Merge branch 'kk/maint-for-each-ref-multi-sort' into maint-1.7.11
[git] / builtin / checkout.c
1 #include "cache.h"
2 #include "builtin.h"
3 #include "parse-options.h"
4 #include "refs.h"
5 #include "commit.h"
6 #include "tree.h"
7 #include "tree-walk.h"
8 #include "cache-tree.h"
9 #include "unpack-trees.h"
10 #include "dir.h"
11 #include "run-command.h"
12 #include "merge-recursive.h"
13 #include "branch.h"
14 #include "diff.h"
15 #include "revision.h"
16 #include "remote.h"
17 #include "blob.h"
18 #include "xdiff-interface.h"
19 #include "ll-merge.h"
20 #include "resolve-undo.h"
21 #include "submodule.h"
22 #include "argv-array.h"
23
24 static const char * const checkout_usage[] = {
25         "git checkout [options] <branch>",
26         "git checkout [options] [<branch>] -- <file>...",
27         NULL,
28 };
29
30 struct checkout_opts {
31         int quiet;
32         int merge;
33         int force;
34         int force_detach;
35         int writeout_stage;
36         int writeout_error;
37         int overwrite_ignore;
38
39         /* not set by parse_options */
40         int branch_exists;
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
50 static int post_checkout_hook(struct commit *old, struct commit *new,
51                               int changed)
52 {
53         return run_hook(NULL, "post-checkout",
54                         sha1_to_hex(old ? old->object.sha1 : null_sha1),
55                         sha1_to_hex(new ? new->object.sha1 : null_sha1),
56                         changed ? "1" : "0", NULL);
57         /* "new" can be NULL when checking out from the index before
58            a commit exists. */
59
60 }
61
62 static int update_some(const unsigned char *sha1, const char *base, int baselen,
63                 const char *pathname, unsigned mode, int stage, void *context)
64 {
65         int len;
66         struct cache_entry *ce;
67
68         if (S_ISDIR(mode))
69                 return READ_TREE_RECURSIVE;
70
71         len = baselen + strlen(pathname);
72         ce = xcalloc(1, cache_entry_size(len));
73         hashcpy(ce->sha1, sha1);
74         memcpy(ce->name, base, baselen);
75         memcpy(ce->name + baselen, pathname, len - baselen);
76         ce->ce_flags = create_ce_flags(len, 0) | CE_UPDATE;
77         ce->ce_mode = create_ce_mode(mode);
78         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
79         return 0;
80 }
81
82 static int read_tree_some(struct tree *tree, const char **pathspec)
83 {
84         struct pathspec ps;
85         init_pathspec(&ps, pathspec);
86         read_tree_recursive(tree, "", 0, 0, &ps, update_some, NULL);
87         free_pathspec(&ps);
88
89         /* update the index with the given tree's info
90          * for all args, expanding wildcards, and exit
91          * with any non-zero return code.
92          */
93         return 0;
94 }
95
96 static int skip_same_name(struct cache_entry *ce, int pos)
97 {
98         while (++pos < active_nr &&
99                !strcmp(active_cache[pos]->name, ce->name))
100                 ; /* skip */
101         return pos;
102 }
103
104 static int check_stage(int stage, struct cache_entry *ce, int pos)
105 {
106         while (pos < active_nr &&
107                !strcmp(active_cache[pos]->name, ce->name)) {
108                 if (ce_stage(active_cache[pos]) == stage)
109                         return 0;
110                 pos++;
111         }
112         if (stage == 2)
113                 return error(_("path '%s' does not have our version"), ce->name);
114         else
115                 return error(_("path '%s' does not have their version"), ce->name);
116 }
117
118 static int check_stages(unsigned stages, struct cache_entry *ce, int pos)
119 {
120         unsigned seen = 0;
121         const char *name = ce->name;
122
123         while (pos < active_nr) {
124                 ce = active_cache[pos];
125                 if (strcmp(name, ce->name))
126                         break;
127                 seen |= (1 << ce_stage(ce));
128                 pos++;
129         }
130         if ((stages & seen) != stages)
131                 return error(_("path '%s' does not have all necessary versions"),
132                              name);
133         return 0;
134 }
135
136 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
137                           struct checkout *state)
138 {
139         while (pos < active_nr &&
140                !strcmp(active_cache[pos]->name, ce->name)) {
141                 if (ce_stage(active_cache[pos]) == stage)
142                         return checkout_entry(active_cache[pos], state, NULL);
143                 pos++;
144         }
145         if (stage == 2)
146                 return error(_("path '%s' does not have our version"), ce->name);
147         else
148                 return error(_("path '%s' does not have their version"), ce->name);
149 }
150
151 static int checkout_merged(int pos, struct checkout *state)
152 {
153         struct cache_entry *ce = active_cache[pos];
154         const char *path = ce->name;
155         mmfile_t ancestor, ours, theirs;
156         int status;
157         unsigned char sha1[20];
158         mmbuffer_t result_buf;
159         unsigned char threeway[3][20];
160         unsigned mode = 0;
161
162         memset(threeway, 0, sizeof(threeway));
163         while (pos < active_nr) {
164                 int stage;
165                 stage = ce_stage(ce);
