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 "config.h"
  16 #include "builtin.h"
  17 #include "run-command.h"
  18 #include "exec_cmd.h"
  19 #include "parse-options.h"
  20 #include "argv-array.h"
  21 #include "strbuf.h"
  22 #include "lockfile.h"
  23 #include "dir.h"
  24
  25 static char *diff_gui_tool;
  26 static int trust_exit_code;
  27
  28 static const char *const builtin_difftool_usage[] = {
  29         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
  30         NULL
  31 };
  32
  33 static int difftool_config(const char *var, const char *value, void *cb)
  34 {
  35         if (!strcmp(var, "diff.guitool")) {
  36                 diff_gui_tool = xstrdup(value);
  37                 return 0;
  38         }
  39
  40         if (!strcmp(var, "difftool.trustexitcode")) {
  41                 trust_exit_code = git_config_bool(var, value);
  42                 return 0;
  43         }
  44
  45         return git_default_config(var, value, cb);
  46 }
  47
  48 static int print_tool_help(void)
  49 {
  50         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
  51         return run_command_v_opt(argv, RUN_GIT_CMD);
  52 }
  53
  54 static int parse_index_info(char *p, int *mode1, int *mode2,
  55                             struct object_id *oid1, struct object_id *oid2,
  56                             char *status)
  57 {
  58         if (*p != ':')
  59                 return error("expected ':', got '%c'", *p);
  60         *mode1 = (int)strtol(p + 1, &p, 8);
  61         if (*p != ' ')
  62                 return error("expected ' ', got '%c'", *p);
  63         *mode2 = (int)strtol(p + 1, &p, 8);
  64         if (*p != ' ')
  65                 return error("expected ' ', got '%c'", *p);
  66         if (get_oid_hex(++p, oid1))
  67                 return error("expected object ID, got '%s'", p + 1);
  68         p += GIT_SHA1_HEXSZ;
  69         if (*p != ' ')
  70                 return error("expected ' ', got '%c'", *p);
  71         if (get_oid_hex(++p, oid2))
  72                 return error("expected object ID, got '%s'", p + 1);
  73         p += GIT_SHA1_HEXSZ;
  74         if (*p != ' ')
  75                 return error("expected ' ', got '%c'", *p);
  76         *status = *++p;
  77         if (!*status)
  78                 return error("missing status");
  79         if (p[1] && !isdigit(p[1]))
  80                 return error("unexpected trailer: '%s'", p + 1);
  81         return 0;
  82 }
  83
  84 /*
  85  * Remove any trailing slash from $workdir
  86  * before starting to avoid double slashes in symlink targets.
  87  */
  88 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
  89 {
  90         strbuf_setlen(buf, base_len);
  91         if (buf->len && buf->buf[buf->len - 1] != '/')
  92                 strbuf_addch(buf, '/');
  93         strbuf_addstr(buf, path);
  94 }
  95
  96 /*
  97  * Determine whether we can simply reuse the file in the worktree.
  98  */
  99 static int use_wt_file(const char *workdir, const char *name,
 100                        struct object_id *oid)
 101 {
 102         struct strbuf buf = STRBUF_INIT;
 103         struct stat st;
 104         int use = 0;
 105
 106         strbuf_addstr(&buf, workdir);
 107         add_path(&buf, buf.len, name);
 108
 109         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
 110                 struct object_id wt_oid;
 111                 int fd = open(buf.buf, O_RDONLY);
 112
 113                 if (fd >= 0 &&
 114                     !index_fd(wt_oid.hash, fd, &st, OBJ_BLOB, name, 0)) {
 115                         if (is_null_oid(oid)) {
 116                                 oidcpy(oid, &wt_oid);
 117                                 use = 1;
 118                         } else if (!oidcmp(oid, &wt_oid))
 119                                 use = 1;
 120                 }
 121         }
 122
 123         strbuf_release(&buf);
 124
 125         return use;
 126 }
 127
 128 struct working_tree_entry {
 129         struct hashmap_entry entry;
 130         char path[FLEX_ARRAY];
 131 };
 132
 133 static int working_tree_entry_cmp(const void *unused_cmp_data,
 134                                   struct working_tree_entry *a,
 135                                   struct working_tree_entry *b,
 136                                   void *unused_keydata)
 137 {
 138         return strcmp(a->path, b->path);
 139 }
 140
 141 /*
 142  * The `left` and `right` entries hold paths for the symlinks hashmap,
 143  * and a SHA-1 surrounded by brief text for submodules.
