Merge branch 'pb/t7502-drop-dup' into maint
[git] / builtin / checkout.c
1 #include "builtin.h"
2 #include "lockfile.h"
3 #include "parse-options.h"
4 #include "refs.h"
5 #include "commit.h"
6 #include "tree.h"
7 #include "tree-walk.h"
8 #include "cache-tree.h"
9 #include "unpack-trees.h"
10 #include "dir.h"
11 #include "run-command.h"
12 #include "merge-recursive.h"
13 #include "branch.h"
14 #include "diff.h"
15 #include "revision.h"
16 #include "remote.h"
17 #include "blob.h"
18 #include "xdiff-interface.h"
19 #include "ll-merge.h"
20 #include "resolve-undo.h"
21 #include "submodule-config.h"
22 #include "submodule.h"
23
24 static const char * const checkout_usage[] = {
25         N_("git checkout [<options>] <branch>"),
26         N_("git checkout [<options>] [<branch>] -- <file>..."),
27         NULL,
28 };
29
30 struct checkout_opts {
31         int patch_mode;
32         int quiet;
33         int merge;
34         int force;
35         int force_detach;
36         int writeout_stage;
37         int overwrite_ignore;
38         int ignore_skipworktree;
39         int ignore_other_worktrees;
40         int show_progress;
41
42         const char *new_branch;
43         const char *new_branch_force;
44         const char *new_orphan_branch;
45         int new_branch_log;
46         enum branch_track track;
47         struct diff_options diff_options;
48
49         int branch_exists;
50         const char *prefix;
51         struct pathspec pathspec;
52         struct tree *source_tree;
53 };
54
55 static int post_checkout_hook(struct commit *old, struct commit *new,
56                               int changed)
57 {
58         return run_hook_le(NULL, "post-checkout",
59                            sha1_to_hex(old ? old->object.oid.hash : null_sha1),
60                            sha1_to_hex(new ? new->object.oid.hash : null_sha1),
61                            changed ? "1" : "0", NULL);
62         /* "new" can be NULL when checking out from the index before
63            a commit exists. */
64
65 }
66
67 static int update_some(const unsigned char *sha1, struct strbuf *base,
68                 const char *pathname, unsigned mode, int stage, void *context)
69 {
70         int len;
71         struct cache_entry *ce;
72         int pos;
73
74         if (S_ISDIR(mode))
75                 return READ_TREE_RECURSIVE;
76
77         len = base->len + strlen(pathname);
78         ce = xcalloc(1, cache_entry_size(len));
79         hashcpy(ce->sha1, sha1);
80         memcpy(ce->name, base->buf, base->len);
81         memcpy(ce->name + base->len, pathname, len - base->len);
82         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
83         ce->ce_namelen = len;
84         ce->ce_mode = create_ce_mode(mode);
85
86         /*
87          * If the entry is the same as the current index, we can leave the old
88          * entry in place. Whether it is UPTODATE or not, checkout_entry will
89          * do the right thing.
90          */
91         pos = cache_name_pos(ce->name, ce->ce_namelen);
92         if (pos >= 0) {
93                 struct cache_entry *old = active_cache[pos];
94                 if (ce->ce_mode == old->ce_mode &&
95                     !hashcmp(ce->sha1, old->sha1)) {
96                         old->ce_flags |= CE_UPDATE;
97                         free(ce);
98                         return 0;
99                 }
100         }
101
102         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
103         return 0;
104 }
105
106 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
107 {
108         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
109
110         /* update the index with the given tree's info
111          * for all args, expanding wildcards, and exit
112          * with any non-zero return code.
