Merge branch 'rs/submodule-summary-limit'
[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         /*
275          * Make sure all pathspecs participated in locating the paths
276          * to be checked out.
277          */
278         for (pos = 0; pos < active_nr; pos++) {
279                 struct cache_entry *ce = active_cache[pos];
280                 ce->ce_flags &= ~CE_MATCHED;
281                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
282                         /*
283                          * "git checkout tree-ish -- path", but this entry
284                          * is in the original index; it will not be checked
285                          * out to the working tree and it does not matter
286                          * if pathspec matched this entry.  We will not do
287                          * anything to this entry at all.
288                          */
289                         continue;
290                 /*
291                  * Either this entry came from the tree-ish we are
292                  * checking the paths out of, or we are checking out
293                  * of the index.
294                  *
295                  * If it comes from the tree-ish, we already know it
296                  * matches the pathspec and could just stamp
297                  * CE_MATCHED to it from update_some(). But we still
298                  * need ps_matched and read_tree_recursive (and
299                  * eventually tree_entry_interesting) cannot fill
300                  * ps_matched yet. Once it can, we can avoid calling
301                  * match_pathspec() for _all_ entries when
302                  * opts->source_tree != NULL.
303                  */
304                 if (match_pathspec(opts->pathspec, ce->name, ce_namelen(ce),
305                                    0, ps_matched))
306                         ce->ce_flags |= CE_MATCHED;
307         }
308
309         if (report_path_error(ps_matched, opts->pathspec, opts->prefix)) {
310                 free(ps_matched);
311                 return 1;
312         }
313         free(ps_matched);
314
315         /* "checkout -m path" to recreate conflicted state */
316         if (opts->merge)
317                 unmerge_marked_index(&the_index);
318
319         /* Any unmerged paths? */
320         for (pos = 0; pos < active_nr; pos++) {
321                 struct cache_entry *ce = active_cache[pos];
322                 if (ce->ce_flags & CE_MATCHED) {
323                         if (!ce_stage(ce))
324                                 continue;
325                         if (opts->force) {
326                                 warning(_("path '%s' is unmerged"), ce->name);
327                         } else if (stage) {
328                                 errs |= check_stage(stage, ce, pos);
329                         } else if (opts->merge) {
330                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
331                         } else {
332                                 errs = 1;
333                                 error(_("path '%s' is unmerged"), ce->name);
334                         }
335                         pos = skip_same_name(ce, pos) - 1;
336                 }
337         }
338         if (errs)
339                 return 1;
340
341         /* Now we are committed to check them out */
342         memset(&state, 0, sizeof(state));
343         state.force = 1;
344         state.refresh_cache = 1;
345         for (pos = 0; pos < active_nr; pos++) {
346                 struct cache_entry *ce = active_cache[pos];
347                 if (ce->ce_flags & CE_MATCHED) {
348                         if (!ce_stage(ce)) {
349                                 errs |= checkout_entry(ce, &state, NULL);
350                                 continue;
351                         }
352                         if (stage)
353                                 errs |= checkout_stage(stage, ce, pos, &state);
354                         else if (merge)
355                                 errs |= checkout_merged(pos, &state);
356                         pos = skip_same_name(ce, pos) - 1;
357                 }
358         }
359
360         if (write_cache(newfd, active_cache, active_nr) ||
361             commit_locked_index(lock_file))
362                 die(_("unable to write new index file"));
363
364         read_ref_full("HEAD", rev, 0, &flag);
365         head = lookup_commit_reference_gently(rev, 1);
366
367         errs |= post_checkout_hook(head, head, 0);
368         return errs;
369 }
370
371 static void show_local_changes(struct object *head,
372                                const struct diff_options *opts)
373 {
374         struct rev_info rev;
375         /* I think we want full paths, even if we're in a subdirectory. */
376         init_revisions(&rev, NULL);
377         rev.diffopt.flags = opts->flags;
378         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
379         diff_setup_done(&rev.diffopt);
380         add_pending_object(&rev, head, NULL);
381         run_diff_index(&rev, 0);
382 }
383
384 static void describe_detached_head(const char *msg, struct commit *commit)
385 {
386         struct strbuf sb = STRBUF_INIT;
387         parse_commit(commit);
388         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
389         fprintf(stderr, "%s %s... %s\n", msg,
390                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
391         strbuf_release(&sb);
392 }
393
394 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
395                       int worktree, int *writeout_error)
396 {
397         struct unpack_trees_options opts;
398         struct tree_desc tree_desc;
399
400         memset(&opts, 0, sizeof(opts));
401         opts.head_idx = -1;
402         opts.update = worktree;
403         opts.skip_unmerged = !worktree;
404         opts.reset = 1;
405         opts.merge = 1;
406         opts.fn = oneway_merge;
407         opts.verbose_update = !o->quiet && isatty(2);
408         opts.src_index = &the_index;
409         opts.dst_index = &the_index;
410         parse_tree(tree);
411         init_tree_desc(&tree_desc, tree->buffer, tree->size);
412         switch (unpack_trees(1, &tree_desc, &opts)) {
413         case -2:
414                 *writeout_error = 1;
415                 /*
416                  * We return 0 nevertheless, as the index is all right
417                  * and more importantly we have made best efforts to
418                  * update paths in the work tree, and we cannot revert
419                  * them.
