Documentation: bisect: make a comment fit better in the man page.
[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
11 /*
12  * This implements the builtins revert and cherry-pick.
13  *
14  * Copyright (c) 2007 Johannes E. Schindelin
15  *
16  * Based on git-revert.sh, which is
17  *
18  * Copyright (c) 2005 Linus Torvalds
19  * Copyright (c) 2005 Junio C Hamano
20  */
21
22 static const char *revert_usage = "git-revert [--edit | --no-edit] [-n] <commit-ish>";
23
24 static const char *cherry_pick_usage = "git-cherry-pick [--edit] [-n] [-r] [-x] <commit-ish>";
25
26 static int edit;
27 static int replay;
28 enum { REVERT, CHERRY_PICK } action;
29 static int no_commit;
30 static struct commit *commit;
31 static int needed_deref;
32
33 static const char *me;
34
35 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
36
37 static void parse_options(int argc, const char **argv)
38 {
39         const char *usage_str = action == REVERT ?
40                 revert_usage : cherry_pick_usage;
41         unsigned char sha1[20];
42         const char *arg;
43         int i;
44
45         if (argc < 2)
46                 usage(usage_str);
47
48         for (i = 1; i < argc - 1; i++) {
49                 arg = argv[i];
50                 if (!strcmp(arg, "-n") || !strcmp(arg, "--no-commit"))
51                         no_commit = 1;
52                 else if (!strcmp(arg, "-e") || !strcmp(arg, "--edit"))
53                         edit = 1;
54                 else if (!strcmp(arg, "--no-edit"))
55                         edit = 0;
56                 else if (!strcmp(arg, "-x") || !strcmp(arg, "--i-really-want-"
57                                 "to-expose-my-private-commit-object-name"))
58                         replay = 0;
59                 else if (strcmp(arg, "-r"))
60                         usage(usage_str);
61         }
62
63         arg = argv[argc - 1];
64         if (get_sha1(arg, sha1))
65                 die ("Cannot find '%s'", arg);
66         commit = (struct commit *)parse_object(sha1);
67         if (!commit)
68                 die ("Could not find %s", sha1_to_hex(sha1));
69         if (commit->object.type == OBJ_TAG) {
70                 commit = (struct commit *)
71                         deref_tag((struct object *)commit, arg, strlen(arg));
72                 needed_deref = 1;
73         }
74         if (commit->object.type != OBJ_COMMIT)
75                 die ("'%s' does not point to a commit", arg);
76 }
77
78 static char *get_oneline(const char *message)
79 {
80         char *result;
81         const char *p = message, *abbrev, *eol;
82         int abbrev_len, oneline_len;
83
84         if (!p)
85                 die ("Could not read commit message of %s",
86                                 sha1_to_hex(commit->object.sha1));
87         while (*p && (*p != '\n' || p[1] != '\n'))
88                 p++;
89
90         if (*p) {
91                 p += 2;
92                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
93                         ; /* do nothing */
94         } else
95                 eol = p;
96         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
97         abbrev_len = strlen(abbrev);
98         oneline_len = eol - p;
99         result = xmalloc(abbrev_len + 5 + oneline_len);
100         memcpy(result, abbrev, abbrev_len);
101         memcpy(result + abbrev_len, "... ", 4);
102         memcpy(result + abbrev_len + 4, p, oneline_len);
103         result[abbrev_len + 4 + oneline_len] = '\0';
104         return result;
105 }
106
107 char *get_encoding(const char *message)
108 {
109         const char *p = message, *eol;
110
111         if (!p)
112                 die ("Could not read commit message of %s",
113                                 sha1_to_hex(commit->object.sha1));
114         while (*p && *p != '\n') {
115                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
116                         ; /* do nothing */
117                 if (!prefixcmp(p, "encoding ")) {
118                         char *result = xmalloc(eol - 8 - p);
119                         strlcpy(result, p + 9, eol - 8 - p);
120                         return result;
121                 }
122                 p = eol;
123                 if (*p == '\n')
124                         p++;
125         }
126         return NULL;
127 }
128
129 struct lock_file msg_file;
130 static int msg_fd;
131
132 static void add_to_msg(const char *string)
133 {
134         int len = strlen(string);
135         if (write_in_full(msg_fd, string, len) < 0)
136                 die ("Could not write to .msg");
137 }
138
139 static void add_message_to_msg(const char *message)
140 {
141         const char *p = message;
142         while (*p && (*p != '\n' || p[1] != '\n'))
143                 p++;
144
145         if (!*p)
146                 add_to_msg(sha1_to_hex(commit->object.sha1));
147
148         p += 2;
149         add_to_msg(p);
150         return;
151 }
152
153 static void set_author_ident_env(const char *message)
154 {
155         const char *p = message;
156         if (!p)
157                 die ("Could not read commit message of %s",
158                                 sha1_to_hex(commit->object.sha1));
159         while (*p && *p != '\n') {
160                 const char *eol;
