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 = INDEX_STATE_INIT(the_repository);
 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(&lstate, 0, sizeof(lstate));
 391         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 392         lstate.base_dir_len = ldir.len;
 393         lstate.force = 1;
 394         memset(&rstate, 0, sizeof(rstate));
 395         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 396         rstate.base_dir_len = rdir.len;
 397         rstate.force = 1;
 398
 399         ldir_len = ldir.len;
 400         rdir_len = rdir.len;
 401         wtdir_len = wtdir.len;
 402
 403         child->no_stdin = 1;
 404         child->git_cmd = 1;
 405         child->use_shell = 0;
 406         child->clean_on_exit = 1;
 407         child->dir = prefix;
 408         child->out = -1;
 409         if (start_command(child))
 410                 die("could not obtain raw diff");
 411         fp = xfdopen(child->out, "r");
 412
 413         /* Build index info for left and right sides of the diff */
 414         i = 0;
 415         while (!strbuf_getline_nul(&info, fp)) {
 416                 int lmode, rmode;
 417                 struct object_id loid, roid;
 418                 char status;
 419                 const char *src_path, *dst_path;
 420
 421                 if (starts_with(info.buf, "::"))
 422                         die(N_("combined diff formats ('-c' and '--cc') are "
 423                                "not supported in\n"
 424                                "directory diff mode ('-d' and '--dir-diff')."));
 425
 426                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 427                                      &status))
 428                         break;
 429                 if (strbuf_getline_nul(&lpath, fp))
 430                         break;
 431                 src_path = lpath.buf;
 432
 433                 i++;
 434                 if (status != 'C' && status != 'R') {
 435                         dst_path = src_path;
 436                 } else {
 437                         if (strbuf_getline_nul(&rpath, fp))
 438                                 break;
 439                         dst_path = rpath.buf;
 440                 }
 441
 442                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 443                         strbuf_reset(&buf);
 444                         strbuf_addf(&buf, "Subproject commit %s",
 445                                     oid_to_hex(&loid));
 446                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 447                         strbuf_reset(&buf);
 448                         strbuf_addf(&buf, "Subproject commit %s",
 449                                     oid_to_hex(&roid));
 450                         if (oideq(&loid, &roid))
 451                                 strbuf_addstr(&buf, "-dirty");
 452                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 453                         continue;
 454                 }
 455
 456                 if (S_ISLNK(lmode)) {
 457                         char *content = get_symlink(&loid, src_path);
 458                         add_left_or_right(&symlinks2, src_path, content, 0);
 459                         free(content);
 460                 }
 461
 462                 if (S_ISLNK(rmode)) {
 463                         char *content = get_symlink(&roid, dst_path);
 464                         add_left_or_right(&symlinks2, dst_path, content, 1);
 465                         free(content);
 466                 }
 467
 468                 if (lmode && status != 'C') {
 469                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 470                                 ret = error("could not write '%s'", src_path);
 471                                 goto finish;
 472                         }
 473                 }
 474
 475                 if (rmode && !S_ISLNK(rmode)) {
 476                         struct working_tree_entry *entry;
 477
 478                         /* Avoid duplicate working_tree entries */
 479                         FLEX_ALLOC_STR(entry, path, dst_path);
 480                         hashmap_entry_init(&entry->entry, strhash(dst_path));
 481                         if (hashmap_get(&working_tree_dups, &entry->entry,
 482                                         NULL)) {
 483                                 free(entry);
 484                                 continue;
 485                         }
 486                         hashmap_add(&working_tree_dups, &entry->entry);
 487
 488                         if (!use_wt_file(workdir, dst_path, &roid)) {
 489                                 if (checkout_path(rmode, &roid, dst_path,
 490                                                   &rstate)) {
 491                                         ret = error("could not write '%s'",
 492                                                     dst_path);
 493                                         goto finish;
 494                                 }
 495                         } else if (!is_null_oid(&roid)) {
 496                                 /*
 497                                  * Changes in the working tree need special
 498                                  * treatment since they are not part of the
 499                                  * index.
