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         struct each_ref_fn_sha1_adapter wrapped_show_reference =
  70                 {show_reference, (void *) &data};
  71
  72         if (pattern == NULL)
  73                 pattern = "*";
  74         data.pattern = pattern;
  75
  76         if (format == NULL || *format == '\0' || !strcmp(format, "short"))
  77                 data.format = REPLACE_FORMAT_SHORT;
  78         else if (!strcmp(format, "medium"))
  79                 data.format = REPLACE_FORMAT_MEDIUM;
  80         else if (!strcmp(format, "long"))
  81                 data.format = REPLACE_FORMAT_LONG;
  82         else
  83                 die("invalid replace format '%s'\n"
  84                     "valid formats are 'short', 'medium' and 'long'\n",
  85                     format);
  86
  87         for_each_replace_ref(each_ref_fn_adapter, &wrapped_show_reference);
  88
  89         return 0;
  90 }
  91
  92 typedef int (*each_replace_name_fn)(const char *name, const char *ref,
  93                                     const unsigned char *sha1);
  94
  95 static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
  96 {
  97         const char **p, *full_hex;
  98         char ref[PATH_MAX];
  99         int had_error = 0;
 100         unsigned char sha1[20];
 101
 102         for (p = argv; *p; p++) {
 103                 if (get_sha1(*p, sha1)) {
 104                         error("Failed to resolve '%s' as a valid ref.", *p);
 105                         had_error = 1;
 106                         continue;
 107                 }
 108                 full_hex = sha1_to_hex(sha1);
 109                 snprintf(ref, sizeof(ref), "refs/replace/%s", full_hex);
 110                 /* read_ref() may reuse the buffer */
 111                 full_hex = ref + strlen("refs/replace/");
 112                 if (read_ref(ref, sha1)) {
 113                         error("replace ref '%s' not found.", full_hex);
 114                         had_error = 1;
 115                         continue;
 116                 }
 117                 if (fn(full_hex, ref, sha1))
 118                         had_error = 1;
 119         }
 120         return had_error;
 121 }
 122
 123 static int delete_replace_ref(const char *name, const char *ref,
 124                               const unsigned char *sha1)
 125 {
 126         if (delete_ref(ref, sha1, 0))
 127                 return 1;
 128         printf("Deleted replace ref '%s'\n", name);
 129         return 0;
 130 }
 131
 132 static void check_ref_valid(unsigned char object[20],
 133                             unsigned char prev[20],
 134                             char *ref,
 135                             int ref_size,
 136                             int force)
 137 {
 138         if (snprintf(ref, ref_size,
 139                      "refs/replace/%s",
 140                      sha1_to_hex(object)) > ref_size - 1)
 141                 die("replace ref name too long: %.*s...", 50, ref);
 142         if (check_refname_format(ref, 0))
 143                 die("'%s' is not a valid ref name.", ref);
 144
 145         if (read_ref(ref, prev))
 146                 hashclr(prev);
 147         else if (!force)
 148                 die("replace ref '%s' already exists", ref);
 149 }
 150
 151 static int replace_object_sha1(const char *object_ref,
 152                                unsigned char object[20],
 153                                const char *replace_ref,
 154                                unsigned char repl[20],
 155                                int force)
 156 {
 157         unsigned char prev[20];
 158         enum object_type obj_type, repl_type;
 159         char ref[PATH_MAX];
 160         struct ref_transaction *transaction;
 161         struct strbuf err = STRBUF_INIT;
 162
 163         obj_type = sha1_object_info(object, NULL);
 164         repl_type = sha1_object_info(repl, 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, sizeof(ref), force);
 173
 174         transaction = ref_transaction_begin(&err);
 175         if (!transaction ||
 176             ref_transaction_update(transaction, ref, repl, prev,
 177                                    0, NULL, &err) ||
 178             ref_transaction_commit(transaction, &err))
 179                 die("%s", err.buf);
 180
 181         ref_transaction_free(transaction);
 182         return 0;
 183 }
 184
 185 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 186 {
 187         unsigned char object[20], repl[20];
 188
 189         if (get_sha1(object_ref, object))
 190                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 191         if (get_sha1(replace_ref, repl))
 192                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 193
 194         return replace_object_sha1(object_ref, object, replace_ref, repl, force);
 195 }
 196
 197 /*
 198  * Write the contents of the object named by "sha1" to the file "filename".
 199  * If "raw" is true, then the object's raw contents are printed according to
 200  * "type". Otherwise, we pretty-print the contents for human editing.
