bisect: only check merge bases when needed
[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 "unpack-trees.h"
9 #include "dir.h"
10 #include "run-command.h"
11 #include "merge-recursive.h"
12 #include "branch.h"
13 #include "diff.h"
14 #include "revision.h"
15 #include "remote.h"
16
17 static const char * const checkout_usage[] = {
18         "git checkout [options] <branch>",
19         "git checkout [options] [<branch>] -- <file>...",
20         NULL,
21 };
22
23 static int post_checkout_hook(struct commit *old, struct commit *new,
24                               int changed)
25 {
26         struct child_process proc;
27         const char *name = git_path("hooks/post-checkout");
28         const char *argv[5];
29
30         if (access(name, X_OK) < 0)
31                 return 0;
32
33         memset(&proc, 0, sizeof(proc));
34         argv[0] = name;
35         argv[1] = xstrdup(sha1_to_hex(old->object.sha1));
36         argv[2] = xstrdup(sha1_to_hex(new->object.sha1));
37         argv[3] = changed ? "1" : "0";
38         argv[4] = NULL;
39         proc.argv = argv;
40         proc.no_stdin = 1;
41         proc.stdout_to_stderr = 1;
42         return run_command(&proc);
43 }
44
45 static int update_some(const unsigned char *sha1, const char *base, int baselen,
46                 const char *pathname, unsigned mode, int stage, void *context)
47 {
48         int len;
49         struct cache_entry *ce;
50
51         if (S_ISGITLINK(mode))
52                 return 0;
53
54         if (S_ISDIR(mode))
55                 return READ_TREE_RECURSIVE;
56
57         len = baselen + strlen(pathname);
58         ce = xcalloc(1, cache_entry_size(len));
59         hashcpy(ce->sha1, sha1);
60         memcpy(ce->name, base, baselen);
61         memcpy(ce->name + baselen, pathname, len - baselen);
62         ce->ce_flags = create_ce_flags(len, 0);
63         ce->ce_mode = create_ce_mode(mode);
64         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
65         return 0;
66 }
67
68 static int read_tree_some(struct tree *tree, const char **pathspec)
69 {
70         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
71
72         /* update the index with the given tree's info
73          * for all args, expanding wildcards, and exit
74          * with any non-zero return code.
75          */
76         return 0;
77 }
78
79 static int checkout_paths(struct tree *source_tree, const char **pathspec)
80 {
81         int pos;
82         struct checkout state;
83         static char *ps_matched;
84         unsigned char rev[20];
85         int flag;
86         struct commit *head;
87         int errs = 0;
88
89         int newfd;
90         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
91
92         newfd = hold_locked_index(lock_file, 1);
93         read_cache();
94
95         if (source_tree)
96                 read_tree_some(source_tree, pathspec);
97
98         for (pos = 0; pathspec[pos]; pos++)
99                 ;
100         ps_matched = xcalloc(1, pos);
101
102         for (pos = 0; pos < active_nr; pos++) {
103                 struct cache_entry *ce = active_cache[pos];
104                 pathspec_match(pathspec, ps_matched, ce->name, 0);
105         }
106
107         if (report_path_error(ps_matched, pathspec, 0))
108                 return 1;
109
110         /* Now we are committed to check them out */
111         memset(&state, 0, sizeof(state));
112         state.force = 1;
113         state.refresh_cache = 1;
114         for (pos = 0; pos < active_nr; pos++) {
115                 struct cache_entry *ce = active_cache[pos];
116                 if (pathspec_match(pathspec, NULL, ce->name, 0)) {
117                         errs |= checkout_entry(ce, &state, NULL);
118                 }
119         }
120
121         if (write_cache(newfd, active_cache, active_nr) ||
122             commit_locked_index(lock_file))
123                 die("unable to write new index file");
124
125         resolve_ref("HEAD", rev, 0, &flag);
126         head = lookup_commit_reference_gently(rev, 1);
127
128         errs |= post_checkout_hook(head, head, 0);
129         return errs;
130 }
131
132 static void show_local_changes(struct object *head)
133 {
134         struct rev_info rev;
135         /* I think we want full paths, even if we're in a subdirectory. */
136         init_revisions(&rev, NULL);
137         rev.abbrev = 0;
138         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
139         add_pending_object(&rev, head, NULL);
140         run_diff_index(&rev, 0);
141 }
142
143 static void describe_detached_head(char *msg, struct commit *commit)
144 {
145         struct strbuf sb;
146         strbuf_init(&sb, 0);
147         parse_commit(commit);
148         pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
149         fprintf(stderr, "%s %s... %s\n", msg,
150                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
151         strbuf_release(&sb);
152 }
153
154 struct checkout_opts {
155         int quiet;
156         int merge;
157         int force;
158         int writeout_error;
159
160         const char *new_branch;
161         int new_branch_log;
162         enum branch_track track;
163 };
164
165 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
166 {
167         struct unpack_trees_options opts;
168         struct tree_desc tree_desc;
169
170         memset(&opts, 0, sizeof(opts));
171         opts.head_idx = -1;
172         opts.update = worktree;
173         opts.skip_unmerged = !worktree;
174         opts.reset = 1;
175         opts.merge = 1;
176         opts.fn = oneway_merge;
177         opts.verbose_update = !o->quiet;
178         opts.src_index = &the_index;
179         opts.dst_index = &the_index;
180         parse_tree(tree);
181         init_tree_desc(&tree_desc, tree->buffer, tree->size);
182         switch (unpack_trees(1, &tree_desc, &opts)) {
183         case -2:
184                 o->writeout_error = 1;
185                 /*
186                  * We return 0 nevertheless, as the index is all right
187                  * and more importantly we have made best efforts to
188                  * update paths in the work tree, and we cannot revert
189                  * them.
