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
  27 static int trust_exit_code;
  28
  29 static const char *const builtin_difftool_usage[] = {
  30         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
  31         NULL
  32 };
  33
  34 static int difftool_config(const char *var, const char *value, void *cb)
  35 {
  36         if (!strcmp(var, "difftool.trustexitcode")) {
  37                 trust_exit_code = git_config_bool(var, value);
  38                 return 0;
  39         }
  40
  41         return git_default_config(var, value, cb);
  42 }
  43
  44 static int print_tool_help(void)
  45 {
  46         const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
  47         return run_command_v_opt(argv, RUN_GIT_CMD);
  48 }
  49
  50 static int parse_index_info(char *p, int *mode1, int *mode2,
  51                             struct object_id *oid1, struct object_id *oid2,
  52                             char *status)
  53 {
  54         if (*p != ':')
  55                 return error("expected ':', got '%c'", *p);
  56         *mode1 = (int)strtol(p + 1, &p, 8);
  57         if (*p != ' ')
  58                 return error("expected ' ', got '%c'", *p);
  59         *mode2 = (int)strtol(p + 1, &p, 8);
  60         if (*p != ' ')
  61                 return error("expected ' ', got '%c'", *p);
  62         if (parse_oid_hex(++p, oid1, (const char **)&p))
  63                 return error("expected object ID, got '%s'", p);
  64         if (*p != ' ')
  65                 return error("expected ' ', got '%c'", *p);
  66         if (parse_oid_hex(++p, oid2, (const char **)&p))
  67                 return error("expected object ID, got '%s'", p);
  68         if (*p != ' ')
  69                 return error("expected ' ', got '%c'", *p);
  70         *status = *++p;
  71         if (!*status)
  72                 return error("missing status");
  73         if (p[1] && !isdigit(p[1]))
  74                 return error("unexpected trailer: '%s'", p + 1);
  75         return 0;
  76 }
  77
  78 /*
  79  * Remove any trailing slash from $workdir
  80  * before starting to avoid double slashes in symlink targets.
  81  */
  82 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
  83 {
  84         strbuf_setlen(buf, base_len);
  85         if (buf->len && buf->buf[buf->len - 1] != '/')
  86                 strbuf_addch(buf, '/');
  87         strbuf_addstr(buf, path);
  88 }
  89
  90 /*
  91  * Determine whether we can simply reuse the file in the worktree.
  92  */
  93 static int use_wt_file(const char *workdir, const char *name,
  94                        struct object_id *oid)
  95 {
  96         struct strbuf buf = STRBUF_INIT;
  97         struct stat st;
  98         int use = 0;
  99
 100         strbuf_addstr(&buf, workdir);
 101         add_path(&buf, buf.len, name);
 102
 103         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
 104                 struct object_id wt_oid;
 105                 int fd = open(buf.buf, O_RDONLY);
 106
 107                 if (fd >= 0 &&
 108                     !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
 109                         if (is_null_oid(oid)) {
 110                                 oidcpy(oid, &wt_oid);
 111                                 use = 1;
 112                         } else if (oideq(oid, &wt_oid))
 113                                 use = 1;
 114                 }
 115         }
 116
 117         strbuf_release(&buf);
 118
 119         return use;
 120 }
 121
 122 struct working_tree_entry {
 123         struct hashmap_entry entry;
 124         char path[FLEX_ARRAY];
 125 };
 126
 127 static int working_tree_entry_cmp(const void *unused_cmp_data,
 128                                   const struct hashmap_entry *eptr,
 129                                   const struct hashmap_entry *entry_or_key,
 130                                   const void *unused_keydata)
 131 {
 132         const struct working_tree_entry *a, *b;
 133
 134         a = container_of(eptr, const struct working_tree_entry, entry);
 135         b = container_of(entry_or_key, const struct working_tree_entry, entry);
 136
 137         return strcmp(a->path, b->path);
 138 }
 139
 140 /*
 141  * The `left` and `right` entries hold paths for the symlinks hashmap,
 142  * and a SHA-1 surrounded by brief text for submodules.
