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 #define USE_THE_INDEX_COMPATIBILITY_MACROS
  15 #include "cache.h"
  16 #include "config.h"
  17 #include "builtin.h"
  18 #include "run-command.h"
  19 #include "exec-cmd.h"
  20 #include "parse-options.h"
  21 #include "strvec.h"
  22 #include "strbuf.h"
  23 #include "lockfile.h"
  24 #include "object-store.h"
  25 #include "dir.h"
  26 #include "entry.h"
  27
  28 static int trust_exit_code;
  29
  30 static const char *const builtin_difftool_usage[] = {
  31         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
  32         NULL
  33 };
  34
  35 static int difftool_config(const char *var, const char *value, void *cb)
  36 {
  37         if (!strcmp(var, "difftool.trustexitcode")) {
  38                 trust_exit_code = git_config_bool(var, value);
  39                 return 0;
  40         }
  41
  42         return git_default_config(var, value, cb);
  43 }
  44
  45 static int print_tool_help(void)
  46 {
  47         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
  48         return run_command_v_opt(argv, RUN_GIT_CMD);
  49 }
  50
  51 static int parse_index_info(char *p, int *mode1, int *mode2,
  52                             struct object_id *oid1, struct object_id *oid2,
  53                             char *status)
  54 {
  55         if (*p != ':')
  56                 return error("expected ':', got '%c'", *p);
  57         *mode1 = (int)strtol(p + 1, &p, 8);
  58         if (*p != ' ')
  59                 return error("expected ' ', got '%c'", *p);
  60         *mode2 = (int)strtol(p + 1, &p, 8);
  61         if (*p != ' ')
  62                 return error("expected ' ', got '%c'", *p);
  63         if (parse_oid_hex(++p, oid1, (const char **)&p))
  64                 return error("expected object ID, got '%s'", p);
  65         if (*p != ' ')
  66                 return error("expected ' ', got '%c'", *p);
  67         if (parse_oid_hex(++p, oid2, (const char **)&p))
  68                 return error("expected object ID, got '%s'", p);
  69         if (*p != ' ')
  70                 return error("expected ' ', got '%c'", *p);
  71         *status = *++p;
  72         if (!*status)
  73                 return error("missing status");
  74         if (p[1] && !isdigit(p[1]))
  75                 return error("unexpected trailer: '%s'", p + 1);
  76         return 0;
  77 }
  78
  79 /*
  80  * Remove any trailing slash from $workdir
  81  * before starting to avoid double slashes in symlink targets.
  82  */
  83 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
  84 {
  85         strbuf_setlen(buf, base_len);
  86         if (buf->len && buf->buf[buf->len - 1] != '/')
  87                 strbuf_addch(buf, '/');
  88         strbuf_addstr(buf, path);
  89 }
  90
  91 /*
  92  * Determine whether we can simply reuse the file in the worktree.
  93  */
  94 static int use_wt_file(const char *workdir, const char *name,
  95                        struct object_id *oid)
  96 {
  97         struct strbuf buf = STRBUF_INIT;
  98         struct stat st;
  99         int use = 0;
 100
 101         strbuf_addstr(&buf, workdir);
 102         add_path(&buf, buf.len, name);
 103
 104         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
 105                 struct object_id wt_oid;
 106                 int fd = open(buf.buf, O_RDONLY);
 107
 108                 if (fd >= 0 &&
 109                     !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
 110                         if (is_null_oid(oid)) {
 111                                 oidcpy(oid, &wt_oid);
 112                                 use = 1;
 113                         } else if (oideq(oid, &wt_oid))
 114                                 use = 1;
 115                 }
 116         }
 117
 118         strbuf_release(&buf);
 119
 120         return use;
 121 }
 122
 123 struct working_tree_entry {
 124         struct hashmap_entry entry;
 125         char path[FLEX_ARRAY];
 126 };
 127
 128 static int working_tree_entry_cmp(const void *unused_cmp_data,
 129                                   const struct hashmap_entry *eptr,
 130                                   const struct hashmap_entry *entry_or_key,
 131                                   const void *unused_keydata)
 132 {
 133         const struct working_tree_entry *a, *b;
 134
 135         a = container_of(eptr, const struct working_tree_entry, entry);
 136         b = container_of(entry_or_key, const struct working_tree_entry, entry);
 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                     const struct hashmap_entry *eptr,
 153                     const struct hashmap_entry *entry_or_key,
 154                     const void *unused_keydata)
 155 {
 156         const struct pair_entry *a, *b;
 157
 158         a = container_of(eptr, const struct pair_entry, entry);
