Merge commit 'v1.7.0' into jc/checkout-reflog-fix
[git/git.git] / builtin-checkout.c
1 #include "cache.h"
2 #include "builtin.h"
3 #include "parse-options.h"
4 #include "refs.h"
5 #include "commit.h"
6 #include "tree.h"
7 #include "tree-walk.h"
8 #include "cache-tree.h"
9 #include "unpack-trees.h"
10 #include "dir.h"
11 #include "run-command.h"
12 #include "merge-recursive.h"
13 #include "branch.h"
14 #include "diff.h"
15 #include "revision.h"
16 #include "remote.h"
17 #include "blob.h"
18 #include "xdiff-interface.h"
19 #include "ll-merge.h"
20 #include "resolve-undo.h"
21
22 static const char * const checkout_usage[] = {
23 "git checkout [options] <branch>",
24 "git checkout [options] [<branch>] -- <file>...",
25 NULL,
26 };
27
28 struct checkout_opts {
29 int quiet;
30 int merge;
31 int force;
32 int writeout_stage;
33 int writeout_error;
34
35 const char *new_branch;
36 int new_branch_log;
37 enum branch_track track;
38 };
39
40 static int post_checkout_hook(struct commit *old, struct commit *new,
41 int changed)
42 {
43 return run_hook(NULL, "post-checkout",
44 sha1_to_hex(old ? old->object.sha1 : null_sha1),
45 sha1_to_hex(new ? new->object.sha1 : null_sha1),
46 changed ? "1" : "0", NULL);
47 /* "new" can be NULL when checking out from the index before
48 a commit exists. */
49
50 }
51
52 static int update_some(const unsigned char *sha1, const char *base, int baselen,
53 const char *pathname, unsigned mode, int stage, void *context)
54 {
55 int len;
56 struct cache_entry *ce;
57
58 if (S_ISDIR(mode))
59 return READ_TREE_RECURSIVE;
60
61 len = baselen + strlen(pathname);
62 ce = xcalloc(1, cache_entry_size(len));
63 hashcpy(ce->sha1, sha1);
64 memcpy(ce->name, base, baselen);
65 memcpy(ce->name + baselen, pathname, len - baselen);
66 ce->ce_flags = create_ce_flags(len, 0);
67 ce->ce_mode = create_ce_mode(mode);
68 add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
69 return 0;
70 }
71
72 static int read_tree_some(struct tree *tree, const char **pathspec)
73 {
74 read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
75
76 /* update the index with the given tree's info
77 * for all args, expanding wildcards, and exit
78 * with any non-zero return code.
79 */
80 return 0;
81 }
82
83 static int skip_same_name(struct cache_entry *ce, int pos)
84 {
85 while (++pos < active_nr &&
86 !strcmp(active_cache[pos]->name, ce->name))
87 ; /* skip */
88 return pos;
89 }
90
91 static int check_stage(int stage, struct cache_entry *ce, int pos)
92 {
93 while (pos < active_nr &&
94 !strcmp(active_cache[pos]->name, ce->name)) {
95 if (ce_stage(active_cache[pos]) == stage)
96 return 0;
97 pos++;
98 }
99 return error("path '%s' does not have %s version",
100 ce->name,
101 (stage == 2) ? "our" : "their");
102 }
103
104 static int check_all_stages(struct cache_entry *ce, int pos)
105 {
106 if (ce_stage(ce) != 1 ||
107 active_nr <= pos + 2 ||
108 strcmp(active_cache[pos+1]->name, ce->name) ||
109 ce_stage(active_cache[pos+1]) != 2 ||
110 strcmp(active_cache[pos+2]->name, ce->name) ||
111 ce_stage(active_cache[pos+2]) != 3)
112 return error("path '%s' does not have all three versions",
113 ce->name);
114 return 0;
115 }
116
117 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
118 struct checkout *state)
119 {
120 while (pos < active_nr &&
121 !strcmp(active_cache[pos]->name, ce->name)) {
122 if (ce_stage(active_cache[pos]) == stage)
