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 "builtin.h"
  16 #include "abspath.h"
  17 #include "config.h"
  18 #include "copy.h"
  19 #include "run-command.h"
  20 #include "environment.h"
  21 #include "gettext.h"
  22 #include "hex.h"
  23 #include "parse-options.h"
  24 #include "read-cache-ll.h"
  25 #include "sparse-index.h"
  26 #include "strvec.h"
  27 #include "strbuf.h"
  28 #include "lockfile.h"
  29 #include "object-file.h"
  30 #include "object-store-ll.h"
  31 #include "dir.h"
  32 #include "entry.h"
  33 #include "setup.h"
  34
  35 static int trust_exit_code;
  36
  37 static const char *const builtin_difftool_usage[] = {
  38         N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
  39         NULL
  40 };
  41
  42 static int difftool_config(const char *var, const char *value,
  43                            const struct config_context *ctx, void *cb)
  44 {
  45         if (!strcmp(var, "difftool.trustexitcode")) {
  46                 trust_exit_code = git_config_bool(var, value);
  47                 return 0;
  48         }
  49
  50         return git_default_config(var, value, ctx, cb);
  51 }
  52
  53 static int print_tool_help(void)
  54 {
  55         struct child_process cmd = CHILD_PROCESS_INIT;
  56
  57         cmd.git_cmd = 1;
  58         strvec_pushl(&cmd.args, "mergetool", "--tool-help=diff", NULL);
  59         return run_command(&cmd);
  60 }
  61
  62 static int parse_index_info(char *p, int *mode1, int *mode2,
  63                             struct object_id *oid1, struct object_id *oid2,
  64                             char *status)
  65 {
  66         if (*p != ':')
  67                 return error("expected ':', got '%c'", *p);
  68         *mode1 = (int)strtol(p + 1, &p, 8);
  69         if (*p != ' ')
  70                 return error("expected ' ', got '%c'", *p);
  71         *mode2 = (int)strtol(p + 1, &p, 8);
  72         if (*p != ' ')
  73                 return error("expected ' ', got '%c'", *p);
  74         if (parse_oid_hex(++p, oid1, (const char **)&p))
  75                 return error("expected object ID, got '%s'", p);
  76         if (*p != ' ')
  77                 return error("expected ' ', got '%c'", *p);
  78         if (parse_oid_hex(++p, oid2, (const char **)&p))
  79                 return error("expected object ID, got '%s'", p);
  80         if (*p != ' ')
  81                 return error("expected ' ', got '%c'", *p);
  82         *status = *++p;
  83         if (!*status)
  84                 return error("missing status");
  85         if (p[1] && !isdigit(p[1]))
  86                 return error("unexpected trailer: '%s'", p + 1);
  87         return 0;
  88 }
  89
  90 /*
  91  * Remove any trailing slash from $workdir
  92  * before starting to avoid double slashes in symlink targets.
  93  */
  94 static void add_path(struct strbuf *buf, size_t base_len, const char *path)
  95 {
  96         strbuf_setlen(buf, base_len);
  97         if (buf->len && buf->buf[buf->len - 1] != '/')
  98                 strbuf_addch(buf, '/');
  99         strbuf_addstr(buf, path);
 100 }
 101
 102 /*
 103  * Determine whether we can simply reuse the file in the worktree.
 104  */
 105 static int use_wt_file(const char *workdir, const char *name,
 106                        struct object_id *oid)
 107 {
 108         struct strbuf buf = STRBUF_INIT;
 109         struct stat st;
 110         int use = 0;
 111
 112         strbuf_addstr(&buf, workdir);
 113         add_path(&buf, buf.len, name);
 114
 115         if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
 116                 struct object_id wt_oid;
 117                 int fd = open(buf.buf, O_RDONLY);
 118
 119                 if (fd >= 0 &&
 120                     !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
 121                         if (is_null_oid(oid)) {
 122                                 oidcpy(oid, &wt_oid);
 123                                 use = 1;
 124                         } else if (oideq(oid, &wt_oid))
 125                                 use = 1;
 126                 }
 127         }
 128
 129         strbuf_release(&buf);
 130
 131         return use;
 132 }
 133
 134 struct working_tree_entry {
 135         struct hashmap_entry entry;
 136         char path[FLEX_ARRAY];
 137 };
 138
 139 static int working_tree_entry_cmp(const void *cmp_data UNUSED,
 140                                   const struct hashmap_entry *eptr,
 141                                   const struct hashmap_entry *entry_or_key,
 142                                   const void *keydata UNUSED)
 143 {
 144         const struct working_tree_entry *a, *b;
 145
 146         a = container_of(eptr, const struct working_tree_entry, entry);
 147         b = container_of(entry_or_key, const struct working_tree_entry, entry);
 148
 149         return strcmp(a->path, b->path);
 150 }
 151
 152 /*
 153  * The `left` and `right` entries hold paths for the symlinks hashmap,
 154  * and a SHA-1 surrounded by brief text for submodules.
