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
  17 static const char * const git_replace_usage[] = {
  18         N_("git replace [-f] <object> <replacement>"),
  19         N_("git replace [-f] --edit <object>"),
  20         N_("git replace [-f] --graft <commit> [<parent>...]"),
  21         N_("git replace -d <object>..."),
  22         N_("git replace [--format=<format>] [-l [<pattern>]]"),
  23         NULL
  24 };
  25
  26 enum replace_format {
  27       REPLACE_FORMAT_SHORT,
  28       REPLACE_FORMAT_MEDIUM,
  29       REPLACE_FORMAT_LONG
  30 };
  31
  32 struct show_data {
  33         const char *pattern;
  34         enum replace_format format;
  35 };
  36
  37 static int show_reference(const char *refname, const unsigned char *sha1,
  38                           int flag, void *cb_data)
  39 {
  40         struct show_data *data = cb_data;
  41
  42         if (!wildmatch(data->pattern, refname, 0, NULL)) {
  43                 if (data->format == REPLACE_FORMAT_SHORT)
  44                         printf("%s\n", refname);
  45                 else if (data->format == REPLACE_FORMAT_MEDIUM)
  46                         printf("%s -> %s\n", refname, sha1_to_hex(sha1));
  47                 else { /* data->format == REPLACE_FORMAT_LONG */
  48                         unsigned char object[20];
  49                         enum object_type obj_type, repl_type;
  50
  51                         if (get_sha1(refname, object))
  52                                 return error("Failed to resolve '%s' as a valid ref.", refname);
  53
  54                         obj_type = sha1_object_info(object, NULL);
  55                         repl_type = sha1_object_info(sha1, NULL);
  56
  57                         printf("%s (%s) -> %s (%s)\n", refname, typename(obj_type),
  58                                sha1_to_hex(sha1), typename(repl_type));
  59                 }
  60         }
  61
  62         return 0;
  63 }
  64
  65 static int list_replace_refs(const char *pattern, const char *format)
  66 {
  67         struct show_data data;
  68
  69         if (pattern == NULL)
  70                 pattern = "*";
  71         data.pattern = pattern;
  72
  73         if (format == NULL || *format == '\0' || !strcmp(format, "short"))
  74                 data.format = REPLACE_FORMAT_SHORT;
  75         else if (!strcmp(format, "medium"))
  76                 data.format = REPLACE_FORMAT_MEDIUM;
  77         else if (!strcmp(format, "long"))
  78                 data.format = REPLACE_FORMAT_LONG;
  79         else
  80                 die("invalid replace format '%s'\n"
  81                     "valid formats are 'short', 'medium' and 'long'\n",
  82                     format);
  83
  84         for_each_replace_ref(show_reference, (void *) &data);
  85
  86         return 0;
  87 }
  88
  89 typedef int (*each_replace_name_fn)(const char *name, const char *ref,
  90                                     const unsigned char *sha1);
  91
  92 static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
  93 {
  94         const char **p, *full_hex;
  95         char ref[PATH_MAX];
  96         int had_error = 0;
  97         unsigned char sha1[20];
  98
  99         for (p = argv; *p; p++) {
 100                 if (get_sha1(*p, sha1)) {
 101                         error("Failed to resolve '%s' as a valid ref.", *p);
 102                         had_error = 1;
 103                         continue;
 104                 }
 105                 full_hex = sha1_to_hex(sha1);
 106                 snprintf(ref, sizeof(ref), "refs/replace/%s", full_hex);
 107                 /* read_ref() may reuse the buffer */
 108                 full_hex = ref + strlen("refs/replace/");
 109                 if (read_ref(ref, sha1)) {
 110                         error("replace ref '%s' not found.", full_hex);
 111                         had_error = 1;
 112                         continue;
 113                 }
 114                 if (fn(full_hex, ref, sha1))
 115                         had_error = 1;