166                 if (!stage || strcmp(path, ce->name))
167                         break;
168                 hashcpy(threeway[stage - 1], ce->sha1);
169                 if (stage == 2)
170                         mode = create_ce_mode(ce->ce_mode);
171                 pos++;
172                 ce = active_cache[pos];
173         }
174         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
175                 return error(_("path '%s' does not have necessary versions"), path);
176
177         read_mmblob(&ancestor, threeway[0]);
178         read_mmblob(&ours, threeway[1]);
179         read_mmblob(&theirs, threeway[2]);
180
181         /*
182          * NEEDSWORK: re-create conflicts from merges with
183          * merge.renormalize set, too
184          */
185         status = ll_merge(&result_buf, path, &ancestor, "base",
186                           &ours, "ours", &theirs, "theirs", NULL);
187         free(ancestor.ptr);
188         free(ours.ptr);
189         free(theirs.ptr);
190         if (status < 0 || !result_buf.ptr) {
191                 free(result_buf.ptr);
192                 return error(_("path '%s': cannot merge"), path);
193         }
194
195         /*
196          * NEEDSWORK:
197          * There is absolutely no reason to write this as a blob object
198          * and create a phony cache entry just to leak.  This hack is
199          * primarily to get to the write_entry() machinery that massages
200          * the contents to work-tree format and writes out which only
201          * allows it for a cache entry.  The code in write_entry() needs
202          * to be refactored to allow us to feed a <buffer, size, mode>
203          * instead of a cache entry.  Such a refactoring would help
204          * merge_recursive as well (it also writes the merge result to the
205          * object database even when it may contain conflicts).
206          */
207         if (write_sha1_file(result_buf.ptr, result_buf.size,
208                             blob_type, sha1))
209                 die(_("Unable to add merge result for '%s'"), path);
210         ce = make_cache_entry(mode, sha1, path, 2, 0);
211         if (!ce)
212                 die(_("make_cache_entry failed for path '%s'"), path);
213         status = checkout_entry(ce, state, NULL);
214         return status;
215 }
216
217 static int checkout_paths(struct tree *source_tree, const char **pathspec,
218                           const char *prefix, struct checkout_opts *opts)
219 {
220         int pos;
221         struct checkout state;
222         static char *ps_matched;
223         unsigned char rev[20];
224         int flag;
225         struct commit *head;
226         int errs = 0;
227         int stage = opts->writeout_stage;
228         int merge = opts->merge;
229         int newfd;
230         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
231
232         newfd = hold_locked_index(lock_file, 1);
233         if (read_cache_preload(pathspec) < 0)
234                 return error(_("corrupt index file"));
235
236         if (source_tree)
237                 read_tree_some(source_tree, pathspec);
238
239         for (pos = 0; pathspec[pos]; pos++)
240                 ;
241         ps_matched = xcalloc(1, pos);
242
243         for (pos = 0; pos < active_nr; pos++) {
244                 struct cache_entry *ce = active_cache[pos];
245                 if (source_tree && !(ce->ce_flags & CE_UPDATE))
246                         continue;
247                 match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
248         }
249
250         if (report_path_error(ps_matched, pathspec, prefix))
251                 return 1;
252
253         /* "checkout -m path" to recreate conflicted state */
254         if (opts->merge)
255                 unmerge_cache(pathspec);
256
257         /* Any unmerged paths? */
258         for (pos = 0; pos < active_nr; pos++) {
259                 struct cache_entry *ce = active_cache[pos];
260                 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
261                         if (!ce_stage(ce))
262                                 continue;
263                         if (opts->force) {
264                                 warning(_("path '%s' is unmerged"), ce->name);
265                         } else if (stage) {
266                                 errs |= check_stage(stage, ce, pos);
267                         } else if (opts->merge) {
268                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
269                         } else {
270                                 errs = 1;
271                                 error(_("path '%s' is unmerged"), ce->name);
272                         }
273                         pos = skip_same_name(ce, pos) - 1;
274                 }
275         }
276         if (errs)
277                 return 1;
278
279         /* Now we are committed to check them out */
280         memset(&state, 0, sizeof(state));
281         state.force = 1;
282         state.refresh_cache = 1;
283         for (pos = 0; pos < active_nr; pos++) {
284                 struct cache_entry *ce = active_cache[pos];
285                 if (source_tree && !(ce->ce_flags & CE_UPDATE))
286                         continue;
287                 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
288                         if (!ce_stage(ce)) {
289                                 errs |= checkout_entry(ce, &state, NULL);
