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 buf = STRBUF_INIT;
 206         const char *git_dir = absolute_path(get_git_dir());
 207         FILE *fp;
 208
 209         strvec_pushl(&update_index.args,
 210                      "--git-dir", git_dir, "--work-tree", workdir,
 211                      "update-index", "--really-refresh", "-q",
 212                      "--unmerged", NULL);
 213         update_index.no_stdin = 1;
 214         update_index.no_stdout = 1;
 215         update_index.no_stderr = 1;
 216         update_index.git_cmd = 1;
 217         update_index.use_shell = 0;
 218         update_index.clean_on_exit = 1;
 219         update_index.dir = workdir;
 220         strvec_pushf(&update_index.env_array, "GIT_INDEX_FILE=%s", index_path);
 221         /* Ignore any errors of update-index */
 222         run_command(&update_index);
 223
 224         strvec_pushl(&diff_files.args,
 225                      "--git-dir", git_dir, "--work-tree", workdir,
 226                      "diff-files", "--name-only", "-z", NULL);
 227         diff_files.no_stdin = 1;
 228         diff_files.git_cmd = 1;
 229         diff_files.use_shell = 0;
 230         diff_files.clean_on_exit = 1;
 231         diff_files.out = -1;
 232         diff_files.dir = workdir;
 233         strvec_pushf(&diff_files.env_array, "GIT_INDEX_FILE=%s", index_path);
 234         if (start_command(&diff_files))
 235                 die("could not obtain raw diff");
 236         fp = xfdopen(diff_files.out, "r");
 237         while (!strbuf_getline_nul(&buf, fp)) {
 238                 struct path_entry *entry;
 239                 FLEX_ALLOC_STR(entry, path, buf.buf);
 240                 hashmap_entry_init(&entry->entry, strhash(buf.buf));
 241                 hashmap_add(result, &entry->entry);
 242         }
 243         fclose(fp);
 244         if (finish_command(&diff_files))
 245                 die("diff-files did not exit properly");
 246         strbuf_release(&buf);
 247 }
 248
 249 static int ensure_leading_directories(char *path)
 250 {
 251         switch (safe_create_leading_directories(path)) {
 252                 case SCLD_OK:
 253                 case SCLD_EXISTS:
 254                         return 0;
 255                 default:
 256                         return error(_("could not create leading directories "
 257                                        "of '%s'"), path);
 258         }
 259 }
 260
 261 /*
 262  * Unconditional writing of a plain regular file is what
 263  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 264  * temporary directories to be fed to a Git-unaware tool that knows how to
 265  * show a diff of two directories (e.g. "diff -r A B").
 266  *
 267  * Because the tool is Git-unaware, if a symbolic link appears in either of
 268  * these temporary directories, it will try to dereference and show the
 269  * difference of the target of the symbolic link, which is not what we want,
 270  * as the goal of the dir-diff mode is to produce an output that is logically
 271  * equivalent to what "git diff" produces.
 272  *
 273  * Most importantly, we want to get textual comparison of the result of the
 274  * readlink(2).  get_symlink() provides that---it returns the contents of
 275  * the symlink that gets written to a regular file to force the external tool
 276  * to compare the readlink(2) result as text, even on a filesystem that is
 277  * capable of doing a symbolic link.
