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 "tag.h"
  18
  19 static const char * const git_replace_usage[] = {
  20         N_("git replace [-f] <object> <replacement>"),
  21         N_("git replace [-f] --edit <object>"),
  22         N_("git replace [-f] --graft <commit> [<parent>...]"),
  23         N_("git replace -d <object>..."),
  24         N_("git replace [--format=<format>] [-l [<pattern>]]"),
  25         NULL
  26 };
  27
  28 enum replace_format {
  29         REPLACE_FORMAT_SHORT,
  30         REPLACE_FORMAT_MEDIUM,
  31         REPLACE_FORMAT_LONG
  32 };
  33
  34 struct show_data {
  35         const char *pattern;
  36         enum replace_format format;
  37 };
  38
  39 static int show_reference(const char *refname, const struct object_id *oid,
  40                           int flag, void *cb_data)
  41 {
  42         struct show_data *data = cb_data;
  43
  44         if (!wildmatch(data->pattern, refname, 0)) {
  45                 if (data->format == REPLACE_FORMAT_SHORT)
  46                         printf("%s\n", refname);
  47                 else if (data->format == REPLACE_FORMAT_MEDIUM)
  48                         printf("%s -> %s\n", refname, oid_to_hex(oid));
  49                 else { /* data->format == REPLACE_FORMAT_LONG */
  50                         struct object_id object;
  51                         enum object_type obj_type, repl_type;
  52
  53                         if (get_oid(refname, &object))
  54                                 return error("Failed to resolve '%s' as a valid ref.", refname);
  55
  56                         obj_type = sha1_object_info(object.hash, NULL);
  57                         repl_type = sha1_object_info(oid->hash, NULL);
  58
  59                         printf("%s (%s) -> %s (%s)\n", refname, typename(obj_type),
  60                                oid_to_hex(oid), typename(repl_type));
  61                 }
  62         }
  63
  64         return 0;
  65 }
  66
  67 static int list_replace_refs(const char *pattern, const char *format)
  68 {
  69         struct show_data data;
  70
  71         if (pattern == NULL)
  72                 pattern = "*";
  73         data.pattern = pattern;
  74
  75         if (format == NULL || *format == '\0' || !strcmp(format, "short"))
  76                 data.format = REPLACE_FORMAT_SHORT;
  77         else if (!strcmp(format, "medium"))
  78                 data.format = REPLACE_FORMAT_MEDIUM;
  79         else if (!strcmp(format, "long"))
  80                 data.format = REPLACE_FORMAT_LONG;
  81         else
  82                 die("invalid replace format '%s'\n"
  83                     "valid formats are 'short', 'medium' and 'long'\n",
  84                     format);
  85
  86         for_each_replace_ref(show_reference, (void *)&data);
  87
  88         return 0;
  89 }
  90
  91 typedef int (*each_replace_name_fn)(const char *name, const char *ref,
  92                                     const struct object_id *oid);
  93
  94 static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
  95 {
  96         const char **p, *full_hex;
  97         struct strbuf ref = STRBUF_INIT;
  98         size_t base_len;
  99         int had_error = 0;
 100         struct object_id oid;
 101
 102         strbuf_addstr(&ref, git_replace_ref_base);
 103         base_len = ref.len;
 104
 105         for (p = argv; *p; p++) {
 106                 if (get_oid(*p, &oid)) {
 107                         error("Failed to resolve '%s' as a valid ref.", *p);
 108                         had_error = 1;
 109                         continue;
 110                 }
 111
 112                 strbuf_setlen(&ref, base_len);
 113                 strbuf_addstr(&ref, oid_to_hex(&oid));
 114                 full_hex = ref.buf + base_len;
 115
 116                 if (read_ref(ref.buf, oid.hash)) {
 117                         error("replace ref '%s' not found.", full_hex);
 118                         had_error = 1;
 119                         continue;
 120                 }
 121                 if (fn(full_hex, ref.buf, &oid))
 122                         had_error = 1;
 123         }
 124         strbuf_release(&ref);
 125         return had_error;
 126 }
 127
 128 static int delete_replace_ref(const char *name, const char *ref,