113          */
114         return 0;
115 }
116
117 static int skip_same_name(const struct cache_entry *ce, int pos)
118 {
119         while (++pos < active_nr &&
120                !strcmp(active_cache[pos]->name, ce->name))
121                 ; /* skip */
122         return pos;
123 }
124
125 static int check_stage(int stage, const struct cache_entry *ce, int pos)
126 {
127         while (pos < active_nr &&
128                !strcmp(active_cache[pos]->name, ce->name)) {
129                 if (ce_stage(active_cache[pos]) == stage)
130                         return 0;
131                 pos++;
132         }
133         if (stage == 2)
134                 return error(_("path '%s' does not have our version"), ce->name);
135         else
136                 return error(_("path '%s' does not have their version"), ce->name);
137 }
138
139 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
140 {
141         unsigned seen = 0;
142         const char *name = ce->name;
143
144         while (pos < active_nr) {
145                 ce = active_cache[pos];
146                 if (strcmp(name, ce->name))
147                         break;
148                 seen |= (1 << ce_stage(ce));
149                 pos++;
150         }
151         if ((stages & seen) != stages)
152                 return error(_("path '%s' does not have all necessary versions"),
153                              name);
154         return 0;
155 }
156
157 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
158                           struct checkout *state)
159 {
160         while (pos < active_nr &&
161                !strcmp(active_cache[pos]->name, ce->name)) {
162                 if (ce_stage(active_cache[pos]) == stage)
163                         return checkout_entry(active_cache[pos], state, NULL);
164                 pos++;
165         }
166         if (stage == 2)
167                 return error(_("path '%s' does not have our version"), ce->name);
168         else
169                 return error(_("path '%s' does not have their version"), ce->name);
170 }
171
172 static int checkout_merged(int pos, struct checkout *state)
173 {
174         struct cache_entry *ce = active_cache[pos];
175         const char *path = ce->name;
176         mmfile_t ancestor, ours, theirs;
177         int status;
178         unsigned char sha1[20];
179         mmbuffer_t result_buf;
180         unsigned char threeway[3][20];
181         unsigned mode = 0;
182
183         memset(threeway, 0, sizeof(threeway));
184         while (pos < active_nr) {
185                 int stage;
186                 stage = ce_stage(ce);
187                 if (!stage || strcmp(path, ce->name))
188                         break;
189                 hashcpy(threeway[stage - 1], ce->sha1);
190                 if (stage == 2)
191                         mode = create_ce_mode(ce->ce_mode);
192                 pos++;
193                 ce = active_cache[pos];
194         }
195         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
196                 return error(_("path '%s' does not have necessary versions"), path);
197
198         read_mmblob(&ancestor, threeway[0]);
199         read_mmblob(&ours, threeway[1]);
200         read_mmblob(&theirs, threeway[2]);
201
202         /*
203          * NEEDSWORK: re-create conflicts from merges with
204          * merge.renormalize set, too
205          */
206         status = ll_merge(&result_buf, path, &ancestor, "base",
207                           &ours, "ours", &theirs, "theirs", NULL);
208         free(ancestor.ptr);
209         free(ours.ptr);
210         free(theirs.ptr);
211         if (status < 0 || !result_buf.ptr) {
212                 free(result_buf.ptr);
213                 return error(_("path '%s': cannot merge"), path);
214         }
215
216         /*
217          * NEEDSWORK:
218          * There is absolutely no reason to write this as a blob object
219          * and create a phony cache entry just to leak.  This hack is
220          * primarily to get to the write_entry() machinery that massages
221          * the contents to work-tree format and writes out which only
222          * allows it for a cache entry.  The code in write_entry() needs
223          * to be refactored to allow us to feed a <buffer, size, mode>
224          * instead of a cache entry.  Such a refactoring would help
225          * merge_recursive as well (it also writes the merge result to the
226          * object database even when it may contain conflicts).
227          */
228         if (write_sha1_file(result_buf.ptr, result_buf.size,
229                             blob_type, sha1))
230                 die(_("Unable to add merge result for '%s'"), path);
231         ce = make_cache_entry(mode, sha1, path, 2, 0);
232         if (!ce)
233                 die(_("make_cache_entry failed for path '%s'"), path);
234         status = checkout_entry(ce, state, NULL);
235         return status;
236 }
237
238 static int checkout_paths(const struct checkout_opts *opts,
239                           const char *revision)
240 {
241         int pos;
242         struct checkout state;
243         static char *ps_matched;
244         unsigned char rev[20];
245         int flag;
246         struct commit *head;
247         int errs = 0;
248         struct lock_file *lock_file;
249
250         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
251                 die(_("'%s' cannot be used with updating paths"), "--track");
252
253         if (opts->new_branch_log)
254                 die(_("'%s' cannot be used with updating paths"), "-l");
255
256         if (opts->force && opts->patch_mode)
257                 die(_("'%s' cannot be used with updating paths"), "-f");
258
259         if (opts->force_detach)
260                 die(_("'%s' cannot be used with updating paths"), "--detach");
261
262         if (opts->merge && opts->patch_mode)
263                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
264
265         if (opts->force && opts->merge)
266                 die(_("'%s' cannot be used with %s"), "-f", "-m");
267
268         if (opts->new_branch)
269                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
270                     opts->new_branch);
271
272         if (opts->patch_mode)
273                 return run_add_interactive(revision, "--patch=checkout",
274                                            &opts->pathspec);
275
276         lock_file = xcalloc(1, sizeof(struct lock_file));
277
278         hold_locked_index(lock_file, 1);
279         if (read_cache_preload(&opts->pathspec) < 0)
280                 return error(_("corrupt index file"));
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         memset(&state, 0, sizeof(state));
357         state.force = 1;
358         state.refresh_cache = 1;