190                  */
191         case 0:
192                 return 0;
193         default:
194                 return 128;
195         }
196 }
197
198 struct branch_info {
199         const char *name; /* The short name used */
200         const char *path; /* The full name of a real branch */
201         struct commit *commit; /* The named commit */
202 };
203
204 static void setup_branch_path(struct branch_info *branch)
205 {
206         struct strbuf buf;
207         strbuf_init(&buf, 0);
208         strbuf_addstr(&buf, "refs/heads/");
209         strbuf_addstr(&buf, branch->name);
210         branch->path = strbuf_detach(&buf, NULL);
211 }
212
213 static int merge_working_tree(struct checkout_opts *opts,
214                               struct branch_info *old, struct branch_info *new)
215 {
216         int ret;
217         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
218         int newfd = hold_locked_index(lock_file, 1);
219         read_cache();
220
221         if (opts->force) {
222                 ret = reset_tree(new->commit->tree, opts, 1);
223                 if (ret)
224                         return ret;
225         } else {
226                 struct tree_desc trees[2];
227                 struct tree *tree;
228                 struct unpack_trees_options topts;
229
230                 memset(&topts, 0, sizeof(topts));
231                 topts.head_idx = -1;
232                 topts.src_index = &the_index;
233                 topts.dst_index = &the_index;
234
235                 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
236
237                 refresh_cache(REFRESH_QUIET);
238
239                 if (unmerged_cache()) {
240                         error("you need to resolve your current index first");
241                         return 1;
242                 }
243
244                 /* 2-way merge to the new branch */
245                 topts.update = 1;
246                 topts.merge = 1;
247                 topts.gently = opts->merge;
248                 topts.verbose_update = !opts->quiet;
249                 topts.fn = twoway_merge;
250                 topts.dir = xcalloc(1, sizeof(*topts.dir));
251                 topts.dir->show_ignored = 1;
252                 topts.dir->exclude_per_dir = ".gitignore";
253                 tree = parse_tree_indirect(old->commit->object.sha1);
254                 init_tree_desc(&trees[0], tree->buffer, tree->size);
255                 tree = parse_tree_indirect(new->commit->object.sha1);
256                 init_tree_desc(&trees[1], tree->buffer, tree->size);
257
258                 ret = unpack_trees(2, trees, &topts);
259                 if (ret == -1) {
260                         /*
261                          * Unpack couldn't do a trivial merge; either
262                          * give up or do a real merge, depending on
263                          * whether the merge flag was used.
264                          */
265                         struct tree *result;
266                         struct tree *work;
267                         if (!opts->merge)
268                                 return 1;
269                         parse_commit(old->commit);
270
271                         /* Do more real merge */
272
273                         /*
274                          * We update the index fully, then write the
275                          * tree from the index, then merge the new
276                          * branch with the current tree, with the old
277                          * branch as the base. Then we reset the index
278                          * (but not the working tree) to the new
279                          * branch, leaving the working tree as the
280                          * merged version, but skipping unmerged
281                          * entries in the index.