290                                 continue;
291                         }
292                         if (stage)
293                                 errs |= checkout_stage(stage, ce, pos, &state);
294                         else if (merge)
295                                 errs |= checkout_merged(pos, &state);
296                         pos = skip_same_name(ce, pos) - 1;
297                 }
298         }
299
300         if (write_cache(newfd, active_cache, active_nr) ||
301             commit_locked_index(lock_file))
302                 die(_("unable to write new index file"));
303
304         read_ref_full("HEAD", rev, 0, &flag);
305         head = lookup_commit_reference_gently(rev, 1);
306
307         errs |= post_checkout_hook(head, head, 0);
308         return errs;
309 }
310
311 static void show_local_changes(struct object *head, struct diff_options *opts)
312 {
313         struct rev_info rev;
314         /* I think we want full paths, even if we're in a subdirectory. */
315         init_revisions(&rev, NULL);
316         rev.diffopt.flags = opts->flags;
317         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
318         diff_setup_done(&rev.diffopt);
319         add_pending_object(&rev, head, NULL);
320         run_diff_index(&rev, 0);
321 }
322
323 static void describe_detached_head(const char *msg, struct commit *commit)
324 {
325         struct strbuf sb = STRBUF_INIT;
326         parse_commit(commit);
327         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
328         fprintf(stderr, "%s %s... %s\n", msg,
329                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
330         strbuf_release(&sb);
331 }
332
333 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
334 {
335         struct unpack_trees_options opts;
336         struct tree_desc tree_desc;
337
338         memset(&opts, 0, sizeof(opts));
339         opts.head_idx = -1;
340         opts.update = worktree;
341         opts.skip_unmerged = !worktree;
342         opts.reset = 1;
343         opts.merge = 1;
344         opts.fn = oneway_merge;
345         opts.verbose_update = !o->quiet && isatty(2);
346         opts.src_index = &the_index;
347         opts.dst_index = &the_index;
348         parse_tree(tree);
349         init_tree_desc(&tree_desc, tree->buffer, tree->size);
350         switch (unpack_trees(1, &tree_desc, &opts)) {
351         case -2:
352                 o->writeout_error = 1;
353                 /*
354                  * We return 0 nevertheless, as the index is all right
355                  * and more importantly we have made best efforts to
356                  * update paths in the work tree, and we cannot revert
357                  * them.
358                  */
359         case 0:
360                 return 0;
361         default:
362                 return 128;
363         }
364 }
365
366 struct branch_info {
367         const char *name; /* The short name used */
368         const char *path; /* The full name of a real branch */
369         struct commit *commit; /* The named commit */
370 };
371
372 static void setup_branch_path(struct branch_info *branch)
373 {
374         struct strbuf buf = STRBUF_INIT;
375
376         strbuf_branchname(&buf, branch->name);
377         if (strcmp(buf.buf, branch->name))
378                 branch->name = xstrdup(buf.buf);
379         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
380         branch->path = strbuf_detach(&buf, NULL);
381 }
382
383 static int merge_working_tree(struct checkout_opts *opts,
384                               struct branch_info *old, struct branch_info *new)
385 {
386         int ret;
387         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
388         int newfd = hold_locked_index(lock_file, 1);
389
390         if (read_cache_preload(NULL) < 0)
391                 return error(_("corrupt index file"));
392
393         resolve_undo_clear();
394         if (opts->force) {
395                 ret = reset_tree(new->commit->tree, opts, 1);
396                 if (ret)
397                         return ret;
398         } else {
399                 struct tree_desc trees[2];
400                 struct tree *tree;
401                 struct unpack_trees_options topts;
402
403                 memset(&topts, 0, sizeof(topts));
404                 topts.head_idx = -1;
405                 topts.src_index = &the_index;
406                 topts.dst_index = &the_index;
407
408                 setup_unpack_trees_porcelain(&topts, "checkout");
409
410                 refresh_cache(REFRESH_QUIET);
411
412                 if (unmerged_cache()) {
413                         error(_("you need to resolve your current index first"));
414                         return 1;
415                 }
416
417                 /* 2-way merge to the new branch */
418                 topts.initial_checkout = is_cache_unborn();
419                 topts.update = 1;
420                 topts.merge = 1;
421                 topts.gently = opts->merge && old->commit;
422                 topts.verbose_update = !opts->quiet && isatty(2);
423                 topts.fn = twoway_merge;
424                 if (opts->overwrite_ignore) {
425                         topts.dir = xcalloc(1, sizeof(*topts.dir));
426                         topts.dir->flags |= DIR_SHOW_IGNORED;
427                         setup_standard_excludes(topts.dir);
428                 }
429                 tree = parse_tree_indirect(old->commit ?
