Merge branch 'rs/path-name-safety-cleanup' into next
[git] / builtin / checkout.c
1 #include "builtin.h"
2 #include "lockfile.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 #include "submodule-config.h"
22 #include "submodule.h"
23
24 static const char * const checkout_usage[] = {
25         N_("git checkout [<options>] <branch>"),
26         N_("git checkout [<options>] [<branch>] -- <file>..."),
27         NULL,
28 };
29
30 struct checkout_opts {
31         int patch_mode;
32         int quiet;
33         int merge;
34         int force;
35         int force_detach;
36         int writeout_stage;
37         int overwrite_ignore;
38         int ignore_skipworktree;
39         int ignore_other_worktrees;
40         int show_progress;
41
42         const char *new_branch;
43         const char *new_branch_force;
44         const char *new_orphan_branch;
45         int new_branch_log;
46         enum branch_track track;
47         struct diff_options diff_options;
48
49         int branch_exists;
50         const char *prefix;
51         struct pathspec pathspec;
52         struct tree *source_tree;
53 };
54
55 static int post_checkout_hook(struct commit *old, struct commit *new,
56                               int changed)
57 {
58         return run_hook_le(NULL, "post-checkout",
59                            oid_to_hex(old ? &old->object.oid : &null_oid),
60                            oid_to_hex(new ? &new->object.oid : &null_oid),
61                            changed ? "1" : "0", NULL);
62         /* "new" can be NULL when checking out from the index before
63            a commit exists. */
64
65 }
66
67 static int update_some(const unsigned char *sha1, struct strbuf *base,
68                 const char *pathname, unsigned mode, int stage, void *context)
69 {
70         int len;
71         struct cache_entry *ce;
72         int pos;
73
74         if (S_ISDIR(mode))
75                 return READ_TREE_RECURSIVE;
76
77         len = base->len + strlen(pathname);
78         ce = xcalloc(1, cache_entry_size(len));
79         hashcpy(ce->oid.hash, sha1);
80         memcpy(ce->name, base->buf, base->len);
81         memcpy(ce->name + base->len, pathname, len - base->len);
82         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
83         ce->ce_namelen = len;
84         ce->ce_mode = create_ce_mode(mode);
85
86         /*
87          * If the entry is the same as the current index, we can leave the old
88          * entry in place. Whether it is UPTODATE or not, checkout_entry will
89          * do the right thing.
90          */
91         pos = cache_name_pos(ce->name, ce->ce_namelen);
92         if (pos >= 0) {
93                 struct cache_entry *old = active_cache[pos];
94                 if (ce->ce_mode == old->ce_mode &&
95                     !oidcmp(&ce->oid, &old->oid)) {
96                         old->ce_flags |= CE_UPDATE;
97                         free(ce);
98                         return 0;
99                 }
100         }
101
102         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
103         return 0;
104 }
105
106 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
107 {
108         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
109
110         /* update the index with the given tree's info
111          * for all args, expanding wildcards, and exit
112          * with any non-zero return code.
113          */
114         return 0;
115 }
116
117 static int skip_same_name(const struct cache_entry *ce, int pos)
118 {
119         while (++pos < active_nr &&
120                !strcmp(active_cache[pos]->name, ce->name))
121                 ; /* skip */
122         return pos;
123 }
124
125 static int check_stage(int stage, const struct cache_entry *ce, int pos)
126 {
127         while (pos < active_nr &&
128                !strcmp(active_cache[pos]->name, ce->name)) {
129                 if (ce_stage(active_cache[pos]) == stage)
130                         return 0;
131                 pos++;
132         }
133         if (stage == 2)
134                 return error(_("path '%s' does not have our version"), ce->name);
135         else
136                 return error(_("path '%s' does not have their version"), ce->name);
137 }
138
139 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
140 {
141         unsigned seen = 0;
142         const char *name = ce->name;
143
144         while (pos < active_nr) {
145                 ce = active_cache[pos];
146                 if (strcmp(name, ce->name))
147                         break;
148                 seen |= (1 << ce_stage(ce));
149                 pos++;
150         }
151         if ((stages & seen) != stages)
152                 return error(_("path '%s' does not have all necessary versions"),
153                              name);
154         return 0;
155 }
156
157 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
158                           const struct checkout *state)
159 {
160         while (pos < active_nr &&
161                !strcmp(active_cache[pos]->name, ce->name)) {
162                 if (ce_stage(active_cache[pos]) == stage)
163                         return checkout_entry(active_cache[pos], state, NULL);
164                 pos++;
165         }
166         if (stage == 2)
167                 return error(_("path '%s' does not have our version"), ce->name);
168         else
169                 return error(_("path '%s' does not have their version"), ce->name);
170 }
171
172 static int checkout_merged(int pos, const struct checkout *state)
173 {
174         struct cache_entry *ce = active_cache[pos];
175         const char *path = ce->name;
176         mmfile_t ancestor, ours, theirs;
177         int status;
178         struct object_id oid;
179         mmbuffer_t result_buf;
180         struct object_id threeway[3];
181         unsigned mode = 0;
182
183         memset(threeway, 0, sizeof(threeway));
184         while (pos < active_nr) {
185                 int stage;