359         state.istate = &the_index;
360         for (pos = 0; pos < active_nr; pos++) {
361                 struct cache_entry *ce = active_cache[pos];
362                 if (ce->ce_flags & CE_MATCHED) {
363                         if (!ce_stage(ce)) {
364                                 errs |= checkout_entry(ce, &state, NULL);
365                                 continue;
366                         }
367                         if (opts->writeout_stage)
368                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
369                         else if (opts->merge)
370                                 errs |= checkout_merged(pos, &state);
371                         pos = skip_same_name(ce, pos) - 1;
372                 }
373         }
374
375         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
376                 die(_("unable to write new index file"));
377
378         read_ref_full("HEAD", 0, rev, &flag);
379         head = lookup_commit_reference_gently(rev, 1);
380
381         errs |= post_checkout_hook(head, head, 0);
382         return errs;
383 }
384
385 static void show_local_changes(struct object *head,
386                                const struct diff_options *opts)
387 {
388         struct rev_info rev;
389         /* I think we want full paths, even if we're in a subdirectory. */
390         init_revisions(&rev, NULL);
391         rev.diffopt.flags = opts->flags;
392         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
393         diff_setup_done(&rev.diffopt);
394         add_pending_object(&rev, head, NULL);
395         run_diff_index(&rev, 0);
396 }
397
398 static void describe_detached_head(const char *msg, struct commit *commit)
399 {
400         struct strbuf sb = STRBUF_INIT;
401         if (!parse_commit(commit))
402                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
403         fprintf(stderr, "%s %s... %s\n", msg,
404                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
405         strbuf_release(&sb);
406 }
407
408 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
409                       int worktree, int *writeout_error)
410 {
411         struct unpack_trees_options opts;
412         struct tree_desc tree_desc;
413
414         memset(&opts, 0, sizeof(opts));
415         opts.head_idx = -1;
416         opts.update = worktree;
417         opts.skip_unmerged = !worktree;
418         opts.reset = 1;
419         opts.merge = 1;
420         opts.fn = oneway_merge;
421         opts.verbose_update = o->show_progress;
422         opts.src_index = &the_index;
423         opts.dst_index = &the_index;
424         parse_tree(tree);
425         init_tree_desc(&tree_desc, tree->buffer, tree->size);
426         switch (unpack_trees(1, &tree_desc, &opts)) {
427         case -2:
428                 *writeout_error = 1;
429                 /*
430                  * We return 0 nevertheless, as the index is all right
431                  * and more importantly we have made best efforts to
432                  * update paths in the work tree, and we cannot revert
433                  * them.
434                  */
435         case 0:
436                 return 0;
437         default:
438                 return 128;
439         }
440 }
441
442 struct branch_info {
443         const char *name; /* The short name used */
444         const char *path; /* The full name of a real branch */
445         struct commit *commit; /* The named commit */
446         /*
447          * if not null the branch is detached because it's already
448          * checked out in this checkout
449          */
450         char *checkout;
451 };
452
453 static void setup_branch_path(struct branch_info *branch)
454 {
455         struct strbuf buf = STRBUF_INIT;
456
457         strbuf_branchname(&buf, branch->name);
458         if (strcmp(buf.buf, branch->name))
459                 branch->name = xstrdup(buf.buf);
460         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
461         branch->path = strbuf_detach(&buf, NULL);
462 }
463
464 static int merge_working_tree(const struct checkout_opts *opts,
465                               struct branch_info *old,
466                               struct branch_info *new,
467                               int *writeout_error)
468 {
469         int ret;
470         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
471
472         hold_locked_index(lock_file, 1);
473         if (read_cache_preload(NULL) < 0)
474                 return error(_("corrupt index file"));
475
476         resolve_undo_clear();
477         if (opts->force) {
478                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
479                 if (ret)
480                         return ret;
481         } else {
482                 struct tree_desc trees[2];
483                 struct tree *tree;
484                 struct unpack_trees_options topts;
485
486                 memset(&topts, 0, sizeof(topts));
487                 topts.head_idx = -1;
488                 topts.src_index = &the_index;
489                 topts.dst_index = &the_index;
490
491                 setup_unpack_trees_porcelain(&topts, "checkout");
492
493                 refresh_cache(REFRESH_QUIET);
494
495                 if (unmerged_cache()) {
496                         error(_("you need to resolve your current index first"));
497                         return 1;
498                 }
499
500                 /* 2-way merge to the new branch */
501                 topts.initial_checkout = is_cache_unborn();
502                 topts.update = 1;
503                 topts.merge = 1;
504                 topts.gently = opts->merge && old->commit;
505                 topts.verbose_update = opts->show_progress;
506                 topts.fn = twoway_merge;
507                 if (opts->overwrite_ignore) {
508                         topts.dir = xcalloc(1, sizeof(*topts.dir));
509                         topts.dir->flags |= DIR_SHOW_IGNORED;
510                         setup_standard_excludes(topts.dir);
511                 }
512                 tree = parse_tree_indirect(old->commit ?
513                                            old->commit->object.oid.hash :
514                                            EMPTY_TREE_SHA1_BIN);
515                 init_tree_desc(&trees[0], tree->buffer, tree->size);
516                 tree = parse_tree_indirect(new->commit->object.oid.hash);
517                 init_tree_desc(&trees[1], tree->buffer, tree->size);
518
519                 ret = unpack_trees(2, trees, &topts);
520                 if (ret == -1) {
521                         /*
522                          * Unpack couldn't do a trivial merge; either
523                          * give up or do a real merge, depending on
524                          * whether the merge flag was used.
