path.c

   1 /*
   2  * Utilities for paths and pathnames
   3  */
   4 #include "cache.h"
   5 #include "repository.h"
   6 #include "strbuf.h"
   7 #include "string-list.h"
   8 #include "dir.h"
   9 #include "worktree.h"
  10 #include "submodule-config.h"
  11 #include "path.h"
  12
  13 static int get_st_mode_bits(const char *path, int *mode)
  14 {
  15         struct stat st;
  16         if (lstat(path, &st) < 0)
  17                 return -1;
  18         *mode = st.st_mode;
  19         return 0;
  20 }
  21
  22 static char bad_path[] = "/bad-path/";
  23
  24 static struct strbuf *get_pathname(void)
  25 {
  26         static struct strbuf pathname_array[4] = {
  27                 STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
  28         };
  29         static int index;
  30         struct strbuf *sb = &pathname_array[index];
  31         index = (index + 1) % ARRAY_SIZE(pathname_array);
  32         strbuf_reset(sb);
  33         return sb;
  34 }
  35
  36 static const char *cleanup_path(const char *path)
  37 {
  38         /* Clean it up */
  39         if (skip_prefix(path, "./", &path)) {
  40                 while (*path == '/')
  41                         path++;
  42         }
  43         return path;
  44 }
  45
  46 static void strbuf_cleanup_path(struct strbuf *sb)
  47 {
  48         const char *path = cleanup_path(sb->buf);
  49         if (path > sb->buf)
  50                 strbuf_remove(sb, 0, path - sb->buf);
  51 }
  52
  53 char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  54 {
  55         va_list args;
  56         unsigned len;
  57
  58         va_start(args, fmt);
  59         len = vsnprintf(buf, n, fmt, args);
  60         va_end(args);
  61         if (len >= n) {
  62                 strlcpy(buf, bad_path, n);
  63                 return buf;
  64         }
  65         return (char *)cleanup_path(buf);
  66 }
  67
  68 static int dir_prefix(const char *buf, const char *dir)
  69 {
  70         int len = strlen(dir);
  71         return !strncmp(buf, dir, len) &&
  72                 (is_dir_sep(buf[len]) || buf[len] == '\0');
  73 }
  74
  75 /* $buf =~ m|$dir/+$file| but without regex */
  76 static int is_dir_file(const char *buf, const char *dir, const char *file)
  77 {
  78         int len = strlen(dir);
  79         if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
  80                 return 0;
  81         while (is_dir_sep(buf[len]))
  82                 len++;
  83         return !strcmp(buf + len, file);
  84 }
  85
  86 static void replace_dir(struct strbuf *buf, int len, const char *newdir)
  87 {
  88         int newlen = strlen(newdir);
  89         int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
  90                 !is_dir_sep(newdir[newlen - 1]);
  91         if (need_sep)
  92                 len--;   /* keep one char, to be replaced with '/'  */
  93         strbuf_splice(buf, 0, len, newdir, newlen);
  94         if (need_sep)
  95                 buf->buf[newlen] = '/';
  96 }
  97
  98 struct common_dir {
  99         /* Not considered garbage for report_linked_checkout_garbage */
 100         unsigned ignore_garbage:1;
 101         unsigned is_dir:1;
 102         /* Not common even though its parent is */
 103         unsigned exclude:1;
 104         const char *dirname;
 105 };
 106
 107 static struct common_dir common_list[] = {
 108         { 0, 1, 0, "branches" },
 109         { 0, 1, 0, "hooks" },
 110         { 0, 1, 0, "info" },
 111         { 0, 0, 1, "info/sparse-checkout" },
 112         { 1, 1, 0, "logs" },
 113         { 1, 1, 1, "logs/HEAD" },
 114         { 0, 1, 1, "logs/refs/bisect" },
 115         { 0, 1, 0, "lost-found" },
 116         { 0, 1, 0, "objects" },
 117         { 0, 1, 0, "refs" },
 118         { 0, 1, 1, "refs/bisect" },
 119         { 0, 1, 0, "remotes" },
 120         { 0, 1, 0, "worktrees" },
 121         { 0, 1, 0, "rr-cache" },
 122         { 0, 1, 0, "svn" },
 123         { 0, 0, 0, "config" },
 124         { 1, 0, 0, "gc.pid" },
 125         { 0, 0, 0, "packed-refs" },
 126         { 0, 0, 0, "shallow" },
 127         { 0, 0, 0, NULL }
 128 };
 129
 130 /*
 131  * A compressed trie.  A trie node consists of zero or more characters that
 132  * are common to all elements with this prefix, optionally followed by some
 133  * children.  If value is not NULL, the trie node is a terminal node.
 134  *
 135  * For example, consider the following set of strings:
 136  * abc
 137  * def
 138  * definite
 139  * definition
 140  *
 141  * The trie would look like:
 142  * root: len = 0, children a and d non-NULL, value = NULL.
 143  *    a: len = 2, contents = bc, value = (data for "abc")
 144  *    d: len = 2, contents = ef, children i non-NULL, value = (data for "def")
 145  *       i: len = 3, contents = nit, children e and i non-NULL, value = NULL
 146  *           e: len = 0, children all NULL, value = (data for "definite")
 147  *           i: len = 2, contents = on, children all NULL,
 148  *              value = (data for "definition")
 149  */
 150 struct trie {
 151         struct trie *children[256];
 152         int len;
 153         char *contents;
 154         void *value;
 155 };
 156
 157 static struct trie *make_trie_node(const char *key, void *value)
 158 {
 159         struct trie *new_node = xcalloc(1, sizeof(*new_node));
 160         new_node->len = strlen(key);
 161         if (new_node->len) {
 162                 new_node->contents = xmalloc(new_node->len);
 163                 memcpy(new_node->contents, key, new_node->len);
 164         }
 165         new_node->value = value;
 166         return new_node;
 167 }
 168
 169 /*
 170  * Add a key/value pair to a trie.  The key is assumed to be \0-terminated.
