summaryrefslogtreecommitdiff
path: root/builtin/revert.c
blob: dc1b702edc6b4bd95ebf41c12bf1da6fe9d6850d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
#include "cache.h"
#include "builtin.h"
#include "object.h"
#include "commit.h"
#include "tag.h"
#include "wt-status.h"
#include "run-command.h"
#include "exec_cmd.h"
#include "utf8.h"
#include "parse-options.h"
#include "cache-tree.h"
#include "diff.h"
#include "revision.h"
#include "rerere.h"
#include "merge-recursive.h"
#include "refs.h"

/*
 * This implements the builtins revert and cherry-pick.
 *
 * Copyright (c) 2007 Johannes E. Schindelin
 *
 * Based on git-revert.sh, which is
 *
 * Copyright (c) 2005 Linus Torvalds
 * Copyright (c) 2005 Junio C Hamano
 */

static const char * const revert_usage[] = {
	"git revert [options] <commit-ish>",
	NULL
};

static const char * const cherry_pick_usage[] = {
	"git cherry-pick [options] <commit-ish>",
	NULL
};

static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
static enum { REVERT, CHERRY_PICK } action;
static struct commit *commit;
static int commit_argc;
static const char **commit_argv;
static int allow_rerere_auto;

static const char *me;

/* Merge strategy. */
static const char *strategy;
static const char **xopts;
static size_t xopts_nr, xopts_alloc;

#define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"

static char *get_encoding(const char *message);

static const char * const *revert_or_cherry_pick_usage(void)
{
	return action == REVERT ? revert_usage : cherry_pick_usage;
}

static int option_parse_x(const struct option *opt,
			  const char *arg, int unset)
{
	if (unset)
		return 0;

	ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
	xopts[xopts_nr++] = xstrdup(arg);
	return 0;
}

static void parse_args(int argc, const char **argv)
{
	const char * const * usage_str = revert_or_cherry_pick_usage();
	int noop;
	struct option options[] = {
		OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
		OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
		OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
		OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
		OPT_INTEGER('m', "mainline", &mainline, "parent number"),
		OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
		OPT_STRING(0, "strategy", &strategy, "strategy", "merge strategy"),
		OPT_CALLBACK('X', "strategy-option", &xopts, "option",
			"option for merge strategy", option_parse_x),
		OPT_END(),
		OPT_END(),
		OPT_END(),
	};

	if (action == CHERRY_PICK) {
		struct option cp_extra[] = {
			OPT_BOOLEAN('x', NULL, &no_replay, "append commit name"),
			OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
			OPT_END(),
		};
		if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
			die("program error");
	}

	commit_argc = parse_options(argc, argv, NULL, options, usage_str,
				    PARSE_OPT_KEEP_ARGV0 |
				    PARSE_OPT_KEEP_UNKNOWN);
	if (commit_argc < 2)
		usage_with_options(usage_str, options);

	commit_argv = argv;
}

struct commit_message {
	char *parent_label;
	const char *label;
	const char *subject;
	char *reencoded_message;
	const char *message;
};

static int get_message(const char *raw_message, struct commit_message *out)
{
	const char *encoding;
	const char *abbrev, *subject;
	int abbrev_len, subject_len;
	char *q;

	if (!raw_message)
		return -1;
	encoding = get_encoding(raw_message);
	if (!encoding)
		encoding = "UTF-8";
	if (!git_commit_encoding)
		git_commit_encoding = "UTF-8";

	out->reencoded_message = NULL;
	out->message = raw_message;
	if (strcmp(encoding, git_commit_encoding))
		out->reencoded_message = reencode_string(raw_message,
					git_commit_encoding, encoding);
	if (out->reencoded_message)
		out->message = out->reencoded_message;

	abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
	abbrev_len = strlen(abbrev);

	subject_len = find_commit_subject(out->message, &subject);

	out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
			      strlen("... ") + subject_len + 1);
	q = out->parent_label;
	q = mempcpy(q, "parent of ", strlen("parent of "));
	out->label = q;
	q = mempcpy(q, abbrev, abbrev_len);
	q = mempcpy(q, "... ", strlen("... "));
	out->subject = q;
	q = mempcpy(q, subject, subject_len);
	*q = '\0';
	return 0;
}

static void free_message(struct commit_message *msg)
{
	free(msg->parent_label);
	free(msg->reencoded_message);
}