525                          */
526                         struct tree *result;
527                         struct tree *work;
528                         struct merge_options o;
529                         if (!opts->merge)
530                                 return 1;
531
532                         /*
533                          * Without old->commit, the below is the same as
534                          * the two-tree unpack we already tried and failed.
535                          */
536                         if (!old->commit)
537                                 return 1;
538
539                         /* Do more real merge */
540
541                         /*
542                          * We update the index fully, then write the
543                          * tree from the index, then merge the new
544                          * branch with the current tree, with the old
545                          * branch as the base. Then we reset the index
546                          * (but not the working tree) to the new
547                          * branch, leaving the working tree as the
548                          * merged version, but skipping unmerged
549                          * entries in the index.
550                          */
551
552                         add_files_to_cache(NULL, NULL, 0);
553                         /*
554                          * NEEDSWORK: carrying over local changes
555                          * when branches have different end-of-line
556                          * normalization (or clean+smudge rules) is
557                          * a pain; plumb in an option to set
558                          * o.renormalize?
559                          */
560                         init_merge_options(&o);
561                         o.verbosity = 0;
562                         work = write_tree_from_memory(&o);
563
564                         ret = reset_tree(new->commit->tree, opts, 1,
565                                          writeout_error);
566                         if (ret)
567                                 return ret;
568                         o.ancestor = old->name;
569                         o.branch1 = new->name;
570                         o.branch2 = "local";
571                         merge_trees(&o, new->commit->tree, work,
572                                 old->commit->tree, &result);
573                         ret = reset_tree(new->commit->tree, opts, 0,
574                                          writeout_error);
575                         if (ret)
576                                 return ret;
577                 }
578         }
579
580         if (!active_cache_tree)
581                 active_cache_tree = cache_tree();
582
583         if (!cache_tree_fully_valid(active_cache_tree))
584                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
585
586         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
587                 die(_("unable to write new index file"));
588
589         if (!opts->force && !opts->quiet)
590                 show_local_changes(&new->commit->object, &opts->diff_options);
591
592         return 0;
593 }
594
595 static void report_tracking(struct branch_info *new)
596 {
597         struct strbuf sb = STRBUF_INIT;
598         struct branch *branch = branch_get(new->name);
599
600         if (!format_tracking_info(branch, &sb))
601                 return;
602         fputs(sb.buf, stdout);
603         strbuf_release(&sb);
604 }
605
606 static void update_refs_for_switch(const struct checkout_opts *opts,
607                                    struct branch_info *old,
608                                    struct branch_info *new)
609 {
610         struct strbuf msg = STRBUF_INIT;
611         const char *old_desc, *reflog_msg;
612         if (opts->new_branch) {
613                 if (opts->new_orphan_branch) {
614                         if (opts->new_branch_log && !log_all_ref_updates) {
615                                 int ret;
616                                 char *refname;
617                                 struct strbuf err = STRBUF_INIT;
618
619                                 refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
620                                 ret = safe_create_reflog(refname, 1, &err);
621                                 free(refname);
622                                 if (ret) {
623                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
624                                                 opts->new_orphan_branch, err.buf);
625                                         strbuf_release(&err);
626                                         return;
627                                 }
628                                 strbuf_release(&err);
629                         }
630                 }
631                 else
632                         create_branch(old->name, opts->new_branch, new->name,
633                                       opts->new_branch_force ? 1 : 0,
634                                       opts->new_branch_log,
635                                       opts->new_branch_force ? 1 : 0,
636                                       opts->quiet,
637                                       opts->track);
638                 new->name = opts->new_branch;
639                 setup_branch_path(new);
640         }
641
642         old_desc = old->name;
643         if (!old_desc && old->commit)
644                 old_desc = oid_to_hex(&old->commit->object.oid);
645
646         reflog_msg = getenv("GIT_REFLOG_ACTION");
647         if (!reflog_msg)
648                 strbuf_addf(&msg, "checkout: moving from %s to %s",
649                         old_desc ? old_desc : "(invalid)", new->name);
650         else
651                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
652
653         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
654                 /* Nothing to do. */
655         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
656                 update_ref(msg.buf, "HEAD", new->commit->object.oid.hash, NULL,
657                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
658                 if (!opts->quiet) {
659                         if (old->path && advice_detached_head)
660                                 detach_advice(new->name);
661                         describe_detached_head(_("HEAD is now at"), new->commit);
662                 }
663         } else if (new->path) { /* Switch branches. */
664                 if (create_symref("HEAD", new->path, msg.buf) < 0)
665                         die(_("unable to update HEAD"));
666                 if (!opts->quiet) {
667                         if (old->path && !strcmp(new->path, old->path)) {
668                                 if (opts->new_branch_force)
669                                         fprintf(stderr, _("Reset branch '%s'\n"),
670                                                 new->name);
671                                 else
672                                         fprintf(stderr, _("Already on '%s'\n"),
673                                                 new->name);
