Merge branch 'jc/revision-range-unpeel'
[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         int ignore_skipworktree;
39
40         const char *new_branch;
41         const char *new_branch_force;
42         const char *new_orphan_branch;
43         int new_branch_log;
44         enum branch_track track;
45         struct diff_options diff_options;
46
47         int branch_exists;
48         const char *prefix;
49         struct pathspec pathspec;
50         struct tree *source_tree;
51 };
52
53 static int post_checkout_hook(struct commit *old, struct commit *new,
54                               int changed)
55 {
56         return run_hook(NULL, "post-checkout",
57                         sha1_to_hex(old ? old->object.sha1 : null_sha1),
58                         sha1_to_hex(new ? new->object.sha1 : null_sha1),
59                         changed ? "1" : "0", NULL);
60         /* "new" can be NULL when checking out from the index before
61            a commit exists. */
62
63 }
64
65 static int update_some(const unsigned char *sha1, const char *base, int baselen,
66                 const char *pathname, unsigned mode, int stage, void *context)
67 {
68         int len;
69         struct cache_entry *ce;
70
71         if (S_ISDIR(mode))
72                 return READ_TREE_RECURSIVE;
73
74         len = baselen + strlen(pathname);
75         ce = xcalloc(1, cache_entry_size(len));
76         hashcpy(ce->sha1, sha1);
77         memcpy(ce->name, base, baselen);
78         memcpy(ce->name + baselen, pathname, len - baselen);
79         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
80         ce->ce_namelen = len;
81         ce->ce_mode = create_ce_mode(mode);
82         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
83         return 0;
84 }
85
86 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
87 {
88         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
89
90         /* update the index with the given tree's info
91          * for all args, expanding wildcards, and exit
92          * with any non-zero return code.
93          */
94         return 0;
95 }
96
97 static int skip_same_name(const struct cache_entry *ce, int pos)
98 {
99         while (++pos < active_nr &&
100                !strcmp(active_cache[pos]->name, ce->name))
101                 ; /* skip */
102         return pos;
103 }
104
105 static int check_stage(int stage, const struct cache_entry *ce, int pos)
106 {
107         while (pos < active_nr &&
108                !strcmp(active_cache[pos]->name, ce->name)) {
109                 if (ce_stage(active_cache[pos]) == stage)
110                         return 0;
111                 pos++;
112         }
113         if (stage == 2)
114                 return error(_("path '%s' does not have our version"), ce->name);
115         else
116                 return error(_("path '%s' does not have their version"), ce->name);
117 }
118
119 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
120 {
121         unsigned seen = 0;
122         const char *name = ce->name;
123
124         while (pos < active_nr) {
125                 ce = active_cache[pos];
126                 if (strcmp(name, ce->name))
127                         break;
128                 seen |= (1 << ce_stage(ce));
129                 pos++;
130         }
131         if ((stages & seen) != stages)
132                 return error(_("path '%s' does not have all necessary versions"),
133                              name);
134         return 0;
135 }
136
137 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
138                           struct checkout *state)
139 {
140         while (pos < active_nr &&
141                !strcmp(active_cache[pos]->name, ce->name)) {
142                 if (ce_stage(active_cache[pos]) == stage)
143                         return checkout_entry(active_cache[pos], state, NULL);
144                 pos++;
145         }
146         if (stage == 2)
147                 return error(_("path '%s' does not have our version"), ce->name);
148         else
149                 return error(_("path '%s' does not have their version"), ce->name);
150 }
151
152 static int checkout_merged(int pos, struct checkout *state)
153 {
154         struct cache_entry *ce = active_cache[pos];
155         const char *path = ce->name;
156         mmfile_t ancestor, ours, theirs;
157         int status;
158         unsigned char sha1[20];
159         mmbuffer_t result_buf;
160         unsigned char threeway[3][20];
161         unsigned mode = 0;
162
163         memset(threeway, 0, sizeof(threeway));
164         while (pos < active_nr) {
165                 int stage;
166                 stage = ce_stage(ce);
167                 if (!stage || strcmp(path, ce->name))
168                         break;
169                 hashcpy(threeway[stage - 1], ce->sha1);
170                 if (stage == 2)
171                         mode = create_ce_mode(ce->ce_mode);
172                 pos++;
173                 ce = active_cache[pos];
174         }
175         if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
176                 return error(_("path '%s' does not have necessary versions"), path);
177
178         read_mmblob(&ancestor, threeway[0]);
179         read_mmblob(&ours, threeway[1]);
180         read_mmblob(&theirs, threeway[2]);
181
182         /*
183          * NEEDSWORK: re-create conflicts from merges with
184          * merge.renormalize set, too
185          */
186         status = ll_merge(&result_buf, path, &ancestor, "base",
187                           &ours, "ours", &theirs, "theirs", NULL);
188         free(ancestor.ptr);
189         free(ours.ptr);
190         free(theirs.ptr);
191         if (status < 0 || !result_buf.ptr) {
192                 free(result_buf.ptr);
193                 return error(_("path '%s': cannot merge"), path);
194         }
195
196         /*
197          * NEEDSWORK:
198          * There is absolutely no reason to write this as a blob object
199          * and create a phony cache entry just to leak.  This hack is
200          * primarily to get to the write_entry() machinery that massages
201          * the contents to work-tree format and writes out which only
202          * allows it for a cache entry.  The code in write_entry() needs
203          * to be refactored to allow us to feed a <buffer, size, mode>
204          * instead of a cache entry.  Such a refactoring would help
205          * merge_recursive as well (it also writes the merge result to the
206          * object database even when it may contain conflicts).
