builtin/difftool.c

   1 /*
   2  * "git difftool" builtin command
   3  *
   4  * This is a wrapper around the GIT_EXTERNAL_DIFF-compatible
   5  * git-difftool--helper script.
   6  *
   7  * This script exports GIT_EXTERNAL_DIFF and GIT_PAGER for use by git.
   8  * The GIT_DIFF* variables are exported for use by git-difftool--helper.
   9  *
  10  * Any arguments that are unknown to this script are forwarded to 'git diff'.
  11  *
  12  * Copyright (C) 2016 Johannes Schindelin
  13  */
  14 #include "cache.h"
  15 #include "builtin.h"
  16 #include "run-command.h"
  17 #include "exec_cmd.h"
  18 #include "parse-options.h"
  19 #include "argv-array.h"
  20 #include "strbuf.h"
  21 #include "lockfile.h"
  22 #include "dir.h"
  23
  24 static char *diff_gui_tool;
  25 static int trust_exit_code;
  26
  27 static const char *const builtin_difftool_usage[] = {
  28         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
  29         NULL
  30 };
  31
  32 static int difftool_config(const char *var, const char *value, void *cb)
  33 {
  34         if (!strcmp(var, "diff.guitool")) {
  35                 diff_gui_tool = xstrdup(value);
  36                 return 0;
  37         }
  38
  39         if (!strcmp(var, "difftool.trustexitcode")) {
  40                 trust_exit_code = git_config_bool(var, value);
  41                 return 0;
  42         }
  43
  44         return git_default_config(var, value, cb);
  45 }
  46
  47 static int print_tool_help(void)
  48 {
  49         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
  50         return run_command_v_opt(argv, RUN_GIT_CMD);
  51 }
  52
  53 static int parse_index_info(char *p, int *mode1, int *mode2,
  54                             struct object_id *oid1, struct object_id *oid2,
  55                             char *status)
  56 {
  57         if (*p != ':')
  58                 return error("expected ':', got '%c'", *p);
  59         *mode1 = (int)strtol(p + 1, &p, 8);
  60         if (*p != ' ')
  61                 return error("expected ' ', got '%c'", *p);
  62         *mode2 = (int)strtol(p + 1, &p, 8);
  63         if (*p != ' ')
  64                 return error("expected ' ', got '%c'", *p);
  65         if (get_oid_hex(++p, oid1))
  66                 return error("expected object ID, got '%s'", p + 1);
  67         p += GIT_SHA1_HEXSZ;
  68         if (*p != ' ')
  69                 return error("expected ' ', got '%c'", *p);
  70         if (get_oid_hex(++p, oid2))
  71                 return error("expected object ID, got '%s'", p + 1);
  72         p += GIT_SHA1_HEXSZ;
  73         if (*p != ' ')
  74                 return error("expected ' ', got '%c'", *p);
  75         *status = *++p;
  76         if (!*status)
  77                 return error("missing status");
  78         if (p[1] && !isdigit(p[1]))
  79                 return error("unexpected trailer: '%s'", p + 1);
  80         return 0;
  81 }
  82
  83 /*
  84  * Remove any trailing slash from $workdir
  85  * before starting to avoid double slashes in symlink targets.
  86  */
  87 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
  88 {
  89         strbuf_setlen(buf, base_len);
  90         if (buf->len && buf->buf[buf->len - 1] != '/')
  91                 strbuf_addch(buf, '/');
  92         strbuf_addstr(buf, path);
  93 }
  94
  95 /*
  96  * Determine whether we can simply reuse the file in the worktree.