420                  */
421         case 0:
422                 return 0;
423         default:
424                 return 128;
425         }
426 }
427
428 struct branch_info {
429         const char *name; /* The short name used */
430         const char *path; /* The full name of a real branch */
431         struct commit *commit; /* The named commit */
432 };
433
434 static void setup_branch_path(struct branch_info *branch)
435 {
436         struct strbuf buf = STRBUF_INIT;
437
438         strbuf_branchname(&buf, branch->name);
439         if (strcmp(buf.buf, branch->name))
440                 branch->name = xstrdup(buf.buf);
441         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
442         branch->path = strbuf_detach(&buf, NULL);
443 }
444
445 static int merge_working_tree(const struct checkout_opts *opts,
446                               struct branch_info *old,
447                               struct branch_info *new,
448                               int *writeout_error)
449 {
450         int ret;
451         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
452         int newfd = hold_locked_index(lock_file, 1);
453
454         if (read_cache_preload(NULL) < 0)
455                 return error(_("corrupt index file"));
456
457         resolve_undo_clear();
458         if (opts->force) {
459                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
460                 if (ret)
461                         return ret;
462         } else {
463                 struct tree_desc trees[2];
464                 struct tree *tree;
465                 struct unpack_trees_options topts;
466
467                 memset(&topts, 0, sizeof(topts));
468                 topts.head_idx = -1;
469                 topts.src_index = &the_index;
470                 topts.dst_index = &the_index;
471
472                 setup_unpack_trees_porcelain(&topts, "checkout");
473
474                 refresh_cache(REFRESH_QUIET);
475
476                 if (unmerged_cache()) {
477                         error(_("you need to resolve your current index first"));
478                         return 1;
479                 }
480
481                 /* 2-way merge to the new branch */
482                 topts.initial_checkout = is_cache_unborn();
483                 topts.update = 1;
484                 topts.merge = 1;
485                 topts.gently = opts->merge && old->commit;
486                 topts.verbose_update = !opts->quiet && isatty(2);
487                 topts.fn = twoway_merge;
488                 if (opts->overwrite_ignore) {
489                         topts.dir = xcalloc(1, sizeof(*topts.dir));
490                         topts.dir->flags |= DIR_SHOW_IGNORED;
491                         setup_standard_excludes(topts.dir);
492                 }
493                 tree = parse_tree_indirect(old->commit ?
494                                            old->commit->object.sha1 :
495                                            EMPTY_TREE_SHA1_BIN);
496                 init_tree_desc(&trees[0], tree->buffer, tree->size);
497                 tree = parse_tree_indirect(new->commit->object.sha1);
498                 init_tree_desc(&trees[1], tree->buffer, tree->size);
499
500                 ret = unpack_trees(2, trees, &topts);
501                 if (ret == -1) {
502                         /*
503                          * Unpack couldn't do a trivial merge; either
504                          * give up or do a real merge, depending on
505                          * whether the merge flag was used.
506                          */
507                         struct tree *result;
508                         struct tree *work;
509                         struct merge_options o;
510                         if (!opts->merge)
511                                 return 1;
512
513                         /*
514                          * Without old->commit, the below is the same as
515                          * the two-tree unpack we already tried and failed.