123 return checkout_entry(active_cache[pos], state, NULL);
124 pos++;
125 }
126 return error("path '%s' does not have %s version",
127 ce->name,
128 (stage == 2) ? "our" : "their");
129 }
130
131 /* NEEDSWORK: share with merge-recursive */
132 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
133 {
134 unsigned long size;
135 enum object_type type;
136
137 if (!hashcmp(sha1, null_sha1)) {
138 mm->ptr = xstrdup("");
139 mm->size = 0;
140 return;
141 }
142
143 mm->ptr = read_sha1_file(sha1, &type, &size);
144 if (!mm->ptr || type != OBJ_BLOB)
145 die("unable to read blob object %s", sha1_to_hex(sha1));
146 mm->size = size;
147 }
148
149 static int checkout_merged(int pos, struct checkout *state)
150 {
151 struct cache_entry *ce = active_cache[pos];
152 const char *path = ce->name;
153 mmfile_t ancestor, ours, theirs;
154 int status;
155 unsigned char sha1[20];
156 mmbuffer_t result_buf;
157
158 if (ce_stage(ce) != 1 ||
159 active_nr <= pos + 2 ||
160 strcmp(active_cache[pos+1]->name, path) ||
161 ce_stage(active_cache[pos+1]) != 2 ||
162 strcmp(active_cache[pos+2]->name, path) ||
163 ce_stage(active_cache[pos+2]) != 3)
164 return error("path '%s' does not have all 3 versions", path);
165
166 fill_mm(active_cache[pos]->sha1, &ancestor);
167 fill_mm(active_cache[pos+1]->sha1, &ours);
168 fill_mm(active_cache[pos+2]->sha1, &theirs);
169
170 status = ll_merge(&result_buf, path, &ancestor,
171 &ours, "ours", &theirs, "theirs", 0);
172 free(ancestor.ptr);
173 free(ours.ptr);
174 free(theirs.ptr);
175 if (status < 0 || !result_buf.ptr) {
176 free(result_buf.ptr);
177 return error("path '%s': cannot merge", path);
178 }
179
180 /*
181 * NEEDSWORK:
182 * There is absolutely no reason to write this as a blob object
183 * and create a phony cache entry just to leak. This hack is
184 * primarily to get to the write_entry() machinery that massages
185 * the contents to work-tree format and writes out which only
186 * allows it for a cache entry. The code in write_entry() needs
187 * to be refactored to allow us to feed a <buffer, size, mode>
188 * instead of a cache entry. Such a refactoring would help
189 * merge_recursive as well (it also writes the merge result to the
190 * object database even when it may contain conflicts).
191 */
192 if (write_sha1_file(result_buf.ptr, result_buf.size,
193 blob_type, sha1))
194 die("Unable to add merge result for '%s'", path);
195 ce = make_cache_entry(create_ce_mode(active_cache[pos+1]->ce_mode),
196 sha1,
197 path, 2, 0);
198 if (!ce)
199 die("make_cache_entry failed for path '%s'", path);
200 status = checkout_entry(ce, state, NULL);
201 return status;
202 }
203
204 static int checkout_paths(struct tree *source_tree, const char **pathspec,
205 struct checkout_opts *opts)
206 {
207 int pos;
208 struct checkout state;
209 static char *ps_matched;
210 unsigned char rev[20];
211 int flag;
212 struct commit *head;
213 int errs = 0;
214 int stage = opts->writeout_stage;
215 int merge = opts->merge;
216 int newfd;
217 struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
218
219 newfd = hold_locked_index(lock_file, 1);
220 if (read_cache_preload(pathspec) < 0)
221 return error("corrupt index file");
222
223 if (source_tree)
224 read_tree_some(source_tree, pathspec);
225
226 for (pos = 0; pathspec[pos]; pos++)
227 ;
228 ps_matched = xcalloc(1, pos);
229
230 for (pos = 0; pos < active_nr; pos++) {
