Merge branch 'jk/update-links-in-docs'
[git] / builtin / replace.c
1 /*
2  * Builtin "git replace"
3  *
4  * Copyright (c) 2008 Christian Couder <chriscool@tuxfamily.org>
5  *
6  * Based on builtin/tag.c by Kristian Høgsberg <krh@redhat.com>
7  * and Carlos Rica <jasampler@gmail.com> that was itself based on
8  * git-tag.sh and mktag.c by Linus Torvalds.
9  */
10
11 #include "cache.h"
12 #include "builtin.h"
13 #include "refs.h"
14 #include "parse-options.h"
15 #include "run-command.h"
16 #include "tag.h"
17
18 static const char * const git_replace_usage[] = {
19         N_("git replace [-f] <object> <replacement>"),
20         N_("git replace [-f] --edit <object>"),
21         N_("git replace [-f] --graft <commit> [<parent>...]"),
22         N_("git replace -d <object>..."),
23         N_("git replace [--format=<format>] [-l [<pattern>]]"),
24         NULL
25 };
26
27 enum replace_format {
28         REPLACE_FORMAT_SHORT,
29         REPLACE_FORMAT_MEDIUM,
30         REPLACE_FORMAT_LONG
31 };
32
33 struct show_data {
34         const char *pattern;
35         enum replace_format format;
36 };
37
38 static int show_reference(const char *refname, const struct object_id *oid,
39                           int flag, void *cb_data)
40 {
41         struct show_data *data = cb_data;
42
43         if (!wildmatch(data->pattern, refname, 0, NULL)) {
44                 if (data->format == REPLACE_FORMAT_SHORT)
45                         printf("%s\n", refname);
46                 else if (data->format == REPLACE_FORMAT_MEDIUM)
47                         printf("%s -> %s\n", refname, oid_to_hex(oid));
48                 else { /* data->format == REPLACE_FORMAT_LONG */
49                         struct object_id object;
50                         enum object_type obj_type, repl_type;
51
52                         if (get_sha1(refname, object.hash))
53                                 return error("Failed to resolve '%s' as a valid ref.", refname);
54
55                         obj_type = sha1_object_info(object.hash, NULL);
56                         repl_type = sha1_object_info(oid->hash, NULL);
57
58                         printf("%s (%s) -> %s (%s)\n", refname, typename(obj_type),
59                                oid_to_hex(oid), typename(repl_type));
60                 }
61         }
62
63         return 0;
64 }
65
66 static int list_replace_refs(const char *pattern, const char *format)
67 {
68         struct show_data data;
69
70         if (pattern == NULL)
71                 pattern = "*";
72         data.pattern = pattern;
73
74         if (format == NULL || *format == '\0' || !strcmp(format, "short"))
75                 data.format = REPLACE_FORMAT_SHORT;
76         else if (!strcmp(format, "medium"))
77                 data.format = REPLACE_FORMAT_MEDIUM;
78         else if (!strcmp(format, "long"))
79                 data.format = REPLACE_FORMAT_LONG;
80         else
81                 die("invalid replace format '%s'\n"
82                     "valid formats are 'short', 'medium' and 'long'\n",
83                     format);
84
85         for_each_replace_ref(show_reference, (void *)&data);
86
87         return 0;
88 }
89
90 typedef int (*each_replace_name_fn)(const char *name, const char *ref,
91                                     const struct object_id *oid);
92
93 static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
94 {
95         const char **p, *full_hex;
96         struct strbuf ref = STRBUF_INIT;
97         size_t base_len;
98         int had_error = 0;
99         struct object_id oid;
100
101         strbuf_addstr(&ref, git_replace_ref_base);
102         base_len = ref.len;
103
104         for (p = argv; *p; p++) {
105                 if (get_oid(*p, &oid)) {
106                         error("Failed to resolve '%s' as a valid ref.", *p);
107                         had_error = 1;
108                         continue;
109                 }
110
111                 strbuf_setlen(&ref, base_len);
112                 strbuf_addstr(&ref, oid_to_hex(&oid));
113                 full_hex = ref.buf + base_len;
114
115                 if (read_ref(ref.buf, oid.hash)) {
116                         error("replace ref '%s' not found.", full_hex);
117                         had_error = 1;
118                         continue;
119                 }
120                 if (fn(full_hex, ref.buf, &oid))
121                         had_error = 1;