 159         b = container_of(entry_or_key, const struct pair_entry, entry);
 160
 161         return strcmp(a->path, b->path);
 162 }
 163
 164 static void add_left_or_right(struct hashmap *map, const char *path,
 165                               const char *content, int is_right)
 166 {
 167         struct pair_entry *e, *existing;
 168
 169         FLEX_ALLOC_STR(e, path, path);
 170         hashmap_entry_init(&e->entry, strhash(path));
 171         existing = hashmap_get_entry(map, e, entry, NULL);
 172         if (existing) {
 173                 free(e);
 174                 e = existing;
 175         } else {
 176                 e->left[0] = e->right[0] = '\0';
 177                 hashmap_add(map, &e->entry);
 178         }
 179         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
 180 }
 181
 182 struct path_entry {
 183         struct hashmap_entry entry;
 184         char path[FLEX_ARRAY];
 185 };
 186
 187 static int path_entry_cmp(const void *unused_cmp_data,
 188                           const struct hashmap_entry *eptr,
 189                           const struct hashmap_entry *entry_or_key,
 190                           const void *key)
 191 {
 192         const struct path_entry *a, *b;
 193
 194         a = container_of(eptr, const struct path_entry, entry);
 195         b = container_of(entry_or_key, const struct path_entry, entry);
 196
 197         return strcmp(a->path, key ? key : b->path);
 198 }
 199
 200 static void changed_files(struct hashmap *result, const char *index_path,
 201                           const char *workdir)
 202 {
 203         struct child_process update_index = CHILD_PROCESS_INIT;
 204         struct child_process diff_files = CHILD_PROCESS_INIT;
 205         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
 206         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
 207                 NULL, NULL
 208         };
 209         FILE *fp;
 210
 211         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
 212         env[0] = index_env.buf;
 213
 214         strvec_pushl(&update_index.args,
 215                      "--git-dir", git_dir, "--work-tree", workdir,
 216                      "update-index", "--really-refresh", "-q",
 217                      "--unmerged", NULL);
 218         update_index.no_stdin = 1;
 219         update_index.no_stdout = 1;
 220         update_index.no_stderr = 1;
 221         update_index.git_cmd = 1;
 222         update_index.use_shell = 0;
 223         update_index.clean_on_exit = 1;
 224         update_index.dir = workdir;
 225         update_index.env = env;
 226         /* Ignore any errors of update-index */
 227         run_command(&update_index);
 228
 229         strvec_pushl(&diff_files.args,
 230                      "--git-dir", git_dir, "--work-tree", workdir,
 231                      "diff-files", "--name-only", "-z", NULL);
 232         diff_files.no_stdin = 1;
 233         diff_files.git_cmd = 1;
 234         diff_files.use_shell = 0;
 235         diff_files.clean_on_exit = 1;
 236         diff_files.out = -1;
 237         diff_files.dir = workdir;
 238         diff_files.env = env;
 239         if (start_command(&diff_files))
 240                 die("could not obtain raw diff");
 241         fp = xfdopen(diff_files.out, "r");
 242         while (!strbuf_getline_nul(&buf, fp)) {
 243                 struct path_entry *entry;
 244                 FLEX_ALLOC_STR(entry, path, buf.buf);
 245                 hashmap_entry_init(&entry->entry, strhash(buf.buf));
 246                 hashmap_add(result, &entry->entry);
 247         }
 248         fclose(fp);
 249         if (finish_command(&diff_files))
 250                 die("diff-files did not exit properly");
 251         strbuf_release(&index_env);
 252         strbuf_release(&buf);
 253 }
 254
 255 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
 256 {
 257         struct strbuf buf = STRBUF_INIT;
 258         strbuf_addstr(&buf, tmpdir);
 259         remove_dir_recursively(&buf, 0);
 260         if (exit_code)
 261                 warning(_("failed: %d"), exit_code);
 262         exit(exit_code);
 263 }
 264
 265 static int ensure_leading_directories(char *path)
 266 {
 267         switch (safe_create_leading_directories(path)) {
 268                 case SCLD_OK:
 269                 case SCLD_EXISTS:
 270                         return 0;
 271                 default:
 272                         return error(_("could not create leading directories "
 273                                        "of '%s'"), path);
 274         }
 275 }
 276
 277 /*
 278  * Unconditional writing of a plain regular file is what
 279  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 280  * temporary directories to be fed to a Git-unaware tool that knows how to
 281  * show a diff of two directories (e.g. "diff -r A B").