231 struct cache_entry *ce = active_cache[pos];
232 match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
233 }
234
235 if (report_path_error(ps_matched, pathspec, 0))
236 return 1;
237
238 /* "checkout -m path" to recreate conflicted state */
239 if (opts->merge)
240 unmerge_cache(pathspec);
241
242 /* Any unmerged paths? */
243 for (pos = 0; pos < active_nr; pos++) {
244 struct cache_entry *ce = active_cache[pos];
245 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
246 if (!ce_stage(ce))
247 continue;
248 if (opts->force) {
249 warning("path '%s' is unmerged", ce->name);
250 } else if (stage) {
251 errs |= check_stage(stage, ce, pos);
252 } else if (opts->merge) {
253 errs |= check_all_stages(ce, pos);
254 } else {
255 errs = 1;
256 error("path '%s' is unmerged", ce->name);
257 }
258 pos = skip_same_name(ce, pos) - 1;
259 }
260 }
261 if (errs)
262 return 1;
263
264 /* Now we are committed to check them out */
265 memset(&state, 0, sizeof(state));
266 state.force = 1;
267 state.refresh_cache = 1;
268 for (pos = 0; pos < active_nr; pos++) {
269 struct cache_entry *ce = active_cache[pos];
270 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
271 if (!ce_stage(ce)) {
272 errs |= checkout_entry(ce, &state, NULL);
273 continue;
274 }
275 if (stage)
276 errs |= checkout_stage(stage, ce, pos, &state);
277 else if (merge)
278 errs |= checkout_merged(pos, &state);
279 pos = skip_same_name(ce, pos) - 1;
280 }
281 }
282
283 if (write_cache(newfd, active_cache, active_nr) ||
284 commit_locked_index(lock_file))
285 die("unable to write new index file");
286
287 resolve_ref("HEAD", rev, 0, &flag);
288 head = lookup_commit_reference_gently(rev, 1);
289
290 errs |= post_checkout_hook(head, head, 0);
291 return errs;
292 }
293
294 static void show_local_changes(struct object *head)
295 {
296 struct rev_info rev;
297 /* I think we want full paths, even if we're in a subdirectory. */
298 init_revisions(&rev, NULL);
299 rev.abbrev = 0;
300 rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
301 if (diff_setup_done(&rev.diffopt) < 0)
302 die("diff_setup_done failed");
303 add_pending_object(&rev, head, NULL);
304 run_diff_index(&rev, 0);
305 }
306
307 static void describe_detached_head(char *msg, struct commit *commit)
308 {
309 struct strbuf sb = STRBUF_INIT;
310 struct pretty_print_context ctx = {0};
311 parse_commit(commit);
312 pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, &ctx);
313 fprintf(stderr, "%s %s... %s\n", msg,
314 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
315 strbuf_release(&sb);
316 }
317
318 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
319 {
320 struct unpack_trees_options opts;
321 struct tree_desc tree_desc;
322
323 memset(&opts, 0, sizeof(opts));
324 opts.head_idx = -1;
325 opts.update = worktree;
326 opts.skip_unmerged = !worktree;
327 opts.reset = 1;
328 opts.merge = 1;
329 opts.fn = oneway_merge;
330 opts.verbose_update = !o->quiet;
331 opts.src_index = &the_index;
332 opts.dst_index = &the_index;
333 parse_tree(tree);
334 init_tree_desc(&tree_desc, tree->buffer, tree->size);
335 switch (unpack_trees(1, &tree_desc, &opts)) {
336 case -2:
337 o->writeout_error = 1;
338 /*
339 * We return 0 nevertheless, as the index is all right
340 * and more importantly we have made best efforts to
341 * update paths in the work tree, and we cannot revert
342 * them.