282                          */
283
284                         add_files_to_cache(NULL, NULL, 0);
285                         work = write_tree_from_memory();
286
287                         ret = reset_tree(new->commit->tree, opts, 1);
288                         if (ret)
289                                 return ret;
290                         merge_trees(new->commit->tree, work, old->commit->tree,
291                                     new->name, "local", &result);
292                         ret = reset_tree(new->commit->tree, opts, 0);
293                         if (ret)
294                                 return ret;
295                 }
296         }
297
298         if (write_cache(newfd, active_cache, active_nr) ||
299             commit_locked_index(lock_file))
300                 die("unable to write new index file");
301
302         if (!opts->force)
303                 show_local_changes(&new->commit->object);
304
305         return 0;
306 }
307
308 static void report_tracking(struct branch_info *new)
309 {
310         struct strbuf sb = STRBUF_INIT;
311         struct branch *branch = branch_get(new->name);
312
313         if (!format_tracking_info(branch, &sb))
314                 return;
315         fputs(sb.buf, stdout);
316         strbuf_release(&sb);
317 }
318
319 static void update_refs_for_switch(struct checkout_opts *opts,
320                                    struct branch_info *old,
321                                    struct branch_info *new)
322 {
323         struct strbuf msg;
324         const char *old_desc;
325         if (opts->new_branch) {
326                 create_branch(old->name, opts->new_branch, new->name, 0,
327                               opts->new_branch_log, opts->track);
328                 new->name = opts->new_branch;
329                 setup_branch_path(new);
330         }
331
332         strbuf_init(&msg, 0);
333         old_desc = old->name;
334         if (!old_desc)
335                 old_desc = sha1_to_hex(old->commit->object.sha1);
336         strbuf_addf(&msg, "checkout: moving from %s to %s",
337                     old_desc, new->name);
338
339         if (new->path) {
340                 create_symref("HEAD", new->path, msg.buf);
341                 if (!opts->quiet) {
342                         if (old->path && !strcmp(new->path, old->path))
343                                 fprintf(stderr, "Already on \"%s\"\n",
344                                         new->name);
345                         else
346                                 fprintf(stderr, "Switched to%s branch \"%s\"\n",
347                                         opts->new_branch ? " a new" : "",
348                                         new->name);
349                 }
350         } else if (strcmp(new->name, "HEAD")) {
351                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
352                            REF_NODEREF, DIE_ON_ERR);
353                 if (!opts->quiet) {
354                         if (old->path)
355                                 fprintf(stderr, "Note: moving to \"%s\" which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n  git checkout -b <new_branch_name>\n", new->name);
356                         describe_detached_head("HEAD is now at", new->commit);
357                 }
358         }
359         remove_branch_state();
360         strbuf_release(&msg);
361         if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
362                 report_tracking(new);
363 }
364
365 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
366 {
367         int ret = 0;
368         struct branch_info old;
369         unsigned char rev[20];
370         int flag;
371         memset(&old, 0, sizeof(old));
372         old.path = resolve_ref("HEAD", rev, 0, &flag);
373         old.commit = lookup_commit_reference_gently(rev, 1);
374         if (!(flag & REF_ISSYMREF))
375                 old.path = NULL;
376
377         if (old.path && !prefixcmp(old.path, "refs/heads/"))
378                 old.name = old.path + strlen("refs/heads/");
379
380         if (!new->name) {
381                 new->name = "HEAD";
382                 new->commit = old.commit;
383                 if (!new->commit)
384                         die("You are on a branch yet to be born");
385                 parse_commit(new->commit);
386         }
387
388         /*
389          * If the new thing isn't a branch and isn't HEAD and we're
390          * not starting a new branch, and we want messages, and we
391          * weren't on a branch, and we're moving to a new commit,
392          * describe the old commit.