 144  */
 145 struct pair_entry {
 146         struct hashmap_entry entry;
 147         char left[PATH_MAX], right[PATH_MAX];
 148         const char path[FLEX_ARRAY];
 149 };
 150
 151 static int pair_cmp(const void *unused_cmp_data,
 152                     struct pair_entry *a, struct pair_entry *b,
 153                     void *unused_keydata)
 154 {
 155         return strcmp(a->path, b->path);
 156 }
 157
 158 static void add_left_or_right(struct hashmap *map, const char *path,
 159                               const char *content, int is_right)
 160 {
 161         struct pair_entry *e, *existing;
 162
 163         FLEX_ALLOC_STR(e, path, path);
 164         hashmap_entry_init(e, strhash(path));
 165         existing = hashmap_get(map, e, NULL);
 166         if (existing) {
 167                 free(e);
 168                 e = existing;
 169         } else {
 170                 e->left[0] = e->right[0] = '\0';
 171                 hashmap_add(map, e);
 172         }
 173         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
 174 }
 175
 176 struct path_entry {
 177         struct hashmap_entry entry;
 178         char path[FLEX_ARRAY];
 179 };
 180
 181 static int path_entry_cmp(const void *unused_cmp_data,
 182                           struct path_entry *a, struct path_entry *b,
 183                           void *key)
 184 {
 185         return strcmp(a->path, key ? key : b->path);
 186 }
 187
 188 static void changed_files(struct hashmap *result, const char *index_path,
 189                           const char *workdir)
 190 {
 191         struct child_process update_index = CHILD_PROCESS_INIT;
 192         struct child_process diff_files = CHILD_PROCESS_INIT;
 193         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
 194         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
 195                 NULL, NULL
 196         };
 197         FILE *fp;
 198
 199         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
 200         env[0] = index_env.buf;
 201
 202         argv_array_pushl(&update_index.args,
 203                          "--git-dir", git_dir, "--work-tree", workdir,
 204                          "update-index", "--really-refresh", "-q",
 205                          "--unmerged", NULL);
 206         update_index.no_stdin = 1;
 207         update_index.no_stdout = 1;
 208         update_index.no_stderr = 1;
 209         update_index.git_cmd = 1;
 210         update_index.use_shell = 0;
 211         update_index.clean_on_exit = 1;
 212         update_index.dir = workdir;
 213         update_index.env = env;
 214         /* Ignore any errors of update-index */
 215         run_command(&update_index);
 216
 217         argv_array_pushl(&diff_files.args,
 218                          "--git-dir", git_dir, "--work-tree", workdir,
 219                          "diff-files", "--name-only", "-z", NULL);
 220         diff_files.no_stdin = 1;
 221         diff_files.git_cmd = 1;
 222         diff_files.use_shell = 0;
 223         diff_files.clean_on_exit = 1;
 224         diff_files.out = -1;
 225         diff_files.dir = workdir;
 226         diff_files.env = env;
 227         if (start_command(&diff_files))
 228                 die("could not obtain raw diff");
 229         fp = xfdopen(diff_files.out, "r");
 230         while (!strbuf_getline_nul(&buf, fp)) {
 231                 struct path_entry *entry;
 232                 FLEX_ALLOC_STR(entry, path, buf.buf);
 233                 hashmap_entry_init(entry, strhash(buf.buf));
 234                 hashmap_add(result, entry);
 235         }
 236         fclose(fp);
 237         if (finish_command(&diff_files))
 238                 die("diff-files did not exit properly");
 239         strbuf_release(&index_env);
 240         strbuf_release(&buf);
 241 }
 242
 243 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
 244 {
 245         struct strbuf buf = STRBUF_INIT;
 246         strbuf_addstr(&buf, tmpdir);
 247         remove_dir_recursively(&buf, 0);
 248         if (exit_code)
 249                 warning(_("failed: %d"), exit_code);
 250         exit(exit_code);
 251 }
 252
 253 static int ensure_leading_directories(char *path)
 254 {
 255         switch (safe_create_leading_directories(path)) {
 256                 case SCLD_OK:
 257                 case SCLD_EXISTS:
 258                         return 0;
 259                 default:
 260                         return error(_("could not create leading directories "