static char *get_encoding(const char *message)
{
	const char *p = message, *eol;

	if (!p)
		die ("Could not read commit message of %s",
				sha1_to_hex(commit->object.sha1));
	while (*p && *p != '\n') {
		for (eol = p + 1; *eol && *eol != '\n'; eol++)
			; /* do nothing */
		if (!prefixcmp(p, "encoding ")) {
			char *result = xmalloc(eol - 8 - p);
			strlcpy(result, p + 9, eol - 8 - p);
			return result;
		}
		p = eol;
		if (*p == '\n')
			p++;
	}
	return NULL;
}

static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
{
	const char *p = message;
	while (*p && (*p != '\n' || p[1] != '\n'))
		p++;

	if (!*p)
		strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));

	p += 2;
	strbuf_addstr(msgbuf, p);
}

static void set_author_ident_env(const char *message)
{
	const char *p = message;
	if (!p)
		die ("Could not read commit message of %s",
				sha1_to_hex(commit->object.sha1));
	while (*p && *p != '\n') {
		const char *eol;

		for (eol = p; *eol && *eol != '\n'; eol++)
			; /* do nothing */
		if (!prefixcmp(p, "author ")) {
			char *line, *pend, *email, *timestamp;

			p += 7;
			line = xmemdupz(p, eol - p);
			email = strchr(line, '<');
			if (!email)
				die ("Could not extract author email from %s",
					sha1_to_hex(commit->object.sha1));
			if (email == line)
				pend = line;
			else
				for (pend = email; pend != line + 1 &&
						isspace(pend[-1]); pend--);
					; /* do nothing */
			*pend = '\0';
			email++;
			timestamp = strchr(email, '>');
			if (!timestamp)
				die ("Could not extract author time from %s",
					sha1_to_hex(commit->object.sha1));
			*timestamp = '\0';
			for (timestamp++; *timestamp && isspace(*timestamp);
					timestamp++)
				; /* do nothing */
			setenv("GIT_AUTHOR_NAME", line, 1);
			setenv("GIT_AUTHOR_EMAIL", email, 1);
			setenv("GIT_AUTHOR_DATE", timestamp, 1);
			free(line);
			return;
		}
		p = eol;
		if (*p == '\n')
			p++;
	}
	die ("No author information found in %s",
			sha1_to_hex(commit->object.sha1));
}

static void advise(const char *advice, ...)
{
	va_list params;

	va_start(params, advice);
	vreportf("hint: ", advice, params);
	va_end(params);
}

static void print_advice(void)
{
	char *msg = getenv("GIT_CHERRY_PICK_HELP");

	if (msg) {
		fprintf(stderr, "%s\n", msg);
		return;
	}

	advise("after resolving the conflicts, mark the corrected paths");
	advise("with 'git add <paths>' or 'git rm <paths>'");

	if (action == CHERRY_PICK)
		advise("and commit the result with 'git commit -c %s'",
		       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
}

static void write_message(struct strbuf *msgbuf, const char *filename)
{
	static struct lock_file msg_file;

	int msg_fd = hold_lock_file_for_update(&msg_file, filename,
					       LOCK_DIE_ON_ERROR);
	if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
		die_errno("Could not write to %s.", filename);
	strbuf_release(msgbuf);
	if (commit_lock_file(&msg_file) < 0)
		die("Error wrapping up %s", filename);
}

static struct tree *empty_tree(void)
{
	struct tree *tree = xcalloc(1, sizeof(struct tree));

	tree->object.parsed = 1;
	tree->object.type = OBJ_TREE;
	pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
	return tree;
}

static NORETURN void die_dirty_index(const char *me)
{
	if (read_cache_unmerged()) {
		die_resolve_conflict(me);
	} else {
		if (advice_commit_before_merge)
			die("Your local changes would be overwritten by %s.\n"
			    "Please, commit your changes or stash them to proceed.", me);
		else
			die("Your local changes would be overwritten by %s.\n", me);
	}
}

static int fast_forward_to(const unsigned char *to, const unsigned char *from)
{
	struct ref_lock *ref_lock;

	read_cache();
	if (checkout_fast_forward(from, to))
		exit(1); /* the callee should have complained already */
	ref_lock = lock_any_ref_for_update("HEAD", from, 0);
	return write_ref_sha1(ref_lock, to, "cherry-pick");
}