186                 stage = ce_stage(ce);
187                 if (!stage || strcmp(path, ce->name))
188                         break;
189                 oidcpy(&threeway[stage - 1], &ce->oid);
190                 if (stage == 2)
191                         mode = create_ce_mode(ce->ce_mode);
192                 pos++;
193                 ce = active_cache[pos];
194         }
195         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
196                 return error(_("path '%s' does not have necessary versions"), path);
197
198         read_mmblob(&ancestor, &threeway[0]);
199         read_mmblob(&ours, &threeway[1]);
200         read_mmblob(&theirs, &threeway[2]);
201
202         /*
203          * NEEDSWORK: re-create conflicts from merges with
204          * merge.renormalize set, too
205          */
206         status = ll_merge(&result_buf, path, &ancestor, "base",
207                           &ours, "ours", &theirs, "theirs", NULL);
208         free(ancestor.ptr);
209         free(ours.ptr);
210         free(theirs.ptr);
211         if (status < 0 || !result_buf.ptr) {
212                 free(result_buf.ptr);
213                 return error(_("path '%s': cannot merge"), path);
214         }
215
216         /*
217          * NEEDSWORK:
218          * There is absolutely no reason to write this as a blob object
219          * and create a phony cache entry just to leak.  This hack is
220          * primarily to get to the write_entry() machinery that massages
221          * the contents to work-tree format and writes out which only
222          * allows it for a cache entry.  The code in write_entry() needs
223          * to be refactored to allow us to feed a <buffer, size, mode>
224          * instead of a cache entry.  Such a refactoring would help
225          * merge_recursive as well (it also writes the merge result to the
226          * object database even when it may contain conflicts).
227          */
228         if (write_sha1_file(result_buf.ptr, result_buf.size,
229                             blob_type, oid.hash))
230                 die(_("Unable to add merge result for '%s'"), path);
231         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
232         if (!ce)
233                 die(_("make_cache_entry failed for path '%s'"), path);
234         status = checkout_entry(ce, state, NULL);
235         return status;
236 }
237
238 static int checkout_paths(const struct checkout_opts *opts,
239                           const char *revision)
240 {
241         int pos;
242         struct checkout state = CHECKOUT_INIT;
243         static char *ps_matched;
244         struct object_id rev;
245         struct commit *head;
246         int errs = 0;
247         struct lock_file *lock_file;
248
249         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
250                 die(_("'%s' cannot be used with updating paths"), "--track");
251
252         if (opts->new_branch_log)
253                 die(_("'%s' cannot be used with updating paths"), "-l");
254
255         if (opts->force && opts->patch_mode)
256                 die(_("'%s' cannot be used with updating paths"), "-f");
257
258         if (opts->force_detach)
259                 die(_("'%s' cannot be used with updating paths"), "--detach");
260
261         if (opts->merge && opts->patch_mode)
262                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
263
264         if (opts->force && opts->merge)
265                 die(_("'%s' cannot be used with %s"), "-f", "-m");
266
267         if (opts->new_branch)
268                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
269                     opts->new_branch);
270
271         if (opts->patch_mode)
272                 return run_add_interactive(revision, "--patch=checkout",
273                                            &opts->pathspec);
274
275         lock_file = xcalloc(1, sizeof(struct lock_file));
276
277         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
278         if (read_cache_preload(&opts->pathspec) < 0)
279                 return error(_("index file corrupt"));
280
281         if (opts->source_tree)
282                 read_tree_some(opts->source_tree, &opts->pathspec);
283
284         ps_matched = xcalloc(opts->pathspec.nr, 1);
285
286         /*
287          * Make sure all pathspecs participated in locating the paths
288          * to be checked out.
289          */
290         for (pos = 0; pos < active_nr; pos++) {
291                 struct cache_entry *ce = active_cache[pos];
292                 ce->ce_flags &= ~CE_MATCHED;
293                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
294                         continue;
295                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
296                         /*
297                          * "git checkout tree-ish -- path", but this entry
298                          * is in the original index; it will not be checked
299                          * out to the working tree and it does not matter
300                          * if pathspec matched this entry.  We will not do
301                          * anything to this entry at all.
302                          */
303                         continue;
304                 /*
305                  * Either this entry came from the tree-ish we are
306                  * checking the paths out of, or we are checking out
307                  * of the index.
308                  *
309                  * If it comes from the tree-ish, we already know it
310                  * matches the pathspec and could just stamp
311                  * CE_MATCHED to it from update_some(). But we still
312                  * need ps_matched and read_tree_recursive (and
313                  * eventually tree_entry_interesting) cannot fill
314                  * ps_matched yet. Once it can, we can avoid calling
315                  * match_pathspec() for _all_ entries when
316                  * opts->source_tree != NULL.