 155  */
 156 struct pair_entry {
 157         struct hashmap_entry entry;
 158         char left[PATH_MAX], right[PATH_MAX];
 159         const char path[FLEX_ARRAY];
 160 };
 161
 162 static int pair_cmp(const void *cmp_data UNUSED,
 163                     const struct hashmap_entry *eptr,
 164                     const struct hashmap_entry *entry_or_key,
 165                     const void *keydata UNUSED)
 166 {
 167         const struct pair_entry *a, *b;
 168
 169         a = container_of(eptr, const struct pair_entry, entry);
 170         b = container_of(entry_or_key, const struct pair_entry, entry);
 171
 172         return strcmp(a->path, b->path);
 173 }
 174
 175 static void add_left_or_right(struct hashmap *map, const char *path,
 176                               const char *content, int is_right)
 177 {
 178         struct pair_entry *e, *existing;
 179
 180         FLEX_ALLOC_STR(e, path, path);
 181         hashmap_entry_init(&e->entry, strhash(path));
 182         existing = hashmap_get_entry(map, e, entry, NULL);
 183         if (existing) {
 184                 free(e);
 185                 e = existing;
 186         } else {
 187                 e->left[0] = e->right[0] = '\0';
 188                 hashmap_add(map, &e->entry);
 189         }
 190         strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
 191 }
 192
 193 struct path_entry {
 194         struct hashmap_entry entry;
 195         char path[FLEX_ARRAY];
 196 };
 197
 198 static int path_entry_cmp(const void *cmp_data UNUSED,
 199                           const struct hashmap_entry *eptr,
 200                           const struct hashmap_entry *entry_or_key,
 201                           const void *key)
 202 {
 203         const struct path_entry *a, *b;
 204
 205         a = container_of(eptr, const struct path_entry, entry);
 206         b = container_of(entry_or_key, const struct path_entry, entry);
 207
 208         return strcmp(a->path, key ? key : b->path);
 209 }
 210
 211 static void changed_files(struct hashmap *result, const char *index_path,
 212                           const char *workdir)
 213 {
 214         struct child_process update_index = CHILD_PROCESS_INIT;
 215         struct child_process diff_files = CHILD_PROCESS_INIT;
 216         struct strbuf buf = STRBUF_INIT;
 217         const char *git_dir = absolute_path(get_git_dir());
 218         FILE *fp;
 219
 220         strvec_pushl(&update_index.args,
 221                      "--git-dir", git_dir, "--work-tree", workdir,
 222                      "update-index", "--really-refresh", "-q",
 223                      "--unmerged", NULL);
 224         update_index.no_stdin = 1;
 225         update_index.no_stdout = 1;
 226         update_index.no_stderr = 1;
 227         update_index.git_cmd = 1;
 228         update_index.use_shell = 0;
 229         update_index.clean_on_exit = 1;
 230         update_index.dir = workdir;
 231         strvec_pushf(&update_index.env, "GIT_INDEX_FILE=%s", index_path);
 232         /* Ignore any errors of update-index */
 233         run_command(&update_index);
 234
 235         strvec_pushl(&diff_files.args,
 236                      "--git-dir", git_dir, "--work-tree", workdir,
 237                      "diff-files", "--name-only", "-z", NULL);
 238         diff_files.no_stdin = 1;
 239         diff_files.git_cmd = 1;
 240         diff_files.use_shell = 0;
 241         diff_files.clean_on_exit = 1;
 242         diff_files.out = -1;
 243         diff_files.dir = workdir;
 244         strvec_pushf(&diff_files.env, "GIT_INDEX_FILE=%s", index_path);
 245         if (start_command(&diff_files))
 246                 die("could not obtain raw diff");
 247         fp = xfdopen(diff_files.out, "r");
 248         while (!strbuf_getline_nul(&buf, fp)) {
 249                 struct path_entry *entry;
 250                 FLEX_ALLOC_STR(entry, path, buf.buf);
 251                 hashmap_entry_init(&entry->entry, strhash(buf.buf));
 252                 hashmap_add(result, &entry->entry);
 253         }
 254         fclose(fp);
 255         if (finish_command(&diff_files))
 256                 die("diff-files did not exit properly");
 257         strbuf_release(&buf);
 258 }
 259
 260 static int ensure_leading_directories(char *path)
 261 {
 262         switch (safe_create_leading_directories(path)) {
 263                 case SCLD_OK:
 264                 case SCLD_EXISTS:
 265                         return 0;
 266                 default:
 267                         return error(_("could not create leading directories "
 268                                        "of '%s'"), path);
 269         }
 270 }
 271
 272 /*
 273  * Unconditional writing of a plain regular file is what
 274  * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
 275  * temporary directories to be fed to a Git-unaware tool that knows how to
 276  * show a diff of two directories (e.g. "diff -r A B").