430                                            old->commit->object.sha1 :
431                                            EMPTY_TREE_SHA1_BIN);
432                 init_tree_desc(&trees[0], tree->buffer, tree->size);
433                 tree = parse_tree_indirect(new->commit->object.sha1);
434                 init_tree_desc(&trees[1], tree->buffer, tree->size);
435
436                 ret = unpack_trees(2, trees, &topts);
437                 if (ret == -1) {
438                         /*
439                          * Unpack couldn't do a trivial merge; either
440                          * give up or do a real merge, depending on
441                          * whether the merge flag was used.
442                          */
443                         struct tree *result;
444                         struct tree *work;
445                         struct merge_options o;
446                         if (!opts->merge)
447                                 return 1;
448
449                         /*
450                          * Without old->commit, the below is the same as
451                          * the two-tree unpack we already tried and failed.
452                          */
453                         if (!old->commit)
454                                 return 1;
455
456                         /* Do more real merge */
457
458                         /*
459                          * We update the index fully, then write the
460                          * tree from the index, then merge the new
461                          * branch with the current tree, with the old
462                          * branch as the base. Then we reset the index
463                          * (but not the working tree) to the new
464                          * branch, leaving the working tree as the
465                          * merged version, but skipping unmerged
466                          * entries in the index.
467                          */
468
469                         add_files_to_cache(NULL, NULL, 0);
470                         /*
471                          * NEEDSWORK: carrying over local changes
472                          * when branches have different end-of-line
473                          * normalization (or clean+smudge rules) is
474                          * a pain; plumb in an option to set
475                          * o.renormalize?
476                          */
477                         init_merge_options(&o);
478                         o.verbosity = 0;
479                         work = write_tree_from_memory(&o);
480
481                         ret = reset_tree(new->commit->tree, opts, 1);
482                         if (ret)
483                                 return ret;
484                         o.ancestor = old->name;
485                         o.branch1 = new->name;
486                         o.branch2 = "local";
487                         merge_trees(&o, new->commit->tree, work,
488                                 old->commit->tree, &result);
489                         ret = reset_tree(new->commit->tree, opts, 0);
490                         if (ret)
491                                 return ret;
492                 }
493         }
494
495         if (write_cache(newfd, active_cache, active_nr) ||
496             commit_locked_index(lock_file))
497                 die(_("unable to write new index file"));
498
499         if (!opts->force && !opts->quiet)
500                 show_local_changes(&new->commit->object, &opts->diff_options);
501
502         return 0;
503 }
504
505 static void report_tracking(struct branch_info *new)
506 {
507         struct strbuf sb = STRBUF_INIT;
508         struct branch *branch = branch_get(new->name);
509
510         if (!format_tracking_info(branch, &sb))
511                 return;
512         fputs(sb.buf, stdout);
513         strbuf_release(&sb);
514 }
515
516 static void update_refs_for_switch(struct checkout_opts *opts,
517                                    struct branch_info *old,
518                                    struct branch_info *new)
519 {
520         struct strbuf msg = STRBUF_INIT;
521         const char *old_desc;
522         if (opts->new_branch) {
523                 if (opts->new_orphan_branch) {
524                         if (opts->new_branch_log && !log_all_ref_updates) {
525                                 int temp;
526                                 char log_file[PATH_MAX];
527                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
528
529                                 temp = log_all_ref_updates;
530                                 log_all_ref_updates = 1;
531                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
532                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
533                                             opts->new_orphan_branch);
534                                         log_all_ref_updates = temp;
535                                         return;
536                                 }
537                                 log_all_ref_updates = temp;
538                         }
539                 }
540                 else
541                         create_branch(old->name, opts->new_branch, new->name,
542                                       opts->new_branch_force ? 1 : 0,
543                                       opts->new_branch_log,
544                                       opts->new_branch_force ? 1 : 0,
545                                       opts->quiet,
546                                       opts->track);