 201  */
 202 static void export_object(const unsigned char *sha1, enum object_type type,
 203                           int raw, const char *filename)
 204 {
 205         struct child_process cmd = CHILD_PROCESS_INIT;
 206         int fd;
 207
 208         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 209         if (fd < 0)
 210                 die_errno("unable to open %s for writing", filename);
 211
 212         argv_array_push(&cmd.args, "--no-replace-objects");
 213         argv_array_push(&cmd.args, "cat-file");
 214         if (raw)
 215                 argv_array_push(&cmd.args, typename(type));
 216         else
 217                 argv_array_push(&cmd.args, "-p");
 218         argv_array_push(&cmd.args, sha1_to_hex(sha1));
 219         cmd.git_cmd = 1;
 220         cmd.out = fd;
 221
 222         if (run_command(&cmd))
 223                 die("cat-file reported failure");
 224 }
 225
 226 /*
 227  * Read a previously-exported (and possibly edited) object back from "filename",
 228  * interpreting it as "type", and writing the result to the object database.
 229  * The sha1 of the written object is returned via sha1.
 230  */
 231 static void import_object(unsigned char *sha1, enum object_type type,
 232                           int raw, const char *filename)
 233 {
 234         int fd;
 235
 236         fd = open(filename, O_RDONLY);
 237         if (fd < 0)
 238                 die_errno("unable to open %s for reading", filename);
 239
 240         if (!raw && type == OBJ_TREE) {
 241                 const char *argv[] = { "mktree", NULL };
 242                 struct child_process cmd = CHILD_PROCESS_INIT;
 243                 struct strbuf result = STRBUF_INIT;
 244
 245                 cmd.argv = argv;
 246                 cmd.git_cmd = 1;
 247                 cmd.in = fd;
 248                 cmd.out = -1;
 249
 250                 if (start_command(&cmd))
 251                         die("unable to spawn mktree");
 252
 253                 if (strbuf_read(&result, cmd.out, 41) < 0)
 254                         die_errno("unable to read from mktree");
 255                 close(cmd.out);
 256
 257                 if (finish_command(&cmd))
 258                         die("mktree reported failure");
 259                 if (get_sha1_hex(result.buf, sha1) < 0)
 260                         die("mktree did not return an object name");
 261
 262                 strbuf_release(&result);
 263         } else {
 264                 struct stat st;
 265                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 266
 267                 if (fstat(fd, &st) < 0)
 268                         die_errno("unable to fstat %s", filename);
 269                 if (index_fd(sha1, fd, &st, type, NULL, flags) < 0)
 270                         die("unable to write object to database");
 271                 /* index_fd close()s fd for us */
 272         }
 273
 274         /*
 275          * No need to close(fd) here; both run-command and index-fd
 276          * will have done it for us.
 277          */
 278 }
 279
 280 static int edit_and_replace(const char *object_ref, int force, int raw)
 281 {
 282         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 283         enum object_type type;
 284         unsigned char old[20], new[20], prev[20];
 285         char ref[PATH_MAX];
 286
 287         if (get_sha1(object_ref, old) < 0)
 288                 die("Not a valid object name: '%s'", object_ref);
 289
 290         type = sha1_object_info(old, NULL);
 291         if (type < 0)
 292                 die("unable to get object type for %s", sha1_to_hex(old));
 293
 294         check_ref_valid(old, prev, ref, sizeof(ref), force);
 295
 296         export_object(old, type, raw, tmpfile);
 297         if (launch_editor(tmpfile, NULL, NULL) < 0)
 298                 die("editing object file failed");
 299         import_object(new, type, raw, tmpfile);
 300
 301         free(tmpfile);
 302
 303         if (!hashcmp(old, new))
 304                 return error("new object is the same as the old one: '%s'", sha1_to_hex(old));
 305
 306         return replace_object_sha1(object_ref, old, "replacement", new, force);
 307 }
 308
 309 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 310 {
 311         struct strbuf new_parents = STRBUF_INIT;
 312         const char *parent_start, *parent_end;
 313         int i;
 314
 315         /* find existing parents */
 316         parent_start = buf->buf;
 317         parent_start += 46; /* "tree " + "hex sha1" + "\n" */
 318         parent_end = parent_start;
 319
 320         while (starts_with(parent_end, "parent "))
 321                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 322
 323         /* prepare new parents */
 324         for (i = 0; i < argc; i++) {
 325                 unsigned char sha1[20];
 326                 if (get_sha1(argv[i], sha1) < 0)
 327                         die(_("Not a valid object name: '%s'"), argv[i]);
 328                 lookup_commit_or_die(sha1, argv[i]);
 329                 strbuf_addf(&new_parents, "parent %s\n", sha1_to_hex(sha1));
 330         }
 331
 332         /* replace existing parents with new ones */
 333         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 334                       new_parents.buf, new_parents.len);
 335
 336         strbuf_release(&new_parents);
 337 }
 338
 339 struct check_mergetag_data {
 340         int argc;
 341         const char **argv;
 342 };
 343
 344 static void check_one_mergetag(struct commit *commit,
 345                                struct commit_extra_header *extra,
 346                                void *data)
 347 {
 348         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
 349         const char *ref = mergetag_data->argv[0];
 350         unsigned char tag_sha1[20];
 351         struct tag *tag;
 352         int i;
 353
 354         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_sha1);
 355         tag = lookup_tag(tag_sha1);
 356         if (!tag)