 143  */
 144 struct pair_entry {
 145         struct hashmap_entry entry;
 146         char left[PATH_MAX], right[PATH_MAX];
 147         const char path[FLEX_ARRAY];
 148 };
 149
 150 static int pair_cmp(const void *unused_cmp_data,
 151                     const struct hashmap_entry *eptr,
 152                     const struct hashmap_entry *entry_or_key,
 153                     const void *unused_keydata)
 154 {
 155         const struct pair_entry *a, *b;
 156
 157         a = container_of(eptr, const struct pair_entry, entry);
 158         b = container_of(entry_or_key, const struct pair_entry, entry);
 159
 160         return strcmp(a->path, b->path);
 161 }
 162
 163 static void add_left_or_right(struct hashmap *map, const char *path,
 164                               const char *content, int is_right)
 165 {
 166         struct pair_entry *e, *existing;
 167
 168         FLEX_ALLOC_STR(e, path, path);
 169         hashmap_entry_init(&e->entry, strhash(path));
 170         existing = hashmap_get_entry(map, e, entry, NULL);
 171         if (existing) {
 172                 free(e);
 173                 e = existing;
 174         } else {
 175                 e->left[0] = e->right[0] = '\0';
 176                 hashmap_add(map, &e->entry);
 177         }
 178         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
 179 }
 180
 181 struct path_entry {
 182         struct hashmap_entry entry;
 183         char path[FLEX_ARRAY];
 184 };
 185
 186 static int path_entry_cmp(const void *unused_cmp_data,
 187                           const struct hashmap_entry *eptr,
 188                           const struct hashmap_entry *entry_or_key,
 189                           const void *key)
 190 {
 191         const struct path_entry *a, *b;
 192
 193         a = container_of(eptr, const struct path_entry, entry);
 194         b = container_of(entry_or_key, const struct path_entry, entry);
 195
 196         return strcmp(a->path, key ? key : b->path);
 197 }
 198
 199 static void changed_files(struct hashmap *result, const char *index_path,
 200                           const char *workdir)
 201 {
 202         struct child_process update_index = CHILD_PROCESS_INIT;
 203         struct child_process diff_files = CHILD_PROCESS_INIT;
 204         struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
 205         const char *git_dir = absolute_path(get_git_dir()), *env[] = {
 206                 NULL, NULL
 207         };
 208         FILE *fp;
 209
 210         strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
 211         env[0] = index_env.buf;
 212
 213         strvec_pushl(&update_index.args,
 214                      "--git-dir", git_dir, "--work-tree", workdir,
 215                      "update-index", "--really-refresh", "-q",
 216                      "--unmerged", NULL);
 217         update_index.no_stdin = 1;
 218         update_index.no_stdout = 1;
 219         update_index.no_stderr = 1;
 220         update_index.git_cmd = 1;
 221         update_index.use_shell = 0;
 222         update_index.clean_on_exit = 1;
 223         update_index.dir = workdir;
 224         update_index.env = env;
 225         /* Ignore any errors of update-index */
 226         run_command(&update_index);
 227
 228         strvec_pushl(&diff_files.args,
 229                      "--git-dir", git_dir, "--work-tree", workdir,
 230                      "diff-files", "--name-only", "-z", NULL);
 231         diff_files.no_stdin = 1;
 232         diff_files.git_cmd = 1;
 233         diff_files.use_shell = 0;
 234         diff_files.clean_on_exit = 1;
 235         diff_files.out = -1;
 236         diff_files.dir = workdir;
 237         diff_files.env = env;
 238         if (start_command(&diff_files))
 239                 die("could not obtain raw diff");
 240         fp = xfdopen(diff_files.out, "r");
 241         while (!strbuf_getline_nul(&buf, fp)) {
 242                 struct path_entry *entry;
 243                 FLEX_ALLOC_STR(entry, path, buf.buf);
 244                 hashmap_entry_init(&entry->entry, strhash(buf.buf));
 245                 hashmap_add(result, &entry->entry);
 246         }
 247         fclose(fp);
 248         if (finish_command(&diff_files))
 249                 die("diff-files did not exit properly");
 250         strbuf_release(&index_env);
 251         strbuf_release(&buf);
 252 }
 253
 254 static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
 255 {
 256         struct strbuf buf = STRBUF_INIT;
 257         strbuf_addstr(&buf, tmpdir);
 258         remove_dir_recursively(&buf, 0);
 259         if (exit_code)
