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