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