  97  */
  98 static int use_wt_file(const char *workdir, const char *name,
  99                        struct object_id *oid)
 100 {
 101         struct strbuf buf = STRBUF_INIT;
 102         struct stat st;
 103         int use = 0;
 104
 105         strbuf_addstr(&buf, workdir);
 106         add_path(&buf, buf.len, name);
 107
 108         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
 109                 struct object_id wt_oid;
 110                 int fd = open(buf.buf, O_RDONLY);
 111
 112                 if (fd >= 0 &&
 113                     !index_fd(wt_oid.hash, fd, &st, OBJ_BLOB, name, 0)) {
 114                         if (is_null_oid(oid)) {
 115                                 oidcpy(oid, &wt_oid);
 116                                 use = 1;
 117                         } else if (!oidcmp(oid, &wt_oid))
 118                                 use = 1;
 119                 }
 120         }
 121
 122         strbuf_release(&buf);
 123
 124         return use;
 125 }
 126
 127 struct working_tree_entry {
 128         struct hashmap_entry entry;
 129         char path[FLEX_ARRAY];
 130 };
 131
 132 static int working_tree_entry_cmp(struct working_tree_entry *a,
 133                                   struct working_tree_entry *b, void *keydata)
 134 {
 135         return strcmp(a->path, b->path);
 136 }
 137
 138 /*
 139  * The `left` and `right` entries hold paths for the symlinks hashmap,
 140  * and a SHA-1 surrounded by brief text for submodules.
 141  */
 142 struct pair_entry {
 143         struct hashmap_entry entry;
 144         char left[PATH_MAX], right[PATH_MAX];
 145         const char path[FLEX_ARRAY];
 146 };
 147
 148 static int pair_cmp(struct pair_entry *a, struct pair_entry *b, void *keydata)
 149 {
 150         return strcmp(a->path, b->path);
 151 }
 152
 153 static void add_left_or_right(struct hashmap *map, const char *path,
 154                               const char *content, int is_right)
 155 {
 156         struct pair_entry *e, *existing;
 157
 158         FLEX_ALLOC_STR(e, path, path);
 159         hashmap_entry_init(e, strhash(path));
 160         existing = hashmap_get(map, e, NULL);
 161         if (existing) {
 162                 free(e);
 163                 e = existing;
 164         } else {
 165                 e->left[0] = e->right[0] = '\0';
 166                 hashmap_add(map, e);
 167         }
 168         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
 169 }
 170
 171 struct path_entry {
 172         struct hashmap_entry entry;
 173         char path[FLEX_ARRAY];
 174 };
 175
 176 static int path_entry_cmp(struct path_entry *a, struct path_entry *b, void *key)
 177 {
 178         return strcmp(a->path, key ? key : b->path);
 179 }
 180
 181 static void changed_files(struct hashmap *result, const char *index_path,
 182                           const char *workdir)
 183 {
 184         struct child_process update_index = CHILD_PROCESS_INIT;
 185         struct child_process diff_files = CHILD_PROCESS_INIT;
 186         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
 187         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
 188                 NULL, NULL
 189         };
 190         FILE *fp;
 191
 192         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
 193         env[0] = index_env.buf;
 194
 195         argv_array_pushl(&update_index.args,
 196                          "--git-dir", git_dir, "--work-tree", workdir,
 197                          "update-index", "--really-refresh", "-q",
 198                          "--unmerged", NULL);
 199         update_index.no_stdin = 1;
 200         update_index.no_stdout = 1;
 201         update_index.no_stderr = 1;
 202         update_index.git_cmd = 1;
 203         update_index.use_shell = 0;
 204         update_index.clean_on_exit = 1;
 205         update_index.dir = workdir;
 206         update_index.env = env;
 207         /* Ignore any errors of update-index */
 208         run_command(&update_index);
 209
 210         argv_array_pushl(&diff_files.args,
 211                          "--git-dir", git_dir, "--work-tree", workdir,
 212                          "diff-files", "--name-only", "-z", NULL);
 213         diff_files.no_stdin = 1;
 214         diff_files.git_cmd = 1;
 215         diff_files.use_shell = 0;
 216         diff_files.clean_on_exit = 1;
 217         diff_files.out = -1;
 218         diff_files.dir = workdir;
 219         diff_files.env = env;
 220         if (start_command(&diff_files))
 221                 die("could not obtain raw diff");
 222         fp = xfdopen(diff_files.out, "r");
 223         while (!strbuf_getline_nul(&buf, fp)) {