207          */
208         if (write_sha1_file(result_buf.ptr, result_buf.size,
209                             blob_type, sha1))
210                 die(_("Unable to add merge result for '%s'"), path);
211         ce = make_cache_entry(mode, sha1, path, 2, 0);
212         if (!ce)
213                 die(_("make_cache_entry failed for path '%s'"), path);
214         status = checkout_entry(ce, state, NULL);
215         return status;
216 }
217
218 static int checkout_paths(const struct checkout_opts *opts,
219                           const char *revision)
220 {
221         int pos;
222         struct checkout state;
223         static char *ps_matched;
224         unsigned char rev[20];
225         int flag;
226         struct commit *head;
227         int errs = 0;
228         int newfd;
229         struct lock_file *lock_file;
230
231         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
232                 die(_("'%s' cannot be used with updating paths"), "--track");
233
234         if (opts->new_branch_log)
235                 die(_("'%s' cannot be used with updating paths"), "-l");
236
237         if (opts->force && opts->patch_mode)
238                 die(_("'%s' cannot be used with updating paths"), "-f");
239
240         if (opts->force_detach)
241                 die(_("'%s' cannot be used with updating paths"), "--detach");
242
243         if (opts->merge && opts->patch_mode)
244                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
245
246         if (opts->force && opts->merge)
247                 die(_("'%s' cannot be used with %s"), "-f", "-m");
248
249         if (opts->new_branch)
250                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
251                     opts->new_branch);
252
253         if (opts->patch_mode)
254                 return run_add_interactive(revision, "--patch=checkout",
255                                            &opts->pathspec);
256
257         lock_file = xcalloc(1, sizeof(struct lock_file));
258
259         newfd = hold_locked_index(lock_file, 1);
260         if (read_cache_preload(&opts->pathspec) < 0)
261                 return error(_("corrupt index file"));
262
263         if (opts->source_tree)
264                 read_tree_some(opts->source_tree, &opts->pathspec);
265
266         ps_matched = xcalloc(1, opts->pathspec.nr);
267
268         /*
269          * Make sure all pathspecs participated in locating the paths
270          * to be checked out.
271          */
272         for (pos = 0; pos < active_nr; pos++) {
273                 struct cache_entry *ce = active_cache[pos];
274                 ce->ce_flags &= ~CE_MATCHED;
275                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
276                         continue;
277                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
278                         /*
279                          * "git checkout tree-ish -- path", but this entry
280                          * is in the original index; it will not be checked
281                          * out to the working tree and it does not matter
282                          * if pathspec matched this entry.  We will not do
283                          * anything to this entry at all.
284                          */
285                         continue;
286                 /*
287                  * Either this entry came from the tree-ish we are
288                  * checking the paths out of, or we are checking out
289                  * of the index.
290                  *
291                  * If it comes from the tree-ish, we already know it
292                  * matches the pathspec and could just stamp
293                  * CE_MATCHED to it from update_some(). But we still
294                  * need ps_matched and read_tree_recursive (and
295                  * eventually tree_entry_interesting) cannot fill
296                  * ps_matched yet. Once it can, we can avoid calling
297                  * match_pathspec() for _all_ entries when
298                  * opts->source_tree != NULL.