343 */
344 case 0:
345 return 0;
346 default:
347 return 128;
348 }
349 }
350
351 struct branch_info {
352 const char *name; /* The short name used */
353 const char *path; /* The full name of a real branch */
354 struct commit *commit; /* The named commit */
355 };
356
357 static void setup_branch_path(struct branch_info *branch)
358 {
359 struct strbuf buf = STRBUF_INIT;
360
361 strbuf_branchname(&buf, branch->name);
362 if (strcmp(buf.buf, branch->name))
363 branch->name = xstrdup(buf.buf);
364 strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
365 branch->path = strbuf_detach(&buf, NULL);
366 }
367
368 static int merge_working_tree(struct checkout_opts *opts,
369 struct branch_info *old, struct branch_info *new)
370 {
371 int ret;
372 struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
373 int newfd = hold_locked_index(lock_file, 1);
374
375 if (read_cache_preload(NULL) < 0)
376 return error("corrupt index file");
377
378 resolve_undo_clear();
379 if (opts->force) {
380 ret = reset_tree(new->commit->tree, opts, 1);
381 if (ret)
382 return ret;
383 } else {
384 struct tree_desc trees[2];
385 struct tree *tree;
386 struct unpack_trees_options topts;
387
388 memset(&topts, 0, sizeof(topts));
389 topts.head_idx = -1;
390 topts.src_index = &the_index;
391 topts.dst_index = &the_index;
392
393 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
394
395 refresh_cache(REFRESH_QUIET);
396
397 if (unmerged_cache()) {
398 error("you need to resolve your current index first");
399 return 1;
400 }
401
402 /* 2-way merge to the new branch */
403 topts.initial_checkout = is_cache_unborn();
404 topts.update = 1;
405 topts.merge = 1;
406 topts.gently = opts->merge && old->commit;
407 topts.verbose_update = !opts->quiet;
408 topts.fn = twoway_merge;
409 topts.dir = xcalloc(1, sizeof(*topts.dir));
410 topts.dir->flags |= DIR_SHOW_IGNORED;
411 topts.dir->exclude_per_dir = ".gitignore";
412 tree = parse_tree_indirect(old->commit ?
413 old->commit->object.sha1 :
414 (unsigned char *)EMPTY_TREE_SHA1_BIN);
415 init_tree_desc(&trees[0], tree->buffer, tree->size);
416 tree = parse_tree_indirect(new->commit->object.sha1);
417 init_tree_desc(&trees[1], tree->buffer, tree->size);
418
419 ret = unpack_trees(2, trees, &topts);
420 if (ret == -1) {
421 /*
422 * Unpack couldn't do a trivial merge; either
423 * give up or do a real merge, depending on
424 * whether the merge flag was used.
425 */
426 struct tree *result;
427 struct tree *work;
428 struct merge_options o;
429 if (!opts->merge)
430 return 1;
431
432 /*
433 * Without old->commit, the below is the same as
434 * the two-tree unpack we already tried and failed.
435 */
436 if (!old->commit)
437 return 1;
438
439 /* Do more real merge */
440
441 /*
442 * We update the index fully, then write the
443 * tree from the index, then merge the new
444 * branch with the current tree, with the old
445 * branch as the base. Then we reset the index
446 * (but not the working tree) to the new
447 * branch, leaving the working tree as the
448 * merged version, but skipping unmerged
449 * entries in the index.