 224                 struct path_entry *entry;
 225                 FLEX_ALLOC_STR(entry, path, buf.buf);
 226                 hashmap_entry_init(entry, strhash(buf.buf));
 227                 hashmap_add(result, entry);
 228         }
 229         if (finish_command(&diff_files))
 230                 die("diff-files did not exit properly");
 231         strbuf_release(&index_env);
 232         strbuf_release(&buf);
 233 }
 234
 235 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
 236 {
 237         struct strbuf buf = STRBUF_INIT;
 238         strbuf_addstr(&buf, tmpdir);
 239         remove_dir_recursively(&buf, 0);
 240         if (exit_code)
 241                 warning(_("failed: %d"), exit_code);
 242         exit(exit_code);
 243 }
 244
 245 static int ensure_leading_directories(char *path)
 246 {
 247         switch (safe_create_leading_directories(path)) {
 248                 case SCLD_OK:
 249                 case SCLD_EXISTS:
 250                         return 0;
 251                 default:
 252                         return error(_("could not create leading directories "
 253                                        "of '%s'"), path);
 254         }
 255 }
 256
 257 /*
 258  * Unconditional writing of a plain regular file is what
 259  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 260  * temporary directories to be fed to a Git-unaware tool that knows how to
 261  * show a diff of two directories (e.g. "diff -r A B").
 262  *
 263  * Because the tool is Git-unaware, if a symbolic link appears in either of
 264  * these temporary directories, it will try to dereference and show the
 265  * difference of the target of the symbolic link, which is not what we want,
 266  * as the goal of the dir-diff mode is to produce an output that is logically
 267  * equivalent to what "git diff" produces.
 268  *
 269  * Most importantly, we want to get textual comparison of the result of the
 270  * readlink(2).  get_symlink() provides that---it returns the contents of
 271  * the symlink that gets written to a regular file to force the external tool
 272  * to compare the readlink(2) result as text, even on a filesystem that is
 273  * capable of doing a symbolic link.
 274  */
 275 static char *get_symlink(const struct object_id *oid, const char *path)
 276 {
 277         char *data;
 278         if (is_null_oid(oid)) {
 279                 /* The symlink is unknown to Git so read from the filesystem */
 280                 struct strbuf link = STRBUF_INIT;
 281                 if (has_symlinks) {
 282                         if (strbuf_readlink(&link, path, strlen(path)))
 283                                 die(_("could not read symlink %s"), path);
 284                 } else if (strbuf_read_file(&link, path, 128))
 285                         die(_("could not read symlink file %s"), path);
 286
 287                 data = strbuf_detach(&link, NULL);
 288         } else {
 289                 enum object_type type;
 290                 unsigned long size;
 291                 data = read_sha1_file(oid->hash, &type, &size);
 292                 if (!data)
 293                         die(_("could not read object %s for symlink %s"),
 294                                 oid_to_hex(oid), path);
 295         }
 296
 297         return data;
 298 }
 299
 300 static int checkout_path(unsigned mode, struct object_id *oid,
 301                          const char *path, const struct checkout *state)
 302 {
 303         struct cache_entry *ce;
 304         int ret;
 305
 306         ce = make_cache_entry(mode, oid->hash, path, 0, 0);
 307         ret = checkout_entry(ce, state, NULL);
 308
 309         free(ce);
 310         return ret;
 311 }
 312
 313 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 314                         int argc, const char **argv)
 315 {
 316         char tmpdir[PATH_MAX];
 317         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 318         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 319         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 320         struct strbuf wtdir = STRBUF_INIT;
 321         char *lbase_dir, *rbase_dir;
 322         size_t ldir_len, rdir_len, wtdir_len;
 323         const char *workdir, *tmp;
 324         int ret = 0, i;
 325         FILE *fp;
 326         struct hashmap working_tree_dups, submodules, symlinks2;
 327         struct hashmap_iter iter;
 328         struct pair_entry *entry;
 329         struct index_state wtindex;
 330         struct checkout lstate, rstate;
 331         int rc, flags = RUN_GIT_CMD, err = 0;
 332         struct child_process child = CHILD_PROCESS_INIT;
 333         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
