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_lock *lock;
 159
 160         obj_type = sha1_object_info(object, NULL);
 161         repl_type = sha1_object_info(repl, NULL);
 162         if (!force && obj_type != repl_type)
 163                 die("Objects must be of the same type.\n"
 164                     "'%s' points to a replaced object of type '%s'\n"
 165                     "while '%s' points to a replacement object of type '%s'.",
 166                     object_ref, typename(obj_type),
 167                     replace_ref, typename(repl_type));
 168
 169         check_ref_valid(object, prev, ref, sizeof(ref), force);
 170
 171         lock = lock_any_ref_for_update(ref, prev, 0, NULL);
 172         if (!lock)
 173                 die("%s: cannot lock the ref", ref);
 174         if (write_ref_sha1(lock, repl, NULL) < 0)
 175                 die("%s: cannot update the ref", ref);
 176
 177         return 0;
 178 }
 179
 180 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 181 {
 182         unsigned char object[20], repl[20];
 183
 184         if (get_sha1(object_ref, object))
 185                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 186         if (get_sha1(replace_ref, repl))
 187                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 188
 189         return replace_object_sha1(object_ref, object, replace_ref, repl, force);
 190 }
 191
 192 /*
 193  * Write the contents of the object named by "sha1" to the file "filename".
 194  * If "raw" is true, then the object's raw contents are printed according to
 195  * "type". Otherwise, we pretty-print the contents for human editing.
 196  */
 197 static void export_object(const unsigned char *sha1, enum object_type type,
 198                           int raw, const char *filename)
 199 {
 200         struct child_process cmd = { NULL };
 201         int fd;
 202
 203         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 204         if (fd < 0)
 205                 die_errno("unable to open %s for writing", filename);
 206
 207         argv_array_push(&cmd.args, "--no-replace-objects");
 208         argv_array_push(&cmd.args, "cat-file");
 209         if (raw)
 210                 argv_array_push(&cmd.args, typename(type));
 211         else
 212                 argv_array_push(&cmd.args, "-p");
 213         argv_array_push(&cmd.args, sha1_to_hex(sha1));
 214         cmd.git_cmd = 1;
 215         cmd.out = fd;
 216
 217         if (run_command(&cmd))
 218                 die("cat-file reported failure");
 219 }
 220
 221 /*
 222  * Read a previously-exported (and possibly edited) object back from "filename",
 223  * interpreting it as "type", and writing the result to the object database.
 224  * The sha1 of the written object is returned via sha1.
 225  */
 226 static void import_object(unsigned char *sha1, enum object_type type,
 227                           int raw, const char *filename)
 228 {
 229         int fd;
 230
 231         fd = open(filename, O_RDONLY);
 232         if (fd < 0)
 233                 die_errno("unable to open %s for reading", filename);
 234
 235         if (!raw && type == OBJ_TREE) {
 236                 const char *argv[] = { "mktree", NULL };
 237                 struct child_process cmd = { argv };
 238                 struct strbuf result = STRBUF_INIT;
 239
 240                 cmd.argv = argv;
 241                 cmd.git_cmd = 1;
 242                 cmd.in = fd;
 243                 cmd.out = -1;
 244
 245                 if (start_command(&cmd))
 246                         die("unable to spawn mktree");
 247
 248                 if (strbuf_read(&result, cmd.out, 41) < 0)
 249                         die_errno("unable to read from mktree");
 250                 close(cmd.out);
 251
 252                 if (finish_command(&cmd))
 253                         die("mktree reported failure");
 254                 if (get_sha1_hex(result.buf, sha1) < 0)
 255                         die("mktree did not return an object name");
 256
 257                 strbuf_release(&result);
 258         } else {
 259                 struct stat st;
 260                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 261
 262                 if (fstat(fd, &st) < 0)
 263                         die_errno("unable to fstat %s", filename);
 264                 if (index_fd(sha1, fd, &st, type, NULL, flags) < 0)
 265                         die("unable to write object to database");
 266                 /* index_fd close()s fd for us */
 267         }
 268
 269         /*
 270          * No need to close(fd) here; both run-command and index-fd
 271          * will have done it for us.
