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 unsigned char *sha1,
  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, sha1_to_hex(sha1));
  48                 else { /* data->format == REPLACE_FORMAT_LONG */
  49                         unsigned char object[20];
  50                         enum object_type obj_type, repl_type;
  51
  52                         if (get_sha1(refname, object))
  53                                 return error("Failed to resolve '%s' as a valid ref.", refname);
  54
  55                         obj_type = sha1_object_info(object, NULL);
  56                         repl_type = sha1_object_info(sha1, NULL);
  57
  58                         printf("%s (%s) -> %s (%s)\n", refname, typename(obj_type),
  59                                sha1_to_hex(sha1), 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), "refs/replace/%s", full_hex);
 108                 /* read_ref() may reuse the buffer */
 109                 full_hex = ref + strlen("refs/replace/");
 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                      "refs/replace/%s",
 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, 0, 1, &err) ||
 175             ref_transaction_commit(transaction, NULL, &err))
 176                 die("%s", err.buf);
 177
 178         ref_transaction_free(transaction);
 179         return 0;
 180 }
 181
 182 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 183 {
 184         unsigned char object[20], repl[20];
 185
 186         if (get_sha1(object_ref, object))
 187                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 188         if (get_sha1(replace_ref, repl))
 189                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 190
 191         return replace_object_sha1(object_ref, object, replace_ref, repl, force);
 192 }
 193
 194 /*
 195  * Write the contents of the object named by "sha1" to the file "filename".
 196  * If "raw" is true, then the object's raw contents are printed according to
 197  * "type". Otherwise, we pretty-print the contents for human editing.
 198  */
 199 static void export_object(const unsigned char *sha1, enum object_type type,
 200                           int raw, const char *filename)
 201 {
 202         struct child_process cmd = CHILD_PROCESS_INIT;
 203         int fd;
 204
 205         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 206         if (fd < 0)
 207                 die_errno("unable to open %s for writing", filename);
 208
 209         argv_array_push(&cmd.args, "--no-replace-objects");
 210         argv_array_push(&cmd.args, "cat-file");
 211         if (raw)
 212                 argv_array_push(&cmd.args, typename(type));
 213         else
 214                 argv_array_push(&cmd.args, "-p");
 215         argv_array_push(&cmd.args, sha1_to_hex(sha1));
 216         cmd.git_cmd = 1;
 217         cmd.out = fd;
 218
 219         if (run_command(&cmd))
 220                 die("cat-file reported failure");
 221 }
 222
 223 /*
 224  * Read a previously-exported (and possibly edited) object back from "filename",
 225  * interpreting it as "type", and writing the result to the object database.
 226  * The sha1 of the written object is returned via sha1.
 227  */
 228 static void import_object(unsigned char *sha1, enum object_type type,
 229                           int raw, const char *filename)
 230 {
 231         int fd;
 232
 233         fd = open(filename, O_RDONLY);
 234         if (fd < 0)
 235                 die_errno("unable to open %s for reading", filename);
 236
 237         if (!raw && type == OBJ_TREE) {
 238                 const char *argv[] = { "mktree", NULL };
 239                 struct child_process cmd = CHILD_PROCESS_INIT;
 240                 struct strbuf result = STRBUF_INIT;
 241
 242                 cmd.argv = argv;
 243                 cmd.git_cmd = 1;
 244                 cmd.in = fd;
 245                 cmd.out = -1;
 246
 247                 if (start_command(&cmd))
 248                         die("unable to spawn mktree");
 249
 250                 if (strbuf_read(&result, cmd.out, 41) < 0)
 251                         die_errno("unable to read from mktree");
 252                 close(cmd.out);
 253
 254                 if (finish_command(&cmd))
 255                         die("mktree reported failure");
 256                 if (get_sha1_hex(result.buf, sha1) < 0)
 257                         die("mktree did not return an object name");
 258
 259                 strbuf_release(&result);
 260         } else {
 261                 struct stat st;
 262                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 263
 264                 if (fstat(fd, &st) < 0)
 265                         die_errno("unable to fstat %s", filename);
 266                 if (index_fd(sha1, fd, &st, type, NULL, flags) < 0)
 267                         die("unable to write object to database");
 268                 /* index_fd close()s fd for us */
 269         }
 270
 271         /*
 272          * No need to close(fd) here; both run-command and index-fd
 273          * will have done it for us.
