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         return had_error;
 124 }
 125
 126 static int delete_replace_ref(const char *name, const char *ref,
 127                               const struct object_id *oid)
 128 {
 129         if (delete_ref(NULL, ref, oid->hash, 0))
 130                 return 1;
 131         printf("Deleted replace ref '%s'\n", name);
 132         return 0;
 133 }
 134
 135 static void check_ref_valid(struct object_id *object,
 136                             struct object_id *prev,
 137                             struct strbuf *ref,
 138                             int force)
 139 {
 140         strbuf_reset(ref);
 141         strbuf_addf(ref, "%s%s", git_replace_ref_base, oid_to_hex(object));
 142         if (check_refname_format(ref->buf, 0))
 143                 die("'%s' is not a valid ref name.", ref->buf);
 144
 145         if (read_ref(ref->buf, prev->hash))
 146                 oidclr(prev);
 147         else if (!force)
 148                 die("replace ref '%s' already exists", ref->buf);
 149 }
 150
 151 static int replace_object_oid(const char *object_ref,
 152                                struct object_id *object,
 153                                const char *replace_ref,
 154                                struct object_id *repl,
 155                                int force)
 156 {
 157         struct object_id prev;
 158         enum object_type obj_type, repl_type;
 159         struct strbuf ref = STRBUF_INIT;
 160         struct ref_transaction *transaction;
 161         struct strbuf err = STRBUF_INIT;
 162
 163         obj_type = sha1_object_info(object->hash, NULL);
 164         repl_type = sha1_object_info(repl->hash, NULL);
 165         if (!force && obj_type != repl_type)
 166                 die("Objects must be of the same type.\n"
 167                     "'%s' points to a replaced object of type '%s'\n"
 168                     "while '%s' points to a replacement object of type '%s'.",
 169                     object_ref, typename(obj_type),
 170                     replace_ref, typename(repl_type));
 171
 172         check_ref_valid(object, &prev, &ref, force);
 173
 174         transaction = ref_transaction_begin(&err);
 175         if (!transaction ||
 176             ref_transaction_update(transaction, ref.buf, repl->hash, prev.hash,
 177                                    0, NULL, &err) ||
 178             ref_transaction_commit(transaction, &err))
 179                 die("%s", err.buf);
 180
 181         ref_transaction_free(transaction);
 182         strbuf_release(&ref);
 183         return 0;
 184 }
 185
 186 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 187 {
 188         struct object_id object, repl;
 189
 190         if (get_oid(object_ref, &object))
 191                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 192         if (get_oid(replace_ref, &repl))
 193                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 194
 195         return replace_object_oid(object_ref, &object, replace_ref, &repl, force);
 196 }
 197
 198 /*
 199  * Write the contents of the object named by "sha1" to the file "filename".
 200  * If "raw" is true, then the object's raw contents are printed according to
 201  * "type". Otherwise, we pretty-print the contents for human editing.
 202  */
 203 static void export_object(const struct object_id *oid, enum object_type type,
 204                           int raw, const char *filename)
 205 {
 206         struct child_process cmd = CHILD_PROCESS_INIT;
 207         int fd;
 208
 209         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 210         if (fd < 0)
 211                 die_errno("unable to open %s for writing", filename);
 212
 213         argv_array_push(&cmd.args, "--no-replace-objects");
 214         argv_array_push(&cmd.args, "cat-file");
 215         if (raw)
 216                 argv_array_push(&cmd.args, typename(type));
 217         else
 218                 argv_array_push(&cmd.args, "-p");
 219         argv_array_push(&cmd.args, oid_to_hex(oid));
 220         cmd.git_cmd = 1;
 221         cmd.out = fd;
 222
 223         if (run_command(&cmd))
 224                 die("cat-file reported failure");
 225 }
 226
 227 /*
 228  * Read a previously-exported (and possibly edited) object back from "filename",
 229  * interpreting it as "type", and writing the result to the object database.
 230  * The sha1 of the written object is returned via sha1.