122         }
123         strbuf_release(&ref);
124         return had_error;
125 }
126
127 static int delete_replace_ref(const char *name, const char *ref,
128                               const struct object_id *oid)
129 {
130         if (delete_ref(NULL, ref, oid->hash, 0))
131                 return 1;
132         printf("Deleted replace ref '%s'\n", name);
133         return 0;
134 }
135
136 static void check_ref_valid(struct object_id *object,
137                             struct object_id *prev,
138                             struct strbuf *ref,
139                             int force)
140 {
141         strbuf_reset(ref);
142         strbuf_addf(ref, "%s%s", git_replace_ref_base, oid_to_hex(object));
143         if (check_refname_format(ref->buf, 0))
144                 die("'%s' is not a valid ref name.", ref->buf);
145
146         if (read_ref(ref->buf, prev->hash))
147                 oidclr(prev);
148         else if (!force)
149                 die("replace ref '%s' already exists", ref->buf);
150 }
151
152 static int replace_object_oid(const char *object_ref,
153                                struct object_id *object,
154                                const char *replace_ref,
155                                struct object_id *repl,
156                                int force)
157 {
158         struct object_id prev;
159         enum object_type obj_type, repl_type;
160         struct strbuf ref = STRBUF_INIT;
161         struct ref_transaction *transaction;
162         struct strbuf err = STRBUF_INIT;
163
164         obj_type = sha1_object_info(object->hash, NULL);
165         repl_type = sha1_object_info(repl->hash, NULL);
166         if (!force && obj_type != repl_type)
167                 die("Objects must be of the same type.\n"
168                     "'%s' points to a replaced object of type '%s'\n"
169                     "while '%s' points to a replacement object of type '%s'.",
170                     object_ref, typename(obj_type),
171                     replace_ref, typename(repl_type));
172
173         check_ref_valid(object, &prev, &ref, force);
174
175         transaction = ref_transaction_begin(&err);
176         if (!transaction ||
177             ref_transaction_update(transaction, ref.buf, repl->hash, prev.hash,
178                                    0, NULL, &err) ||
179             ref_transaction_commit(transaction, &err))
180                 die("%s", err.buf);
181
182         ref_transaction_free(transaction);
183         strbuf_release(&ref);
184         return 0;
185 }
186
187 static int replace_object(const char *object_ref, const char *replace_ref, int force)
188 {
189         struct object_id object, repl;
190
191         if (get_oid(object_ref, &object))
192                 die("Failed to resolve '%s' as a valid ref.", object_ref);
193         if (get_oid(replace_ref, &repl))
194                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
195
196         return replace_object_oid(object_ref, &object, replace_ref, &repl, force);
197 }
198
199 /*
200  * Write the contents of the object named by "sha1" to the file "filename".
201  * If "raw" is true, then the object's raw contents are printed according to
202  * "type". Otherwise, we pretty-print the contents for human editing.
203  */
204 static void export_object(const struct object_id *oid, enum object_type type,
205                           int raw, const char *filename)
206 {
207         struct child_process cmd = CHILD_PROCESS_INIT;
208         int fd;
209
210         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
211         if (fd < 0)
212                 die_errno("unable to open %s for writing", filename);
213
214         argv_array_push(&cmd.args, "--no-replace-objects");
215         argv_array_push(&cmd.args, "cat-file");
216         if (raw)
217                 argv_array_push(&cmd.args, typename(type));
218         else
219                 argv_array_push(&cmd.args, "-p");
220         argv_array_push(&cmd.args, oid_to_hex(oid));
221         cmd.git_cmd = 1;
222         cmd.out = fd;
223
224         if (run_command(&cmd))
225                 die("cat-file reported failure");
226 }
227
228 /*
229  * Read a previously-exported (and possibly edited) object back from "filename",
230  * interpreting it as "type", and writing the result to the object database.
231  * The sha1 of the written object is returned via sha1.
