Merge branch 'cc/git-packet-pm'
[git] / builtin / checkout.c
1 #include "builtin.h"
2 #include "config.h"
3 #include "lockfile.h"
4 #include "parse-options.h"
5 #include "refs.h"
6 #include "commit.h"
7 #include "tree.h"
8 #include "tree-walk.h"
9 #include "cache-tree.h"
10 #include "unpack-trees.h"
11 #include "dir.h"
12 #include "run-command.h"
13 #include "merge-recursive.h"
14 #include "branch.h"
15 #include "diff.h"
16 #include "revision.h"
17 #include "remote.h"
18 #include "blob.h"
19 #include "xdiff-interface.h"
20 #include "ll-merge.h"
21 #include "resolve-undo.h"
22 #include "submodule-config.h"
23 #include "submodule.h"
24
25 static const char * const checkout_usage[] = {
26         N_("git checkout [<options>] <branch>"),
27         N_("git checkout [<options>] [<branch>] -- <file>..."),
28         NULL,
29 };
30
31 struct checkout_opts {
32         int patch_mode;
33         int quiet;
34         int merge;
35         int force;
36         int force_detach;
37         int writeout_stage;
38         int overwrite_ignore;
39         int ignore_skipworktree;
40         int ignore_other_worktrees;
41         int show_progress;
42
43         const char *new_branch;
44         const char *new_branch_force;
45         const char *new_orphan_branch;
46         int new_branch_log;
47         enum branch_track track;
48         struct diff_options diff_options;
49
50         int branch_exists;
51         const char *prefix;
52         struct pathspec pathspec;
53         struct tree *source_tree;
54 };
55
56 static int post_checkout_hook(struct commit *old, struct commit *new,
57                               int changed)
58 {
59         return run_hook_le(NULL, "post-checkout",
60                            oid_to_hex(old ? &old->object.oid : &null_oid),
61                            oid_to_hex(new ? &new->object.oid : &null_oid),
62                            changed ? "1" : "0", NULL);
63         /* "new" can be NULL when checking out from the index before
64            a commit exists. */
65
66 }
67
68 static int update_some(const unsigned char *sha1, struct strbuf *base,
69                 const char *pathname, unsigned mode, int stage, void *context)
70 {
71         int len;
72         struct cache_entry *ce;
73         int pos;
74
75         if (S_ISDIR(mode))
76                 return READ_TREE_RECURSIVE;
77
78         len = base->len + strlen(pathname);
79         ce = xcalloc(1, cache_entry_size(len));
80         hashcpy(ce->oid.hash, sha1);
81         memcpy(ce->name, base->buf, base->len);
82         memcpy(ce->name + base->len, pathname, len - base->len);
83         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
84         ce->ce_namelen = len;
85         ce->ce_mode = create_ce_mode(mode);
86
87         /*
88          * If the entry is the same as the current index, we can leave the old
89          * entry in place. Whether it is UPTODATE or not, checkout_entry will
90          * do the right thing.
91          */
92         pos = cache_name_pos(ce->name, ce->ce_namelen);
93         if (pos >= 0) {
94                 struct cache_entry *old = active_cache[pos];
95                 if (ce->ce_mode == old->ce_mode &&
96                     !oidcmp(&ce->oid, &old->oid)) {
97                         old->ce_flags |= CE_UPDATE;
98                         free(ce);
99                         return 0;
100                 }
101         }
102
103         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
104         return 0;
105 }
106
107 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
108 {
109         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
110
111         /* update the index with the given tree's info
112          * for all args, expanding wildcards, and exit
113          * with any non-zero return code.
114          */
115         return 0;
116 }
117
118 static int skip_same_name(const struct cache_entry *ce, int pos)
119 {
120         while (++pos < active_nr &&
121                !strcmp(active_cache[pos]->name, ce->name))
122                 ; /* skip */
123         return pos;
124 }
125
126 static int check_stage(int stage, const struct cache_entry *ce, int pos)
127 {
128         while (pos < active_nr &&
129                !strcmp(active_cache[pos]->name, ce->name)) {
130                 if (ce_stage(active_cache[pos]) == stage)
131                         return 0;
132                 pos++;
133         }
134         if (stage == 2)
135                 return error(_("path '%s' does not have our version"), ce->name);
136         else
137                 return error(_("path '%s' does not have their version"), ce->name);
138 }
139
140 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
141 {
142         unsigned seen = 0;
143         const char *name = ce->name;
144
145         while (pos < active_nr) {
146                 ce = active_cache[pos];
147                 if (strcmp(name, ce->name))
148                         break;
149                 seen |= (1 << ce_stage(ce));
150                 pos++;
151         }
152         if ((stages & seen) != stages)
153                 return error(_("path '%s' does not have all necessary versions"),
154                              name);
155         return 0;
156 }
157
158 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
159                           const struct checkout *state)
160 {
161         while (pos < active_nr &&
162                !strcmp(active_cache[pos]->name, ce->name)) {
163                 if (ce_stage(active_cache[pos]) == stage)
164                         return checkout_entry(active_cache[pos], state, NULL);
165                 pos++;
166         }
167         if (stage == 2)
168                 return error(_("path '%s' does not have our version"), ce->name);
169         else
170                 return error(_("path '%s' does not have their version"), ce->name);
171 }
172
173 static int checkout_merged(int pos, const struct checkout *state)
174 {
175         struct cache_entry *ce = active_cache[pos];
176         const char *path = ce->name;
177         mmfile_t ancestor, ours, theirs;
178         int status;
179         struct object_id oid;
180         mmbuffer_t result_buf;
