checkout: Don't crash when switching away from an invalid branch.
[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 ? old->object.sha1 : null_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 skip_same_name(struct cache_entry *ce, int pos)
80 {
81         while (++pos < active_nr &&
82                !strcmp(active_cache[pos]->name, ce->name))
83                 ; /* skip */
84         return pos;
85 }
86
87
88 static int checkout_paths(struct tree *source_tree, const char **pathspec)
89 {
90         int pos;
91         struct checkout state;
92         static char *ps_matched;
93         unsigned char rev[20];
94         int flag;
95         struct commit *head;
96         int errs = 0;
97
98         int newfd;
99         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
100
101         newfd = hold_locked_index(lock_file, 1);
102         read_cache();
103
104         if (source_tree)
105                 read_tree_some(source_tree, pathspec);
106
107         for (pos = 0; pathspec[pos]; pos++)
108                 ;
109         ps_matched = xcalloc(1, pos);
110
111         for (pos = 0; pos < active_nr; pos++) {
112                 struct cache_entry *ce = active_cache[pos];
113                 pathspec_match(pathspec, ps_matched, ce->name, 0);
114         }
115
116         if (report_path_error(ps_matched, pathspec, 0))
117                 return 1;
118
119         /* Any unmerged paths? */
120         for (pos = 0; pos < active_nr; pos++) {
121                 struct cache_entry *ce = active_cache[pos];
122                 if (pathspec_match(pathspec, NULL, ce->name, 0)) {
123                         if (!ce_stage(ce))
124                                 continue;
125                         errs = 1;
126                         error("path '%s' is unmerged", ce->name);
127                         pos = skip_same_name(ce, pos) - 1;
128                 }
129         }
130         if (errs)
131                 return 1;
132
133         /* Now we are committed to check them out */
134         memset(&state, 0, sizeof(state));
135         state.force = 1;
136         state.refresh_cache = 1;
137         for (pos = 0; pos < active_nr; pos++) {
138                 struct cache_entry *ce = active_cache[pos];
139                 if (pathspec_match(pathspec, NULL, ce->name, 0)) {
140                         if (!ce_stage(ce)) {
141                                 errs |= checkout_entry(ce, &state, NULL);
142                                 continue;
143                         }
144                         pos = skip_same_name(ce, pos) - 1;
145                 }
146         }
147
148         if (write_cache(newfd, active_cache, active_nr) ||
149             commit_locked_index(lock_file))
150                 die("unable to write new index file");
151
152         resolve_ref("HEAD", rev, 0, &flag);
153         head = lookup_commit_reference_gently(rev, 1);
154
155         errs |= post_checkout_hook(head, head, 0);
156         return errs;
157 }
158
159 static void show_local_changes(struct object *head)
160 {
161         struct rev_info rev;
162         /* I think we want full paths, even if we're in a subdirectory. */
163         init_revisions(&rev, NULL);
164         rev.abbrev = 0;
165         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
166         add_pending_object(&rev, head, NULL);
167         run_diff_index(&rev, 0);
168 }
169
170 static void describe_detached_head(char *msg, struct commit *commit)
171 {
172         struct strbuf sb;
173         strbuf_init(&sb, 0);
174         parse_commit(commit);
175         pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
176         fprintf(stderr, "%s %s... %s\n", msg,
177                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
178         strbuf_release(&sb);
179 }
180
181 struct checkout_opts {
182         int quiet;
183         int merge;
184         int force;
185         int writeout_error;
186
187         char *new_branch;
188         int new_branch_log;
189         enum branch_track track;
190 };
191
192 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
193 {
194         struct unpack_trees_options opts;
195         struct tree_desc tree_desc;
196
197         memset(&opts, 0, sizeof(opts));
198         opts.head_idx = -1;
199         opts.update = worktree;
200         opts.skip_unmerged = !worktree;
201         opts.reset = 1;
202         opts.merge = 1;
203         opts.fn = oneway_merge;
204         opts.verbose_update = !o->quiet;
205         opts.src_index = &the_index;
206         opts.dst_index = &the_index;
207         parse_tree(tree);
208         init_tree_desc(&tree_desc, tree->buffer, tree->size);
209         switch (unpack_trees(1, &tree_desc, &opts)) {
210         case -2:
211                 o->writeout_error = 1;
212                 /*
213                  * We return 0 nevertheless, as the index is all right
214                  * and more importantly we have made best efforts to
215                  * update paths in the work tree, and we cannot revert
216                  * them.
