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 "config.h"
  13 #include "builtin.h"
  14 #include "refs.h"
  15 #include "parse-options.h"
  16 #include "run-command.h"
  17 #include "object-store.h"
  18 #include "repository.h"
  19 #include "tag.h"
  20
  21 static const char * const git_replace_usage[] = {
  22         N_("git replace [-f] <object> <replacement>"),
  23         N_("git replace [-f] --edit <object>"),
  24         N_("git replace [-f] --graft <commit> [<parent>...]"),
  25         N_("git replace -d <object>..."),
  26         N_("git replace [--format=<format>] [-l [<pattern>]]"),
  27         NULL
  28 };
  29
  30 enum replace_format {
  31         REPLACE_FORMAT_SHORT,
  32         REPLACE_FORMAT_MEDIUM,
  33         REPLACE_FORMAT_LONG
  34 };
  35
  36 struct show_data {
  37         const char *pattern;
  38         enum replace_format format;
  39 };
  40
  41 static int show_reference(const char *refname, const struct object_id *oid,
  42                           int flag, void *cb_data)
  43 {
  44         struct show_data *data = cb_data;
  45
  46         if (!wildmatch(data->pattern, refname, 0)) {
  47                 if (data->format == REPLACE_FORMAT_SHORT)
  48                         printf("%s\n", refname);
  49                 else if (data->format == REPLACE_FORMAT_MEDIUM)
  50                         printf("%s -> %s\n", refname, oid_to_hex(oid));
  51                 else { /* data->format == REPLACE_FORMAT_LONG */
  52                         struct object_id object;
  53                         enum object_type obj_type, repl_type;
  54
  55                         if (get_oid(refname, &object))
  56                                 return error("Failed to resolve '%s' as a valid ref.", refname);
  57
  58                         obj_type = oid_object_info(the_repository, &object,
  59                                                    NULL);
  60                         repl_type = oid_object_info(the_repository, oid, NULL);
  61
  62                         printf("%s (%s) -> %s (%s)\n", refname, type_name(obj_type),
  63                                oid_to_hex(oid), type_name(repl_type));
  64                 }
  65         }
  66
  67         return 0;
  68 }
  69
  70 static int list_replace_refs(const char *pattern, const char *format)
  71 {
  72         struct show_data data;
  73
  74         if (pattern == NULL)
  75                 pattern = "*";
  76         data.pattern = pattern;
  77
  78         if (format == NULL || *format == '\0' || !strcmp(format, "short"))
  79                 data.format = REPLACE_FORMAT_SHORT;
  80         else if (!strcmp(format, "medium"))
  81                 data.format = REPLACE_FORMAT_MEDIUM;
  82         else if (!strcmp(format, "long"))
  83                 data.format = REPLACE_FORMAT_LONG;
  84         else
  85                 die("invalid replace format '%s'\n"
  86                     "valid formats are 'short', 'medium' and 'long'\n",
  87                     format);
  88
  89         for_each_replace_ref(the_repository, show_reference, (void *)&data);
  90
  91         return 0;
  92 }
  93
  94 typedef int (*each_replace_name_fn)(const char *name, const char *ref,
  95                                     const struct object_id *oid);
  96
  97 static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
  98 {
  99         const char **p, *full_hex;
 100         struct strbuf ref = STRBUF_INIT;
 101         size_t base_len;
 102         int had_error = 0;
 103         struct object_id oid;
 104
 105         strbuf_addstr(&ref, git_replace_ref_base);
 106         base_len = ref.len;
 107
 108         for (p = argv; *p; p++) {
 109                 if (get_oid(*p, &oid)) {
 110                         error("Failed to resolve '%s' as a valid ref.", *p);
 111                         had_error = 1;
 112                         continue;
 113                 }
 114
 115                 strbuf_setlen(&ref, base_len);
 116                 strbuf_addstr(&ref, oid_to_hex(&oid));
 117                 full_hex = ref.buf + base_len;
 118
 119                 if (read_ref(ref.buf, &oid)) {
 120                         error("replace ref '%s' not found.", full_hex);
 121                         had_error = 1;
 122                         continue;
 123                 }
 124                 if (fn(full_hex, ref.buf, &oid))
 125                         had_error = 1;
 126         }