317                  */
318                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
319                         ce->ce_flags |= CE_MATCHED;
320         }
321
322         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
323                 free(ps_matched);
324                 return 1;
325         }
326         free(ps_matched);
327
328         /* "checkout -m path" to recreate conflicted state */
329         if (opts->merge)
330                 unmerge_marked_index(&the_index);
331
332         /* Any unmerged paths? */
333         for (pos = 0; pos < active_nr; pos++) {
334                 const struct cache_entry *ce = active_cache[pos];
335                 if (ce->ce_flags & CE_MATCHED) {
336                         if (!ce_stage(ce))
337                                 continue;
338                         if (opts->force) {
339                                 warning(_("path '%s' is unmerged"), ce->name);
340                         } else if (opts->writeout_stage) {
341                                 errs |= check_stage(opts->writeout_stage, ce, pos);
342                         } else if (opts->merge) {
343                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
344                         } else {
345                                 errs = 1;
346                                 error(_("path '%s' is unmerged"), ce->name);
347                         }
348                         pos = skip_same_name(ce, pos) - 1;
349                 }
350         }
351         if (errs)
352                 return 1;
353
354         /* Now we are committed to check them out */
355         state.force = 1;
356         state.refresh_cache = 1;
357         state.istate = &the_index;
358         for (pos = 0; pos < active_nr; pos++) {
359                 struct cache_entry *ce = active_cache[pos];
360                 if (ce->ce_flags & CE_MATCHED) {
361                         if (!ce_stage(ce)) {
362                                 errs |= checkout_entry(ce, &state, NULL);
363                                 continue;
364                         }
365                         if (opts->writeout_stage)
366                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
367                         else if (opts->merge)
368                                 errs |= checkout_merged(pos, &state);
369                         pos = skip_same_name(ce, pos) - 1;
370                 }
371         }
372
373         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
374                 die(_("unable to write new index file"));
375
376         read_ref_full("HEAD", 0, rev.hash, NULL);
377         head = lookup_commit_reference_gently(rev.hash, 1);
378
379         errs |= post_checkout_hook(head, head, 0);
380         return errs;
381 }
382
383 static void show_local_changes(struct object *head,
384                                const struct diff_options *opts)
385 {
386         struct rev_info rev;
387         /* I think we want full paths, even if we're in a subdirectory. */
388         init_revisions(&rev, NULL);
389         rev.diffopt.flags = opts->flags;
390         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
391         diff_setup_done(&rev.diffopt);
392         add_pending_object(&rev, head, NULL);
393         run_diff_index(&rev, 0);
394 }
395
396 static void describe_detached_head(const char *msg, struct commit *commit)
397 {
398         struct strbuf sb = STRBUF_INIT;
399         if (!parse_commit(commit))
400                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
401         fprintf(stderr, "%s %s... %s\n", msg,
402                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
403         strbuf_release(&sb);
404 }
405
406 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
407                       int worktree, int *writeout_error)
408 {
409         struct unpack_trees_options opts;
410         struct tree_desc tree_desc;
411
412         memset(&opts, 0, sizeof(opts));
413         opts.head_idx = -1;
414         opts.update = worktree;
415         opts.skip_unmerged = !worktree;
416         opts.reset = 1;
417         opts.merge = 1;
418         opts.fn = oneway_merge;
419         opts.verbose_update = o->show_progress;
420         opts.src_index = &the_index;
421         opts.dst_index = &the_index;
422         parse_tree(tree);
423         init_tree_desc(&tree_desc, tree->buffer, tree->size);
424         switch (unpack_trees(1, &tree_desc, &opts)) {
425         case -2:
426                 *writeout_error = 1;
427                 /*
428                  * We return 0 nevertheless, as the index is all right
429                  * and more importantly we have made best efforts to
430                  * update paths in the work tree, and we cannot revert
431                  * them.
432                  */
433         case 0:
434                 return 0;
435         default:
436                 return 128;
437         }
438 }
439
440 struct branch_info {
441         const char *name; /* The short name used */
442         const char *path; /* The full name of a real branch */
443         struct commit *commit; /* The named commit */
444         /*
445          * if not null the branch is detached because it's already
446          * checked out in this checkout
447          */
448         char *checkout;
449 };
450
451 static void setup_branch_path(struct branch_info *branch)
452 {
453         struct strbuf buf = STRBUF_INIT;
454
455         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
456         if (strcmp(buf.buf, branch->name))
457                 branch->name = xstrdup(buf.buf);
458         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
459         branch->path = strbuf_detach(&buf, NULL);
460 }
461
462 static int merge_working_tree(const struct checkout_opts *opts,
463                               struct branch_info *old,
464                               struct branch_info *new,
465                               int *writeout_error)
466 {
467         int ret;
468         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
469
470         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
471         if (read_cache_preload(NULL) < 0)
472                 return error(_("index file corrupt"));
473
474         resolve_undo_clear();
475         if (opts->force) {
476                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
477                 if (ret)
478                         return ret;
479         } else {
480                 struct tree_desc trees[2];
481                 struct tree *tree;
482                 struct unpack_trees_options topts;
483
484                 memset(&topts, 0, sizeof(topts));
485                 topts.head_idx = -1;
486                 topts.src_index = &the_index;
487                 topts.dst_index = &the_index;
488
489                 setup_unpack_trees_porcelain(&topts, "checkout");
490
491                 refresh_cache(REFRESH_QUIET);
492
493                 if (unmerged_cache()) {
494                         error(_("you need to resolve your current index first"));
495                         return 1;
496                 }
497
498                 /* 2-way merge to the new branch */
499                 topts.initial_checkout = is_cache_unborn();
500                 topts.update = 1;
501                 topts.merge = 1;
502                 topts.gently = opts->merge && old->commit;
503                 topts.verbose_update = opts->show_progress;
504                 topts.fn = twoway_merge;
505                 if (opts->overwrite_ignore) {
506                         topts.dir = xcalloc(1, sizeof(*topts.dir));
507                         topts.dir->flags |= DIR_SHOW_IGNORED;
508                         setup_standard_excludes(topts.dir);
509                 }
510                 tree = parse_tree_indirect(old->commit ?
