Merge branch 'jk/pack-idx-corruption-safety' into maint
[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 unsigned char *sha1);
92
93 static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
94 {
95         const char **p, *full_hex;
96         char ref[PATH_MAX];
97         int had_error = 0;
98         unsigned char sha1[20];
99
100         for (p = argv; *p; p++) {
101                 if (get_sha1(*p, sha1)) {
102                         error("Failed to resolve '%s' as a valid ref.", *p);
103                         had_error = 1;
104                         continue;
105                 }
106                 full_hex = sha1_to_hex(sha1);
107                 snprintf(ref, sizeof(ref), "%s%s", git_replace_ref_base, full_hex);
108                 /* read_ref() may reuse the buffer */
109                 full_hex = ref + strlen(git_replace_ref_base);
110                 if (read_ref(ref, sha1)) {
111                         error("replace ref '%s' not found.", full_hex);
112                         had_error = 1;
113                         continue;
114                 }
115                 if (fn(full_hex, ref, sha1))
116                         had_error = 1;
117         }
118         return had_error;
119 }
120
121 static int delete_replace_ref(const char *name, const char *ref,
122                               const unsigned char *sha1)
123 {
124         if (delete_ref(ref, sha1, 0))
125                 return 1;
126         printf("Deleted replace ref '%s'\n", name);
127         return 0;
128 }
129
130 static void check_ref_valid(unsigned char object[20],
131                             unsigned char prev[20],
132                             char *ref,
133                             int ref_size,
134                             int force)
135 {
136         if (snprintf(ref, ref_size,
137                      "%s%s", git_replace_ref_base,
138                      sha1_to_hex(object)) > ref_size - 1)
139                 die("replace ref name too long: %.*s...", 50, ref);
140         if (check_refname_format(ref, 0))
141                 die("'%s' is not a valid ref name.", ref);
142
143         if (read_ref(ref, prev))
144                 hashclr(prev);
145         else if (!force)
146                 die("replace ref '%s' already exists", ref);
147 }
148
149 static int replace_object_sha1(const char *object_ref,
150                                unsigned char object[20],
151                                const char *replace_ref,
152                                unsigned char repl[20],
153                                int force)
154 {
155         unsigned char prev[20];
156         enum object_type obj_type, repl_type;
157         char ref[PATH_MAX];
158         struct ref_transaction *transaction;
159         struct strbuf err = STRBUF_INIT;
160
161         obj_type = sha1_object_info(object, NULL);
162         repl_type = sha1_object_info(repl, NULL);
163         if (!force && obj_type != repl_type)
164                 die("Objects must be of the same type.\n"
165                     "'%s' points to a replaced object of type '%s'\n"
166                     "while '%s' points to a replacement object of type '%s'.",
167                     object_ref, typename(obj_type),
168                     replace_ref, typename(repl_type));
169
170         check_ref_valid(object, prev, ref, sizeof(ref), force);
171
172         transaction = ref_transaction_begin(&err);
173         if (!transaction ||
174             ref_transaction_update(transaction, ref, repl, prev,
175                                    0, NULL, &err) ||
176             ref_transaction_commit(transaction, &err))
177                 die("%s", err.buf);
178
179         ref_transaction_free(transaction);
180         return 0;
181 }
182
183 static int replace_object(const char *object_ref, const char *replace_ref, int force)
184 {
185         unsigned char object[20], repl[20];
186
187         if (get_sha1(object_ref, object))
188                 die("Failed to resolve '%s' as a valid ref.", object_ref);
189         if (get_sha1(replace_ref, repl))
190                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
191
192         return replace_object_sha1(object_ref, object, replace_ref, repl, force);
193 }
194
195 /*
196  * Write the contents of the object named by "sha1" to the file "filename".
197  * If "raw" is true, then the object's raw contents are printed according to
198  * "type". Otherwise, we pretty-print the contents for human editing.
199  */
200 static void export_object(const unsigned char *sha1, enum object_type type,
201                           int raw, const char *filename)
202 {
203         struct child_process cmd = CHILD_PROCESS_INIT;
204         int fd;
205
206         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
207         if (fd < 0)
208                 die_errno("unable to open %s for writing", filename);
209
210         argv_array_push(&cmd.args, "--no-replace-objects");
211         argv_array_push(&cmd.args, "cat-file");
212         if (raw)
213                 argv_array_push(&cmd.args, typename(type));
214         else
215                 argv_array_push(&cmd.args, "-p");
216         argv_array_push(&cmd.args, sha1_to_hex(sha1));
217         cmd.git_cmd = 1;
218         cmd.out = fd;
219
220         if (run_command(&cmd))
221                 die("cat-file reported failure");
222 }
223
224 /*
225  * Read a previously-exported (and possibly edited) object back from "filename",
226  * interpreting it as "type", and writing the result to the object database.