 231  */
 232 static void import_object(struct object_id *oid, enum object_type type,
 233                           int raw, const char *filename)
 234 {
 235         int fd;
 236
 237         fd = open(filename, O_RDONLY);
 238         if (fd < 0)
 239                 die_errno("unable to open %s for reading", filename);
 240
 241         if (!raw && type == OBJ_TREE) {
 242                 const char *argv[] = { "mktree", NULL };
 243                 struct child_process cmd = CHILD_PROCESS_INIT;
 244                 struct strbuf result = STRBUF_INIT;
 245
 246                 cmd.argv = argv;
 247                 cmd.git_cmd = 1;
 248                 cmd.in = fd;
 249                 cmd.out = -1;
 250
 251                 if (start_command(&cmd))
 252                         die("unable to spawn mktree");
 253
 254                 if (strbuf_read(&result, cmd.out, 41) < 0)
 255                         die_errno("unable to read from mktree");
 256                 close(cmd.out);
 257
 258                 if (finish_command(&cmd))
 259                         die("mktree reported failure");
 260                 if (get_oid_hex(result.buf, oid) < 0)
 261                         die("mktree did not return an object name");
 262
 263                 strbuf_release(&result);
 264         } else {
 265                 struct stat st;
 266                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 267
 268                 if (fstat(fd, &st) < 0)
 269                         die_errno("unable to fstat %s", filename);
 270                 if (index_fd(oid->hash, fd, &st, type, NULL, flags) < 0)
 271                         die("unable to write object to database");
 272                 /* index_fd close()s fd for us */
 273         }
 274
 275         /*
 276          * No need to close(fd) here; both run-command and index-fd
 277          * will have done it for us.
 278          */
 279 }
 280
 281 static int edit_and_replace(const char *object_ref, int force, int raw)
 282 {
 283         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 284         enum object_type type;
 285         struct object_id old, new, prev;
 286         struct strbuf ref = STRBUF_INIT;
 287
 288         if (get_oid(object_ref, &old) < 0)
 289                 die("Not a valid object name: '%s'", object_ref);
 290
 291         type = sha1_object_info(old.hash, NULL);
 292         if (type < 0)
 293                 die("unable to get object type for %s", oid_to_hex(&old));
 294
 295         check_ref_valid(&old, &prev, &ref, force);
 296         strbuf_release(&ref);
 297
 298         export_object(&old, type, raw, tmpfile);
 299         if (launch_editor(tmpfile, NULL, NULL) < 0)
 300                 die("editing object file failed");
 301         import_object(&new, type, raw, tmpfile);
 302
 303         free(tmpfile);
 304
 305         if (!oidcmp(&old, &new))
 306                 return error("new object is the same as the old one: '%s'", oid_to_hex(&old));
 307
 308         return replace_object_oid(object_ref, &old, "replacement", &new, force);
 309 }
 310
 311 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 312 {
 313         struct strbuf new_parents = STRBUF_INIT;
 314         const char *parent_start, *parent_end;
 315         int i;
 316
 317         /* find existing parents */
 318         parent_start = buf->buf;
 319         parent_start += GIT_SHA1_HEXSZ + 6; /* "tree " + "hex sha1" + "\n" */
 320         parent_end = parent_start;
 321
 322         while (starts_with(parent_end, "parent "))
 323                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 324
 325         /* prepare new parents */
 326         for (i = 0; i < argc; i++) {
 327                 struct object_id oid;
 328                 if (get_oid(argv[i], &oid) < 0)
 329                         die(_("Not a valid object name: '%s'"), argv[i]);
 330                 lookup_commit_or_die(oid.hash, argv[i]);
 331                 strbuf_addf(&new_parents, "parent %s\n", oid_to_hex(&oid));
 332         }
 333
 334         /* replace existing parents with new ones */
 335         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 336                       new_parents.buf, new_parents.len);
 337
 338         strbuf_release(&new_parents);
 339 }
 340
 341 struct check_mergetag_data {
 342         int argc;
 343         const char **argv;
 344 };
 345
 346 static void check_one_mergetag(struct commit *commit,
 347                                struct commit_extra_header *extra,
 348                                void *data)
 349 {
 350         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
 351         const char *ref = mergetag_data->argv[0];
 352         struct object_id tag_oid;
 353         struct tag *tag;
 354         int i;
 355
 356         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_oid.hash);
 357         tag = lookup_tag(tag_oid.hash);
 358         if (!tag)
 359                 die(_("bad mergetag in commit '%s'"), ref);
 360         if (parse_tag_buffer(tag, extra->value, extra->len))
 361                 die(_("malformed mergetag in commit '%s'"), ref);
 362
 363         /* iterate over new parents */
 364         for (i = 1; i < mergetag_data->argc; i++) {
 365                 struct object_id oid;
 366                 if (get_sha1(mergetag_data->argv[i], oid.hash) < 0)
 367                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 368                 if (!oidcmp(&tag->tagged->oid, &oid))
 369                         return; /* found */
