Merge branch 'jc/maint-blame-no-such-path'
[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         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
39         const char *new_branch;
40         const char *new_branch_force;
41         const char *new_orphan_branch;
42         int new_branch_log;
43         enum branch_track track;
44         struct diff_options diff_options;
45
46         int branch_exists;
47         const char *prefix;
48         const char **pathspec;
49         struct tree *source_tree;
50 };
51
52 static int post_checkout_hook(struct commit *old, struct commit *new,
53                               int changed)
54 {
55         return run_hook(NULL, "post-checkout",
56                         sha1_to_hex(old ? old->object.sha1 : null_sha1),
57                         sha1_to_hex(new ? new->object.sha1 : null_sha1),
58                         changed ? "1" : "0", NULL);
59         /* "new" can be NULL when checking out from the index before
60            a commit exists. */
61
62 }
63
64 static int update_some(const unsigned char *sha1, const char *base, int baselen,
65                 const char *pathname, unsigned mode, int stage, void *context)
66 {
67         int len;
68         struct cache_entry *ce;
69
70         if (S_ISDIR(mode))
71                 return READ_TREE_RECURSIVE;
72
73         len = baselen + strlen(pathname);
74         ce = xcalloc(1, cache_entry_size(len));
75         hashcpy(ce->sha1, sha1);
76         memcpy(ce->name, base, baselen);
77         memcpy(ce->name + baselen, pathname, len - baselen);
78         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
79         ce->ce_namelen = len;
80         ce->ce_mode = create_ce_mode(mode);
81         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
82         return 0;
83 }
84
85 static int read_tree_some(struct tree *tree, const char **pathspec)
86 {
87         struct pathspec ps;
88         init_pathspec(&ps, pathspec);
89         read_tree_recursive(tree, "", 0, 0, &ps, update_some, NULL);
90         free_pathspec(&ps);
91
92         /* update the index with the given tree's info
93          * for all args, expanding wildcards, and exit
94          * with any non-zero return code.
95          */
96         return 0;
97 }
98
99 static int skip_same_name(struct cache_entry *ce, int pos)
100 {
101         while (++pos < active_nr &&
102                !strcmp(active_cache[pos]->name, ce->name))
103                 ; /* skip */
104         return pos;
105 }
106
107 static int check_stage(int stage, struct cache_entry *ce, int pos)
108 {
109         while (pos < active_nr &&
110                !strcmp(active_cache[pos]->name, ce->name)) {
111                 if (ce_stage(active_cache[pos]) == stage)
112                         return 0;
113                 pos++;
114         }
115         if (stage == 2)
116                 return error(_("path '%s' does not have our version"), ce->name);
117         else
118                 return error(_("path '%s' does not have their version"), ce->name);
119 }
120
121 static int check_stages(unsigned stages, struct cache_entry *ce, int pos)
122 {
123         unsigned seen = 0;
124         const char *name = ce->name;
125
126         while (pos < active_nr) {
127                 ce = active_cache[pos];
128                 if (strcmp(name, ce->name))
129                         break;
130                 seen |= (1 << ce_stage(ce));
131                 pos++;
132         }
133         if ((stages & seen) != stages)
134                 return error(_("path '%s' does not have all necessary versions"),
135                              name);
136         return 0;
137 }
138
139 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
140                           struct checkout *state)
141 {
142         while (pos < active_nr &&
143                !strcmp(active_cache[pos]->name, ce->name)) {
144                 if (ce_stage(active_cache[pos]) == stage)
145                         return checkout_entry(active_cache[pos], state, NULL);
146                 pos++;
147         }
148         if (stage == 2)
149                 return error(_("path '%s' does not have our version"), ce->name);
150         else
151                 return error(_("path '%s' does not have their version"), ce->name);
152 }
153
154 static int checkout_merged(int pos, struct checkout *state)
155 {
156         struct cache_entry *ce = active_cache[pos];
157         const char *path = ce->name;
158         mmfile_t ancestor, ours, theirs;
159         int status;
160         unsigned char sha1[20];
161         mmbuffer_t result_buf;
162         unsigned char threeway[3][20];
163         unsigned mode = 0;
164
165         memset(threeway, 0, sizeof(threeway));
166         while (pos < active_nr) {
167                 int stage;
168                 stage = ce_stage(ce);
169                 if (!stage || strcmp(path, ce->name))
170                         break;
171                 hashcpy(threeway[stage - 1], ce->sha1);
172                 if (stage == 2)
173                         mode = create_ce_mode(ce->ce_mode);
174                 pos++;
175                 ce = active_cache[pos];
176         }
177         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
178                 return error(_("path '%s' does not have necessary versions"), path);
179
180         read_mmblob(&ancestor, threeway[0]);
181         read_mmblob(&ours, threeway[1]);
182         read_mmblob(&theirs, threeway[2]);
183
184         /*
185          * NEEDSWORK: re-create conflicts from merges with
186          * merge.renormalize set, too
187          */
188         status = ll_merge(&result_buf, path, &ancestor, "base",