516                          */
517                         if (!old->commit)
518                                 return 1;
519
520                         /* Do more real merge */
521
522                         /*
523                          * We update the index fully, then write the
524                          * tree from the index, then merge the new
525                          * branch with the current tree, with the old
526                          * branch as the base. Then we reset the index
527                          * (but not the working tree) to the new
528                          * branch, leaving the working tree as the
529                          * merged version, but skipping unmerged
530                          * entries in the index.
531                          */
532
533                         add_files_to_cache(NULL, NULL, 0);
534                         /*
535                          * NEEDSWORK: carrying over local changes
536                          * when branches have different end-of-line
537                          * normalization (or clean+smudge rules) is
538                          * a pain; plumb in an option to set
539                          * o.renormalize?
540                          */
541                         init_merge_options(&o);
542                         o.verbosity = 0;
543                         work = write_tree_from_memory(&o);
544
545                         ret = reset_tree(new->commit->tree, opts, 1,
546                                          writeout_error);
547                         if (ret)
548                                 return ret;
549                         o.ancestor = old->name;
550                         o.branch1 = new->name;
551                         o.branch2 = "local";
552                         merge_trees(&o, new->commit->tree, work,
553                                 old->commit->tree, &result);
554                         ret = reset_tree(new->commit->tree, opts, 0,
555                                          writeout_error);
556                         if (ret)
557                                 return ret;
558                 }
559         }
560
561         if (write_cache(newfd, active_cache, active_nr) ||
562             commit_locked_index(lock_file))
563                 die(_("unable to write new index file"));
564
565         if (!opts->force && !opts->quiet)
566                 show_local_changes(&new->commit->object, &opts->diff_options);
567
568         return 0;
569 }
570
571 static void report_tracking(struct branch_info *new)
572 {
573         struct strbuf sb = STRBUF_INIT;
574         struct branch *branch = branch_get(new->name);
575
576         if (!format_tracking_info(branch, &sb))
577                 return;
578         fputs(sb.buf, stdout);
579         strbuf_release(&sb);
580 }
581
582 static void update_refs_for_switch(const struct checkout_opts *opts,
583                                    struct branch_info *old,
584                                    struct branch_info *new)
585 {
586         struct strbuf msg = STRBUF_INIT;
587         const char *old_desc;
588         if (opts->new_branch) {
589                 if (opts->new_orphan_branch) {
590                         if (opts->new_branch_log && !log_all_ref_updates) {
591                                 int temp;
592                                 char log_file[PATH_MAX];
593                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
594
595                                 temp = log_all_ref_updates;
596                                 log_all_ref_updates = 1;
597                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
598                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
599                                             opts->new_orphan_branch);
600                                         log_all_ref_updates = temp;
601                                         return;
602                                 }
603                                 log_all_ref_updates = temp;
604                         }
605                 }
606                 else
607                         create_branch(old->name, opts->new_branch, new->name,
608                                       opts->new_branch_force ? 1 : 0,
609                                       opts->new_branch_log,
610                                       opts->new_branch_force ? 1 : 0,
611                                       opts->quiet,
612                                       opts->track);
613                 new->name = opts->new_branch;
614                 setup_branch_path(new);
615         }
616
617         old_desc = old->name;
618         if (!old_desc && old->commit)
619                 old_desc = sha1_to_hex(old->commit->object.sha1);
620         strbuf_addf(&msg, "checkout: moving from %s to %s",
621                     old_desc ? old_desc : "(invalid)", new->name);
622
623         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
624                 /* Nothing to do. */