299                  */
300                 if (match_pathspec_depth(&opts->pathspec, ce->name, ce_namelen(ce),
301                                    0, ps_matched))
302                         ce->ce_flags |= CE_MATCHED;
303         }
304
305         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
306                 free(ps_matched);
307                 return 1;
308         }
309         free(ps_matched);
310
311         /* "checkout -m path" to recreate conflicted state */
312         if (opts->merge)
313                 unmerge_marked_index(&the_index);
314
315         /* Any unmerged paths? */
316         for (pos = 0; pos < active_nr; pos++) {
317                 const struct cache_entry *ce = active_cache[pos];
318                 if (ce->ce_flags & CE_MATCHED) {
319                         if (!ce_stage(ce))
320                                 continue;
321                         if (opts->force) {
322                                 warning(_("path '%s' is unmerged"), ce->name);
323                         } else if (opts->writeout_stage) {
324                                 errs |= check_stage(opts->writeout_stage, ce, pos);
325                         } else if (opts->merge) {
326                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
327                         } else {
328                                 errs = 1;
329                                 error(_("path '%s' is unmerged"), ce->name);
330                         }
331                         pos = skip_same_name(ce, pos) - 1;
332                 }
333         }
334         if (errs)
335                 return 1;
336
337         /* Now we are committed to check them out */
338         memset(&state, 0, sizeof(state));
339         state.force = 1;
340         state.refresh_cache = 1;
341         for (pos = 0; pos < active_nr; pos++) {
342                 struct cache_entry *ce = active_cache[pos];
343                 if (ce->ce_flags & CE_MATCHED) {
344                         if (!ce_stage(ce)) {
345                                 errs |= checkout_entry(ce, &state, NULL);
346                                 continue;
347                         }
348                         if (opts->writeout_stage)
349                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
350                         else if (opts->merge)
351                                 errs |= checkout_merged(pos, &state);
352                         pos = skip_same_name(ce, pos) - 1;
353                 }
354         }
355
356         if (write_cache(newfd, active_cache, active_nr) ||
357             commit_locked_index(lock_file))
358                 die(_("unable to write new index file"));
359
360         read_ref_full("HEAD", rev, 0, &flag);
361         head = lookup_commit_reference_gently(rev, 1);
362
363         errs |= post_checkout_hook(head, head, 0);
364         return errs;
365 }
366
367 static void show_local_changes(struct object *head,
368                                const struct diff_options *opts)
369 {
370         struct rev_info rev;
371         /* I think we want full paths, even if we're in a subdirectory. */
372         init_revisions(&rev, NULL);
373         rev.diffopt.flags = opts->flags;
374         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
375         diff_setup_done(&rev.diffopt);
376         add_pending_object(&rev, head, NULL);
377         run_diff_index(&rev, 0);
378 }
379
380 static void describe_detached_head(const char *msg, struct commit *commit)
381 {
382         struct strbuf sb = STRBUF_INIT;
383         parse_commit(commit);
384         pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
385         fprintf(stderr, "%s %s... %s\n", msg,
386                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
387         strbuf_release(&sb);
388 }
389
390 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
391                       int worktree, int *writeout_error)
392 {
393         struct unpack_trees_options opts;
394         struct tree_desc tree_desc;
395
396         memset(&opts, 0, sizeof(opts));
397         opts.head_idx = -1;
398         opts.update = worktree;
399         opts.skip_unmerged = !worktree;
400         opts.reset = 1;
401         opts.merge = 1;
402         opts.fn = oneway_merge;
403         opts.verbose_update = !o->quiet && isatty(2);
404         opts.src_index = &the_index;
405         opts.dst_index = &the_index;
406         parse_tree(tree);
407         init_tree_desc(&tree_desc, tree->buffer, tree->size);
408         switch (unpack_trees(1, &tree_desc, &opts)) {
409         case -2:
410                 *writeout_error = 1;
411                 /*
412                  * We return 0 nevertheless, as the index is all right
413                  * and more importantly we have made best efforts to
414                  * update paths in the work tree, and we cannot revert
415                  * them.
416                  */
417         case 0:
418                 return 0;
419         default:
420                 return 128;
421         }
422 }
423
424 struct branch_info {
425         const char *name; /* The short name used */
426         const char *path; /* The full name of a real branch */
427         struct commit *commit; /* The named commit */
428 };
429
430 static void setup_branch_path(struct branch_info *branch)
431 {
432         struct strbuf buf = STRBUF_INIT;
433
434         strbuf_branchname(&buf, branch->name);
435         if (strcmp(buf.buf, branch->name))
436                 branch->name = xstrdup(buf.buf);
437         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
438         branch->path = strbuf_detach(&buf, NULL);
439 }
440
441 static int merge_working_tree(const struct checkout_opts *opts,
442                               struct branch_info *old,
443                               struct branch_info *new,
444                               int *writeout_error)
445 {
446         int ret;
447         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
448         int newfd = hold_locked_index(lock_file, 1);
449
450         if (read_cache_preload(NULL) < 0)
451                 return error(_("corrupt index file"));
452
453         resolve_undo_clear();
454         if (opts->force) {
455                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
456                 if (ret)
457                         return ret;
458         } else {
459                 struct tree_desc trees[2];
460                 struct tree *tree;
461                 struct unpack_trees_options topts;
462
463                 memset(&topts, 0, sizeof(topts));
464                 topts.head_idx = -1;
465                 topts.src_index = &the_index;
466                 topts.dst_index = &the_index;
467
468                 setup_unpack_trees_porcelain(&topts, "checkout");
469
470                 refresh_cache(REFRESH_QUIET);
471
472                 if (unmerged_cache()) {
473                         error(_("you need to resolve your current index first"));
474                         return 1;
475                 }
476
477                 /* 2-way merge to the new branch */
478                 topts.initial_checkout = is_cache_unborn();
479                 topts.update = 1;
480                 topts.merge = 1;
481                 topts.gently = opts->merge && old->commit;
482                 topts.verbose_update = !opts->quiet && isatty(2);
483                 topts.fn = twoway_merge;
484                 if (opts->overwrite_ignore) {
485                         topts.dir = xcalloc(1, sizeof(*topts.dir));
486                         topts.dir->flags |= DIR_SHOW_IGNORED;
487                         setup_standard_excludes(topts.dir);
488                 }
489                 tree = parse_tree_indirect(old->commit ?
