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