227  * The sha1 of the written object is returned via sha1.
228  */
229 static void import_object(unsigned char *sha1, enum object_type type,
230                           int raw, const char *filename)
231 {
232         int fd;
233
234         fd = open(filename, O_RDONLY);
235         if (fd < 0)
236                 die_errno("unable to open %s for reading", filename);
237
238         if (!raw && type == OBJ_TREE) {
239                 const char *argv[] = { "mktree", NULL };
240                 struct child_process cmd = CHILD_PROCESS_INIT;
241                 struct strbuf result = STRBUF_INIT;
242
243                 cmd.argv = argv;
244                 cmd.git_cmd = 1;
245                 cmd.in = fd;
246                 cmd.out = -1;
247
248                 if (start_command(&cmd))
249                         die("unable to spawn mktree");
250
251                 if (strbuf_read(&result, cmd.out, 41) < 0)
252                         die_errno("unable to read from mktree");
253                 close(cmd.out);
254
255                 if (finish_command(&cmd))
256                         die("mktree reported failure");
257                 if (get_sha1_hex(result.buf, sha1) < 0)
258                         die("mktree did not return an object name");
259
260                 strbuf_release(&result);
261         } else {
262                 struct stat st;
263                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
264
265                 if (fstat(fd, &st) < 0)
266                         die_errno("unable to fstat %s", filename);
267                 if (index_fd(sha1, fd, &st, type, NULL, flags) < 0)
268                         die("unable to write object to database");
269                 /* index_fd close()s fd for us */
270         }
271
272         /*
273          * No need to close(fd) here; both run-command and index-fd
274          * will have done it for us.
275          */
276 }
277
278 static int edit_and_replace(const char *object_ref, int force, int raw)
279 {
280         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
281         enum object_type type;
282         unsigned char old[20], new[20], prev[20];
283         char ref[PATH_MAX];
284
285         if (get_sha1(object_ref, old) < 0)
286                 die("Not a valid object name: '%s'", object_ref);
287
288         type = sha1_object_info(old, NULL);
289         if (type < 0)
290                 die("unable to get object type for %s", sha1_to_hex(old));
291
292         check_ref_valid(old, prev, ref, sizeof(ref), force);
293
294         export_object(old, type, raw, tmpfile);
295         if (launch_editor(tmpfile, NULL, NULL) < 0)
296                 die("editing object file failed");
297         import_object(new, type, raw, tmpfile);
298
299         free(tmpfile);
300
301         if (!hashcmp(old, new))
302                 return error("new object is the same as the old one: '%s'", sha1_to_hex(old));
303
304         return replace_object_sha1(object_ref, old, "replacement", new, force);
305 }
306
307 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
308 {
309         struct strbuf new_parents = STRBUF_INIT;
310         const char *parent_start, *parent_end;
311         int i;
312
313         /* find existing parents */
314         parent_start = buf->buf;
315         parent_start += 46; /* "tree " + "hex sha1" + "\n" */
316         parent_end = parent_start;
317
318         while (starts_with(parent_end, "parent "))
319                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
320
321         /* prepare new parents */
322         for (i = 0; i < argc; i++) {
323                 unsigned char sha1[20];
324                 if (get_sha1(argv[i], sha1) < 0)
325                         die(_("Not a valid object name: '%s'"), argv[i]);
326                 lookup_commit_or_die(sha1, argv[i]);
327                 strbuf_addf(&new_parents, "parent %s\n", sha1_to_hex(sha1));
328         }
329
330         /* replace existing parents with new ones */
331         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
332                       new_parents.buf, new_parents.len);
333
334         strbuf_release(&new_parents);
335 }
336
337 struct check_mergetag_data {
338         int argc;
339         const char **argv;
340 };
341
342 static void check_one_mergetag(struct commit *commit,
343                                struct commit_extra_header *extra,
344                                void *data)
345 {
346         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
347         const char *ref = mergetag_data->argv[0];
348         unsigned char tag_sha1[20];
349         struct tag *tag;
350         int i;
351
352         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_sha1);
353         tag = lookup_tag(tag_sha1);
354         if (!tag)
355                 die(_("bad mergetag in commit '%s'"), ref);
356         if (parse_tag_buffer(tag, extra->value, extra->len))
357                 die(_("malformed mergetag in commit '%s'"), ref);
358
359         /* iterate over new parents */
360         for (i = 1; i < mergetag_data->argc; i++) {
361                 struct object_id oid;
362                 if (get_sha1(mergetag_data->argv[i], oid.hash) < 0)
363                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
364                 if (!oidcmp(&tag->tagged->oid, &oid))