 334         struct hashmap wt_modified, tmp_modified;
 335         int indices_loaded = 0;
 336
 337         workdir = get_git_work_tree();
 338
 339         /* Setup temp directories */
 340         tmp = getenv("TMPDIR");
 341         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
 342         if (!mkdtemp(tmpdir))
 343                 return error("could not create '%s'", tmpdir);
 344         strbuf_addf(&ldir, "%s/left/", tmpdir);
 345         strbuf_addf(&rdir, "%s/right/", tmpdir);
 346         strbuf_addstr(&wtdir, workdir);
 347         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 348                 strbuf_addch(&wtdir, '/');
 349         mkdir(ldir.buf, 0700);
 350         mkdir(rdir.buf, 0700);
 351
 352         memset(&wtindex, 0, sizeof(wtindex));
 353
 354         memset(&lstate, 0, sizeof(lstate));
 355         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 356         lstate.base_dir_len = ldir.len;
 357         lstate.force = 1;
 358         memset(&rstate, 0, sizeof(rstate));
 359         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 360         rstate.base_dir_len = rdir.len;
 361         rstate.force = 1;
 362
 363         ldir_len = ldir.len;
 364         rdir_len = rdir.len;
 365         wtdir_len = wtdir.len;
 366
 367         hashmap_init(&working_tree_dups,
 368                      (hashmap_cmp_fn)working_tree_entry_cmp, 0);
 369         hashmap_init(&submodules, (hashmap_cmp_fn)pair_cmp, 0);
 370         hashmap_init(&symlinks2, (hashmap_cmp_fn)pair_cmp, 0);
 371
 372         child.no_stdin = 1;
 373         child.git_cmd = 1;
 374         child.use_shell = 0;
 375         child.clean_on_exit = 1;
 376         child.dir = prefix;
 377         child.out = -1;
 378         argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
 379                          NULL);
 380         for (i = 0; i < argc; i++)
 381                 argv_array_push(&child.args, argv[i]);
 382         if (start_command(&child))
 383                 die("could not obtain raw diff");
 384         fp = xfdopen(child.out, "r");
 385
 386         /* Build index info for left and right sides of the diff */
 387         i = 0;
 388         while (!strbuf_getline_nul(&info, fp)) {
 389                 int lmode, rmode;
 390                 struct object_id loid, roid;
 391                 char status;
 392                 const char *src_path, *dst_path;
 393
 394                 if (starts_with(info.buf, "::"))
 395                         die(N_("combined diff formats('-c' and '--cc') are "
 396                                "not supported in\n"
 397                                "directory diff mode('-d' and '--dir-diff')."));
 398
 399                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 400                                      &status))
 401                         break;
 402                 if (strbuf_getline_nul(&lpath, fp))
 403                         break;
 404                 src_path = lpath.buf;
 405
 406                 i++;
 407                 if (status != 'C' && status != 'R') {
 408                         dst_path = src_path;
 409                 } else {
 410                         if (strbuf_getline_nul(&rpath, fp))
 411                                 break;
 412                         dst_path = rpath.buf;
 413                 }
 414
 415                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 416                         strbuf_reset(&buf);
 417                         strbuf_addf(&buf, "Subproject commit %s",
 418                                     oid_to_hex(&loid));
 419                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 420                         strbuf_reset(&buf);
 421                         strbuf_addf(&buf, "Subproject commit %s",
 422                                     oid_to_hex(&roid));
 423                         if (!oidcmp(&loid, &roid))
 424                                 strbuf_addstr(&buf, "-dirty");
 425                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 426                         continue;
 427                 }
 428
 429                 if (S_ISLNK(lmode)) {
 430                         char *content = get_symlink(&loid, src_path);
 431                         add_left_or_right(&symlinks2, src_path, content, 0);
 432                         free(content);
 433                 }
 434
 435                 if (S_ISLNK(rmode)) {
 436                         char *content = get_symlink(&roid, dst_path);
 437                         add_left_or_right(&symlinks2, dst_path, content, 1);
 438                         free(content);
 439                 }
 440