 278  */
 279 static char *get_symlink(const struct object_id *oid, const char *path)
 280 {
 281         char *data;
 282         if (is_null_oid(oid)) {
 283                 /* The symlink is unknown to Git so read from the filesystem */
 284                 struct strbuf link = STRBUF_INIT;
 285                 if (has_symlinks) {
 286                         if (strbuf_readlink(&link, path, strlen(path)))
 287                                 die(_("could not read symlink %s"), path);
 288                 } else if (strbuf_read_file(&link, path, 128))
 289                         die(_("could not read symlink file %s"), path);
 290
 291                 data = strbuf_detach(&link, NULL);
 292         } else {
 293                 enum object_type type;
 294                 unsigned long size;
 295                 data = read_object_file(oid, &type, &size);
 296                 if (!data)
 297                         die(_("could not read object %s for symlink %s"),
 298                                 oid_to_hex(oid), path);
 299         }
 300
 301         return data;
 302 }
 303
 304 static int checkout_path(unsigned mode, struct object_id *oid,
 305                          const char *path, const struct checkout *state)
 306 {
 307         struct cache_entry *ce;
 308         int ret;
 309
 310         ce = make_transient_cache_entry(mode, oid, path, 0, NULL);
 311         ret = checkout_entry(ce, state, NULL, NULL);
 312
 313         discard_cache_entry(ce);
 314         return ret;
 315 }
 316
 317 static void write_file_in_directory(struct strbuf *dir, size_t dir_len,
 318                         const char *path, const char *content)
 319 {
 320         add_path(dir, dir_len, path);
 321         ensure_leading_directories(dir->buf);
 322         unlink(dir->buf);
 323         write_file(dir->buf, "%s", content);
 324 }
 325
 326 /* Write the file contents for the left and right sides of the difftool
 327  * dir-diff representation for submodules and symlinks. Symlinks and submodules
 328  * are written as regular text files so that external diff tools can diff them
 329  * as text files, resulting in behavior that is analogous to to what "git diff"
 330  * displays for symlink and submodule diffs.
 331  */
 332 static void write_standin_files(struct pair_entry *entry,
 333                         struct strbuf *ldir, size_t ldir_len,
 334                         struct strbuf *rdir, size_t rdir_len)
 335 {
 336         if (*entry->left)
 337                 write_file_in_directory(ldir, ldir_len, entry->path, entry->left);
 338         if (*entry->right)
 339                 write_file_in_directory(rdir, rdir_len, entry->path, entry->right);
 340 }
 341
 342 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 343                         struct child_process *child)
 344 {
 345         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 346         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 347         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 348         struct strbuf wtdir = STRBUF_INIT;
 349         struct strbuf tmpdir = STRBUF_INIT;
 350         char *lbase_dir = NULL, *rbase_dir = NULL;
 351         size_t ldir_len, rdir_len, wtdir_len;
 352         const char *workdir, *tmp;
 353         int ret = 0, i;
 354         FILE *fp = NULL;
 355         struct hashmap working_tree_dups = HASHMAP_INIT(working_tree_entry_cmp,
 356                                                         NULL);
 357         struct hashmap submodules = HASHMAP_INIT(pair_cmp, NULL);
 358         struct hashmap symlinks2 = HASHMAP_INIT(pair_cmp, NULL);
 359         struct hashmap_iter iter;
 360         struct pair_entry *entry;
 361         struct index_state wtindex;
 362         struct checkout lstate, rstate;
 363         int flags = RUN_GIT_CMD, err = 0;
 364         const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
 365         struct hashmap wt_modified, tmp_modified;
 366         int indices_loaded = 0;
 367
 368         workdir = get_git_work_tree();
 369
 370         /* Setup temp directories */
 371         tmp = getenv("TMPDIR");
 372         strbuf_add_absolute_path(&tmpdir, tmp ? tmp : "/tmp");
 373         strbuf_trim_trailing_dir_sep(&tmpdir);
 374         strbuf_addstr(&tmpdir, "/git-difftool.XXXXXX");
 375         if (!mkdtemp(tmpdir.buf)) {
 376                 ret = error("could not create '%s'", tmpdir.buf);
 377                 goto finish;
 378         }
 379         strbuf_addf(&ldir, "%s/left/", tmpdir.buf);
 380         strbuf_addf(&rdir, "%s/right/", tmpdir.buf);
 381         strbuf_addstr(&wtdir, workdir);
 382         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 383                 strbuf_addch(&wtdir, '/');
 384         mkdir(ldir.buf, 0700);
 385         mkdir(rdir.buf, 0700);
 386
 387         memset(&wtindex, 0, sizeof(wtindex));
 388
 389         memset(&lstate, 0, sizeof(lstate));
 390         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 391         lstate.base_dir_len = ldir.len;