 127         strbuf_release(&ref);
 128         return had_error;
 129 }
 130
 131 static int delete_replace_ref(const char *name, const char *ref,
 132                               const struct object_id *oid)
 133 {
 134         if (delete_ref(NULL, ref, oid, 0))
 135                 return 1;
 136         printf("Deleted replace ref '%s'\n", name);
 137         return 0;
 138 }
 139
 140 static void check_ref_valid(struct object_id *object,
 141                             struct object_id *prev,
 142                             struct strbuf *ref,
 143                             int force)
 144 {
 145         strbuf_reset(ref);
 146         strbuf_addf(ref, "%s%s", git_replace_ref_base, oid_to_hex(object));
 147         if (check_refname_format(ref->buf, 0))
 148                 die("'%s' is not a valid ref name.", ref->buf);
 149
 150         if (read_ref(ref->buf, prev))
 151                 oidclr(prev);
 152         else if (!force)
 153                 die("replace ref '%s' already exists", ref->buf);
 154 }
 155
 156 static int replace_object_oid(const char *object_ref,
 157                                struct object_id *object,
 158                                const char *replace_ref,
 159                                struct object_id *repl,
 160                                int force)
 161 {
 162         struct object_id prev;
 163         enum object_type obj_type, repl_type;
 164         struct strbuf ref = STRBUF_INIT;
 165         struct ref_transaction *transaction;
 166         struct strbuf err = STRBUF_INIT;
 167
 168         obj_type = oid_object_info(the_repository, object, NULL);
 169         repl_type = oid_object_info(the_repository, repl, NULL);
 170         if (!force && obj_type != repl_type)
 171                 die("Objects must be of the same type.\n"
 172                     "'%s' points to a replaced object of type '%s'\n"
 173                     "while '%s' points to a replacement object of type '%s'.",
 174                     object_ref, type_name(obj_type),
 175                     replace_ref, type_name(repl_type));
 176
 177         check_ref_valid(object, &prev, &ref, force);
 178
 179         transaction = ref_transaction_begin(&err);
 180         if (!transaction ||
 181             ref_transaction_update(transaction, ref.buf, repl, &prev,
 182                                    0, NULL, &err) ||
 183             ref_transaction_commit(transaction, &err))
 184                 die("%s", err.buf);
 185
 186         ref_transaction_free(transaction);
 187         strbuf_release(&ref);
 188         return 0;
 189 }
 190
 191 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 192 {
 193         struct object_id object, repl;
 194
 195         if (get_oid(object_ref, &object))
 196                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 197         if (get_oid(replace_ref, &repl))
 198                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 199
 200         return replace_object_oid(object_ref, &object, replace_ref, &repl, force);
 201 }
 202
 203 /*
 204  * Write the contents of the object named by "sha1" to the file "filename".
 205  * If "raw" is true, then the object's raw contents are printed according to
 206  * "type". Otherwise, we pretty-print the contents for human editing.
 207  */
 208 static void export_object(const struct object_id *oid, enum object_type type,
 209                           int raw, const char *filename)
 210 {
 211         struct child_process cmd = CHILD_PROCESS_INIT;
 212         int fd;
 213
 214         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 215         if (fd < 0)
 216                 die_errno("unable to open %s for writing", filename);
 217
 218         argv_array_push(&cmd.args, "--no-replace-objects");
 219         argv_array_push(&cmd.args, "cat-file");
 220         if (raw)
 221                 argv_array_push(&cmd.args, type_name(type));
 222         else
 223                 argv_array_push(&cmd.args, "-p");
 224         argv_array_push(&cmd.args, oid_to_hex(oid));
 225         cmd.git_cmd = 1;
 226         cmd.out = fd;
 227
 228         if (run_command(&cmd))
 229                 die("cat-file reported failure");
 230 }
 231
 232 /*
 233  * Read a previously-exported (and possibly edited) object back from "filename",
 234  * interpreting it as "type", and writing the result to the object database.
 235  * The sha1 of the written object is returned via sha1.