 260                 warning(_("failed: %d"), exit_code);
 261         exit(exit_code);
 262 }
 263
 264 static int ensure_leading_directories(char *path)
 265 {
 266         switch (safe_create_leading_directories(path)) {
 267                 case SCLD_OK:
 268                 case SCLD_EXISTS:
 269                         return 0;
 270                 default:
 271                         return error(_("could not create leading directories "
 272                                        "of '%s'"), path);
 273         }
 274 }
 275
 276 /*
 277  * Unconditional writing of a plain regular file is what
 278  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 279  * temporary directories to be fed to a Git-unaware tool that knows how to
 280  * show a diff of two directories (e.g. "diff -r A B").
 281  *
 282  * Because the tool is Git-unaware, if a symbolic link appears in either of
 283  * these temporary directories, it will try to dereference and show the
 284  * difference of the target of the symbolic link, which is not what we want,
 285  * as the goal of the dir-diff mode is to produce an output that is logically
 286  * equivalent to what "git diff" produces.
 287  *
 288  * Most importantly, we want to get textual comparison of the result of the
 289  * readlink(2).  get_symlink() provides that---it returns the contents of
 290  * the symlink that gets written to a regular file to force the external tool
 291  * to compare the readlink(2) result as text, even on a filesystem that is
 292  * capable of doing a symbolic link.
 293  */
 294 static char *get_symlink(const struct object_id *oid, const char *path)
 295 {
 296         char *data;
 297         if (is_null_oid(oid)) {
 298                 /* The symlink is unknown to Git so read from the filesystem */
 299                 struct strbuf link = STRBUF_INIT;
 300                 if (has_symlinks) {
 301                         if (strbuf_readlink(&link, path, strlen(path)))
 302                                 die(_("could not read symlink %s"), path);
 303                 } else if (strbuf_read_file(&link, path, 128))
 304                         die(_("could not read symlink file %s"), path);
 305
 306                 data = strbuf_detach(&link, NULL);
 307         } else {
 308                 enum object_type type;
 309                 unsigned long size;
 310                 data = read_object_file(oid, &type, &size);
 311                 if (!data)
 312                         die(_("could not read object %s for symlink %s"),
 313                                 oid_to_hex(oid), path);
 314         }
 315
 316         return data;
 317 }
 318
 319 static int checkout_path(unsigned mode, struct object_id *oid,
 320                          const char *path, const struct checkout *state)
 321 {
 322         struct cache_entry *ce;
 323         int ret;
 324
 325         ce = make_transient_cache_entry(mode, oid, path, 0);
 326         ret = checkout_entry(ce, state, NULL, NULL);
 327
 328         discard_cache_entry(ce);
 329         return ret;
 330 }
 331
 332 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 333                         int argc, const char **argv)
 334 {
 335         char tmpdir[PATH_MAX];
 336         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 337         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 338         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 339         struct strbuf wtdir = STRBUF_INIT;
 340         char *lbase_dir, *rbase_dir;
 341         size_t ldir_len, rdir_len, wtdir_len;
 342         const char *workdir, *tmp;
 343         int ret = 0, i;
 344         FILE *fp;
 345         struct hashmap working_tree_dups = HASHMAP_INIT(working_tree_entry_cmp,
 346                                                         NULL);
 347         struct hashmap submodules = HASHMAP_INIT(pair_cmp, NULL);
 348         struct hashmap symlinks2 = HASHMAP_INIT(pair_cmp, NULL);
 349         struct hashmap_iter iter;
 350         struct pair_entry *entry;
 351         struct index_state wtindex;
 352         struct checkout lstate, rstate;
 353         int rc, flags = RUN_GIT_CMD, err = 0;
 354         struct child_process child = CHILD_PROCESS_INIT;
 355         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
 356         struct hashmap wt_modified, tmp_modified;
 357         int indices_loaded = 0;
 358
 359         workdir = get_git_work_tree();
 360
 361         /* Setup temp directories */
 362         tmp = getenv("TMPDIR");
 363         xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
 364         if (!mkdtemp(tmpdir))