 261                                        "of '%s'"), path);
 262         }
 263 }
 264
 265 /*
 266  * Unconditional writing of a plain regular file is what
 267  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 268  * temporary directories to be fed to a Git-unaware tool that knows how to
 269  * show a diff of two directories (e.g. "diff -r A B").
 270  *
 271  * Because the tool is Git-unaware, if a symbolic link appears in either of
 272  * these temporary directories, it will try to dereference and show the
 273  * difference of the target of the symbolic link, which is not what we want,
 274  * as the goal of the dir-diff mode is to produce an output that is logically
 275  * equivalent to what "git diff" produces.
 276  *
 277  * Most importantly, we want to get textual comparison of the result of the
 278  * readlink(2).  get_symlink() provides that---it returns the contents of
 279  * the symlink that gets written to a regular file to force the external tool
 280  * to compare the readlink(2) result as text, even on a filesystem that is
 281  * capable of doing a symbolic link.
 282  */
 283 static char *get_symlink(const struct object_id *oid, const char *path)
 284 {
 285         char *data;
 286         if (is_null_oid(oid)) {
 287                 /* The symlink is unknown to Git so read from the filesystem */
 288                 struct strbuf link = STRBUF_INIT;
 289                 if (has_symlinks) {
 290                         if (strbuf_readlink(&link, path, strlen(path)))
 291                                 die(_("could not read symlink %s"), path);
 292                 } else if (strbuf_read_file(&link, path, 128))
 293                         die(_("could not read symlink file %s"), path);
 294
 295                 data = strbuf_detach(&link, NULL);
 296         } else {
 297                 enum object_type type;
 298                 unsigned long size;
 299                 data = read_sha1_file(oid->hash, &type, &size);
 300                 if (!data)
 301                         die(_("could not read object %s for symlink %s"),
 302                                 oid_to_hex(oid), path);
 303         }
 304
 305         return data;
 306 }
 307
 308 static int checkout_path(unsigned mode, struct object_id *oid,
 309                          const char *path, const struct checkout *state)
 310 {
 311         struct cache_entry *ce;
 312         int ret;
 313
 314         ce = make_cache_entry(mode, oid->hash, path, 0, 0);
 315         ret = checkout_entry(ce, state, NULL);
 316
 317         free(ce);
 318         return ret;
 319 }
 320
 321 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 322                         int argc, const char **argv)
 323 {
 324         char tmpdir[PATH_MAX];
 325         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 326         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 327         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 328         struct strbuf wtdir = STRBUF_INIT;
 329         char *lbase_dir, *rbase_dir;
 330         size_t ldir_len, rdir_len, wtdir_len;
 331         const char *workdir, *tmp;
 332         int ret = 0, i;
 333         FILE *fp;
 334         struct hashmap working_tree_dups, submodules, symlinks2;
 335         struct hashmap_iter iter;
 336         struct pair_entry *entry;
 337         struct index_state wtindex;
 338         struct checkout lstate, rstate;
 339         int rc, flags = RUN_GIT_CMD, err = 0;
 340         struct child_process child = CHILD_PROCESS_INIT;
 341         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
 342         struct hashmap wt_modified, tmp_modified;
 343         int indices_loaded = 0;
 344
 345         workdir = get_git_work_tree();
 346
 347         /* Setup temp directories */
 348         tmp = getenv("TMPDIR");
 349         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
 350         if (!mkdtemp(tmpdir))
 351                 return error("could not create '%s'", tmpdir);
 352         strbuf_addf(&ldir, "%s/left/", tmpdir);
 353         strbuf_addf(&rdir, "%s/right/", tmpdir);
 354         strbuf_addstr(&wtdir, workdir);
 355         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 356                 strbuf_addch(&wtdir, '/');
 357         mkdir(ldir.buf, 0700);
 358         mkdir(rdir.buf, 0700);
 359
 360         memset(&wtindex, 0, sizeof(wtindex));
 361
 362         memset(&lstate, 0, sizeof(lstate));