 272          */
 273 }
 274
 275 static int edit_and_replace(const char *object_ref, int force, int raw)
 276 {
 277         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 278         enum object_type type;
 279         unsigned char old[20], new[20], prev[20];
 280         char ref[PATH_MAX];
 281
 282         if (get_sha1(object_ref, old) < 0)
 283                 die("Not a valid object name: '%s'", object_ref);
 284
 285         type = sha1_object_info(old, NULL);
 286         if (type < 0)
 287                 die("unable to get object type for %s", sha1_to_hex(old));
 288
 289         check_ref_valid(old, prev, ref, sizeof(ref), force);
 290
 291         export_object(old, type, raw, tmpfile);
 292         if (launch_editor(tmpfile, NULL, NULL) < 0)
 293                 die("editing object file failed");
 294         import_object(new, type, raw, tmpfile);
 295
 296         free(tmpfile);
 297
 298         if (!hashcmp(old, new))
 299                 return error("new object is the same as the old one: '%s'", sha1_to_hex(old));
 300
 301         return replace_object_sha1(object_ref, old, "replacement", new, force);
 302 }
 303
 304 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 305 {
 306         struct strbuf new_parents = STRBUF_INIT;
 307         const char *parent_start, *parent_end;
 308         int i;
 309
 310         /* find existing parents */
 311         parent_start = buf->buf;
 312         parent_start += 46; /* "tree " + "hex sha1" + "\n" */
 313         parent_end = parent_start;
 314
 315         while (starts_with(parent_end, "parent "))
 316                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 317
 318         /* prepare new parents */
 319         for (i = 0; i < argc; i++) {
 320                 unsigned char sha1[20];
 321                 if (get_sha1(argv[i], sha1) < 0)
 322                         die(_("Not a valid object name: '%s'"), argv[i]);
 323                 lookup_commit_or_die(sha1, argv[i]);
 324                 strbuf_addf(&new_parents, "parent %s\n", sha1_to_hex(sha1));
 325         }
 326
 327         /* replace existing parents with new ones */
 328         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 329                       new_parents.buf, new_parents.len);
 330
 331         strbuf_release(&new_parents);
 332 }
 333
 334 struct check_mergetag_data {
 335         int argc;
 336         const char **argv;
 337 };
 338
 339 static void check_one_mergetag(struct commit *commit,
 340                                struct commit_extra_header *extra,
 341                                void *data)
 342 {
 343         struct check_mergetag_data *mergetag_data = (struct check_mergetag_data *)data;
 344         const char *ref = mergetag_data->argv[0];
 345         unsigned char tag_sha1[20];
 346         struct tag *tag;
 347         int i;
 348
 349         hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), tag_sha1);
 350         tag = lookup_tag(tag_sha1);
 351         if (!tag)
 352                 die(_("bad mergetag in commit '%s'"), ref);
 353         if (parse_tag_buffer(tag, extra->value, extra->len))
 354                 die(_("malformed mergetag in commit '%s'"), ref);
 355
 356         /* iterate over new parents */
 357         for (i = 1; i < mergetag_data->argc; i++) {
 358                 unsigned char sha1[20];
 359                 if (get_sha1(mergetag_data->argv[i], sha1) < 0)
 360                         die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 361                 if (!hashcmp(tag->tagged->sha1, sha1))
 362                         return; /* found */
 363         }
 364
 365         die(_("original commit '%s' contains mergetag '%s' that is discarded; "
 366               "use --edit instead of --graft"), ref, sha1_to_hex(tag_sha1));
 367 }
 368
 369 static void check_mergetags(struct commit *commit, int argc, const char **argv)
 370 {
 371         struct check_mergetag_data mergetag_data;
 372
 373         mergetag_data.argc = argc;
 374         mergetag_data.argv = argv;
 375         for_each_mergetag(check_one_mergetag, commit, &mergetag_data);
 376 }
 377
 378 static int create_graft(int argc, const char **argv, int force)
 379 {
 380         unsigned char old[20], new[20];
 381         const char *old_ref = argv[0];
 382         struct commit *commit;
 383         struct strbuf buf = STRBUF_INIT;
 384         const char *buffer;
 385         unsigned long size;
 386
 387         if (get_sha1(old_ref, old) < 0)
 388                 die(_("Not a valid object name: '%s'"), old_ref);
