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_VARIABLE
  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         struct child_process cmd = CHILD_PROCESS_INIT;
  48
  49         cmd.git_cmd = 1;
  50         strvec_pushl(&cmd.args, "mergetool", "--tool-help=diff", NULL);
  51         return run_command(&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 (parse_oid_hex(++p, oid1, (const char **)&p))
  67                 return error("expected object ID, got '%s'", p);
  68         if (*p != ' ')
  69                 return error("expected ' ', got '%c'", *p);
  70         if (parse_oid_hex(++p, oid2, (const char **)&p))
  71                 return error("expected object ID, got '%s'", p);
  72         if (*p != ' ')
  73                 return error("expected ' ', got '%c'", *p);
  74         *status = *++p;
  75         if (!*status)
  76                 return error("missing status");
  77         if (p[1] && !isdigit(p[1]))
  78                 return error("unexpected trailer: '%s'", p + 1);
  79         return 0;
  80 }
  81
  82 /*
  83  * Remove any trailing slash from $workdir
  84  * before starting to avoid double slashes in symlink targets.
  85  */
  86 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
  87 {
  88         strbuf_setlen(buf, base_len);
  89         if (buf->len && buf->buf[buf->len - 1] != '/')
  90                 strbuf_addch(buf, '/');
  91         strbuf_addstr(buf, path);
  92 }
  93
  94 /*
  95  * Determine whether we can simply reuse the file in the worktree.
  96  */
  97 static int use_wt_file(const char *workdir, const char *name,
  98                        struct object_id *oid)
  99 {
 100         struct strbuf buf = STRBUF_INIT;
 101         struct stat st;
 102         int use = 0;
 103
 104         strbuf_addstr(&buf, workdir);
 105         add_path(&buf, buf.len, name);
 106
 107         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
 108                 struct object_id wt_oid;
 109                 int fd = open(buf.buf, O_RDONLY);
 110
 111                 if (fd >= 0 &&
 112                     !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
 113                         if (is_null_oid(oid)) {
 114                                 oidcpy(oid, &wt_oid);
 115                                 use = 1;
 116                         } else if (oideq(oid, &wt_oid))
 117                                 use = 1;
 118                 }
 119         }
 120
 121         strbuf_release(&buf);
 122
 123         return use;
 124 }
 125
 126 struct working_tree_entry {
 127         struct hashmap_entry entry;
 128         char path[FLEX_ARRAY];
 129 };
 130
 131 static int working_tree_entry_cmp(const void *cmp_data UNUSED,
 132                                   const struct hashmap_entry *eptr,
 133                                   const struct hashmap_entry *entry_or_key,
 134                                   const void *keydata UNUSED)
 135 {
 136         const struct working_tree_entry *a, *b;
 137
 138         a = container_of(eptr, const struct working_tree_entry, entry);
 139         b = container_of(entry_or_key, const struct working_tree_entry, entry);
 140
 141         return strcmp(a->path, b->path);
 142 }
 143
 144 /*
 145  * The `left` and `right` entries hold paths for the symlinks hashmap,
 146  * and a SHA-1 surrounded by brief text for submodules.
