format-patch: allow --interdiff to apply to a lone-patch
[git] / builtin / checkout.c
1 #include "builtin.h"
2 #include "config.h"
3 #include "checkout.h"
4 #include "lockfile.h"
5 #include "parse-options.h"
6 #include "refs.h"
7 #include "object-store.h"
8 #include "commit.h"
9 #include "tree.h"
10 #include "tree-walk.h"
11 #include "cache-tree.h"
12 #include "unpack-trees.h"
13 #include "dir.h"
14 #include "run-command.h"
15 #include "merge-recursive.h"
16 #include "branch.h"
17 #include "diff.h"
18 #include "revision.h"
19 #include "remote.h"
20 #include "blob.h"
21 #include "xdiff-interface.h"
22 #include "ll-merge.h"
23 #include "resolve-undo.h"
24 #include "submodule-config.h"
25 #include "submodule.h"
26
27 static const char * const checkout_usage[] = {
28         N_("git checkout [<options>] <branch>"),
29         N_("git checkout [<options>] [<branch>] -- <file>..."),
30         NULL,
31 };
32
33 struct checkout_opts {
34         int patch_mode;
35         int quiet;
36         int merge;
37         int force;
38         int force_detach;
39         int writeout_stage;
40         int overwrite_ignore;
41         int ignore_skipworktree;
42         int ignore_other_worktrees;
43         int show_progress;
44
45         const char *new_branch;
46         const char *new_branch_force;
47         const char *new_orphan_branch;
48         int new_branch_log;
49         enum branch_track track;
50         struct diff_options diff_options;
51
52         int branch_exists;
53         const char *prefix;
54         struct pathspec pathspec;
55         struct tree *source_tree;
56 };
57
58 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
59                               int changed)
60 {
61         return run_hook_le(NULL, "post-checkout",
62                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
63                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
64                            changed ? "1" : "0", NULL);
65         /* "new_commit" can be NULL when checking out from the index before
66            a commit exists. */
67
68 }
69
70 static int update_some(const struct object_id *oid, struct strbuf *base,
71                 const char *pathname, unsigned mode, int stage, void *context)
72 {
73         int len;
74         struct cache_entry *ce;
75         int pos;
76
77         if (S_ISDIR(mode))
78                 return READ_TREE_RECURSIVE;
79
80         len = base->len + strlen(pathname);
81         ce = xcalloc(1, cache_entry_size(len));
82         oidcpy(&ce->oid, oid);
83         memcpy(ce->name, base->buf, base->len);
84         memcpy(ce->name + base->len, pathname, len - base->len);
85         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
86         ce->ce_namelen = len;
87         ce->ce_mode = create_ce_mode(mode);
88
89         /*
90          * If the entry is the same as the current index, we can leave the old
91          * entry in place. Whether it is UPTODATE or not, checkout_entry will
92          * do the right thing.
93          */
94         pos = cache_name_pos(ce->name, ce->ce_namelen);
95         if (pos >= 0) {
96                 struct cache_entry *old = active_cache[pos];
97                 if (ce->ce_mode == old->ce_mode &&
98                     !oidcmp(&ce->oid, &old->oid)) {
99                         old->ce_flags |= CE_UPDATE;
100                         free(ce);
101                         return 0;
102                 }
103         }
104
105         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
106         return 0;
107 }
108
109 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
110 {
111         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
112
113         /* update the index with the given tree's info
114          * for all args, expanding wildcards, and exit
115          * with any non-zero return code.
116          */
117         return 0;
118 }
119
120 static int skip_same_name(const struct cache_entry *ce, int pos)
121 {
122         while (++pos < active_nr &&
123                !strcmp(active_cache[pos]->name, ce->name))
124                 ; /* skip */
125         return pos;
126 }
127
128 static int check_stage(int stage, const struct cache_entry *ce, int pos)
129 {
130         while (pos < active_nr &&
131                !strcmp(active_cache[pos]->name, ce->name)) {
132                 if (ce_stage(active_cache[pos]) == stage)
133                         return 0;
134                 pos++;
135         }
136         if (stage == 2)
137                 return error(_("path '%s' does not have our version"), ce->name);
138         else
139                 return error(_("path '%s' does not have their version"), ce->name);
140 }
141
142 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
143 {
144         unsigned seen = 0;
145         const char *name = ce->name;
146
147         while (pos < active_nr) {
148                 ce = active_cache[pos];
149                 if (strcmp(name, ce->name))
150                         break;
151                 seen |= (1 << ce_stage(ce));
152                 pos++;
153         }
154         if ((stages & seen) != stages)
155                 return error(_("path '%s' does not have all necessary versions"),
156                              name);
157         return 0;
158 }
159
160 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
161                           const struct checkout *state)
162 {
163         while (pos < active_nr &&
164                !strcmp(active_cache[pos]->name, ce->name)) {
165                 if (ce_stage(active_cache[pos]) == stage)
166                         return checkout_entry(active_cache[pos], state, NULL);
167                 pos++;
168         }
169         if (stage == 2)
170                 return error(_("path '%s' does not have our version"), ce->name);
171         else
172                 return error(_("path '%s' does not have their version"), ce->name);
173 }
174
175 static int checkout_merged(int pos, const struct checkout *state)
176 {
177         struct cache_entry *ce = active_cache[pos];
178         const char *path = ce->name;
179         mmfile_t ancestor, ours, theirs;
180         int status;