365                         return; /* found */
366         }
367
368         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
369               "use --edit instead of --graft"), ref, sha1_to_hex(tag_sha1));
370 }
371
372 static void check_mergetags(struct commit *commit, int argc, const char **argv)
373 {
374         struct check_mergetag_data mergetag_data;
375
376         mergetag_data.argc = argc;
377         mergetag_data.argv = argv;
378         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
379 }
380
381 static int create_graft(int argc, const char **argv, int force)
382 {
383         unsigned char old[20], new[20];
384         const char *old_ref = argv[0];
385         struct commit *commit;
386         struct strbuf buf = STRBUF_INIT;
387         const char *buffer;
388         unsigned long size;
389
390         if (get_sha1(old_ref, old) < 0)
391                 die(_("Not a valid object name: '%s'"), old_ref);
392         commit = lookup_commit_or_die(old, old_ref);
393
394         buffer = get_commit_buffer(commit, &size);
395         strbuf_add(&buf, buffer, size);
396         unuse_commit_buffer(commit, buffer);
397
398         replace_parents(&buf, argc - 1, &argv[1]);
399
400         if (remove_signature(&buf)) {
401                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
402                 warning(_("the signature will be removed in the replacement commit!"));
403         }
404
405         check_mergetags(commit, argc, argv);
406
407         if (write_sha1_file(buf.buf, buf.len, commit_type, new))
408                 die(_("could not write replacement commit for: '%s'"), old_ref);
409
410         strbuf_release(&buf);
411
412         if (!hashcmp(old, new))
413                 return error("new commit is the same as the old one: '%s'", sha1_to_hex(old));
414
415         return replace_object_sha1(old_ref, old, "replacement", new, force);
416 }
417
418 int cmd_replace(int argc, const char **argv, const char *prefix)
419 {
420         int force = 0;
421         int raw = 0;
422         const char *format = NULL;
423         enum {
424                 MODE_UNSPECIFIED = 0,
425                 MODE_LIST,
426                 MODE_DELETE,
427                 MODE_EDIT,
428                 MODE_GRAFT,
429                 MODE_REPLACE
430         } cmdmode = MODE_UNSPECIFIED;
431         struct option options[] = {
432                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
433                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
434                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
435                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
436                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
437                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
438                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
439                 OPT_END()
440         };
441
442         check_replace_refs = 0;
443
444         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
445
446         if (!cmdmode)
447                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
448
449         if (format && cmdmode != MODE_LIST)
450                 usage_msg_opt("--format cannot be used when not listing",
451                               git_replace_usage, options);
452
453         if (force &&
454             cmdmode != MODE_REPLACE &&
455             cmdmode != MODE_EDIT &&
456             cmdmode != MODE_GRAFT)
457                 usage_msg_opt("-f only makes sense when writing a replacement",
458                               git_replace_usage, options);
459
460         if (raw && cmdmode != MODE_EDIT)
461                 usage_msg_opt("--raw only makes sense with --edit",
462                               git_replace_usage, options);
463
464         switch (cmdmode) {
465         case MODE_DELETE:
466                 if (argc < 1)
467                         usage_msg_opt("-d needs at least one argument",
468                                       git_replace_usage, options);
469                 return for_each_replace_name(argv, delete_replace_ref);
470
471         case MODE_REPLACE:
472                 if (argc != 2)
473                         usage_msg_opt("bad number of arguments",
474                                       git_replace_usage, options);
475                 return replace_object(argv[0], argv[1], force);
476
477         case MODE_EDIT:
478                 if (argc != 1)
479                         usage_msg_opt("-e needs exactly one argument",
480                                       git_replace_usage, options);
481                 return edit_and_replace(argv[0], force, raw);
482
483         case MODE_GRAFT:
484                 if (argc < 1)
485                         usage_msg_opt("-g needs at least one argument",
486                                       git_replace_usage, options);
487                 return create_graft(argc, argv, force);
488
489         case MODE_LIST:
490                 if (argc > 1)
491                         usage_msg_opt("only one pattern can be given with -l",
492                                       git_replace_usage, options);
493                 return list_replace_refs(argv[0], format);
494
495         default:
496                 die("BUG: invalid cmdmode %d", (int)cmdmode);
497         }
498 }