 363         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 364         lstate.base_dir_len = ldir.len;
 365         lstate.force = 1;
 366         memset(&rstate, 0, sizeof(rstate));
 367         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 368         rstate.base_dir_len = rdir.len;
 369         rstate.force = 1;
 370
 371         ldir_len = ldir.len;
 372         rdir_len = rdir.len;
 373         wtdir_len = wtdir.len;
 374
 375         hashmap_init(&working_tree_dups,
 376                      (hashmap_cmp_fn)working_tree_entry_cmp, NULL, 0);
 377         hashmap_init(&submodules, (hashmap_cmp_fn)pair_cmp, NULL, 0);
 378         hashmap_init(&symlinks2, (hashmap_cmp_fn)pair_cmp, NULL, 0);
 379
 380         child.no_stdin = 1;
 381         child.git_cmd = 1;
 382         child.use_shell = 0;
 383         child.clean_on_exit = 1;
 384         child.dir = prefix;
 385         child.out = -1;
 386         argv_array_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
 387                          NULL);
 388         for (i = 0; i < argc; i++)
 389                 argv_array_push(&child.args, argv[i]);
 390         if (start_command(&child))
 391                 die("could not obtain raw diff");
 392         fp = xfdopen(child.out, "r");
 393
 394         /* Build index info for left and right sides of the diff */
 395         i = 0;
 396         while (!strbuf_getline_nul(&info, fp)) {
 397                 int lmode, rmode;
 398                 struct object_id loid, roid;
 399                 char status;
 400                 const char *src_path, *dst_path;
 401
 402                 if (starts_with(info.buf, "::"))
 403                         die(N_("combined diff formats('-c' and '--cc') are "
 404                                "not supported in\n"
 405                                "directory diff mode('-d' and '--dir-diff')."));
 406
 407                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 408                                      &status))
 409                         break;
 410                 if (strbuf_getline_nul(&lpath, fp))
 411                         break;
 412                 src_path = lpath.buf;
 413
 414                 i++;
 415                 if (status != 'C' && status != 'R') {
 416                         dst_path = src_path;
 417                 } else {
 418                         if (strbuf_getline_nul(&rpath, fp))
 419                                 break;
 420                         dst_path = rpath.buf;
 421                 }
 422
 423                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 424                         strbuf_reset(&buf);
 425                         strbuf_addf(&buf, "Subproject commit %s",
 426                                     oid_to_hex(&loid));
 427                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 428                         strbuf_reset(&buf);
 429                         strbuf_addf(&buf, "Subproject commit %s",
 430                                     oid_to_hex(&roid));
 431                         if (!oidcmp(&loid, &roid))
 432                                 strbuf_addstr(&buf, "-dirty");
 433                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 434                         continue;
 435                 }
 436
 437                 if (S_ISLNK(lmode)) {
 438                         char *content = get_symlink(&loid, src_path);
 439                         add_left_or_right(&symlinks2, src_path, content, 0);
 440                         free(content);
 441                 }
 442
 443                 if (S_ISLNK(rmode)) {
 444                         char *content = get_symlink(&roid, dst_path);
 445                         add_left_or_right(&symlinks2, dst_path, content, 1);
 446                         free(content);
 447                 }
 448
 449                 if (lmode && status != 'C') {
 450                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 451                                 ret = error("could not write '%s'", src_path);
 452                                 goto finish;
 453                         }
 454                 }
 455
 456                 if (rmode && !S_ISLNK(rmode)) {
 457                         struct working_tree_entry *entry;
 458
 459                         /* Avoid duplicate working_tree entries */
 460                         FLEX_ALLOC_STR(entry, path, dst_path);