 171  * If there was an existing value for this key, return it.
 172  */
 173 static void *add_to_trie(struct trie *root, const char *key, void *value)
 174 {
 175         struct trie *child;
 176         void *old;
 177         int i;
 178
 179         if (!*key) {
 180                 /* we have reached the end of the key */
 181                 old = root->value;
 182                 root->value = value;
 183                 return old;
 184         }
 185
 186         for (i = 0; i < root->len; i++) {
 187                 if (root->contents[i] == key[i])
 188                         continue;
 189
 190                 /*
 191                  * Split this node: child will contain this node's
 192                  * existing children.
 193                  */
 194                 child = malloc(sizeof(*child));
 195                 memcpy(child->children, root->children, sizeof(root->children));
 196
 197                 child->len = root->len - i - 1;
 198                 if (child->len) {
 199                         child->contents = xstrndup(root->contents + i + 1,
 200                                                    child->len);
 201                 }
 202                 child->value = root->value;
 203                 root->value = NULL;
 204                 root->len = i;
 205
 206                 memset(root->children, 0, sizeof(root->children));
 207                 root->children[(unsigned char)root->contents[i]] = child;
 208
 209                 /* This is the newly-added child. */
 210                 root->children[(unsigned char)key[i]] =
 211                         make_trie_node(key + i + 1, value);
 212                 return NULL;
 213         }
 214
 215         /* We have matched the entire compressed section */
 216         if (key[i]) {
 217                 child = root->children[(unsigned char)key[root->len]];
 218                 if (child) {
 219                         return add_to_trie(child, key + root->len + 1, value);
 220                 } else {
 221                         child = make_trie_node(key + root->len + 1, value);
 222                         root->children[(unsigned char)key[root->len]] = child;
 223                         return NULL;
 224                 }
 225         }
 226
 227         old = root->value;
 228         root->value = value;
 229         return old;
 230 }
 231
 232 typedef int (*match_fn)(const char *unmatched, void *data, void *baton);
 233
 234 /*
 235  * Search a trie for some key.  Find the longest /-or-\0-terminated
 236  * prefix of the key for which the trie contains a value.  Call fn
 237  * with the unmatched portion of the key and the found value, and
 238  * return its return value.  If there is no such prefix, return -1.
 239  *
 240  * The key is partially normalized: consecutive slashes are skipped.
 241  *
 242  * For example, consider the trie containing only [refs,
 243  * refs/worktree] (both with values).
 244  *
 245  * | key             | unmatched  | val from node | return value |
 246  * |-----------------|------------|---------------|--------------|
 247  * | a               | not called | n/a           | -1           |
 248  * | refs            | \0         | refs          | as per fn    |
 249  * | refs/           | /          | refs          | as per fn    |
 250  * | refs/w          | /w         | refs          | as per fn    |
 251  * | refs/worktree   | \0         | refs/worktree | as per fn    |
 252  * | refs/worktree/  | /          | refs/worktree | as per fn    |
 253  * | refs/worktree/a | /a         | refs/worktree | as per fn    |
 254  * |-----------------|------------|---------------|--------------|
 255  *
 256  */
 257 static int trie_find(struct trie *root, const char *key, match_fn fn,
 258                      void *baton)
 259 {
 260         int i;
 261         int result;
 262         struct trie *child;
 263
 264         if (!*key) {
 265                 /* we have reached the end of the key */
 266                 if (root->value && !root->len)
 267                         return fn(key, root->value, baton);
 268                 else
 269                         return -1;
 270         }
 271
 272         for (i = 0; i < root->len; i++) {
 273                 /* Partial path normalization: skip consecutive slashes. */
 274                 if (key[i] == '/' && key[i+1] == '/') {
 275                         key++;
 276                         continue;
 277                 }
 278                 if (root->contents[i] != key[i])
 279                         return -1;
 280         }
 281
 282         /* Matched the entire compressed section */
 283         key += i;
 284         if (!*key)
 285                 /* End of key */
 286                 return fn(key, root->value, baton);
 287
 288         /* Partial path normalization: skip consecutive slashes */
 289         while (key[0] == '/' && key[1] == '/')
 290                 key++;
 291
 292         child = root->children[(unsigned char)*key];
 293         if (child)
 294                 result = trie_find(child, key + 1, fn, baton);
 295         else
 296                 result = -1;
 297
 298         if (result >= 0 || (*key != '/' && *key != 0))
 299                 return result;
 300         if (root->value)
 301                 return fn(key, root->value, baton);
 302         else
 303                 return -1;
 304 }
 305
 306 static struct trie common_trie;
 307 static int common_trie_done_setup;
 308
 309 static void init_common_trie(void)
 310 {
 311         struct common_dir *p;
 312
 313         if (common_trie_done_setup)
 314                 return;
 315
 316         for (p = common_list; p->dirname; p++)
 317                 add_to_trie(&common_trie, p->dirname, p);
 318
 319         common_trie_done_setup = 1;
 320 }
 321
 322 /*
 323  * Helper function for update_common_dir: returns 1 if the dir
 324  * prefix is common.