511                                            old->commit->object.oid.hash :
512                                            EMPTY_TREE_SHA1_BIN);
513                 init_tree_desc(&trees[0], tree->buffer, tree->size);
514                 tree = parse_tree_indirect(new->commit->object.oid.hash);
515                 init_tree_desc(&trees[1], tree->buffer, tree->size);
516
517                 ret = unpack_trees(2, trees, &topts);
518                 if (ret == -1) {
519                         /*
520                          * Unpack couldn't do a trivial merge; either
521                          * give up or do a real merge, depending on
522                          * whether the merge flag was used.
523                          */
524                         struct tree *result;
525                         struct tree *work;
526                         struct merge_options o;
527                         if (!opts->merge)
528                                 return 1;
529
530                         /*
531                          * Without old->commit, the below is the same as
532                          * the two-tree unpack we already tried and failed.
533                          */
534                         if (!old->commit)
535                                 return 1;
536
537                         /* Do more real merge */
538
539                         /*
540                          * We update the index fully, then write the
541                          * tree from the index, then merge the new
542                          * branch with the current tree, with the old
543                          * branch as the base. Then we reset the index
544                          * (but not the working tree) to the new
545                          * branch, leaving the working tree as the
546                          * merged version, but skipping unmerged
547                          * entries in the index.
548                          */
549
550                         add_files_to_cache(NULL, NULL, 0);
551                         /*
552                          * NEEDSWORK: carrying over local changes
553                          * when branches have different end-of-line
554                          * normalization (or clean+smudge rules) is
555                          * a pain; plumb in an option to set
556                          * o.renormalize?
557                          */
558                         init_merge_options(&o);
559                         o.verbosity = 0;
560                         work = write_tree_from_memory(&o);
561
562                         ret = reset_tree(new->commit->tree, opts, 1,
563                                          writeout_error);
564                         if (ret)
565                                 return ret;
566                         o.ancestor = old->name;
567                         o.branch1 = new->name;
568                         o.branch2 = "local";
569                         ret = merge_trees(&o, new->commit->tree, work,
570                                 old->commit->tree, &result);
571                         if (ret < 0)
572                                 exit(128);
573                         ret = reset_tree(new->commit->tree, opts, 0,
574                                          writeout_error);
575                         strbuf_release(&o.obuf);
576                         if (ret)
577                                 return ret;
578                 }
579         }
580
581         if (!active_cache_tree)
582                 active_cache_tree = cache_tree();
583
584         if (!cache_tree_fully_valid(active_cache_tree))
585                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
586
587         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
588                 die(_("unable to write new index file"));
589
590         if (!opts->force && !opts->quiet)
591                 show_local_changes(&new->commit->object, &opts->diff_options);
592
593         return 0;
594 }
595
596 static void report_tracking(struct branch_info *new)
597 {
598         struct strbuf sb = STRBUF_INIT;
599         struct branch *branch = branch_get(new->name);
600
601         if (!format_tracking_info(branch, &sb))
602                 return;
603         fputs(sb.buf, stdout);
604         strbuf_release(&sb);
605 }
606
607 static void update_refs_for_switch(const struct checkout_opts *opts,
608                                    struct branch_info *old,
609                                    struct branch_info *new)
610 {
611         struct strbuf msg = STRBUF_INIT;
612         const char *old_desc, *reflog_msg;
613         if (opts->new_branch) {
614                 if (opts->new_orphan_branch) {
615                         char *refname;
616
617                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
618                         if (opts->new_branch_log &&
619                             !should_autocreate_reflog(refname)) {
620                                 int ret;
621                                 struct strbuf err = STRBUF_INIT;
622
623                                 ret = safe_create_reflog(refname, 1, &err);
624                                 if (ret) {
625                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
626                                                 opts->new_orphan_branch, err.buf);
627                                         strbuf_release(&err);
628                                         free(refname);
629                                         return;
630                                 }
631                                 strbuf_release(&err);
632                         }
633                         free(refname);
634                 }
635                 else
636                         create_branch(opts->new_branch, new->name,
637                                       opts->new_branch_force ? 1 : 0,
638                                       opts->new_branch_log,
639                                       opts->new_branch_force ? 1 : 0,
640                                       opts->quiet,