 116         }
 117         return had_error;
 118 }
 119
 120 static int delete_replace_ref(const char *name, const char *ref,
 121                               const unsigned char *sha1)
 122 {
 123         if (delete_ref(ref, sha1, 0))
 124                 return 1;
 125         printf("Deleted replace ref '%s'\n", name);
 126         return 0;
 127 }
 128
 129 static void check_ref_valid(unsigned char object[20],
 130                             unsigned char prev[20],
 131                             char *ref,
 132                             int ref_size,
 133                             int force)
 134 {
 135         if (snprintf(ref, ref_size,
 136                      "refs/replace/%s",
 137                      sha1_to_hex(object)) > ref_size - 1)
 138                 die("replace ref name too long: %.*s...", 50, ref);
 139         if (check_refname_format(ref, 0))
 140                 die("'%s' is not a valid ref name.", ref);
 141
 142         if (read_ref(ref, prev))
 143                 hashclr(prev);
 144         else if (!force)
 145                 die("replace ref '%s' already exists", ref);
 146 }
 147
 148 static int replace_object_sha1(const char *object_ref,
 149                                unsigned char object[20],
 150                                const char *replace_ref,
 151                                unsigned char repl[20],
 152                                int force)
 153 {
 154         unsigned char prev[20];
 155         enum object_type obj_type, repl_type;
 156         char ref[PATH_MAX];
 157         struct ref_lock *lock;
 158
 159         obj_type = sha1_object_info(object, NULL);
 160         repl_type = sha1_object_info(repl, NULL);
 161         if (!force && obj_type != repl_type)
 162                 die("Objects must be of the same type.\n"
 163                     "'%s' points to a replaced object of type '%s'\n"
 164                     "while '%s' points to a replacement object of type '%s'.",
 165                     object_ref, typename(obj_type),
 166                     replace_ref, typename(repl_type));
 167
 168         check_ref_valid(object, prev, ref, sizeof(ref), force);
 169
 170         lock = lock_any_ref_for_update(ref, prev, 0, NULL);
 171         if (!lock)
 172                 die("%s: cannot lock the ref", ref);
 173         if (write_ref_sha1(lock, repl, NULL) < 0)
 174                 die("%s: cannot update the ref", ref);
 175
 176         return 0;
 177 }
 178
 179 static int replace_object(const char *object_ref, const char *replace_ref, int force)
 180 {
 181         unsigned char object[20], repl[20];
 182
 183         if (get_sha1(object_ref, object))
 184                 die("Failed to resolve '%s' as a valid ref.", object_ref);
 185         if (get_sha1(replace_ref, repl))
 186                 die("Failed to resolve '%s' as a valid ref.", replace_ref);
 187
 188         return replace_object_sha1(object_ref, object, replace_ref, repl, force);
 189 }
 190
 191 /*
 192  * Write the contents of the object named by "sha1" to the file "filename",
 193  * pretty-printed for human editing based on its type.
 194  */
 195 static void export_object(const unsigned char *sha1, const char *filename)
 196 {
 197         const char *argv[] = { "--no-replace-objects", "cat-file", "-p", NULL, NULL };
 198         struct child_process cmd = { argv };
 199         int fd;
 200
 201         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 202         if (fd < 0)
 203                 die_errno("unable to open %s for writing", filename);
 204
 205         argv[3] = sha1_to_hex(sha1);
 206         cmd.git_cmd = 1;
 207         cmd.out = fd;
 208
 209         if (run_command(&cmd))
 210                 die("cat-file reported failure");
 211
 212         close(fd);
 213 }
 214
 215 /*
 216  * Read a previously-exported (and possibly edited) object back from "filename",
 217  * interpreting it as "type", and writing the result to the object database.
 218  * The sha1 of the written object is returned via sha1.