490                                            old->commit->object.sha1 :
491                                            EMPTY_TREE_SHA1_BIN);
492                 init_tree_desc(&trees[0], tree->buffer, tree->size);
493                 tree = parse_tree_indirect(new->commit->object.sha1);
494                 init_tree_desc(&trees[1], tree->buffer, tree->size);
495
496                 ret = unpack_trees(2, trees, &topts);
497                 if (ret == -1) {
498                         /*
499                          * Unpack couldn't do a trivial merge; either
500                          * give up or do a real merge, depending on
501                          * whether the merge flag was used.
502                          */
503                         struct tree *result;
504                         struct tree *work;
505                         struct merge_options o;
506                         if (!opts->merge)
507                                 return 1;
508
509                         /*
510                          * Without old->commit, the below is the same as
511                          * the two-tree unpack we already tried and failed.
512                          */
513                         if (!old->commit)
514                                 return 1;
515
516                         /* Do more real merge */
517
518                         /*
519                          * We update the index fully, then write the
520                          * tree from the index, then merge the new
521                          * branch with the current tree, with the old
522                          * branch as the base. Then we reset the index
523                          * (but not the working tree) to the new
524                          * branch, leaving the working tree as the
525                          * merged version, but skipping unmerged
526                          * entries in the index.
527                          */
528
529                         add_files_to_cache(NULL, NULL, 0);
530                         /*
531                          * NEEDSWORK: carrying over local changes
532                          * when branches have different end-of-line
533                          * normalization (or clean+smudge rules) is
534                          * a pain; plumb in an option to set
535                          * o.renormalize?
536                          */
537                         init_merge_options(&o);
538                         o.verbosity = 0;
539                         work = write_tree_from_memory(&o);
540
541                         ret = reset_tree(new->commit->tree, opts, 1,
542                                          writeout_error);
543                         if (ret)
544                                 return ret;
545                         o.ancestor = old->name;
546                         o.branch1 = new->name;
547                         o.branch2 = "local";
548                         merge_trees(&o, new->commit->tree, work,
549                                 old->commit->tree, &result);
550                         ret = reset_tree(new->commit->tree, opts, 0,
551                                          writeout_error);
552                         if (ret)
553                                 return ret;
554                 }
555         }
556
557         if (write_cache(newfd, active_cache, active_nr) ||
558             commit_locked_index(lock_file))
559                 die(_("unable to write new index file"));
560
561         if (!opts->force && !opts->quiet)
562                 show_local_changes(&new->commit->object, &opts->diff_options);
563
564         return 0;
565 }
566
567 static void report_tracking(struct branch_info *new)
568 {
569         struct strbuf sb = STRBUF_INIT;
570         struct branch *branch = branch_get(new->name);
571
572         if (!format_tracking_info(branch, &sb))
573                 return;
574         fputs(sb.buf, stdout);
575         strbuf_release(&sb);
576 }
577
578 static void update_refs_for_switch(const struct checkout_opts *opts,
579                                    struct branch_info *old,
580                                    struct branch_info *new)
581 {
582         struct strbuf msg = STRBUF_INIT;
583         const char *old_desc, *reflog_msg;
584         if (opts->new_branch) {
585                 if (opts->new_orphan_branch) {
586                         if (opts->new_branch_log && !log_all_ref_updates) {
587                                 int temp;
588                                 char log_file[PATH_MAX];
589                                 char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
590
591                                 temp = log_all_ref_updates;
592                                 log_all_ref_updates = 1;
593                                 if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
594                                         fprintf(stderr, _("Can not do reflog for '%s'\n"),
595                                             opts->new_orphan_branch);
596                                         log_all_ref_updates = temp;
597                                         return;
598                                 }
599                                 log_all_ref_updates = temp;
600                         }
601                 }
602                 else
603                         create_branch(old->name, opts->new_branch, new->name,
604                                       opts->new_branch_force ? 1 : 0,
605                                       opts->new_branch_log,
606                                       opts->new_branch_force ? 1 : 0,
607                                       opts->quiet,
608                                       opts->track);