 282  *
 283  * Because the tool is Git-unaware, if a symbolic link appears in either of
 284  * these temporary directories, it will try to dereference and show the
 285  * difference of the target of the symbolic link, which is not what we want,
 286  * as the goal of the dir-diff mode is to produce an output that is logically
 287  * equivalent to what "git diff" produces.
 288  *
 289  * Most importantly, we want to get textual comparison of the result of the
 290  * readlink(2).  get_symlink() provides that---it returns the contents of
 291  * the symlink that gets written to a regular file to force the external tool
 292  * to compare the readlink(2) result as text, even on a filesystem that is
 293  * capable of doing a symbolic link.
 294  */
 295 static char *get_symlink(const struct object_id *oid, const char *path)
 296 {
 297         char *data;
 298         if (is_null_oid(oid)) {
 299                 /* The symlink is unknown to Git so read from the filesystem */
 300                 struct strbuf link = STRBUF_INIT;
 301                 if (has_symlinks) {
 302                         if (strbuf_readlink(&link, path, strlen(path)))
 303                                 die(_("could not read symlink %s"), path);
 304                 } else if (strbuf_read_file(&link, path, 128))
 305                         die(_("could not read symlink file %s"), path);
 306
 307                 data = strbuf_detach(&link, NULL);
 308         } else {
 309                 enum object_type type;
 310                 unsigned long size;
 311                 data = read_object_file(oid, &type, &size);
 312                 if (!data)
 313                         die(_("could not read object %s for symlink %s"),
 314                                 oid_to_hex(oid), path);
 315         }
 316
 317         return data;
 318 }
 319
 320 static int checkout_path(unsigned mode, struct object_id *oid,
 321                          const char *path, const struct checkout *state)
 322 {
 323         struct cache_entry *ce;
 324         int ret;
 325
 326         ce = make_transient_cache_entry(mode, oid, path, 0, NULL);
 327         ret = checkout_entry(ce, state, NULL, NULL);
 328
 329         discard_cache_entry(ce);
 330         return ret;
 331 }
 332
 333 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 334                         int argc, const char **argv)
 335 {
 336         char tmpdir[PATH_MAX];
 337         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 338         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 339         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 340         struct strbuf wtdir = STRBUF_INIT;
 341         char *lbase_dir, *rbase_dir;
 342         size_t ldir_len, rdir_len, wtdir_len;
 343         const char *workdir, *tmp;
 344         int ret = 0, i;
 345         FILE *fp;
 346         struct hashmap working_tree_dups = HASHMAP_INIT(working_tree_entry_cmp,
 347                                                         NULL);
 348         struct hashmap submodules = HASHMAP_INIT(pair_cmp, NULL);
 349         struct hashmap symlinks2 = HASHMAP_INIT(pair_cmp, NULL);
 350         struct hashmap_iter iter;
 351         struct pair_entry *entry;
 352         struct index_state wtindex;
 353         struct checkout lstate, rstate;
 354         int rc, flags = RUN_GIT_CMD, err = 0;
 355         struct child_process child = CHILD_PROCESS_INIT;
 356         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
 357         struct hashmap wt_modified, tmp_modified;
 358         int indices_loaded = 0;
 359
 360         workdir = get_git_work_tree();
 361
 362         /* Setup temp directories */
 363         tmp = getenv("TMPDIR");
 364         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
 365         if (!mkdtemp(tmpdir))
 366                 return error("could not create '%s'", tmpdir);
 367         strbuf_addf(&ldir, "%s/left/", tmpdir);
 368         strbuf_addf(&rdir, "%s/right/", tmpdir);
 369         strbuf_addstr(&wtdir, workdir);
 370         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 371                 strbuf_addch(&wtdir, '/');
 372         mkdir(ldir.buf, 0700);
 373         mkdir(rdir.buf, 0700);
 374
 375         memset(&wtindex, 0, sizeof(wtindex));
 376
 377         memset(&lstate, 0, sizeof(lstate));
 378         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 379         lstate.base_dir_len = ldir.len;
 380         lstate.force = 1;
 381         memset(&rstate, 0, sizeof(rstate));
 382         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 383         rstate.base_dir_len = rdir.len;
 384         rstate.force = 1;
 385
 386         ldir_len = ldir.len;
 387         rdir_len = rdir.len;
 388         wtdir_len = wtdir.len;
 389
 390         child.no_stdin = 1;
 391         child.git_cmd = 1;
 392         child.use_shell = 0;
 393         child.clean_on_exit = 1;
 394         child.dir = prefix;
 395         child.out = -1;
 396         strvec_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
 397                      NULL);
 398         for (i = 0; i < argc; i++)
 399                 strvec_push(&child.args, argv[i]);
 400         if (start_command(&child))
 401                 die("could not obtain raw diff");
 402         fp = xfdopen(child.out, "r");
 403
 404         /* Build index info for left and right sides of the diff */
 405         i = 0;
 406         while (!strbuf_getline_nul(&info, fp)) {
 407                 int lmode, rmode;
 408                 struct object_id loid, roid;
 409                 char status;
 410                 const char *src_path, *dst_path;
 411
 412                 if (starts_with(info.buf, "::"))
 413                         die(N_("combined diff formats('-c' and '--cc') are "
 414                                "not supported in\n"
 415                                "directory diff mode('-d' and '--dir-diff')."));
 416
 417                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 418                                      &status))
 419                         break;