181         struct object_id threeway[3];
182         unsigned mode = 0;
183
184         memset(threeway, 0, sizeof(threeway));
185         while (pos < active_nr) {
186                 int stage;
187                 stage = ce_stage(ce);
188                 if (!stage || strcmp(path, ce->name))
189                         break;
190                 oidcpy(&threeway[stage - 1], &ce->oid);
191                 if (stage == 2)
192                         mode = create_ce_mode(ce->ce_mode);
193                 pos++;
194                 ce = active_cache[pos];
195         }
196         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
197                 return error(_("path '%s' does not have necessary versions"), path);
198
199         read_mmblob(&ancestor, &threeway[0]);
200         read_mmblob(&ours, &threeway[1]);
201         read_mmblob(&theirs, &threeway[2]);
202
203         /*
204          * NEEDSWORK: re-create conflicts from merges with
205          * merge.renormalize set, too
206          */
207         status = ll_merge(&result_buf, path, &ancestor, "base",
208                           &ours, "ours", &theirs, "theirs", NULL);
209         free(ancestor.ptr);
210         free(ours.ptr);
211         free(theirs.ptr);
212         if (status < 0 || !result_buf.ptr) {
213                 free(result_buf.ptr);
214                 return error(_("path '%s': cannot merge"), path);
215         }
216
217         /*
218          * NEEDSWORK:
219          * There is absolutely no reason to write this as a blob object
220          * and create a phony cache entry.  This hack is primarily to get
221          * to the write_entry() machinery that massages the contents to
222          * work-tree format and writes out which only allows it for a
223          * cache entry.  The code in write_entry() needs to be refactored
224          * to allow us to feed a <buffer, size, mode> instead of a cache
225          * entry.  Such a refactoring would help merge_recursive as well
226          * (it also writes the merge result to the object database even
227          * when it may contain conflicts).
228          */
229         if (write_sha1_file(result_buf.ptr, result_buf.size,
230                             blob_type, oid.hash))
231                 die(_("Unable to add merge result for '%s'"), path);
232         free(result_buf.ptr);
233         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
234         if (!ce)
235                 die(_("make_cache_entry failed for path '%s'"), path);
236         status = checkout_entry(ce, state, NULL);
237         free(ce);
238         return status;
239 }
240
241 static int checkout_paths(const struct checkout_opts *opts,
242                           const char *revision)
243 {
244         int pos;
245         struct checkout state = CHECKOUT_INIT;
246         static char *ps_matched;
247         struct object_id rev;
248         struct commit *head;
249         int errs = 0;
250         struct lock_file lock_file = LOCK_INIT;
251
252         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
253                 die(_("'%s' cannot be used with updating paths"), "--track");
254
255         if (opts->new_branch_log)
256                 die(_("'%s' cannot be used with updating paths"), "-l");
257
258         if (opts->force && opts->patch_mode)
259                 die(_("'%s' cannot be used with updating paths"), "-f");
260
261         if (opts->force_detach)
262                 die(_("'%s' cannot be used with updating paths"), "--detach");
263
264         if (opts->merge && opts->patch_mode)
265                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
266
267         if (opts->force && opts->merge)
268                 die(_("'%s' cannot be used with %s"), "-f", "-m");
269
270         if (opts->new_branch)
271                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
272                     opts->new_branch);
273
274         if (opts->patch_mode)
275                 return run_add_interactive(revision, "--patch=checkout",
276                                            &opts->pathspec);
277
278         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
279         if (read_cache_preload(&opts->pathspec) < 0)
280                 return error(_("index file corrupt"));
281
282         if (opts->source_tree)
283                 read_tree_some(opts->source_tree, &opts->pathspec);
284
285         ps_matched = xcalloc(opts->pathspec.nr, 1);
286
287         /*
288          * Make sure all pathspecs participated in locating the paths
289          * to be checked out.
290          */
291         for (pos = 0; pos < active_nr; pos++) {
292                 struct cache_entry *ce = active_cache[pos];
293                 ce->ce_flags &= ~CE_MATCHED;
294                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
295                         continue;
296                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
297                         /*
298                          * "git checkout tree-ish -- path", but this entry
299                          * is in the original index; it will not be checked
300                          * out to the working tree and it does not matter
301                          * if pathspec matched this entry.  We will not do
302                          * anything to this entry at all.
303                          */
304                         continue;
305                 /*
306                  * Either this entry came from the tree-ish we are
307                  * checking the paths out of, or we are checking out
308                  * of the index.
309                  *
310                  * If it comes from the tree-ish, we already know it
311                  * matches the pathspec and could just stamp
312                  * CE_MATCHED to it from update_some(). But we still
313                  * need ps_matched and read_tree_recursive (and
314                  * eventually tree_entry_interesting) cannot fill
315                  * ps_matched yet. Once it can, we can avoid calling
316                  * match_pathspec() for _all_ entries when
317                  * opts->source_tree != NULL.