 365                 return error("could not create '%s'", tmpdir);
 366         strbuf_addf(&ldir, "%s/left/", tmpdir);
 367         strbuf_addf(&rdir, "%s/right/", tmpdir);
 368         strbuf_addstr(&wtdir, workdir);
 369         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 370                 strbuf_addch(&wtdir, '/');
 371         mkdir(ldir.buf, 0700);
 372         mkdir(rdir.buf, 0700);
 373
 374         memset(&wtindex, 0, sizeof(wtindex));
 375
 376         memset(&lstate, 0, sizeof(lstate));
 377         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 378         lstate.base_dir_len = ldir.len;
 379         lstate.force = 1;
 380         memset(&rstate, 0, sizeof(rstate));
 381         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 382         rstate.base_dir_len = rdir.len;
 383         rstate.force = 1;
 384
 385         ldir_len = ldir.len;
 386         rdir_len = rdir.len;
 387         wtdir_len = wtdir.len;
 388
 389         child.no_stdin = 1;
 390         child.git_cmd = 1;
 391         child.use_shell = 0;
 392         child.clean_on_exit = 1;
 393         child.dir = prefix;
 394         child.out = -1;
 395         strvec_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
 396                      NULL);
 397         for (i = 0; i < argc; i++)
 398                 strvec_push(&child.args, argv[i]);
 399         if (start_command(&child))
 400                 die("could not obtain raw diff");
 401         fp = xfdopen(child.out, "r");
 402
 403         /* Build index info for left and right sides of the diff */
 404         i = 0;
 405         while (!strbuf_getline_nul(&info, fp)) {
 406                 int lmode, rmode;
 407                 struct object_id loid, roid;
 408                 char status;
 409                 const char *src_path, *dst_path;
 410
 411                 if (starts_with(info.buf, "::"))
 412                         die(N_("combined diff formats('-c' and '--cc') are "
 413                                "not supported in\n"
 414                                "directory diff mode('-d' and '--dir-diff')."));
 415
 416                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 417                                      &status))
 418                         break;
 419                 if (strbuf_getline_nul(&lpath, fp))
 420                         break;
 421                 src_path = lpath.buf;
 422
 423                 i++;
 424                 if (status != 'C' && status != 'R') {
 425                         dst_path = src_path;
 426                 } else {
 427                         if (strbuf_getline_nul(&rpath, fp))
 428                                 break;
 429                         dst_path = rpath.buf;
 430                 }
 431
 432                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 433                         strbuf_reset(&buf);
 434                         strbuf_addf(&buf, "Subproject commit %s",
 435                                     oid_to_hex(&loid));
 436                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 437                         strbuf_reset(&buf);
 438                         strbuf_addf(&buf, "Subproject commit %s",
 439                                     oid_to_hex(&roid));
 440                         if (oideq(&loid, &roid))
 441                                 strbuf_addstr(&buf, "-dirty");
 442                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 443                         continue;
 444                 }
 445
 446                 if (S_ISLNK(lmode)) {
 447                         char *content = get_symlink(&loid, src_path);
 448                         add_left_or_right(&symlinks2, src_path, content, 0);
 449                         free(content);
 450                 }
 451
 452                 if (S_ISLNK(rmode)) {
 453                         char *content = get_symlink(&roid, dst_path);
 454                         add_left_or_right(&symlinks2, dst_path, content, 1);
 455                         free(content);
 456                 }
 457
 458                 if (lmode && status != 'C') {
 459                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 460                                 ret = error("could not write '%s'", src_path);
 461                                 goto finish;
 462                         }
 463                 }
 464
 465                 if (rmode && !S_ISLNK(rmode)) {
 466                         struct working_tree_entry *entry;
 467
 468                         /* Avoid duplicate working_tree entries */
 469                         FLEX_ALLOC_STR(entry, path, dst_path);