217                  */
218         case 0:
219                 return 0;
220         default:
221                 return 128;
222         }
223 }
224
225 struct branch_info {
226         const char *name; /* The short name used */
227         const char *path; /* The full name of a real branch */
228         struct commit *commit; /* The named commit */
229 };
230
231 static void setup_branch_path(struct branch_info *branch)
232 {
233         struct strbuf buf;
234         strbuf_init(&buf, 0);
235         strbuf_addstr(&buf, "refs/heads/");
236         strbuf_addstr(&buf, branch->name);
237         branch->path = strbuf_detach(&buf, NULL);
238 }
239
240 static int merge_working_tree(struct checkout_opts *opts,
241                               struct branch_info *old, struct branch_info *new)
242 {
243         int ret;
244         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
245         int newfd = hold_locked_index(lock_file, 1);
246         read_cache();
247
248         if (opts->force) {
249                 ret = reset_tree(new->commit->tree, opts, 1);
250                 if (ret)
251                         return ret;
252         } else {
253                 struct tree_desc trees[2];
254                 struct tree *tree;
255                 struct unpack_trees_options topts;
256
257                 memset(&topts, 0, sizeof(topts));
258                 topts.head_idx = -1;
259                 topts.src_index = &the_index;
260                 topts.dst_index = &the_index;
261
262                 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
263
264                 refresh_cache(REFRESH_QUIET);
265
266                 if (unmerged_cache()) {
267                         error("you need to resolve your current index first");
268                         return 1;
269                 }
270
271                 /* 2-way merge to the new branch */
272                 topts.initial_checkout = (!active_nr &&
273                                           (old->commit == new->commit));
274                 topts.update = 1;
275                 topts.merge = 1;
276                 topts.gently = opts->merge;
277                 topts.verbose_update = !opts->quiet;
278                 topts.fn = twoway_merge;
279                 topts.dir = xcalloc(1, sizeof(*topts.dir));
280                 topts.dir->show_ignored = 1;
281                 topts.dir->exclude_per_dir = ".gitignore";
282                 tree = parse_tree_indirect(old->commit->object.sha1);
283                 init_tree_desc(&trees[0], tree->buffer, tree->size);
284                 tree = parse_tree_indirect(new->commit->object.sha1);
285                 init_tree_desc(&trees[1], tree->buffer, tree->size);
286
287                 ret = unpack_trees(2, trees, &topts);
288                 if (ret == -1) {
289                         /*
290                          * Unpack couldn't do a trivial merge; either
291                          * give up or do a real merge, depending on
292                          * whether the merge flag was used.
293                          */
294                         struct tree *result;
295                         struct tree *work;
296                         if (!opts->merge)
297                                 return 1;
298                         parse_commit(old->commit);
299
300                         /* Do more real merge */
301
302                         /*
303                          * We update the index fully, then write the
304                          * tree from the index, then merge the new
305                          * branch with the current tree, with the old
306                          * branch as the base. Then we reset the index
307                          * (but not the working tree) to the new
308                          * branch, leaving the working tree as the
309                          * merged version, but skipping unmerged
310                          * entries in the index.