 236  */
 237 static void import_object(struct object_id *oid, enum object_type type,
 238                           int raw, const char *filename)
 239 {
 240         int fd;
 241
 242         fd = open(filename, O_RDONLY);
 243         if (fd < 0)
 244                 die_errno("unable to open %s for reading", filename);
 245
 246         if (!raw && type == OBJ_TREE) {
 247                 const char *argv[] = { "mktree", NULL };
 248                 struct child_process cmd = CHILD_PROCESS_INIT;
 249                 struct strbuf result = STRBUF_INIT;
 250
 251                 cmd.argv = argv;
 252                 cmd.git_cmd = 1;
 253                 cmd.in = fd;
 254                 cmd.out = -1;
 255
 256                 if (start_command(&cmd))
 257                         die("unable to spawn mktree");
 258
 259                 if (strbuf_read(&result, cmd.out, 41) < 0)
 260                         die_errno("unable to read from mktree");
 261                 close(cmd.out);
 262
 263                 if (finish_command(&cmd))
 264                         die("mktree reported failure");
 265                 if (get_oid_hex(result.buf, oid) < 0)
 266                         die("mktree did not return an object name");
 267
 268                 strbuf_release(&result);
 269         } else {
 270                 struct stat st;
 271                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 272
 273                 if (fstat(fd, &st) < 0)
 274                         die_errno("unable to fstat %s", filename);
 275                 if (index_fd(oid, fd, &st, type, NULL, flags) < 0)
 276                         die("unable to write object to database");
 277                 /* index_fd close()s fd for us */
 278         }
 279
 280         /*
 281          * No need to close(fd) here; both run-command and index-fd
 282          * will have done it for us.
 283          */
 284 }
 285
 286 static int edit_and_replace(const char *object_ref, int force, int raw)
 287 {
 288         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 289         enum object_type type;
 290         struct object_id old_oid, new_oid, prev;
 291         struct strbuf ref = STRBUF_INIT;
 292
 293         if (get_oid(object_ref, &old_oid) < 0)
 294                 die("Not a valid object name: '%s'", object_ref);
 295
 296         type = oid_object_info(the_repository, &old_oid, NULL);
 297         if (type < 0)
 298                 die("unable to get object type for %s", oid_to_hex(&old_oid));
 299
 300         check_ref_valid(&old_oid, &prev, &ref, force);
 301         strbuf_release(&ref);
 302
 303         export_object(&old_oid, type, raw, tmpfile);
 304         if (launch_editor(tmpfile, NULL, NULL) < 0)
 305                 die("editing object file failed");
 306         import_object(&new_oid, type, raw, tmpfile);
 307
 308         free(tmpfile);
 309
 310         if (!oidcmp(&old_oid, &new_oid))
 311                 return error("new object is the same as the old one: '%s'", oid_to_hex(&old_oid));
 312
 313         return replace_object_oid(object_ref, &old_oid, "replacement", &new_oid, force);
 314 }
 315
 316 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 317 {
 318         struct strbuf new_parents = STRBUF_INIT;
 319         const char *parent_start, *parent_end;
 320         int i;
 321
 322         /* find existing parents */
 323         parent_start = buf->buf;
 324         parent_start += GIT_SHA1_HEXSZ + 6; /* "tree " + "hex sha1" + "\n" */
 325         parent_end = parent_start;
 326
 327         while (starts_with(parent_end, "parent "))
 328                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 329
 330         /* prepare new parents */
 331         for (i = 0; i < argc; i++) {
 332                 struct object_id oid;
 333                 if (get_oid(argv[i], &oid) < 0)
 334                         die(_("Not a valid object name: '%s'"), argv[i]);
 335                 lookup_commit_or_die(&oid, argv[i]);
 336                 strbuf_addf(&new_parents, "parent %s\n", oid_to_hex(&oid));
 337         }
 338
 339         /* replace existing parents with new ones */
 340         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 341                       new_parents.buf, new_parents.len);
 342
 343         strbuf_release(&new_parents);
 344 }
 345
 346 struct check_mergetag_data {
 347         int argc;
 348         const char **argv;
 349 };
 350
 351 static void check_one_mergetag(struct commit *commit,
 352                                struct commit_extra_header *extra,
 353                                void *data)
 354 {
 355         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
 356         const char *ref = mergetag_data->argv[0];
 357         struct object_id tag_oid;
 358         struct tag *tag;
 359         int i;
 360
 361         hash_object_file(extra->value, extra->len, type_name(OBJ_TAG), &tag_oid);
 362         tag = lookup_tag(&tag_oid);
 363         if (!tag)
 364                 die(_("bad mergetag in commit '%s'"), ref);
 365         if (parse_tag_buffer(tag, extra->value, extra->len))
 366                 die(_("malformed mergetag in commit '%s'"), ref);
 367
 368         /* iterate over new parents */
 369         for (i = 1; i < mergetag_data->argc; i++) {
 370                 struct object_id oid;
 371                 if (get_oid(mergetag_data->argv[i], &oid) < 0)
 372                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 373                 if (!oidcmp(&tag->tagged->oid, &oid))
 374                         return; /* found */