 325  */
 326 static int check_common(const char *unmatched, void *value, void *baton)
 327 {
 328         struct common_dir *dir = value;
 329
 330         if (!dir)
 331                 return 0;
 332
 333         if (dir->is_dir && (unmatched[0] == 0 || unmatched[0] == '/'))
 334                 return !dir->exclude;
 335
 336         if (!dir->is_dir && unmatched[0] == 0)
 337                 return !dir->exclude;
 338
 339         return 0;
 340 }
 341
 342 static void update_common_dir(struct strbuf *buf, int git_dir_len,
 343                               const char *common_dir)
 344 {
 345         char *base = buf->buf + git_dir_len;
 346         init_common_trie();
 347         if (trie_find(&common_trie, base, check_common, NULL) > 0)
 348                 replace_dir(buf, git_dir_len, common_dir);
 349 }
 350
 351 void report_linked_checkout_garbage(void)
 352 {
 353         struct strbuf sb = STRBUF_INIT;
 354         const struct common_dir *p;
 355         int len;
 356
 357         if (!the_repository->different_commondir)
 358                 return;
 359         strbuf_addf(&sb, "%s/", get_git_dir());
 360         len = sb.len;
 361         for (p = common_list; p->dirname; p++) {
 362                 const char *path = p->dirname;
 363                 if (p->ignore_garbage)
 364                         continue;
 365                 strbuf_setlen(&sb, len);
 366                 strbuf_addstr(&sb, path);
 367                 if (file_exists(sb.buf))
 368                         report_garbage(PACKDIR_FILE_GARBAGE, sb.buf);
 369         }
 370         strbuf_release(&sb);
 371 }
 372
 373 static void adjust_git_path(const struct repository *repo,
 374                             struct strbuf *buf, int git_dir_len)
 375 {
 376         const char *base = buf->buf + git_dir_len;
 377         if (is_dir_file(base, "info", "grafts"))
 378                 strbuf_splice(buf, 0, buf->len,
 379                               repo->graft_file, strlen(repo->graft_file));
 380         else if (!strcmp(base, "index"))
 381                 strbuf_splice(buf, 0, buf->len,
 382                               repo->index_file, strlen(repo->index_file));
 383         else if (dir_prefix(base, "objects"))
 384                 replace_dir(buf, git_dir_len + 7, repo->objectdir);
 385         else if (git_hooks_path && dir_prefix(base, "hooks"))
 386                 replace_dir(buf, git_dir_len + 5, git_hooks_path);
 387         else if (repo->different_commondir)
 388                 update_common_dir(buf, git_dir_len, repo->commondir);
 389 }
 390
 391 static void strbuf_worktree_gitdir(struct strbuf *buf,
 392                                    const struct repository *repo,
 393                                    const struct worktree *wt)
 394 {
 395         if (!wt)
 396                 strbuf_addstr(buf, repo->gitdir);
 397         else if (!wt->id)
 398                 strbuf_addstr(buf, repo->commondir);
 399         else
 400                 strbuf_git_common_path(buf, repo, "worktrees/%s", wt->id);
 401 }
 402
 403 static void do_git_path(const struct repository *repo,
 404                         const struct worktree *wt, struct strbuf *buf,
 405                         const char *fmt, va_list args)
 406 {
 407         int gitdir_len;
 408         strbuf_worktree_gitdir(buf, repo, wt);
 409         if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 410                 strbuf_addch(buf, '/');
 411         gitdir_len = buf->len;
 412         strbuf_vaddf(buf, fmt, args);
 413         if (!wt)
 414                 adjust_git_path(repo, buf, gitdir_len);
 415         strbuf_cleanup_path(buf);
 416 }
 417
 418 char *repo_git_path(const struct repository *repo,
 419                     const char *fmt, ...)
 420 {
 421         struct strbuf path = STRBUF_INIT;
 422         va_list args;
 423         va_start(args, fmt);
 424         do_git_path(repo, NULL, &path, fmt, args);
 425         va_end(args);
 426         return strbuf_detach(&path, NULL);
 427 }
 428
 429 void strbuf_repo_git_path(struct strbuf *sb,
 430                           const struct repository *repo,
 431                           const char *fmt, ...)
 432 {
 433         va_list args;
 434         va_start(args, fmt);
 435         do_git_path(repo, NULL, sb, fmt, args);
 436         va_end(args);
 437 }
 438
 439 char *git_path_buf(struct strbuf *buf, const char *fmt, ...)
 440 {
 441         va_list args;
 442         strbuf_reset(buf);
 443         va_start(args, fmt);
 444         do_git_path(the_repository, NULL, buf, fmt, args);
 445         va_end(args);
 446         return buf->buf;
 447 }
 448
 449 void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 450 {
 451         va_list args;
 452         va_start(args, fmt);
 453         do_git_path(the_repository, NULL, sb, fmt, args);
 454         va_end(args);
 455 }
 456
 457 const char *git_path(const char *fmt, ...)
 458 {
 459         struct strbuf *pathname = get_pathname();
 460         va_list args;
 461         va_start(args, fmt);
 462         do_git_path(the_repository, NULL, pathname, fmt, args);
 463         va_end(args);
 464         return pathname->buf;
 465 }
 466
 467 char *git_pathdup(const char *fmt, ...)
 468 {
 469         struct strbuf path = STRBUF_INIT;
 470         va_list args;
 471         va_start(args, fmt);
 472         do_git_path(the_repository, NULL, &path, fmt, args);
 473         va_end(args);
 474         return strbuf_detach(&path, NULL);
 475 }
 476
 477 char *mkpathdup(const char *fmt, ...)
 478 {
 479         struct strbuf sb = STRBUF_INIT;
 480         va_list args;
 481         va_start(args, fmt);
 482         strbuf_vaddf(&sb, fmt, args);
 483         va_end(args);
 484         strbuf_cleanup_path(&sb);
 485         return strbuf_detach(&sb, NULL);
 486 }
 487
 488 const char *mkpath(const char *fmt, ...)