181         struct object_id oid;
182         mmbuffer_t result_buf;
183         struct object_id threeway[3];
184         unsigned mode = 0;
185
186         memset(threeway, 0, sizeof(threeway));
187         while (pos < active_nr) {
188                 int stage;
189                 stage = ce_stage(ce);
190                 if (!stage || strcmp(path, ce->name))
191                         break;
192                 oidcpy(&threeway[stage - 1], &ce->oid);
193                 if (stage == 2)
194                         mode = create_ce_mode(ce->ce_mode);
195                 pos++;
196                 ce = active_cache[pos];
197         }
198         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
199                 return error(_("path '%s' does not have necessary versions"), path);
200
201         read_mmblob(&ancestor, &threeway[0]);
202         read_mmblob(&ours, &threeway[1]);
203         read_mmblob(&theirs, &threeway[2]);
204
205         /*
206          * NEEDSWORK: re-create conflicts from merges with
207          * merge.renormalize set, too
208          */
209         status = ll_merge(&result_buf, path, &ancestor, "base",
210                           &ours, "ours", &theirs, "theirs", NULL);
211         free(ancestor.ptr);
212         free(ours.ptr);
213         free(theirs.ptr);
214         if (status < 0 || !result_buf.ptr) {
215                 free(result_buf.ptr);
216                 return error(_("path '%s': cannot merge"), path);
217         }
218
219         /*
220          * NEEDSWORK:
221          * There is absolutely no reason to write this as a blob object
222          * and create a phony cache entry.  This hack is primarily to get
223          * to the write_entry() machinery that massages the contents to
224          * work-tree format and writes out which only allows it for a
225          * cache entry.  The code in write_entry() needs to be refactored
226          * to allow us to feed a <buffer, size, mode> instead of a cache
227          * entry.  Such a refactoring would help merge_recursive as well
228          * (it also writes the merge result to the object database even
229          * when it may contain conflicts).
230          */
231         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
232                 die(_("Unable to add merge result for '%s'"), path);
233         free(result_buf.ptr);
234         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
235         if (!ce)
236                 die(_("make_cache_entry failed for path '%s'"), path);
237         status = checkout_entry(ce, state, NULL);
238         free(ce);
239         return status;
240 }
241
242 static int checkout_paths(const struct checkout_opts *opts,
243                           const char *revision)
244 {
245         int pos;
246         struct checkout state = CHECKOUT_INIT;
247         static char *ps_matched;
248         struct object_id rev;
249         struct commit *head;
250         int errs = 0;
251         struct lock_file lock_file = LOCK_INIT;
252
253         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
254                 die(_("'%s' cannot be used with updating paths"), "--track");
255
256         if (opts->new_branch_log)
257                 die(_("'%s' cannot be used with updating paths"), "-l");
258
259         if (opts->force && opts->patch_mode)
260                 die(_("'%s' cannot be used with updating paths"), "-f");
261
262         if (opts->force_detach)
263                 die(_("'%s' cannot be used with updating paths"), "--detach");
264
265         if (opts->merge && opts->patch_mode)
266                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
267
268         if (opts->force && opts->merge)
269                 die(_("'%s' cannot be used with %s"), "-f", "-m");
270
271         if (opts->new_branch)
272                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
273                     opts->new_branch);
274
275         if (opts->patch_mode)
276                 return run_add_interactive(revision, "--patch=checkout",
277                                            &opts->pathspec);
278
279         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
280         if (read_cache_preload(&opts->pathspec) < 0)
281                 return error(_("index file corrupt"));
282
283         if (opts->source_tree)
284                 read_tree_some(opts->source_tree, &opts->pathspec);
285
286         ps_matched = xcalloc(opts->pathspec.nr, 1);
287
288         /*
289          * Make sure all pathspecs participated in locating the paths
290          * to be checked out.
291          */
292         for (pos = 0; pos < active_nr; pos++) {
293                 struct cache_entry *ce = active_cache[pos];
294                 ce->ce_flags &= ~CE_MATCHED;
295                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
296                         continue;
297                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
298                         /*
299                          * "git checkout tree-ish -- path", but this entry
300                          * is in the original index; it will not be checked
301                          * out to the working tree and it does not matter
302                          * if pathspec matched this entry.  We will not do
303                          * anything to this entry at all.
304                          */
305                         continue;
306                 /*
307                  * Either this entry came from the tree-ish we are
308                  * checking the paths out of, or we are checking out
309                  * of the index.
310                  *
311                  * If it comes from the tree-ish, we already know it
312                  * matches the pathspec and could just stamp
313                  * CE_MATCHED to it from update_some(). But we still
314                  * need ps_matched and read_tree_recursive (and
315                  * eventually tree_entry_interesting) cannot fill
316                  * ps_matched yet. Once it can, we can avoid calling
317                  * match_pathspec() for _all_ entries when
318                  * opts->source_tree != NULL.