 147  */
 148 struct pair_entry {
 149         struct hashmap_entry entry;
 150         char left[PATH_MAX], right[PATH_MAX];
 151         const char path[FLEX_ARRAY];
 152 };
 153
 154 static int pair_cmp(const void *cmp_data UNUSED,
 155                     const struct hashmap_entry *eptr,
 156                     const struct hashmap_entry *entry_or_key,
 157                     const void *keydata UNUSED)
 158 {
 159         const struct pair_entry *a, *b;
 160
 161         a = container_of(eptr, const struct pair_entry, entry);
 162         b = container_of(entry_or_key, const struct pair_entry, entry);
 163
 164         return strcmp(a->path, b->path);
 165 }
 166
 167 static void add_left_or_right(struct hashmap *map, const char *path,
 168                               const char *content, int is_right)
 169 {
 170         struct pair_entry *e, *existing;
 171
 172         FLEX_ALLOC_STR(e, path, path);
 173         hashmap_entry_init(&e->entry, strhash(path));
 174         existing = hashmap_get_entry(map, e, entry, NULL);
 175         if (existing) {
 176                 free(e);
 177                 e = existing;
 178         } else {
 179                 e->left[0] = e->right[0] = '\0';
 180                 hashmap_add(map, &e->entry);
 181         }
 182         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
 183 }
 184
 185 struct path_entry {
 186         struct hashmap_entry entry;
 187         char path[FLEX_ARRAY];
 188 };
 189
 190 static int path_entry_cmp(const void *cmp_data UNUSED,
 191                           const struct hashmap_entry *eptr,
 192                           const struct hashmap_entry *entry_or_key,
 193                           const void *key)
 194 {
 195         const struct path_entry *a, *b;
 196
 197         a = container_of(eptr, const struct path_entry, entry);
 198         b = container_of(entry_or_key, const struct path_entry, entry);
 199
 200         return strcmp(a->path, key ? key : b->path);
 201 }
 202
 203 static void changed_files(struct hashmap *result, const char *index_path,
 204                           const char *workdir)
 205 {
 206         struct child_process update_index = CHILD_PROCESS_INIT;
 207         struct child_process diff_files = CHILD_PROCESS_INIT;
 208         struct strbuf buf = STRBUF_INIT;
 209         const char *git_dir = absolute_path(get_git_dir());
 210         FILE *fp;
 211
 212         strvec_pushl(&update_index.args,
 213                      "--git-dir", git_dir, "--work-tree", workdir,
 214                      "update-index", "--really-refresh", "-q",
 215                      "--unmerged", NULL);
 216         update_index.no_stdin = 1;
 217         update_index.no_stdout = 1;
 218         update_index.no_stderr = 1;
 219         update_index.git_cmd = 1;
 220         update_index.use_shell = 0;
 221         update_index.clean_on_exit = 1;
 222         update_index.dir = workdir;
 223         strvec_pushf(&update_index.env, "GIT_INDEX_FILE=%s", index_path);
 224         /* Ignore any errors of update-index */
 225         run_command(&update_index);
 226
 227         strvec_pushl(&diff_files.args,
 228                      "--git-dir", git_dir, "--work-tree", workdir,
 229                      "diff-files", "--name-only", "-z", NULL);
 230         diff_files.no_stdin = 1;
 231         diff_files.git_cmd = 1;
 232         diff_files.use_shell = 0;
 233         diff_files.clean_on_exit = 1;
 234         diff_files.out = -1;
 235         diff_files.dir = workdir;
 236         strvec_pushf(&diff_files.env, "GIT_INDEX_FILE=%s", index_path);
 237         if (start_command(&diff_files))
 238                 die("could not obtain raw diff");
 239         fp = xfdopen(diff_files.out, "r");
 240         while (!strbuf_getline_nul(&buf, fp)) {
 241                 struct path_entry *entry;
 242                 FLEX_ALLOC_STR(entry, path, buf.buf);
 243                 hashmap_entry_init(&entry->entry, strhash(buf.buf));
 244                 hashmap_add(result, &entry->entry);
 245         }
 246         fclose(fp);
 247         if (finish_command(&diff_files))
 248                 die("diff-files did not exit properly");
 249         strbuf_release(&buf);
 250 }
 251
 252 static int ensure_leading_directories(char *path)
 253 {
 254         switch (safe_create_leading_directories(path)) {
 255                 case SCLD_OK:
 256                 case SCLD_EXISTS:
 257                         return 0;
 258                 default:
 259                         return error(_("could not create leading directories "
 260                                        "of '%s'"), path);
 261         }
 262 }
 263
 264 /*
 265  * Unconditional writing of a plain regular file is what
 266  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 267  * temporary directories to be fed to a Git-unaware tool that knows how to
 268  * show a diff of two directories (e.g. "diff -r A B").
 269  *
 270  * Because the tool is Git-unaware, if a symbolic link appears in either of
 271  * these temporary directories, it will try to dereference and show the
 272  * difference of the target of the symbolic link, which is not what we want,
 273  * as the goal of the dir-diff mode is to produce an output that is logically
 274  * equivalent to what "git diff" produces.
 275  *
 276  * Most importantly, we want to get textual comparison of the result of the
 277  * readlink(2).  get_symlink() provides that---it returns the contents of
 278  * the symlink that gets written to a regular file to force the external tool
 279  * to compare the readlink(2) result as text, even on a filesystem that is
 280  * capable of doing a symbolic link.