318                  */
319                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
320                         ce->ce_flags |= CE_MATCHED;
321         }
322
323         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
324                 free(ps_matched);
325                 return 1;
326         }
327         free(ps_matched);
328
329         /* "checkout -m path" to recreate conflicted state */
330         if (opts->merge)
331                 unmerge_marked_index(&the_index);
332
333         /* Any unmerged paths? */
334         for (pos = 0; pos < active_nr; pos++) {
335                 const struct cache_entry *ce = active_cache[pos];
336                 if (ce->ce_flags & CE_MATCHED) {
337                         if (!ce_stage(ce))
338                                 continue;
339                         if (opts->force) {
340                                 warning(_("path '%s' is unmerged"), ce->name);
341                         } else if (opts->writeout_stage) {
342                                 errs |= check_stage(opts->writeout_stage, ce, pos);
343                         } else if (opts->merge) {
344                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
345                         } else {
346                                 errs = 1;
347                                 error(_("path '%s' is unmerged"), ce->name);
348                         }
349                         pos = skip_same_name(ce, pos) - 1;
350                 }
351         }
352         if (errs)
353                 return 1;
354
355         /* Now we are committed to check them out */
356         state.force = 1;
357         state.refresh_cache = 1;
358         state.istate = &the_index;
359
360         enable_delayed_checkout(&state);
361         for (pos = 0; pos < active_nr; pos++) {
362                 struct cache_entry *ce = active_cache[pos];
363                 if (ce->ce_flags & CE_MATCHED) {
364                         if (!ce_stage(ce)) {
365                                 errs |= checkout_entry(ce, &state, NULL);
366                                 continue;
367                         }
368                         if (opts->writeout_stage)
369                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
370                         else if (opts->merge)
371                                 errs |= checkout_merged(pos, &state);
372                         pos = skip_same_name(ce, pos) - 1;
373                 }
374         }
375         errs |= finish_delayed_checkout(&state);
376
377         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
378                 die(_("unable to write new index file"));
379
380         read_ref_full("HEAD", 0, &rev, NULL);
381         head = lookup_commit_reference_gently(&rev, 1);
382
383         errs |= post_checkout_hook(head, head, 0);
384         return errs;
385 }
386
387 static void show_local_changes(struct object *head,
388                                const struct diff_options *opts)
389 {
390         struct rev_info rev;
391         /* I think we want full paths, even if we're in a subdirectory. */
392         init_revisions(&rev, NULL);
393         rev.diffopt.flags = opts->flags;
394         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
395         diff_setup_done(&rev.diffopt);
396         add_pending_object(&rev, head, NULL);
397         run_diff_index(&rev, 0);
398 }
399
400 static void describe_detached_head(const char *msg, struct commit *commit)
401 {
402         struct strbuf sb = STRBUF_INIT;
403         if (!parse_commit(commit))
404                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
405         fprintf(stderr, "%s %s... %s\n", msg,
406                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
407         strbuf_release(&sb);
408 }
409
410 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
411                       int worktree, int *writeout_error)
412 {
413         struct unpack_trees_options opts;
414         struct tree_desc tree_desc;
415
416         memset(&opts, 0, sizeof(opts));
417         opts.head_idx = -1;
418         opts.update = worktree;
419         opts.skip_unmerged = !worktree;
420         opts.reset = 1;
421         opts.merge = 1;
422         opts.fn = oneway_merge;
423         opts.verbose_update = o->show_progress;
424         opts.src_index = &the_index;
425         opts.dst_index = &the_index;
426         parse_tree(tree);
427         init_tree_desc(&tree_desc, tree->buffer, tree->size);
428         switch (unpack_trees(1, &tree_desc, &opts)) {
429         case -2:
430                 *writeout_error = 1;
431                 /*
432                  * We return 0 nevertheless, as the index is all right
433                  * and more importantly we have made best efforts to
434                  * update paths in the work tree, and we cannot revert
435                  * them.
436                  */
437                 /* fallthrough */
438         case 0:
439                 return 0;
440         default:
441                 return 128;
442         }
443 }
444
445 struct branch_info {
446         const char *name; /* The short name used */
447         const char *path; /* The full name of a real branch */
448         struct commit *commit; /* The named commit */
449         /*
450          * if not null the branch is detached because it's already
451          * checked out in this checkout
452          */
453         char *checkout;
454 };
455
456 static void setup_branch_path(struct branch_info *branch)
457 {
458         struct strbuf buf = STRBUF_INIT;
459
460         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
461         if (strcmp(buf.buf, branch->name))
462                 branch->name = xstrdup(buf.buf);
463         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
464         branch->path = strbuf_detach(&buf, NULL);
465 }
466
467 static int merge_working_tree(const struct checkout_opts *opts,
468                               struct branch_info *old,
469                               struct branch_info *new,
470                               int *writeout_error)
471 {
472         int ret;
473         struct lock_file lock_file = LOCK_INIT;
474
475         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
476         if (read_cache_preload(NULL) < 0)
477                 return error(_("index file corrupt"));
478
479         resolve_undo_clear();
480         if (opts->force) {
481                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
482                 if (ret)
483                         return ret;
484         } else {
485                 struct tree_desc trees[2];
486                 struct tree *tree;
487                 struct unpack_trees_options topts;
488
489                 memset(&topts, 0, sizeof(topts));
490                 topts.head_idx = -1;
491                 topts.src_index = &the_index;
492                 topts.dst_index = &the_index;
493
494                 setup_unpack_trees_porcelain(&topts, "checkout");
495
496                 refresh_cache(REFRESH_QUIET);
497
498                 if (unmerged_cache()) {
499                         error(_("you need to resolve your current index first"));
500                         return 1;
501                 }
502
503                 /* 2-way merge to the new branch */
504                 topts.initial_checkout = is_cache_unborn();
505                 topts.update = 1;
506                 topts.merge = 1;
507                 topts.gently = opts->merge && old->commit;
508                 topts.verbose_update = opts->show_progress;
509                 topts.fn = twoway_merge;
510                 if (opts->overwrite_ignore) {
511                         topts.dir = xcalloc(1, sizeof(*topts.dir));
512                         topts.dir->flags |= DIR_SHOW_IGNORED;
513                         setup_standard_excludes(topts.dir);
514                 }
515                 tree = parse_tree_indirect(old->commit ?