 274          */
 275 }
 276
 277 static int edit_and_replace(const char *object_ref, int force, int raw)
 278 {
 279         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 280         enum object_type type;
 281         unsigned char old[20], new[20], prev[20];
 282         char ref[PATH_MAX];
 283
 284         if (get_sha1(object_ref, old) < 0)
 285                 die("Not a valid object name: '%s'", object_ref);
 286
 287         type = sha1_object_info(old, NULL);
 288         if (type < 0)
 289                 die("unable to get object type for %s", sha1_to_hex(old));
 290
 291         check_ref_valid(old, prev, ref, sizeof(ref), force);
 292
 293         export_object(old, type, raw, tmpfile);
 294         if (launch_editor(tmpfile, NULL, NULL) < 0)
 295                 die("editing object file failed");
 296         import_object(new, type, raw, tmpfile);
 297
 298         free(tmpfile);
 299
 300         if (!hashcmp(old, new))
 301                 return error("new object is the same as the old one: '%s'", sha1_to_hex(old));
 302
 303         return replace_object_sha1(object_ref, old, "replacement", new, force);
 304 }
 305
 306 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 307 {
 308         struct strbuf new_parents = STRBUF_INIT;
 309         const char *parent_start, *parent_end;
 310         int i;
 311
 312         /* find existing parents */
 313         parent_start = buf->buf;
 314         parent_start += 46; /* "tree " + "hex sha1" + "\n" */
 315         parent_end = parent_start;
 316
 317         while (starts_with(parent_end, "parent "))
 318                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 319
 320         /* prepare new parents */
 321         for (i = 0; i < argc; i++) {
 322                 unsigned char sha1[20];
 323                 if (get_sha1(argv[i], sha1) < 0)
 324                         die(_("Not a valid object name: '%s'"), argv[i]);
 325                 lookup_commit_or_die(sha1, argv[i]);
 326                 strbuf_addf(&new_parents, "parent %s\n", sha1_to_hex(sha1));
 327         }
 328
 329         /* replace existing parents with new ones */
 330         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 331                       new_parents.buf, new_parents.len);
 332
 333         strbuf_release(&new_parents);
 334 }
 335
 336 struct check_mergetag_data {
 337         int argc;
 338         const char **argv;
 339 };
 340
 341 static void check_one_mergetag(struct commit *commit,
 342                                struct commit_extra_header *extra,
 343                                void *data)
 344 {
 345         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
 346         const char *ref = mergetag_data->argv[0];
 347         unsigned char tag_sha1[20];
 348         struct tag *tag;
 349         int i;
 350
 351         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_sha1);
 352         tag = lookup_tag(tag_sha1);
 353         if (!tag)
 354                 die(_("bad mergetag in commit '%s'"), ref);
 355         if (parse_tag_buffer(tag, extra->value, extra->len))
 356                 die(_("malformed mergetag in commit '%s'"), ref);
 357
 358         /* iterate over new parents */
 359         for (i = 1; i < mergetag_data->argc; i++) {
 360                 unsigned char sha1[20];
 361                 if (get_sha1(mergetag_data->argv[i], sha1) < 0)
 362                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 363                 if (!hashcmp(tag->tagged->sha1, sha1))
 364                         return; /* found */
 365         }
 366
 367         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
 368               "use --edit instead of --graft"), ref, sha1_to_hex(tag_sha1));
 369 }
 370
 371 static void check_mergetags(struct commit *commit, int argc, const char **argv)
 372 {
 373         struct check_mergetag_data mergetag_data;
 374
 375         mergetag_data.argc = argc;
 376         mergetag_data.argv = argv;
 377         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
 378 }
 379
 380 static int create_graft(int argc, const char **argv, int force)
 381 {
 382         unsigned char old[20], new[20];
 383         const char *old_ref = argv[0];
 384         struct commit *commit;
 385         struct strbuf buf = STRBUF_INIT;
 386         const char *buffer;
 387         unsigned long size;
 388
 389         if (get_sha1(old_ref, old) < 0)
 390                 die(_("Not a valid object name: '%s'"), old_ref);