189                           &ours, "ours", &theirs, "theirs", NULL);
190         free(ancestor.ptr);
191         free(ours.ptr);
192         free(theirs.ptr);
193         if (status < 0 || !result_buf.ptr) {
194                 free(result_buf.ptr);
195                 return error(_("path '%s': cannot merge"), path);
196         }
197
198         /*
199          * NEEDSWORK:
200          * There is absolutely no reason to write this as a blob object
201          * and create a phony cache entry just to leak.  This hack is
202          * primarily to get to the write_entry() machinery that massages
203          * the contents to work-tree format and writes out which only
204          * allows it for a cache entry.  The code in write_entry() needs
205          * to be refactored to allow us to feed a <buffer, size, mode>
206          * instead of a cache entry.  Such a refactoring would help
207          * merge_recursive as well (it also writes the merge result to the
208          * object database even when it may contain conflicts).
209          */
210         if (write_sha1_file(result_buf.ptr, result_buf.size,
211                             blob_type, sha1))
212                 die(_("Unable to add merge result for '%s'"), path);
213         ce = make_cache_entry(mode, sha1, path, 2, 0);
214         if (!ce)
215                 die(_("make_cache_entry failed for path '%s'"), path);
216         status = checkout_entry(ce, state, NULL);
217         return status;
218 }
219
220 static int checkout_paths(const struct checkout_opts *opts,
221                           const char *revision)
222 {
223         int pos;
224         struct checkout state;
225         static char *ps_matched;
226         unsigned char rev[20];
227         int flag;
228         struct commit *head;
229         int errs = 0;
230         int stage = opts->writeout_stage;
231         int merge = opts->merge;
232         int newfd;
233         struct lock_file *lock_file;
234
235         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
236                 die(_("'%s' cannot be used with updating paths"), "--track");
237
238         if (opts->new_branch_log)
239                 die(_("'%s' cannot be used with updating paths"), "-l");
240
241         if (opts->force && opts->patch_mode)
242                 die(_("'%s' cannot be used with updating paths"), "-f");
243
244         if (opts->force_detach)
245                 die(_("'%s' cannot be used with updating paths"), "--detach");
246
247         if (opts->merge && opts->patch_mode)
248                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
249
250         if (opts->force && opts->merge)
251                 die(_("'%s' cannot be used with %s"), "-f", "-m");
252
253         if (opts->new_branch)
254                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
255                     opts->new_branch);
256
257         if (opts->patch_mode)
258                 return run_add_interactive(revision, "--patch=checkout",
259                                            opts->pathspec);
260
261         lock_file = xcalloc(1, sizeof(struct lock_file));
262
263         newfd = hold_locked_index(lock_file, 1);
264         if (read_cache_preload(opts->pathspec) < 0)
265                 return error(_("corrupt index file"));
266
267         if (opts->source_tree)
268                 read_tree_some(opts->source_tree, opts->pathspec);
269
270         for (pos = 0; opts->pathspec[pos]; pos++)
271                 ;
272         ps_matched = xcalloc(1, pos);
273
274         for (pos = 0; pos < active_nr; pos++) {
275                 struct cache_entry *ce = active_cache[pos];
276                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
277                         continue;
278                 match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
279         }
280
281         if (report_path_error(ps_matched, opts->pathspec, opts->prefix))
282                 return 1;
283
284         /* "checkout -m path" to recreate conflicted state */
285         if (opts->merge)
286                 unmerge_cache(opts->pathspec);
287
288         /* Any unmerged paths? */
289         for (pos = 0; pos < active_nr; pos++) {
290                 struct cache_entry *ce = active_cache[pos];
291                 if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
292                         if (!ce_stage(ce))
293                                 continue;
294                         if (opts->force) {
295                                 warning(_("path '%s' is unmerged"), ce->name);
296                         } else if (stage) {
297                                 errs |= check_stage(stage, ce, pos);
298                         } else if (opts->merge) {
299                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
300                         } else {
301                                 errs = 1;
302                                 error(_("path '%s' is unmerged"), ce->name);
303                         }
304                         pos = skip_same_name(ce, pos) - 1;
305                 }
306         }
307         if (errs)
308                 return 1;
309
310         /* Now we are committed to check them out */
311         memset(&state, 0, sizeof(state));
312         state.force = 1;
313         state.refresh_cache = 1;
314         for (pos = 0; pos < active_nr; pos++) {
315                 struct cache_entry *ce = active_cache[pos];
316                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
317                         continue;
318                 if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
319                         if (!ce_stage(ce)) {
320                                 errs |= checkout_entry(ce, &state, NULL);