516                                            &old->commit->object.oid :
517                                            &empty_tree_oid);
518                 init_tree_desc(&trees[0], tree->buffer, tree->size);
519                 tree = parse_tree_indirect(&new->commit->object.oid);
520                 init_tree_desc(&trees[1], tree->buffer, tree->size);
521
522                 ret = unpack_trees(2, trees, &topts);
523                 if (ret == -1) {
524                         /*
525                          * Unpack couldn't do a trivial merge; either
526                          * give up or do a real merge, depending on
527                          * whether the merge flag was used.
528                          */
529                         struct tree *result;
530                         struct tree *work;
531                         struct merge_options o;
532                         if (!opts->merge)
533                                 return 1;
534
535                         /*
536                          * Without old->commit, the below is the same as
537                          * the two-tree unpack we already tried and failed.
538                          */
539                         if (!old->commit)
540                                 return 1;
541
542                         /* Do more real merge */
543
544                         /*
545                          * We update the index fully, then write the
546                          * tree from the index, then merge the new
547                          * branch with the current tree, with the old
548                          * branch as the base. Then we reset the index
549                          * (but not the working tree) to the new
550                          * branch, leaving the working tree as the
551                          * merged version, but skipping unmerged
552                          * entries in the index.
553                          */
554
555                         add_files_to_cache(NULL, NULL, 0);
556                         /*
557                          * NEEDSWORK: carrying over local changes
558                          * when branches have different end-of-line
559                          * normalization (or clean+smudge rules) is
560                          * a pain; plumb in an option to set
561                          * o.renormalize?
562                          */
563                         init_merge_options(&o);
564                         o.verbosity = 0;
565                         work = write_tree_from_memory(&o);
566
567                         ret = reset_tree(new->commit->tree, opts, 1,
568                                          writeout_error);
569                         if (ret)
570                                 return ret;
571                         o.ancestor = old->name;
572                         o.branch1 = new->name;
573                         o.branch2 = "local";
574                         ret = merge_trees(&o, new->commit->tree, work,
575                                 old->commit->tree, &result);
576                         if (ret < 0)
577                                 exit(128);
578                         ret = reset_tree(new->commit->tree, opts, 0,
579                                          writeout_error);
580                         strbuf_release(&o.obuf);
581                         if (ret)
582                                 return ret;
583                 }
584         }
585
586         if (!active_cache_tree)
587                 active_cache_tree = cache_tree();
588
589         if (!cache_tree_fully_valid(active_cache_tree))
590                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
591
592         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
593                 die(_("unable to write new index file"));
594
595         if (!opts->force && !opts->quiet)
596                 show_local_changes(&new->commit->object, &opts->diff_options);
597
598         return 0;
599 }
600
601 static void report_tracking(struct branch_info *new)
602 {
603         struct strbuf sb = STRBUF_INIT;
604         struct branch *branch = branch_get(new->name);
605
606         if (!format_tracking_info(branch, &sb))
607                 return;
608         fputs(sb.buf, stdout);
609         strbuf_release(&sb);
610 }
611
612 static void update_refs_for_switch(const struct checkout_opts *opts,
613                                    struct branch_info *old,
614                                    struct branch_info *new)
615 {
616         struct strbuf msg = STRBUF_INIT;
617         const char *old_desc, *reflog_msg;
618         if (opts->new_branch) {
619                 if (opts->new_orphan_branch) {
620                         char *refname;
621
622                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
623                         if (opts->new_branch_log &&
624                             !should_autocreate_reflog(refname)) {
625                                 int ret;
626                                 struct strbuf err = STRBUF_INIT;
627
628                                 ret = safe_create_reflog(refname, 1, &err);
629                                 if (ret) {
630                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
631                                                 opts->new_orphan_branch, err.buf);
632                                         strbuf_release(&err);
633                                         free(refname);
634                                         return;
635                                 }
636                                 strbuf_release(&err);
637                         }
638                         free(refname);
639                 }
640                 else
641                         create_branch(opts->new_branch, new->name,
642                                       opts->new_branch_force ? 1 : 0,
643                                       opts->new_branch_log,
644                                       opts->new_branch_force ? 1 : 0,
645                                       opts->quiet,
646                                       opts->track);
647                 new->name = opts->new_branch;
648                 setup_branch_path(new);
649         }
650
651         old_desc = old->name;
652         if (!old_desc && old->commit)
653                 old_desc = oid_to_hex(&old->commit->object.oid);
654
655         reflog_msg = getenv("GIT_REFLOG_ACTION");
656         if (!reflog_msg)
657                 strbuf_addf(&msg, "checkout: moving from %s to %s",