 500                                  */
 501                                 struct cache_entry *ce2 =
 502                                         make_cache_entry(&wtindex, rmode, &roid,
 503                                                          dst_path, 0, 0);
 504
 505                                 add_index_entry(&wtindex, ce2,
 506                                                 ADD_CACHE_JUST_APPEND);
 507
 508                                 add_path(&rdir, rdir_len, dst_path);
 509                                 if (ensure_leading_directories(rdir.buf)) {
 510                                         ret = error("could not create "
 511                                                     "directory for '%s'",
 512                                                     dst_path);
 513                                         goto finish;
 514                                 }
 515                                 add_path(&wtdir, wtdir_len, dst_path);
 516                                 if (symlinks) {
 517                                         if (symlink(wtdir.buf, rdir.buf)) {
 518                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 519                                                 goto finish;
 520                                         }
 521                                 } else {
 522                                         struct stat st;
 523                                         if (stat(wtdir.buf, &st))
 524                                                 st.st_mode = 0644;
 525                                         if (copy_file(rdir.buf, wtdir.buf,
 526                                                       st.st_mode)) {
 527                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 528                                                 goto finish;
 529                                         }
 530                                 }
 531                         }
 532                 }
 533         }
 534
 535         fclose(fp);
 536         fp = NULL;
 537         if (finish_command(child)) {
 538                 ret = error("error occurred running diff --raw");
 539                 goto finish;
 540         }
 541
 542         if (!i)
 543                 goto finish;
 544
 545         /*
 546          * Changes to submodules require special treatment.This loop writes a
 547          * temporary file to both the left and right directories to show the
 548          * change in the recorded SHA1 for the submodule.
 549          */
 550         hashmap_for_each_entry(&submodules, &iter, entry,
 551                                 entry /* member name */) {
 552                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 553         }
 554
 555         /*
 556          * Symbolic links require special treatment. The standard "git diff"
 557          * shows only the link itself, not the contents of the link target.
 558          * This loop replicates that behavior.
 559          */
 560         hashmap_for_each_entry(&symlinks2, &iter, entry,
 561                                 entry /* member name */) {
 562
 563                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 564         }
 565
 566         strbuf_setlen(&ldir, ldir_len);
 567         strbuf_setlen(&rdir, rdir_len);
 568
 569         if (extcmd) {
 570                 strvec_push(&cmd.args, extcmd);
 571         } else {
 572                 strvec_push(&cmd.args, "difftool--helper");
 573                 cmd.git_cmd = 1;
 574                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 575         }
 576         strvec_pushl(&cmd.args, ldir.buf, rdir.buf, NULL);
 577         ret = run_command(&cmd);
 578
 579         /* TODO: audit for interaction with sparse-index. */
 580         ensure_full_index(&wtindex);
 581
 582         /*
 583          * If the diff includes working copy files and those
 584          * files were modified during the diff, then the changes
 585          * should be copied back to the working tree.
 586          * Do not copy back files when symlinks are used and the
 587          * external tool did not replace the original link with a file.
 588          *
 589          * These hashes are loaded lazily since they aren't needed
 590          * in the common case of --symlinks and the difftool updating
 591          * files through the symlink.
 592          */
 593         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 594         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 595
 596         for (i = 0; i < wtindex.cache_nr; i++) {
 597                 struct hashmap_entry dummy;
 598                 const char *name = wtindex.cache[i]->name;
 599                 struct stat st;
 600
 601                 add_path(&rdir, rdir_len, name);
 602                 if (lstat(rdir.buf, &st))
 603                         continue;
 604
 605                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 606                         continue;
 607
 608                 if (!indices_loaded) {
 609                         struct lock_file lock = LOCK_INIT;
 610                         strbuf_reset(&buf);
 611                         strbuf_addf(&buf, "%s/wtindex", tmpdir.buf);
 612                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 613                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 614                                 ret = error("could not write %s", buf.buf);
 615                                 goto finish;
 616                         }
 617                         changed_files(&wt_modified, buf.buf, workdir);
 618                         strbuf_setlen(&rdir, rdir_len);
 619                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 620                         add_path(&rdir, rdir_len, name);
 621                         indices_loaded = 1;
 622                 }
 623
 624                 hashmap_entry_init(&dummy, strhash(name));
 625                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 626                         add_path(&wtdir, wtdir_len, name);
 627                         if (hashmap_get(&wt_modified, &dummy, name)) {
 628                                 warning(_("both files modified: '%s' and '%s'."),
 629                                         wtdir.buf, rdir.buf);
 630                                 warning(_("working tree file has been left."));