450 */
451
452 add_files_to_cache(NULL, NULL, 0);
453 init_merge_options(&o);
454 o.verbosity = 0;
455 work = write_tree_from_memory(&o);
456
457 ret = reset_tree(new->commit->tree, opts, 1);
458 if (ret)
459 return ret;
460 o.branch1 = new->name;
461 o.branch2 = "local";
462 merge_trees(&o, new->commit->tree, work,
463 old->commit->tree, &result);
464 ret = reset_tree(new->commit->tree, opts, 0);
465 if (ret)
466 return ret;
467 }
468 }
469
470 if (write_cache(newfd, active_cache, active_nr) ||
471 commit_locked_index(lock_file))
472 die("unable to write new index file");
473
474 if (!opts->force && !opts->quiet)
475 show_local_changes(&new->commit->object);
476
477 return 0;
478 }
479
480 static void report_tracking(struct branch_info *new)
481 {
482 struct strbuf sb = STRBUF_INIT;
483 struct branch *branch = branch_get(new->name);
484
485 if (!format_tracking_info(branch, &sb))
486 return;
487 fputs(sb.buf, stdout);
488 strbuf_release(&sb);
489 }
490
491 static void update_refs_for_switch(struct checkout_opts *opts,
492 struct branch_info *old,
493 struct branch_info *new)
494 {
495 struct strbuf msg = STRBUF_INIT;
496 const char *old_desc;
497 if (opts->new_branch) {
498 create_branch(old->name, opts->new_branch, new->name, 0,
499 opts->new_branch_log, opts->track);
500 new->name = opts->new_branch;
501 setup_branch_path(new);
502 }
503
504 old_desc = old->name;
505 if (!old_desc && old->commit)
506 old_desc = sha1_to_hex(old->commit->object.sha1);
507 strbuf_addf(&msg, "checkout: moving from %s to %s",
508 old_desc ? old_desc : "(invalid)", new->name);
509
510 if (new->path) {
511 create_symref("HEAD", new->path, msg.buf);
512 if (!opts->quiet) {
513 if (old->path && !strcmp(new->path, old->path))
514 fprintf(stderr, "Already on '%s'\n",
515 new->name);
516 else
517 fprintf(stderr, "Switched to%s branch '%s'\n",
518 opts->new_branch ? " a new" : "",
519 new->name);
520 }
521 } else if (strcmp(new->name, "HEAD")) {
522 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
523 REF_NODEREF, DIE_ON_ERR);
524 if (!opts->quiet) {
525 if (old->path)
526 fprintf(stderr, "Note: moving to '%s' which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n git checkout -b <new_branch_name>\n", new->name);
527 describe_detached_head("HEAD is now at", new->commit);
528 }
529 }
530 remove_branch_state();
531 strbuf_release(&msg);
532 if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
533 report_tracking(new);
534 }
535
536 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
537 {
538 int ret = 0;
539 struct branch_info old;
540 unsigned char rev[20];
541 int flag;
542 memset(&old, 0, sizeof(old));
543 old.path = xstrdup(resolve_ref("HEAD", rev, 0, &flag));
544 old.commit = lookup_commit_reference_gently(rev, 1);
545 if (!(flag & REF_ISSYMREF)) {
546 free((char *)old.path);
547 old.path = NULL;
548 }
549
550 if (old.path && !prefixcmp(old.path, "refs/heads/"))
551 old.name = old.path + strlen("refs/heads/");
552
553 if (!new->name) {
554 new->name = "HEAD";
555 new->commit = old.commit;
556 if (!new->commit)
557 die("You are on a branch yet to be born");
558 parse_commit(new->commit);
559 }
560
561 ret = merge_working_tree(opts, &old, new);
562 if (ret)
563 return ret;
564
565 /*
566 * If we were on a detached HEAD, but have now moved to
567 * a new commit, we want to mention the old commit once more
568 * to remind the user that it might be lost.