658                         old_desc ? old_desc : "(invalid)", new->name);
659         else
660                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
661
662         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
663                 /* Nothing to do. */
664         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
665                 update_ref(msg.buf, "HEAD", &new->commit->object.oid, NULL,
666                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
667                 if (!opts->quiet) {
668                         if (old->path &&
669                             advice_detached_head && !opts->force_detach)
670                                 detach_advice(new->name);
671                         describe_detached_head(_("HEAD is now at"), new->commit);
672                 }
673         } else if (new->path) { /* Switch branches. */
674                 if (create_symref("HEAD", new->path, msg.buf) < 0)
675                         die(_("unable to update HEAD"));
676                 if (!opts->quiet) {
677                         if (old->path && !strcmp(new->path, old->path)) {
678                                 if (opts->new_branch_force)
679                                         fprintf(stderr, _("Reset branch '%s'\n"),
680                                                 new->name);
681                                 else
682                                         fprintf(stderr, _("Already on '%s'\n"),
683                                                 new->name);
684                         } else if (opts->new_branch) {
685                                 if (opts->branch_exists)
686                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
687                                 else
688                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
689                         } else {
690                                 fprintf(stderr, _("Switched to branch '%s'\n"),
691                                         new->name);
692                         }
693                 }
694                 if (old->path && old->name) {
695                         if (!ref_exists(old->path) && reflog_exists(old->path))
696                                 delete_reflog(old->path);
697                 }
698         }
699         remove_branch_state();
700         strbuf_release(&msg);
701         if (!opts->quiet &&
702             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
703                 report_tracking(new);
704 }
705
706 static int add_pending_uninteresting_ref(const char *refname,
707                                          const struct object_id *oid,
708                                          int flags, void *cb_data)
709 {
710         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
711         return 0;
712 }
713
714 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
715 {
716         strbuf_addstr(sb, "  ");
717         strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
718         strbuf_addch(sb, ' ');
719         if (!parse_commit(commit))
720                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
721         strbuf_addch(sb, '\n');
722 }
723
724 #define ORPHAN_CUTOFF 4
725 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
726 {
727         struct commit *c, *last = NULL;
728         struct strbuf sb = STRBUF_INIT;
729         int lost = 0;
730         while ((c = get_revision(revs)) != NULL) {
731                 if (lost < ORPHAN_CUTOFF)
732                         describe_one_orphan(&sb, c);
733                 last = c;
734                 lost++;
735         }
736         if (ORPHAN_CUTOFF < lost) {
737                 int more = lost - ORPHAN_CUTOFF;
738                 if (more == 1)
739                         describe_one_orphan(&sb, last);
740                 else
741                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
742         }
743
744         fprintf(stderr,
745                 Q_(
746                 /* The singular version */
747                 "Warning: you are leaving %d commit behind, "
748                 "not connected to\n"
749                 "any of your branches:\n\n"
750                 "%s\n",
751                 /* The plural version */
752                 "Warning: you are leaving %d commits behind, "
753                 "not connected to\n"
754                 "any of your branches:\n\n"
755                 "%s\n",
756                 /* Give ngettext() the count */
757                 lost),
758                 lost,
759                 sb.buf);
760         strbuf_release(&sb);
761
762         if (advice_detached_head)
763                 fprintf(stderr,
764                         Q_(
765                         /* The singular version */
766                         "If you want to keep it by creating a new branch, "
767                         "this may be a good time\nto do so with:\n\n"
768                         " git branch <new-branch-name> %s\n\n",
769                         /* The plural version */
770                         "If you want to keep them by creating a new branch, "
771                         "this may be a good time\nto do so with:\n\n"
772                         " git branch <new-branch-name> %s\n\n",
773                         /* Give ngettext() the count */
774                         lost),
775                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
776 }
777
778 /*
779  * We are about to leave commit that was at the tip of a detached
780  * HEAD.  If it is not reachable from any ref, this is the last chance
781  * for the user to do so without resorting to reflog.
782  */
783 static void orphaned_commit_warning(struct commit *old, struct commit *new)
784 {
785         struct rev_info revs;
786         struct object *object = &old->object;
787         struct object_array refs;
788
789         init_revisions(&revs, NULL);
790         setup_revisions(0, NULL, &revs, NULL);
791
792         object->flags &= ~UNINTERESTING;
793         add_pending_object(&revs, object, oid_to_hex(&object->oid));
794
795         for_each_ref(add_pending_uninteresting_ref, &revs);
796         add_pending_oid(&revs, "HEAD", &new->object.oid, UNINTERESTING);
797
798         /* Save pending objects, so they can be cleaned up later. */
799         refs = revs.pending;
800         revs.leak_pending = 1;
801
802         /*
803          * prepare_revision_walk (together with .leak_pending = 1) makes us
804          * the sole owner of the list of pending objects.