 489 {
 490         va_list args;
 491         struct strbuf *pathname = get_pathname();
 492         va_start(args, fmt);
 493         strbuf_vaddf(pathname, fmt, args);
 494         va_end(args);
 495         return cleanup_path(pathname->buf);
 496 }
 497
 498 const char *worktree_git_path(const struct worktree *wt, const char *fmt, ...)
 499 {
 500         struct strbuf *pathname = get_pathname();
 501         va_list args;
 502         va_start(args, fmt);
 503         do_git_path(the_repository, wt, pathname, fmt, args);
 504         va_end(args);
 505         return pathname->buf;
 506 }
 507
 508 static void do_worktree_path(const struct repository *repo,
 509                              struct strbuf *buf,
 510                              const char *fmt, va_list args)
 511 {
 512         strbuf_addstr(buf, repo->worktree);
 513         if(buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 514                 strbuf_addch(buf, '/');
 515
 516         strbuf_vaddf(buf, fmt, args);
 517         strbuf_cleanup_path(buf);
 518 }
 519
 520 char *repo_worktree_path(const struct repository *repo, const char *fmt, ...)
 521 {
 522         struct strbuf path = STRBUF_INIT;
 523         va_list args;
 524
 525         if (!repo->worktree)
 526                 return NULL;
 527
 528         va_start(args, fmt);
 529         do_worktree_path(repo, &path, fmt, args);
 530         va_end(args);
 531
 532         return strbuf_detach(&path, NULL);
 533 }
 534
 535 void strbuf_repo_worktree_path(struct strbuf *sb,
 536                                const struct repository *repo,
 537                                const char *fmt, ...)
 538 {
 539         va_list args;
 540
 541         if (!repo->worktree)
 542                 return;
 543
 544         va_start(args, fmt);
 545         do_worktree_path(repo, sb, fmt, args);
 546         va_end(args);
 547 }
 548
 549 /* Returns 0 on success, negative on failure. */
 550 static int do_submodule_path(struct strbuf *buf, const char *path,
 551                              const char *fmt, va_list args)
 552 {
 553         struct strbuf git_submodule_common_dir = STRBUF_INIT;
 554         struct strbuf git_submodule_dir = STRBUF_INIT;
 555         int ret;
 556
 557         ret = submodule_to_gitdir(&git_submodule_dir, path);
 558         if (ret)
 559                 goto cleanup;
 560
 561         strbuf_complete(&git_submodule_dir, '/');
 562         strbuf_addbuf(buf, &git_submodule_dir);
 563         strbuf_vaddf(buf, fmt, args);
 564
 565         if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
 566                 update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);
 567
 568         strbuf_cleanup_path(buf);
 569
 570 cleanup:
 571         strbuf_release(&git_submodule_dir);
 572         strbuf_release(&git_submodule_common_dir);
 573         return ret;
 574 }
 575
 576 char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 577 {
 578         int err;
 579         va_list args;
 580         struct strbuf buf = STRBUF_INIT;
 581         va_start(args, fmt);
 582         err = do_submodule_path(&buf, path, fmt, args);
 583         va_end(args);
 584         if (err) {
 585                 strbuf_release(&buf);
 586                 return NULL;
 587         }
 588         return strbuf_detach(&buf, NULL);
 589 }
 590
 591 int strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 592                               const char *fmt, ...)
 593 {
 594         int err;
 595         va_list args;
 596         va_start(args, fmt);
 597         err = do_submodule_path(buf, path, fmt, args);
 598         va_end(args);
 599
 600         return err;
 601 }
 602
 603 static void do_git_common_path(const struct repository *repo,
 604                                struct strbuf *buf,
 605                                const char *fmt,
 606                                va_list args)
 607 {
 608         strbuf_addstr(buf, repo->commondir);
 609         if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 610                 strbuf_addch(buf, '/');
 611         strbuf_vaddf(buf, fmt, args);
 612         strbuf_cleanup_path(buf);
 613 }
 614
 615 const char *git_common_path(const char *fmt, ...)
 616 {
 617         struct strbuf *pathname = get_pathname();
 618         va_list args;
 619         va_start(args, fmt);
 620         do_git_common_path(the_repository, pathname, fmt, args);
 621         va_end(args);
 622         return pathname->buf;
 623 }
 624
 625 void strbuf_git_common_path(struct strbuf *sb,
 626                             const struct repository *repo,
 627                             const char *fmt, ...)
 628 {
 629         va_list args;
 630         va_start(args, fmt);
 631         do_git_common_path(repo, sb, fmt, args);
 632         va_end(args);
 633 }
 634
 635 int validate_headref(const char *path)
 636 {
 637         struct stat st;
 638         char *buf, buffer[256];
 639         unsigned char sha1[20];
 640         int fd;
 641         ssize_t len;
 642
 643         if (lstat(path, &st) < 0)
 644                 return -1;
 645
 646         /* Make sure it is a "refs/.." symlink */
 647         if (S_ISLNK(st.st_mode)) {
 648                 len = readlink(path, buffer, sizeof(buffer)-1);
 649                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 650                         return 0;
 651                 return -1;
 652         }
 653
 654         /*
 655          * Anything else, just open it and try to see if it is a symbolic ref.
 656          */
 657         fd = open(path, O_RDONLY);
 658         if (fd < 0)
 659                 return -1;
 660         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 661         close(fd);
 662
 663         /*
 664          * Is it a symbolic ref?
 665          */
 666         if (len < 4)
 667                 return -1;
 668         if (!memcmp("ref:", buffer, 4)) {
 669                 buf = buffer + 4;
 670                 len -= 4;
 671                 while (len && isspace(*buf))
 672                         buf++, len--;
 673                 if (len >= 5 && !memcmp("refs/", buf, 5))
 674                         return 0;
 675         }
 676
 677         /*
 678          * Is this a detached HEAD?
