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