674                         } else if (opts->new_branch) {
675                                 if (opts->branch_exists)
676                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
677                                 else
678                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
679                         } else {
680                                 fprintf(stderr, _("Switched to branch '%s'\n"),
681                                         new->name);
682                         }
683                 }
684                 if (old->path && old->name) {
685                         if (!ref_exists(old->path) && reflog_exists(old->path))
686                                 delete_reflog(old->path);
687                 }
688         }
689         remove_branch_state();
690         strbuf_release(&msg);
691         if (!opts->quiet &&
692             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
693                 report_tracking(new);
694 }
695
696 static int add_pending_uninteresting_ref(const char *refname,
697                                          const struct object_id *oid,
698                                          int flags, void *cb_data)
699 {
700         add_pending_sha1(cb_data, refname, oid->hash, UNINTERESTING);
701         return 0;
702 }
703
704 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
705 {
706         strbuf_addstr(sb, "  ");
707         strbuf_addstr(sb,
708                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
709         strbuf_addch(sb, ' ');
710         if (!parse_commit(commit))
711                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
712         strbuf_addch(sb, '\n');
713 }
714
715 #define ORPHAN_CUTOFF 4
716 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
717 {
718         struct commit *c, *last = NULL;
719         struct strbuf sb = STRBUF_INIT;
720         int lost = 0;
721         while ((c = get_revision(revs)) != NULL) {
722                 if (lost < ORPHAN_CUTOFF)
723                         describe_one_orphan(&sb, c);
724                 last = c;
725                 lost++;
726         }
727         if (ORPHAN_CUTOFF < lost) {
728                 int more = lost - ORPHAN_CUTOFF;
729                 if (more == 1)
730                         describe_one_orphan(&sb, last);
731                 else
732                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
733         }
734
735         fprintf(stderr,
736                 Q_(
737                 /* The singular version */
738                 "Warning: you are leaving %d commit behind, "
739                 "not connected to\n"
740                 "any of your branches:\n\n"
741                 "%s\n",
742                 /* The plural version */
743                 "Warning: you are leaving %d commits behind, "
744                 "not connected to\n"
745                 "any of your branches:\n\n"
746                 "%s\n",
747                 /* Give ngettext() the count */
748                 lost),
749                 lost,
750                 sb.buf);
751         strbuf_release(&sb);
752
753         if (advice_detached_head)
754                 fprintf(stderr,
755                         Q_(
756                         /* The singular version */
757                         "If you want to keep it by creating a new branch, "
758                         "this may be a good time\nto do so with:\n\n"
759                         " git branch <new-branch-name> %s\n\n",
760                         /* The plural version */
761                         "If you want to keep them by creating a new branch, "
762                         "this may be a good time\nto do so with:\n\n"
763                         " git branch <new-branch-name> %s\n\n",
764                         /* Give ngettext() the count */
765                         lost),
766                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
767 }
768
769 /*
770  * We are about to leave commit that was at the tip of a detached
771  * HEAD.  If it is not reachable from any ref, this is the last chance
772  * for the user to do so without resorting to reflog.
773  */
774 static void orphaned_commit_warning(struct commit *old, struct commit *new)
775 {
776         struct rev_info revs;
777         struct object *object = &old->object;
778         struct object_array refs;
779
780         init_revisions(&revs, NULL);
781         setup_revisions(0, NULL, &revs, NULL);
782
783         object->flags &= ~UNINTERESTING;
784         add_pending_object(&revs, object, oid_to_hex(&object->oid));
785
786         for_each_ref(add_pending_uninteresting_ref, &revs);
787         add_pending_sha1(&revs, "HEAD", new->object.oid.hash, UNINTERESTING);
788
789         refs = revs.pending;
790         revs.leak_pending = 1;
791
792         if (prepare_revision_walk(&revs))
793                 die(_("internal error in revision walk"));
794         if (!(old->object.flags & UNINTERESTING))
795                 suggest_reattach(old, &revs);
796         else
797                 describe_detached_head(_("Previous HEAD position was"), old);
798
799         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
800         free(refs.objects);
801 }
802
803 static int switch_branches(const struct checkout_opts *opts,
804                            struct branch_info *new)
805 {
806         int ret = 0;
807         struct branch_info old;
808         void *path_to_free;
809         unsigned char rev[20];
810         int flag, writeout_error = 0;
811         memset(&old, 0, sizeof(old));
812         old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
813         old.commit = lookup_commit_reference_gently(rev, 1);
814         if (!(flag & REF_ISSYMREF))
815                 old.path = NULL;
816
817         if (old.path)
818                 skip_prefix(old.path, "refs/heads/", &old.name);
819
820         if (!new->name) {
821                 new->name = "HEAD";
822                 new->commit = old.commit;
823                 if (!new->commit)
824                         die(_("You are on a branch yet to be born"));
825                 parse_commit_or_die(new->commit);
826         }
827
828         ret = merge_working_tree(opts, &old, new, &writeout_error);
829         if (ret) {
830                 free(path_to_free);
831                 return ret;
832         }
833
834         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
835                 orphaned_commit_warning(old.commit, new->commit);
836
837         update_refs_for_switch(opts, &old, new);
838
839         ret = post_checkout_hook(old.commit, new->commit, 1);
840         free(path_to_free);
841         return ret || writeout_error;
842 }
843
844 static int git_checkout_config(const char *var, const char *value, void *cb)
845 {
846         if (!strcmp(var, "diff.ignoresubmodules")) {
847                 struct checkout_opts *opts = cb;
848                 handle_ignore_submodules_arg(&opts->diff_options, value);
849                 return 0;
850         }
851
852         if (starts_with(var, "submodule."))