 441                 if (lmode && status != 'C') {
 442                         if (checkout_path(lmode, &loid, src_path, &lstate))
 443                                 return error("could not write '%s'", src_path);
 444                 }
 445
 446                 if (rmode && !S_ISLNK(rmode)) {
 447                         struct working_tree_entry *entry;
 448
 449                         /* Avoid duplicate working_tree entries */
 450                         FLEX_ALLOC_STR(entry, path, dst_path);
 451                         hashmap_entry_init(entry, strhash(dst_path));
 452                         if (hashmap_get(&working_tree_dups, entry, NULL)) {
 453                                 free(entry);
 454                                 continue;
 455                         }
 456                         hashmap_add(&working_tree_dups, entry);
 457
 458                         if (!use_wt_file(workdir, dst_path, &roid)) {
 459                                 if (checkout_path(rmode, &roid, dst_path, &rstate))
 460                                         return error("could not write '%s'",
 461                                                      dst_path);
 462                         } else if (!is_null_oid(&roid)) {
 463                                 /*
 464                                  * Changes in the working tree need special
 465                                  * treatment since they are not part of the
 466                                  * index.
 467                                  */
 468                                 struct cache_entry *ce2 =
 469                                         make_cache_entry(rmode, roid.hash,
 470                                                          dst_path, 0, 0);
 471
 472                                 add_index_entry(&wtindex, ce2,
 473                                                 ADD_CACHE_JUST_APPEND);
 474
 475                                 add_path(&rdir, rdir_len, dst_path);
 476                                 if (ensure_leading_directories(rdir.buf))
 477                                         return error("could not create "
 478                                                      "directory for '%s'",
 479                                                      dst_path);
 480                                 add_path(&wtdir, wtdir_len, dst_path);
 481                                 if (symlinks) {
 482                                         if (symlink(wtdir.buf, rdir.buf)) {
 483                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 484                                                 goto finish;
 485                                         }
 486                                 } else {
 487                                         struct stat st;
 488                                         if (stat(wtdir.buf, &st))
 489                                                 st.st_mode = 0644;
 490                                         if (copy_file(rdir.buf, wtdir.buf,
 491                                                       st.st_mode)) {
 492                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 493                                                 goto finish;
 494                                         }
 495                                 }
 496                         }
 497                 }
 498         }
 499
 500         if (finish_command(&child)) {
 501                 ret = error("error occurred running diff --raw");
 502                 goto finish;
 503         }
 504
 505         if (!i)
 506                 return 0;
 507
 508         /*
 509          * Changes to submodules require special treatment.This loop writes a
 510          * temporary file to both the left and right directories to show the
 511          * change in the recorded SHA1 for the submodule.
 512          */
 513         hashmap_iter_init(&submodules, &iter);
 514         while ((entry = hashmap_iter_next(&iter))) {
 515                 if (*entry->left) {
 516                         add_path(&ldir, ldir_len, entry->path);
 517                         ensure_leading_directories(ldir.buf);
 518                         write_file(ldir.buf, "%s", entry->left);
 519                 }
 520                 if (*entry->right) {
 521                         add_path(&rdir, rdir_len, entry->path);
 522                         ensure_leading_directories(rdir.buf);
 523                         write_file(rdir.buf, "%s", entry->right);
 524                 }
 525         }
 526
 527         /*
 528          * Symbolic links require special treatment.The standard "git diff"
 529          * shows only the link itself, not the contents of the link target.