 470                         hashmap_entry_init(&entry->entry, strhash(dst_path));
 471                         if (hashmap_get(&working_tree_dups, &entry->entry,
 472                                         NULL)) {
 473                                 free(entry);
 474                                 continue;
 475                         }
 476                         hashmap_add(&working_tree_dups, &entry->entry);
 477
 478                         if (!use_wt_file(workdir, dst_path, &roid)) {
 479                                 if (checkout_path(rmode, &roid, dst_path,
 480                                                   &rstate)) {
 481                                         ret = error("could not write '%s'",
 482                                                     dst_path);
 483                                         goto finish;
 484                                 }
 485                         } else if (!is_null_oid(&roid)) {
 486                                 /*
 487                                  * Changes in the working tree need special
 488                                  * treatment since they are not part of the
 489                                  * index.
 490                                  */
 491                                 struct cache_entry *ce2 =
 492                                         make_cache_entry(&wtindex, rmode, &roid,
 493                                                          dst_path, 0, 0);
 494
 495                                 add_index_entry(&wtindex, ce2,
 496                                                 ADD_CACHE_JUST_APPEND);
 497
 498                                 add_path(&rdir, rdir_len, dst_path);
 499                                 if (ensure_leading_directories(rdir.buf)) {
 500                                         ret = error("could not create "
 501                                                     "directory for '%s'",
 502                                                     dst_path);
 503                                         goto finish;
 504                                 }
 505                                 add_path(&wtdir, wtdir_len, dst_path);
 506                                 if (symlinks) {
 507                                         if (symlink(wtdir.buf, rdir.buf)) {
 508                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 509                                                 goto finish;
 510                                         }
 511                                 } else {
 512                                         struct stat st;
 513                                         if (stat(wtdir.buf, &st))
 514                                                 st.st_mode = 0644;
 515                                         if (copy_file(rdir.buf, wtdir.buf,
 516                                                       st.st_mode)) {
 517                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 518                                                 goto finish;
 519                                         }
 520                                 }
 521                         }
 522                 }
 523         }
 524
 525         fclose(fp);
 526         fp = NULL;
 527         if (finish_command(&child)) {
 528                 ret = error("error occurred running diff --raw");
 529                 goto finish;
 530         }
 531
 532         if (!i)
 533                 goto finish;
 534
 535         /*
 536          * Changes to submodules require special treatment.This loop writes a
 537          * temporary file to both the left and right directories to show the
 538          * change in the recorded SHA1 for the submodule.
 539          */
 540         hashmap_for_each_entry(&submodules, &iter, entry,
 541                                 entry /* member name */) {
 542                 if (*entry->left) {
 543                         add_path(&ldir, ldir_len, entry->path);
 544                         ensure_leading_directories(ldir.buf);
 545                         write_file(ldir.buf, "%s", entry->left);
 546                 }
 547                 if (*entry->right) {
 548                         add_path(&rdir, rdir_len, entry->path);
 549                         ensure_leading_directories(rdir.buf);
 550                         write_file(rdir.buf, "%s", entry->right);
 551                 }
 552         }
 553
 554         /*
 555          * Symbolic links require special treatment.The standard "git diff"
 556          * shows only the link itself, not the contents of the link target.