319                  */
320                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
321                         ce->ce_flags |= CE_MATCHED;
322         }
323
324         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
325                 free(ps_matched);
326                 return 1;
327         }
328         free(ps_matched);
329
330         /* "checkout -m path" to recreate conflicted state */
331         if (opts->merge)
332                 unmerge_marked_index(&the_index);
333
334         /* Any unmerged paths? */
335         for (pos = 0; pos < active_nr; pos++) {
336                 const struct cache_entry *ce = active_cache[pos];
337                 if (ce->ce_flags & CE_MATCHED) {
338                         if (!ce_stage(ce))
339                                 continue;
340                         if (opts->force) {
341                                 warning(_("path '%s' is unmerged"), ce->name);
342                         } else if (opts->writeout_stage) {
343                                 errs |= check_stage(opts->writeout_stage, ce, pos);
344                         } else if (opts->merge) {
345                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
346                         } else {
347                                 errs = 1;
348                                 error(_("path '%s' is unmerged"), ce->name);
349                         }
350                         pos = skip_same_name(ce, pos) - 1;
351                 }
352         }
353         if (errs)
354                 return 1;
355
356         /* Now we are committed to check them out */
357         state.force = 1;
358         state.refresh_cache = 1;
359         state.istate = &the_index;
360
361         enable_delayed_checkout(&state);
362         for (pos = 0; pos < active_nr; pos++) {
363                 struct cache_entry *ce = active_cache[pos];
364                 if (ce->ce_flags & CE_MATCHED) {
365                         if (!ce_stage(ce)) {
366                                 errs |= checkout_entry(ce, &state, NULL);
367                                 continue;
368                         }
369                         if (opts->writeout_stage)
370                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
371                         else if (opts->merge)
372                                 errs |= checkout_merged(pos, &state);
373                         pos = skip_same_name(ce, pos) - 1;
374                 }
375         }
376         errs |= finish_delayed_checkout(&state);
377
378         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
379                 die(_("unable to write new index file"));
380
381         read_ref_full("HEAD", 0, &rev, NULL);
382         head = lookup_commit_reference_gently(&rev, 1);
383
384         errs |= post_checkout_hook(head, head, 0);
385         return errs;
386 }
387
388 static void show_local_changes(struct object *head,
389                                const struct diff_options *opts)
390 {
391         struct rev_info rev;
392         /* I think we want full paths, even if we're in a subdirectory. */
393         init_revisions(&rev, NULL);
394         rev.diffopt.flags = opts->flags;
395         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
396         diff_setup_done(&rev.diffopt);
397         add_pending_object(&rev, head, NULL);
398         run_diff_index(&rev, 0);
399 }
400
401 static void describe_detached_head(const char *msg, struct commit *commit)
402 {
403         struct strbuf sb = STRBUF_INIT;
404
405         if (!parse_commit(commit))
406                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
407         if (print_sha1_ellipsis()) {
408                 fprintf(stderr, "%s %s... %s\n", msg,
409                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
410         } else {
411                 fprintf(stderr, "%s %s %s\n", msg,
412                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
413         }
414         strbuf_release(&sb);
415 }
416
417 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
418                       int worktree, int *writeout_error)
419 {
420         struct unpack_trees_options opts;
421         struct tree_desc tree_desc;
422
423         memset(&opts, 0, sizeof(opts));
424         opts.head_idx = -1;
425         opts.update = worktree;
426         opts.skip_unmerged = !worktree;
427         opts.reset = 1;
428         opts.merge = 1;
429         opts.fn = oneway_merge;
430         opts.verbose_update = o->show_progress;
431         opts.src_index = &the_index;
432         opts.dst_index = &the_index;
433         parse_tree(tree);
434         init_tree_desc(&tree_desc, tree->buffer, tree->size);
435         switch (unpack_trees(1, &tree_desc, &opts)) {
436         case -2:
437                 *writeout_error = 1;
438                 /*
439                  * We return 0 nevertheless, as the index is all right
440                  * and more importantly we have made best efforts to
441                  * update paths in the work tree, and we cannot revert
442                  * them.