232  */
233 static void import_object(struct object_id *oid, enum object_type type,
234                           int raw, const char *filename)
235 {
236         int fd;
237
238         fd = open(filename, O_RDONLY);
239         if (fd < 0)
240                 die_errno("unable to open %s for reading", filename);
241
242         if (!raw && type == OBJ_TREE) {
243                 const char *argv[] = { "mktree", NULL };
244                 struct child_process cmd = CHILD_PROCESS_INIT;
245                 struct strbuf result = STRBUF_INIT;
246
247                 cmd.argv = argv;
248                 cmd.git_cmd = 1;
249                 cmd.in = fd;
250                 cmd.out = -1;
251
252                 if (start_command(&cmd))
253                         die("unable to spawn mktree");
254
255                 if (strbuf_read(&result, cmd.out, 41) < 0)
256                         die_errno("unable to read from mktree");
257                 close(cmd.out);
258
259                 if (finish_command(&cmd))
260                         die("mktree reported failure");
261                 if (get_oid_hex(result.buf, oid) < 0)
262                         die("mktree did not return an object name");
263
264                 strbuf_release(&result);
265         } else {
266                 struct stat st;
267                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
268
269                 if (fstat(fd, &st) < 0)
270                         die_errno("unable to fstat %s", filename);
271                 if (index_fd(oid->hash, fd, &st, type, NULL, flags) < 0)
272                         die("unable to write object to database");
273                 /* index_fd close()s fd for us */
274         }
275
276         /*
277          * No need to close(fd) here; both run-command and index-fd
278          * will have done it for us.
279          */
280 }
281
282 static int edit_and_replace(const char *object_ref, int force, int raw)
283 {
284         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
285         enum object_type type;
286         struct object_id old, new, prev;
287         struct strbuf ref = STRBUF_INIT;
288
289         if (get_oid(object_ref, &old) < 0)
290                 die("Not a valid object name: '%s'", object_ref);
291
292         type = sha1_object_info(old.hash, NULL);
293         if (type < 0)
294                 die("unable to get object type for %s", oid_to_hex(&old));
295
296         check_ref_valid(&old, &prev, &ref, force);
297         strbuf_release(&ref);
298
299         export_object(&old, type, raw, tmpfile);
300         if (launch_editor(tmpfile, NULL, NULL) < 0)
301                 die("editing object file failed");
302         import_object(&new, type, raw, tmpfile);
303
304         free(tmpfile);
305
306         if (!oidcmp(&old, &new))
307                 return error("new object is the same as the old one: '%s'", oid_to_hex(&old));
308
309         return replace_object_oid(object_ref, &old, "replacement", &new, force);
310 }
311
312 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
313 {
314         struct strbuf new_parents = STRBUF_INIT;
315         const char *parent_start, *parent_end;
316         int i;
317
318         /* find existing parents */
319         parent_start = buf->buf;
320         parent_start += GIT_SHA1_HEXSZ + 6; /* "tree " + "hex sha1" + "\n" */
321         parent_end = parent_start;
322
323         while (starts_with(parent_end, "parent "))
324                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
325
326         /* prepare new parents */
327         for (i = 0; i < argc; i++) {
328                 struct object_id oid;
329                 if (get_oid(argv[i], &oid) < 0)
330                         die(_("Not a valid object name: '%s'"), argv[i]);
331                 lookup_commit_or_die(&oid, argv[i]);
332                 strbuf_addf(&new_parents, "parent %s\n", oid_to_hex(&oid));
333         }
334
335         /* replace existing parents with new ones */
336         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
337                       new_parents.buf, new_parents.len);
338
339         strbuf_release(&new_parents);
340 }
341
342 struct check_mergetag_data {
343         int argc;
344         const char **argv;
345 };
346
347 static void check_one_mergetag(struct commit *commit,
348                                struct commit_extra_header *extra,
349                                void *data)
350 {
351         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
352         const char *ref = mergetag_data->argv[0];
353         struct object_id tag_oid;
354         struct tag *tag;
355         int i;
356
357         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_oid.hash);
358         tag = lookup_tag(&tag_oid);
359         if (!tag)
360                 die(_("bad mergetag in commit '%s'"), ref);
361         if (parse_tag_buffer(tag, extra->value, extra->len))
362                 die(_("malformed mergetag in commit '%s'"), ref);
363
364         /* iterate over new parents */
365         for (i = 1; i < mergetag_data->argc; i++) {
366                 struct object_id oid;
367                 if (get_sha1(mergetag_data->argv[i], oid.hash) < 0)
368                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
369                 if (!oidcmp(&tag->tagged->oid, &oid))
370                         return; /* found */