609                 new->name = opts->new_branch;
610                 setup_branch_path(new);
611         }
612
613         old_desc = old->name;
614         if (!old_desc && old->commit)
615                 old_desc = sha1_to_hex(old->commit->object.sha1);
616
617         reflog_msg = getenv("GIT_REFLOG_ACTION");
618         if (!reflog_msg)
619                 strbuf_addf(&msg, "checkout: moving from %s to %s",
620                         old_desc ? old_desc : "(invalid)", new->name);
621         else
622                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
623
624         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
625                 /* Nothing to do. */
626         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
627                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
628                            REF_NODEREF, DIE_ON_ERR);
629                 if (!opts->quiet) {
630                         if (old->path && advice_detached_head)
631                                 detach_advice(new->name);
632                         describe_detached_head(_("HEAD is now at"), new->commit);
633                 }
634         } else if (new->path) { /* Switch branches. */
635                 create_symref("HEAD", new->path, msg.buf);
636                 if (!opts->quiet) {
637                         if (old->path && !strcmp(new->path, old->path)) {
638                                 if (opts->new_branch_force)
639                                         fprintf(stderr, _("Reset branch '%s'\n"),
640                                                 new->name);
641                                 else
642                                         fprintf(stderr, _("Already on '%s'\n"),
643                                                 new->name);
644                         } else if (opts->new_branch) {
645                                 if (opts->branch_exists)
646                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
647                                 else
648                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
649                         } else {
650                                 fprintf(stderr, _("Switched to branch '%s'\n"),
651                                         new->name);
652                         }
653                 }
654                 if (old->path && old->name) {
655                         char log_file[PATH_MAX], ref_file[PATH_MAX];
656
657                         git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
658                         git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
659                         if (!file_exists(ref_file) && file_exists(log_file))
660                                 remove_path(log_file);
661                 }
662         }
663         remove_branch_state();
664         strbuf_release(&msg);
665         if (!opts->quiet &&
666             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
667                 report_tracking(new);
668 }
669
670 static int add_pending_uninteresting_ref(const char *refname,
671                                          const unsigned char *sha1,
672                                          int flags, void *cb_data)
673 {
674         add_pending_sha1(cb_data, refname, sha1, UNINTERESTING);
675         return 0;
676 }
677
678 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
679 {
680         parse_commit(commit);
681         strbuf_addstr(sb, "  ");
682         strbuf_addstr(sb,
683                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
684         strbuf_addch(sb, ' ');
685         pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
686         strbuf_addch(sb, '\n');
687 }
688
689 #define ORPHAN_CUTOFF 4
690 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
691 {
692         struct commit *c, *last = NULL;
693         struct strbuf sb = STRBUF_INIT;
694         int lost = 0;
695         while ((c = get_revision(revs)) != NULL) {
696                 if (lost < ORPHAN_CUTOFF)
697                         describe_one_orphan(&sb, c);
698                 last = c;
699                 lost++;
700         }
701         if (ORPHAN_CUTOFF < lost) {
702                 int more = lost - ORPHAN_CUTOFF;
703                 if (more == 1)
704                         describe_one_orphan(&sb, last);
705                 else
706                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
707         }
708
709         fprintf(stderr,
710                 Q_(
711                 /* The singular version */
712                 "Warning: you are leaving %d commit behind, "
713                 "not connected to\n"
714                 "any of your branches:\n\n"
715                 "%s\n",
716                 /* The plural version */
717                 "Warning: you are leaving %d commits behind, "
718                 "not connected to\n"
719                 "any of your branches:\n\n"
720                 "%s\n",
721                 /* Give ngettext() the count */
722                 lost),
723                 lost,
724                 sb.buf);
725         strbuf_release(&sb);
726
727         if (advice_detached_head)
728                 fprintf(stderr,
729                         _(
730                         "If you want to keep them by creating a new branch, "
731                         "this may be a good time\nto do so with:\n\n"
732                         " git branch new_branch_name %s\n\n"),
733                         find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
734 }
735
736 /*
737  * We are about to leave commit that was at the tip of a detached
738  * HEAD.  If it is not reachable from any ref, this is the last chance
739  * for the user to do so without resorting to reflog.