853                 return parse_submodule_config_option(var, value);
854
855         return git_xmerge_config(var, value, NULL);
856 }
857
858 struct tracking_name_data {
859         /* const */ char *src_ref;
860         char *dst_ref;
861         unsigned char *dst_sha1;
862         int unique;
863 };
864
865 static int check_tracking_name(struct remote *remote, void *cb_data)
866 {
867         struct tracking_name_data *cb = cb_data;
868         struct refspec query;
869         memset(&query, 0, sizeof(struct refspec));
870         query.src = cb->src_ref;
871         if (remote_find_tracking(remote, &query) ||
872             get_sha1(query.dst, cb->dst_sha1)) {
873                 free(query.dst);
874                 return 0;
875         }
876         if (cb->dst_ref) {
877                 free(query.dst);
878                 cb->unique = 0;
879                 return 0;
880         }
881         cb->dst_ref = query.dst;
882         return 0;
883 }
884
885 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
886 {
887         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
888         char src_ref[PATH_MAX];
889         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
890         cb_data.src_ref = src_ref;
891         cb_data.dst_sha1 = sha1;
892         for_each_remote(check_tracking_name, &cb_data);
893         if (cb_data.unique)
894                 return cb_data.dst_ref;
895         free(cb_data.dst_ref);
896         return NULL;
897 }
898
899 static int parse_branchname_arg(int argc, const char **argv,
900                                 int dwim_new_local_branch_ok,
901                                 struct branch_info *new,
902                                 struct checkout_opts *opts,
903                                 unsigned char rev[20])
904 {
905         struct tree **source_tree = &opts->source_tree;
906         const char **new_branch = &opts->new_branch;
907         int argcount = 0;
908         unsigned char branch_rev[20];
909         const char *arg;
910         int dash_dash_pos;
911         int has_dash_dash = 0;
912         int i;
913
914         /*
915          * case 1: git checkout <ref> -- [<paths>]
916          *
917          *   <ref> must be a valid tree, everything after the '--' must be
918          *   a path.
919          *
920          * case 2: git checkout -- [<paths>]
921          *
922          *   everything after the '--' must be paths.
923          *
924          * case 3: git checkout <something> [--]
925          *
926          *   (a) If <something> is a commit, that is to
927          *       switch to the branch or detach HEAD at it.  As a special case,
928          *       if <something> is A...B (missing A or B means HEAD but you can
929          *       omit at most one side), and if there is a unique merge base
930          *       between A and B, A...B names that merge base.
931          *
932          *   (b) If <something> is _not_ a commit, either "--" is present
933          *       or <something> is not a path, no -t or -b was given, and
934          *       and there is a tracking branch whose name is <something>
935          *       in one and only one remote, then this is a short-hand to
936          *       fork local <something> from that remote-tracking branch.
937          *
938          *   (c) Otherwise, if "--" is present, treat it like case (1).
939          *
940          *   (d) Otherwise :
941          *       - if it's a reference, treat it like case (1)
942          *       - else if it's a path, treat it like case (2)
943          *       - else: fail.
944          *
945          * case 4: git checkout <something> <paths>
946          *
947          *   The first argument must not be ambiguous.
948          *   - If it's *only* a reference, treat it like case (1).
949          *   - If it's only a path, treat it like case (2).
950          *   - else: fail.
951          *
952          */
953         if (!argc)
954                 return 0;
955
956         arg = argv[0];
957         dash_dash_pos = -1;
958         for (i = 0; i < argc; i++) {
959                 if (!strcmp(argv[i], "--")) {
960                         dash_dash_pos = i;
961                         break;
962                 }
963         }
964         if (dash_dash_pos == 0)
965                 return 1; /* case (2) */
966         else if (dash_dash_pos == 1)
967                 has_dash_dash = 1; /* case (3) or (1) */
968         else if (dash_dash_pos >= 2)
969                 die(_("only one reference expected, %d given."), dash_dash_pos);
970
971         if (!strcmp(arg, "-"))
972                 arg = "@{-1}";
973
974         if (get_sha1_mb(arg, rev)) {
975                 /*
976                  * Either case (3) or (4), with <something> not being
977                  * a commit, or an attempt to use case (1) with an
978                  * invalid ref.