 277  *
 278  * Because the tool is Git-unaware, if a symbolic link appears in either of
 279  * these temporary directories, it will try to dereference and show the
 280  * difference of the target of the symbolic link, which is not what we want,
 281  * as the goal of the dir-diff mode is to produce an output that is logically
 282  * equivalent to what "git diff" produces.
 283  *
 284  * Most importantly, we want to get textual comparison of the result of the
 285  * readlink(2).  get_symlink() provides that---it returns the contents of
 286  * the symlink that gets written to a regular file to force the external tool
 287  * to compare the readlink(2) result as text, even on a filesystem that is
 288  * capable of doing a symbolic link.
 289  */
 290 static char *get_symlink(const struct object_id *oid, const char *path)
 291 {
 292         char *data;
 293         if (is_null_oid(oid)) {
 294                 /* The symlink is unknown to Git so read from the filesystem */
 295                 struct strbuf link = STRBUF_INIT;
 296                 if (has_symlinks) {
 297                         if (strbuf_readlink(&link, path, strlen(path)))
 298                                 die(_("could not read symlink %s"), path);
 299                 } else if (strbuf_read_file(&link, path, 128))
 300                         die(_("could not read symlink file %s"), path);
 301
 302                 data = strbuf_detach(&link, NULL);
 303         } else {
 304                 enum object_type type;
 305                 unsigned long size;
 306                 data = repo_read_object_file(the_repository, oid, &type,
 307                                              &size);
 308                 if (!data)
 309                         die(_("could not read object %s for symlink %s"),
 310                                 oid_to_hex(oid), path);
 311         }
 312
 313         return data;
 314 }
 315
 316 static int checkout_path(unsigned mode, struct object_id *oid,
 317                          const char *path, const struct checkout *state)
 318 {
 319         struct cache_entry *ce;
 320         int ret;
 321
 322         ce = make_transient_cache_entry(mode, oid, path, 0, NULL);
 323         ret = checkout_entry(ce, state, NULL, NULL);
 324
 325         discard_cache_entry(ce);
 326         return ret;
 327 }
 328
 329 static void write_file_in_directory(struct strbuf *dir, size_t dir_len,
 330                         const char *path, const char *content)
 331 {
 332         add_path(dir, dir_len, path);
 333         ensure_leading_directories(dir->buf);
 334         unlink(dir->buf);
 335         write_file(dir->buf, "%s", content);
 336 }
 337
 338 /* Write the file contents for the left and right sides of the difftool
 339  * dir-diff representation for submodules and symlinks. Symlinks and submodules
 340  * are written as regular text files so that external diff tools can diff them
 341  * as text files, resulting in behavior that is analogous to to what "git diff"
 342  * displays for symlink and submodule diffs.