 420                 if (strbuf_getline_nul(&lpath, fp))
 421                         break;
 422                 src_path = lpath.buf;
 423
 424                 i++;
 425                 if (status != 'C' && status != 'R') {
 426                         dst_path = src_path;
 427                 } else {
 428                         if (strbuf_getline_nul(&rpath, fp))
 429                                 break;
 430                         dst_path = rpath.buf;
 431                 }
 432
 433                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 434                         strbuf_reset(&buf);
 435                         strbuf_addf(&buf, "Subproject commit %s",
 436                                     oid_to_hex(&loid));
 437                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 438                         strbuf_reset(&buf);
 439                         strbuf_addf(&buf, "Subproject commit %s",
 440                                     oid_to_hex(&roid));
 441                         if (oideq(&loid, &roid))
 442                                 strbuf_addstr(&buf, "-dirty");
 443                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 444                         continue;
 445                 }
 446
 447                 if (S_ISLNK(lmode)) {
 448                         char *content = get_symlink(&loid, src_path);
 449                         add_left_or_right(&symlinks2, src_path, content, 0);
 450                         free(content);
 451                 }
 452
 453                 if (S_ISLNK(rmode)) {
 454                         char *content = get_symlink(&roid, dst_path);
 455                         add_left_or_right(&symlinks2, dst_path, content, 1);
 456                         free(content);
 457                 }
 458
 459                 if (lmode && status != 'C') {
 460                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 461                                 ret = error("could not write '%s'", src_path);
 462                                 goto finish;
 463                         }
 464                 }
 465
 466                 if (rmode && !S_ISLNK(rmode)) {
 467                         struct working_tree_entry *entry;
 468
 469                         /* Avoid duplicate working_tree entries */
 470                         FLEX_ALLOC_STR(entry, path, dst_path);
 471                         hashmap_entry_init(&entry->entry, strhash(dst_path));
 472                         if (hashmap_get(&working_tree_dups, &entry->entry,
 473                                         NULL)) {
 474                                 free(entry);
 475                                 continue;
 476                         }
 477                         hashmap_add(&working_tree_dups, &entry->entry);
 478
 479                         if (!use_wt_file(workdir, dst_path, &roid)) {
 480                                 if (checkout_path(rmode, &roid, dst_path,
 481                                                   &rstate)) {
 482                                         ret = error("could not write '%s'",
 483                                                     dst_path);
 484                                         goto finish;
 485                                 }
 486                         } else if (!is_null_oid(&roid)) {
 487                                 /*
 488                                  * Changes in the working tree need special
 489                                  * treatment since they are not part of the
 490                                  * index.
 491                                  */
 492                                 struct cache_entry *ce2 =
 493                                         make_cache_entry(&wtindex, rmode, &roid,
 494                                                          dst_path, 0, 0);
 495
 496                                 add_index_entry(&wtindex, ce2,
 497                                                 ADD_CACHE_JUST_APPEND);
 498
 499                                 add_path(&rdir, rdir_len, dst_path);
 500                                 if (ensure_leading_directories(rdir.buf)) {
 501                                         ret = error("could not create "
 502                                                     "directory for '%s'",
 503                                                     dst_path);
 504                                         goto finish;
 505                                 }
 506                                 add_path(&wtdir, wtdir_len, dst_path);
 507                                 if (symlinks) {
 508                                         if (symlink(wtdir.buf, rdir.buf)) {
 509                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 510                                                 goto finish;
 511                                         }
 512                                 } else {
 513                                         struct stat st;
 514                                         if (stat(wtdir.buf, &st))
 515                                                 st.st_mode = 0644;
 516                                         if (copy_file(rdir.buf, wtdir.buf,
 517                                                       st.st_mode)) {
 518                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 519                                                 goto finish;
 520                                         }
 521                                 }
 522                         }
 523                 }
 524         }
 525
 526         fclose(fp);
 527         fp = NULL;
 528         if (finish_command(&child)) {
 529                 ret = error("error occurred running diff --raw");
 530                 goto finish;
 531         }
 532
 533         if (!i)
 534                 goto finish;
 535
 536         /*
 537          * Changes to submodules require special treatment.This loop writes a
 538          * temporary file to both the left and right directories to show the
 539          * change in the recorded SHA1 for the submodule.