 530          * This loop replicates that behavior.
 531          */
 532         hashmap_iter_init(&symlinks2, &iter);
 533         while ((entry = hashmap_iter_next(&iter))) {
 534                 if (*entry->left) {
 535                         add_path(&ldir, ldir_len, entry->path);
 536                         ensure_leading_directories(ldir.buf);
 537                         write_file(ldir.buf, "%s", entry->left);
 538                 }
 539                 if (*entry->right) {
 540                         add_path(&rdir, rdir_len, entry->path);
 541                         ensure_leading_directories(rdir.buf);
 542                         write_file(rdir.buf, "%s", entry->right);
 543                 }
 544         }
 545
 546         strbuf_release(&buf);
 547
 548         strbuf_setlen(&ldir, ldir_len);
 549         helper_argv[1] = ldir.buf;
 550         strbuf_setlen(&rdir, rdir_len);
 551         helper_argv[2] = rdir.buf;
 552
 553         if (extcmd) {
 554                 helper_argv[0] = extcmd;
 555                 flags = 0;
 556         } else
 557                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 558         rc = run_command_v_opt(helper_argv, flags);
 559
 560         /*
 561          * If the diff includes working copy files and those
 562          * files were modified during the diff, then the changes
 563          * should be copied back to the working tree.
 564          * Do not copy back files when symlinks are used and the
 565          * external tool did not replace the original link with a file.
 566          *
 567          * These hashes are loaded lazily since they aren't needed
 568          * in the common case of --symlinks and the difftool updating
 569          * files through the symlink.
 570          */
 571         hashmap_init(&wt_modified, (hashmap_cmp_fn)path_entry_cmp,
 572                      wtindex.cache_nr);
 573         hashmap_init(&tmp_modified, (hashmap_cmp_fn)path_entry_cmp,
 574                      wtindex.cache_nr);
 575
 576         for (i = 0; i < wtindex.cache_nr; i++) {
 577                 struct hashmap_entry dummy;
 578                 const char *name = wtindex.cache[i]->name;
 579                 struct stat st;
 580
 581                 add_path(&rdir, rdir_len, name);
 582                 if (lstat(rdir.buf, &st))
 583                         continue;
 584
 585                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 586                         continue;
 587
 588                 if (!indices_loaded) {
 589                         static struct lock_file lock;
 590                         strbuf_reset(&buf);
 591                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
 592                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 593                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 594                                 ret = error("could not write %s", buf.buf);
 595                                 rollback_lock_file(&lock);
 596                                 goto finish;
 597                         }
 598                         changed_files(&wt_modified, buf.buf, workdir);
 599                         strbuf_setlen(&rdir, rdir_len);
 600                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 601                         add_path(&rdir, rdir_len, name);
 602                         indices_loaded = 1;
 603                 }
 604
 605                 hashmap_entry_init(&dummy, strhash(name));
 606                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 607                         add_path(&wtdir, wtdir_len, name);
 608                         if (hashmap_get(&wt_modified, &dummy, name)) {
 609                                 warning(_("both files modified: '%s' and '%s'."),
 610                                         wtdir.buf, rdir.buf);
 611                                 warning(_("working tree file has been left."));
 612                                 warning("%s", "");
 613                                 err = 1;
 614                         } else if (unlink(wtdir.buf) ||
 615                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 616                                 warning_errno(_("could not copy '%s' to '%s'"),
 617                                               rdir.buf, wtdir.buf);
 618                 }
 619         }
 620
 621         if (err) {
 622                 warning(_("temporary files exist in '%s'."), tmpdir);
 623                 warning(_("you may want to cleanup or recover these."));
 624                 exit(1);
 625         } else
 626                 exit_cleanup(tmpdir, rc);
 627
 628 finish:
 629         free(lbase_dir);
 630         free(rbase_dir);