 281  */
 282 static char *get_symlink(const struct object_id *oid, const char *path)
 283 {
 284         char *data;
 285         if (is_null_oid(oid)) {
 286                 /* The symlink is unknown to Git so read from the filesystem */
 287                 struct strbuf link = STRBUF_INIT;
 288                 if (has_symlinks) {
 289                         if (strbuf_readlink(&link, path, strlen(path)))
 290                                 die(_("could not read symlink %s"), path);
 291                 } else if (strbuf_read_file(&link, path, 128))
 292                         die(_("could not read symlink file %s"), path);
 293
 294                 data = strbuf_detach(&link, NULL);
 295         } else {
 296                 enum object_type type;
 297                 unsigned long size;
 298                 data = read_object_file(oid, &type, &size);
 299                 if (!data)
 300                         die(_("could not read object %s for symlink %s"),
 301                                 oid_to_hex(oid), path);
 302         }
 303
 304         return data;
 305 }
 306
 307 static int checkout_path(unsigned mode, struct object_id *oid,
 308                          const char *path, const struct checkout *state)
 309 {
 310         struct cache_entry *ce;
 311         int ret;
 312
 313         ce = make_transient_cache_entry(mode, oid, path, 0, NULL);
 314         ret = checkout_entry(ce, state, NULL, NULL);
 315
 316         discard_cache_entry(ce);
 317         return ret;
 318 }
 319
 320 static void write_file_in_directory(struct strbuf *dir, size_t dir_len,
 321                         const char *path, const char *content)
 322 {
 323         add_path(dir, dir_len, path);
 324         ensure_leading_directories(dir->buf);
 325         unlink(dir->buf);
 326         write_file(dir->buf, "%s", content);
 327 }
 328
 329 /* Write the file contents for the left and right sides of the difftool
 330  * dir-diff representation for submodules and symlinks. Symlinks and submodules
 331  * are written as regular text files so that external diff tools can diff them
 332  * as text files, resulting in behavior that is analogous to to what "git diff"
 333  * displays for symlink and submodule diffs.
 334  */
 335 static void write_standin_files(struct pair_entry *entry,
 336                         struct strbuf *ldir, size_t ldir_len,
 337                         struct strbuf *rdir, size_t rdir_len)
 338 {
 339         if (*entry->left)
 340                 write_file_in_directory(ldir, ldir_len, entry->path, entry->left);
 341         if (*entry->right)
 342                 write_file_in_directory(rdir, rdir_len, entry->path, entry->right);
 343 }
 344
 345 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 346                         struct child_process *child)
 347 {
 348         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 349         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 350         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 351         struct strbuf wtdir = STRBUF_INIT;
 352         struct strbuf tmpdir = STRBUF_INIT;
 353         char *lbase_dir = NULL, *rbase_dir = NULL;
 354         size_t ldir_len, rdir_len, wtdir_len;
 355         const char *workdir, *tmp;
 356         int ret = 0, i;
 357         FILE *fp = NULL;
 358         struct hashmap working_tree_dups = HASHMAP_INIT(working_tree_entry_cmp,
 359                                                         NULL);
 360         struct hashmap submodules = HASHMAP_INIT(pair_cmp, NULL);
 361         struct hashmap symlinks2 = HASHMAP_INIT(pair_cmp, NULL);
 362         struct hashmap_iter iter;
 363         struct pair_entry *entry;
 364         struct index_state wtindex;
 365         struct checkout lstate, rstate;
 366         int err = 0;
 367         struct child_process cmd = CHILD_PROCESS_INIT;
 368         struct hashmap wt_modified, tmp_modified;
 369         int indices_loaded = 0;
 370
 371         workdir = get_git_work_tree();
 372
 373         /* Setup temp directories */
 374         tmp = getenv("TMPDIR");
 375         strbuf_add_absolute_path(&tmpdir, tmp ? tmp : "/tmp");
 376         strbuf_trim_trailing_dir_sep(&tmpdir);
 377         strbuf_addstr(&tmpdir, "/git-difftool.XXXXXX");
 378         if (!mkdtemp(tmpdir.buf)) {
 379                 ret = error("could not create '%s'", tmpdir.buf);
 380                 goto finish;
 381         }
 382         strbuf_addf(&ldir, "%s/left/", tmpdir.buf);
 383         strbuf_addf(&rdir, "%s/right/", tmpdir.buf);
 384         strbuf_addstr(&wtdir, workdir);
 385         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 386                 strbuf_addch(&wtdir, '/');
 387         mkdir(ldir.buf, 0700);
 388         mkdir(rdir.buf, 0700);
 389
 390         memset(&wtindex, 0, sizeof(wtindex));
 391
 392         memset(&lstate, 0, sizeof(lstate));
 393         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 394         lstate.base_dir_len = ldir.len;
 395         lstate.force = 1;