443                  */
444                 /* fallthrough */
445         case 0:
446                 return 0;
447         default:
448                 return 128;
449         }
450 }
451
452 struct branch_info {
453         const char *name; /* The short name used */
454         const char *path; /* The full name of a real branch */
455         struct commit *commit; /* The named commit */
456         /*
457          * if not null the branch is detached because it's already
458          * checked out in this checkout
459          */
460         char *checkout;
461 };
462
463 static void setup_branch_path(struct branch_info *branch)
464 {
465         struct strbuf buf = STRBUF_INIT;
466
467         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
468         if (strcmp(buf.buf, branch->name))
469                 branch->name = xstrdup(buf.buf);
470         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
471         branch->path = strbuf_detach(&buf, NULL);
472 }
473
474 static int merge_working_tree(const struct checkout_opts *opts,
475                               struct branch_info *old_branch_info,
476                               struct branch_info *new_branch_info,
477                               int *writeout_error)
478 {
479         int ret;
480         struct lock_file lock_file = LOCK_INIT;
481
482         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
483         if (read_cache_preload(NULL) < 0)
484                 return error(_("index file corrupt"));
485
486         resolve_undo_clear();
487         if (opts->force) {
488                 ret = reset_tree(get_commit_tree(new_branch_info->commit),
489                                  opts, 1, writeout_error);
490                 if (ret)
491                         return ret;
492         } else {
493                 struct tree_desc trees[2];
494                 struct tree *tree;
495                 struct unpack_trees_options topts;
496
497                 memset(&topts, 0, sizeof(topts));
498                 topts.head_idx = -1;
499                 topts.src_index = &the_index;
500                 topts.dst_index = &the_index;
501
502                 setup_unpack_trees_porcelain(&topts, "checkout");
503
504                 refresh_cache(REFRESH_QUIET);
505
506                 if (unmerged_cache()) {
507                         error(_("you need to resolve your current index first"));
508                         return 1;
509                 }
510
511                 /* 2-way merge to the new branch */
512                 topts.initial_checkout = is_cache_unborn();
513                 topts.update = 1;
514                 topts.merge = 1;
515                 topts.gently = opts->merge && old_branch_info->commit;
516                 topts.verbose_update = opts->show_progress;
517                 topts.fn = twoway_merge;
518                 if (opts->overwrite_ignore) {
519                         topts.dir = xcalloc(1, sizeof(*topts.dir));
520                         topts.dir->flags |= DIR_SHOW_IGNORED;
521                         setup_standard_excludes(topts.dir);
522                 }
523                 tree = parse_tree_indirect(old_branch_info->commit ?
524                                            &old_branch_info->commit->object.oid :
525                                            the_hash_algo->empty_tree);
526                 init_tree_desc(&trees[0], tree->buffer, tree->size);
527                 tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
528                 init_tree_desc(&trees[1], tree->buffer, tree->size);
529
530                 ret = unpack_trees(2, trees, &topts);
531                 clear_unpack_trees_porcelain(&topts);
532                 if (ret == -1) {
533                         /*
534                          * Unpack couldn't do a trivial merge; either
535                          * give up or do a real merge, depending on
536                          * whether the merge flag was used.
537                          */
538                         struct tree *result;
539                         struct tree *work;
540                         struct merge_options o;
541                         if (!opts->merge)
542                                 return 1;
543
544                         /*
545                          * Without old_branch_info->commit, the below is the same as
546                          * the two-tree unpack we already tried and failed.
547                          */
548                         if (!old_branch_info->commit)
549                                 return 1;
550
551                         /* Do more real merge */
552
553                         /*
554                          * We update the index fully, then write the
555                          * tree from the index, then merge the new
556                          * branch with the current tree, with the old
557                          * branch as the base. Then we reset the index
558                          * (but not the working tree) to the new
559                          * branch, leaving the working tree as the
560                          * merged version, but skipping unmerged
561                          * entries in the index.
562                          */
563
564                         add_files_to_cache(NULL, NULL, 0);
565                         /*
566                          * NEEDSWORK: carrying over local changes
567                          * when branches have different end-of-line
568                          * normalization (or clean+smudge rules) is
569                          * a pain; plumb in an option to set
570                          * o.renormalize?
571                          */
572                         init_merge_options(&o);
573                         o.verbosity = 0;
574                         work = write_tree_from_memory(&o);
575
576                         ret = reset_tree(get_commit_tree(new_branch_info->commit),
577                                          opts, 1,
578                                          writeout_error);
579                         if (ret)
580                                 return ret;
581                         o.ancestor = old_branch_info->name;
582                         o.branch1 = new_branch_info->name;
583                         o.branch2 = "local";
584                         ret = merge_trees(&o,
585                                           get_commit_tree(new_branch_info->commit),
586                                           work,
587                                           get_commit_tree(old_branch_info->commit),
588                                           &result);
589                         if (ret < 0)
590                                 exit(128);
591                         ret = reset_tree(get_commit_tree(new_branch_info->commit),
592                                          opts, 0,
593                                          writeout_error);
594                         strbuf_release(&o.obuf);
595                         if (ret)
596                                 return ret;
597                 }
598         }
599
600         if (!active_cache_tree)
601                 active_cache_tree = cache_tree();
602
603         if (!cache_tree_fully_valid(active_cache_tree))
604                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
605
606         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
607                 die(_("unable to write new index file"));
608
609         if (!opts->force && !opts->quiet)
610                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
611
612         return 0;
613 }
614
615 static void report_tracking(struct branch_info *new_branch_info)
616 {
617         struct strbuf sb = STRBUF_INIT;
618         struct branch *branch = branch_get(new_branch_info->name);
619
620         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
621                 return;
622         fputs(sb.buf, stdout);
623         strbuf_release(&sb);
624 }
625