740  */
741 static void orphaned_commit_warning(struct commit *old, struct commit *new)
742 {
743         struct rev_info revs;
744         struct object *object = &old->object;
745         struct object_array refs;
746
747         init_revisions(&revs, NULL);
748         setup_revisions(0, NULL, &revs, NULL);
749
750         object->flags &= ~UNINTERESTING;
751         add_pending_object(&revs, object, sha1_to_hex(object->sha1));
752
753         for_each_ref(add_pending_uninteresting_ref, &revs);
754         add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
755
756         refs = revs.pending;
757         revs.leak_pending = 1;
758
759         if (prepare_revision_walk(&revs))
760                 die(_("internal error in revision walk"));
761         if (!(old->object.flags & UNINTERESTING))
762                 suggest_reattach(old, &revs);
763         else
764                 describe_detached_head(_("Previous HEAD position was"), old);
765
766         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
767         free(refs.objects);
768 }
769
770 static int switch_branches(const struct checkout_opts *opts,
771                            struct branch_info *new)
772 {
773         int ret = 0;
774         struct branch_info old;
775         void *path_to_free;
776         unsigned char rev[20];
777         int flag, writeout_error = 0;
778         memset(&old, 0, sizeof(old));
779         old.path = path_to_free = resolve_refdup("HEAD", rev, 0, &flag);
780         old.commit = lookup_commit_reference_gently(rev, 1);
781         if (!(flag & REF_ISSYMREF))
782                 old.path = NULL;
783
784         if (old.path && !prefixcmp(old.path, "refs/heads/"))
785                 old.name = old.path + strlen("refs/heads/");
786
787         if (!new->name) {
788                 new->name = "HEAD";
789                 new->commit = old.commit;
790                 if (!new->commit)
791                         die(_("You are on a branch yet to be born"));
792                 parse_commit(new->commit);
793         }
794
795         ret = merge_working_tree(opts, &old, new, &writeout_error);
796         if (ret) {
797                 free(path_to_free);
798                 return ret;
799         }
800
801         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
802                 orphaned_commit_warning(old.commit, new->commit);
803
804         update_refs_for_switch(opts, &old, new);
805
806         ret = post_checkout_hook(old.commit, new->commit, 1);
807         free(path_to_free);
808         return ret || writeout_error;
809 }
810
811 static int git_checkout_config(const char *var, const char *value, void *cb)
812 {
813         if (!strcmp(var, "diff.ignoresubmodules")) {
814                 struct checkout_opts *opts = cb;
815                 handle_ignore_submodules_arg(&opts->diff_options, value);
816                 return 0;
817         }
818
819         if (!prefixcmp(var, "submodule."))
820                 return parse_submodule_config_option(var, value);
821
822         return git_xmerge_config(var, value, NULL);
823 }
824
825 struct tracking_name_data {
826         /* const */ char *src_ref;
827         char *dst_ref;
828         unsigned char *dst_sha1;
829         int unique;
830 };
831
832 static int check_tracking_name(struct remote *remote, void *cb_data)
833 {
834         struct tracking_name_data *cb = cb_data;
835         struct refspec query;
836         memset(&query, 0, sizeof(struct refspec));
837         query.src = cb->src_ref;
838         if (remote_find_tracking(remote, &query) ||
839             get_sha1(query.dst, cb->dst_sha1)) {
840                 free(query.dst);
841                 return 0;
842         }
843         if (cb->dst_ref) {
844                 free(query.dst);
845                 cb->unique = 0;
846                 return 0;
847         }
848         cb->dst_ref = query.dst;
849         return 0;
850 }
851
852 static const char *unique_tracking_name(const char *name, unsigned char *sha1)
853 {
854         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
855         char src_ref[PATH_MAX];
856         snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
857         cb_data.src_ref = src_ref;
858         cb_data.dst_sha1 = sha1;
859         for_each_remote(check_tracking_name, &cb_data);
860         if (cb_data.unique)
861                 return cb_data.dst_ref;
862         free(cb_data.dst_ref);
863         return NULL;
864 }
865
866 static int parse_branchname_arg(int argc, const char **argv,
867                                 int dwim_new_local_branch_ok,
868                                 struct branch_info *new,
869                                 struct tree **source_tree,
870                                 unsigned char rev[20],
871                                 const char **new_branch)
872 {
873         int argcount = 0;
874         unsigned char branch_rev[20];
875         const char *arg;
876         int has_dash_dash;
877
878         /*
879          * case 1: git checkout <ref> -- [<paths>]
880          *
881          *   <ref> must be a valid tree, everything after the '--' must be
882          *   a path.
883          *
884          * case 2: git checkout -- [<paths>]
885          *
886          *   everything after the '--' must be paths.
887          *
888          * case 3: git checkout <something> [<paths>]
889          *
890          *   With no paths, if <something> is a commit, that is to
891          *   switch to the branch or detach HEAD at it.  As a special case,
892          *   if <something> is A...B (missing A or B means HEAD but you can
893          *   omit at most one side), and if there is a unique merge base
894          *   between A and B, A...B names that merge base.