371         }
372
373         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
374               "use --edit instead of --graft"), ref, oid_to_hex(&tag_oid));
375 }
376
377 static void check_mergetags(struct commit *commit, int argc, const char **argv)
378 {
379         struct check_mergetag_data mergetag_data;
380
381         mergetag_data.argc = argc;
382         mergetag_data.argv = argv;
383         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
384 }
385
386 static int create_graft(int argc, const char **argv, int force)
387 {
388         struct object_id old, new;
389         const char *old_ref = argv[0];
390         struct commit *commit;
391         struct strbuf buf = STRBUF_INIT;
392         const char *buffer;
393         unsigned long size;
394
395         if (get_oid(old_ref, &old) < 0)
396                 die(_("Not a valid object name: '%s'"), old_ref);
397         commit = lookup_commit_or_die(&old, old_ref);
398
399         buffer = get_commit_buffer(commit, &size);
400         strbuf_add(&buf, buffer, size);
401         unuse_commit_buffer(commit, buffer);
402
403         replace_parents(&buf, argc - 1, &argv[1]);
404
405         if (remove_signature(&buf)) {
406                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
407                 warning(_("the signature will be removed in the replacement commit!"));
408         }
409
410         check_mergetags(commit, argc, argv);
411
412         if (write_sha1_file(buf.buf, buf.len, commit_type, new.hash))
413                 die(_("could not write replacement commit for: '%s'"), old_ref);
414
415         strbuf_release(&buf);
416
417         if (!oidcmp(&old, &new))
418                 return error("new commit is the same as the old one: '%s'", oid_to_hex(&old));
419
420         return replace_object_oid(old_ref, &old, "replacement", &new, force);
421 }
422
423 int cmd_replace(int argc, const char **argv, const char *prefix)
424 {
425         int force = 0;
426         int raw = 0;
427         const char *format = NULL;
428         enum {
429                 MODE_UNSPECIFIED = 0,
430                 MODE_LIST,
431                 MODE_DELETE,
432                 MODE_EDIT,
433                 MODE_GRAFT,
434                 MODE_REPLACE
435         } cmdmode = MODE_UNSPECIFIED;
436         struct option options[] = {
437                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
438                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
439                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
440                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
441                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
442                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
443                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
444                 OPT_END()
445         };
446
447         check_replace_refs = 0;
448         git_config(git_default_config, NULL);
449
450         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
451
452         if (!cmdmode)
453                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
454
455         if (format && cmdmode != MODE_LIST)
456                 usage_msg_opt("--format cannot be used when not listing",
457                               git_replace_usage, options);
458
459         if (force &&
460             cmdmode != MODE_REPLACE &&
461             cmdmode != MODE_EDIT &&
462             cmdmode != MODE_GRAFT)
463                 usage_msg_opt("-f only makes sense when writing a replacement",
464                               git_replace_usage, options);
465
466         if (raw && cmdmode != MODE_EDIT)
467                 usage_msg_opt("--raw only makes sense with --edit",
468                               git_replace_usage, options);
469
470         switch (cmdmode) {
471         case MODE_DELETE:
472                 if (argc < 1)
473                         usage_msg_opt("-d needs at least one argument",
474                                       git_replace_usage, options);
475                 return for_each_replace_name(argv, delete_replace_ref);
476
477         case MODE_REPLACE:
478                 if (argc != 2)
479                         usage_msg_opt("bad number of arguments",
480                                       git_replace_usage, options);
481                 return replace_object(argv[0], argv[1], force);
482
483         case MODE_EDIT:
484                 if (argc != 1)
485                         usage_msg_opt("-e needs exactly one argument",
486                                       git_replace_usage, options);
487                 return edit_and_replace(argv[0], force, raw);
488
489         case MODE_GRAFT:
490                 if (argc < 1)
491                         usage_msg_opt("-g needs at least one argument",
492                                       git_replace_usage, options);
493                 return create_graft(argc, argv, force);
494
495         case MODE_LIST:
496                 if (argc > 1)
497                         usage_msg_opt("only one pattern can be given with -l",
498                                       git_replace_usage, options);
499                 return list_replace_refs(argv[0], format);
500
501         default:
502                 die("BUG: invalid cmdmode %d", (int)cmdmode);
503         }
504 }