641                                       opts->track);
642                 new->name = opts->new_branch;
643                 setup_branch_path(new);
644         }
645
646         old_desc = old->name;
647         if (!old_desc && old->commit)
648                 old_desc = oid_to_hex(&old->commit->object.oid);
649
650         reflog_msg = getenv("GIT_REFLOG_ACTION");
651         if (!reflog_msg)
652                 strbuf_addf(&msg, "checkout: moving from %s to %s",
653                         old_desc ? old_desc : "(invalid)", new->name);
654         else
655                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
656
657         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
658                 /* Nothing to do. */
659         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
660                 update_ref(msg.buf, "HEAD", new->commit->object.oid.hash, NULL,
661                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
662                 if (!opts->quiet) {
663                         if (old->path &&
664                             advice_detached_head && !opts->force_detach)
665                                 detach_advice(new->name);
666                         describe_detached_head(_("HEAD is now at"), new->commit);
667                 }
668         } else if (new->path) { /* Switch branches. */
669                 if (create_symref("HEAD", new->path, msg.buf) < 0)
670                         die(_("unable to update HEAD"));
671                 if (!opts->quiet) {
672                         if (old->path && !strcmp(new->path, old->path)) {
673                                 if (opts->new_branch_force)
674                                         fprintf(stderr, _("Reset branch '%s'\n"),
675                                                 new->name);
676                                 else
677                                         fprintf(stderr, _("Already on '%s'\n"),
678                                                 new->name);
679                         } else if (opts->new_branch) {
680                                 if (opts->branch_exists)
681                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
682                                 else
683                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
684                         } else {
685                                 fprintf(stderr, _("Switched to branch '%s'\n"),
686                                         new->name);
687                         }
688                 }
689                 if (old->path && old->name) {
690                         if (!ref_exists(old->path) && reflog_exists(old->path))
691                                 delete_reflog(old->path);
692                 }
693         }
694         remove_branch_state();
695         strbuf_release(&msg);
696         if (!opts->quiet &&
697             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
698                 report_tracking(new);
699 }
700
701 static int add_pending_uninteresting_ref(const char *refname,
702                                          const struct object_id *oid,
703                                          int flags, void *cb_data)
704 {
705         add_pending_sha1(cb_data, refname, oid->hash, UNINTERESTING);
706         return 0;
707 }
708
709 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
710 {
711         strbuf_addstr(sb, "  ");
712         strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
713         strbuf_addch(sb, ' ');
714         if (!parse_commit(commit))
715                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
716         strbuf_addch(sb, '\n');
717 }
718
719 #define ORPHAN_CUTOFF 4
720 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
721 {
722         struct commit *c, *last = NULL;
723         struct strbuf sb = STRBUF_INIT;
724         int lost = 0;
725         while ((c = get_revision(revs)) != NULL) {
726                 if (lost < ORPHAN_CUTOFF)
727                         describe_one_orphan(&sb, c);
728                 last = c;
729                 lost++;
730         }
731         if (ORPHAN_CUTOFF < lost) {
732                 int more = lost - ORPHAN_CUTOFF;
733                 if (more == 1)
734                         describe_one_orphan(&sb, last);
735                 else
736                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
737         }
738
739         fprintf(stderr,
740                 Q_(
741                 /* The singular version */
742                 "Warning: you are leaving %d commit behind, "
743                 "not connected to\n"
744                 "any of your branches:\n\n"
745                 "%s\n",
746                 /* The plural version */
747                 "Warning: you are leaving %d commits behind, "
748                 "not connected to\n"
749                 "any of your branches:\n\n"
750                 "%s\n",
751                 /* Give ngettext() the count */
752                 lost),
753                 lost,
754                 sb.buf);
755         strbuf_release(&sb);
756
757         if (advice_detached_head)
758                 fprintf(stderr,
759                         Q_(
760                         /* The singular version */
761                         "If you want to keep it by creating a new branch, "
762                         "this may be a good time\nto do so with:\n\n"
763                         " git branch <new-branch-name> %s\n\n",
764                         /* The plural version */
765                         "If you want to keep them by creating a new branch, "
766                         "this may be a good time\nto do so with:\n\n"
767                         " git branch <new-branch-name> %s\n\n",
768                         /* Give ngettext() the count */
769                         lost),
770                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
771 }
772
773 /*
774  * We are about to leave commit that was at the tip of a detached
775  * HEAD.  If it is not reachable from any ref, this is the last chance
776  * for the user to do so without resorting to reflog.
