24 static const char * const revert_usage[] = {
25         "git-revert [options] <commit-ish>",
26         NULL
27 };
28
29 static const char * const cherry_pick_usage[] = {
30         "git-cherry-pick [options] <commit-ish>",
31         NULL
32 };
33
34 static int edit, no_replay, no_commit, mainline;
35 static enum { REVERT, CHERRY_PICK } action;
36 static struct commit *commit;
37
38 static const char *me;
39
40 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
41
42 static void parse_args(int argc, const char **argv)
43 {
44         const char * const * usage_str =
45                 action == REVERT ?  revert_usage : cherry_pick_usage;
46         unsigned char sha1[20];
47         const char *arg;
48         int noop;
49         struct option options[] = {
50                 OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
51                 OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
52                 OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
53                 OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
54                 OPT_INTEGER('m', "mainline", &mainline, "parent number"),
55                 OPT_END(),
56         };
57
58         if (parse_options(argc, argv, options, usage_str, 0) != 1)
59                 usage_with_options(usage_str, options);
60         arg = argv[0];
61
62         if (get_sha1(arg, sha1))
63                 die ("Cannot find '%s'", arg);
64         commit = (struct commit *)parse_object(sha1);
65         if (!commit)
66                 die ("Could not find %s", sha1_to_hex(sha1));
67         if (commit->object.type == OBJ_TAG) {
68                 commit = (struct commit *)
69                         deref_tag((struct object *)commit, arg, strlen(arg));
70         }
71         if (commit->object.type != OBJ_COMMIT)
72                 die ("'%s' does not point to a commit", arg);
73 }
74
75 static char *get_oneline(const char *message)
76 {
77         char *result;
78         const char *p = message, *abbrev, *eol;
79         int abbrev_len, oneline_len;
80
81         if (!p)
82                 die ("Could not read commit message of %s",
83                                 sha1_to_hex(commit->object.sha1));
84         while (*p && (*p != '\n' || p[1] != '\n'))
85                 p++;
86
87         if (*p) {
88                 p += 2;
89                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
90                         ; /* do nothing */
91         } else
92                 eol = p;
93         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
94         abbrev_len = strlen(abbrev);
95         oneline_len = eol - p;
96         result = xmalloc(abbrev_len + 5 + oneline_len);
97         memcpy(result, abbrev, abbrev_len);
98         memcpy(result + abbrev_len, "... ", 4);
99         memcpy(result + abbrev_len + 4, p, oneline_len);
100         result[abbrev_len + 4 + oneline_len] = '\0';
101         return result;
102 }
103
104 static char *get_encoding(const char *message)
105 {
106         const char *p = message, *eol;
107
108         if (!p)
109                 die ("Could not read commit message of %s",
110                                 sha1_to_hex(commit->object.sha1));
111         while (*p && *p != '\n') {
112                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
113                         ; /* do nothing */
114                 if (!prefixcmp(p, "encoding ")) {
115                         char *result = xmalloc(eol - 8 - p);
116                         strlcpy(result, p + 9, eol - 8 - p);
117                         return result;
118                 }
119                 p = eol;
120                 if (*p == '\n')
121                         p++;
122         }
123         return NULL;
124 }
125
126 static struct lock_file msg_file;
127 static int msg_fd;
128
129 static void add_to_msg(const char *string)
130 {
131         int len = strlen(string);
132         if (write_in_full(msg_fd, string, len) < 0)
133                 die ("Could not write to MERGE_MSG");
134 }
135
136 static void add_message_to_msg(const char *message)
137 {
138         const char *p = message;
139         while (*p && (*p != '\n' || p[1] != '\n'))
140                 p++;
141
142         if (!*p)
143                 add_to_msg(sha1_to_hex(commit->object.sha1));
144
145         p += 2;
146         add_to_msg(p);
147         return;
148 }
149
150 static void set_author_ident_env(const char *message)
151 {
152         const char *p = message;
153         if (!p)
154                 die ("Could not read commit message of %s",
155                                 sha1_to_hex(commit->object.sha1));
156         while (*p && *p != '\n') {
157                 const char *eol;
158
159                 for (eol = p; *eol && *eol != '\n'; eol++)
160                         ; /* do nothing */