161
162                 for (eol = p; *eol && *eol != '\n'; eol++)
163                         ; /* do nothing */
164                 if (!prefixcmp(p, "author ")) {
165                         char *line, *pend, *email, *timestamp;
166
167                         p += 7;
168                         line = xmalloc(eol + 1 - p);
169                         memcpy(line, p, eol - p);
170                         line[eol - p] = '\0';
171                         email = strchr(line, '<');
172                         if (!email)
173                                 die ("Could not extract author email from %s",
174                                         sha1_to_hex(commit->object.sha1));
175                         if (email == line)
176                                 pend = line;
177                         else
178                                 for (pend = email; pend != line + 1 &&
179                                                 isspace(pend[-1]); pend--);
180                                         ; /* do nothing */
181                         *pend = '\0';
182                         email++;
183                         timestamp = strchr(email, '>');
184                         if (!timestamp)
185                                 die ("Could not extract author email from %s",
186                                         sha1_to_hex(commit->object.sha1));
187                         *timestamp = '\0';
188                         for (timestamp++; *timestamp && isspace(*timestamp);
189                                         timestamp++)
190                                 ; /* do nothing */
191                         setenv("GIT_AUTHOR_NAME", line, 1);
192                         setenv("GIT_AUTHOR_EMAIL", email, 1);
193                         setenv("GIT_AUTHOR_DATE", timestamp, 1);
194                         free(line);
195                         return;
196                 }
197                 p = eol;
198                 if (*p == '\n')
199                         p++;
200         }
201         die ("No author information found in %s",
202                         sha1_to_hex(commit->object.sha1));
203 }
204
205 static int merge_recursive(const char *base_sha1,
206                 const char *head_sha1, const char *head_name,
207                 const char *next_sha1, const char *next_name)
208 {
209         char buffer[256];
210         const char *argv[6];
211
212         sprintf(buffer, "GITHEAD_%s", head_sha1);
213         setenv(buffer, head_name, 1);
214         sprintf(buffer, "GITHEAD_%s", next_sha1);
215         setenv(buffer, next_name, 1);
216
217         /*
218          * This three way merge is an interesting one.  We are at
219          * $head, and would want to apply the change between $commit
220          * and $prev on top of us (when reverting), or the change between
221          * $prev and $commit on top of us (when cherry-picking or replaying).
222          */
223         argv[0] = "merge-recursive";
224         argv[1] = base_sha1;
225         argv[2] = "--";
226         argv[3] = head_sha1;
227         argv[4] = next_sha1;
228         argv[5] = NULL;
229
230         return run_command_v_opt(argv, RUN_COMMAND_NO_STDIN | RUN_GIT_CMD);
231 }
232
233 static int revert_or_cherry_pick(int argc, const char **argv)
234 {
235         unsigned char head[20];
236         struct commit *base, *next;
237         int i;
238         char *oneline, *reencoded_message = NULL;
239         const char *message, *encoding;
240
241         git_config(git_default_config);
242         me = action == REVERT ? "revert" : "cherry-pick";
243         setenv(GIT_REFLOG_ACTION, me, 0);
244         parse_options(argc, argv);
245
246         /* this is copied from the shell script, but it's never triggered... */
247         if (action == REVERT && replay)
248                 die("revert is incompatible with replay");
249
250         if (no_commit) {
251                 /*
252                  * We do not intend to commit immediately.  We just want to
253                  * merge the differences in.
254                  */
255                 if (write_tree(head, 0, NULL))
256                         die ("Your index file is unmerged.");
257         } else {
258                 struct wt_status s;
259
260                 if (get_sha1("HEAD", head))
261                         die ("You do not have a valid HEAD");
262                 wt_status_prepare(&s);
263                 if (s.commitable || s.workdir_dirty)
264                         die ("Dirty index: cannot %s", me);
265                 discard_cache();
266         }
267
268         if (!commit->parents)
269                 die ("Cannot %s a root commit", me);
270         if (commit->parents->next)
271                 die ("Cannot %s a multi-parent commit.", me);
272         if (!(message = commit->buffer))
273                 die ("Cannot get commit message for %s",
274                                 sha1_to_hex(commit->object.sha1));
275
276         /*
277          * "commit" is an existing commit.  We would want to apply
278          * the difference it introduces since its first parent "prev"
279          * on top of the current HEAD if we are cherry-pick.  Or the
280          * reverse of it if we are revert.