311                          */
312
313                         add_files_to_cache(NULL, NULL, 0);
314                         work = write_tree_from_memory();
315
316                         ret = reset_tree(new->commit->tree, opts, 1);
317                         if (ret)
318                                 return ret;
319                         merge_trees(new->commit->tree, work, old->commit->tree,
320                                     new->name, "local", &result);
321                         ret = reset_tree(new->commit->tree, opts, 0);
322                         if (ret)
323                                 return ret;
324                 }
325         }
326
327         if (write_cache(newfd, active_cache, active_nr) ||
328             commit_locked_index(lock_file))
329                 die("unable to write new index file");
330
331         if (!opts->force && !opts->quiet)
332                 show_local_changes(&new->commit->object);
333
334         return 0;
335 }
336
337 static void report_tracking(struct branch_info *new)
338 {
339         struct strbuf sb = STRBUF_INIT;
340         struct branch *branch = branch_get(new->name);
341
342         if (!format_tracking_info(branch, &sb))
343                 return;
344         fputs(sb.buf, stdout);
345         strbuf_release(&sb);
346 }
347
348 static void update_refs_for_switch(struct checkout_opts *opts,
349                                    struct branch_info *old,
350                                    struct branch_info *new)
351 {
352         struct strbuf msg;
353         const char *old_desc;
354         if (opts->new_branch) {
355                 create_branch(old->name, opts->new_branch, new->name, 0,
356                               opts->new_branch_log, opts->track);
357                 new->name = opts->new_branch;
358                 setup_branch_path(new);
359         }
360
361         strbuf_init(&msg, 0);
362         old_desc = old->name;
363         if (!old_desc && old->commit)
364                 old_desc = sha1_to_hex(old->commit->object.sha1);
365         strbuf_addf(&msg, "checkout: moving from %s to %s",
366                     old_desc ? old_desc : "(invalid)", new->name);
367
368         if (new->path) {
369                 create_symref("HEAD", new->path, msg.buf);
370                 if (!opts->quiet) {
371                         if (old->path && !strcmp(new->path, old->path))
372                                 fprintf(stderr, "Already on \"%s\"\n",
373                                         new->name);
374                         else
375                                 fprintf(stderr, "Switched to%s branch \"%s\"\n",
376                                         opts->new_branch ? " a new" : "",
377                                         new->name);
378                 }
379         } else if (strcmp(new->name, "HEAD")) {
380                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
381                            REF_NODEREF, DIE_ON_ERR);
382                 if (!opts->quiet) {
383                         if (old->path)
384                                 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);
385                         describe_detached_head("HEAD is now at", new->commit);
386                 }
387         }
388         remove_branch_state();
389         strbuf_release(&msg);
390         if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
391                 report_tracking(new);
392 }
393
394 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
395 {
396         int ret = 0;
397         struct branch_info old;
398         unsigned char rev[20];
399         int flag;
400         memset(&old, 0, sizeof(old));
401         old.path = resolve_ref("HEAD", rev, 0, &flag);
402         old.commit = lookup_commit_reference_gently(rev, 1);
403         if (!(flag & REF_ISSYMREF))
404                 old.path = NULL;
405
406         if (old.path && !prefixcmp(old.path, "refs/heads/"))
407                 old.name = old.path + strlen("refs/heads/");
408
409         if (!new->name) {
410                 new->name = "HEAD";
411                 new->commit = old.commit;
412                 if (!new->commit)
413                         die("You are on a branch yet to be born");
414                 parse_commit(new->commit);
415         }
416
417         /*
418          * If we were on a detached HEAD, but we are now moving to
419          * a new commit, we want to mention the old commit once more
420          * to remind the user that it might be lost.
421          */
422         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
423                 describe_detached_head("Previous HEAD position was", old.commit);
424
425         if (!old.commit) {
426                 if (!opts->quiet) {
427                         fprintf(stderr, "warning: You appear to be on a branch yet to be born.\n");
428                         fprintf(stderr, "warning: Forcing checkout of %s.\n", new->name);
429                 }
430                 opts->force = 1;
431         }
432
433         ret = merge_working_tree(opts, &old, new);
434         if (ret)
435                 return ret;
436
437         update_refs_for_switch(opts, &old, new);
438
439         ret = post_checkout_hook(old.commit, new->commit, 1);
440         return ret || opts->writeout_error;
441 }
442
443 int cmd_checkout(int argc, const char **argv, const char *prefix)
444 {
445         struct checkout_opts opts;
446         unsigned char rev[20];
447         const char *arg;
448         struct branch_info new;
449         struct tree *source_tree = NULL;
450         struct option options[] = {
451                 OPT__QUIET(&opts.quiet),
452                 OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
453                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
454                 OPT_SET_INT('t', "track",  &opts.track, "track",
455                         BRANCH_TRACK_EXPLICIT),
456                 OPT_BOOLEAN('f', NULL, &opts.force, "force"),
457                 OPT_BOOLEAN('m', NULL, &opts.merge, "merge"),
458                 OPT_END(),
459         };
460         int has_dash_dash;
461
462         memset(&opts, 0, sizeof(opts));
463         memset(&new, 0, sizeof(new));
464
465         git_config(git_default_config, NULL);
466
467         opts.track = git_branch_track;
468
469         argc = parse_options(argc, argv, options, checkout_usage,
470                              PARSE_OPT_KEEP_DASHDASH);
471
472         if (!opts.new_branch && (opts.track != git_branch_track))
473                 die("git checkout: --track and --no-track require -b");
474
475         if (opts.force && opts.merge)
476                 die("git checkout: -f and -m are incompatible");
477
478         /*
479          * case 1: git checkout <ref> -- [<paths>]
480          *
481          *   <ref> must be a valid tree, everything after the '--' must be
482          *   a path.