 129                               const struct object_id *oid)
 130 {
 131         if (delete_ref(NULL, ref, oid->hash, 0))
 132                 return 1;
 133         printf("Deleted replace ref '%s'\n", name);
 134         return 0;
 135 }
 136
 137 static void check_ref_valid(struct object_id *object,
 138                             struct object_id *prev,
 139                             struct strbuf *ref,
 140                             int force)
 141 {
 142         strbuf_reset(ref);
 143         strbuf_addf(ref, "%s%s", git_replace_ref_base, oid_to_hex(object));
 144         if (check_refname_format(ref->buf, 0))
 145                 die("'%s' is not a valid ref name.", ref->buf);
 146
 147         if (read_ref(ref->buf, prev->hash))
 148                 oidclr(prev);
 149         else if (!force)
 150                 die("replace ref '%s' already exists", ref->buf);
 151 }
 152
 153 static int replace_object_oid(const char *object_ref,
 154                                struct object_id *object,
 155                                const char *replace_ref,
 156                                struct object_id *repl,
 157                                int force)
 158 {
 159         struct object_id prev;
 160         enum object_type obj_type, repl_type;
 161         struct strbuf ref = STRBUF_INIT;
 162         struct ref_transaction *transaction;
 163         struct strbuf err = STRBUF_INIT;
 164
 165         obj_type = sha1_object_info(object->hash, NULL);
 166         repl_type = sha1_object_info(repl->hash, NULL);
 167         if (!force && obj_type != repl_type)
 168                 die("Objects must be of the same type.\n"
 169                     "'%s' points to a replaced object of type '%s'\n"
 170                     "while '%s' points to a replacement object of type '%s'.",
 171                     object_ref, typename(obj_type),
 172                     replace_ref, typename(repl_type));
 173
 174         check_ref_valid(object, &prev, &ref, force);
 175
 176         transaction = ref_transaction_begin(&err);
 177         if (!transaction ||
 178             ref_transaction_update(transaction, ref.buf, repl->hash, prev.hash,
 179                                    0, NULL, &err) ||
 180             ref_transaction_commit(transaction, &err))
 181                 die("%s", err.buf);
 182
 183         ref_transaction_free(transaction);
 184         strbuf_release(&ref);
 185         return 0;
 186 }
 187
 188 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 189 {
 190         struct object_id object, repl;
 191
 192         if (get_oid(object_ref, &object))
 193                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 194         if (get_oid(replace_ref, &repl))
 195                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 196
 197         return replace_object_oid(object_ref, &object, replace_ref, &repl, force);
 198 }
 199
 200 /*
 201  * Write the contents of the object named by "sha1" to the file "filename".
 202  * If "raw" is true, then the object's raw contents are printed according to
 203  * "type". Otherwise, we pretty-print the contents for human editing.
 204  */
 205 static void export_object(const struct object_id *oid, enum object_type type,
 206                           int raw, const char *filename)
 207 {
 208         struct child_process cmd = CHILD_PROCESS_INIT;
 209         int fd;
 210
 211         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 212         if (fd < 0)
 213                 die_errno("unable to open %s for writing", filename);
 214
 215         argv_array_push(&cmd.args, "--no-replace-objects");
 216         argv_array_push(&cmd.args, "cat-file");
 217         if (raw)
 218                 argv_array_push(&cmd.args, typename(type));
 219         else
 220                 argv_array_push(&cmd.args, "-p");
 221         argv_array_push(&cmd.args, oid_to_hex(oid));
 222         cmd.git_cmd = 1;
 223         cmd.out = fd;
 224
 225         if (run_command(&cmd))
 226                 die("cat-file reported failure");
 227 }
 228
 229 /*
 230  * Read a previously-exported (and possibly edited) object back from "filename",
 231  * interpreting it as "type", and writing the result to the object database.
 232  * The sha1 of the written object is returned via sha1.