321                                 continue;
322                         }
323                         if (stage)
324                                 errs |= checkout_stage(stage, ce, pos, &state);
325                         else if (merge)
326                                 errs |= checkout_merged(pos, &state);
327                         pos = skip_same_name(ce, pos) - 1;
328                 }
329         }
330
331         if (write_cache(newfd, active_cache, active_nr) ||
332             commit_locked_index(lock_file))
333                 die(_("unable to write new index file"));
334
335         read_ref_full("HEAD", rev, 0, &flag);
336         head = lookup_commit_reference_gently(rev, 1);
337
338         errs |= post_checkout_hook(head, head, 0);
339         return errs;
340 }
341
342 static void show_local_changes(struct object *head,
343                                const struct diff_options *opts)
344 {
345         struct rev_info rev;
346         /* I think we want full paths, even if we're in a subdirectory. */
347         init_revisions(&rev, NULL);
348         rev.diffopt.flags = opts->flags;
349         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
350         diff_setup_done(&rev.diffopt);
351         add_pending_object(&rev, head, NULL);
352         run_diff_index(&rev, 0);
353 }
354
355 static void describe_detached_head(const char *msg, struct commit *commit)
356 {
357         struct strbuf sb = STRBUF_INIT;
358         parse_commit(commit);
359         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
360         fprintf(stderr, "%s %s... %s\n", msg,
361                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
362         strbuf_release(&sb);
363 }
364
365 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
366                       int worktree, int *writeout_error)
367 {
368         struct unpack_trees_options opts;
369         struct tree_desc tree_desc;
370
371         memset(&opts, 0, sizeof(opts));
372         opts.head_idx = -1;
373         opts.update = worktree;
374         opts.skip_unmerged = !worktree;
375         opts.reset = 1;
376         opts.merge = 1;
377         opts.fn = oneway_merge;
378         opts.verbose_update = !o->quiet && isatty(2);
379         opts.src_index = &the_index;
380         opts.dst_index = &the_index;
381         parse_tree(tree);
382         init_tree_desc(&tree_desc, tree->buffer, tree->size);
383         switch (unpack_trees(1, &tree_desc, &opts)) {
384         case -2:
385                 *writeout_error = 1;
386                 /*
387                  * We return 0 nevertheless, as the index is all right
388                  * and more importantly we have made best efforts to
389                  * update paths in the work tree, and we cannot revert
390                  * them.
391                  */
392         case 0:
393                 return 0;
394         default:
395                 return 128;
396         }
397 }
398
399 struct branch_info {
400         const char *name; /* The short name used */
401         const char *path; /* The full name of a real branch */
402         struct commit *commit; /* The named commit */
403 };
404
405 static void setup_branch_path(struct branch_info *branch)
406 {
407         struct strbuf buf = STRBUF_INIT;
408
409         strbuf_branchname(&buf, branch->name);
410         if (strcmp(buf.buf, branch->name))
411                 branch->name = xstrdup(buf.buf);
412         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
413         branch->path = strbuf_detach(&buf, NULL);
414 }
415
416 static int merge_working_tree(const struct checkout_opts *opts,
417                               struct branch_info *old,
418                               struct branch_info *new,
419                               int *writeout_error)
420 {
421         int ret;
422         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
423         int newfd = hold_locked_index(lock_file, 1);
424
425         if (read_cache_preload(NULL) < 0)
426                 return error(_("corrupt index file"));
427
428         resolve_undo_clear();
429         if (opts->force) {
430                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
431                 if (ret)
432                         return ret;
433         } else {
434                 struct tree_desc trees[2];
435                 struct tree *tree;
436                 struct unpack_trees_options topts;
437
438                 memset(&topts, 0, sizeof(topts));
439                 topts.head_idx = -1;
440                 topts.src_index = &the_index;
441                 topts.dst_index = &the_index;
442
443                 setup_unpack_trees_porcelain(&topts, "checkout");
444
445                 refresh_cache(REFRESH_QUIET);
446
447                 if (unmerged_cache()) {
448                         error(_("you need to resolve your current index first"));
449                         return 1;
450                 }
451
452                 /* 2-way merge to the new branch */
453                 topts.initial_checkout = is_cache_unborn();
454                 topts.update = 1;
455                 topts.merge = 1;
456                 topts.gently = opts->merge && old->commit;
457                 topts.verbose_update = !opts->quiet && isatty(2);
458                 topts.fn = twoway_merge;
459                 if (opts->overwrite_ignore) {
460                         topts.dir = xcalloc(1, sizeof(*topts.dir));
461                         topts.dir->flags |= DIR_SHOW_IGNORED;
462                         setup_standard_excludes(topts.dir);
463                 }
464                 tree = parse_tree_indirect(old->commit ?