 540          */
 541         hashmap_for_each_entry(&submodules, &iter, entry,
 542                                 entry /* member name */) {
 543                 if (*entry->left) {
 544                         add_path(&ldir, ldir_len, entry->path);
 545                         ensure_leading_directories(ldir.buf);
 546                         write_file(ldir.buf, "%s", entry->left);
 547                 }
 548                 if (*entry->right) {
 549                         add_path(&rdir, rdir_len, entry->path);
 550                         ensure_leading_directories(rdir.buf);
 551                         write_file(rdir.buf, "%s", entry->right);
 552                 }
 553         }
 554
 555         /*
 556          * Symbolic links require special treatment.The standard "git diff"
 557          * shows only the link itself, not the contents of the link target.
 558          * This loop replicates that behavior.
 559          */
 560         hashmap_for_each_entry(&symlinks2, &iter, entry,
 561                                 entry /* member name */) {
 562                 if (*entry->left) {
 563                         add_path(&ldir, ldir_len, entry->path);
 564                         ensure_leading_directories(ldir.buf);
 565                         unlink(ldir.buf);
 566                         write_file(ldir.buf, "%s", entry->left);
 567                 }
 568                 if (*entry->right) {
 569                         add_path(&rdir, rdir_len, entry->path);
 570                         ensure_leading_directories(rdir.buf);
 571                         unlink(rdir.buf);
 572                         write_file(rdir.buf, "%s", entry->right);
 573                 }
 574         }
 575
 576         strbuf_release(&buf);
 577
 578         strbuf_setlen(&ldir, ldir_len);
 579         helper_argv[1] = ldir.buf;
 580         strbuf_setlen(&rdir, rdir_len);
 581         helper_argv[2] = rdir.buf;
 582
 583         if (extcmd) {
 584                 helper_argv[0] = extcmd;
 585                 flags = 0;
 586         } else
 587                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 588         rc = run_command_v_opt(helper_argv, flags);
 589
 590         /* TODO: audit for interaction with sparse-index. */
 591         ensure_full_index(&wtindex);
 592
 593         /*
 594          * If the diff includes working copy files and those
 595          * files were modified during the diff, then the changes
 596          * should be copied back to the working tree.
 597          * Do not copy back files when symlinks are used and the
 598          * external tool did not replace the original link with a file.
 599          *
 600          * These hashes are loaded lazily since they aren't needed
 601          * in the common case of --symlinks and the difftool updating
 602          * files through the symlink.
