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