465                                            old->commit->object.sha1 :
466                                            EMPTY_TREE_SHA1_BIN);
467                 init_tree_desc(&trees[0], tree->buffer, tree->size);
468                 tree = parse_tree_indirect(new->commit->object.sha1);
469                 init_tree_desc(&trees[1], tree->buffer, tree->size);
470
471                 ret = unpack_trees(2, trees, &topts);
472                 if (ret == -1) {
473                         /*
474                          * Unpack couldn't do a trivial merge; either
475                          * give up or do a real merge, depending on
476                          * whether the merge flag was used.
477                          */
478                         struct tree *result;
479                         struct tree *work;
480                         struct merge_options o;
481                         if (!opts->merge)
482                                 return 1;
483
484                         /*
485                          * Without old->commit, the below is the same as
486                          * the two-tree unpack we already tried and failed.
487                          */
488                         if (!old->commit)
489                                 return 1;
490
491                         /* Do more real merge */
492
493                         /*
494                          * We update the index fully, then write the
495                          * tree from the index, then merge the new
496                          * branch with the current tree, with the old
497                          * branch as the base. Then we reset the index
498                          * (but not the working tree) to the new
499                          * branch, leaving the working tree as the
500                          * merged version, but skipping unmerged
501                          * entries in the index.
502                          */
503
504                         add_files_to_cache(NULL, NULL, 0);
505                         /*
506                          * NEEDSWORK: carrying over local changes
507                          * when branches have different end-of-line
508                          * normalization (or clean+smudge rules) is
509                          * a pain; plumb in an option to set
510                          * o.renormalize?
511                          */
512                         init_merge_options(&o);
513                         o.verbosity = 0;
514                         work = write_tree_from_memory(&o);
515
516                         ret = reset_tree(new->commit->tree, opts, 1,
517                                          writeout_error);
518                         if (ret)
519                                 return ret;
520                         o.ancestor = old->name;
521                         o.branch1 = new->name;
522                         o.branch2 = "local";
523                         merge_trees(&o, new->commit->tree, work,
524                                 old->commit->tree, &result);
525                         ret = reset_tree(new->commit->tree, opts, 0,
526                                          writeout_error);
527                         if (ret)
528                                 return ret;
529                 }
530         }
531
532         if (write_cache(newfd, active_cache, active_nr) ||
533             commit_locked_index(lock_file))
534                 die(_("unable to write new index file"));
535
536         if (!opts->force && !opts->quiet)
537                 show_local_changes(&new->commit->object, &opts->diff_options);
538
539         return 0;
540 }
541
542 static void report_tracking(struct branch_info *new)
543 {
544         struct strbuf sb = STRBUF_INIT;
545         struct branch *branch = branch_get(new->name);
546
547         if (!format_tracking_info(branch, &sb))
548                 return;
549         fputs(sb.buf, stdout);
550         strbuf_release(&sb);
551 }
552
553 static void update_refs_for_switch(const struct checkout_opts *opts,
554                                    struct branch_info *old,
555                                    struct branch_info *new)
556 {
557         struct strbuf msg = STRBUF_INIT;
558         const char *old_desc;
559         if (opts->new_branch) {
560                 if (opts->new_orphan_branch) {
561                         if (opts->new_branch_log && !log_all_ref_updates) {
562                                 int temp;
563                                 char log_file[PATH_MAX];
564                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
565
566                                 temp = log_all_ref_updates;
567                                 log_all_ref_updates = 1;
568                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
569                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
570                                             opts->new_orphan_branch);
571                                         log_all_ref_updates = temp;
572                                         return;
573                                 }
574                                 log_all_ref_updates = temp;
575                         }
576                 }
577                 else
578                         create_branch(old->name, opts->new_branch, new->name,
579                                       opts->new_branch_force ? 1 : 0,
580                                       opts->new_branch_log,
581                                       opts->new_branch_force ? 1 : 0,
582                                       opts->quiet,