 233  */
 234 static void import_object(struct object_id *oid, enum object_type type,
 235                           int raw, const char *filename)
 236 {
 237         int fd;
 238
 239         fd = open(filename, O_RDONLY);
 240         if (fd < 0)
 241                 die_errno("unable to open %s for reading", filename);
 242
 243         if (!raw && type == OBJ_TREE) {
 244                 const char *argv[] = { "mktree", NULL };
 245                 struct child_process cmd = CHILD_PROCESS_INIT;
 246                 struct strbuf result = STRBUF_INIT;
 247
 248                 cmd.argv = argv;
 249                 cmd.git_cmd = 1;
 250                 cmd.in = fd;
 251                 cmd.out = -1;
 252
 253                 if (start_command(&cmd))
 254                         die("unable to spawn mktree");
 255
 256                 if (strbuf_read(&result, cmd.out, 41) < 0)
 257                         die_errno("unable to read from mktree");
 258                 close(cmd.out);
 259
 260                 if (finish_command(&cmd))
 261                         die("mktree reported failure");
 262                 if (get_oid_hex(result.buf, oid) < 0)
 263                         die("mktree did not return an object name");
 264
 265                 strbuf_release(&result);
 266         } else {
 267                 struct stat st;
 268                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 269
 270                 if (fstat(fd, &st) < 0)
 271                         die_errno("unable to fstat %s", filename);
 272                 if (index_fd(oid, fd, &st, type, NULL, flags) < 0)
 273                         die("unable to write object to database");
 274                 /* index_fd close()s fd for us */
 275         }
 276
 277         /*
 278          * No need to close(fd) here; both run-command and index-fd
 279          * will have done it for us.
 280          */
 281 }
 282
 283 static int edit_and_replace(const char *object_ref, int force, int raw)
 284 {
 285         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 286         enum object_type type;
 287         struct object_id old, new, prev;
 288         struct strbuf ref = STRBUF_INIT;
 289
 290         if (get_oid(object_ref, &old) < 0)
 291                 die("Not a valid object name: '%s'", object_ref);
 292
 293         type = sha1_object_info(old.hash, NULL);
 294         if (type < 0)
 295                 die("unable to get object type for %s", oid_to_hex(&old));
 296
 297         check_ref_valid(&old, &prev, &ref, force);
 298         strbuf_release(&ref);
 299
 300         export_object(&old, type, raw, tmpfile);
 301         if (launch_editor(tmpfile, NULL, NULL) < 0)
 302                 die("editing object file failed");
 303         import_object(&new, type, raw, tmpfile);
 304
 305         free(tmpfile);
 306
 307         if (!oidcmp(&old, &new))
 308                 return error("new object is the same as the old one: '%s'", oid_to_hex(&old));
 309
 310         return replace_object_oid(object_ref, &old, "replacement", &new, force);
 311 }
 312
 313 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 314 {
 315         struct strbuf new_parents = STRBUF_INIT;
 316         const char *parent_start, *parent_end;
 317         int i;
 318
 319         /* find existing parents */
 320         parent_start = buf->buf;
 321         parent_start += GIT_SHA1_HEXSZ + 6; /* "tree " + "hex sha1" + "\n" */
 322         parent_end = parent_start;
 323
 324         while (starts_with(parent_end, "parent "))
 325                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 326
 327         /* prepare new parents */
 328         for (i = 0; i < argc; i++) {
 329                 struct object_id oid;
 330                 if (get_oid(argv[i], &oid) < 0)
 331                         die(_("Not a valid object name: '%s'"), argv[i]);
 332                 lookup_commit_or_die(&oid, argv[i]);
 333                 strbuf_addf(&new_parents, "parent %s\n", oid_to_hex(&oid));
 334         }
 335
 336         /* replace existing parents with new ones */
 337         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 338                       new_parents.buf, new_parents.len);
 339
 340         strbuf_release(&new_parents);
 341 }
 342
 343 struct check_mergetag_data {
 344         int argc;
 345         const char **argv;
 346 };
 347
 348 static void check_one_mergetag(struct commit *commit,
 349                                struct commit_extra_header *extra,
 350                                void *data)
 351 {
 352         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
 353         const char *ref = mergetag_data->argv[0];
 354         struct object_id tag_oid;
 355         struct tag *tag;
 356         int i;
 357
 358         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_oid.hash);
 359         tag = lookup_tag(&tag_oid);
 360         if (!tag)
 361                 die(_("bad mergetag in commit '%s'"), ref);
 362         if (parse_tag_buffer(tag, extra->value, extra->len))
 363                 die(_("malformed mergetag in commit '%s'"), ref);
 364
 365         /* iterate over new parents */
 366         for (i = 1; i < mergetag_data->argc; i++) {
 367                 struct object_id oid;
 368                 if (get_oid(mergetag_data->argv[i], &oid) < 0)
 369                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 370                 if (!oidcmp(&tag->tagged->oid, &oid))
 371                         return; /* found */