 679          */
 680         if (!get_sha1_hex(buffer, sha1))
 681                 return 0;
 682
 683         return -1;
 684 }
 685
 686 static struct passwd *getpw_str(const char *username, size_t len)
 687 {
 688         struct passwd *pw;
 689         char *username_z = xmemdupz(username, len);
 690         pw = getpwnam(username_z);
 691         free(username_z);
 692         return pw;
 693 }
 694
 695 /*
 696  * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 697  * then it is a newly allocated string. Returns NULL on getpw failure or
 698  * if path is NULL.
 699  *
 700  * If real_home is true, real_path($HOME) is used in the expansion.
 701  */
 702 char *expand_user_path(const char *path, int real_home)
 703 {
 704         struct strbuf user_path = STRBUF_INIT;
 705         const char *to_copy = path;
 706
 707         if (path == NULL)
 708                 goto return_null;
 709         if (path[0] == '~') {
 710                 const char *first_slash = strchrnul(path, '/');
 711                 const char *username = path + 1;
 712                 size_t username_len = first_slash - username;
 713                 if (username_len == 0) {
 714                         const char *home = getenv("HOME");
 715                         if (!home)
 716                                 goto return_null;
 717                         if (real_home)
 718                                 strbuf_addstr(&user_path, real_path(home));
 719                         else
 720                                 strbuf_addstr(&user_path, home);
 721 #ifdef GIT_WINDOWS_NATIVE
 722                         convert_slashes(user_path.buf);
 723 #endif
 724                 } else {
 725                         struct passwd *pw = getpw_str(username, username_len);
 726                         if (!pw)
 727                                 goto return_null;
 728                         strbuf_addstr(&user_path, pw->pw_dir);
 729                 }
 730                 to_copy = first_slash;
 731         }
 732         strbuf_addstr(&user_path, to_copy);
 733         return strbuf_detach(&user_path, NULL);
 734 return_null:
 735         strbuf_release(&user_path);
 736         return NULL;
 737 }
 738
 739 /*
 740  * First, one directory to try is determined by the following algorithm.
 741  *
 742  * (0) If "strict" is given, the path is used as given and no DWIM is
 743  *     done. Otherwise:
 744  * (1) "~/path" to mean path under the running user's home directory;
 745  * (2) "~user/path" to mean path under named user's home directory;
 746  * (3) "relative/path" to mean cwd relative directory; or
 747  * (4) "/absolute/path" to mean absolute directory.
 748  *
 749  * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 750  * in this order. We select the first one that is a valid git repository, and
 751  * chdir() to it. If none match, or we fail to chdir, we return NULL.
 752  *
 753  * If all goes well, we return the directory we used to chdir() (but
 754  * before ~user is expanded), avoiding getcwd() resolving symbolic
 755  * links.  User relative paths are also returned as they are given,
 756  * except DWIM suffixing.
 757  */
 758 const char *enter_repo(const char *path, int strict)
 759 {
 760         static struct strbuf validated_path = STRBUF_INIT;
 761         static struct strbuf used_path = STRBUF_INIT;
 762
 763         if (!path)
 764                 return NULL;
 765
 766         if (!strict) {
 767                 static const char *suffix[] = {
 768                         "/.git", "", ".git/.git", ".git", NULL,
 769                 };
 770                 const char *gitfile;
 771                 int len = strlen(path);
 772                 int i;
 773                 while ((1 < len) && (path[len-1] == '/'))
 774                         len--;
 775
 776                 /*
 777                  * We can handle arbitrary-sized buffers, but this remains as a
 778                  * sanity check on untrusted input.
 779                  */
 780                 if (PATH_MAX <= len)
 781                         return NULL;
 782
 783                 strbuf_reset(&used_path);
 784                 strbuf_reset(&validated_path);
 785                 strbuf_add(&used_path, path, len);
 786                 strbuf_add(&validated_path, path, len);
 787
 788                 if (used_path.buf[0] == '~') {
 789                         char *newpath = expand_user_path(used_path.buf, 0);
 790                         if (!newpath)
 791                                 return NULL;
 792                         strbuf_attach(&used_path, newpath, strlen(newpath),
 793                                       strlen(newpath));
 794                 }
 795                 for (i = 0; suffix[i]; i++) {
 796                         struct stat st;
 797                         size_t baselen = used_path.len;
 798                         strbuf_addstr(&used_path, suffix[i]);
 799                         if (!stat(used_path.buf, &st) &&
 800                             (S_ISREG(st.st_mode) ||
 801                             (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
 802                                 strbuf_addstr(&validated_path, suffix[i]);
 803                                 break;
 804                         }
 805                         strbuf_setlen(&used_path, baselen);
 806                 }
 807                 if (!suffix[i])
 808                         return NULL;
 809                 gitfile = read_gitfile(used_path.buf);
 810                 if (gitfile) {
 811                         strbuf_reset(&used_path);
 812                         strbuf_addstr(&used_path, gitfile);
 813                 }
 814                 if (chdir(used_path.buf))
 815                         return NULL;
 816                 path = validated_path.buf;
 817         }
 818         else {
 819                 const char *gitfile = read_gitfile(path);
 820                 if (gitfile)
 821                         path = gitfile;
 822                 if (chdir(path))
 823                         return NULL;
 824         }
 825
 826         if (is_git_directory(".")) {
 827                 set_git_dir(".");