895          *
896          *   With no paths, if <something> is _not_ a commit, no -t nor -b
897          *   was given, and there is a tracking branch whose name is
898          *   <something> in one and only one remote, then this is a short-hand
899          *   to fork local <something> from that remote-tracking branch.
900          *
901          *   Otherwise <something> shall not be ambiguous.
902          *   - If it's *only* a reference, treat it like case (1).
903          *   - If it's only a path, treat it like case (2).
904          *   - else: fail.
905          *
906          */
907         if (!argc)
908                 return 0;
909
910         if (!strcmp(argv[0], "--"))     /* case (2) */
911                 return 1;
912
913         arg = argv[0];
914         has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
915
916         if (!strcmp(arg, "-"))
917                 arg = "@{-1}";
918
919         if (get_sha1_mb(arg, rev)) {
920                 if (has_dash_dash)          /* case (1) */
921                         die(_("invalid reference: %s"), arg);
922                 if (dwim_new_local_branch_ok &&
923                     !check_filename(NULL, arg) &&
924                     argc == 1) {
925                         const char *remote = unique_tracking_name(arg, rev);
926                         if (!remote)
927                                 return argcount;
928                         *new_branch = arg;
929                         arg = remote;
930                         /* DWIMmed to create local branch */
931                 } else {
932                         return argcount;
933                 }
934         }
935
936         /* we can't end up being in (2) anymore, eat the argument */
937         argcount++;
938         argv++;
939         argc--;
940
941         new->name = arg;
942         setup_branch_path(new);
943
944         if (!check_refname_format(new->path, 0) &&
945             !read_ref(new->path, branch_rev))
946                 hashcpy(rev, branch_rev);
947         else
948                 new->path = NULL; /* not an existing branch */
949
950         new->commit = lookup_commit_reference_gently(rev, 1);
951         if (!new->commit) {
952                 /* not a commit */
953                 *source_tree = parse_tree_indirect(rev);
954         } else {
955                 parse_commit(new->commit);
956                 *source_tree = new->commit->tree;
957         }
958
959         if (!*source_tree)                   /* case (1): want a tree */
960                 die(_("reference is not a tree: %s"), arg);
961         if (!has_dash_dash) {/* case (3 -> 1) */
962                 /*
963                  * Do not complain the most common case
964                  *      git checkout branch
965                  * even if there happen to be a file called 'branch';
966                  * it would be extremely annoying.
967                  */
968                 if (argc)
969                         verify_non_filename(NULL, arg);
970         } else {
971                 argcount++;
972                 argv++;
973                 argc--;
974         }
975
976         return argcount;
977 }
978
979 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
980 {
981         int status;
982         struct strbuf branch_ref = STRBUF_INIT;
983
984         if (!opts->new_branch)
985                 die(_("You are on a branch yet to be born"));
986         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
987         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
988         strbuf_release(&branch_ref);
989         if (!opts->quiet)
990                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
991                         opts->new_branch);
992         return status;
993 }
994
995 static int checkout_branch(struct checkout_opts *opts,
996                            struct branch_info *new)
997 {
998         if (opts->pathspec.nr)
999                 die(_("paths cannot be used with switching branches"));
1000
1001         if (opts->patch_mode)
1002                 die(_("'%s' cannot be used with switching branches"),
1003                     "--patch");
1004
1005         if (opts->writeout_stage)
1006                 die(_("'%s' cannot be used with switching branches"),
1007                     "--ours/--theirs");
1008
1009         if (opts->force && opts->merge)
1010                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1011
1012         if (opts->force_detach && opts->new_branch)
1013                 die(_("'%s' cannot be used with '%s'"),
1014                     "--detach", "-b/-B/--orphan");
1015
1016         if (opts->new_orphan_branch) {
1017                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1018                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1019         } else if (opts->force_detach) {
1020                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1021                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1022         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1023                 opts->track = git_branch_track;
1024
1025         if (new->name && !new->commit)
1026                 die(_("Cannot switch branch to a non-commit '%s'"),
1027                     new->name);
1028
1029         if (!new->commit && opts->new_branch) {
1030                 unsigned char rev[20];
1031                 int flag;
1032
1033                 if (!read_ref_full("HEAD", rev, 0, &flag) &&
1034                     (flag & REF_ISSYMREF) && is_null_sha1(rev))
1035                         return switch_unborn_to_new_branch(opts);
1036         }
1037         return switch_branches(opts, new);
1038 }
1039
1040 int cmd_checkout(int argc, const char **argv, const char *prefix)
1041 {
1042         struct checkout_opts opts;
1043         struct branch_info new;
1044         char *conflict_style = NULL;
1045         int dwim_new_local_branch = 1;
1046         struct option options[] = {
1047                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1048                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1049                            N_("create and checkout a new branch")),
1050                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1051                            N_("create/reset and checkout a branch")),