 396         memset(&rstate, 0, sizeof(rstate));
 397         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 398         rstate.base_dir_len = rdir.len;
 399         rstate.force = 1;
 400
 401         ldir_len = ldir.len;
 402         rdir_len = rdir.len;
 403         wtdir_len = wtdir.len;
 404
 405         child->no_stdin = 1;
 406         child->git_cmd = 1;
 407         child->use_shell = 0;
 408         child->clean_on_exit = 1;
 409         child->dir = prefix;
 410         child->out = -1;
 411         if (start_command(child))
 412                 die("could not obtain raw diff");
 413         fp = xfdopen(child->out, "r");
 414
 415         /* Build index info for left and right sides of the diff */
 416         i = 0;
 417         while (!strbuf_getline_nul(&info, fp)) {
 418                 int lmode, rmode;
 419                 struct object_id loid, roid;
 420                 char status;
 421                 const char *src_path, *dst_path;
 422
 423                 if (starts_with(info.buf, "::"))
 424                         die(N_("combined diff formats ('-c' and '--cc') are "
 425                                "not supported in\n"
 426                                "directory diff mode ('-d' and '--dir-diff')."));
 427
 428                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 429                                      &status))
 430                         break;
 431                 if (strbuf_getline_nul(&lpath, fp))
 432                         break;
 433                 src_path = lpath.buf;
 434
 435                 i++;
 436                 if (status != 'C' && status != 'R') {
 437                         dst_path = src_path;
 438                 } else {
 439                         if (strbuf_getline_nul(&rpath, fp))
 440                                 break;
 441                         dst_path = rpath.buf;
 442                 }
 443
 444                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 445                         strbuf_reset(&buf);
 446                         strbuf_addf(&buf, "Subproject commit %s",
 447                                     oid_to_hex(&loid));
 448                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 449                         strbuf_reset(&buf);
 450                         strbuf_addf(&buf, "Subproject commit %s",
 451                                     oid_to_hex(&roid));
 452                         if (oideq(&loid, &roid))
 453                                 strbuf_addstr(&buf, "-dirty");
 454                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 455                         continue;
 456                 }
 457
 458                 if (S_ISLNK(lmode)) {
 459                         char *content = get_symlink(&loid, src_path);
 460                         add_left_or_right(&symlinks2, src_path, content, 0);
 461                         free(content);
 462                 }
 463
 464                 if (S_ISLNK(rmode)) {
 465                         char *content = get_symlink(&roid, dst_path);
 466                         add_left_or_right(&symlinks2, dst_path, content, 1);
 467                         free(content);
 468                 }
 469
 470                 if (lmode && status != 'C') {
 471                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 472                                 ret = error("could not write '%s'", src_path);
 473                                 goto finish;
 474                         }
 475                 }
 476
 477                 if (rmode && !S_ISLNK(rmode)) {
 478                         struct working_tree_entry *entry;
 479
 480                         /* Avoid duplicate working_tree entries */
 481                         FLEX_ALLOC_STR(entry, path, dst_path);
 482                         hashmap_entry_init(&entry->entry, strhash(dst_path));
 483                         if (hashmap_get(&working_tree_dups, &entry->entry,
 484                                         NULL)) {
 485                                 free(entry);
 486                                 continue;
 487                         }
 488                         hashmap_add(&working_tree_dups, &entry->entry);
 489
 490                         if (!use_wt_file(workdir, dst_path, &roid)) {
 491                                 if (checkout_path(rmode, &roid, dst_path,
 492                                                   &rstate)) {
 493                                         ret = error("could not write '%s'",
 494                                                     dst_path);
 495                                         goto finish;
 496                                 }
 497                         } else if (!is_null_oid(&roid)) {
 498                                 /*
 499                                  * Changes in the working tree need special
 500                                  * treatment since they are not part of the
 501                                  * index.