625         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
626                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
627                            REF_NODEREF, DIE_ON_ERR);
628                 if (!opts->quiet) {
629                         if (old->path && advice_detached_head)
630                                 detach_advice(new->name);
631                         describe_detached_head(_("HEAD is now at"), new->commit);
632                 }
633         } else if (new->path) { /* Switch branches. */
634                 create_symref("HEAD", new->path, msg.buf);
635                 if (!opts->quiet) {
636                         if (old->path && !strcmp(new->path, old->path)) {
637                                 if (opts->new_branch_force)
638                                         fprintf(stderr, _("Reset branch '%s'\n"),
639                                                 new->name);
640                                 else
641                                         fprintf(stderr, _("Already on '%s'\n"),
642                                                 new->name);
643                         } else if (opts->new_branch) {
644                                 if (opts->branch_exists)
645                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
646                                 else
647                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
648                         } else {
649                                 fprintf(stderr, _("Switched to branch '%s'\n"),
650                                         new->name);
651                         }
652                 }
653                 if (old->path && old->name) {
654                         char log_file[PATH_MAX], ref_file[PATH_MAX];
655
656                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
657                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
658                         if (!file_exists(ref_file) && file_exists(log_file))
659                                 remove_path(log_file);
660                 }
661         }
662         remove_branch_state();
663         strbuf_release(&msg);
664         if (!opts->quiet &&
665             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
666                 report_tracking(new);
667 }
668
669 static int add_pending_uninteresting_ref(const char *refname,
670                                          const unsigned char *sha1,
671                                          int flags, void *cb_data)
672 {
673         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
674         return 0;
675 }
676
677 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
678 {
679         parse_commit(commit);
680         strbuf_addstr(sb, "  ");
681         strbuf_addstr(sb,
682                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
683         strbuf_addch(sb, ' ');
684         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
685         strbuf_addch(sb, '\n');
686 }
687
688 #define ORPHAN_CUTOFF 4
689 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
690 {
691         struct commit *c, *last = NULL;
692         struct strbuf sb = STRBUF_INIT;
693         int lost = 0;
694         while ((c = get_revision(revs)) != NULL) {
695                 if (lost < ORPHAN_CUTOFF)
696                         describe_one_orphan(&sb, c);
697                 last = c;
698                 lost++;
699         }
700         if (ORPHAN_CUTOFF < lost) {
701                 int more = lost - ORPHAN_CUTOFF;
702                 if (more == 1)
703                         describe_one_orphan(&sb, last);
704                 else
705                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
706         }
707
708         fprintf(stderr,
709                 Q_(
710                 /* The singular version */
711                 "Warning: you are leaving %d commit behind, "
712                 "not connected to\n"
713                 "any of your branches:\n\n"
714                 "%s\n",
715                 /* The plural version */
716                 "Warning: you are leaving %d commits behind, "
717                 "not connected to\n"
718                 "any of your branches:\n\n"
719                 "%s\n",
720                 /* Give ngettext() the count */
721                 lost),
722                 lost,
723                 sb.buf);
724         strbuf_release(&sb);
725
726         if (advice_detached_head)
727                 fprintf(stderr,
728                         _(
729                         "If you want to keep them by creating a new branch, "
730                         "this may be a good time\nto do so with:\n\n"
731                         " git branch new_branch_name %s\n\n"),
732                         sha1_to_hex(commit->object.sha1));
733 }
734
735 /*
736  * We are about to leave commit that was at the tip of a detached
737  * HEAD.  If it is not reachable from any ref, this is the last chance
738  * for the user to do so without resorting to reflog.