547                 new->name = opts->new_branch;
548                 setup_branch_path(new);
549         }
550
551         old_desc = old->name;
552         if (!old_desc && old->commit)
553                 old_desc = sha1_to_hex(old->commit->object.sha1);
554         strbuf_addf(&msg, "checkout: moving from %s to %s",
555                     old_desc ? old_desc : "(invalid)", new->name);
556
557         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
558                 /* Nothing to do. */
559         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
560                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
561                            REF_NODEREF, DIE_ON_ERR);
562                 if (!opts->quiet) {
563                         if (old->path && advice_detached_head)
564                                 detach_advice(new->name);
565                         describe_detached_head(_("HEAD is now at"), new->commit);
566                 }
567         } else if (new->path) { /* Switch branches. */
568                 create_symref("HEAD", new->path, msg.buf);
569                 if (!opts->quiet) {
570                         if (old->path && !strcmp(new->path, old->path)) {
571                                 if (opts->new_branch_force)
572                                         fprintf(stderr, _("Reset branch '%s'\n"),
573                                                 new->name);
574                                 else
575                                         fprintf(stderr, _("Already on '%s'\n"),
576                                                 new->name);
577                         } else if (opts->new_branch) {
578                                 if (opts->branch_exists)
579                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
580                                 else
581                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
582                         } else {
583                                 fprintf(stderr, _("Switched to branch '%s'\n"),
584                                         new->name);
585                         }
586                 }
587                 if (old->path && old->name) {
588                         char log_file[PATH_MAX], ref_file[PATH_MAX];
589
590                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
591                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
592                         if (!file_exists(ref_file) && file_exists(log_file))
593                                 remove_path(log_file);
594                 }
595         }
596         remove_branch_state();
597         strbuf_release(&msg);
598         if (!opts->quiet &&
599             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
600                 report_tracking(new);
601 }
602
603 static int add_pending_uninteresting_ref(const char *refname,
604                                          const unsigned char *sha1,
605                                          int flags, void *cb_data)
606 {
607         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
608         return 0;
609 }
610
611 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
612 {
613         parse_commit(commit);
614         strbuf_addstr(sb, "  ");
615         strbuf_addstr(sb,
616                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
617         strbuf_addch(sb, ' ');
618         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
619         strbuf_addch(sb, '\n');
620 }
621
622 #define ORPHAN_CUTOFF 4
623 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
624 {
625         struct commit *c, *last = NULL;
626         struct strbuf sb = STRBUF_INIT;
627         int lost = 0;
628         while ((c = get_revision(revs)) != NULL) {
629                 if (lost < ORPHAN_CUTOFF)
630                         describe_one_orphan(&sb, c);
631                 last = c;
632                 lost++;
633         }
634         if (ORPHAN_CUTOFF < lost) {
635                 int more = lost - ORPHAN_CUTOFF;
636                 if (more == 1)
637                         describe_one_orphan(&sb, last);
638                 else
639                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
640         }
641
642         fprintf(stderr,
643                 Q_(
644                 /* The singular version */
645                 "Warning: you are leaving %d commit behind, "
646                 "not connected to\n"
647                 "any of your branches:\n\n"
648                 "%s\n",
649                 /* The plural version */
650                 "Warning: you are leaving %d commits behind, "
651                 "not connected to\n"
652                 "any of your branches:\n\n"
653                 "%s\n",
654                 /* Give ngettext() the count */
655                 lost),
656                 lost,
657                 sb.buf);
658         strbuf_release(&sb);
659
660         if (advice_detached_head)
661                 fprintf(stderr,
662                         _(
663                         "If you want to keep them by creating a new branch, "
664                         "this may be a good time\nto do so with:\n\n"
665                         " git branch new_branch_name %s\n\n"),
666                         sha1_to_hex(commit->object.sha1));
667 }
668
669 /*
670  * We are about to leave commit that was at the tip of a detached
671  * HEAD.  If it is not reachable from any ref, this is the last chance
672  * for the user to do so without resorting to reflog.