 502                                  */
 503                                 struct cache_entry *ce2 =
 504                                         make_cache_entry(&wtindex, rmode, &roid,
 505                                                          dst_path, 0, 0);
 506
 507                                 add_index_entry(&wtindex, ce2,
 508                                                 ADD_CACHE_JUST_APPEND);
 509
 510                                 add_path(&rdir, rdir_len, dst_path);
 511                                 if (ensure_leading_directories(rdir.buf)) {
 512                                         ret = error("could not create "
 513                                                     "directory for '%s'",
 514                                                     dst_path);
 515                                         goto finish;
 516                                 }
 517                                 add_path(&wtdir, wtdir_len, dst_path);
 518                                 if (symlinks) {
 519                                         if (symlink(wtdir.buf, rdir.buf)) {
 520                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 521                                                 goto finish;
 522                                         }
 523                                 } else {
 524                                         struct stat st;
 525                                         if (stat(wtdir.buf, &st))
 526                                                 st.st_mode = 0644;
 527                                         if (copy_file(rdir.buf, wtdir.buf,
 528                                                       st.st_mode)) {
 529                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 530                                                 goto finish;
 531                                         }
 532                                 }
 533                         }
 534                 }
 535         }
 536
 537         fclose(fp);
 538         fp = NULL;
 539         if (finish_command(child)) {
 540                 ret = error("error occurred running diff --raw");
 541                 goto finish;
 542         }
 543
 544         if (!i)
 545                 goto finish;
 546
 547         /*
 548          * Changes to submodules require special treatment.This loop writes a
 549          * temporary file to both the left and right directories to show the
 550          * change in the recorded SHA1 for the submodule.
 551          */
 552         hashmap_for_each_entry(&submodules, &iter, entry,
 553                                 entry /* member name */) {
 554                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 555         }
 556
 557         /*
 558          * Symbolic links require special treatment. The standard "git diff"
 559          * shows only the link itself, not the contents of the link target.
 560          * This loop replicates that behavior.
 561          */
 562         hashmap_for_each_entry(&symlinks2, &iter, entry,
 563                                 entry /* member name */) {
 564
 565                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 566         }
 567
 568         strbuf_setlen(&ldir, ldir_len);
 569         strbuf_setlen(&rdir, rdir_len);
 570
 571         if (extcmd) {
 572                 strvec_push(&cmd.args, extcmd);
 573         } else {
 574                 strvec_push(&cmd.args, "difftool--helper");
 575                 cmd.git_cmd = 1;
 576                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 577         }
 578         strvec_pushl(&cmd.args, ldir.buf, rdir.buf, NULL);
 579         ret = run_command(&cmd);
 580
 581         /* TODO: audit for interaction with sparse-index. */
 582         ensure_full_index(&wtindex);
 583
 584         /*
 585          * If the diff includes working copy files and those
 586          * files were modified during the diff, then the changes
 587          * should be copied back to the working tree.
 588          * Do not copy back files when symlinks are used and the
 589          * external tool did not replace the original link with a file.
 590          *
 591          * These hashes are loaded lazily since they aren't needed
 592          * in the common case of --symlinks and the difftool updating
 593          * files through the symlink.