 343  */
 344 static void write_standin_files(struct pair_entry *entry,
 345                         struct strbuf *ldir, size_t ldir_len,
 346                         struct strbuf *rdir, size_t rdir_len)
 347 {
 348         if (*entry->left)
 349                 write_file_in_directory(ldir, ldir_len, entry->path, entry->left);
 350         if (*entry->right)
 351                 write_file_in_directory(rdir, rdir_len, entry->path, entry->right);
 352 }
 353
 354 static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 355                         struct child_process *child)
 356 {
 357         struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
 358         struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
 359         struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
 360         struct strbuf wtdir = STRBUF_INIT;
 361         struct strbuf tmpdir = STRBUF_INIT;
 362         char *lbase_dir = NULL, *rbase_dir = NULL;
 363         size_t ldir_len, rdir_len, wtdir_len;
 364         const char *workdir, *tmp;
 365         int ret = 0, i;
 366         FILE *fp = NULL;
 367         struct hashmap working_tree_dups = HASHMAP_INIT(working_tree_entry_cmp,
 368                                                         NULL);
 369         struct hashmap submodules = HASHMAP_INIT(pair_cmp, NULL);
 370         struct hashmap symlinks2 = HASHMAP_INIT(pair_cmp, NULL);
 371         struct hashmap_iter iter;
 372         struct pair_entry *entry;
 373         struct index_state wtindex = INDEX_STATE_INIT(the_repository);
 374         struct checkout lstate, rstate;
 375         int err = 0;
 376         struct child_process cmd = CHILD_PROCESS_INIT;
 377         struct hashmap wt_modified, tmp_modified;
 378         int indices_loaded = 0;
 379
 380         workdir = get_git_work_tree();
 381
 382         /* Setup temp directories */
 383         tmp = getenv("TMPDIR");
 384         strbuf_add_absolute_path(&tmpdir, tmp ? tmp : "/tmp");
 385         strbuf_trim_trailing_dir_sep(&tmpdir);
 386         strbuf_addstr(&tmpdir, "/git-difftool.XXXXXX");
 387         if (!mkdtemp(tmpdir.buf)) {
 388                 ret = error("could not create '%s'", tmpdir.buf);
 389                 goto finish;
 390         }
 391         strbuf_addf(&ldir, "%s/left/", tmpdir.buf);
 392         strbuf_addf(&rdir, "%s/right/", tmpdir.buf);
 393         strbuf_addstr(&wtdir, workdir);
 394         if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
 395                 strbuf_addch(&wtdir, '/');
 396         mkdir(ldir.buf, 0700);
 397         mkdir(rdir.buf, 0700);
 398
 399         memset(&lstate, 0, sizeof(lstate));
 400         lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
 401         lstate.base_dir_len = ldir.len;
 402         lstate.force = 1;
 403         memset(&rstate, 0, sizeof(rstate));
 404         rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
 405         rstate.base_dir_len = rdir.len;
 406         rstate.force = 1;
 407
 408         ldir_len = ldir.len;
 409         rdir_len = rdir.len;
 410         wtdir_len = wtdir.len;
 411
 412         child->no_stdin = 1;
 413         child->git_cmd = 1;
 414         child->use_shell = 0;
 415         child->clean_on_exit = 1;
 416         child->dir = prefix;
 417         child->out = -1;
 418         if (start_command(child))
 419                 die("could not obtain raw diff");
 420         fp = xfdopen(child->out, "r");
 421
 422         /* Build index info for left and right sides of the diff */
 423         i = 0;
 424         while (!strbuf_getline_nul(&info, fp)) {
 425                 int lmode, rmode;
 426                 struct object_id loid, roid;
 427                 char status;
 428                 const char *src_path, *dst_path;
 429
 430                 if (starts_with(info.buf, "::"))
 431                         die(N_("combined diff formats ('-c' and '--cc') are "
 432                                "not supported in\n"
 433                                "directory diff mode ('-d' and '--dir-diff')."));
 434
 435                 if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
 436                                      &status))
 437                         break;
 438                 if (strbuf_getline_nul(&lpath, fp))
 439                         break;
 440                 src_path = lpath.buf;
 441
 442                 i++;
 443                 if (status != 'C' && status != 'R') {
 444                         dst_path = src_path;
 445                 } else {
 446                         if (strbuf_getline_nul(&rpath, fp))
 447                                 break;
 448                         dst_path = rpath.buf;
 449                 }
 450
 451                 if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
 452                         strbuf_reset(&buf);
 453                         strbuf_addf(&buf, "Subproject commit %s",
 454                                     oid_to_hex(&loid));
 455                         add_left_or_right(&submodules, src_path, buf.buf, 0);
 456                         strbuf_reset(&buf);
 457                         strbuf_addf(&buf, "Subproject commit %s",
 458                                     oid_to_hex(&roid));
 459                         if (oideq(&loid, &roid))
 460                                 strbuf_addstr(&buf, "-dirty");
 461                         add_left_or_right(&submodules, dst_path, buf.buf, 1);