 391         commit = lookup_commit_or_die(old, old_ref);
 392
 393         buffer = get_commit_buffer(commit, &size);
 394         strbuf_add(&buf, buffer, size);
 395         unuse_commit_buffer(commit, buffer);
 396
 397         replace_parents(&buf, argc - 1, &argv[1]);
 398
 399         if (remove_signature(&buf)) {
 400                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 401                 warning(_("the signature will be removed in the replacement commit!"));
 402         }
 403
 404         check_mergetags(commit, argc, argv);
 405
 406         if (write_sha1_file(buf.buf, buf.len, commit_type, new))
 407                 die(_("could not write replacement commit for: '%s'"), old_ref);
 408
 409         strbuf_release(&buf);
 410
 411         if (!hashcmp(old, new))
 412                 return error("new commit is the same as the old one: '%s'", sha1_to_hex(old));
 413
 414         return replace_object_sha1(old_ref, old, "replacement", new, force);
 415 }
 416
 417 int cmd_replace(int argc, const char **argv, const char *prefix)
 418 {
 419         int force = 0;
 420         int raw = 0;
 421         const char *format = NULL;
 422         enum {
 423                 MODE_UNSPECIFIED = 0,
 424                 MODE_LIST,
 425                 MODE_DELETE,
 426                 MODE_EDIT,
 427                 MODE_GRAFT,
 428                 MODE_REPLACE
 429         } cmdmode = MODE_UNSPECIFIED;
 430         struct option options[] = {
 431                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 432                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 433                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 434                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 435                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
 436                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 437                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 438                 OPT_END()
 439         };
 440
 441         check_replace_refs = 0;
 442
 443         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 444
 445         if (!cmdmode)
 446                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 447
 448         if (format && cmdmode != MODE_LIST)
 449                 usage_msg_opt("--format cannot be used when not listing",
 450                               git_replace_usage, options);
 451
 452         if (force &&
 453             cmdmode != MODE_REPLACE &&
 454             cmdmode != MODE_EDIT &&
 455             cmdmode != MODE_GRAFT)
 456                 usage_msg_opt("-f only makes sense when writing a replacement",
 457                               git_replace_usage, options);
 458
 459         if (raw && cmdmode != MODE_EDIT)
 460                 usage_msg_opt("--raw only makes sense with --edit",
 461                               git_replace_usage, options);
 462
 463         switch (cmdmode) {
 464         case MODE_DELETE:
 465                 if (argc < 1)
 466                         usage_msg_opt("-d needs at least one argument",
 467                                       git_replace_usage, options);
 468                 return for_each_replace_name(argv, delete_replace_ref);
 469
 470         case MODE_REPLACE:
 471                 if (argc != 2)
 472                         usage_msg_opt("bad number of arguments",
 473                                       git_replace_usage, options);
 474                 return replace_object(argv[0], argv[1], force);
 475
 476         case MODE_EDIT:
 477                 if (argc != 1)
 478                         usage_msg_opt("-e needs exactly one argument",
 479                                       git_replace_usage, options);
 480                 return edit_and_replace(argv[0], force, raw);
 481
 482         case MODE_GRAFT:
 483                 if (argc < 1)
 484                         usage_msg_opt("-g needs at least one argument",
 485                                       git_replace_usage, options);
 486                 return create_graft(argc, argv, force);
 487
 488         case MODE_LIST:
 489                 if (argc > 1)
 490                         usage_msg_opt("only one pattern can be given with -l",
 491                                       git_replace_usage, options);
 492                 return list_replace_refs(argv[0], format);
 493
 494         default:
 495                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 496         }
 497 }