569 */
570 if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
571 describe_detached_head("Previous HEAD position was", old.commit);
572
573 update_refs_for_switch(opts, &old, new);
574
575 ret = post_checkout_hook(old.commit, new->commit, 1);
576 free((char *)old.path);
577 return ret || opts->writeout_error;
578 }
579
580 static int git_checkout_config(const char *var, const char *value, void *cb)
581 {
582 return git_xmerge_config(var, value, cb);
583 }
584
585 static int interactive_checkout(const char *revision, const char **pathspec,
586 struct checkout_opts *opts)
587 {
588 return run_add_interactive(revision, "--patch=checkout", pathspec);
589 }
590
591 struct tracking_name_data {
592 const char *name;
593 char *remote;
594 int unique;
595 };
596
597 static int check_tracking_name(const char *refname, const unsigned char *sha1,
598 int flags, void *cb_data)
599 {
600 struct tracking_name_data *cb = cb_data;
601 const char *slash;
602
603 if (prefixcmp(refname, "refs/remotes/"))
604 return 0;
605 slash = strchr(refname + 13, '/');
606 if (!slash || strcmp(slash + 1, cb->name))
607 return 0;
608 if (cb->remote) {
609 cb->unique = 0;
610 return 0;
611 }
612 cb->remote = xstrdup(refname);
613 return 0;
614 }
615
616 static const char *unique_tracking_name(const char *name)
617 {
618 struct tracking_name_data cb_data = { name, NULL, 1 };
619 for_each_ref(check_tracking_name, &cb_data);
620 if (cb_data.unique)
621 return cb_data.remote;
622 free(cb_data.remote);
623 return NULL;
624 }
625
626 int cmd_checkout(int argc, const char **argv, const char *prefix)
627 {
628 struct checkout_opts opts;
629 unsigned char rev[20];
630 const char *arg;
631 struct branch_info new;
632 struct tree *source_tree = NULL;
633 char *conflict_style = NULL;
634 int patch_mode = 0;
635 int dwim_new_local_branch = 1;
636 struct option options[] = {
637 OPT__QUIET(&opts.quiet),
638 OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
639 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
640 OPT_SET_INT('t', "track", &opts.track, "track",
641 BRANCH_TRACK_EXPLICIT),
642 OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
643 2),
644 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
645 3),
646 OPT_BOOLEAN('f', "force", &opts.force, "force"),
647 OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
648 OPT_STRING(0, "conflict", &conflict_style, "style",
649 "conflict style (merge or diff3)"),
650 OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
651 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
652 "second guess 'git checkout no-such-branch'",
653 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
654 OPT_END(),
655 };
656 int has_dash_dash;
657
658 memset(&opts, 0, sizeof(opts));
659 memset(&new, 0, sizeof(new));
660
661 git_config(git_checkout_config, NULL);
662
663 opts.track = BRANCH_TRACK_UNSPECIFIED;
664
665 argc = parse_options(argc, argv, prefix, options, checkout_usage,
666 PARSE_OPT_KEEP_DASHDASH);
667
668 if (patch_mode && (opts.track > 0 || opts.new_branch
669 || opts.new_branch_log || opts.merge || opts.force))
670 die ("--patch is incompatible with all other options");
671
672 /* --track without -b should DWIM */
673 if (0 < opts.track && !opts.new_branch) {
674 const char *argv0 = argv[0];
675 if (!argc || !strcmp(argv0, "--"))
676 die ("--track needs a branch name");
677 if (!prefixcmp(argv0, "refs/"))
678 argv0 += 5;
679 if (!prefixcmp(argv0, "remotes/"))
680 argv0 += 8;
681 argv0 = strchr(argv0, '/');
682 if (!argv0 || !argv0[1])
683 die ("Missing branch name; try -b");
684 opts.new_branch = argv0 + 1;
685 }
686
687 if (conflict_style) {
688 opts.merge = 1; /* implied */
689 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
690 }
691
692 if (opts.force && opts.merge)
693 die("git checkout: -f and -m are incompatible");
694
695 /*
696 * case 1: git checkout <ref> -- [<paths>]
697 *
698 * <ref> must be a valid tree, everything after the '--' must be
699 * a path.
700 *
701 * case 2: git checkout -- [<paths>]
702 *
703 * everything after the '--' must be paths.
704 *
705 * case 3: git checkout <something> [<paths>]
706 *
707 * With no paths, if <something> is a commit, that is to
708 * switch to the branch or detach HEAD at it. As a special case,
709 * if <something> is A...B (missing A or B means HEAD but you can
710 * omit at most one side), and if there is a unique merge base
711 * between A and B, A...B names that merge base.