483          *
484          * case 2: git checkout -- [<paths>]
485          *
486          *   everything after the '--' must be paths.
487          *
488          * case 3: git checkout <something> [<paths>]
489          *
490          *   With no paths, if <something> is a commit, that is to
491          *   switch to the branch or detach HEAD at it.
492          *
493          *   Otherwise <something> shall not be ambiguous.
494          *   - If it's *only* a reference, treat it like case (1).
495          *   - If it's only a path, treat it like case (2).
496          *   - else: fail.
497          *
498          */
499         if (argc) {
500                 if (!strcmp(argv[0], "--")) {       /* case (2) */
501                         argv++;
502                         argc--;
503                         goto no_reference;
504                 }
505
506                 arg = argv[0];
507                 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
508
509                 if (get_sha1(arg, rev)) {
510                         if (has_dash_dash)          /* case (1) */
511                                 die("invalid reference: %s", arg);
512                         goto no_reference;          /* case (3 -> 2) */
513                 }
514
515                 /* we can't end up being in (2) anymore, eat the argument */
516                 argv++;
517                 argc--;
518
519                 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
520                         new.name = arg;
521                         setup_branch_path(&new);
522                         if (resolve_ref(new.path, rev, 1, NULL))
523                                 new.commit = lookup_commit_reference(rev);
524                         else
525                                 new.path = NULL;
526                         parse_commit(new.commit);
527                         source_tree = new.commit->tree;
528                 } else
529                         source_tree = parse_tree_indirect(rev);
530
531                 if (!source_tree)                   /* case (1): want a tree */
532                         die("reference is not a tree: %s", arg);
533                 if (!has_dash_dash) {/* case (3 -> 1) */
534                         /*
535                          * Do not complain the most common case
536                          *      git checkout branch
537                          * even if there happen to be a file called 'branch';
538                          * it would be extremely annoying.
539                          */
540                         if (argc)
541                                 verify_non_filename(NULL, arg);
542                 }
543                 else {
544                         argv++;
545                         argc--;
546                 }
547         }
548
549 no_reference:
550         if (argc) {
551                 const char **pathspec = get_pathspec(prefix, argv);
552
553                 if (!pathspec)
554                         die("invalid path specification");
555
556                 /* Checkout paths */
557                 if (opts.new_branch || opts.force || opts.merge) {
558                         if (argc == 1) {
559                                 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]);
560                         } else {
561                                 die("git checkout: updating paths is incompatible with switching branches/forcing");
562                         }
563                 }
564
565                 return checkout_paths(source_tree, pathspec);
566         }
567
568         if (opts.new_branch) {
569                 struct strbuf buf;
570                 strbuf_init(&buf, 0);
571                 strbuf_addstr(&buf, "refs/heads/");
572                 strbuf_addstr(&buf, opts.new_branch);
573                 if (!get_sha1(buf.buf, rev))
574                         die("git checkout: branch %s already exists", opts.new_branch);
575                 if (check_ref_format(buf.buf))
576                         die("git checkout: we do not like '%s' as a branch name.", opts.new_branch);
577                 strbuf_release(&buf);
578         }
579
580         if (new.name && !new.commit) {
581                 die("Cannot switch branch to a non-commit.");
582         }
583
584         return switch_branches(&opts, &new);
585 }