626 static void update_refs_for_switch(const struct checkout_opts *opts,
627                                    struct branch_info *old_branch_info,
628                                    struct branch_info *new_branch_info)
629 {
630         struct strbuf msg = STRBUF_INIT;
631         const char *old_desc, *reflog_msg;
632         if (opts->new_branch) {
633                 if (opts->new_orphan_branch) {
634                         char *refname;
635
636                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
637                         if (opts->new_branch_log &&
638                             !should_autocreate_reflog(refname)) {
639                                 int ret;
640                                 struct strbuf err = STRBUF_INIT;
641
642                                 ret = safe_create_reflog(refname, 1, &err);
643                                 if (ret) {
644                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
645                                                 opts->new_orphan_branch, err.buf);
646                                         strbuf_release(&err);
647                                         free(refname);
648                                         return;
649                                 }
650                                 strbuf_release(&err);
651                         }
652                         free(refname);
653                 }
654                 else
655                         create_branch(opts->new_branch, new_branch_info->name,
656                                       opts->new_branch_force ? 1 : 0,
657                                       opts->new_branch_force ? 1 : 0,
658                                       opts->new_branch_log,
659                                       opts->quiet,
660                                       opts->track);
661                 new_branch_info->name = opts->new_branch;
662                 setup_branch_path(new_branch_info);
663         }
664
665         old_desc = old_branch_info->name;
666         if (!old_desc && old_branch_info->commit)
667                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
668
669         reflog_msg = getenv("GIT_REFLOG_ACTION");
670         if (!reflog_msg)
671                 strbuf_addf(&msg, "checkout: moving from %s to %s",
672                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
673         else
674                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
675
676         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
677                 /* Nothing to do. */
678         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
679                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
680                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
681                 if (!opts->quiet) {
682                         if (old_branch_info->path &&
683                             advice_detached_head && !opts->force_detach)
684                                 detach_advice(new_branch_info->name);
685                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
686                 }
687         } else if (new_branch_info->path) {     /* Switch branches. */
688                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
689                         die(_("unable to update HEAD"));
690                 if (!opts->quiet) {
691                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
692                                 if (opts->new_branch_force)
693                                         fprintf(stderr, _("Reset branch '%s'\n"),
694                                                 new_branch_info->name);
695                                 else
696                                         fprintf(stderr, _("Already on '%s'\n"),
697                                                 new_branch_info->name);
698                         } else if (opts->new_branch) {
699                                 if (opts->branch_exists)
700                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
701                                 else
702                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
703                         } else {
704                                 fprintf(stderr, _("Switched to branch '%s'\n"),
705                                         new_branch_info->name);
706                         }
707                 }
708                 if (old_branch_info->path && old_branch_info->name) {
709                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
710                                 delete_reflog(old_branch_info->path);
711                 }
712         }
713         remove_branch_state();
714         strbuf_release(&msg);
715         if (!opts->quiet &&
716             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
717                 report_tracking(new_branch_info);
718 }
719
720 static int add_pending_uninteresting_ref(const char *refname,
721                                          const struct object_id *oid,
722                                          int flags, void *cb_data)
723 {
724         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
725         return 0;
726 }
727
728 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
729 {
730         strbuf_addstr(sb, "  ");
731         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
732         strbuf_addch(sb, ' ');
733         if (!parse_commit(commit))
734                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
735         strbuf_addch(sb, '\n');
736 }
737
738 #define ORPHAN_CUTOFF 4
739 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
740 {
741         struct commit *c, *last = NULL;
742         struct strbuf sb = STRBUF_INIT;
743         int lost = 0;
744         while ((c = get_revision(revs)) != NULL) {
745                 if (lost < ORPHAN_CUTOFF)
746                         describe_one_orphan(&sb, c);
747                 last = c;
748                 lost++;
749         }
750         if (ORPHAN_CUTOFF < lost) {
751                 int more = lost - ORPHAN_CUTOFF;
752                 if (more == 1)
753                         describe_one_orphan(&sb, last);
754                 else
755                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
756         }
757
758         fprintf(stderr,
759                 Q_(
760                 /* The singular version */
761                 "Warning: you are leaving %d commit behind, "
762                 "not connected to\n"
763                 "any of your branches:\n\n"
764                 "%s\n",
765                 /* The plural version */
766                 "Warning: you are leaving %d commits behind, "
767                 "not connected to\n"
768                 "any of your branches:\n\n"
769                 "%s\n",
770                 /* Give ngettext() the count */
771                 lost),
772                 lost,
773                 sb.buf);
774         strbuf_release(&sb);
775
776         if (advice_detached_head)
777                 fprintf(stderr,
778                         Q_(
779                         /* The singular version */
780                         "If you want to keep it by creating a new branch, "
781                         "this may be a good time\nto do so with:\n\n"
782                         " git branch <new-branch-name> %s\n\n",
783                         /* The plural version */
784                         "If you want to keep them by creating a new branch, "
785                         "this may be a good time\nto do so with:\n\n"
786                         " git branch <new-branch-name> %s\n\n",
787                         /* Give ngettext() the count */
788                         lost),
789                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
790 }
791
792 /*
793  * We are about to leave commit that was at the tip of a detached
794  * HEAD.  If it is not reachable from any ref, this is the last chance
795  * for the user to do so without resorting to reflog.