805          */
806         if (prepare_revision_walk(&revs))
807                 die(_("internal error in revision walk"));
808         if (!(old->object.flags & UNINTERESTING))
809                 suggest_reattach(old, &revs);
810         else
811                 describe_detached_head(_("Previous HEAD position was"), old);
812
813         /* Clean up objects used, as they will be reused. */
814         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
815
816         object_array_clear(&refs);
817 }
818
819 static int switch_branches(const struct checkout_opts *opts,
820                            struct branch_info *new)
821 {
822         int ret = 0;
823         struct branch_info old;
824         void *path_to_free;
825         struct object_id rev;
826         int flag, writeout_error = 0;
827         memset(&old, 0, sizeof(old));
828         old.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
829         if (old.path)
830                 old.commit = lookup_commit_reference_gently(&rev, 1);
831         if (!(flag & REF_ISSYMREF))
832                 old.path = NULL;
833
834         if (old.path)
835                 skip_prefix(old.path, "refs/heads/", &old.name);
836
837         if (!new->name) {
838                 new->name = "HEAD";
839                 new->commit = old.commit;
840                 if (!new->commit)
841                         die(_("You are on a branch yet to be born"));
842                 parse_commit_or_die(new->commit);
843         }
844
845         ret = merge_working_tree(opts, &old, new, &writeout_error);
846         if (ret) {
847                 free(path_to_free);
848                 return ret;
849         }
850
851         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
852                 orphaned_commit_warning(old.commit, new->commit);
853
854         update_refs_for_switch(opts, &old, new);
855
856         ret = post_checkout_hook(old.commit, new->commit, 1);
857         free(path_to_free);
858         return ret || writeout_error;
859 }
860
861 static int git_checkout_config(const char *var, const char *value, void *cb)
862 {
863         if (!strcmp(var, "diff.ignoresubmodules")) {
864                 struct checkout_opts *opts = cb;
865                 handle_ignore_submodules_arg(&opts->diff_options, value);
866                 return 0;
867         }
868
869         if (starts_with(var, "submodule."))
870                 return git_default_submodule_config(var, value, NULL);
871
872         return git_xmerge_config(var, value, NULL);
873 }
874
875 struct tracking_name_data {
876         /* const */ char *src_ref;
877         char *dst_ref;
878         struct object_id *dst_oid;
879         int unique;
880 };
881
882 static int check_tracking_name(struct remote *remote, void *cb_data)
883 {
884         struct tracking_name_data *cb = cb_data;
885         struct refspec query;
886         memset(&query, 0, sizeof(struct refspec));
887         query.src = cb->src_ref;
888         if (remote_find_tracking(remote, &query) ||
889             get_oid(query.dst, cb->dst_oid)) {
890                 free(query.dst);
891                 return 0;
892         }
893         if (cb->dst_ref) {
894                 free(query.dst);
895                 cb->unique = 0;
896                 return 0;
897         }
898         cb->dst_ref = query.dst;
899         return 0;
900 }
901
902 static const char *unique_tracking_name(const char *name, struct object_id *oid)
903 {
904         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
905         cb_data.src_ref = xstrfmt("refs/heads/%s", name);
906         cb_data.dst_oid = oid;
907         for_each_remote(check_tracking_name, &cb_data);
908         free(cb_data.src_ref);
909         if (cb_data.unique)
910                 return cb_data.dst_ref;
911         free(cb_data.dst_ref);
912         return NULL;
913 }
914
915 static int parse_branchname_arg(int argc, const char **argv,
916                                 int dwim_new_local_branch_ok,
917                                 struct branch_info *new,
918                                 struct checkout_opts *opts,
919                                 struct object_id *rev)
920 {
921         struct tree **source_tree = &opts->source_tree;
922         const char **new_branch = &opts->new_branch;
923         int argcount = 0;
924         struct object_id branch_rev;
925         const char *arg;
926         int dash_dash_pos;
927         int has_dash_dash = 0;
928         int i;
929
930         /*
931          * case 1: git checkout <ref> -- [<paths>]
932          *
933          *   <ref> must be a valid tree, everything after the '--' must be
934          *   a path.
935          *
936          * case 2: git checkout -- [<paths>]
937          *
938          *   everything after the '--' must be paths.
939          *
940          * case 3: git checkout <something> [--]
941          *
942          *   (a) If <something> is a commit, that is to
943          *       switch to the branch or detach HEAD at it.  As a special case,
944          *       if <something> is A...B (missing A or B means HEAD but you can
945          *       omit at most one side), and if there is a unique merge base
946          *       between A and B, A...B names that merge base.
947          *
948          *   (b) If <something> is _not_ a commit, either "--" is present
949          *       or <something> is not a path, no -t or -b was given, and
950          *       and there is a tracking branch whose name is <something>
951          *       in one and only one remote, then this is a short-hand to
952          *       fork local <something> from that remote-tracking branch.
953          *
954          *   (c) Otherwise, if "--" is present, treat it like case (1).
955          *
956          *   (d) Otherwise :
957          *       - if it's a reference, treat it like case (1)
958          *       - else if it's a path, treat it like case (2)
959          *       - else: fail.
960          *
961          * case 4: git checkout <something> <paths>
962          *
963          *   The first argument must not be ambiguous.
964          *   - If it's *only* a reference, treat it like case (1).