583                                       opts->track);
584                 new->name = opts->new_branch;
585                 setup_branch_path(new);
586         }
587
588         old_desc = old->name;
589         if (!old_desc && old->commit)
590                 old_desc = sha1_to_hex(old->commit->object.sha1);
591         strbuf_addf(&msg, "checkout: moving from %s to %s",
592                     old_desc ? old_desc : "(invalid)", new->name);
593
594         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
595                 /* Nothing to do. */
596         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
597                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
598                            REF_NODEREF, DIE_ON_ERR);
599                 if (!opts->quiet) {
600                         if (old->path && advice_detached_head)
601                                 detach_advice(new->name);
602                         describe_detached_head(_("HEAD is now at"), new->commit);
603                 }
604         } else if (new->path) { /* Switch branches. */
605                 create_symref("HEAD", new->path, msg.buf);
606                 if (!opts->quiet) {
607                         if (old->path && !strcmp(new->path, old->path)) {
608                                 if (opts->new_branch_force)
609                                         fprintf(stderr, _("Reset branch '%s'\n"),
610                                                 new->name);
611                                 else
612                                         fprintf(stderr, _("Already on '%s'\n"),
613                                                 new->name);
614                         } else if (opts->new_branch) {
615                                 if (opts->branch_exists)
616                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
617                                 else
618                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
619                         } else {
620                                 fprintf(stderr, _("Switched to branch '%s'\n"),
621                                         new->name);
622                         }
623                 }
624                 if (old->path && old->name) {
625                         char log_file[PATH_MAX], ref_file[PATH_MAX];
626
627                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
628                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
629                         if (!file_exists(ref_file) && file_exists(log_file))
630                                 remove_path(log_file);
631                 }
632         }
633         remove_branch_state();
634         strbuf_release(&msg);
635         if (!opts->quiet &&
636             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
637                 report_tracking(new);
638 }
639
640 static int add_pending_uninteresting_ref(const char *refname,
641                                          const unsigned char *sha1,
642                                          int flags, void *cb_data)
643 {
644         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
645         return 0;
646 }
647
648 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
649 {
650         parse_commit(commit);
651         strbuf_addstr(sb, "  ");
652         strbuf_addstr(sb,
653                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
654         strbuf_addch(sb, ' ');
655         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
656         strbuf_addch(sb, '\n');
657 }
658
659 #define ORPHAN_CUTOFF 4
660 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
661 {
662         struct commit *c, *last = NULL;
663         struct strbuf sb = STRBUF_INIT;
664         int lost = 0;
665         while ((c = get_revision(revs)) != NULL) {
666                 if (lost < ORPHAN_CUTOFF)
667                         describe_one_orphan(&sb, c);
668                 last = c;
669                 lost++;
670         }
671         if (ORPHAN_CUTOFF < lost) {
672                 int more = lost - ORPHAN_CUTOFF;
673                 if (more == 1)
674                         describe_one_orphan(&sb, last);
675                 else
676                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
677         }
678
679         fprintf(stderr,
680                 Q_(
681                 /* The singular version */
682                 "Warning: you are leaving %d commit behind, "
683                 "not connected to\n"
684                 "any of your branches:\n\n"
685                 "%s\n",
686                 /* The plural version */
687                 "Warning: you are leaving %d commits behind, "
688                 "not connected to\n"
689                 "any of your branches:\n\n"
690                 "%s\n",
691                 /* Give ngettext() the count */
692                 lost),
693                 lost,
694                 sb.buf);
695         strbuf_release(&sb);
696
697         if (advice_detached_head)
698                 fprintf(stderr,
699                         _(
700                         "If you want to keep them by creating a new branch, "
701                         "this may be a good time\nto do so with:\n\n"
702                         " git branch new_branch_name %s\n\n"),
703                         sha1_to_hex(commit->object.sha1));
704 }
705
706 /*
707  * We are about to leave commit that was at the tip of a detached
708  * HEAD.  If it is not reachable from any ref, this is the last chance
709  * for the user to do so without resorting to reflog.