777  */
778 static void orphaned_commit_warning(struct commit *old, struct commit *new)
779 {
780         struct rev_info revs;
781         struct object *object = &old->object;
782         struct object_array refs;
783
784         init_revisions(&revs, NULL);
785         setup_revisions(0, NULL, &revs, NULL);
786
787         object->flags &= ~UNINTERESTING;
788         add_pending_object(&revs, object, oid_to_hex(&object->oid));
789
790         for_each_ref(add_pending_uninteresting_ref, &revs);
791         add_pending_sha1(&revs, "HEAD", new->object.oid.hash, UNINTERESTING);
792
793         refs = revs.pending;
794         revs.leak_pending = 1;
795
796         if (prepare_revision_walk(&revs))
797                 die(_("internal error in revision walk"));
798         if (!(old->object.flags & UNINTERESTING))
799                 suggest_reattach(old, &revs);
800         else
801                 describe_detached_head(_("Previous HEAD position was"), old);
802
803         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
804         free(refs.objects);
805 }
806
807 static int switch_branches(const struct checkout_opts *opts,
808                            struct branch_info *new)
809 {
810         int ret = 0;
811         struct branch_info old;
812         void *path_to_free;
813         struct object_id rev;
814         int flag, writeout_error = 0;
815         memset(&old, 0, sizeof(old));
816         old.path = path_to_free = resolve_refdup("HEAD", 0, rev.hash, &flag);
817         old.commit = lookup_commit_reference_gently(rev.hash, 1);
818         if (!(flag & REF_ISSYMREF))
819                 old.path = NULL;
820
821         if (old.path)
822                 skip_prefix(old.path, "refs/heads/", &old.name);
823
824         if (!new->name) {
825                 new->name = "HEAD";
826                 new->commit = old.commit;
827                 if (!new->commit)
828                         die(_("You are on a branch yet to be born"));
829                 parse_commit_or_die(new->commit);
830         }
831
832         ret = merge_working_tree(opts, &old, new, &writeout_error);
833         if (ret) {
834                 free(path_to_free);
835                 return ret;
836         }
837
838         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
839                 orphaned_commit_warning(old.commit, new->commit);
840
841         update_refs_for_switch(opts, &old, new);
842
843         ret = post_checkout_hook(old.commit, new->commit, 1);
844         free(path_to_free);
845         return ret || writeout_error;
846 }
847
848 static int git_checkout_config(const char *var, const char *value, void *cb)
849 {
850         if (!strcmp(var, "diff.ignoresubmodules")) {
851                 struct checkout_opts *opts = cb;
852                 handle_ignore_submodules_arg(&opts->diff_options, value);
853                 return 0;
854         }
855
856         if (starts_with(var, "submodule."))
857                 return parse_submodule_config_option(var, value);
858
859         return git_xmerge_config(var, value, NULL);
860 }
861
862 struct tracking_name_data {
863         /* const */ char *src_ref;
864         char *dst_ref;
865         struct object_id *dst_oid;
866         int unique;
867 };
868
869 static int check_tracking_name(struct remote *remote, void *cb_data)
870 {
871         struct tracking_name_data *cb = cb_data;
872         struct refspec query;
873         memset(&query, 0, sizeof(struct refspec));
874         query.src = cb->src_ref;
875         if (remote_find_tracking(remote, &query) ||
876             get_oid(query.dst, cb->dst_oid)) {
877                 free(query.dst);
878                 return 0;
879         }
880         if (cb->dst_ref) {
881                 free(query.dst);
882                 cb->unique = 0;
883                 return 0;
884         }
885         cb->dst_ref = query.dst;
886         return 0;
887 }
888
889 static const char *unique_tracking_name(const char *name, struct object_id *oid)
890 {
891         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
892         char src_ref[PATH_MAX];
893         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
894         cb_data.src_ref = src_ref;
895         cb_data.dst_oid = oid;
896         for_each_remote(check_tracking_name, &cb_data);
897         if (cb_data.unique)
898                 return cb_data.dst_ref;
899         free(cb_data.dst_ref);
900         return NULL;
901 }
902
903 static int parse_branchname_arg(int argc, const char **argv,
904                                 int dwim_new_local_branch_ok,
905                                 struct branch_info *new,
906                                 struct checkout_opts *opts,
907                                 struct object_id *rev)
908 {
909         struct tree **source_tree = &opts->source_tree;
910         const char **new_branch = &opts->new_branch;
911         int argcount = 0;
912         struct object_id branch_rev;
913         const char *arg;
914         int dash_dash_pos;
915         int has_dash_dash = 0;
916         int i;
917
918         /*
919          * case 1: git checkout <ref> -- [<paths>]
920          *
921          *   <ref> must be a valid tree, everything after the '--' must be
922          *   a path.
923          *
924          * case 2: git checkout -- [<paths>]
925          *
926          *   everything after the '--' must be paths.
927          *
928          * case 3: git checkout <something> [--]
929          *
930          *   (a) If <something> is a commit, that is to
931          *       switch to the branch or detach HEAD at it.  As a special case,
932          *       if <something> is A...B (missing A or B means HEAD but you can
933          *       omit at most one side), and if there is a unique merge base
934          *       between A and B, A...B names that merge base.
935          *
936          *   (b) If <something> is _not_ a commit, either "--" is present
937          *       or <something> is not a path, no -t or -b was given, and
938          *       and there is a tracking branch whose name is <something>
939          *       in one and only one remote, then this is a short-hand to
940          *       fork local <something> from that remote-tracking branch.
941          *
942          *   (c) Otherwise, if "--" is present, treat it like case (1).
943          *
944          *   (d) Otherwise :
945          *       - if it's a reference, treat it like case (1)
946          *       - else if it's a path, treat it like case (2)
947          *       - else: fail.
948          *
949          * case 4: git checkout <something> <paths>
950          *
951          *   The first argument must not be ambiguous.
952          *   - If it's *only* a reference, treat it like case (1).
953          *   - If it's only a path, treat it like case (2).
954          *   - else: fail.