 389         commit = lookup_commit_or_die(old, old_ref);
 390
 391         buffer = get_commit_buffer(commit, &size);
 392         strbuf_add(&buf, buffer, size);
 393         unuse_commit_buffer(commit, buffer);
 394
 395         replace_parents(&buf, argc - 1, &argv[1]);
 396
 397         if (remove_signature(&buf)) {
 398                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 399                 warning(_("the signature will be removed in the replacement commit!"));
 400         }
 401
 402         check_mergetags(commit, argc, argv);
 403
 404         if (write_sha1_file(buf.buf, buf.len, commit_type, new))
 405                 die(_("could not write replacement commit for: '%s'"), old_ref);
 406
 407         strbuf_release(&buf);
 408
 409         if (!hashcmp(old, new))
 410                 return error("new commit is the same as the old one: '%s'", sha1_to_hex(old));
 411
 412         return replace_object_sha1(old_ref, old, "replacement", new, force);
 413 }
 414
 415 int cmd_replace(int argc, const char **argv, const char *prefix)
 416 {
 417         int force = 0;
 418         int raw = 0;
 419         const char *format = NULL;
 420         enum {
 421                 MODE_UNSPECIFIED = 0,
 422                 MODE_LIST,
 423                 MODE_DELETE,
 424                 MODE_EDIT,
 425                 MODE_GRAFT,
 426                 MODE_REPLACE
 427         } cmdmode = MODE_UNSPECIFIED;
 428         struct option options[] = {
 429                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 430                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 431                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 432                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 433                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
 434                 OPT_BOOL(0, "raw", &raw, N_("do not pretty-print contents for --edit")),
 435                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 436                 OPT_END()
 437         };
 438
 439         check_replace_refs = 0;
 440
 441         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 442
 443         if (!cmdmode)
 444                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 445
 446         if (format && cmdmode != MODE_LIST)
 447                 usage_msg_opt("--format cannot be used when not listing",
 448                               git_replace_usage, options);
 449
 450         if (force &&
 451             cmdmode != MODE_REPLACE &&
 452             cmdmode != MODE_EDIT &&
 453             cmdmode != MODE_GRAFT)
 454                 usage_msg_opt("-f only makes sense when writing a replacement",
 455                               git_replace_usage, options);
 456
 457         if (raw && cmdmode != MODE_EDIT)
 458                 usage_msg_opt("--raw only makes sense with --edit",
 459                               git_replace_usage, options);
 460
 461         switch (cmdmode) {
 462         case MODE_DELETE:
 463                 if (argc < 1)
 464                         usage_msg_opt("-d needs at least one argument",
 465                                       git_replace_usage, options);
 466                 return for_each_replace_name(argv, delete_replace_ref);
 467
 468         case MODE_REPLACE:
 469                 if (argc != 2)
 470                         usage_msg_opt("bad number of arguments",
 471                                       git_replace_usage, options);
 472                 return replace_object(argv[0], argv[1], force);
 473
 474         case MODE_EDIT:
 475                 if (argc != 1)
 476                         usage_msg_opt("-e needs exactly one argument",
 477                                       git_replace_usage, options);
 478                 return edit_and_replace(argv[0], force, raw);
 479
 480         case MODE_GRAFT:
 481                 if (argc < 1)
 482                         usage_msg_opt("-g needs at least one argument",
 483                                       git_replace_usage, options);
 484                 return create_graft(argc, argv, force);
 485
 486         case MODE_LIST:
 487                 if (argc > 1)
 488                         usage_msg_opt("only one pattern can be given with -l",
 489                                       git_replace_usage, options);
 490                 return list_replace_refs(argv[0], format);
 491
 492         default:
 493                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 494         }
 495 }