 219  */
 220 static void import_object(unsigned char *sha1, enum object_type type,
 221                           const char *filename)
 222 {
 223         int fd;
 224
 225         fd = open(filename, O_RDONLY);
 226         if (fd < 0)
 227                 die_errno("unable to open %s for reading", filename);
 228
 229         if (type == OBJ_TREE) {
 230                 const char *argv[] = { "mktree", NULL };
 231                 struct child_process cmd = { argv };
 232                 struct strbuf result = STRBUF_INIT;
 233
 234                 cmd.argv = argv;
 235                 cmd.git_cmd = 1;
 236                 cmd.in = fd;
 237                 cmd.out = -1;
 238
 239                 if (start_command(&cmd))
 240                         die("unable to spawn mktree");
 241
 242                 if (strbuf_read(&result, cmd.out, 41) < 0)
 243                         die_errno("unable to read from mktree");
 244                 close(cmd.out);
 245
 246                 if (finish_command(&cmd))
 247                         die("mktree reported failure");
 248                 if (get_sha1_hex(result.buf, sha1) < 0)
 249                         die("mktree did not return an object name");
 250
 251                 strbuf_release(&result);
 252         } else {
 253                 struct stat st;
 254                 int flags = HASH_FORMAT_CHECK | HASH_WRITE_OBJECT;
 255
 256                 if (fstat(fd, &st) < 0)
 257                         die_errno("unable to fstat %s", filename);
 258                 if (index_fd(sha1, fd, &st, type, NULL, flags) < 0)
 259                         die("unable to write object to database");
 260                 /* index_fd close()s fd for us */
 261         }
 262
 263         /*
 264          * No need to close(fd) here; both run-command and index-fd
 265          * will have done it for us.
 266          */
 267 }
 268
 269 static int edit_and_replace(const char *object_ref, int force)
 270 {
 271         char *tmpfile = git_pathdup("REPLACE_EDITOBJ");
 272         enum object_type type;
 273         unsigned char old[20], new[20], prev[20];
 274         char ref[PATH_MAX];
 275
 276         if (get_sha1(object_ref, old) < 0)
 277                 die("Not a valid object name: '%s'", object_ref);
 278
 279         type = sha1_object_info(old, NULL);
 280         if (type < 0)
 281                 die("unable to get object type for %s", sha1_to_hex(old));
 282
 283         check_ref_valid(old, prev, ref, sizeof(ref), force);
 284
 285         export_object(old, tmpfile);
 286         if (launch_editor(tmpfile, NULL, NULL) < 0)
 287                 die("editing object file failed");
 288         import_object(new, type, tmpfile);
 289
 290         free(tmpfile);
 291
 292         if (!hashcmp(old, new))
 293                 return error("new object is the same as the old one: '%s'", sha1_to_hex(old));
 294
 295         return replace_object_sha1(object_ref, old, "replacement", new, force);
 296 }
 297
 298 static void replace_parents(struct strbuf *buf, int argc, const char **argv)
 299 {
 300         struct strbuf new_parents = STRBUF_INIT;
 301         const char *parent_start, *parent_end;
 302         int i;
 303
 304         /* find existing parents */
 305         parent_start = buf->buf;
 306         parent_start += 46; /* "tree " + "hex sha1" + "\n" */
 307         parent_end = parent_start;
 308
 309         while (starts_with(parent_end, "parent "))
 310                 parent_end += 48; /* "parent " + "hex sha1" + "\n" */
 311
 312         /* prepare new parents */
 313         for (i = 0; i < argc; i++) {
 314                 unsigned char sha1[20];
 315                 if (get_sha1(argv[i], sha1) < 0)
 316                         die(_("Not a valid object name: '%s'"), argv[i]);
 317                 lookup_commit_or_die(sha1, argv[i]);
 318                 strbuf_addf(&new_parents, "parent %s\n", sha1_to_hex(sha1));
 319         }
 320
 321         /* replace existing parents with new ones */
 322         strbuf_splice(buf, parent_start - buf->buf, parent_end - parent_start,
 323                       new_parents.buf, new_parents.len);
 324
 325         strbuf_release(&new_parents);
 326 }
 327
 328 static int create_graft(int argc, const char **argv, int force)
 329 {
 330         unsigned char old[20], new[20];
 331         const char *old_ref = argv[0];
 332         struct commit *commit;
 333         struct strbuf buf = STRBUF_INIT;
 334         const char *buffer;