979                  *
980                  * It's likely an error, but we need to find out if
981                  * we should auto-create the branch, case (3).(b).
982                  */
983                 int recover_with_dwim = dwim_new_local_branch_ok;
984
985                 if (!has_dash_dash &&
986                     (check_filename(NULL, arg) || !no_wildcard(arg)))
987                         recover_with_dwim = 0;
988                 /*
989                  * Accept "git checkout foo" and "git checkout foo --"
990                  * as candidates for dwim.
991                  */
992                 if (!(argc == 1 && !has_dash_dash) &&
993                     !(argc == 2 && has_dash_dash))
994                         recover_with_dwim = 0;
995
996                 if (recover_with_dwim) {
997                         const char *remote = unique_tracking_name(arg, rev);
998                         if (remote) {
999                                 *new_branch = arg;
1000                                 arg = remote;
1001                                 /* DWIMmed to create local branch, case (3).(b) */
1002                         } else {
1003                                 recover_with_dwim = 0;
1004                         }
1005                 }
1006
1007                 if (!recover_with_dwim) {
1008                         if (has_dash_dash)
1009                                 die(_("invalid reference: %s"), arg);
1010                         return argcount;
1011                 }
1012         }
1013
1014         /* we can't end up being in (2) anymore, eat the argument */
1015         argcount++;
1016         argv++;
1017         argc--;
1018
1019         new->name = arg;
1020         setup_branch_path(new);
1021
1022         if (!check_refname_format(new->path, 0) &&
1023             !read_ref(new->path, branch_rev))
1024                 hashcpy(rev, branch_rev);
1025         else
1026                 new->path = NULL; /* not an existing branch */
1027
1028         new->commit = lookup_commit_reference_gently(rev, 1);
1029         if (!new->commit) {
1030                 /* not a commit */
1031                 *source_tree = parse_tree_indirect(rev);
1032         } else {
1033                 parse_commit_or_die(new->commit);
1034                 *source_tree = new->commit->tree;
1035         }
1036
1037         if (!*source_tree)                   /* case (1): want a tree */
1038                 die(_("reference is not a tree: %s"), arg);
1039         if (!has_dash_dash) {/* case (3).(d) -> (1) */
1040                 /*
1041                  * Do not complain the most common case
1042                  *      git checkout branch
1043                  * even if there happen to be a file called 'branch';
1044                  * it would be extremely annoying.
1045                  */
1046                 if (argc)
1047                         verify_non_filename(NULL, arg);
1048         } else {
1049                 argcount++;
1050                 argv++;
1051                 argc--;
1052         }
1053
1054         return argcount;
1055 }
1056
1057 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1058 {
1059         int status;
1060         struct strbuf branch_ref = STRBUF_INIT;
1061
1062         if (!opts->new_branch)
1063                 die(_("You are on a branch yet to be born"));
1064         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1065         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1066         strbuf_release(&branch_ref);
1067         if (!opts->quiet)
1068                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1069                         opts->new_branch);
1070         return status;
1071 }
1072
1073 static int checkout_branch(struct checkout_opts *opts,
1074                            struct branch_info *new)
1075 {
1076         if (opts->pathspec.nr)
1077                 die(_("paths cannot be used with switching branches"));
1078
1079         if (opts->patch_mode)
1080                 die(_("'%s' cannot be used with switching branches"),
1081                     "--patch");
1082
1083         if (opts->writeout_stage)
1084                 die(_("'%s' cannot be used with switching branches"),
1085                     "--ours/--theirs");
1086
1087         if (opts->force && opts->merge)
1088                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1089
1090         if (opts->force_detach && opts->new_branch)
1091                 die(_("'%s' cannot be used with '%s'"),
1092                     "--detach", "-b/-B/--orphan");
1093
1094         if (opts->new_orphan_branch) {
1095                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1096                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1097         } else if (opts->force_detach) {
1098                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1099                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1100         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1101                 opts->track = git_branch_track;
1102
1103         if (new->name && !new->commit)
1104                 die(_("Cannot switch branch to a non-commit '%s'"),
1105                     new->name);
1106
1107         if (new->path && !opts->force_detach && !opts->new_branch &&
1108             !opts->ignore_other_worktrees) {
1109                 unsigned char sha1[20];
1110                 int flag;
1111                 char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
1112                 if (head_ref &&
1113                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1114                         die_if_checked_out(new->path);
1115                 free(head_ref);
1116         }
1117
1118         if (!new->commit && opts->new_branch) {
1119                 unsigned char rev[20];
1120                 int flag;
1121
1122                 if (!read_ref_full("HEAD", 0, rev, &flag) &&
1123                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1124                         return switch_unborn_to_new_branch(opts);
1125         }
1126         return switch_branches(opts, new);
1127 }
1128
1129 int cmd_checkout(int argc, const char **argv, const char *prefix)
1130 {
1131         struct checkout_opts opts;
1132         struct branch_info new;
1133         char *conflict_style = NULL;
1134         int dwim_new_local_branch = 1;
1135         struct option options[] = {
1136                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1137                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1138                            N_("create and checkout a new branch")),
1139                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1140                            N_("create/reset and checkout a branch")),