static int do_recursive_merge(struct commit *base, struct commit *next,
			      const char *base_label, const char *next_label,
			      unsigned char *head, struct strbuf *msgbuf)
{
	struct merge_options o;
	struct tree *result, *next_tree, *base_tree, *head_tree;
	int clean, index_fd;
	const char **xopt;
	static struct lock_file index_lock;

	index_fd = hold_locked_index(&index_lock, 1);

	read_cache();

	init_merge_options(&o);
	o.ancestor = base ? base_label : "(empty tree)";
	o.branch1 = "HEAD";
	o.branch2 = next ? next_label : "(empty tree)";

	head_tree = parse_tree_indirect(head);
	next_tree = next ? next->tree : empty_tree();
	base_tree = base ? base->tree : empty_tree();

	for (xopt = xopts; xopt != xopts + xopts_nr; xopt++)
		parse_merge_opt(&o, *xopt);

	clean = merge_trees(&o,
			    head_tree,
			    next_tree, base_tree, &result);

	if (active_cache_changed &&
	    (write_cache(index_fd, active_cache, active_nr) ||
	     commit_locked_index(&index_lock)))
		die("%s: Unable to write new index file", me);
	rollback_lock_file(&index_lock);

	if (!clean) {
		int i;
		strbuf_addstr(msgbuf, "\nConflicts:\n\n");
		for (i = 0; i < active_nr;) {
			struct cache_entry *ce = active_cache[i++];
			if (ce_stage(ce)) {
				strbuf_addch(msgbuf, '\t');
				strbuf_addstr(msgbuf, ce->name);
				strbuf_addch(msgbuf, '\n');
				while (i < active_nr && !strcmp(ce->name,
						active_cache[i]->name))
					i++;
			}
		}
	}

	return !clean;
}

/*
 * If we are cherry-pick, and if the merge did not result in
 * hand-editing, we will hit this commit and inherit the original
 * author date and name.
 * If we are revert, or if our cherry-pick results in a hand merge,
 * we had better say that the current user is responsible for that.
 */
static int run_git_commit(const char *defmsg)
{
	/* 6 is max possible length of our args array including NULL */
	const char *args[6];
	int i = 0;

	args[i++] = "commit";
	args[i++] = "-n";
	if (signoff)
		args[i++] = "-s";
	if (!edit) {
		args[i++] = "-F";
		args[i++] = defmsg;
	}
	args[i] = NULL;

	return run_command_v_opt(args, RUN_GIT_CMD);
}

static int do_pick_commit(void)
{
	unsigned char head[20];
	struct commit *base, *next, *parent;
	const char *base_label, *next_label;
	struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
	char *defmsg = NULL;
	struct strbuf msgbuf = STRBUF_INIT;
	int res;

	if (no_commit) {
		/*
		 * We do not intend to commit immediately.  We just want to
		 * merge the differences in, so let's compute the tree
		 * that represents the "current" state for merge-recursive
		 * to work on.
		 */
		if (write_cache_as_tree(head, 0, NULL))
			die ("Your index file is unmerged.");
	} else {
		if (get_sha1("HEAD", head))
			die ("You do not have a valid HEAD");
		if (index_differs_from("HEAD", 0))
			die_dirty_index(me);
	}
	discard_cache();

	if (!commit->parents) {
		if (action == REVERT)
			die ("Cannot revert a root commit");
		parent = NULL;
	}
	else if (commit->parents->next) {
		/* Reverting or cherry-picking a merge commit */
		int cnt;
		struct commit_list *p;

		if (!mainline)
			die("Commit %s is a merge but no -m option was given.",
			    sha1_to_hex(commit->object.sha1));

		for (cnt = 1, p = commit->parents;
		     cnt != mainline && p;
		     cnt++)
			p = p->next;
		if (cnt != mainline || !p)
			die("Commit %s does not have parent %d",
			    sha1_to_hex(commit->object.sha1), mainline);
		parent = p->item;
	} else if (0 < mainline)
		die("Mainline was specified but commit %s is not a merge.",
		    sha1_to_hex(commit->object.sha1));
	else
		parent = commit->parents->item;

	if (allow_ff && parent && !hashcmp(parent->object.sha1, head))
		return fast_forward_to(commit->object.sha1, head);

	if (parent && parse_commit(parent) < 0)
		die("%s: cannot parse parent commit %s",
		    me, sha1_to_hex(parent->object.sha1));

	if (get_message(commit->buffer, &msg) != 0)
		die("Cannot get commit message for %s",
				sha1_to_hex(commit->object.sha1));