965          *   - If it's only a path, treat it like case (2).
966          *   - else: fail.
967          *
968          */
969         if (!argc)
970                 return 0;
971
972         arg = argv[0];
973         dash_dash_pos = -1;
974         for (i = 0; i < argc; i++) {
975                 if (!strcmp(argv[i], "--")) {
976                         dash_dash_pos = i;
977                         break;
978                 }
979         }
980         if (dash_dash_pos == 0)
981                 return 1; /* case (2) */
982         else if (dash_dash_pos == 1)
983                 has_dash_dash = 1; /* case (3) or (1) */
984         else if (dash_dash_pos >= 2)
985                 die(_("only one reference expected, %d given."), dash_dash_pos);
986
987         if (!strcmp(arg, "-"))
988                 arg = "@{-1}";
989
990         if (get_oid_mb(arg, rev)) {
991                 /*
992                  * Either case (3) or (4), with <something> not being
993                  * a commit, or an attempt to use case (1) with an
994                  * invalid ref.
995                  *
996                  * It's likely an error, but we need to find out if
997                  * we should auto-create the branch, case (3).(b).
998                  */
999                 int recover_with_dwim = dwim_new_local_branch_ok;
1000
1001                 if (!has_dash_dash &&
1002                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
1003                         recover_with_dwim = 0;
1004                 /*
1005                  * Accept "git checkout foo" and "git checkout foo --"
1006                  * as candidates for dwim.
1007                  */
1008                 if (!(argc == 1 && !has_dash_dash) &&
1009                     !(argc == 2 && has_dash_dash))
1010                         recover_with_dwim = 0;
1011
1012                 if (recover_with_dwim) {
1013                         const char *remote = unique_tracking_name(arg, rev);
1014                         if (remote) {
1015                                 *new_branch = arg;
1016                                 arg = remote;
1017                                 /* DWIMmed to create local branch, case (3).(b) */
1018                         } else {
1019                                 recover_with_dwim = 0;
1020                         }
1021                 }
1022
1023                 if (!recover_with_dwim) {
1024                         if (has_dash_dash)
1025                                 die(_("invalid reference: %s"), arg);
1026                         return argcount;
1027                 }
1028         }
1029
1030         /* we can't end up being in (2) anymore, eat the argument */
1031         argcount++;
1032         argv++;
1033         argc--;
1034
1035         new->name = arg;
1036         setup_branch_path(new);
1037
1038         if (!check_refname_format(new->path, 0) &&
1039             !read_ref(new->path, &branch_rev))
1040                 oidcpy(rev, &branch_rev);
1041         else
1042                 new->path = NULL; /* not an existing branch */
1043
1044         new->commit = lookup_commit_reference_gently(rev, 1);
1045         if (!new->commit) {
1046                 /* not a commit */
1047                 *source_tree = parse_tree_indirect(rev);
1048         } else {
1049                 parse_commit_or_die(new->commit);
1050                 *source_tree = new->commit->tree;
1051         }
1052
1053         if (!*source_tree)                   /* case (1): want a tree */
1054                 die(_("reference is not a tree: %s"), arg);
1055         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1056                 /*
1057                  * Do not complain the most common case
1058                  *      git checkout branch
1059                  * even if there happen to be a file called 'branch';
1060                  * it would be extremely annoying.
1061                  */
1062                 if (argc)
1063                         verify_non_filename(opts->prefix, arg);
1064         } else {
1065                 argcount++;
1066                 argv++;
1067                 argc--;
1068         }
1069
1070         return argcount;
1071 }
1072
1073 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1074 {
1075         int status;
1076         struct strbuf branch_ref = STRBUF_INIT;
1077
1078         if (!opts->new_branch)
1079                 die(_("You are on a branch yet to be born"));
1080         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1081         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1082         strbuf_release(&branch_ref);
1083         if (!opts->quiet)
1084                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1085                         opts->new_branch);
1086         return status;
1087 }
1088
1089 static int checkout_branch(struct checkout_opts *opts,
1090                            struct branch_info *new)
1091 {
1092         if (opts->pathspec.nr)
1093                 die(_("paths cannot be used with switching branches"));
1094
1095         if (opts->patch_mode)
1096                 die(_("'%s' cannot be used with switching branches"),
1097                     "--patch");
1098
1099         if (opts->writeout_stage)
1100                 die(_("'%s' cannot be used with switching branches"),
1101                     "--ours/--theirs");
1102
1103         if (opts->force && opts->merge)
1104                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1105
1106         if (opts->force_detach && opts->new_branch)
1107                 die(_("'%s' cannot be used with '%s'"),
1108                     "--detach", "-b/-B/--orphan");
1109
1110         if (opts->new_orphan_branch) {
1111                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1112                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1113         } else if (opts->force_detach) {
1114                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1115                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1116         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1117                 opts->track = git_branch_track;
1118
1119         if (new->name && !new->commit)
1120                 die(_("Cannot switch branch to a non-commit '%s'"),
1121                     new->name);
1122
1123         if (new->path && !opts->force_detach && !opts->new_branch &&
1124             !opts->ignore_other_worktrees) {
1125                 int flag;
1126                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1127                 if (head_ref &&
1128                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1129                         die_if_checked_out(new->path, 1);
1130                 free(head_ref);
1131         }
1132
1133         if (!new->commit && opts->new_branch) {
1134                 struct object_id rev;
1135                 int flag;
1136
1137                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1138                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1139                         return switch_unborn_to_new_branch(opts);
1140         }
1141         return switch_branches(opts, new);
1142 }
1143
1144 int cmd_checkout(int argc, const char **argv, const char *prefix)
1145 {
1146         struct checkout_opts opts;