 631         strbuf_release(&ldir);
 632         strbuf_release(&rdir);
 633         strbuf_release(&wtdir);
 634         strbuf_release(&buf);
 635
 636         return ret;
 637 }
 638
 639 static int run_file_diff(int prompt, const char *prefix,
 640                          int argc, const char **argv)
 641 {
 642         struct argv_array args = ARGV_ARRAY_INIT;
 643         const char *env[] = {
 644                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 645                 NULL
 646         };
 647         int ret = 0, i;
 648
 649         if (prompt > 0)
 650                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 651         else if (!prompt)
 652                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 653
 654
 655         argv_array_push(&args, "diff");
 656         for (i = 0; i < argc; i++)
 657                 argv_array_push(&args, argv[i]);
 658         ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
 659         exit(ret);
 660 }
 661
 662 int cmd_difftool(int argc, const char **argv, const char *prefix)
 663 {
 664         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 665             tool_help = 0;
 666         static char *difftool_cmd = NULL, *extcmd = NULL;
 667         struct option builtin_difftool_options[] = {
 668                 OPT_BOOL('g', "gui", &use_gui_tool,
 669                          N_("use `diff.guitool` instead of `diff.tool`")),
 670                 OPT_BOOL('d', "dir-diff", &dir_diff,
 671                          N_("perform a full-directory diff")),
 672                 { OPTION_SET_INT, 'y', "no-prompt", &prompt, NULL,
 673                         N_("do not prompt before launching a diff tool"),
 674                         PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
 675                 { OPTION_SET_INT, 0, "prompt", &prompt, NULL, NULL,
 676                         PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_HIDDEN,
 677                         NULL, 1 },
 678                 OPT_BOOL(0, "symlinks", &symlinks,
 679                          N_("use symlinks in dir-diff mode")),
 680                 OPT_STRING('t', "tool", &difftool_cmd, N_("<tool>"),
 681                            N_("use the specified diff tool")),
 682                 OPT_BOOL(0, "tool-help", &tool_help,
 683                          N_("print a list of diff tools that may be used with "
 684                             "`--tool`")),
 685                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 686                          N_("make 'git-difftool' exit when an invoked diff "
 687                             "tool returns a non - zero exit code")),
 688                 OPT_STRING('x', "extcmd", &extcmd, N_("<command>"),
 689                            N_("specify a custom command for viewing diffs")),
 690                 OPT_END()
 691         };
 692
 693         git_config(difftool_config, NULL);
 694         symlinks = has_symlinks;
 695
 696         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 697                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
 698                              PARSE_OPT_KEEP_DASHDASH);
 699
 700         if (tool_help)
 701                 return print_tool_help();
 702
 703         /* NEEDSWORK: once we no longer spawn anything, remove this */
 704         setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 705         setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 706
 707         if (use_gui_tool && diff_gui_tool && *diff_gui_tool)
 708                 setenv("GIT_DIFF_TOOL", diff_gui_tool, 1);
 709         else if (difftool_cmd) {
 710                 if (*difftool_cmd)
 711                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 712                 else
 713                         die(_("no <tool> given for --tool=<tool>"));
 714         }
 715
 716         if (extcmd) {
 717                 if (*extcmd)
 718                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 719                 else
 720                         die(_("no <cmd> given for --extcmd=<cmd>"));
 721         }
 722
 723         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 724                trust_exit_code ? "true" : "false", 1);
 725
 726         /*
 727          * In directory diff mode, 'git-difftool--helper' is called once
 728          * to compare the a / b directories. In file diff mode, 'git diff'
 729          * will invoke a separate instance of 'git-difftool--helper' for
 730          * each file that changed.
 731          */
 732         if (dir_diff)
 733                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
 734         return run_file_diff(prompt, prefix, argc, argv);
 735 }