	/*
	 * "commit" is an existing commit.  We would want to apply
	 * the difference it introduces since its first parent "prev"
	 * on top of the current HEAD if we are cherry-pick.  Or the
	 * reverse of it if we are revert.
	 */

	defmsg = git_pathdup("MERGE_MSG");

	if (action == REVERT) {
		base = commit;
		base_label = msg.label;
		next = parent;
		next_label = msg.parent_label;
		strbuf_addstr(&msgbuf, "Revert \"");
		strbuf_addstr(&msgbuf, msg.subject);
		strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
		strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));

		if (commit->parents->next) {
			strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
			strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
		}
		strbuf_addstr(&msgbuf, ".\n");
	} else {
		base = parent;
		base_label = msg.parent_label;
		next = commit;
		next_label = msg.label;
		set_author_ident_env(msg.message);
		add_message_to_msg(&msgbuf, msg.message);
		if (no_replay) {
			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
			strbuf_addstr(&msgbuf, ")\n");
		}
	}

	if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
		res = do_recursive_merge(base, next, base_label, next_label,
					 head, &msgbuf);
		write_message(&msgbuf, defmsg);
	} else {
		struct commit_list *common = NULL;
		struct commit_list *remotes = NULL;

		write_message(&msgbuf, defmsg);

		commit_list_insert(base, &common);
		commit_list_insert(next, &remotes);
		res = try_merge_command(strategy, xopts_nr, xopts, common,
					sha1_to_hex(head), remotes);
		free_commit_list(common);
		free_commit_list(remotes);
	}

	if (res) {
		error("could not %s %s... %s",
		      action == REVERT ? "revert" : "apply",
		      find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
		      msg.subject);
		print_advice();
		rerere(allow_rerere_auto);
	} else {
		if (!no_commit)
			res = run_git_commit(defmsg);
	}

	free_message(&msg);
	free(defmsg);

	return res;
}

static void prepare_revs(struct rev_info *revs)
{
	int argc;

	init_revisions(revs, NULL);
	revs->no_walk = 1;
	if (action != REVERT)
		revs->reverse = 1;

	argc = setup_revisions(commit_argc, commit_argv, revs, NULL);
	if (argc > 1)
		usage(*revert_or_cherry_pick_usage());

	if (prepare_revision_walk(revs))
		die("revision walk setup failed");

	if (!revs->commits)
		die("empty commit set passed");
}

static void read_and_refresh_cache(const char *me)
{
	static struct lock_file index_lock;
	int index_fd = hold_locked_index(&index_lock, 0);
	if (read_index_preload(&the_index, NULL) < 0)
		die("git %s: failed to read the index", me);
	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
	if (the_index.cache_changed) {
		if (write_index(&the_index, index_fd) ||
		    commit_locked_index(&index_lock))
			die("git %s: failed to refresh the index", me);
	}
	rollback_lock_file(&index_lock);
}

static int revert_or_cherry_pick(int argc, const char **argv)
{
	struct rev_info revs;

	git_config(git_default_config, NULL);
	me = action == REVERT ? "revert" : "cherry-pick";
	setenv(GIT_REFLOG_ACTION, me, 0);
	parse_args(argc, argv);

	if (allow_ff) {
		if (signoff)
			die("cherry-pick --ff cannot be used with --signoff");
		if (no_commit)
			die("cherry-pick --ff cannot be used with --no-commit");
		if (no_replay)
			die("cherry-pick --ff cannot be used with -x");
		if (edit)
			die("cherry-pick --ff cannot be used with --edit");
	}

	read_and_refresh_cache(me);

	prepare_revs(&revs);

	while ((commit = get_revision(&revs))) {
		int res = do_pick_commit();
		if (res)
			return res;
	}

	return 0;
}

int cmd_revert(int argc, const char **argv, const char *prefix)
{
	if (isatty(0))
		edit = 1;
	action = REVERT;
	return revert_or_cherry_pick(argc, argv);
}

int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
{
	action = CHERRY_PICK;
	return revert_or_cherry_pick(argc, argv);
}