 461                         hashmap_entry_init(entry, strhash(dst_path));
 462                         if (hashmap_get(&working_tree_dups, entry, NULL)) {
 463                                 free(entry);
 464                                 continue;
 465                         }
 466                         hashmap_add(&working_tree_dups, entry);
 467
 468                         if (!use_wt_file(workdir, dst_path, &roid)) {
 469                                 if (checkout_path(rmode, &roid, dst_path,
 470                                                   &rstate)) {
 471                                         ret = error("could not write '%s'",
 472                                                     dst_path);
 473                                         goto finish;
 474                                 }
 475                         } else if (!is_null_oid(&roid)) {
 476                                 /*
 477                                  * Changes in the working tree need special
 478                                  * treatment since they are not part of the
 479                                  * index.
 480                                  */
 481                                 struct cache_entry *ce2 =
 482                                         make_cache_entry(rmode, roid.hash,
 483                                                          dst_path, 0, 0);
 484
 485                                 add_index_entry(&wtindex, ce2,
 486                                                 ADD_CACHE_JUST_APPEND);
 487
 488                                 add_path(&rdir, rdir_len, dst_path);
 489                                 if (ensure_leading_directories(rdir.buf)) {
 490                                         ret = error("could not create "
 491                                                     "directory for '%s'",
 492                                                     dst_path);
 493                                         goto finish;
 494                                 }
 495                                 add_path(&wtdir, wtdir_len, dst_path);
 496                                 if (symlinks) {
 497                                         if (symlink(wtdir.buf, rdir.buf)) {
 498                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 499                                                 goto finish;
 500                                         }
 501                                 } else {
 502                                         struct stat st;
 503                                         if (stat(wtdir.buf, &st))
 504                                                 st.st_mode = 0644;
 505                                         if (copy_file(rdir.buf, wtdir.buf,
 506                                                       st.st_mode)) {
 507                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 508                                                 goto finish;
 509                                         }
 510                                 }
 511                         }
 512                 }
 513         }
 514
 515         fclose(fp);
 516         fp = NULL;
 517         if (finish_command(&child)) {
 518                 ret = error("error occurred running diff --raw");
 519                 goto finish;
 520         }
 521
 522         if (!i)
 523                 goto finish;
 524
 525         /*
 526          * Changes to submodules require special treatment.This loop writes a
 527          * temporary file to both the left and right directories to show the
 528          * change in the recorded SHA1 for the submodule.
 529          */
 530         hashmap_iter_init(&submodules, &iter);
 531         while ((entry = hashmap_iter_next(&iter))) {
 532                 if (*entry->left) {
 533                         add_path(&ldir, ldir_len, entry->path);
 534                         ensure_leading_directories(ldir.buf);
 535                         write_file(ldir.buf, "%s", entry->left);
 536                 }
 537                 if (*entry->right) {
 538                         add_path(&rdir, rdir_len, entry->path);
 539                         ensure_leading_directories(rdir.buf);
 540                         write_file(rdir.buf, "%s", entry->right);
 541                 }
 542         }
 543
 544         /*
 545          * Symbolic links require special treatment.The standard "git diff"
 546          * shows only the link itself, not the contents of the link target.