 557          * This loop replicates that behavior.
 558          */
 559         hashmap_for_each_entry(&symlinks2, &iter, entry,
 560                                 entry /* member name */) {
 561                 if (*entry->left) {
 562                         add_path(&ldir, ldir_len, entry->path);
 563                         ensure_leading_directories(ldir.buf);
 564                         write_file(ldir.buf, "%s", entry->left);
 565                 }
 566                 if (*entry->right) {
 567                         add_path(&rdir, rdir_len, entry->path);
 568                         ensure_leading_directories(rdir.buf);
 569                         write_file(rdir.buf, "%s", entry->right);
 570                 }
 571         }
 572
 573         strbuf_release(&buf);
 574
 575         strbuf_setlen(&ldir, ldir_len);
 576         helper_argv[1] = ldir.buf;
 577         strbuf_setlen(&rdir, rdir_len);
 578         helper_argv[2] = rdir.buf;
 579
 580         if (extcmd) {
 581                 helper_argv[0] = extcmd;
 582                 flags = 0;
 583         } else
 584                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 585         rc = run_command_v_opt(helper_argv, flags);
 586
 587         /*
 588          * If the diff includes working copy files and those
 589          * files were modified during the diff, then the changes
 590          * should be copied back to the working tree.
 591          * Do not copy back files when symlinks are used and the
 592          * external tool did not replace the original link with a file.
 593          *
 594          * These hashes are loaded lazily since they aren't needed
 595          * in the common case of --symlinks and the difftool updating
 596          * files through the symlink.
 597          */
 598         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 599         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 600
 601         for (i = 0; i < wtindex.cache_nr; i++) {
 602                 struct hashmap_entry dummy;
 603                 const char *name = wtindex.cache[i]->name;
 604                 struct stat st;
 605
 606                 add_path(&rdir, rdir_len, name);
 607                 if (lstat(rdir.buf, &st))
 608                         continue;
 609
 610                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 611                         continue;
 612
 613                 if (!indices_loaded) {
 614                         struct lock_file lock = LOCK_INIT;
 615                         strbuf_reset(&buf);
 616                         strbuf_addf(&buf, "%s/wtindex", tmpdir);
 617                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 618                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 619                                 ret = error("could not write %s", buf.buf);
 620                                 goto finish;
 621                         }
 622                         changed_files(&wt_modified, buf.buf, workdir);
 623                         strbuf_setlen(&rdir, rdir_len);
 624                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 625                         add_path(&rdir, rdir_len, name);
 626                         indices_loaded = 1;
 627                 }
 628
 629                 hashmap_entry_init(&dummy, strhash(name));
 630                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 631                         add_path(&wtdir, wtdir_len, name);
 632                         if (hashmap_get(&wt_modified, &dummy, name)) {
 633                                 warning(_("both files modified: '%s' and '%s'."),
 634                                         wtdir.buf, rdir.buf);
 635                                 warning(_("working tree file has been left."));
 636                                 warning("%s", "");
 637                                 err = 1;
 638                         } else if (unlink(wtdir.buf) ||
 639                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 640                                 warning_errno(_("could not copy '%s' to '%s'"),
 641                                               rdir.buf, wtdir.buf);
 642                 }
 643         }
 644
 645         if (err) {
 646                 warning(_("temporary files exist in '%s'."), tmpdir);
 647                 warning(_("you may want to cleanup or recover these."));
 648                 exit(1);
 649         } else
 650                 exit_cleanup(tmpdir, rc);
 651
 652 finish:
 653         if (fp)
 654                 fclose(fp);
 655
 656         free(lbase_dir);
 657         free(rbase_dir);
 658         strbuf_release(&ldir);
 659         strbuf_release(&rdir);
 660         strbuf_release(&wtdir);
 661         strbuf_release(&buf);
 662
 663         return ret;
 664 }
 665
 666 static int run_file_diff(int prompt, const char *prefix,