710  */
711 static void orphaned_commit_warning(struct commit *old, struct commit *new)
712 {
713         struct rev_info revs;
714         struct object *object = &old->object;
715         struct object_array refs;
716
717         init_revisions(&revs, NULL);
718         setup_revisions(0, NULL, &revs, NULL);
719
720         object->flags &= ~UNINTERESTING;
721         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
722
723         for_each_ref(add_pending_uninteresting_ref, &revs);
724         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
725
726         refs = revs.pending;
727         revs.leak_pending = 1;
728
729         if (prepare_revision_walk(&revs))
730                 die(_("internal error in revision walk"));
731         if (!(old->object.flags & UNINTERESTING))
732                 suggest_reattach(old, &revs);
733         else
734                 describe_detached_head(_("Previous HEAD position was"), old);
735
736         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
737         free(refs.objects);
738 }
739
740 static int switch_branches(const struct checkout_opts *opts,
741                            struct branch_info *new)
742 {
743         int ret = 0;
744         struct branch_info old;
745         void *path_to_free;
746         unsigned char rev[20];
747         int flag, writeout_error = 0;
748         memset(&old, 0, sizeof(old));
749         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
750         old.commit = lookup_commit_reference_gently(rev, 1);
751         if (!(flag & REF_ISSYMREF))
752                 old.path = NULL;
753
754         if (old.path && !prefixcmp(old.path, "refs/heads/"))
755                 old.name = old.path + strlen("refs/heads/");
756
757         if (!new->name) {
758                 new->name = "HEAD";
759                 new->commit = old.commit;
760                 if (!new->commit)
761                         die(_("You are on a branch yet to be born"));
762                 parse_commit(new->commit);
763         }
764
765         ret = merge_working_tree(opts, &old, new, &writeout_error);
766         if (ret) {
767                 free(path_to_free);
768                 return ret;
769         }
770
771         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
772                 orphaned_commit_warning(old.commit, new->commit);
773
774         update_refs_for_switch(opts, &old, new);
775
776         ret = post_checkout_hook(old.commit, new->commit, 1);
777         free(path_to_free);
778         return ret || writeout_error;
779 }
780
781 static int git_checkout_config(const char *var, const char *value, void *cb)
782 {
783         if (!strcmp(var, "diff.ignoresubmodules")) {
784                 struct checkout_opts *opts = cb;
785                 handle_ignore_submodules_arg(&opts->diff_options, value);
786                 return 0;
787         }
788
789         if (!prefixcmp(var, "submodule."))
790                 return parse_submodule_config_option(var, value);
791
792         return git_xmerge_config(var, value, NULL);
793 }
794
795 struct tracking_name_data {
796         const char *name;
797         char *remote;
798         int unique;
799 };
800
801 static int check_tracking_name(const char *refname, const unsigned char *sha1,
802                                int flags, void *cb_data)
803 {
804         struct tracking_name_data *cb = cb_data;
805         const char *slash;
806
807         if (prefixcmp(refname, "refs/remotes/"))
808                 return 0;
809         slash = strchr(refname + 13, '/');
810         if (!slash || strcmp(slash + 1, cb->name))
811                 return 0;
812         if (cb->remote) {
813                 cb->unique = 0;
814                 return 0;
815         }
816         cb->remote = xstrdup(refname);
817         return 0;
818 }
819
820 static const char *unique_tracking_name(const char *name)
821 {
822         struct tracking_name_data cb_data = { NULL, NULL, 1 };
823         cb_data.name = name;
824         for_each_ref(check_tracking_name, &cb_data);
825         if (cb_data.unique)
826                 return cb_data.remote;
827         free(cb_data.remote);
828         return NULL;
829 }
830
831 static int parse_branchname_arg(int argc, const char **argv,
832                                 int dwim_new_local_branch_ok,
833                                 struct branch_info *new,
834                                 struct tree **source_tree,
835                                 unsigned char rev[20],
836                                 const char **new_branch)
837 {
838         int argcount = 0;
839         unsigned char branch_rev[20];
840         const char *arg;
841         int has_dash_dash;
842
843         /*
844          * case 1: git checkout <ref> -- [<paths>]
845          *
846          *   <ref> must be a valid tree, everything after the '--' must be
847          *   a path.
848          *
849          * case 2: git checkout -- [<paths>]
850          *
851          *   everything after the '--' must be paths.
852          *
853          * case 3: git checkout <something> [<paths>]
854          *
855          *   With no paths, if <something> is a commit, that is to
856          *   switch to the branch or detach HEAD at it.  As a special case,
857          *   if <something> is A...B (missing A or B means HEAD but you can
858          *   omit at most one side), and if there is a unique merge base
859          *   between A and B, A...B names that merge base.