796  */
797 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
798 {
799         struct rev_info revs;
800         struct object *object = &old_commit->object;
801
802         init_revisions(&revs, NULL);
803         setup_revisions(0, NULL, &revs, NULL);
804
805         object->flags &= ~UNINTERESTING;
806         add_pending_object(&revs, object, oid_to_hex(&object->oid));
807
808         for_each_ref(add_pending_uninteresting_ref, &revs);
809         add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
810
811         if (prepare_revision_walk(&revs))
812                 die(_("internal error in revision walk"));
813         if (!(old_commit->object.flags & UNINTERESTING))
814                 suggest_reattach(old_commit, &revs);
815         else
816                 describe_detached_head(_("Previous HEAD position was"), old_commit);
817
818         /* Clean up objects used, as they will be reused. */
819         clear_commit_marks_all(ALL_REV_FLAGS);
820 }
821
822 static int switch_branches(const struct checkout_opts *opts,
823                            struct branch_info *new_branch_info)
824 {
825         int ret = 0;
826         struct branch_info old_branch_info;
827         void *path_to_free;
828         struct object_id rev;
829         int flag, writeout_error = 0;
830         memset(&old_branch_info, 0, sizeof(old_branch_info));
831         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
832         if (old_branch_info.path)
833                 old_branch_info.commit = lookup_commit_reference_gently(&rev, 1);
834         if (!(flag & REF_ISSYMREF))
835                 old_branch_info.path = NULL;
836
837         if (old_branch_info.path)
838                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
839
840         if (!new_branch_info->name) {
841                 new_branch_info->name = "HEAD";
842                 new_branch_info->commit = old_branch_info.commit;
843                 if (!new_branch_info->commit)
844                         die(_("You are on a branch yet to be born"));
845                 parse_commit_or_die(new_branch_info->commit);
846         }
847
848         ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
849         if (ret) {
850                 free(path_to_free);
851                 return ret;
852         }
853
854         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
855                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
856
857         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
858
859         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
860         free(path_to_free);
861         return ret || writeout_error;
862 }
863
864 static int git_checkout_config(const char *var, const char *value, void *cb)
865 {
866         if (!strcmp(var, "diff.ignoresubmodules")) {
867                 struct checkout_opts *opts = cb;
868                 handle_ignore_submodules_arg(&opts->diff_options, value);
869                 return 0;
870         }
871
872         if (starts_with(var, "submodule."))
873                 return git_default_submodule_config(var, value, NULL);
874
875         return git_xmerge_config(var, value, NULL);
876 }
877
878 static int parse_branchname_arg(int argc, const char **argv,
879                                 int dwim_new_local_branch_ok,
880                                 struct branch_info *new_branch_info,
881                                 struct checkout_opts *opts,
882                                 struct object_id *rev)
883 {
884         struct tree **source_tree = &opts->source_tree;
885         const char **new_branch = &opts->new_branch;
886         int argcount = 0;
887         struct object_id branch_rev;
888         const char *arg;
889         int dash_dash_pos;
890         int has_dash_dash = 0;
891         int i;
892
893         /*
894          * case 1: git checkout <ref> -- [<paths>]
895          *
896          *   <ref> must be a valid tree, everything after the '--' must be
897          *   a path.
898          *
899          * case 2: git checkout -- [<paths>]
900          *
901          *   everything after the '--' must be paths.
902          *
903          * case 3: git checkout <something> [--]
904          *
905          *   (a) If <something> is a commit, that is to
906          *       switch to the branch or detach HEAD at it.  As a special case,
907          *       if <something> is A...B (missing A or B means HEAD but you can
908          *       omit at most one side), and if there is a unique merge base
909          *       between A and B, A...B names that merge base.
910          *
911          *   (b) If <something> is _not_ a commit, either "--" is present
912          *       or <something> is not a path, no -t or -b was given, and
913          *       and there is a tracking branch whose name is <something>
914          *       in one and only one remote, then this is a short-hand to
915          *       fork local <something> from that remote-tracking branch.
916          *
917          *   (c) Otherwise, if "--" is present, treat it like case (1).
918          *
919          *   (d) Otherwise :
920          *       - if it's a reference, treat it like case (1)
921          *       - else if it's a path, treat it like case (2)
922          *       - else: fail.
923          *
924          * case 4: git checkout <something> <paths>
925          *
926          *   The first argument must not be ambiguous.
927          *   - If it's *only* a reference, treat it like case (1).
928          *   - If it's only a path, treat it like case (2).
929          *   - else: fail.
930          *
931          */
932         if (!argc)
933                 return 0;
934
935         arg = argv[0];
936         dash_dash_pos = -1;
937         for (i = 0; i < argc; i++) {
938                 if (!strcmp(argv[i], "--")) {
939                         dash_dash_pos = i;
940                         break;
941                 }
942         }
943         if (dash_dash_pos == 0)
944                 return 1; /* case (2) */
945         else if (dash_dash_pos == 1)
946                 has_dash_dash = 1; /* case (3) or (1) */
947         else if (dash_dash_pos >= 2)
948                 die(_("only one reference expected, %d given."), dash_dash_pos);
949
950         if (!strcmp(arg, "-"))
951                 arg = "@{-1}";
952
953         if (get_oid_mb(arg, rev)) {
954                 /*
955                  * Either case (3) or (4), with <something> not being
956                  * a commit, or an attempt to use case (1) with an
957                  * invalid ref.