1141                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1142                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1143                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1144                         BRANCH_TRACK_EXPLICIT),
1145                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1146                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1147                             2),
1148                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1149                             3),
1150                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1151                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1152                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1153                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1154                            N_("conflict style (merge or diff3)")),
1155                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1156                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1157                          N_("do not limit pathspecs to sparse entries only")),
1158                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1159                                 N_("second guess 'git checkout <no-such-branch>'")),
1160                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1161                          N_("do not check if another worktree is holding the given ref")),
1162                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1163                 OPT_END(),
1164         };
1165
1166         memset(&opts, 0, sizeof(opts));
1167         memset(&new, 0, sizeof(new));
1168         opts.overwrite_ignore = 1;
1169         opts.prefix = prefix;
1170         opts.show_progress = -1;
1171
1172         gitmodules_config();
1173         git_config(git_checkout_config, &opts);
1174
1175         opts.track = BRANCH_TRACK_UNSPECIFIED;
1176
1177         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1178                              PARSE_OPT_KEEP_DASHDASH);
1179
1180         if (opts.show_progress < 0) {
1181                 if (opts.quiet)
1182                         opts.show_progress = 0;
1183                 else
1184                         opts.show_progress = isatty(2);
1185         }
1186
1187         if (conflict_style) {
1188                 opts.merge = 1; /* implied */
1189                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1190         }
1191
1192         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1193                 die(_("-b, -B and --orphan are mutually exclusive"));
1194
1195         /*
1196          * From here on, new_branch will contain the branch to be checked out,
1197          * and new_branch_force and new_orphan_branch will tell us which one of
1198          * -b/-B/--orphan is being used.
1199          */
1200         if (opts.new_branch_force)
1201                 opts.new_branch = opts.new_branch_force;
1202
1203         if (opts.new_orphan_branch)
1204                 opts.new_branch = opts.new_orphan_branch;
1205
1206         /* --track without -b/-B/--orphan should DWIM */
1207         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1208                 const char *argv0 = argv[0];
1209                 if (!argc || !strcmp(argv0, "--"))
1210                         die (_("--track needs a branch name"));
1211                 skip_prefix(argv0, "refs/", &argv0);
1212                 skip_prefix(argv0, "remotes/", &argv0);
1213                 argv0 = strchr(argv0, '/');
1214                 if (!argv0 || !argv0[1])
1215                         die (_("Missing branch name; try -b"));
1216                 opts.new_branch = argv0 + 1;
1217         }
1218
1219         /*
1220          * Extract branch name from command line arguments, so
1221          * all that is left is pathspecs.
1222          *
1223          * Handle
1224          *
1225          *  1) git checkout <tree> -- [<paths>]
1226          *  2) git checkout -- [<paths>]
1227          *  3) git checkout <something> [<paths>]
1228          *
1229          * including "last branch" syntax and DWIM-ery for names of
1230          * remote branches, erroring out for invalid or ambiguous cases.
1231          */
1232         if (argc) {
1233                 unsigned char rev[20];
1234                 int dwim_ok =
1235                         !opts.patch_mode &&
1236                         dwim_new_local_branch &&
1237                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1238                         !opts.new_branch;
1239                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1240                                              &new, &opts, rev);
1241                 argv += n;
1242                 argc -= n;
1243         }
1244
1245         if (argc) {
1246                 parse_pathspec(&opts.pathspec, 0,
1247                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1248                                prefix, argv);
1249
1250                 if (!opts.pathspec.nr)
1251                         die(_("invalid path specification"));
1252
1253                 /*
1254                  * Try to give more helpful suggestion.
1255                  * new_branch && argc > 1 will be caught later.
1256                  */
1257                 if (opts.new_branch && argc == 1)
1258                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1259                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1260                             opts.new_branch, argv[0]);
1261
1262                 if (opts.force_detach)
1263                         die(_("git checkout: --detach does not take a path argument '%s'"),
1264                             argv[0]);
1265
1266                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1267                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1268                               "checking out of the index."));
1269         }
1270
1271         if (opts.new_branch) {
1272                 struct strbuf buf = STRBUF_INIT;
1273
1274                 opts.branch_exists =
1275                         validate_new_branchname(opts.new_branch, &buf,
1276                                                 !!opts.new_branch_force,
1277                                                 !!opts.new_branch_force);
1278
1279                 strbuf_release(&buf);
1280         }
1281
1282         if (opts.patch_mode || opts.pathspec.nr)
1283                 return checkout_paths(&opts, new.name);
1284         else
1285                 return checkout_branch(&opts, &new);
1286 }