 335         unsigned long size;
 336
 337         if (get_sha1(old_ref, old) < 0)
 338                 die(_("Not a valid object name: '%s'"), old_ref);
 339         commit = lookup_commit_or_die(old, old_ref);
 340
 341         buffer = get_commit_buffer(commit, &size);
 342         strbuf_add(&buf, buffer, size);
 343         unuse_commit_buffer(commit, buffer);
 344
 345         replace_parents(&buf, argc - 1, &argv[1]);
 346
 347         if (remove_signature(&buf)) {
 348                 warning(_("the original commit '%s' has a gpg signature."), old_ref);
 349                 warning(_("the signature will be removed in the replacement commit!"));
 350         }
 351
 352         if (write_sha1_file(buf.buf, buf.len, commit_type, new))
 353                 die(_("could not write replacement commit for: '%s'"), old_ref);
 354
 355         strbuf_release(&buf);
 356
 357         if (!hashcmp(old, new))
 358                 return error("new commit is the same as the old one: '%s'", sha1_to_hex(old));
 359
 360         return replace_object_sha1(old_ref, old, "replacement", new, force);
 361 }
 362
 363 int cmd_replace(int argc, const char **argv, const char *prefix)
 364 {
 365         int force = 0;
 366         const char *format = NULL;
 367         enum {
 368                 MODE_UNSPECIFIED = 0,
 369                 MODE_LIST,
 370                 MODE_DELETE,
 371                 MODE_EDIT,
 372                 MODE_GRAFT,
 373                 MODE_REPLACE
 374         } cmdmode = MODE_UNSPECIFIED;
 375         struct option options[] = {
 376                 OPT_CMDMODE('l', "list", &cmdmode, N_("list replace refs"), MODE_LIST),
 377                 OPT_CMDMODE('d', "delete", &cmdmode, N_("delete replace refs"), MODE_DELETE),
 378                 OPT_CMDMODE('e', "edit", &cmdmode, N_("edit existing object"), MODE_EDIT),
 379                 OPT_CMDMODE('g', "graft", &cmdmode, N_("change a commit's parents"), MODE_GRAFT),
 380                 OPT_BOOL('f', "force", &force, N_("replace the ref if it exists")),
 381                 OPT_STRING(0, "format", &format, N_("format"), N_("use this format")),
 382                 OPT_END()
 383         };
 384
 385         check_replace_refs = 0;
 386
 387         argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0);
 388
 389         if (!cmdmode)
 390                 cmdmode = argc ? MODE_REPLACE : MODE_LIST;
 391
 392         if (format && cmdmode != MODE_LIST)
 393                 usage_msg_opt("--format cannot be used when not listing",
 394                               git_replace_usage, options);
 395
 396         if (force &&
 397             cmdmode != MODE_REPLACE &&
 398             cmdmode != MODE_EDIT &&
 399             cmdmode != MODE_GRAFT)
 400                 usage_msg_opt("-f only makes sense when writing a replacement",
 401                               git_replace_usage, options);
 402
 403         switch (cmdmode) {
 404         case MODE_DELETE:
 405                 if (argc < 1)
 406                         usage_msg_opt("-d needs at least one argument",
 407                                       git_replace_usage, options);
 408                 return for_each_replace_name(argv, delete_replace_ref);
 409
 410         case MODE_REPLACE:
 411                 if (argc != 2)
 412                         usage_msg_opt("bad number of arguments",
 413                                       git_replace_usage, options);
 414                 return replace_object(argv[0], argv[1], force);
 415
 416         case MODE_EDIT:
 417                 if (argc != 1)
 418                         usage_msg_opt("-e needs exactly one argument",
 419                                       git_replace_usage, options);
 420                 return edit_and_replace(argv[0], force);
 421
 422         case MODE_GRAFT:
 423                 if (argc < 1)
 424                         usage_msg_opt("-g needs at least one argument",
 425                                       git_replace_usage, options);
 426                 return create_graft(argc, argv, force);
 427
 428         case MODE_LIST:
 429                 if (argc > 1)
 430                         usage_msg_opt("only one pattern can be given with -l",
 431                                       git_replace_usage, options);
 432                 return list_replace_refs(argv[0], format);
 433
 434         default:
 435                 die("BUG: invalid cmdmode %d", (int)cmdmode);
 436         }
 437 }