673  */
674 static void orphaned_commit_warning(struct commit *old, struct commit *new)
675 {
676         struct rev_info revs;
677         struct object *object = &old->object;
678         struct object_array refs;
679
680         init_revisions(&revs, NULL);
681         setup_revisions(0, NULL, &revs, NULL);
682
683         object->flags &= ~UNINTERESTING;
684         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
685
686         for_each_ref(add_pending_uninteresting_ref, &revs);
687         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
688
689         refs = revs.pending;
690         revs.leak_pending = 1;
691
692         if (prepare_revision_walk(&revs))
693                 die(_("internal error in revision walk"));
694         if (!(old->object.flags & UNINTERESTING))
695                 suggest_reattach(old, &revs);
696         else
697                 describe_detached_head(_("Previous HEAD position was"), old);
698
699         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
700         free(refs.objects);
701 }
702
703 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
704 {
705         int ret = 0;
706         struct branch_info old;
707         void *path_to_free;
708         unsigned char rev[20];
709         int flag;
710         memset(&old, 0, sizeof(old));
711         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
712         old.commit = lookup_commit_reference_gently(rev, 1);
713         if (!(flag & REF_ISSYMREF))
714                 old.path = NULL;
715
716         if (old.path && !prefixcmp(old.path, "refs/heads/"))
717                 old.name = old.path + strlen("refs/heads/");
718
719         if (!new->name) {
720                 new->name = "HEAD";
721                 new->commit = old.commit;
722                 if (!new->commit)
723                         die(_("You are on a branch yet to be born"));
724                 parse_commit(new->commit);
725         }
726
727         ret = merge_working_tree(opts, &old, new);
728         if (ret) {
729                 free(path_to_free);
730                 return ret;
731         }
732
733         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
734                 orphaned_commit_warning(old.commit, new->commit);
735
736         update_refs_for_switch(opts, &old, new);
737
738         ret = post_checkout_hook(old.commit, new->commit, 1);
739         free(path_to_free);
740         return ret || opts->writeout_error;
741 }
742
743 static int git_checkout_config(const char *var, const char *value, void *cb)
744 {
745         if (!strcmp(var, "diff.ignoresubmodules")) {
746                 struct checkout_opts *opts = cb;
747                 handle_ignore_submodules_arg(&opts->diff_options, value);
748                 return 0;
749         }
750
751         if (!prefixcmp(var, "submodule."))
752                 return parse_submodule_config_option(var, value);
753
754         return git_xmerge_config(var, value, NULL);
755 }
756
757 static int interactive_checkout(const char *revision, const char **pathspec,
758                                 struct checkout_opts *opts)
759 {
760         return run_add_interactive(revision, "--patch=checkout", pathspec);
761 }
762
763 struct tracking_name_data {
764         const char *name;
765         char *remote;
766         int unique;
767 };
768
769 static int check_tracking_name(const char *refname, const unsigned char *sha1,
770                                int flags, void *cb_data)
771 {
772         struct tracking_name_data *cb = cb_data;
773         const char *slash;
774
775         if (prefixcmp(refname, "refs/remotes/"))
776                 return 0;
777         slash = strchr(refname + 13, '/');
778         if (!slash || strcmp(slash + 1, cb->name))
779                 return 0;
780         if (cb->remote) {
781                 cb->unique = 0;
782                 return 0;
783         }
784         cb->remote = xstrdup(refname);
785         return 0;
786 }
787
788 static const char *unique_tracking_name(const char *name)
789 {
790         struct tracking_name_data cb_data = { NULL, NULL, 1 };
791         cb_data.name = name;
792         for_each_ref(check_tracking_name, &cb_data);
793         if (cb_data.unique)
794                 return cb_data.remote;
795         free(cb_data.remote);
796         return NULL;
797 }
798
799 static int parse_branchname_arg(int argc, const char **argv,
800                                 int dwim_new_local_branch_ok,
801                                 struct branch_info *new,
802                                 struct tree **source_tree,
803                                 unsigned char rev[20],
804                                 const char **new_branch)
805 {
806         int argcount = 0;
807         unsigned char branch_rev[20];
808         const char *arg;
809         int has_dash_dash;
810
811         /*
812          * case 1: git checkout <ref> -- [<paths>]
813          *
814          *   <ref> must be a valid tree, everything after the '--' must be
815          *   a path.
816          *
817          * case 2: git checkout -- [<paths>]
818          *
819          *   everything after the '--' must be paths.
820          *
821          * case 3: git checkout <something> [<paths>]
822          *
823          *   With no paths, if <something> is a commit, that is to
824          *   switch to the branch or detach HEAD at it.  As a special case,
825          *   if <something> is A...B (missing A or B means HEAD but you can
826          *   omit at most one side), and if there is a unique merge base
827          *   between A and B, A...B names that merge base.
828          *
829          *   With no paths, if <something> is _not_ a commit, no -t nor -b
830          *   was given, and there is a tracking branch whose name is
831          *   <something> in one and only one remote, then this is a short-hand
832          *   to fork local <something> from that remote-tracking branch.
833          *
834          *   Otherwise <something> shall not be ambiguous.
835          *   - If it's *only* a reference, treat it like case (1).
836          *   - If it's only a path, treat it like case (2).
837          *   - else: fail.