 828                 check_repository_format();
 829                 return path;
 830         }
 831
 832         return NULL;
 833 }
 834
 835 static int calc_shared_perm(int mode)
 836 {
 837         int tweak;
 838
 839         if (get_shared_repository() < 0)
 840                 tweak = -get_shared_repository();
 841         else
 842                 tweak = get_shared_repository();
 843
 844         if (!(mode & S_IWUSR))
 845                 tweak &= ~0222;
 846         if (mode & S_IXUSR)
 847                 /* Copy read bits to execute bits */
 848                 tweak |= (tweak & 0444) >> 2;
 849         if (get_shared_repository() < 0)
 850                 mode = (mode & ~0777) | tweak;
 851         else
 852                 mode |= tweak;
 853
 854         return mode;
 855 }
 856
 857
 858 int adjust_shared_perm(const char *path)
 859 {
 860         int old_mode, new_mode;
 861
 862         if (!get_shared_repository())
 863                 return 0;
 864         if (get_st_mode_bits(path, &old_mode) < 0)
 865                 return -1;
 866
 867         new_mode = calc_shared_perm(old_mode);
 868         if (S_ISDIR(old_mode)) {
 869                 /* Copy read bits to execute bits */
 870                 new_mode |= (new_mode & 0444) >> 2;
 871                 new_mode |= FORCE_DIR_SET_GID;
 872         }
 873
 874         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 875                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 876                 return -2;
 877         return 0;
 878 }
 879
 880 void safe_create_dir(const char *dir, int share)
 881 {
 882         if (mkdir(dir, 0777) < 0) {
 883                 if (errno != EEXIST) {
 884                         perror(dir);
 885                         exit(1);
 886                 }
 887         }
 888         else if (share && adjust_shared_perm(dir))
 889                 die(_("Could not make %s writable by group"), dir);
 890 }
 891
 892 static int have_same_root(const char *path1, const char *path2)
 893 {
 894         int is_abs1, is_abs2;
 895
 896         is_abs1 = is_absolute_path(path1);
 897         is_abs2 = is_absolute_path(path2);
 898         return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 899                (!is_abs1 && !is_abs2);
 900 }
 901
 902 /*
 903  * Give path as relative to prefix.
 904  *
 905  * The strbuf may or may not be used, so do not assume it contains the
 906  * returned path.
 907  */
 908 const char *relative_path(const char *in, const char *prefix,
 909                           struct strbuf *sb)
 910 {
 911         int in_len = in ? strlen(in) : 0;
 912         int prefix_len = prefix ? strlen(prefix) : 0;
 913         int in_off = 0;
 914         int prefix_off = 0;
 915         int i = 0, j = 0;
 916
 917         if (!in_len)
 918                 return "./";
 919         else if (!prefix_len)
 920                 return in;
 921
 922         if (have_same_root(in, prefix))
 923                 /* bypass dos_drive, for "c:" is identical to "C:" */
 924                 i = j = has_dos_drive_prefix(in);
 925         else {
 926                 return in;
 927         }
 928
 929         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 930                 if (is_dir_sep(prefix[i])) {
 931                         while (is_dir_sep(prefix[i]))
 932                                 i++;
 933                         while (is_dir_sep(in[j]))
 934                                 j++;
 935                         prefix_off = i;
 936                         in_off = j;
 937                 } else {
 938                         i++;
 939                         j++;
 940                 }
 941         }
 942
 943         if (
 944             /* "prefix" seems like prefix of "in" */
 945             i >= prefix_len &&
 946             /*
 947              * but "/foo" is not a prefix of "/foobar"
 948              * (i.e. prefix not end with '/')
 949              */
 950             prefix_off < prefix_len) {
 951                 if (j >= in_len) {
 952                         /* in="/a/b", prefix="/a/b" */
 953                         in_off = in_len;
 954                 } else if (is_dir_sep(in[j])) {
 955                         /* in="/a/b/c", prefix="/a/b" */
 956                         while (is_dir_sep(in[j]))
 957                                 j++;
 958                         in_off = j;
 959                 } else {
 960                         /* in="/a/bbb/c", prefix="/a/b" */
 961                         i = prefix_off;
 962                 }
 963         } else if (
 964                    /* "in" is short than "prefix" */
 965                    j >= in_len &&
 966                    /* "in" not end with '/' */
 967                    in_off < in_len) {
 968                 if (is_dir_sep(prefix[i])) {
 969                         /* in="/a/b", prefix="/a/b/c/" */
 970                         while (is_dir_sep(prefix[i]))
 971                                 i++;
 972                         in_off = in_len;
 973                 }
 974         }
 975         in += in_off;
 976         in_len -= in_off;
 977
 978         if (i >= prefix_len) {
 979                 if (!in_len)
 980                         return "./";
 981                 else
 982                         return in;
 983         }
 984
 985         strbuf_reset(sb);
 986         strbuf_grow(sb, in_len);
 987
 988         while (i < prefix_len) {
 989                 if (is_dir_sep(prefix[i])) {
 990                         strbuf_addstr(sb, "../");
 991                         while (is_dir_sep(prefix[i]))
 992                                 i++;
 993                         continue;
 994                 }
 995                 i++;
 996         }
 997         if (!is_dir_sep(prefix[prefix_len - 1]))
 998                 strbuf_addstr(sb, "../");
 999
1000         strbuf_addstr(sb, in);
1001
1002         return sb->buf;
1003 }
1004
1005 /*
1006  * A simpler implementation of relative_path
1007  *
1008  * Get relative path by removing "prefix" from "in". This function
1009  * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
1010  * to increase performance when traversing the path to work_tree.