 370         }
 371
 372         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
 373               "use --edit instead of --graft"), ref, oid_to_hex(&tag_oid));
 374 }
 375
 376 static void check_mergetags(struct commit *commit, int argc, const char **argv)
 377 {
 378         struct check_mergetag_data mergetag_data;
 379
 380         mergetag_data.argc = argc;
 381         mergetag_data.argv = argv;
 382         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
 383 }
 384
 385 static int create_graft(int argc, const char **argv, int force)
 386 {
 387         struct object_id old, new;
 388         const char *old_ref = argv[0];
 389         struct commit *commit;
 390         struct strbuf buf = STRBUF_INIT;
 391         const char *buffer;
 392         unsigned long size;
 393
 394         if (get_oid(old_ref, &old) < 0)
 395                 die(_("Not a valid object name: '%s'"), old_ref);
 396         commit = lookup_commit_or_die(old.hash, old_ref);
 397
 398         buffer = get_commit_buffer(commit, &size);
 399         strbuf_add(&buf, buffer, size);
 400         unuse_commit_buffer(commit, buffer);
 401
 402         replace_parents(&buf, argc - 1, &argv[1]);
 403
 404         if (remove_signature(&buf)) {
 405                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 406                 warning(_("the signature will be removed in the replacement commit!"));
 407         }
 408
 409         check_mergetags(commit, argc, argv);
 410
 411         if (write_sha1_file(buf.buf, buf.len, commit_type, new.hash))
 412                 die(_("could not write replacement commit for: '%s'"), old_ref);
 413
 414         strbuf_release(&buf);
 415
 416         if (!oidcmp(&old, &new))
 417                 return error("new commit is the same as the old one: '%s'", oid_to_hex(&old));
 418
 419         return replace_object_oid(old_ref, &old, "replacement", &new, force);
 420 }
 421
 422 int cmd_replace(int argc, const char **argv, const char *prefix)
 423 {
 424         int force = 0;
 425         int raw = 0;
 426         const char *format = NULL;
 427         enum {
 428                 MODE_UNSPECIFIED = 0,
 429                 MODE_LIST,
 430                 MODE_DELETE,
 431                 MODE_EDIT,
 432                 MODE_GRAFT,
 433                 MODE_REPLACE
 434         } cmdmode = MODE_UNSPECIFIED;
 435         struct option options[] = {
 436                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 437                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 438                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 439                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 440                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
 441                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 442                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 443                 OPT_END()
 444         };
 445
 446         check_replace_refs = 0;
 447         git_config(git_default_config, NULL);
 448
 449         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 450
 451         if (!cmdmode)
 452                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 453
 454         if (format && cmdmode != MODE_LIST)
 455                 usage_msg_opt("--format cannot be used when not listing",
 456                               git_replace_usage, options);
 457
 458         if (force &&
 459             cmdmode != MODE_REPLACE &&
 460             cmdmode != MODE_EDIT &&
 461             cmdmode != MODE_GRAFT)
 462                 usage_msg_opt("-f only makes sense when writing a replacement",
 463                               git_replace_usage, options);
 464
 465         if (raw && cmdmode != MODE_EDIT)
 466                 usage_msg_opt("--raw only makes sense with --edit",
 467                               git_replace_usage, options);
 468
 469         switch (cmdmode) {
 470         case MODE_DELETE:
 471                 if (argc < 1)
 472                         usage_msg_opt("-d needs at least one argument",
 473                                       git_replace_usage, options);
 474                 return for_each_replace_name(argv, delete_replace_ref);
 475
 476         case MODE_REPLACE:
 477                 if (argc != 2)
 478                         usage_msg_opt("bad number of arguments",
 479                                       git_replace_usage, options);
 480                 return replace_object(argv[0], argv[1], force);
 481
 482         case MODE_EDIT:
 483                 if (argc != 1)
 484                         usage_msg_opt("-e needs exactly one argument",
 485                                       git_replace_usage, options);
 486                 return edit_and_replace(argv[0], force, raw);
 487
 488         case MODE_GRAFT:
 489                 if (argc < 1)
 490                         usage_msg_opt("-g needs at least one argument",
 491                                       git_replace_usage, options);
 492                 return create_graft(argc, argv, force);
 493
 494         case MODE_LIST:
 495                 if (argc > 1)
 496                         usage_msg_opt("only one pattern can be given with -l",
 497                                       git_replace_usage, options);
 498                 return list_replace_refs(argv[0], format);
 499
 500         default:
 501                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 502         }
 503 }