 547          * This loop replicates that behavior.
 548          */
 549         hashmap_iter_init(&symlinks2, &iter);
 550         while ((entry = hashmap_iter_next(&iter))) {
 551                 if (*entry->left) {
 552                         add_path(&ldir, ldir_len, entry->path);
 553                         ensure_leading_directories(ldir.buf);
 554                         write_file(ldir.buf, "%s", entry->left);
 555                 }
 556                 if (*entry->right) {
 557                         add_path(&rdir, rdir_len, entry->path);
 558                         ensure_leading_directories(rdir.buf);
 559                         write_file(rdir.buf, "%s", entry->right);
 560                 }
 561         }
 562
 563         strbuf_release(&buf);
 564
 565         strbuf_setlen(&ldir, ldir_len);
 566         helper_argv[1] = ldir.buf;
 567         strbuf_setlen(&rdir, rdir_len);
 568         helper_argv[2] = rdir.buf;
 569
 570         if (extcmd) {
 571                 helper_argv[0] = extcmd;
 572                 flags = 0;
 573         } else
 574                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 575         rc = run_command_v_opt(helper_argv, flags);
 576
 577         /*
 578          * If the diff includes working copy files and those
 579          * files were modified during the diff, then the changes
 580          * should be copied back to the working tree.
 581          * Do not copy back files when symlinks are used and the
 582          * external tool did not replace the original link with a file.
 583          *
 584          * These hashes are loaded lazily since they aren't needed
 585          * in the common case of --symlinks and the difftool updating
 586          * files through the symlink.
 587          */
 588         hashmap_init(&wt_modified, (hashmap_cmp_fn)path_entry_cmp,
 589                      NULL, wtindex.cache_nr);
 590         hashmap_init(&tmp_modified, (hashmap_cmp_fn)path_entry_cmp,
 591                      NULL, wtindex.cache_nr);
 592
 593         for (i = 0; i < wtindex.cache_nr; i++) {
 594                 struct hashmap_entry dummy;
 595                 const char *name = wtindex.cache[i]->name;
 596                 struct stat st;
 597
 598                 add_path(&rdir, rdir_len, name);
 599                 if (lstat(rdir.buf, &st))
 600                         continue;
 601
 602                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 603                         continue;
 604
 605                 if (!indices_loaded) {
 606                         static struct lock_file lock;
 607                         strbuf_reset(&buf);
 608                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
 609                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 610                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 611                                 ret = error("could not write %s", buf.buf);
 612                                 rollback_lock_file(&lock);
 613                                 goto finish;
 614                         }
 615                         changed_files(&wt_modified, buf.buf, workdir);
 616                         strbuf_setlen(&rdir, rdir_len);
 617                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 618                         add_path(&rdir, rdir_len, name);
 619                         indices_loaded = 1;
 620                 }
 621
 622                 hashmap_entry_init(&dummy, strhash(name));
 623                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 624                         add_path(&wtdir, wtdir_len, name);
 625                         if (hashmap_get(&wt_modified, &dummy, name)) {
 626                                 warning(_("both files modified: '%s' and '%s'."),
 627                                         wtdir.buf, rdir.buf);
 628                                 warning(_("working tree file has been left."));
 629                                 warning("%s", "");
 630                                 err = 1;
 631                         } else if (unlink(wtdir.buf) ||
 632                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 633                                 warning_errno(_("could not copy '%s' to '%s'"),
 634                                               rdir.buf, wtdir.buf);
 635                 }
 636         }
 637
 638         if (err) {
 639                 warning(_("temporary files exist in '%s'."), tmpdir);
 640                 warning(_("you may want to cleanup or recover these."));
 641                 exit(1);
 642         } else
 643                 exit_cleanup(tmpdir, rc);
 644
 645 finish:
 646         if (fp)
 647                 fclose(fp);
 648
 649         free(lbase_dir);