 631                                 warning("%s", "");
 632                                 err = 1;
 633                         } else if (unlink(wtdir.buf) ||
 634                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 635                                 warning_errno(_("could not copy '%s' to '%s'"),
 636                                               rdir.buf, wtdir.buf);
 637                 }
 638         }
 639
 640         if (err) {
 641                 warning(_("temporary files exist in '%s'."), tmpdir.buf);
 642                 warning(_("you may want to cleanup or recover these."));
 643                 ret = 1;
 644         } else {
 645                 remove_dir_recursively(&tmpdir, 0);
 646                 if (ret)
 647                         warning(_("failed: %d"), ret);
 648         }
 649
 650 finish:
 651         if (fp)
 652                 fclose(fp);
 653
 654         free(lbase_dir);
 655         free(rbase_dir);
 656         strbuf_release(&ldir);
 657         strbuf_release(&rdir);
 658         strbuf_release(&wtdir);
 659         strbuf_release(&buf);
 660         strbuf_release(&tmpdir);
 661
 662         return (ret < 0) ? 1 : ret;
 663 }
 664
 665 static int run_file_diff(int prompt, const char *prefix,
 666                          struct child_process *child)
 667 {
 668         const char *env[] = {
 669                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 670                 NULL
 671         };
 672
 673         if (prompt > 0)
 674                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 675         else if (!prompt)
 676                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 677
 678         child->git_cmd = 1;
 679         child->dir = prefix;
 680         strvec_pushv(&child->env, env);
 681
 682         return run_command(child);
 683 }
 684
 685 int cmd_difftool(int argc, const char **argv, const char *prefix)
 686 {
 687         int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
 688             tool_help = 0, no_index = 0;
 689         static char *difftool_cmd = NULL, *extcmd = NULL;
 690         struct option builtin_difftool_options[] = {
 691                 OPT_BOOL('g', "gui", &use_gui_tool,
 692                          N_("use `diff.guitool` instead of `diff.tool`")),
 693                 OPT_BOOL('d', "dir-diff", &dir_diff,
 694                          N_("perform a full-directory diff")),
 695                 OPT_SET_INT_F('y', "no-prompt", &prompt,
 696                         N_("do not prompt before launching a diff tool"),
 697                         0, PARSE_OPT_NONEG),
 698                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
 699                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
 700                 OPT_BOOL(0, "symlinks", &symlinks,
 701                          N_("use symlinks in dir-diff mode")),
 702                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
 703                            N_("use the specified diff tool")),
 704                 OPT_BOOL(0, "tool-help", &tool_help,
 705                          N_("print a list of diff tools that may be used with "
 706                             "`--tool`")),
 707                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 708                          N_("make 'git-difftool' exit when an invoked diff "
 709                             "tool returns a non-zero exit code")),
 710                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 711                            N_("specify a custom command for viewing diffs")),
 712                 OPT_BOOL(0, "no-index", &no_index, N_("passed to `diff`")),
 713                 OPT_END()
 714         };
 715         struct child_process child = CHILD_PROCESS_INIT;
 716
 717         git_config(difftool_config, NULL);
 718         symlinks = has_symlinks;
 719
 720         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 721                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN_OPT |
 722                              PARSE_OPT_KEEP_DASHDASH);
 723
 724         if (tool_help)
 725                 return print_tool_help();
 726
 727         if (!no_index && !startup_info->have_repository)
 728                 die(_("difftool requires worktree or --no-index"));
 729
 730         if (!no_index){
 731                 setup_work_tree();
 732                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 733                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 734         } else if (dir_diff)
 735                 die(_("options '%s' and '%s' cannot be used together"), "--dir-diff", "--no-index");
 736
 737         die_for_incompatible_opt3(use_gui_tool, "--gui",
 738                                   !!difftool_cmd, "--tool",
 739                                   !!extcmd, "--extcmd");
 740
 741         if (use_gui_tool)
 742                 setenv("GIT_MERGETOOL_GUI", "true", 1);
 743         else if (difftool_cmd) {
 744                 if (*difftool_cmd)
 745                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 746                 else
 747                         die(_("no <tool> given for --tool=<tool>"));
 748         }
 749
 750         if (extcmd) {
 751                 if (*extcmd)
 752                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 753                 else
 754                         die(_("no <cmd> given for --extcmd=<cmd>"));
 755         }
 756
 757         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 758                trust_exit_code ? "true" : "false", 1);
 759
 760         /*
 761          * In directory diff mode, 'git-difftool--helper' is called once
 762          * to compare the a / b directories. In file diff mode, 'git diff'
 763          * will invoke a separate instance of 'git-difftool--helper' for
 764          * each file that changed.
 765          */
 766         strvec_push(&child.args, "diff");
 767         if (no_index)
 768                 strvec_push(&child.args, "--no-index");
 769         if (dir_diff)
 770                 strvec_pushl(&child.args, "--raw", "--no-abbrev", "-z", NULL);
 771         strvec_pushv(&child.args, argv);
 772
 773         if (dir_diff)
 774                 return run_dir_diff(extcmd, symlinks, prefix, &child);
 775         return run_file_diff(prompt, prefix, &child);
 776 }