 462                         continue;
 463                 }
 464
 465                 if (S_ISLNK(lmode)) {
 466                         char *content = get_symlink(&loid, src_path);
 467                         add_left_or_right(&symlinks2, src_path, content, 0);
 468                         free(content);
 469                 }
 470
 471                 if (S_ISLNK(rmode)) {
 472                         char *content = get_symlink(&roid, dst_path);
 473                         add_left_or_right(&symlinks2, dst_path, content, 1);
 474                         free(content);
 475                 }
 476
 477                 if (lmode && status != 'C') {
 478                         if (checkout_path(lmode, &loid, src_path, &lstate)) {
 479                                 ret = error("could not write '%s'", src_path);
 480                                 goto finish;
 481                         }
 482                 }
 483
 484                 if (rmode && !S_ISLNK(rmode)) {
 485                         struct working_tree_entry *entry;
 486
 487                         /* Avoid duplicate working_tree entries */
 488                         FLEX_ALLOC_STR(entry, path, dst_path);
 489                         hashmap_entry_init(&entry->entry, strhash(dst_path));
 490                         if (hashmap_get(&working_tree_dups, &entry->entry,
 491                                         NULL)) {
 492                                 free(entry);
 493                                 continue;
 494                         }
 495                         hashmap_add(&working_tree_dups, &entry->entry);
 496
 497                         if (!use_wt_file(workdir, dst_path, &roid)) {
 498                                 if (checkout_path(rmode, &roid, dst_path,
 499                                                   &rstate)) {
 500                                         ret = error("could not write '%s'",
 501                                                     dst_path);
 502                                         goto finish;
 503                                 }
 504                         } else if (!is_null_oid(&roid)) {
 505                                 /*
 506                                  * Changes in the working tree need special
 507                                  * treatment since they are not part of the
 508                                  * index.
 509                                  */
 510                                 struct cache_entry *ce2 =
 511                                         make_cache_entry(&wtindex, rmode, &roid,
 512                                                          dst_path, 0, 0);
 513
 514                                 add_index_entry(&wtindex, ce2,
 515                                                 ADD_CACHE_JUST_APPEND);
 516
 517                                 add_path(&rdir, rdir_len, dst_path);
 518                                 if (ensure_leading_directories(rdir.buf)) {
 519                                         ret = error("could not create "
 520                                                     "directory for '%s'",
 521                                                     dst_path);
 522                                         goto finish;
 523                                 }
 524                                 add_path(&wtdir, wtdir_len, dst_path);
 525                                 if (symlinks) {
 526                                         if (symlink(wtdir.buf, rdir.buf)) {
 527                                                 ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
 528                                                 goto finish;
 529                                         }
 530                                 } else {
 531                                         struct stat st;
 532                                         if (stat(wtdir.buf, &st))
 533                                                 st.st_mode = 0644;
 534                                         if (copy_file(rdir.buf, wtdir.buf,
 535                                                       st.st_mode)) {
 536                                                 ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
 537                                                 goto finish;
 538                                         }
 539                                 }
 540                         }
 541                 }
 542         }
 543
 544         fclose(fp);
 545         fp = NULL;
 546         if (finish_command(child)) {
 547                 ret = error("error occurred running diff --raw");
 548                 goto finish;
 549         }
 550
 551         if (!i)
 552                 goto finish;
 553
 554         /*
 555          * Changes to submodules require special treatment.This loop writes a
 556          * temporary file to both the left and right directories to show the
 557          * change in the recorded SHA1 for the submodule.
 558          */
 559         hashmap_for_each_entry(&submodules, &iter, entry,
 560                                 entry /* member name */) {
 561                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 562         }
 563
 564         /*
 565          * Symbolic links require special treatment. The standard "git diff"
 566          * shows only the link itself, not the contents of the link target.
 567          * This loop replicates that behavior.