281          */
282
283         msg_fd = hold_lock_file_for_update(&msg_file, ".msg", 1);
284
285         encoding = get_encoding(message);
286         if (!encoding)
287                 encoding = "utf-8";
288         if (!git_commit_encoding)
289                 git_commit_encoding = "utf-8";
290         if ((reencoded_message = reencode_string(message,
291                                         git_commit_encoding, encoding)))
292                 message = reencoded_message;
293
294         oneline = get_oneline(message);
295
296         if (action == REVERT) {
297                 base = commit;
298                 next = commit->parents->item;
299                 add_to_msg("Revert ");
300                 add_to_msg(find_unique_abbrev(commit->object.sha1,
301                                         DEFAULT_ABBREV));
302                 add_to_msg(oneline);
303                 add_to_msg("\nThis reverts commit ");
304                 add_to_msg(sha1_to_hex(commit->object.sha1));
305                 add_to_msg(".\n");
306         } else {
307                 base = commit->parents->item;
308                 next = commit;
309                 set_author_ident_env(message);
310                 add_message_to_msg(message);
311                 if (!replay) {
312                         add_to_msg("(cherry picked from commit ");
313                         add_to_msg(sha1_to_hex(commit->object.sha1));
314                         add_to_msg(")\n");
315                 }
316         }
317         if (needed_deref) {
318                 add_to_msg("(original 'git ");
319                 add_to_msg(me);
320                 add_to_msg("' arguments: ");
321                 for (i = 0; i < argc; i++) {
322                         if (i)
323                                 add_to_msg(" ");
324                         add_to_msg(argv[i]);
325                 }
326                 add_to_msg(")\n");
327         }
328
329         if (merge_recursive(sha1_to_hex(base->object.sha1),
330                                 sha1_to_hex(head), "HEAD",
331                                 sha1_to_hex(next->object.sha1), oneline) ||
332                         write_tree(head, 0, NULL)) {
333                 const char *target = git_path("MERGE_MSG");
334                 add_to_msg("\nConflicts:\n\n");
335                 read_cache();
336                 for (i = 0; i < active_nr;) {
337                         struct cache_entry *ce = active_cache[i++];
338                         if (ce_stage(ce)) {
339                                 add_to_msg("\t");
340                                 add_to_msg(ce->name);
341                                 add_to_msg("\n");
342                                 while (i < active_nr && !strcmp(ce->name,
343                                                 active_cache[i]->name))
344                                         i++;
345                         }
346                 }
347                 if (close(msg_fd) || commit_lock_file(&msg_file) < 0)
348                         die ("Error wrapping up .msg");
349                 unlink(target);
350                 if (rename(".msg", target))
351                         die ("Could not move .msg to %s", target);
352                 fprintf(stderr, "Automatic %s failed.  "
353                         "After resolving the conflicts,\n"
354                         "mark the corrected paths with 'git-add <paths>'\n"
355                         "and commit the result.\n", me);
356                 if (action == CHERRY_PICK) {
357                         fprintf(stderr, "When commiting, use the option "
358                                 "'-c %s' to retain authorship and message.\n",
359                                 find_unique_abbrev(commit->object.sha1,
360                                         DEFAULT_ABBREV));
361                 }
362                 exit(1);
363         }
364         if (close(msg_fd) || commit_lock_file(&msg_file) < 0)
365                 die ("Error wrapping up .msg");
366         fprintf(stderr, "Finished one %s.\n", me);
367
368         /*
369          *
370          * If we are cherry-pick, and if the merge did not result in
371          * hand-editing, we will hit this commit and inherit the original
372          * author date and name.
373          * If we are revert, or if our cherry-pick results in a hand merge,
374          * we had better say that the current user is responsible for that.
375          */
376
377         if (!no_commit) {
378                 if (edit)
379                         return execl_git_cmd("commit", "-n", "-F", ".msg",
380                                 "-e", NULL);
381                 else
382                         return execl_git_cmd("commit", "-n", "-F", ".msg",
383                                 NULL);
384         }
385         if (reencoded_message)
386                 free(reencoded_message);
387
388         return 0;
389 }
390
391 int cmd_revert(int argc, const char **argv, const char *prefix)
392 {
393         if (isatty(0))
394                 edit = 1;
395         action = REVERT;
396         return revert_or_cherry_pick(argc, argv);
397 }
398
399 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
400 {
401         replay = 1;
402         action = CHERRY_PICK;
403         return revert_or_cherry_pick(argc, argv);
404 }