 392         lstate.force = 1;
 393         memset(&rstate, 0, sizeof(rstate));
 394         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 395         rstate.base_dir_len = rdir.len;
 396         rstate.force = 1;
 397
 398         ldir_len = ldir.len;
 399         rdir_len = rdir.len;
 400         wtdir_len = wtdir.len;
 401
 402         child->no_stdin = 1;
 403         child->git_cmd = 1;
 404         child->use_shell = 0;
 405         child->clean_on_exit = 1;
 406         child->dir = prefix;
 407         child->out = -1;
 408         if (start_command(child))
 409                 die("could not obtain raw diff");
 410         fp = xfdopen(child->out, "r");
 411
 412         /* Build index info for left and right sides of the diff */
 413         i = 0;
 414         while (!strbuf_getline_nul(&info, fp)) {
 415                 int lmode, rmode;
 416                 struct object_id loid, roid;
 417                 char status;
 418                 const char *src_path, *dst_path;
 419
 420                 if (starts_with(info.buf, "::"))
 421                         die(N_("combined diff formats ('-c' and '--cc') are "
 422                                "not supported in\n"
 423                                "directory diff mode ('-d' and '--dir-diff')."));
 424
 425                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 426                                      &status))
 427                         break;
 428                 if (strbuf_getline_nul(&lpath, fp))
 429                         break;
 430                 src_path = lpath.buf;
 431
 432                 i++;
 433                 if (status != 'C' && status != 'R') {
 434                         dst_path = src_path;
 435                 } else {
 436                         if (strbuf_getline_nul(&rpath, fp))
 437                                 break;
 438                         dst_path = rpath.buf;
 439                 }
 440
 441                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 442                         strbuf_reset(&buf);
 443                         strbuf_addf(&buf, "Subproject commit %s",
 444                                     oid_to_hex(&loid));
 445                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 446                         strbuf_reset(&buf);
 447                         strbuf_addf(&buf, "Subproject commit %s",
 448                                     oid_to_hex(&roid));
 449                         if (oideq(&loid, &roid))
 450                                 strbuf_addstr(&buf, "-dirty");
 451                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 452                         continue;
 453                 }
 454
 455                 if (S_ISLNK(lmode)) {
 456                         char *content = get_symlink(&loid, src_path);
 457                         add_left_or_right(&symlinks2, src_path, content, 0);
 458                         free(content);
 459                 }
 460
 461                 if (S_ISLNK(rmode)) {
 462                         char *content = get_symlink(&roid, dst_path);
 463                         add_left_or_right(&symlinks2, dst_path, content, 1);
 464                         free(content);
 465                 }
 466
 467                 if (lmode && status != 'C') {
 468                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 469                                 ret = error("could not write '%s'", src_path);
 470                                 goto finish;
 471                         }
 472                 }
 473
 474                 if (rmode && !S_ISLNK(rmode)) {
 475                         struct working_tree_entry *entry;
 476
 477                         /* Avoid duplicate working_tree entries */
 478                         FLEX_ALLOC_STR(entry, path, dst_path);
 479                         hashmap_entry_init(&entry->entry, strhash(dst_path));
 480                         if (hashmap_get(&working_tree_dups, &entry->entry,
 481                                         NULL)) {
 482                                 free(entry);
 483                                 continue;
 484                         }
 485                         hashmap_add(&working_tree_dups, &entry->entry);
 486
 487                         if (!use_wt_file(workdir, dst_path, &roid)) {
 488                                 if (checkout_path(rmode, &roid, dst_path,
 489                                                   &rstate)) {
 490                                         ret = error("could not write '%s'",
 491                                                     dst_path);
 492                                         goto finish;
 493                                 }
 494                         } else if (!is_null_oid(&roid)) {
 495                                 /*
 496                                  * Changes in the working tree need special
 497                                  * treatment since they are not part of the
 498                                  * index.