955          *
956          */
957         if (!argc)
958                 return 0;
959
960         arg = argv[0];
961         dash_dash_pos = -1;
962         for (i = 0; i < argc; i++) {
963                 if (!strcmp(argv[i], "--")) {
964                         dash_dash_pos = i;
965                         break;
966                 }
967         }
968         if (dash_dash_pos == 0)
969                 return 1; /* case (2) */
970         else if (dash_dash_pos == 1)
971                 has_dash_dash = 1; /* case (3) or (1) */
972         else if (dash_dash_pos >= 2)
973                 die(_("only one reference expected, %d given."), dash_dash_pos);
974
975         if (!strcmp(arg, "-"))
976                 arg = "@{-1}";
977
978         if (get_oid_mb(arg, rev)) {
979                 /*
980                  * Either case (3) or (4), with <something> not being
981                  * a commit, or an attempt to use case (1) with an
982                  * invalid ref.
983                  *
984                  * It's likely an error, but we need to find out if
985                  * we should auto-create the branch, case (3).(b).
986                  */
987                 int recover_with_dwim = dwim_new_local_branch_ok;
988
989                 if (!has_dash_dash &&
990                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
991                         recover_with_dwim = 0;
992                 /*
993                  * Accept "git checkout foo" and "git checkout foo --"
994                  * as candidates for dwim.
995                  */
996                 if (!(argc == 1 && !has_dash_dash) &&
997                     !(argc == 2 && has_dash_dash))
998                         recover_with_dwim = 0;
999
1000                 if (recover_with_dwim) {
1001                         const char *remote = unique_tracking_name(arg, rev);
1002                         if (remote) {
1003                                 *new_branch = arg;
1004                                 arg = remote;
1005                                 /* DWIMmed to create local branch, case (3).(b) */
1006                         } else {
1007                                 recover_with_dwim = 0;
1008                         }
1009                 }
1010
1011                 if (!recover_with_dwim) {
1012                         if (has_dash_dash)
1013                                 die(_("invalid reference: %s"), arg);
1014                         return argcount;
1015                 }
1016         }
1017
1018         /* we can't end up being in (2) anymore, eat the argument */
1019         argcount++;
1020         argv++;
1021         argc--;
1022
1023         new->name = arg;
1024         setup_branch_path(new);
1025
1026         if (!check_refname_format(new->path, 0) &&
1027             !read_ref(new->path, branch_rev.hash))
1028                 oidcpy(rev, &branch_rev);
1029         else
1030                 new->path = NULL; /* not an existing branch */
1031
1032         new->commit = lookup_commit_reference_gently(rev->hash, 1);
1033         if (!new->commit) {
1034                 /* not a commit */
1035                 *source_tree = parse_tree_indirect(rev->hash);
1036         } else {
1037                 parse_commit_or_die(new->commit);
1038                 *source_tree = new->commit->tree;
1039         }
1040
1041         if (!*source_tree)                   /* case (1): want a tree */
1042                 die(_("reference is not a tree: %s"), arg);
1043         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1044                 /*
1045                  * Do not complain the most common case
1046                  *      git checkout branch
1047                  * even if there happen to be a file called 'branch';
1048                  * it would be extremely annoying.
1049                  */
1050                 if (argc)
1051                         verify_non_filename(opts->prefix, arg);
1052         } else {
1053                 argcount++;
1054                 argv++;
1055                 argc--;
1056         }
1057
1058         return argcount;
1059 }
1060
1061 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1062 {
1063         int status;
1064         struct strbuf branch_ref = STRBUF_INIT;
1065
1066         if (!opts->new_branch)
1067                 die(_("You are on a branch yet to be born"));
1068         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1069         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1070         strbuf_release(&branch_ref);
1071         if (!opts->quiet)
1072                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1073                         opts->new_branch);
1074         return status;
1075 }
1076
1077 static int checkout_branch(struct checkout_opts *opts,
1078                            struct branch_info *new)
1079 {
1080         if (opts->pathspec.nr)
1081                 die(_("paths cannot be used with switching branches"));
1082
1083         if (opts->patch_mode)
1084                 die(_("'%s' cannot be used with switching branches"),
1085                     "--patch");
1086
1087         if (opts->writeout_stage)
1088                 die(_("'%s' cannot be used with switching branches"),
1089                     "--ours/--theirs");
1090
1091         if (opts->force && opts->merge)
1092                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1093
1094         if (opts->force_detach && opts->new_branch)
1095                 die(_("'%s' cannot be used with '%s'"),
1096                     "--detach", "-b/-B/--orphan");
1097
1098         if (opts->new_orphan_branch) {
1099                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1100                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1101         } else if (opts->force_detach) {
1102                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1103                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1104         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1105                 opts->track = git_branch_track;
1106
1107         if (new->name && !new->commit)
1108                 die(_("Cannot switch branch to a non-commit '%s'"),
1109                     new->name);
1110
1111         if (new->path && !opts->force_detach && !opts->new_branch &&
1112             !opts->ignore_other_worktrees) {
1113                 struct object_id oid;
1114                 int flag;
1115                 char *head_ref = resolve_refdup("HEAD", 0, oid.hash, &flag);
1116                 if (head_ref &&
1117                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1118                         die_if_checked_out(new->path, 1);
1119                 free(head_ref);
1120         }
1121
1122         if (!new->commit && opts->new_branch) {
1123                 struct object_id rev;
1124                 int flag;
1125
1126                 if (!read_ref_full("HEAD", 0, rev.hash, &flag) &&
1127                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1128                         return switch_unborn_to_new_branch(opts);
1129         }
1130         return switch_branches(opts, new);
1131 }
1132
1133 int cmd_checkout(int argc, const char **argv, const char *prefix)