838          *
839          */
840         if (!argc)
841                 return 0;
842
843         if (!strcmp(argv[0], "--"))     /* case (2) */
844                 return 1;
845
846         arg = argv[0];
847         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
848
849         if (!strcmp(arg, "-"))
850                 arg = "@{-1}";
851
852         if (get_sha1_mb(arg, rev)) {
853                 if (has_dash_dash)          /* case (1) */
854                         die(_("invalid reference: %s"), arg);
855                 if (dwim_new_local_branch_ok &&
856                     !check_filename(NULL, arg) &&
857                     argc == 1) {
858                         const char *remote = unique_tracking_name(arg);
859                         if (!remote || get_sha1(remote, rev))
860                                 return argcount;
861                         *new_branch = arg;
862                         arg = remote;
863                         /* DWIMmed to create local branch */
864                 } else {
865                         return argcount;
866                 }
867         }
868
869         /* we can't end up being in (2) anymore, eat the argument */
870         argcount++;
871         argv++;
872         argc--;
873
874         new->name = arg;
875         setup_branch_path(new);
876
877         if (!check_refname_format(new->path, 0) &&
878             !read_ref(new->path, branch_rev))
879                 hashcpy(rev, branch_rev);
880         else
881                 new->path = NULL; /* not an existing branch */
882
883         new->commit = lookup_commit_reference_gently(rev, 1);
884         if (!new->commit) {
885                 /* not a commit */
886                 *source_tree = parse_tree_indirect(rev);
887         } else {
888                 parse_commit(new->commit);
889                 *source_tree = new->commit->tree;
890         }
891
892         if (!*source_tree)                   /* case (1): want a tree */
893                 die(_("reference is not a tree: %s"), arg);
894         if (!has_dash_dash) {/* case (3 -> 1) */
895                 /*
896                  * Do not complain the most common case
897                  *      git checkout branch
898                  * even if there happen to be a file called 'branch';
899                  * it would be extremely annoying.
900                  */
901                 if (argc)
902                         verify_non_filename(NULL, arg);
903         } else {
904                 argcount++;
905                 argv++;
906                 argc--;
907         }
908
909         return argcount;
910 }
911
912 static int switch_unborn_to_new_branch(struct checkout_opts *opts)
913 {
914         int status;
915         struct strbuf branch_ref = STRBUF_INIT;
916
917         if (!opts->new_branch)
918                 die(_("You are on a branch yet to be born"));
919         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
920         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
921         strbuf_release(&branch_ref);
922         return status;
923 }
924
925 int cmd_checkout(int argc, const char **argv, const char *prefix)
926 {
927         struct checkout_opts opts;
928         unsigned char rev[20];
929         struct branch_info new;
930         struct tree *source_tree = NULL;
931         char *conflict_style = NULL;
932         int patch_mode = 0;
933         int dwim_new_local_branch = 1;
934         struct option options[] = {
935                 OPT__QUIET(&opts.quiet, "suppress progress reporting"),
936                 OPT_STRING('b', NULL, &opts.new_branch, "branch",
937                            "create and checkout a new branch"),
938                 OPT_STRING('B', NULL, &opts.new_branch_force, "branch",
939                            "create/reset and checkout a branch"),
940                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "create reflog for new branch"),
941                 OPT_BOOLEAN(0, "detach", &opts.force_detach, "detach the HEAD at named commit"),
942                 OPT_SET_INT('t', "track",  &opts.track, "set upstream info for new branch",
943                         BRANCH_TRACK_EXPLICIT),
944                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, "new branch", "new unparented branch"),
945                 OPT_SET_INT('2', "ours", &opts.writeout_stage, "checkout our version for unmerged files",
946                             2),
947                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "checkout their version for unmerged files",
948                             3),
949                 OPT__FORCE(&opts.force, "force checkout (throw away local modifications)"),
950                 OPT_BOOLEAN('m', "merge", &opts.merge, "perform a 3-way merge with the new branch"),
951                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, "update ignored files (default)"),
952                 OPT_STRING(0, "conflict", &conflict_style, "style",
953                            "conflict style (merge or diff3)"),
954                 OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
955                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
956                   "second guess 'git checkout no-such-branch'",
957                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
958                 OPT_END(),
959         };
960
961         memset(&opts, 0, sizeof(opts));
962         memset(&new, 0, sizeof(new));
963         opts.overwrite_ignore = 1;
964
965         gitmodules_config();
966         git_config(git_checkout_config, &opts);
967
968         opts.track = BRANCH_TRACK_UNSPECIFIED;
969
970         argc = parse_options(argc, argv, prefix, options, checkout_usage,
971                              PARSE_OPT_KEEP_DASHDASH);
972