 499                                  */
 500                                 struct cache_entry *ce2 =
 501                                         make_cache_entry(&wtindex, rmode, &roid,
 502                                                          dst_path, 0, 0);
 503
 504                                 add_index_entry(&wtindex, ce2,
 505                                                 ADD_CACHE_JUST_APPEND);
 506
 507                                 add_path(&rdir, rdir_len, dst_path);
 508                                 if (ensure_leading_directories(rdir.buf)) {
 509                                         ret = error("could not create "
 510                                                     "directory for '%s'",
 511                                                     dst_path);
 512                                         goto finish;
 513                                 }
 514                                 add_path(&wtdir, wtdir_len, dst_path);
 515                                 if (symlinks) {
 516                                         if (symlink(wtdir.buf, rdir.buf)) {
 517                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 518                                                 goto finish;
 519                                         }
 520                                 } else {
 521                                         struct stat st;
 522                                         if (stat(wtdir.buf, &st))
 523                                                 st.st_mode = 0644;
 524                                         if (copy_file(rdir.buf, wtdir.buf,
 525                                                       st.st_mode)) {
 526                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 527                                                 goto finish;
 528                                         }
 529                                 }
 530                         }
 531                 }
 532         }
 533
 534         fclose(fp);
 535         fp = NULL;
 536         if (finish_command(child)) {
 537                 ret = error("error occurred running diff --raw");
 538                 goto finish;
 539         }
 540
 541         if (!i)
 542                 goto finish;
 543
 544         /*
 545          * Changes to submodules require special treatment.This loop writes a
 546          * temporary file to both the left and right directories to show the
 547          * change in the recorded SHA1 for the submodule.
 548          */
 549         hashmap_for_each_entry(&submodules, &iter, entry,
 550                                 entry /* member name */) {
 551                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 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
 562                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 563         }
 564
 565         strbuf_setlen(&ldir, ldir_len);
 566         helper_argv[1] = ldir.buf;
 567         strbuf_setlen(&rdir, rdir_len);
 568         helper_argv[2] = rdir.buf;
 569
 570         if (extcmd) {
 571                 helper_argv[0] = extcmd;
 572                 flags = 0;
 573         } else
 574                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 575         ret = run_command_v_opt(helper_argv, flags);
 576
 577         /* TODO: audit for interaction with sparse-index. */
 578         ensure_full_index(&wtindex);
 579
 580         /*
 581          * If the diff includes working copy files and those
 582          * files were modified during the diff, then the changes
 583          * should be copied back to the working tree.
 584          * Do not copy back files when symlinks are used and the
 585          * external tool did not replace the original link with a file.
 586          *
 587          * These hashes are loaded lazily since they aren't needed
 588          * in the common case of --symlinks and the difftool updating
 589          * files through the symlink.
 590          */
 591         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 592         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 593
 594         for (i = 0; i < wtindex.cache_nr; i++) {
 595                 struct hashmap_entry dummy;
 596                 const char *name = wtindex.cache[i]->name;
 597                 struct stat st;
 598
 599                 add_path(&rdir, rdir_len, name);
 600                 if (lstat(rdir.buf, &st))
 601                         continue;
 602
 603                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 604                         continue;
 605
 606                 if (!indices_loaded) {
 607                         struct lock_file lock = LOCK_INIT;
 608                         strbuf_reset(&buf);
 609                         strbuf_addf(&buf, "%s/wtindex", tmpdir.buf);
 610                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 611                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 612                                 ret = error("could not write %s", buf.buf);
 613                                 goto finish;
 614                         }
 615                         changed_files(&wt_modified, buf.buf, workdir);
 616                         strbuf_setlen(&rdir, rdir_len);
 617                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 618                         add_path(&rdir, rdir_len, name);
 619                         indices_loaded = 1;
 620                 }
 621
 622                 hashmap_entry_init(&dummy, strhash(name));
 623                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 624                         add_path(&wtdir, wtdir_len, name);
 625                         if (hashmap_get(&wt_modified, &dummy, name)) {
 626                                 warning(_("both files modified: '%s' and '%s'."),
 627                                         wtdir.buf, rdir.buf);
 628                                 warning(_("working tree file has been left."));
 629                                 warning("%s", "");
 630                                 err = 1;
 631                         } else if (unlink(wtdir.buf) ||