 372         }
 373
 374         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
 375               "use --edit instead of --graft"), ref, oid_to_hex(&tag_oid));
 376 }
 377
 378 static void check_mergetags(struct commit *commit, int argc, const char **argv)
 379 {
 380         struct check_mergetag_data mergetag_data;
 381
 382         mergetag_data.argc = argc;
 383         mergetag_data.argv = argv;
 384         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
 385 }
 386
 387 static int create_graft(int argc, const char **argv, int force)
 388 {
 389         struct object_id old, new;
 390         const char *old_ref = argv[0];
 391         struct commit *commit;
 392         struct strbuf buf = STRBUF_INIT;
 393         const char *buffer;
 394         unsigned long size;
 395
 396         if (get_oid(old_ref, &old) < 0)
 397                 die(_("Not a valid object name: '%s'"), old_ref);
 398         commit = lookup_commit_or_die(&old, old_ref);
 399
 400         buffer = get_commit_buffer(commit, &size);
 401         strbuf_add(&buf, buffer, size);
 402         unuse_commit_buffer(commit, buffer);
 403
 404         replace_parents(&buf, argc - 1, &argv[1]);
 405
 406         if (remove_signature(&buf)) {
 407                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 408                 warning(_("the signature will be removed in the replacement commit!"));
 409         }
 410
 411         check_mergetags(commit, argc, argv);
 412
 413         if (write_sha1_file(buf.buf, buf.len, commit_type, new.hash))
 414                 die(_("could not write replacement commit for: '%s'"), old_ref);
 415
 416         strbuf_release(&buf);
 417
 418         if (!oidcmp(&old, &new))
 419                 return error("new commit is the same as the old one: '%s'", oid_to_hex(&old));
 420
 421         return replace_object_oid(old_ref, &old, "replacement", &new, force);
 422 }
 423
 424 int cmd_replace(int argc, const char **argv, const char *prefix)
 425 {
 426         int force = 0;
 427         int raw = 0;
 428         const char *format = NULL;
 429         enum {
 430                 MODE_UNSPECIFIED = 0,
 431                 MODE_LIST,
 432                 MODE_DELETE,
 433                 MODE_EDIT,
 434                 MODE_GRAFT,
 435                 MODE_REPLACE
 436         } cmdmode = MODE_UNSPECIFIED;
 437         struct option options[] = {
 438                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 439                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 440                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 441                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 442                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
 443                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 444                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 445                 OPT_END()
 446         };
 447
 448         check_replace_refs = 0;
 449         git_config(git_default_config, NULL);
 450
 451         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 452
 453         if (!cmdmode)
 454                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 455
 456         if (format && cmdmode != MODE_LIST)
 457                 usage_msg_opt("--format cannot be used when not listing",
 458                               git_replace_usage, options);
 459
 460         if (force &&
 461             cmdmode != MODE_REPLACE &&
 462             cmdmode != MODE_EDIT &&
 463             cmdmode != MODE_GRAFT)
 464                 usage_msg_opt("-f only makes sense when writing a replacement",
 465                               git_replace_usage, options);
 466
 467         if (raw && cmdmode != MODE_EDIT)
 468                 usage_msg_opt("--raw only makes sense with --edit",
 469                               git_replace_usage, options);
 470
 471         switch (cmdmode) {
 472         case MODE_DELETE:
 473                 if (argc < 1)
 474                         usage_msg_opt("-d needs at least one argument",
 475                                       git_replace_usage, options);
 476                 return for_each_replace_name(argv, delete_replace_ref);
 477
 478         case MODE_REPLACE:
 479                 if (argc != 2)
 480                         usage_msg_opt("bad number of arguments",
 481                                       git_replace_usage, options);
 482                 return replace_object(argv[0], argv[1], force);
 483
 484         case MODE_EDIT:
 485                 if (argc != 1)
 486                         usage_msg_opt("-e needs exactly one argument",
 487                                       git_replace_usage, options);
 488                 return edit_and_replace(argv[0], force, raw);
 489
 490         case MODE_GRAFT:
 491                 if (argc < 1)
 492                         usage_msg_opt("-g needs at least one argument",
 493                                       git_replace_usage, options);
 494                 return create_graft(argc, argv, force);
 495
 496         case MODE_LIST:
 497                 if (argc > 1)
 498                         usage_msg_opt("only one pattern can be given with -l",
 499                                       git_replace_usage, options);
 500                 return list_replace_refs(argv[0], format);
 501
 502         default:
 503                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 504         }
 505 }