 357                 die(_("bad mergetag in commit '%s'"), ref);
 358         if (parse_tag_buffer(tag, extra->value, extra->len))
 359                 die(_("malformed mergetag in commit '%s'"), ref);
 360
 361         /* iterate over new parents */
 362         for (i = 1; i < mergetag_data->argc; i++) {
 363                 unsigned char sha1[20];
 364                 if (get_sha1(mergetag_data->argv[i], sha1) < 0)
 365                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 366                 if (!hashcmp(tag->tagged->sha1, sha1))
 367                         return; /* found */
 368         }
 369
 370         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
 371               "use --edit instead of --graft"), ref, sha1_to_hex(tag_sha1));
 372 }
 373
 374 static void check_mergetags(struct commit *commit, int argc, const char **argv)
 375 {
 376         struct check_mergetag_data mergetag_data;
 377
 378         mergetag_data.argc = argc;
 379         mergetag_data.argv = argv;
 380         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
 381 }
 382
 383 static int create_graft(int argc, const char **argv, int force)
 384 {
 385         unsigned char old[20], new[20];
 386         const char *old_ref = argv[0];
 387         struct commit *commit;
 388         struct strbuf buf = STRBUF_INIT;
 389         const char *buffer;
 390         unsigned long size;
 391
 392         if (get_sha1(old_ref, old) < 0)
 393                 die(_("Not a valid object name: '%s'"), old_ref);
 394         commit = lookup_commit_or_die(old, old_ref);
 395
 396         buffer = get_commit_buffer(commit, &size);
 397         strbuf_add(&buf, buffer, size);
 398         unuse_commit_buffer(commit, buffer);
 399
 400         replace_parents(&buf, argc - 1, &argv[1]);
 401
 402         if (remove_signature(&buf)) {
 403                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 404                 warning(_("the signature will be removed in the replacement commit!"));
 405         }
 406
 407         check_mergetags(commit, argc, argv);
 408
 409         if (write_sha1_file(buf.buf, buf.len, commit_type, new))
 410                 die(_("could not write replacement commit for: '%s'"), old_ref);
 411
 412         strbuf_release(&buf);
 413
 414         if (!hashcmp(old, new))
 415                 return error("new commit is the same as the old one: '%s'", sha1_to_hex(old));
 416
 417         return replace_object_sha1(old_ref, old, "replacement", new, force);
 418 }
 419
 420 int cmd_replace(int argc, const char **argv, const char *prefix)
 421 {
 422         int force = 0;
 423         int raw = 0;
 424         const char *format = NULL;
 425         enum {
 426                 MODE_UNSPECIFIED = 0,
 427                 MODE_LIST,
 428                 MODE_DELETE,
 429                 MODE_EDIT,
 430                 MODE_GRAFT,
 431                 MODE_REPLACE
 432         } cmdmode = MODE_UNSPECIFIED;
 433         struct option options[] = {
 434                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 435                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 436                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 437                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 438                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
 439                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 440                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 441                 OPT_END()
 442         };
 443
 444         check_replace_refs = 0;
 445
 446         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 447
 448         if (!cmdmode)
 449                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 450
 451         if (format && cmdmode != MODE_LIST)
 452                 usage_msg_opt("--format cannot be used when not listing",
 453                               git_replace_usage, options);
 454
 455         if (force &&
 456             cmdmode != MODE_REPLACE &&
 457             cmdmode != MODE_EDIT &&
 458             cmdmode != MODE_GRAFT)
 459                 usage_msg_opt("-f only makes sense when writing a replacement",
 460                               git_replace_usage, options);
 461
 462         if (raw && cmdmode != MODE_EDIT)
 463                 usage_msg_opt("--raw only makes sense with --edit",
 464                               git_replace_usage, options);
 465
 466         switch (cmdmode) {
 467         case MODE_DELETE:
 468                 if (argc < 1)
 469                         usage_msg_opt("-d needs at least one argument",
 470                                       git_replace_usage, options);
 471                 return for_each_replace_name(argv, delete_replace_ref);
 472
 473         case MODE_REPLACE:
 474                 if (argc != 2)
 475                         usage_msg_opt("bad number of arguments",
 476                                       git_replace_usage, options);
 477                 return replace_object(argv[0], argv[1], force);
 478
 479         case MODE_EDIT:
 480                 if (argc != 1)
 481                         usage_msg_opt("-e needs exactly one argument",
 482                                       git_replace_usage, options);
 483                 return edit_and_replace(argv[0], force, raw);
 484
 485         case MODE_GRAFT:
 486                 if (argc < 1)
 487                         usage_msg_opt("-g needs at least one argument",
 488                                       git_replace_usage, options);
 489                 return create_graft(argc, argv, force);
 490
 491         case MODE_LIST:
 492                 if (argc > 1)
 493                         usage_msg_opt("only one pattern can be given with -l",
 494                                       git_replace_usage, options);
 495                 return list_replace_refs(argv[0], format);
 496
 497         default:
 498                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 499         }
 500 }