 603          */
 604         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 605         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 606
 607         for (i = 0; i < wtindex.cache_nr; i++) {
 608                 struct hashmap_entry dummy;
 609                 const char *name = wtindex.cache[i]->name;
 610                 struct stat st;
 611
 612                 add_path(&rdir, rdir_len, name);
 613                 if (lstat(rdir.buf, &st))
 614                         continue;
 615
 616                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 617                         continue;
 618
 619                 if (!indices_loaded) {
 620                         struct lock_file lock = LOCK_INIT;
 621                         strbuf_reset(&buf);
 622                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
 623                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 624                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 625                                 ret = error("could not write %s", buf.buf);
 626                                 goto finish;
 627                         }
 628                         changed_files(&wt_modified, buf.buf, workdir);
 629                         strbuf_setlen(&rdir, rdir_len);
 630                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 631                         add_path(&rdir, rdir_len, name);
 632                         indices_loaded = 1;
 633                 }
 634
 635                 hashmap_entry_init(&dummy, strhash(name));
 636                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 637                         add_path(&wtdir, wtdir_len, name);
 638                         if (hashmap_get(&wt_modified, &dummy, name)) {
 639                                 warning(_("both files modified: '%s' and '%s'."),
 640                                         wtdir.buf, rdir.buf);
 641                                 warning(_("working tree file has been left."));
 642                                 warning("%s", "");
 643                                 err = 1;
 644                         } else if (unlink(wtdir.buf) ||
 645                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 646                                 warning_errno(_("could not copy '%s' to '%s'"),
 647                                               rdir.buf, wtdir.buf);
 648                 }
 649         }
 650
 651         if (err) {
 652                 warning(_("temporary files exist in '%s'."), tmpdir);
 653                 warning(_("you may want to cleanup or recover these."));
 654                 exit(1);
 655         } else
 656                 exit_cleanup(tmpdir, rc);
 657
 658 finish:
 659         if (fp)
 660                 fclose(fp);
 661
 662         free(lbase_dir);
 663         free(rbase_dir);
 664         strbuf_release(&ldir);
 665         strbuf_release(&rdir);
 666         strbuf_release(&wtdir);
 667         strbuf_release(&buf);
 668
 669         return ret;
 670 }
 671
 672 static int run_file_diff(int prompt, const char *prefix,
 673                          int argc, const char **argv)
 674 {
 675         struct strvec args = STRVEC_INIT;
 676         const char *env[] = {
 677                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 678                 NULL
 679         };
 680         int i;
 681
 682         if (prompt > 0)
 683                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 684         else if (!prompt)
 685                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 686
 687
 688         strvec_push(&args, "diff");
 689         for (i = 0; i < argc; i++)
 690                 strvec_push(&args, argv[i]);
 691         return run_command_v_opt_cd_env(args.v, RUN_GIT_CMD, prefix, env);
 692 }
 693
 694 int cmd_difftool(int argc, const char **argv, const char *prefix)
 695 {
 696         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 697             tool_help = 0, no_index = 0;
 698         static char *difftool_cmd = NULL, *extcmd = NULL;
 699         struct option builtin_difftool_options[] = {
 700                 OPT_BOOL('g', "gui", &use_gui_tool,
 701                          N_("use `diff.guitool` instead of `diff.tool`")),
 702                 OPT_BOOL('d', "dir-diff", &dir_diff,
 703                          N_("perform a full-directory diff")),
 704                 OPT_SET_INT_F('y', "no-prompt", &prompt,
 705                         N_("do not prompt before launching a diff tool"),
 706                         0, PARSE_OPT_NONEG),
 707                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
 708                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
 709                 OPT_BOOL(0, "symlinks", &symlinks,
 710                          N_("use symlinks in dir-diff mode")),
 711                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
 712                            N_("use the specified diff tool")),
 713                 OPT_BOOL(0, "tool-help", &tool_help,
 714                          N_("print a list of diff tools that may be used with "
 715                             "`--tool`")),
 716                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 717                          N_("make 'git-difftool' exit when an invoked diff "
 718                             "tool returns a non - zero exit code")),
 719                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 720                            N_("specify a custom command for viewing diffs")),
 721                 OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
 722                 OPT_END()
 723         };
 724
 725         git_config(difftool_config, NULL);
 726         symlinks = has_symlinks;
 727
 728         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 729                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
 730                              PARSE_OPT_KEEP_DASHDASH);
 731
 732         if (tool_help)
 733                 return print_tool_help();
 734
 735         if (!no_index && !startup_info->have_repository)
 736                 die(_("difftool requires worktree or --no-index"));
 737
 738         if (!no_index){
 739                 setup_work_tree();
 740                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 741                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 742         } else if (dir_diff)
 743                 die(_("--dir-diff is incompatible with --no-index"));
 744
 745         if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
 746                 die(_("--gui, --tool and --extcmd are mutually exclusive"));
 747
 748         if (use_gui_tool)
 749                 setenv("GIT_MERGETOOL_GUI", "true", 1);
 750         else if (difftool_cmd) {
 751                 if (*difftool_cmd)
 752                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 753                 else
 754                         die(_("no <tool> given for --tool=<tool>"));
 755         }
 756
 757         if (extcmd) {
 758                 if (*extcmd)
 759                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 760                 else
 761                         die(_("no <cmd> given for --extcmd=<cmd>"));
 762         }
 763
 764         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 765                trust_exit_code ? "true" : "false", 1);
 766
 767         /*
 768          * In directory diff mode, 'git-difftool--helper' is called once
 769          * to compare the a / b directories. In file diff mode, 'git diff'
 770          * will invoke a separate instance of 'git-difftool--helper' for
 771          * each file that changed.
 772          */
 773         if (dir_diff)
 774                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
 775         return run_file_diff(prompt, prefix, argc, argv);
 776 }