 568          */
 569         hashmap_for_each_entry(&symlinks2, &iter, entry,
 570                                 entry /* member name */) {
 571
 572                 write_standin_files(entry, &ldir, ldir_len, &rdir, rdir_len);
 573         }
 574
 575         strbuf_setlen(&ldir, ldir_len);
 576         strbuf_setlen(&rdir, rdir_len);
 577
 578         if (extcmd) {
 579                 strvec_push(&cmd.args, extcmd);
 580         } else {
 581                 strvec_push(&cmd.args, "difftool--helper");
 582                 cmd.git_cmd = 1;
 583                 setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
 584         }
 585         strvec_pushl(&cmd.args, ldir.buf, rdir.buf, NULL);
 586         ret = run_command(&cmd);
 587
 588         /* TODO: audit for interaction with sparse-index. */
 589         ensure_full_index(&wtindex);
 590
 591         /*
 592          * If the diff includes working copy files and those
 593          * files were modified during the diff, then the changes
 594          * should be copied back to the working tree.
 595          * Do not copy back files when symlinks are used and the
 596          * external tool did not replace the original link with a file.
 597          *
 598          * These hashes are loaded lazily since they aren't needed
 599          * in the common case of --symlinks and the difftool updating
 600          * files through the symlink.
 601          */
 602         hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 603         hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 604
 605         for (i = 0; i < wtindex.cache_nr; i++) {
 606                 struct hashmap_entry dummy;
 607                 const char *name = wtindex.cache[i]->name;
 608                 struct stat st;
 609
 610                 add_path(&rdir, rdir_len, name);
 611                 if (lstat(rdir.buf, &st))
 612                         continue;
 613
 614                 if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
 615                         continue;
 616
 617                 if (!indices_loaded) {
 618                         struct lock_file lock = LOCK_INIT;
 619                         strbuf_reset(&buf);
 620                         strbuf_addf(&buf, "%s/wtindex", tmpdir.buf);
 621                         if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
 622                             write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
 623                                 ret = error("could not write %s", buf.buf);
 624                                 goto finish;
 625                         }
 626                         changed_files(&wt_modified, buf.buf, workdir);
 627                         strbuf_setlen(&rdir, rdir_len);
 628                         changed_files(&tmp_modified, buf.buf, rdir.buf);
 629                         add_path(&rdir, rdir_len, name);
 630                         indices_loaded = 1;
 631                 }
 632
 633                 hashmap_entry_init(&dummy, strhash(name));
 634                 if (hashmap_get(&tmp_modified, &dummy, name)) {
 635                         add_path(&wtdir, wtdir_len, name);
 636                         if (hashmap_get(&wt_modified, &dummy, name)) {
 637                                 warning(_("both files modified: '%s' and '%s'."),
 638                                         wtdir.buf, rdir.buf);
 639                                 warning(_("working tree file has been left."));
 640                                 warning("%s", "");
 641                                 err = 1;
 642                         } else if (unlink(wtdir.buf) ||
 643                                    copy_file(wtdir.buf, rdir.buf, st.st_mode))
 644                                 warning_errno(_("could not copy '%s' to '%s'"),
 645                                               rdir.buf, wtdir.buf);
 646                 }
 647         }
 648
 649         if (err) {
 650                 warning(_("temporary files exist in '%s'."), tmpdir.buf);
 651                 warning(_("you may want to cleanup or recover these."));
 652                 ret = 1;
 653         } else {
 654                 remove_dir_recursively(&tmpdir, 0);
 655                 if (ret)
 656                         warning(_("failed: %d"), ret);
 657         }
 658
 659 finish:
 660         if (fp)
 661                 fclose(fp);
 662
 663         free(lbase_dir);
 664         free(rbase_dir);
 665         strbuf_release(&ldir);
 666         strbuf_release(&rdir);
 667         strbuf_release(&wtdir);
 668         strbuf_release(&buf);
 669         strbuf_release(&tmpdir);
 670
 671         return (ret < 0) ? 1 : ret;
 672 }
 673
 674 static int run_file_diff(int prompt, const char *prefix,
 675                          struct child_process *child)
 676 {
 677         const char *env[] = {
 678                 "GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
 679                 NULL
 680         };
 681
 682         if (prompt > 0)
 683                 env[2] = "GIT_DIFFTOOL_PROMPT=true";
 684         else if (!prompt)
 685                 env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