161                 if (!prefixcmp(p, "author ")) {
162                         char *line, *pend, *email, *timestamp;
163
164                         p += 7;
165                         line = xmemdupz(p, eol - p);
166                         email = strchr(line, '<');
167                         if (!email)
168                                 die ("Could not extract author email from %s",
169                                         sha1_to_hex(commit->object.sha1));
170                         if (email == line)
171                                 pend = line;
172                         else
173                                 for (pend = email; pend != line + 1 &&
174                                                 isspace(pend[-1]); pend--);
175                                         ; /* do nothing */
176                         *pend = '\0';
177                         email++;
178                         timestamp = strchr(email, '>');
179                         if (!timestamp)
180                                 die ("Could not extract author email from %s",
181                                         sha1_to_hex(commit->object.sha1));
182                         *timestamp = '\0';
183                         for (timestamp++; *timestamp && isspace(*timestamp);
184                                         timestamp++)
185                                 ; /* do nothing */
186                         setenv("GIT_AUTHOR_NAME", line, 1);
187                         setenv("GIT_AUTHOR_EMAIL", email, 1);
188                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
189                         free(line);
190                         return;
191                 }
192                 p = eol;
193                 if (*p == '\n')
194                         p++;
195         }
196         die ("No author information found in %s",
197                         sha1_to_hex(commit->object.sha1));
198 }
199
200 static int merge_recursive(const char *base_sha1,
201                 const char *head_sha1, const char *head_name,
202                 const char *next_sha1, const char *next_name)
203 {
204         char buffer[256];
205         const char *argv[6];
206
207         sprintf(buffer, "GITHEAD_%s", head_sha1);
208         setenv(buffer, head_name, 1);
209         sprintf(buffer, "GITHEAD_%s", next_sha1);
210         setenv(buffer, next_name, 1);
211
212         /*
213          * This three way merge is an interesting one.  We are at
214          * $head, and would want to apply the change between $commit
215          * and $prev on top of us (when reverting), or the change between
216          * $prev and $commit on top of us (when cherry-picking or replaying).
217          */
218         argv[0] = "merge-recursive";
219         argv[1] = base_sha1;
220         argv[2] = "--";
221         argv[3] = head_sha1;
222         argv[4] = next_sha1;
223         argv[5] = NULL;
224
225         return run_command_v_opt(argv, RUN_COMMAND_NO_STDIN | RUN_GIT_CMD);
226 }
227
228 static char *help_msg(const unsigned char *sha1)
229 {
230         static char helpbuf[1024];
231         char *msg = getenv("GIT_CHERRY_PICK_HELP");
232
233         if (msg)
234                 return msg;
235
236         strcpy(helpbuf, "  After resolving the conflicts,\n"
237                "mark the corrected paths with 'git add <paths>' "
238                "or 'git rm <paths>' and commit the result.");
239
240         if (action == CHERRY_PICK) {
241                 sprintf(helpbuf + strlen(helpbuf),
242                         "\nWhen commiting, use the option "
243                         "'-c %s' to retain authorship and message.",
244                         find_unique_abbrev(sha1, DEFAULT_ABBREV));
245         }
246         return helpbuf;
247 }
248
249 static int revert_or_cherry_pick(int argc, const char **argv)
250 {
251         unsigned char head[20];
252         struct commit *base, *next, *parent;
253         int i;
254         char *oneline, *reencoded_message = NULL;
255         const char *message, *encoding;
256         const char *defmsg = xstrdup(git_path("MERGE_MSG"));
257
258         git_config(git_default_config);
259         me = action == REVERT ? "revert" : "cherry-pick";
260         setenv(GIT_REFLOG_ACTION, me, 0);
261         parse_args(argc, argv);
262
263         /* this is copied from the shell script, but it's never triggered... */
264         if (action == REVERT && !no_replay)
265                 die("revert is incompatible with replay");
266
267         if (no_commit) {
268                 /*
269                  * We do not intend to commit immediately.  We just want to
270                  * merge the differences in, so let's compute the tree
271                  * that represents the "current" state for merge-recursive
272                  * to work on.