1134 {
1135         struct checkout_opts opts;
1136         struct branch_info new;
1137         char *conflict_style = NULL;
1138         int dwim_new_local_branch = 1;
1139         struct option options[] = {
1140                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1141                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1142                            N_("create and checkout a new branch")),
1143                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1144                            N_("create/reset and checkout a branch")),
1145                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1146                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1147                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1148                         BRANCH_TRACK_EXPLICIT),
1149                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1150                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1151                             2),
1152                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1153                             3),
1154                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1155                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1156                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1157                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1158                            N_("conflict style (merge or diff3)")),
1159                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1160                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1161                          N_("do not limit pathspecs to sparse entries only")),
1162                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1163                                 N_("second guess 'git checkout <no-such-branch>'")),
1164                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1165                          N_("do not check if another worktree is holding the given ref")),
1166                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1167                 OPT_END(),
1168         };
1169
1170         memset(&opts, 0, sizeof(opts));
1171         memset(&new, 0, sizeof(new));
1172         opts.overwrite_ignore = 1;
1173         opts.prefix = prefix;
1174         opts.show_progress = -1;
1175
1176         gitmodules_config();
1177         git_config(git_checkout_config, &opts);
1178
1179         opts.track = BRANCH_TRACK_UNSPECIFIED;
1180
1181         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1182                              PARSE_OPT_KEEP_DASHDASH);
1183
1184         if (opts.show_progress < 0) {
1185                 if (opts.quiet)
1186                         opts.show_progress = 0;
1187                 else
1188                         opts.show_progress = isatty(2);
1189         }
1190
1191         if (conflict_style) {
1192                 opts.merge = 1; /* implied */
1193                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1194         }
1195
1196         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1197                 die(_("-b, -B and --orphan are mutually exclusive"));
1198
1199         /*
1200          * From here on, new_branch will contain the branch to be checked out,
1201          * and new_branch_force and new_orphan_branch will tell us which one of
1202          * -b/-B/--orphan is being used.
1203          */
1204         if (opts.new_branch_force)
1205                 opts.new_branch = opts.new_branch_force;
1206
1207         if (opts.new_orphan_branch)
1208                 opts.new_branch = opts.new_orphan_branch;
1209
1210         /* --track without -b/-B/--orphan should DWIM */
1211         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1212                 const char *argv0 = argv[0];
1213                 if (!argc || !strcmp(argv0, "--"))
1214                         die (_("--track needs a branch name"));
1215                 skip_prefix(argv0, "refs/", &argv0);
1216                 skip_prefix(argv0, "remotes/", &argv0);
1217                 argv0 = strchr(argv0, '/');
1218                 if (!argv0 || !argv0[1])
1219                         die (_("Missing branch name; try -b"));
1220                 opts.new_branch = argv0 + 1;
1221         }
1222
1223         /*
1224          * Extract branch name from command line arguments, so
1225          * all that is left is pathspecs.
1226          *
1227          * Handle
1228          *
1229          *  1) git checkout <tree> -- [<paths>]
1230          *  2) git checkout -- [<paths>]
1231          *  3) git checkout <something> [<paths>]
1232          *
1233          * including "last branch" syntax and DWIM-ery for names of
1234          * remote branches, erroring out for invalid or ambiguous cases.
1235          */
1236         if (argc) {
1237                 struct object_id rev;
1238                 int dwim_ok =
1239                         !opts.patch_mode &&
1240                         dwim_new_local_branch &&
1241                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1242                         !opts.new_branch;
1243                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1244                                              &new, &opts, &rev);
1245                 argv += n;
1246                 argc -= n;
1247         }
1248
1249         if (argc) {
1250                 parse_pathspec(&opts.pathspec, 0,
1251                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1252                                prefix, argv);
1253
1254                 if (!opts.pathspec.nr)
1255                         die(_("invalid path specification"));
1256
1257                 /*
1258                  * Try to give more helpful suggestion.
1259                  * new_branch && argc > 1 will be caught later.
1260                  */
1261                 if (opts.new_branch && argc == 1)
1262                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1263                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1264                             opts.new_branch, argv[0]);
1265
1266                 if (opts.force_detach)
1267                         die(_("git checkout: --detach does not take a path argument '%s'"),
1268                             argv[0]);
1269
1270                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1271                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1272                               "checking out of the index."));
1273         }
1274
1275         if (opts.new_branch) {
1276                 struct strbuf buf = STRBUF_INIT;
1277
1278                 opts.branch_exists =
1279                         validate_new_branchname(opts.new_branch, &buf,
1280                                                 !!opts.new_branch_force,
1281                                                 !!opts.new_branch_force);
1282
1283                 strbuf_release(&buf);
1284         }
1285
1286         if (opts.patch_mode || opts.pathspec.nr)
1287                 return checkout_paths(&opts, new.name);
1288         else
1289                 return checkout_branch(&opts, &new);
1290 }