739  */
740 static void orphaned_commit_warning(struct commit *old, struct commit *new)
741 {
742         struct rev_info revs;
743         struct object *object = &old->object;
744         struct object_array refs;
745
746         init_revisions(&revs, NULL);
747         setup_revisions(0, NULL, &revs, NULL);
748
749         object->flags &= ~UNINTERESTING;
750         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
751
752         for_each_ref(add_pending_uninteresting_ref, &revs);
753         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
754
755         refs = revs.pending;
756         revs.leak_pending = 1;
757
758         if (prepare_revision_walk(&revs))
759                 die(_("internal error in revision walk"));
760         if (!(old->object.flags & UNINTERESTING))
761                 suggest_reattach(old, &revs);
762         else
763                 describe_detached_head(_("Previous HEAD position was"), old);
764
765         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
766         free(refs.objects);
767 }
768
769 static int switch_branches(const struct checkout_opts *opts,
770                            struct branch_info *new)
771 {
772         int ret = 0;
773         struct branch_info old;
774         void *path_to_free;
775         unsigned char rev[20];
776         int flag, writeout_error = 0;
777         memset(&old, 0, sizeof(old));
778         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
779         old.commit = lookup_commit_reference_gently(rev, 1);
780         if (!(flag & REF_ISSYMREF))
781                 old.path = NULL;
782
783         if (old.path && !prefixcmp(old.path, "refs/heads/"))
784                 old.name = old.path + strlen("refs/heads/");
785
786         if (!new->name) {
787                 new->name = "HEAD";
788                 new->commit = old.commit;
789                 if (!new->commit)
790                         die(_("You are on a branch yet to be born"));
791                 parse_commit(new->commit);
792         }
793
794         ret = merge_working_tree(opts, &old, new, &writeout_error);
795         if (ret) {
796                 free(path_to_free);
797                 return ret;
798         }
799
800         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
801                 orphaned_commit_warning(old.commit, new->commit);
802
803         update_refs_for_switch(opts, &old, new);
804
805         ret = post_checkout_hook(old.commit, new->commit, 1);
806         free(path_to_free);
807         return ret || writeout_error;
808 }
809
810 static int git_checkout_config(const char *var, const char *value, void *cb)
811 {
812         if (!strcmp(var, "diff.ignoresubmodules")) {
813                 struct checkout_opts *opts = cb;
814                 handle_ignore_submodules_arg(&opts->diff_options, value);
815                 return 0;
816         }
817
818         if (!prefixcmp(var, "submodule."))
819                 return parse_submodule_config_option(var, value);
820
821         return git_xmerge_config(var, value, NULL);
822 }
823
824 struct tracking_name_data {
825         const char *name;
826         char *remote;
827         int unique;
828 };
829
830 static int check_tracking_name(const char *refname, const unsigned char *sha1,
831                                int flags, void *cb_data)
832 {
833         struct tracking_name_data *cb = cb_data;
834         const char *slash;
835
836         if (prefixcmp(refname, "refs/remotes/"))
837                 return 0;
838         slash = strchr(refname + 13, '/');
839         if (!slash || strcmp(slash + 1, cb->name))
840                 return 0;
841         if (cb->remote) {
842                 cb->unique = 0;
843                 return 0;
844         }
845         cb->remote = xstrdup(refname);
846         return 0;
847 }
848
849 static const char *unique_tracking_name(const char *name)
850 {
851         struct tracking_name_data cb_data = { NULL, NULL, 1 };
852         cb_data.name = name;
853         for_each_ref(check_tracking_name, &cb_data);
854         if (cb_data.unique)
855                 return cb_data.remote;
856         free(cb_data.remote);
857         return NULL;
858 }
859
860 static int parse_branchname_arg(int argc, const char **argv,
861                                 int dwim_new_local_branch_ok,
862                                 struct branch_info *new,
863                                 struct tree **source_tree,
864                                 unsigned char rev[20],
865                                 const char **new_branch)
866 {
867         int argcount = 0;
868         unsigned char branch_rev[20];
869         const char *arg;
870         int has_dash_dash;
871
872         /*
873          * case 1: git checkout <ref> -- [<paths>]
874          *
875          *   <ref> must be a valid tree, everything after the '--' must be
876          *   a path.
877          *
878          * case 2: git checkout -- [<paths>]
879          *
880          *   everything after the '--' must be paths.
881          *
882          * case 3: git checkout <something> [<paths>]
883          *
884          *   With no paths, if <something> is a commit, that is to
885          *   switch to the branch or detach HEAD at it.  As a special case,
886          *   if <something> is A...B (missing A or B means HEAD but you can
887          *   omit at most one side), and if there is a unique merge base
888          *   between A and B, A...B names that merge base.
889          *
890          *   With no paths, if <something> is _not_ a commit, no -t nor -b
891          *   was given, and there is a tracking branch whose name is
892          *   <something> in one and only one remote, then this is a short-hand
893          *   to fork local <something> from that remote-tracking branch.
894          *
895          *   Otherwise <something> shall not be ambiguous.
896          *   - If it's *only* a reference, treat it like case (1).
897          *   - If it's only a path, treat it like case (2).
898          *   - else: fail.