860          *
861          *   With no paths, if <something> is _not_ a commit, no -t nor -b
862          *   was given, and there is a tracking branch whose name is
863          *   <something> in one and only one remote, then this is a short-hand
864          *   to fork local <something> from that remote-tracking branch.
865          *
866          *   Otherwise <something> shall not be ambiguous.
867          *   - If it's *only* a reference, treat it like case (1).
868          *   - If it's only a path, treat it like case (2).
869          *   - else: fail.
870          *
871          */
872         if (!argc)
873                 return 0;
874
875         if (!strcmp(argv[0], "--"))     /* case (2) */
876                 return 1;
877
878         arg = argv[0];
879         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
880
881         if (!strcmp(arg, "-"))
882                 arg = "@{-1}";
883
884         if (get_sha1_mb(arg, rev)) {
885                 if (has_dash_dash)          /* case (1) */
886                         die(_("invalid reference: %s"), arg);
887                 if (dwim_new_local_branch_ok &&
888                     !check_filename(NULL, arg) &&
889                     argc == 1) {
890                         const char *remote = unique_tracking_name(arg);
891                         if (!remote || get_sha1(remote, rev))
892                                 return argcount;
893                         *new_branch = arg;
894                         arg = remote;
895                         /* DWIMmed to create local branch */
896                 } else {
897                         return argcount;
898                 }
899         }
900
901         /* we can't end up being in (2) anymore, eat the argument */
902         argcount++;
903         argv++;
904         argc--;
905
906         new->name = arg;
907         setup_branch_path(new);
908
909         if (!check_refname_format(new->path, 0) &&
910             !read_ref(new->path, branch_rev))
911                 hashcpy(rev, branch_rev);
912         else
913                 new->path = NULL; /* not an existing branch */
914
915         new->commit = lookup_commit_reference_gently(rev, 1);
916         if (!new->commit) {
917                 /* not a commit */
918                 *source_tree = parse_tree_indirect(rev);
919         } else {
920                 parse_commit(new->commit);
921                 *source_tree = new->commit->tree;
922         }
923
924         if (!*source_tree)                   /* case (1): want a tree */
925                 die(_("reference is not a tree: %s"), arg);
926         if (!has_dash_dash) {/* case (3 -> 1) */
927                 /*
928                  * Do not complain the most common case
929                  *      git checkout branch
930                  * even if there happen to be a file called 'branch';
931                  * it would be extremely annoying.
932                  */
933                 if (argc)
934                         verify_non_filename(NULL, arg);
935         } else {
936                 argcount++;
937                 argv++;
938                 argc--;
939         }
940
941         return argcount;
942 }
943
944 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
945 {
946         int status;
947         struct strbuf branch_ref = STRBUF_INIT;
948
949         if (!opts->new_branch)
950                 die(_("You are on a branch yet to be born"));
951         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
952         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
953         strbuf_release(&branch_ref);
954         return status;
955 }
956
957 static int checkout_branch(struct checkout_opts *opts,
958                            struct branch_info *new)
959 {
960         if (opts->pathspec)
961                 die(_("paths cannot be used with switching branches"));
962
963         if (opts->patch_mode)
964                 die(_("'%s' cannot be used with switching branches"),
965                     "--patch");
966
967         if (opts->writeout_stage)
968                 die(_("'%s' cannot be used with switching branches"),
969                     "--ours/--theirs");
970
971         if (opts->force && opts->merge)
972                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
973
974         if (opts->force_detach && opts->new_branch)
975                 die(_("'%s' cannot be used with '%s'"),
976                     "--detach", "-b/-B/--orphan");
977
978         if (opts->new_orphan_branch) {
979                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
980                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
981         } else if (opts->force_detach) {
982                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
983                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
984         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
985                 opts->track = git_branch_track;
986
987         if (new->name && !new->commit)
988                 die(_("Cannot switch branch to a non-commit '%s'"),
989                     new->name);
990
991         if (!new->commit && opts->new_branch) {
992                 unsigned char rev[20];
993                 int flag;
994
995                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
996                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
997                         return switch_unborn_to_new_branch(opts);
998         }
999         return switch_branches(opts, new);
1000 }
1001
1002 int cmd_checkout(int argc, const char **argv, const char *prefix)
1003 {
1004         struct checkout_opts opts;
1005         struct branch_info new;
1006         char *conflict_style = NULL;
1007         int dwim_new_local_branch = 1;
1008         struct option options[] = {
1009                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1010                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1011                            N_("create and checkout a new branch")),
1012                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1013                            N_("create/reset and checkout a branch")),