 632                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 633                                 warning_errno(_("could not copy '%s' to '%s'"),
 634                                               rdir.buf, wtdir.buf);
 635                 }
 636         }
 637
 638         if (err) {
 639                 warning(_("temporary files exist in '%s'."), tmpdir.buf);
 640                 warning(_("you may want to cleanup or recover these."));
 641                 ret = 1;
 642         } else {
 643                 remove_dir_recursively(&tmpdir, 0);
 644                 if (ret)
 645                         warning(_("failed: %d"), ret);
 646         }
 647
 648 finish:
 649         if (fp)
 650                 fclose(fp);
 651
 652         free(lbase_dir);
 653         free(rbase_dir);
 654         strbuf_release(&ldir);
 655         strbuf_release(&rdir);
 656         strbuf_release(&wtdir);
 657         strbuf_release(&buf);
 658         strbuf_release(&tmpdir);
 659
 660         return (ret < 0) ? 1 : ret;
 661 }
 662
 663 static int run_file_diff(int prompt, const char *prefix,
 664                          struct child_process *child)
 665 {
 666         const char *env[] = {
 667                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 668                 NULL
 669         };
 670
 671         if (prompt > 0)
 672                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 673         else if (!prompt)
 674                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 675
 676         child->git_cmd = 1;
 677         child->dir = prefix;
 678         strvec_pushv(&child->env_array, env);
 679
 680         return run_command(child);
 681 }
 682
 683 int cmd_difftool(int argc, const char **argv, const char *prefix)
 684 {
 685         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 686             tool_help = 0, no_index = 0;
 687         static char *difftool_cmd = NULL, *extcmd = NULL;
 688         struct option builtin_difftool_options[] = {
 689                 OPT_BOOL('g', "gui", &use_gui_tool,
 690                          N_("use `diff.guitool` instead of `diff.tool`")),
 691                 OPT_BOOL('d', "dir-diff", &dir_diff,
 692                          N_("perform a full-directory diff")),
 693                 OPT_SET_INT_F('y', "no-prompt", &prompt,
 694                         N_("do not prompt before launching a diff tool"),
 695                         0, PARSE_OPT_NONEG),
 696                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
 697                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
 698                 OPT_BOOL(0, "symlinks", &symlinks,
 699                          N_("use symlinks in dir-diff mode")),
 700                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
 701                            N_("use the specified diff tool")),
 702                 OPT_BOOL(0, "tool-help", &tool_help,
 703                          N_("print a list of diff tools that may be used with "
 704                             "`--tool`")),
 705                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 706                          N_("make 'git-difftool' exit when an invoked diff "
 707                             "tool returns a non-zero exit code")),
 708                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 709                            N_("specify a custom command for viewing diffs")),
 710                 OPT_BOOL(0, "no-index", &no_index, N_("passed to `diff`")),
 711                 OPT_END()
 712         };
 713         struct child_process child = CHILD_PROCESS_INIT;
 714
 715         git_config(difftool_config, NULL);
 716         symlinks = has_symlinks;
 717
 718         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 719                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
 720                              PARSE_OPT_KEEP_DASHDASH);
 721
 722         if (tool_help)
 723                 return print_tool_help();
 724
 725         if (!no_index && !startup_info->have_repository)
 726                 die(_("difftool requires worktree or --no-index"));
 727
 728         if (!no_index){
 729                 setup_work_tree();
 730                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 731                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 732         } else if (dir_diff)
 733                 die(_("--dir-diff is incompatible with --no-index"));
 734
 735         if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
 736                 die(_("options '%s', '%s', and '%s' cannot be used together"), "--gui", "--tool", "--extcmd");
 737
 738         if (use_gui_tool)
 739                 setenv("GIT_MERGETOOL_GUI", "true", 1);
 740         else if (difftool_cmd) {
 741                 if (*difftool_cmd)
 742                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 743                 else
 744                         die(_("no <tool> given for --tool=<tool>"));
 745         }
 746
 747         if (extcmd) {
 748                 if (*extcmd)
 749                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 750                 else
 751                         die(_("no <cmd> given for --extcmd=<cmd>"));
 752         }
 753
 754         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 755                trust_exit_code ? "true" : "false", 1);
 756
 757         /*
 758          * In directory diff mode, 'git-difftool--helper' is called once
 759          * to compare the a / b directories. In file diff mode, 'git diff'
 760          * will invoke a separate instance of 'git-difftool--helper' for
 761          * each file that changed.
 762          */
 763         strvec_push(&child.args, "diff");
 764         if (no_index)
 765                 strvec_push(&child.args, "--no-index");
 766         if (dir_diff)
 767                 strvec_pushl(&child.args, "--raw", "--no-abbrev", "-z", NULL);
 768         strvec_pushv(&child.args, argv);
 769
 770         if (dir_diff)
 771                 return run_dir_diff(extcmd, symlinks, prefix, &child);
 772         return run_file_diff(prompt, prefix, &child);
 773 }