958                  *
959                  * It's likely an error, but we need to find out if
960                  * we should auto-create the branch, case (3).(b).
961                  */
962                 int recover_with_dwim = dwim_new_local_branch_ok;
963
964                 if (!has_dash_dash &&
965                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
966                         recover_with_dwim = 0;
967                 /*
968                  * Accept "git checkout foo" and "git checkout foo --"
969                  * as candidates for dwim.
970                  */
971                 if (!(argc == 1 && !has_dash_dash) &&
972                     !(argc == 2 && has_dash_dash))
973                         recover_with_dwim = 0;
974
975                 if (recover_with_dwim) {
976                         const char *remote = unique_tracking_name(arg, rev);
977                         if (remote) {
978                                 *new_branch = arg;
979                                 arg = remote;
980                                 /* DWIMmed to create local branch, case (3).(b) */
981                         } else {
982                                 recover_with_dwim = 0;
983                         }
984                 }
985
986                 if (!recover_with_dwim) {
987                         if (has_dash_dash)
988                                 die(_("invalid reference: %s"), arg);
989                         return argcount;
990                 }
991         }
992
993         /* we can't end up being in (2) anymore, eat the argument */
994         argcount++;
995         argv++;
996         argc--;
997
998         new_branch_info->name = arg;
999         setup_branch_path(new_branch_info);
1000
1001         if (!check_refname_format(new_branch_info->path, 0) &&
1002             !read_ref(new_branch_info->path, &branch_rev))
1003                 oidcpy(rev, &branch_rev);
1004         else
1005                 new_branch_info->path = NULL; /* not an existing branch */
1006
1007         new_branch_info->commit = lookup_commit_reference_gently(rev, 1);
1008         if (!new_branch_info->commit) {
1009                 /* not a commit */
1010                 *source_tree = parse_tree_indirect(rev);
1011         } else {
1012                 parse_commit_or_die(new_branch_info->commit);
1013                 *source_tree = get_commit_tree(new_branch_info->commit);
1014         }
1015
1016         if (!*source_tree)                   /* case (1): want a tree */
1017                 die(_("reference is not a tree: %s"), arg);
1018         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1019                 /*
1020                  * Do not complain the most common case
1021                  *      git checkout branch
1022                  * even if there happen to be a file called 'branch';
1023                  * it would be extremely annoying.
1024                  */
1025                 if (argc)
1026                         verify_non_filename(opts->prefix, arg);
1027         } else {
1028                 argcount++;
1029                 argv++;
1030                 argc--;
1031         }
1032
1033         return argcount;
1034 }
1035
1036 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1037 {
1038         int status;
1039         struct strbuf branch_ref = STRBUF_INIT;
1040
1041         if (!opts->new_branch)
1042                 die(_("You are on a branch yet to be born"));
1043         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1044         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1045         strbuf_release(&branch_ref);
1046         if (!opts->quiet)
1047                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1048                         opts->new_branch);
1049         return status;
1050 }
1051
1052 static int checkout_branch(struct checkout_opts *opts,
1053                            struct branch_info *new_branch_info)
1054 {
1055         if (opts->pathspec.nr)
1056                 die(_("paths cannot be used with switching branches"));
1057
1058         if (opts->patch_mode)
1059                 die(_("'%s' cannot be used with switching branches"),
1060                     "--patch");
1061
1062         if (opts->writeout_stage)
1063                 die(_("'%s' cannot be used with switching branches"),
1064                     "--ours/--theirs");
1065
1066         if (opts->force && opts->merge)
1067                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1068
1069         if (opts->force_detach && opts->new_branch)
1070                 die(_("'%s' cannot be used with '%s'"),
1071                     "--detach", "-b/-B/--orphan");
1072
1073         if (opts->new_orphan_branch) {
1074                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1075                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1076         } else if (opts->force_detach) {
1077                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1078                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1079         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1080                 opts->track = git_branch_track;
1081
1082         if (new_branch_info->name && !new_branch_info->commit)
1083                 die(_("Cannot switch branch to a non-commit '%s'"),
1084                     new_branch_info->name);
1085
1086         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1087             !opts->ignore_other_worktrees) {
1088                 int flag;
1089                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1090                 if (head_ref &&
1091                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1092                         die_if_checked_out(new_branch_info->path, 1);
1093                 free(head_ref);
1094         }
1095
1096         if (!new_branch_info->commit && opts->new_branch) {
1097                 struct object_id rev;
1098                 int flag;
1099
1100                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1101                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1102                         return switch_unborn_to_new_branch(opts);
1103         }
1104         return switch_branches(opts, new_branch_info);
1105 }
1106
1107 int cmd_checkout(int argc, const char **argv, const char *prefix)
1108 {
1109         struct checkout_opts opts;
1110         struct branch_info new_branch_info;
1111         char *conflict_style = NULL;
1112         int dwim_new_local_branch = 1;
1113         struct option options[] = {
1114                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1115                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1116                            N_("create and checkout a new branch")),
1117                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1118                            N_("create/reset and checkout a branch")),
1119                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1120                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1121                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1122                         BRANCH_TRACK_EXPLICIT),