393          */
394         if (!new->path && strcmp(new->name, "HEAD") && !opts->new_branch &&
395             !opts->quiet && !old.path && new->commit != old.commit)
396                 describe_detached_head("Previous HEAD position was", old.commit);
397
398         if (!old.commit) {
399                 if (!opts->quiet) {
400                         fprintf(stderr, "warning: You appear to be on a branch yet to be born.\n");
401                         fprintf(stderr, "warning: Forcing checkout of %s.\n", new->name);
402                 }
403                 opts->force = 1;
404         }
405
406         ret = merge_working_tree(opts, &old, new);
407         if (ret)
408                 return ret;
409
410         update_refs_for_switch(opts, &old, new);
411
412         ret = post_checkout_hook(old.commit, new->commit, 1);
413         return ret || opts->writeout_error;
414 }
415
416 int cmd_checkout(int argc, const char **argv, const char *prefix)
417 {
418         struct checkout_opts opts;
419         unsigned char rev[20];
420         const char *arg;
421         struct branch_info new;
422         struct tree *source_tree = NULL;
423         struct option options[] = {
424                 OPT__QUIET(&opts.quiet),
425                 OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
426                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
427                 OPT_SET_INT('t', "track",  &opts.track, "track",
428                         BRANCH_TRACK_EXPLICIT),
429                 OPT_BOOLEAN('f', NULL, &opts.force, "force"),
430                 OPT_BOOLEAN('m', NULL, &opts.merge, "merge"),
431                 OPT_END(),
432         };
433         int has_dash_dash;
434
435         memset(&opts, 0, sizeof(opts));
436         memset(&new, 0, sizeof(new));
437
438         git_config(git_default_config, NULL);
439
440         opts.track = BRANCH_TRACK_UNSPECIFIED;
441
442         argc = parse_options(argc, argv, options, checkout_usage,
443                              PARSE_OPT_KEEP_DASHDASH);
444
445         /* --track without -b should DWIM */
446         if (0 < opts.track && !opts.new_branch) {
447                 const char *argv0 = argv[0];
448                 if (!argc || !strcmp(argv0, "--"))
449                         die ("--track needs a branch name");
450                 if (!prefixcmp(argv0, "refs/"))
451                         argv0 += 5;
452                 if (!prefixcmp(argv0, "remotes/"))
453                         argv0 += 8;
454                 argv0 = strchr(argv0, '/');
455                 if (!argv0 || !argv0[1])
456                         die ("Missing branch name; try -b");
457                 opts.new_branch = argv0 + 1;
458         }
459
460         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
461                 opts.track = git_branch_track;
462
463         if (opts.force && opts.merge)
464                 die("git checkout: -f and -m are incompatible");
465
466         /*
467          * case 1: git checkout <ref> -- [<paths>]
468          *
469          *   <ref> must be a valid tree, everything after the '--' must be
470          *   a path.
471          *
472          * case 2: git checkout -- [<paths>]
473          *
474          *   everything after the '--' must be paths.
475          *
476          * case 3: git checkout <something> [<paths>]
477          *
478          *   With no paths, if <something> is a commit, that is to
479          *   switch to the branch or detach HEAD at it.
480          *
481          *   Otherwise <something> shall not be ambiguous.
482          *   - If it's *only* a reference, treat it like case (1).
483          *   - If it's only a path, treat it like case (2).
484          *   - else: fail.
485          *
486          */
487         if (argc) {
488                 if (!strcmp(argv[0], "--")) {       /* case (2) */
489                         argv++;
490                         argc--;
491                         goto no_reference;
492                 }
493
494                 arg = argv[0];
495                 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
496
497                 if (get_sha1(arg, rev)) {
498                         if (has_dash_dash)          /* case (1) */
499                                 die("invalid reference: %s", arg);
500                         goto no_reference;          /* case (3 -> 2) */
501                 }
502
503                 /* we can't end up being in (2) anymore, eat the argument */
504                 argv++;
505                 argc--;
506
507                 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
508                         new.name = arg;
509                         setup_branch_path(&new);
510                         if (resolve_ref(new.path, rev, 1, NULL))
511                                 new.commit = lookup_commit_reference(rev);
512                         else
513                                 new.path = NULL;
514                         parse_commit(new.commit);
515                         source_tree = new.commit->tree;
516                 } else
517                         source_tree = parse_tree_indirect(rev);
518
519                 if (!source_tree)                   /* case (1): want a tree */
520                         die("reference is not a tree: %s", arg);
521                 if (!has_dash_dash) {/* case (3 -> 1) */
522                         /*
523                          * Do not complain the most common case
524                          *      git checkout branch
525                          * even if there happen to be a file called 'branch';
526                          * it would be extremely annoying.
527                          */
528                         if (argc)
529                                 verify_non_filename(NULL, arg);
530                 }
531                 else {
532                         argv++;
533                         argc--;
534                 }
535         }
536
537 no_reference:
538         if (argc) {
539                 const char **pathspec = get_pathspec(prefix, argv);
540
541                 if (!pathspec)
542                         die("invalid path specification");
543
544                 /* Checkout paths */
545                 if (opts.new_branch || opts.force || opts.merge) {
546                         if (argc == 1) {
547                                 die("git checkout: updating paths is incompatible with switching branches/forcing\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
548                         } else {
549                                 die("git checkout: updating paths is incompatible with switching branches/forcing");
550                         }
551                 }
552
553                 return checkout_paths(source_tree, pathspec);
554         }
555
556         if (new.name && !new.commit) {
557                 die("Cannot switch branch to a non-commit.");
558         }
559
560         return switch_branches(&opts, &new);
561 }