 594          */
 595         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 596         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 597
 598         for (i = 0; i < wtindex.cache_nr; i++) {
 599                 struct hashmap_entry dummy;
 600                 const char *name = wtindex.cache[i]->name;
 601                 struct stat st;
 602
 603                 add_path(&rdir, rdir_len, name);
 604                 if (lstat(rdir.buf, &st))
 605                         continue;
 606
 607                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 608                         continue;
 609
 610                 if (!indices_loaded) {
 611                         struct lock_file lock = LOCK_INIT;
 612                         strbuf_reset(&buf);
 613                         strbuf_addf(&buf, "%s/wtindex", tmpdir.buf);
 614                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 615                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 616                                 ret = error("could not write %s", buf.buf);
 617                                 goto finish;
 618                         }
 619                         changed_files(&wt_modified, buf.buf, workdir);
 620                         strbuf_setlen(&rdir, rdir_len);
 621                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 622                         add_path(&rdir, rdir_len, name);
 623                         indices_loaded = 1;
 624                 }
 625
 626                 hashmap_entry_init(&dummy, strhash(name));
 627                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 628                         add_path(&wtdir, wtdir_len, name);
 629                         if (hashmap_get(&wt_modified, &dummy, name)) {
 630                                 warning(_("both files modified: '%s' and '%s'."),
 631                                         wtdir.buf, rdir.buf);
 632                                 warning(_("working tree file has been left."));
 633                                 warning("%s", "");
 634                                 err = 1;
 635                         } else if (unlink(wtdir.buf) ||
 636                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 637                                 warning_errno(_("could not copy '%s' to '%s'"),
 638                                               rdir.buf, wtdir.buf);
 639                 }
 640         }
 641
 642         if (err) {
 643                 warning(_("temporary files exist in '%s'."), tmpdir.buf);
 644                 warning(_("you may want to cleanup or recover these."));
 645                 ret = 1;
 646         } else {
 647                 remove_dir_recursively(&tmpdir, 0);
 648                 if (ret)
 649                         warning(_("failed: %d"), ret);
 650         }
 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         strbuf_release(&tmpdir);
 663
 664         return (ret < 0) ? 1 : ret;
 665 }
 666
 667 static int run_file_diff(int prompt, const char *prefix,
 668                          struct child_process *child)
 669 {
 670         const char *env[] = {
 671                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 672                 NULL
 673         };
 674
 675         if (prompt > 0)
 676                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 677         else if (!prompt)
 678                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 679
 680         child->git_cmd = 1;
 681         child->dir = prefix;
 682         strvec_pushv(&child->env, env);
 683
 684         return run_command(child);
 685 }
 686
 687 int cmd_difftool(int argc, const char **argv, const char *prefix)
 688 {
 689         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 690             tool_help = 0, no_index = 0;
 691         static char *difftool_cmd = NULL, *extcmd = NULL;
 692         struct option builtin_difftool_options[] = {
 693                 OPT_BOOL('g', "gui", &use_gui_tool,
 694                          N_("use `diff.guitool` instead of `diff.tool`")),
 695                 OPT_BOOL('d', "dir-diff", &dir_diff,
 696                          N_("perform a full-directory diff")),
 697                 OPT_SET_INT_F('y', "no-prompt", &prompt,
 698                         N_("do not prompt before launching a diff tool"),
 699                         0, PARSE_OPT_NONEG),
 700                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
 701                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
 702                 OPT_BOOL(0, "symlinks", &symlinks,
 703                          N_("use symlinks in dir-diff mode")),
 704                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
 705                            N_("use the specified diff tool")),
 706                 OPT_BOOL(0, "tool-help", &tool_help,
 707                          N_("print a list of diff tools that may be used with "
 708                             "`--tool`")),
 709                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 710                          N_("make 'git-difftool' exit when an invoked diff "
 711                             "tool returns a non-zero exit code")),
 712                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 713                            N_("specify a custom command for viewing diffs")),
 714                 OPT_BOOL(0, "no-index", &no_index, N_("passed to `diff`")),
 715                 OPT_END()
 716         };
 717         struct child_process child = CHILD_PROCESS_INIT;
 718
 719         git_config(difftool_config, NULL);
 720         symlinks = has_symlinks;
 721
 722         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 723                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN_OPT |
 724                              PARSE_OPT_KEEP_DASHDASH);
 725
 726         if (tool_help)
 727                 return print_tool_help();
 728
 729         if (!no_index && !startup_info->have_repository)
 730                 die(_("difftool requires worktree or --no-index"));
 731
 732         if (!no_index){
 733                 setup_work_tree();
 734                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 735                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 736         } else if (dir_diff)
 737                 die(_("options '%s' and '%s' cannot be used together"), "--dir-diff", "--no-index");
 738
 739         die_for_incompatible_opt3(use_gui_tool, "--gui",
 740                                   !!difftool_cmd, "--tool",
 741                                   !!extcmd, "--extcmd");
 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         strvec_push(&child.args, "diff");
 769         if (no_index)
 770                 strvec_push(&child.args, "--no-index");
 771         if (dir_diff)
 772                 strvec_pushl(&child.args, "--raw", "--no-abbrev", "-z", NULL);
 773         strvec_pushv(&child.args, argv);
 774
 775         if (dir_diff)
 776                 return run_dir_diff(extcmd, symlinks, prefix, &child);
 777         return run_file_diff(prompt, prefix, &child);
 778 }