1011  */
1012 const char *remove_leading_path(const char *in, const char *prefix)
1013 {
1014         static struct strbuf buf = STRBUF_INIT;
1015         int i = 0, j = 0;
1016
1017         if (!prefix || !prefix[0])
1018                 return in;
1019         while (prefix[i]) {
1020                 if (is_dir_sep(prefix[i])) {
1021                         if (!is_dir_sep(in[j]))
1022                                 return in;
1023                         while (is_dir_sep(prefix[i]))
1024                                 i++;
1025                         while (is_dir_sep(in[j]))
1026                                 j++;
1027                         continue;
1028                 } else if (in[j] != prefix[i]) {
1029                         return in;
1030                 }
1031                 i++;
1032                 j++;
1033         }
1034         if (
1035             /* "/foo" is a prefix of "/foo" */
1036             in[j] &&
1037             /* "/foo" is not a prefix of "/foobar" */
1038             !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
1039            )
1040                 return in;
1041         while (is_dir_sep(in[j]))
1042                 j++;
1043
1044         strbuf_reset(&buf);
1045         if (!in[j])
1046                 strbuf_addstr(&buf, ".");
1047         else
1048                 strbuf_addstr(&buf, in + j);
1049         return buf.buf;
1050 }
1051
1052 /*
1053  * It is okay if dst == src, but they should not overlap otherwise.
1054  *
1055  * Performs the following normalizations on src, storing the result in dst:
1056  * - Ensures that components are separated by '/' (Windows only)
1057  * - Squashes sequences of '/' except "//server/share" on Windows
1058  * - Removes "." components.
1059  * - Removes ".." components, and the components the precede them.
1060  * Returns failure (non-zero) if a ".." component appears as first path
1061  * component anytime during the normalization. Otherwise, returns success (0).
1062  *
1063  * Note that this function is purely textual.  It does not follow symlinks,
1064  * verify the existence of the path, or make any system calls.
1065  *
1066  * prefix_len != NULL is for a specific case of prefix_pathspec():
1067  * assume that src == dst and src[0..prefix_len-1] is already
1068  * normalized, any time "../" eats up to the prefix_len part,
1069  * prefix_len is reduced. In the end prefix_len is the remaining
1070  * prefix that has not been overridden by user pathspec.
1071  *
1072  * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
1073  * For everything but the root folder itself, the normalized path should not
1074  * end with a '/', then the callers need to be fixed up accordingly.
1075  *
1076  */
1077 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
1078 {
1079         char *dst0;
1080         const char *end;
1081
1082         /*
1083          * Copy initial part of absolute path: "/", "C:/", "//server/share/".
1084          */
1085         end = src + offset_1st_component(src);
1086         while (src < end) {
1087                 char c = *src++;
1088                 if (is_dir_sep(c))
1089                         c = '/';
1090                 *dst++ = c;
1091         }
1092         dst0 = dst;
1093
1094         while (is_dir_sep(*src))
1095                 src++;
1096
1097         for (;;) {
1098                 char c = *src;
1099
1100                 /*
1101                  * A path component that begins with . could be
1102                  * special:
1103                  * (1) "." and ends   -- ignore and terminate.
1104                  * (2) "./"           -- ignore them, eat slash and continue.
1105                  * (3) ".." and ends  -- strip one and terminate.
1106                  * (4) "../"          -- strip one, eat slash and continue.
1107                  */
1108                 if (c == '.') {
1109                         if (!src[1]) {
1110                                 /* (1) */
1111                                 src++;
1112                         } else if (is_dir_sep(src[1])) {
1113                                 /* (2) */
1114                                 src += 2;
1115                                 while (is_dir_sep(*src))
1116                                         src++;
1117                                 continue;
1118                         } else if (src[1] == '.') {
1119                                 if (!src[2]) {
1120                                         /* (3) */
1121                                         src += 2;
1122                                         goto up_one;
1123                                 } else if (is_dir_sep(src[2])) {
1124                                         /* (4) */
1125                                         src += 3;
1126                                         while (is_dir_sep(*src))
1127                                                 src++;
1128                                         goto up_one;
1129                                 }
1130                         }
1131                 }
1132
1133                 /* copy up to the next '/', and eat all '/' */
1134                 while ((c = *src++) != '\0' && !is_dir_sep(c))
1135                         *dst++ = c;
1136                 if (is_dir_sep(c)) {
1137                         *dst++ = '/';
1138                         while (is_dir_sep(c))
1139                                 c = *src++;
1140                         src--;
1141                 } else if (!c)
1142                         break;
1143                 continue;
1144
1145         up_one:
1146                 /*
1147                  * dst0..dst is prefix portion, and dst[-1] is '/';
1148                  * go up one level.
1149                  */
1150                 dst--;  /* go to trailing '/' */
1151                 if (dst <= dst0)
1152                         return -1;
1153                 /* Windows: dst[-1] cannot be backslash anymore */
1154                 while (dst0 < dst && dst[-1] != '/')
1155                         dst--;
1156                 if (prefix_len && *prefix_len > dst - dst0)
1157                         *prefix_len = dst - dst0;
1158         }
1159         *dst = '\0';
1160         return 0;
1161 }
1162
1163 int normalize_path_copy(char *dst, const char *src)
1164 {
1165         return normalize_path_copy_len(dst, src, NULL);
1166 }
1167
1168 /*
1169  * path = Canonical absolute path
1170  * prefixes = string_list containing normalized, absolute paths without
1171  * trailing slashes (except for the root directory, which is denoted by "/").
1172  *
1173  * Determines, for each path in prefixes, whether the "prefix"
1174  * is an ancestor directory of path.  Returns the length of the longest
1175  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
1176  * is an ancestor.  (Note that this means 0 is returned if prefixes is
1177  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
1178  * are not considered to be their own ancestors.  path must be in a
1179  * canonical form: empty components, or "." or ".." components are not
1180  * allowed.