 375         }
 376
 377         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
 378               "use --edit instead of --graft"), ref, oid_to_hex(&tag_oid));
 379 }
 380
 381 static void check_mergetags(struct commit *commit, int argc, const char **argv)
 382 {
 383         struct check_mergetag_data mergetag_data;
 384
 385         mergetag_data.argc = argc;
 386         mergetag_data.argv = argv;
 387         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
 388 }
 389
 390 static int create_graft(int argc, const char **argv, int force)
 391 {
 392         struct object_id old_oid, new_oid;
 393         const char *old_ref = argv[0];
 394         struct commit *commit;
 395         struct strbuf buf = STRBUF_INIT;
 396         const char *buffer;
 397         unsigned long size;
 398
 399         if (get_oid(old_ref, &old_oid) < 0)
 400                 die(_("Not a valid object name: '%s'"), old_ref);
 401         commit = lookup_commit_or_die(&old_oid, old_ref);
 402
 403         buffer = get_commit_buffer(commit, &size);
 404         strbuf_add(&buf, buffer, size);
 405         unuse_commit_buffer(commit, buffer);
 406
 407         replace_parents(&buf, argc - 1, &argv[1]);
 408
 409         if (remove_signature(&buf)) {
 410                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 411                 warning(_("the signature will be removed in the replacement commit!"));
 412         }
 413
 414         check_mergetags(commit, argc, argv);
 415
 416         if (write_object_file(buf.buf, buf.len, commit_type, &new_oid))
 417                 die(_("could not write replacement commit for: '%s'"), old_ref);
 418
 419         strbuf_release(&buf);
 420
 421         if (!oidcmp(&old_oid, &new_oid))
 422                 return error("new commit is the same as the old one: '%s'", oid_to_hex(&old_oid));
 423
 424         return replace_object_oid(old_ref, &old_oid, "replacement", &new_oid, force);
 425 }
 426
 427 int cmd_replace(int argc, const char **argv, const char *prefix)
 428 {
 429         int force = 0;
 430         int raw = 0;
 431         const char *format = NULL;
 432         enum {
 433                 MODE_UNSPECIFIED = 0,
 434                 MODE_LIST,
 435                 MODE_DELETE,
 436                 MODE_EDIT,
 437                 MODE_GRAFT,
 438                 MODE_REPLACE
 439         } cmdmode = MODE_UNSPECIFIED;
 440         struct option options[] = {
 441                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 442                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 443                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 444                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 445                 OPT_BOOL_F('f', "force", &force, N_("replace the ref if it exists"),
 446                            PARSE_OPT_NOCOMPLETE),
 447                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 448                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 449                 OPT_END()
 450         };
 451
 452         check_replace_refs = 0;
 453         git_config(git_default_config, NULL);
 454
 455         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 456
 457         if (!cmdmode)
 458                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 459
 460         if (format && cmdmode != MODE_LIST)
 461                 usage_msg_opt("--format cannot be used when not listing",
 462                               git_replace_usage, options);
 463
 464         if (force &&
 465             cmdmode != MODE_REPLACE &&
 466             cmdmode != MODE_EDIT &&
 467             cmdmode != MODE_GRAFT)
 468                 usage_msg_opt("-f only makes sense when writing a replacement",
 469                               git_replace_usage, options);
 470
 471         if (raw && cmdmode != MODE_EDIT)
 472                 usage_msg_opt("--raw only makes sense with --edit",
 473                               git_replace_usage, options);
 474
 475         switch (cmdmode) {
 476         case MODE_DELETE:
 477                 if (argc < 1)
 478                         usage_msg_opt("-d needs at least one argument",
 479                                       git_replace_usage, options);
 480                 return for_each_replace_name(argv, delete_replace_ref);
 481
 482         case MODE_REPLACE:
 483                 if (argc != 2)
 484                         usage_msg_opt("bad number of arguments",
 485                                       git_replace_usage, options);
 486                 return replace_object(argv[0], argv[1], force);
 487
 488         case MODE_EDIT:
 489                 if (argc != 1)
 490                         usage_msg_opt("-e needs exactly one argument",
 491                                       git_replace_usage, options);
 492                 return edit_and_replace(argv[0], force, raw);
 493
 494         case MODE_GRAFT:
 495                 if (argc < 1)
 496                         usage_msg_opt("-g needs at least one argument",
 497                                       git_replace_usage, options);
 498                 return create_graft(argc, argv, force);
 499
 500         case MODE_LIST:
 501                 if (argc > 1)
 502                         usage_msg_opt("only one pattern can be given with -l",
 503                                       git_replace_usage, options);
 504                 return list_replace_refs(argv[0], format);
 505
 506         default:
 507                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 508         }
 509 }