712 *
713 * With no paths, if <something> is _not_ a commit, no -t nor -b
714 * was given, and there is a tracking branch whose name is
715 * <something> in one and only one remote, then this is a short-hand
716 * to fork local <something> from that remote tracking branch.
717 *
718 * Otherwise <something> shall not be ambiguous.
719 * - If it's *only* a reference, treat it like case (1).
720 * - If it's only a path, treat it like case (2).
721 * - else: fail.
722 *
723 */
724 if (argc) {
725 if (!strcmp(argv[0], "--")) { /* case (2) */
726 argv++;
727 argc--;
728 goto no_reference;
729 }
730
731 arg = argv[0];
732 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
733
734 if (!strcmp(arg, "-"))
735 arg = "@{-1}";
736
737 if (get_sha1_mb(arg, rev)) {
738 if (has_dash_dash) /* case (1) */
739 die("invalid reference: %s", arg);
740 if (!patch_mode &&
741 dwim_new_local_branch &&
742 opts.track == BRANCH_TRACK_UNSPECIFIED &&
743 !opts.new_branch &&
744 !check_filename(NULL, arg) &&
745 argc == 1) {
746 const char *remote = unique_tracking_name(arg);
747 if (!remote || get_sha1(remote, rev))
748 goto no_reference;
749 opts.new_branch = arg;
750 arg = remote;
751 /* DWIMmed to create local branch */
752 }
753 else
754 goto no_reference;
755 }
756
757 /* we can't end up being in (2) anymore, eat the argument */
758 argv++;
759 argc--;
760
761 new.name = arg;
762 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
763 setup_branch_path(&new);
764
765 if ((check_ref_format(new.path) == CHECK_REF_FORMAT_OK) &&
766 resolve_ref(new.path, rev, 1, NULL))
767 ;
768 else
769 new.path = NULL;
770 parse_commit(new.commit);
771 source_tree = new.commit->tree;
772 } else
773 source_tree = parse_tree_indirect(rev);
774
775 if (!source_tree) /* case (1): want a tree */
776 die("reference is not a tree: %s", arg);
777 if (!has_dash_dash) {/* case (3 -> 1) */
778 /*
779 * Do not complain the most common case
780 * git checkout branch
781 * even if there happen to be a file called 'branch';
782 * it would be extremely annoying.
783 */
784 if (argc)
785 verify_non_filename(NULL, arg);
786 }
787 else {
788 argv++;
789 argc--;
790 }
791 }
792
793 no_reference:
794
795 if (opts.track == BRANCH_TRACK_UNSPECIFIED)
796 opts.track = git_branch_track;
797
798 if (argc) {
799 const char **pathspec = get_pathspec(prefix, argv);
800
801 if (!pathspec)
802 die("invalid path specification");
803
804 if (patch_mode)
805 return interactive_checkout(new.name, pathspec, &opts);
806
807 /* Checkout paths */
808 if (opts.new_branch) {
809 if (argc == 1) {
810 die("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
811 } else {
812 die("git checkout: updating paths is incompatible with switching branches.");
813 }
814 }
815
816 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
817 die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
818
819 return checkout_paths(source_tree, pathspec, &opts);
820 }
821
822 if (patch_mode)
823 return interactive_checkout(new.name, NULL, &opts);
824
825 if (opts.new_branch) {
826 struct strbuf buf = STRBUF_INIT;
827 if (strbuf_check_branch_ref(&buf, opts.new_branch))
828 die("git checkout: we do not like '%s' as a branch name.",
829 opts.new_branch);
830 if (!get_sha1(buf.buf, rev))
831 die("git checkout: branch %s already exists", opts.new_branch);
832 strbuf_release(&buf);
833 }
834
835 if (new.name && !new.commit) {
836 die("Cannot switch branch to a non-commit.");
837 }
838 if (opts.writeout_stage)
839 die("--ours/--theirs is incompatible with switching branches.");
840
841 return switch_branches(&opts, &new);
842 }