1052                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1053                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1054                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1055                         BRANCH_TRACK_EXPLICIT),
1056                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new branch"), N_("new unparented branch")),
1057                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1058                             2),
1059                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1060                             3),
1061                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1062                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1063                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1064                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1065                            N_("conflict style (merge or diff3)")),
1066                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1067                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1068                          N_("do not limit pathspecs to sparse entries only")),
1069                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1070                                 N_("second guess 'git checkout no-such-branch'")),
1071                 OPT_END(),
1072         };
1073
1074         memset(&opts, 0, sizeof(opts));
1075         memset(&new, 0, sizeof(new));
1076         opts.overwrite_ignore = 1;
1077         opts.prefix = prefix;
1078
1079         gitmodules_config();
1080         git_config(git_checkout_config, &opts);
1081
1082         opts.track = BRANCH_TRACK_UNSPECIFIED;
1083
1084         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1085                              PARSE_OPT_KEEP_DASHDASH);
1086
1087         if (conflict_style) {
1088                 opts.merge = 1; /* implied */
1089                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1090         }
1091
1092         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1093                 die(_("-b, -B and --orphan are mutually exclusive"));
1094
1095         /*
1096          * From here on, new_branch will contain the branch to be checked out,
1097          * and new_branch_force and new_orphan_branch will tell us which one of
1098          * -b/-B/--orphan is being used.
1099          */
1100         if (opts.new_branch_force)
1101                 opts.new_branch = opts.new_branch_force;
1102
1103         if (opts.new_orphan_branch)
1104                 opts.new_branch = opts.new_orphan_branch;
1105
1106         /* --track without -b/-B/--orphan should DWIM */
1107         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1108                 const char *argv0 = argv[0];
1109                 if (!argc || !strcmp(argv0, "--"))
1110                         die (_("--track needs a branch name"));
1111                 if (!prefixcmp(argv0, "refs/"))
1112                         argv0 += 5;
1113                 if (!prefixcmp(argv0, "remotes/"))
1114                         argv0 += 8;
1115                 argv0 = strchr(argv0, '/');
1116                 if (!argv0 || !argv0[1])
1117                         die (_("Missing branch name; try -b"));
1118                 opts.new_branch = argv0 + 1;
1119         }
1120
1121         /*
1122          * Extract branch name from command line arguments, so
1123          * all that is left is pathspecs.
1124          *
1125          * Handle
1126          *
1127          *  1) git checkout <tree> -- [<paths>]
1128          *  2) git checkout -- [<paths>]
1129          *  3) git checkout <something> [<paths>]
1130          *
1131          * including "last branch" syntax and DWIM-ery for names of
1132          * remote branches, erroring out for invalid or ambiguous cases.
1133          */
1134         if (argc) {
1135                 unsigned char rev[20];
1136                 int dwim_ok =
1137                         !opts.patch_mode &&
1138                         dwim_new_local_branch &&
1139                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1140                         !opts.new_branch;
1141                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1142                                              &new, &opts.source_tree,
1143                                              rev, &opts.new_branch);
1144                 argv += n;
1145                 argc -= n;
1146         }
1147
1148         if (argc) {
1149                 parse_pathspec(&opts.pathspec, 0,
1150                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1151                                prefix, argv);
1152
1153                 if (!opts.pathspec.nr)
1154                         die(_("invalid path specification"));
1155
1156                 /*
1157                  * Try to give more helpful suggestion.
1158                  * new_branch && argc > 1 will be caught later.
1159                  */
1160                 if (opts.new_branch && argc == 1)
1161                         die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1162                               "Did you intend to checkout '%s' which can not be resolved as commit?"),
1163                             opts.new_branch, argv[0]);
1164
1165                 if (opts.force_detach)
1166                         die(_("git checkout: --detach does not take a path argument '%s'"),
1167                             argv[0]);
1168
1169                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1170                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1171                               "checking out of the index."));
1172         }
1173
1174         if (opts.new_branch) {
1175                 struct strbuf buf = STRBUF_INIT;
1176
1177                 opts.branch_exists =
1178                         validate_new_branchname(opts.new_branch, &buf,
1179                                                 !!opts.new_branch_force,
1180                                                 !!opts.new_branch_force);
1181
1182                 strbuf_release(&buf);
1183         }
1184
1185         if (opts.patch_mode || opts.pathspec.nr)
1186                 return checkout_paths(&opts, new.name);
1187         else
1188                 return checkout_branch(&opts, &new);
1189 }