973         /* we can assume from now on new_branch = !new_branch_force */
974         if (opts.new_branch && opts.new_branch_force)
975                 die(_("-B cannot be used with -b"));
976
977         /* copy -B over to -b, so that we can just check the latter */
978         if (opts.new_branch_force)
979                 opts.new_branch = opts.new_branch_force;
980
981         if (patch_mode && (opts.track > 0 || opts.new_branch
982                            || opts.new_branch_log || opts.merge || opts.force
983                            || opts.force_detach))
984                 die (_("--patch is incompatible with all other options"));
985
986         if (opts.force_detach && (opts.new_branch || opts.new_orphan_branch))
987                 die(_("--detach cannot be used with -b/-B/--orphan"));
988         if (opts.force_detach && 0 < opts.track)
989                 die(_("--detach cannot be used with -t"));
990
991         /* --track without -b should DWIM */
992         if (0 < opts.track && !opts.new_branch) {
993                 const char *argv0 = argv[0];
994                 if (!argc || !strcmp(argv0, "--"))
995                         die (_("--track needs a branch name"));
996                 if (!prefixcmp(argv0, "refs/"))
997                         argv0 += 5;
998                 if (!prefixcmp(argv0, "remotes/"))
999                         argv0 += 8;
1000                 argv0 = strchr(argv0, '/');
1001                 if (!argv0 || !argv0[1])
1002                         die (_("Missing branch name; try -b"));
1003                 opts.new_branch = argv0 + 1;
1004         }
1005
1006         if (opts.new_orphan_branch) {
1007                 if (opts.new_branch)
1008                         die(_("--orphan and -b|-B are mutually exclusive"));
1009                 if (opts.track > 0)
1010                         die(_("--orphan cannot be used with -t"));
1011                 opts.new_branch = opts.new_orphan_branch;
1012         }
1013
1014         if (conflict_style) {
1015                 opts.merge = 1; /* implied */
1016                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1017         }
1018
1019         if (opts.force && opts.merge)
1020                 die(_("git checkout: -f and -m are incompatible"));
1021
1022         /*
1023          * Extract branch name from command line arguments, so
1024          * all that is left is pathspecs.
1025          *
1026          * Handle
1027          *
1028          *  1) git checkout <tree> -- [<paths>]
1029          *  2) git checkout -- [<paths>]
1030          *  3) git checkout <something> [<paths>]
1031          *
1032          * including "last branch" syntax and DWIM-ery for names of
1033          * remote branches, erroring out for invalid or ambiguous cases.
1034          */
1035         if (argc) {
1036                 int dwim_ok =
1037                         !patch_mode &&
1038                         dwim_new_local_branch &&
1039                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1040                         !opts.new_branch;
1041                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1042                                 &new, &source_tree, rev, &opts.new_branch);
1043                 argv += n;
1044                 argc -= n;
1045         }
1046
1047         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
1048                 opts.track = git_branch_track;
1049
1050         if (argc) {
1051                 const char **pathspec = get_pathspec(prefix, argv);
1052
1053                 if (!pathspec)
1054                         die(_("invalid path specification"));
1055
1056                 if (patch_mode)
1057                         return interactive_checkout(new.name, pathspec, &opts);
1058
1059                 /* Checkout paths */
1060                 if (opts.new_branch) {
1061                         if (argc == 1) {
1062                                 die(_("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?"), argv[0]);
1063                         } else {
1064                                 die(_("git checkout: updating paths is incompatible with switching branches."));
1065                         }
1066                 }
1067
1068                 if (opts.force_detach)
1069                         die(_("git checkout: --detach does not take a path argument"));
1070
1071                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1072                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index."));
1073
1074                 return checkout_paths(source_tree, pathspec, prefix, &opts);
1075         }
1076
1077         if (patch_mode)
1078                 return interactive_checkout(new.name, NULL, &opts);
1079
1080         if (opts.new_branch) {
1081                 struct strbuf buf = STRBUF_INIT;
1082
1083                 opts.branch_exists = validate_new_branchname(opts.new_branch, &buf,
1084                                                              !!opts.new_branch_force,
1085                                                              !!opts.new_branch_force);
1086
1087                 strbuf_release(&buf);
1088         }
1089
1090         if (new.name && !new.commit) {
1091                 die(_("Cannot switch branch to a non-commit."));
1092         }
1093         if (opts.writeout_stage)
1094                 die(_("--ours/--theirs is incompatible with switching branches."));
1095
1096         if (!new.commit && opts.new_branch) {
1097                 unsigned char rev[20];
1098                 int flag;
1099
1100                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
1101                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1102                         return switch_unborn_to_new_branch(&opts);
1103         }
1104         return switch_branches(&opts, &new);
1105 }