 650         free(rbase_dir);
 651         strbuf_release(&ldir);
 652         strbuf_release(&rdir);
 653         strbuf_release(&wtdir);
 654         strbuf_release(&buf);
 655
 656         return ret;
 657 }
 658
 659 static int run_file_diff(int prompt, const char *prefix,
 660                          int argc, const char **argv)
 661 {
 662         struct argv_array args = ARGV_ARRAY_INIT;
 663         const char *env[] = {
 664                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 665                 NULL
 666         };
 667         int ret = 0, i;
 668
 669         if (prompt > 0)
 670                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 671         else if (!prompt)
 672                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 673
 674
 675         argv_array_push(&args, "diff");
 676         for (i = 0; i < argc; i++)
 677                 argv_array_push(&args, argv[i]);
 678         ret = run_command_v_opt_cd_env(args.argv, RUN_GIT_CMD, prefix, env);
 679         exit(ret);
 680 }
 681
 682 int cmd_difftool(int argc, const char **argv, const char *prefix)
 683 {
 684         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 685             tool_help = 0;
 686         static char *difftool_cmd = NULL, *extcmd = NULL;
 687         struct option builtin_difftool_options[] = {
 688                 OPT_BOOL('g', "gui", &use_gui_tool,
 689                          N_("use `diff.guitool` instead of `diff.tool`")),
 690                 OPT_BOOL('d', "dir-diff", &dir_diff,
 691                          N_("perform a full-directory diff")),
 692                 { OPTION_SET_INT, 'y', "no-prompt", &prompt, NULL,
 693                         N_("do not prompt before launching a diff tool"),
 694                         PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 0},
 695                 { OPTION_SET_INT, 0, "prompt", &prompt, NULL, NULL,
 696                         PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_HIDDEN,
 697                         NULL, 1 },
 698                 OPT_BOOL(0, "symlinks", &symlinks,
 699                          N_("use symlinks in dir-diff mode")),
 700                 OPT_STRING('t', "tool", &difftool_cmd, N_("<tool>"),
 701                            N_("use the specified diff tool")),
 702                 OPT_BOOL(0, "tool-help", &tool_help,
 703                          N_("print a list of diff tools that may be used with "
 704                             "`--tool`")),
 705                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 706                          N_("make 'git-difftool' exit when an invoked diff "
 707                             "tool returns a non - zero exit code")),
 708                 OPT_STRING('x', "extcmd", &extcmd, N_("<command>"),
 709                            N_("specify a custom command for viewing diffs")),
 710                 OPT_END()
 711         };
 712
 713         git_config(difftool_config, NULL);
 714         symlinks = has_symlinks;
 715
 716         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 717                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
 718                              PARSE_OPT_KEEP_DASHDASH);
 719
 720         if (tool_help)
 721                 return print_tool_help();
 722
 723         /* NEEDSWORK: once we no longer spawn anything, remove this */
 724         setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 725         setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 726
 727         if (use_gui_tool && diff_gui_tool && *diff_gui_tool)
 728                 setenv("GIT_DIFF_TOOL", diff_gui_tool, 1);
 729         else if (difftool_cmd) {
 730                 if (*difftool_cmd)
 731                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 732                 else
 733                         die(_("no <tool> given for --tool=<tool>"));
 734         }
 735
 736         if (extcmd) {
 737                 if (*extcmd)
 738                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 739                 else
 740                         die(_("no <cmd> given for --extcmd=<cmd>"));
 741         }
 742
 743         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 744                trust_exit_code ? "true" : "false", 1);
 745
 746         /*
 747          * In directory diff mode, 'git-difftool--helper' is called once
 748          * to compare the a / b directories. In file diff mode, 'git diff'
 749          * will invoke a separate instance of 'git-difftool--helper' for
 750          * each file that changed.
 751          */
 752         if (dir_diff)
 753                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
 754         return run_file_diff(prompt, prefix, argc, argv);
 755 }