 686
 687         child->git_cmd = 1;
 688         child->dir = prefix;
 689         strvec_pushv(&child->env, env);
 690
 691         return run_command(child);
 692 }
 693
 694 int cmd_difftool(int argc, const char **argv, const char *prefix)
 695 {
 696         int use_gui_tool = -1, dir_diff = 0, prompt = -1, symlinks = 0,
 697             tool_help = 0, no_index = 0;
 698         static char *difftool_cmd = NULL, *extcmd = NULL;
 699         struct option builtin_difftool_options[] = {
 700                 OPT_BOOL('g', "gui", &use_gui_tool,
 701                          N_("use `diff.guitool` instead of `diff.tool`")),
 702                 OPT_BOOL('d', "dir-diff", &dir_diff,
 703                          N_("perform a full-directory diff")),
 704                 OPT_SET_INT_F('y', "no-prompt", &prompt,
 705                         N_("do not prompt before launching a diff tool"),
 706                         0, PARSE_OPT_NONEG),
 707                 OPT_SET_INT_F(0, "prompt", &prompt, NULL,
 708                         1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
 709                 OPT_BOOL(0, "symlinks", &symlinks,
 710                          N_("use symlinks in dir-diff mode")),
 711                 OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
 712                            N_("use the specified diff tool")),
 713                 OPT_BOOL(0, "tool-help", &tool_help,
 714                          N_("print a list of diff tools that may be used with "
 715                             "`--tool`")),
 716                 OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
 717                          N_("make 'git-difftool' exit when an invoked diff "
 718                             "tool returns a non-zero exit code")),
 719                 OPT_STRING('x', "extcmd", &extcmd, N_("command"),
 720                            N_("specify a custom command for viewing diffs")),
 721                 OPT_BOOL(0, "no-index", &no_index, N_("passed to `diff`")),
 722                 OPT_END()
 723         };
 724         struct child_process child = CHILD_PROCESS_INIT;
 725
 726         git_config(difftool_config, NULL);
 727         symlinks = has_symlinks;
 728
 729         argc = parse_options(argc, argv, prefix, builtin_difftool_options,
 730                              builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN_OPT |
 731                              PARSE_OPT_KEEP_DASHDASH);
 732
 733         if (tool_help)
 734                 return print_tool_help();
 735
 736         if (!no_index && !startup_info->have_repository)
 737                 die(_("difftool requires worktree or --no-index"));
 738
 739         if (!no_index){
 740                 setup_work_tree();
 741                 setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
 742                 setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
 743         } else if (dir_diff)
 744                 die(_("options '%s' and '%s' cannot be used together"), "--dir-diff", "--no-index");
 745
 746         die_for_incompatible_opt3(use_gui_tool == 1, "--gui",
 747                                   !!difftool_cmd, "--tool",
 748                                   !!extcmd, "--extcmd");
 749
 750         /*
 751          * Explicitly specified GUI option is forwarded to git-mergetool--lib.sh;
 752          * empty or unset means "use the difftool.guiDefault config or default to
 753          * false".
 754          */
 755         if (use_gui_tool == 1)
 756                 setenv("GIT_MERGETOOL_GUI", "true", 1);
 757         else if (use_gui_tool == 0)
 758                 setenv("GIT_MERGETOOL_GUI", "false", 1);
 759
 760         if (difftool_cmd) {
 761                 if (*difftool_cmd)
 762                         setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
 763                 else
 764                         die(_("no <tool> given for --tool=<tool>"));
 765         }
 766
 767         if (extcmd) {
 768                 if (*extcmd)
 769                         setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
 770                 else
 771                         die(_("no <cmd> given for --extcmd=<cmd>"));
 772         }
 773
 774         setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
 775                trust_exit_code ? "true" : "false", 1);
 776
 777         /*
 778          * In directory diff mode, 'git-difftool--helper' is called once
 779          * to compare the a / b directories. In file diff mode, 'git diff'
 780          * will invoke a separate instance of 'git-difftool--helper' for
 781          * each file that changed.
 782          */
 783         strvec_push(&child.args, "diff");
 784         if (no_index)
 785                 strvec_push(&child.args, "--no-index");
 786         if (dir_diff)
 787                 strvec_pushl(&child.args, "--raw", "--no-abbrev", "-z", NULL);
 788         strvec_pushv(&child.args, argv);
 789
 790         if (dir_diff)
 791                 return run_dir_diff(extcmd, symlinks, prefix, &child);
 792         return run_file_diff(prompt, prefix, &child);
 793 }