273                  */
274                 if (write_cache_as_tree(head, 0, NULL))
275                         die ("Your index file is unmerged.");
276         } else {
277                 struct wt_status s;
278
279                 if (get_sha1("HEAD", head))
280                         die ("You do not have a valid HEAD");
281                 wt_status_prepare(&s);
282                 if (s.commitable)
283                         die ("Dirty index: cannot %s", me);
284                 discard_cache();
285         }
286
287         if (!commit->parents)
288                 die ("Cannot %s a root commit", me);
289         if (commit->parents->next) {
290                 /* Reverting or cherry-picking a merge commit */
291                 int cnt;
292                 struct commit_list *p;
293
294                 if (!mainline)
295                         die("Commit %s is a merge but no -m option was given.",
296                             sha1_to_hex(commit->object.sha1));
297
298                 for (cnt = 1, p = commit->parents;
299                      cnt != mainline && p;
300                      cnt++)
301                         p = p->next;
302                 if (cnt != mainline || !p)
303                         die("Commit %s does not have parent %d",
304                             sha1_to_hex(commit->object.sha1), mainline);
305                 parent = p->item;
306         } else if (0 < mainline)
307                 die("Mainline was specified but commit %s is not a merge.",
308                     sha1_to_hex(commit->object.sha1));
309         else
310                 parent = commit->parents->item;
311
312         if (!(message = commit->buffer))
313                 die ("Cannot get commit message for %s",
314                                 sha1_to_hex(commit->object.sha1));
315
316         /*
317          * "commit" is an existing commit.  We would want to apply
318          * the difference it introduces since its first parent "prev"
319          * on top of the current HEAD if we are cherry-pick.  Or the
320          * reverse of it if we are revert.
321          */
322
323         msg_fd = hold_lock_file_for_update(&msg_file, defmsg, 1);
324
325         encoding = get_encoding(message);
326         if (!encoding)
327                 encoding = "utf-8";
328         if (!git_commit_encoding)
329                 git_commit_encoding = "utf-8";
330         if ((reencoded_message = reencode_string(message,
331                                         git_commit_encoding, encoding)))
332                 message = reencoded_message;
333
334         oneline = get_oneline(message);
335
336         if (action == REVERT) {
337                 char *oneline_body = strchr(oneline, ' ');
338
339                 base = commit;
340                 next = parent;
341                 add_to_msg("Revert \"");
342                 add_to_msg(oneline_body + 1);
343                 add_to_msg("\"\n\nThis reverts commit ");
344                 add_to_msg(sha1_to_hex(commit->object.sha1));
345                 add_to_msg(".\n");
346         } else {
347                 base = parent;
348                 next = commit;
349                 set_author_ident_env(message);
350                 add_message_to_msg(message);
351                 if (no_replay) {
352                         add_to_msg("(cherry picked from commit ");
353                         add_to_msg(sha1_to_hex(commit->object.sha1));
354                         add_to_msg(")\n");
355                 }
356         }
357
358         if (merge_recursive(sha1_to_hex(base->object.sha1),
359                                 sha1_to_hex(head), "HEAD",
360                                 sha1_to_hex(next->object.sha1), oneline) ||
361                         write_cache_as_tree(head, 0, NULL)) {
362                 add_to_msg("\nConflicts:\n\n");
363                 read_cache();
364                 for (i = 0; i < active_nr;) {
365                         struct cache_entry *ce = active_cache[i++];
366                         if (ce_stage(ce)) {
367                                 add_to_msg("\t");
368                                 add_to_msg(ce->name);
369                                 add_to_msg("\n");
370                                 while (i < active_nr && !strcmp(ce->name,
371                                                 active_cache[i]->name))
372                                         i++;
373                         }
374                 }
375                 if (commit_lock_file(&msg_file) < 0)
376                         die ("Error wrapping up %s", defmsg);
377                 fprintf(stderr, "Automatic %s failed.%s\n",
378                         me, help_msg(commit->object.sha1));
379                 exit(1);
380         }
381         if (commit_lock_file(&msg_file) < 0)
382                 die ("Error wrapping up %s", defmsg);
383         fprintf(stderr, "Finished one %s.\n", me);
384
385         /*
386          *
387          * If we are cherry-pick, and if the merge did not result in
388          * hand-editing, we will hit this commit and inherit the original
389          * author date and name.
390          * If we are revert, or if our cherry-pick results in a hand merge,
391          * we had better say that the current user is responsible for that.
392          */
393
394         if (!no_commit) {
395                 if (edit)
396                         return execl_git_cmd("commit", "-n", NULL);
397                 else
398                         return execl_git_cmd("commit", "-n", "-F", defmsg, NULL);
399         }
400         if (reencoded_message)
401                 free(reencoded_message);
402
403         return 0;
404 }
405
406 int cmd_revert(int argc, const char **argv, const char *prefix)
407 {
408         if (isatty(0))
409                 edit = 1;
410         no_replay = 1;
411         action = REVERT;
412         return revert_or_cherry_pick(argc, argv);
413 }
414
415 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
416 {
417         no_replay = 0;
418         action = CHERRY_PICK;
419         return revert_or_cherry_pick(argc, argv);
420 }