899          *
900          */
901         if (!argc)
902                 return 0;
903
904         if (!strcmp(argv[0], "--"))     /* case (2) */
905                 return 1;
906
907         arg = argv[0];
908         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
909
910         if (!strcmp(arg, "-"))
911                 arg = "@{-1}";
912
913         if (get_sha1_mb(arg, rev)) {
914                 if (has_dash_dash)          /* case (1) */
915                         die(_("invalid reference: %s"), arg);
916                 if (dwim_new_local_branch_ok &&
917                     !check_filename(NULL, arg) &&
918                     argc == 1) {
919                         const char *remote = unique_tracking_name(arg);
920                         if (!remote || get_sha1(remote, rev))
921                                 return argcount;
922                         *new_branch = arg;
923                         arg = remote;
924                         /* DWIMmed to create local branch */
925                 } else {
926                         return argcount;
927                 }
928         }
929
930         /* we can't end up being in (2) anymore, eat the argument */
931         argcount++;
932         argv++;
933         argc--;
934
935         new->name = arg;
936         setup_branch_path(new);
937
938         if (!check_refname_format(new->path, 0) &&
939             !read_ref(new->path, branch_rev))
940                 hashcpy(rev, branch_rev);
941         else
942                 new->path = NULL; /* not an existing branch */
943
944         new->commit = lookup_commit_reference_gently(rev, 1);
945         if (!new->commit) {
946                 /* not a commit */
947                 *source_tree = parse_tree_indirect(rev);
948         } else {
949                 parse_commit(new->commit);
950                 *source_tree = new->commit->tree;
951         }
952
953         if (!*source_tree)                   /* case (1): want a tree */
954                 die(_("reference is not a tree: %s"), arg);
955         if (!has_dash_dash) {/* case (3 -> 1) */
956                 /*
957                  * Do not complain the most common case
958                  *      git checkout branch
959                  * even if there happen to be a file called 'branch';
960                  * it would be extremely annoying.
961                  */
962                 if (argc)
963                         verify_non_filename(NULL, arg);
964         } else {
965                 argcount++;
966                 argv++;
967                 argc--;
968         }
969
970         return argcount;
971 }
972
973 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
974 {
975         int status;
976         struct strbuf branch_ref = STRBUF_INIT;
977
978         if (!opts->new_branch)
979                 die(_("You are on a branch yet to be born"));
980         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
981         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
982         strbuf_release(&branch_ref);
983         if (!opts->quiet)
984                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
985                         opts->new_branch);
986         return status;
987 }
988
989 static int checkout_branch(struct checkout_opts *opts,
990                            struct branch_info *new)
991 {
992         if (opts->pathspec)
993                 die(_("paths cannot be used with switching branches"));
994
995         if (opts->patch_mode)
996                 die(_("'%s' cannot be used with switching branches"),
997                     "--patch");
998
999         if (opts->writeout_stage)
1000                 die(_("'%s' cannot be used with switching branches"),
1001                     "--ours/--theirs");
1002
1003         if (opts->force && opts->merge)
1004                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1005
1006         if (opts->force_detach && opts->new_branch)
1007                 die(_("'%s' cannot be used with '%s'"),
1008                     "--detach", "-b/-B/--orphan");
1009
1010         if (opts->new_orphan_branch) {
1011                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1012                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1013         } else if (opts->force_detach) {
1014                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1015                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1016         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1017                 opts->track = git_branch_track;
1018
1019         if (new->name && !new->commit)
1020                 die(_("Cannot switch branch to a non-commit '%s'"),
1021                     new->name);
1022
1023         if (!new->commit && opts->new_branch) {
1024                 unsigned char rev[20];
1025                 int flag;
1026
1027                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
1028                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1029                         return switch_unborn_to_new_branch(opts);
1030         }
1031         return switch_branches(opts, new);
1032 }
1033
1034 int cmd_checkout(int argc, const char **argv, const char *prefix)
1035 {
1036         struct checkout_opts opts;
1037         struct branch_info new;
1038         char *conflict_style = NULL;
1039         int dwim_new_local_branch = 1;
1040         struct option options[] = {
1041                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1042                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1043                            N_("create and checkout a new branch")),
1044                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1045                            N_("create/reset and checkout a branch")),
1046                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1047                 OPT_BOOLEAN(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1048                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1049                         BRANCH_TRACK_EXPLICIT),
1050                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new branch"), N_("new unparented branch")),
1051                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1052                             2),
1053                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1054                             3),
1055                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1056                 OPT_BOOLEAN('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1057                 OPT_BOOLEAN(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1058                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1059                            N_("conflict style (merge or diff3)")),
1060                 OPT_BOOLEAN('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1061                 { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
1062                   N_("second guess 'git checkout no-such-branch'"),
1063                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
1064                 OPT_END(),
1065         };
1066
1067         memset(&opts, 0, sizeof(opts));
1068         memset(&new, 0, sizeof(new));
1069         opts.overwrite_ignore = 1;
1070         opts.prefix = prefix;
1071
1072         gitmodules_config();
1073         git_config(git_checkout_config, &opts);
1074
1075         opts.track = BRANCH_TRACK_UNSPECIFIED;
1076
1077         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1078                              PARSE_OPT_KEEP_DASHDASH);
1079
1080         if (conflict_style) {
1081                 opts.merge = 1; /* implied */
1082                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1083         }
1084
1085         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1086                 die(_("-b, -B and --orphan are mutually exclusive"));
1087
1088         /*
1089          * From here on, new_branch will contain the branch to be checked out,
1090          * and new_branch_force and new_orphan_branch will tell us which one of
1091          * -b/-B/--orphan is being used.