1014                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1015                 OPT_BOOLEAN(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1016                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1017                         BRANCH_TRACK_EXPLICIT),
1018                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new branch"), N_("new unparented branch")),
1019                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1020                             2),
1021                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1022                             3),
1023                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1024                 OPT_BOOLEAN('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1025                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1026                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1027                            N_("conflict style (merge or diff3)")),
1028                 OPT_BOOLEAN('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1029                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
1030                   N_("second guess 'git checkout no-such-branch'"),
1031                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
1032                 OPT_END(),
1033         };
1034
1035         memset(&opts, 0, sizeof(opts));
1036         memset(&new, 0, sizeof(new));
1037         opts.overwrite_ignore = 1;
1038         opts.prefix = prefix;
1039
1040         gitmodules_config();
1041         git_config(git_checkout_config, &opts);
1042
1043         opts.track = BRANCH_TRACK_UNSPECIFIED;
1044
1045         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1046                              PARSE_OPT_KEEP_DASHDASH);
1047
1048         if (conflict_style) {
1049                 opts.merge = 1; /* implied */
1050                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1051         }
1052
1053         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1054                 die(_("-b, -B and --orphan are mutually exclusive"));
1055
1056         /*
1057          * From here on, new_branch will contain the branch to be checked out,
1058          * and new_branch_force and new_orphan_branch will tell us which one of
1059          * -b/-B/--orphan is being used.
1060          */
1061         if (opts.new_branch_force)
1062                 opts.new_branch = opts.new_branch_force;
1063
1064         if (opts.new_orphan_branch)
1065                 opts.new_branch = opts.new_orphan_branch;
1066
1067         /* --track without -b/-B/--orphan should DWIM */
1068         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1069                 const char *argv0 = argv[0];
1070                 if (!argc || !strcmp(argv0, "--"))
1071                         die (_("--track needs a branch name"));
1072                 if (!prefixcmp(argv0, "refs/"))
1073                         argv0 += 5;
1074                 if (!prefixcmp(argv0, "remotes/"))
1075                         argv0 += 8;
1076                 argv0 = strchr(argv0, '/');
1077                 if (!argv0 || !argv0[1])
1078                         die (_("Missing branch name; try -b"));
1079                 opts.new_branch = argv0 + 1;
1080         }
1081
1082         /*
1083          * Extract branch name from command line arguments, so
1084          * all that is left is pathspecs.
1085          *
1086          * Handle
1087          *
1088          *  1) git checkout <tree> -- [<paths>]
1089          *  2) git checkout -- [<paths>]
1090          *  3) git checkout <something> [<paths>]
1091          *
1092          * including "last branch" syntax and DWIM-ery for names of
1093          * remote branches, erroring out for invalid or ambiguous cases.
1094          */
1095         if (argc) {
1096                 unsigned char rev[20];
1097                 int dwim_ok =
1098                         !opts.patch_mode &&
1099                         dwim_new_local_branch &&
1100                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1101                         !opts.new_branch;
1102                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1103                                              &new, &opts.source_tree,
1104                                              rev, &opts.new_branch);
1105                 argv += n;
1106                 argc -= n;
1107         }
1108
1109         if (argc) {
1110                 opts.pathspec = get_pathspec(prefix, argv);
1111
1112                 if (!opts.pathspec)
1113                         die(_("invalid path specification"));
1114
1115                 /*
1116                  * Try to give more helpful suggestion.
1117                  * new_branch && argc > 1 will be caught later.
1118                  */
1119                 if (opts.new_branch && argc == 1)
1120                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1121                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1122                             opts.new_branch, argv[0]);
1123
1124                 if (opts.force_detach)
1125                         die(_("git checkout: --detach does not take a path argument '%s'"),
1126                             argv[0]);
1127
1128                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1129                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1130                               "checking out of the index."));
1131         }
1132
1133         if (opts.new_branch) {
1134                 struct strbuf buf = STRBUF_INIT;
1135
1136                 opts.branch_exists =
1137                         validate_new_branchname(opts.new_branch, &buf,
1138                                                 !!opts.new_branch_force,
1139                                                 !!opts.new_branch_force);
1140
1141                 strbuf_release(&buf);
1142         }
1143
1144         if (opts.patch_mode || opts.pathspec)
1145                 return checkout_paths(&opts, new.name);
1146         else
1147                 return checkout_branch(&opts, &new);
1148 }