 667                          int argc, const char **argv)
 668 {
 669         struct strvec args = STRVEC_INIT;
 670         const char *env[] = {
 671                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 672                 NULL
 673         };
 674         int ret = 0, i;
 675
 676         if (prompt > 0)
 677                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 678         else if (!prompt)
 679                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 680
 681
 682         strvec_push(&args, "diff");
 683         for (i = 0; i < argc; i++)
 684                 strvec_push(&args, argv[i]);
 685         ret = run_command_v_opt_cd_env(args.v, RUN_GIT_CMD, prefix, env);
 686         exit(ret);
 687 }
 688
 689 int cmd_difftool(int argc, const char **argv, const char *prefix)
 690 {
 691         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 692             tool_help = 0, no_index = 0;
 693         static char *difftool_cmd = NULL, *extcmd = NULL;
 694         struct option builtin_difftool_options[] = {
 695                 OPT_BOOL('g', "gui", &use_gui_tool,
 696                          N_("use `diff.guitool` instead of `diff.tool`")),
 697                 OPT_BOOL('d', "dir-diff", &dir_diff,
 698                          N_("perform a full-directory diff")),
 699                 OPT_SET_INT_F('y', "no-prompt", &prompt,
 700                         N_("do not prompt before launching a diff tool"),
 701                         0, PARSE_OPT_NONEG),
 702                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
 703                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
 704                 OPT_BOOL(0, "symlinks", &symlinks,
 705                          N_("use symlinks in dir-diff mode")),
 706                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
 707                            N_("use the specified diff tool")),
 708                 OPT_BOOL(0, "tool-help", &tool_help,
 709                          N_("print a list of diff tools that may be used with "
 710                             "`--tool`")),
 711                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 712                          N_("make 'git-difftool' exit when an invoked diff "
 713                             "tool returns a non - zero exit code")),
 714                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 715                            N_("specify a custom command for viewing diffs")),
 716                 OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
 717                 OPT_END()
 718         };
 719
 720         git_config(difftool_config, NULL);
 721         symlinks = has_symlinks;
 722
 723         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 724                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
 725                              PARSE_OPT_KEEP_DASHDASH);
 726
 727         if (tool_help)
 728                 return print_tool_help();
 729
 730         if (!no_index && !startup_info->have_repository)
 731                 die(_("difftool requires worktree or --no-index"));
 732
 733         if (!no_index){
 734                 setup_work_tree();
 735                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 736                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 737         } else if (dir_diff)
 738                 die(_("--dir-diff is incompatible with --no-index"));
 739
 740         if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
 741                 die(_("--gui, --tool and --extcmd are mutually exclusive"));
 742
 743         if (use_gui_tool)
 744                 setenv("GIT_MERGETOOL_GUI", "true", 1);
 745         else if (difftool_cmd) {
 746                 if (*difftool_cmd)
 747                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 748                 else
 749                         die(_("no <tool> given for --tool=<tool>"));
 750         }
 751
 752         if (extcmd) {
 753                 if (*extcmd)
 754                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 755                 else
 756                         die(_("no <cmd> given for --extcmd=<cmd>"));
 757         }
 758
 759         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 760                trust_exit_code ? "true" : "false", 1);
 761
 762         /*
 763          * In directory diff mode, 'git-difftool--helper' is called once
 764          * to compare the a / b directories. In file diff mode, 'git diff'
 765          * will invoke a separate instance of 'git-difftool--helper' for
 766          * each file that changed.
 767          */
 768         if (dir_diff)
 769                 return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
 770         return run_file_diff(prompt, prefix, argc, argv);
 771 }