1181  */
1182 int longest_ancestor_length(const char *path, struct string_list *prefixes)
1183 {
1184         int i, max_len = -1;
1185
1186         if (!strcmp(path, "/"))
1187                 return -1;
1188
1189         for (i = 0; i < prefixes->nr; i++) {
1190                 const char *ceil = prefixes->items[i].string;
1191                 int len = strlen(ceil);
1192
1193                 if (len == 1 && ceil[0] == '/')
1194                         len = 0; /* root matches anything, with length 0 */
1195                 else if (!strncmp(path, ceil, len) && path[len] == '/')
1196                         ; /* match of length len */
1197                 else
1198                         continue; /* no match */
1199
1200                 if (len > max_len)
1201                         max_len = len;
1202         }
1203
1204         return max_len;
1205 }
1206
1207 /* strip arbitrary amount of directory separators at end of path */
1208 static inline int chomp_trailing_dir_sep(const char *path, int len)
1209 {
1210         while (len && is_dir_sep(path[len - 1]))
1211                 len--;
1212         return len;
1213 }
1214
1215 /*
1216  * If path ends with suffix (complete path components), returns the
1217  * part before suffix (sans trailing directory separators).
1218  * Otherwise returns NULL.
1219  */
1220 char *strip_path_suffix(const char *path, const char *suffix)
1221 {
1222         int path_len = strlen(path), suffix_len = strlen(suffix);
1223
1224         while (suffix_len) {
1225                 if (!path_len)
1226                         return NULL;
1227
1228                 if (is_dir_sep(path[path_len - 1])) {
1229                         if (!is_dir_sep(suffix[suffix_len - 1]))
1230                                 return NULL;
1231                         path_len = chomp_trailing_dir_sep(path, path_len);
1232                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
1233                 }
1234                 else if (path[--path_len] != suffix[--suffix_len])
1235                         return NULL;
1236         }
1237
1238         if (path_len && !is_dir_sep(path[path_len - 1]))
1239                 return NULL;
1240         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
1241 }
1242
1243 int daemon_avoid_alias(const char *p)
1244 {
1245         int sl, ndot;
1246
1247         /*
1248          * This resurrects the belts and suspenders paranoia check by HPA
1249          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
1250          * does not do getcwd() based path canonicalization.
1251          *
1252          * sl becomes true immediately after seeing '/' and continues to
1253          * be true as long as dots continue after that without intervening
1254          * non-dot character.
1255          */
1256         if (!p || (*p != '/' && *p != '~'))
1257                 return -1;
1258         sl = 1; ndot = 0;
1259         p++;
1260
1261         while (1) {
1262                 char ch = *p++;
1263                 if (sl) {
1264                         if (ch == '.')
1265                                 ndot++;
1266                         else if (ch == '/') {
1267                                 if (ndot < 3)
1268                                         /* reject //, /./ and /../ */
1269                                         return -1;
1270                                 ndot = 0;
1271                         }
1272                         else if (ch == 0) {
1273                                 if (0 < ndot && ndot < 3)
1274                                         /* reject /.$ and /..$ */
1275                                         return -1;
1276                                 return 0;
1277                         }
1278                         else
1279                                 sl = ndot = 0;
1280                 }
1281                 else if (ch == 0)
1282                         return 0;
1283                 else if (ch == '/') {
1284                         sl = 1;
1285                         ndot = 0;
1286                 }
1287         }
1288 }
1289
1290 static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
1291 {
1292         if (len < skip)
1293                 return 0;
1294         len -= skip;
1295         path += skip;
1296         while (len-- > 0) {
1297                 char c = *(path++);
1298                 if (c != ' ' && c != '.')
1299                         return 0;
1300         }
1301         return 1;
1302 }
1303
1304 int is_ntfs_dotgit(const char *name)
1305 {
1306         int len;
1307
1308         for (len = 0; ; len++)
1309                 if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
1310                         if (only_spaces_and_periods(name, len, 4) &&
1311                                         !strncasecmp(name, ".git", 4))
1312                                 return 1;
1313                         if (only_spaces_and_periods(name, len, 5) &&
1314                                         !strncasecmp(name, "git~1", 5))
1315                                 return 1;
1316                         if (name[len] != '\\')
1317                                 return 0;
1318                         name += len + 1;
1319                         len = -1;
1320                 }
1321 }
1322
1323 int looks_like_command_line_option(const char *str)
1324 {
1325         return str && str[0] == '-';
1326 }
1327
1328 char *xdg_config_home(const char *filename)
1329 {
1330         const char *home, *config_home;
1331
1332         assert(filename);
1333         config_home = getenv("XDG_CONFIG_HOME");
1334         if (config_home && *config_home)
1335                 return mkpathdup("%s/git/%s", config_home, filename);
1336
1337         home = getenv("HOME");
1338         if (home)
1339                 return mkpathdup("%s/.config/git/%s", home, filename);
1340         return NULL;
1341 }
1342
1343 char *xdg_cache_home(const char *filename)
1344 {
1345         const char *home, *cache_home;
1346
1347         assert(filename);
1348         cache_home = getenv("XDG_CACHE_HOME");
1349         if (cache_home && *cache_home)
1350                 return mkpathdup("%s/git/%s", cache_home, filename);
1351
1352         home = getenv("HOME");
1353         if (home)
1354                 return mkpathdup("%s/.cache/git/%s", home, filename);
1355         return NULL;
1356 }
1357
1358 GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
1359 GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
1360 GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
1361 GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
1362 GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
1363 GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
1364 GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
1365 GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
1366 GIT_PATH_FUNC(git_path_shallow, "shallow")