1092          */
1093         if (opts.new_branch_force)
1094                 opts.new_branch = opts.new_branch_force;
1095
1096         if (opts.new_orphan_branch)
1097                 opts.new_branch = opts.new_orphan_branch;
1098
1099         /* --track without -b/-B/--orphan should DWIM */
1100         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1101                 const char *argv0 = argv[0];
1102                 if (!argc || !strcmp(argv0, "--"))
1103                         die (_("--track needs a branch name"));
1104                 if (!prefixcmp(argv0, "refs/"))
1105                         argv0 += 5;
1106                 if (!prefixcmp(argv0, "remotes/"))
1107                         argv0 += 8;
1108                 argv0 = strchr(argv0, '/');
1109                 if (!argv0 || !argv0[1])
1110                         die (_("Missing branch name; try -b"));
1111                 opts.new_branch = argv0 + 1;
1112         }
1113
1114         /*
1115          * Extract branch name from command line arguments, so
1116          * all that is left is pathspecs.
1117          *
1118          * Handle
1119          *
1120          *  1) git checkout <tree> -- [<paths>]
1121          *  2) git checkout -- [<paths>]
1122          *  3) git checkout <something> [<paths>]
1123          *
1124          * including "last branch" syntax and DWIM-ery for names of
1125          * remote branches, erroring out for invalid or ambiguous cases.
1126          */
1127         if (argc) {
1128                 unsigned char rev[20];
1129                 int dwim_ok =
1130                         !opts.patch_mode &&
1131                         dwim_new_local_branch &&
1132                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1133                         !opts.new_branch;
1134                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1135                                              &new, &opts.source_tree,
1136                                              rev, &opts.new_branch);
1137                 argv += n;
1138                 argc -= n;
1139         }
1140
1141         if (argc) {
1142                 opts.pathspec = get_pathspec(prefix, argv);
1143
1144                 if (!opts.pathspec)
1145                         die(_("invalid path specification"));
1146
1147                 /*
1148                  * Try to give more helpful suggestion.
1149                  * new_branch && argc > 1 will be caught later.
1150                  */
1151                 if (opts.new_branch && argc == 1)
1152                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1153                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1154                             opts.new_branch, argv[0]);
1155
1156                 if (opts.force_detach)
1157                         die(_("git checkout: --detach does not take a path argument '%s'"),
1158                             argv[0]);
1159
1160                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1161                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1162                               "checking out of the index."));
1163         }
1164
1165         if (opts.new_branch) {
1166                 struct strbuf buf = STRBUF_INIT;
1167
1168                 opts.branch_exists =
1169                         validate_new_branchname(opts.new_branch, &buf,
1170                                                 !!opts.new_branch_force,
1171                                                 !!opts.new_branch_force);
1172
1173                 strbuf_release(&buf);
1174         }
1175
1176         if (opts.patch_mode || opts.pathspec)
1177                 return checkout_paths(&opts, new.name);
1178         else
1179                 return checkout_branch(&opts, &new);
1180 }