1123                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1124                 OPT_SET_INT_F('2', "ours", &opts.writeout_stage,
1125                               N_("checkout our version for unmerged files"),
1126                               2, PARSE_OPT_NONEG),
1127                 OPT_SET_INT_F('3', "theirs", &opts.writeout_stage,
1128                               N_("checkout their version for unmerged files"),
1129                               3, PARSE_OPT_NONEG),
1130                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)"),
1131                            PARSE_OPT_NOCOMPLETE),
1132                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1133                 OPT_BOOL_F(0, "overwrite-ignore", &opts.overwrite_ignore,
1134                            N_("update ignored files (default)"),
1135                            PARSE_OPT_NOCOMPLETE),
1136                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1137                            N_("conflict style (merge or diff3)")),
1138                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1139                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1140                          N_("do not limit pathspecs to sparse entries only")),
1141                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1142                                 N_("second guess 'git checkout <no-such-branch>'")),
1143                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1144                          N_("do not check if another worktree is holding the given ref")),
1145                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1146                             "checkout", "control recursive updating of submodules",
1147                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1148                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1149                 OPT_END(),
1150         };
1151
1152         memset(&opts, 0, sizeof(opts));
1153         memset(&new_branch_info, 0, sizeof(new_branch_info));
1154         opts.overwrite_ignore = 1;
1155         opts.prefix = prefix;
1156         opts.show_progress = -1;
1157
1158         git_config(git_checkout_config, &opts);
1159
1160         opts.track = BRANCH_TRACK_UNSPECIFIED;
1161
1162         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1163                              PARSE_OPT_KEEP_DASHDASH);
1164
1165         if (opts.show_progress < 0) {
1166                 if (opts.quiet)
1167                         opts.show_progress = 0;
1168                 else
1169                         opts.show_progress = isatty(2);
1170         }
1171
1172         if (conflict_style) {
1173                 opts.merge = 1; /* implied */
1174                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1175         }
1176
1177         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1178                 die(_("-b, -B and --orphan are mutually exclusive"));
1179
1180         /*
1181          * From here on, new_branch will contain the branch to be checked out,
1182          * and new_branch_force and new_orphan_branch will tell us which one of
1183          * -b/-B/--orphan is being used.
1184          */
1185         if (opts.new_branch_force)
1186                 opts.new_branch = opts.new_branch_force;
1187
1188         if (opts.new_orphan_branch)
1189                 opts.new_branch = opts.new_orphan_branch;
1190
1191         /* --track without -b/-B/--orphan should DWIM */
1192         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1193                 const char *argv0 = argv[0];
1194                 if (!argc || !strcmp(argv0, "--"))
1195                         die (_("--track needs a branch name"));
1196                 skip_prefix(argv0, "refs/", &argv0);
1197                 skip_prefix(argv0, "remotes/", &argv0);
1198                 argv0 = strchr(argv0, '/');
1199                 if (!argv0 || !argv0[1])
1200                         die (_("Missing branch name; try -b"));
1201                 opts.new_branch = argv0 + 1;
1202         }
1203
1204         /*
1205          * Extract branch name from command line arguments, so
1206          * all that is left is pathspecs.
1207          *
1208          * Handle
1209          *
1210          *  1) git checkout <tree> -- [<paths>]
1211          *  2) git checkout -- [<paths>]
1212          *  3) git checkout <something> [<paths>]
1213          *
1214          * including "last branch" syntax and DWIM-ery for names of
1215          * remote branches, erroring out for invalid or ambiguous cases.
1216          */
1217         if (argc) {
1218                 struct object_id rev;
1219                 int dwim_ok =
1220                         !opts.patch_mode &&
1221                         dwim_new_local_branch &&
1222                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1223                         !opts.new_branch;
1224                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1225                                              &new_branch_info, &opts, &rev);
1226                 argv += n;
1227                 argc -= n;
1228         }
1229
1230         if (argc) {
1231                 parse_pathspec(&opts.pathspec, 0,
1232                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1233                                prefix, argv);
1234
1235                 if (!opts.pathspec.nr)
1236                         die(_("invalid path specification"));
1237
1238                 /*
1239                  * Try to give more helpful suggestion.
1240                  * new_branch && argc > 1 will be caught later.
1241                  */
1242                 if (opts.new_branch && argc == 1)
1243                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1244                                 argv[0], opts.new_branch);
1245
1246                 if (opts.force_detach)
1247                         die(_("git checkout: --detach does not take a path argument '%s'"),
1248                             argv[0]);
1249
1250                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1251                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1252                               "checking out of the index."));
1253         }
1254
1255         if (opts.new_branch) {
1256                 struct strbuf buf = STRBUF_INIT;
1257
1258                 if (opts.new_branch_force)
1259                         opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1260                 else
1261                         opts.branch_exists =
1262                                 validate_new_branchname(opts.new_branch, &buf, 0);
1263                 strbuf_release(&buf);
1264         }
1265
1266         UNLEAK(opts);
1267         if (opts.patch_mode || opts.pathspec.nr)
1268                 return checkout_paths(&opts, new_branch_info.name);
1269         else
1270                 return checkout_branch(&opts, &new_branch_info);
1271 }