1147         struct branch_info new;
1148         char *conflict_style = NULL;
1149         int dwim_new_local_branch = 1;
1150         struct option options[] = {
1151                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1152                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1153                            N_("create and checkout a new branch")),
1154                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1155                            N_("create/reset and checkout a branch")),
1156                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1157                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1158                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1159                         BRANCH_TRACK_EXPLICIT),
1160                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1161                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1162                             2),
1163                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1164                             3),
1165                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1166                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1167                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1168                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1169                            N_("conflict style (merge or diff3)")),
1170                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1171                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1172                          N_("do not limit pathspecs to sparse entries only")),
1173                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1174                                 N_("second guess 'git checkout <no-such-branch>'")),
1175                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1176                          N_("do not check if another worktree is holding the given ref")),
1177                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1178                             "checkout", "control recursive updating of submodules",
1179                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1180                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1181                 OPT_END(),
1182         };
1183
1184         memset(&opts, 0, sizeof(opts));
1185         memset(&new, 0, sizeof(new));
1186         opts.overwrite_ignore = 1;
1187         opts.prefix = prefix;
1188         opts.show_progress = -1;
1189
1190         git_config(git_checkout_config, &opts);
1191
1192         opts.track = BRANCH_TRACK_UNSPECIFIED;
1193
1194         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1195                              PARSE_OPT_KEEP_DASHDASH);
1196
1197         if (opts.show_progress < 0) {
1198                 if (opts.quiet)
1199                         opts.show_progress = 0;
1200                 else
1201                         opts.show_progress = isatty(2);
1202         }
1203
1204         if (conflict_style) {
1205                 opts.merge = 1; /* implied */
1206                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1207         }
1208
1209         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1210                 die(_("-b, -B and --orphan are mutually exclusive"));
1211
1212         /*
1213          * From here on, new_branch will contain the branch to be checked out,
1214          * and new_branch_force and new_orphan_branch will tell us which one of
1215          * -b/-B/--orphan is being used.
1216          */
1217         if (opts.new_branch_force)
1218                 opts.new_branch = opts.new_branch_force;
1219
1220         if (opts.new_orphan_branch)
1221                 opts.new_branch = opts.new_orphan_branch;
1222
1223         /* --track without -b/-B/--orphan should DWIM */
1224         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1225                 const char *argv0 = argv[0];
1226                 if (!argc || !strcmp(argv0, "--"))
1227                         die (_("--track needs a branch name"));
1228                 skip_prefix(argv0, "refs/", &argv0);
1229                 skip_prefix(argv0, "remotes/", &argv0);
1230                 argv0 = strchr(argv0, '/');
1231                 if (!argv0 || !argv0[1])
1232                         die (_("Missing branch name; try -b"));
1233                 opts.new_branch = argv0 + 1;
1234         }
1235
1236         /*
1237          * Extract branch name from command line arguments, so
1238          * all that is left is pathspecs.
1239          *
1240          * Handle
1241          *
1242          *  1) git checkout <tree> -- [<paths>]
1243          *  2) git checkout -- [<paths>]
1244          *  3) git checkout <something> [<paths>]
1245          *
1246          * including "last branch" syntax and DWIM-ery for names of
1247          * remote branches, erroring out for invalid or ambiguous cases.
1248          */
1249         if (argc) {
1250                 struct object_id rev;
1251                 int dwim_ok =
1252                         !opts.patch_mode &&
1253                         dwim_new_local_branch &&
1254                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1255                         !opts.new_branch;
1256                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1257                                              &new, &opts, &rev);
1258                 argv += n;
1259                 argc -= n;
1260         }
1261
1262         if (argc) {
1263                 parse_pathspec(&opts.pathspec, 0,
1264                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1265                                prefix, argv);
1266
1267                 if (!opts.pathspec.nr)
1268                         die(_("invalid path specification"));
1269
1270                 /*
1271                  * Try to give more helpful suggestion.
1272                  * new_branch && argc > 1 will be caught later.
1273                  */
1274                 if (opts.new_branch && argc == 1)
1275                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1276                                 argv[0], opts.new_branch);
1277
1278                 if (opts.force_detach)
1279                         die(_("git checkout: --detach does not take a path argument '%s'"),
1280                             argv[0]);
1281
1282                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1283                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1284                               "checking out of the index."));
1285         }
1286
1287         if (opts.new_branch) {
1288                 struct strbuf buf = STRBUF_INIT;
1289
1290                 if (opts.new_branch_force)
1291                         opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1292                 else
1293                         opts.branch_exists =
1294                                 validate_new_branchname(opts.new_branch, &buf, 0);
1295                 strbuf_release(&buf);
1296         }
1297
1298         UNLEAK(opts);
1299         if (opts.patch_mode || opts.pathspec.nr)
1300                 return checkout_paths(&opts, new.name);
1301         else
1302                 return checkout_branch(&opts, &new);
1303 }