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 char *cleanup_path(char *path)
  37 {
  38         /* Clean it up */
  39         if (!memcmp(path, "./", 2)) {
  40                 path += 2;
  41                 while (*path == '/')
  42                         path++;
  43         }
  44         return path;
  45 }
  46
  47 static void strbuf_cleanup_path(struct strbuf *sb)
  48 {
  49         char *path = cleanup_path(sb->buf);
  50         if (path > sb->buf)
  51                 strbuf_remove(sb, 0, path - sb->buf);
  52 }
  53
  54 char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  55 {
  56         va_list args;
  57         unsigned len;
  58
  59         va_start(args, fmt);
  60         len = vsnprintf(buf, n, fmt, args);
  61         va_end(args);
  62         if (len >= n) {
  63                 strlcpy(buf, bad_path, n);
  64                 return buf;
  65         }
  66         return cleanup_path(buf);
  67 }
  68
  69 static int dir_prefix(const char *buf, const char *dir)
  70 {
  71         int len = strlen(dir);
  72         return !strncmp(buf, dir, len) &&
  73                 (is_dir_sep(buf[len]) || buf[len] == '\0');
  74 }
  75
  76 /* $buf =~ m|$dir/+$file| but without regex */
  77 static int is_dir_file(const char *buf, const char *dir, const char *file)
  78 {
  79         int len = strlen(dir);
  80         if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
  81                 return 0;
  82         while (is_dir_sep(buf[len]))
  83                 len++;
  84         return !strcmp(buf + len, file);
  85 }
  86
  87 static void replace_dir(struct strbuf *buf, int len, const char *newdir)
  88 {
  89         int newlen = strlen(newdir);
  90         int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
  91                 !is_dir_sep(newdir[newlen - 1]);
  92         if (need_sep)
  93                 len--;   /* keep one char, to be replaced with '/'  */
  94         strbuf_splice(buf, 0, len, newdir, newlen);
  95         if (need_sep)
  96                 buf->buf[newlen] = '/';
  97 }
  98
  99 struct common_dir {
 100         /* Not considered garbage for report_linked_checkout_garbage */
 101         unsigned ignore_garbage:1;
 102         unsigned is_dir:1;
 103         /* Not common even though its parent is */
 104         unsigned exclude:1;
 105         const char *dirname;
 106 };
 107
 108 static struct common_dir common_list[] = {
 109         { 0, 1, 0, "branches" },
 110         { 0, 1, 0, "hooks" },
 111         { 0, 1, 0, "info" },
 112         { 0, 0, 1, "info/sparse-checkout" },
 113         { 1, 1, 0, "logs" },
 114         { 1, 1, 1, "logs/HEAD" },
 115         { 0, 1, 1, "logs/refs/bisect" },
 116         { 0, 1, 0, "lost-found" },
 117         { 0, 1, 0, "objects" },
 118         { 0, 1, 0, "refs" },
 119         { 0, 1, 1, "refs/bisect" },
 120         { 0, 1, 0, "remotes" },
 121         { 0, 1, 0, "worktrees" },
 122         { 0, 1, 0, "rr-cache" },
 123         { 0, 1, 0, "svn" },
 124         { 0, 0, 0, "config" },
 125         { 1, 0, 0, "gc.pid" },
 126         { 0, 0, 0, "packed-refs" },
 127         { 0, 0, 0, "shallow" },
 128         { 0, 0, 0, NULL }
 129 };
 130
 131 /*
 132  * A compressed trie.  A trie node consists of zero or more characters that
 133  * are common to all elements with this prefix, optionally followed by some
 134  * children.  If value is not NULL, the trie node is a terminal node.
 135  *
 136  * For example, consider the following set of strings:
 137  * abc
 138  * def
 139  * definite
 140  * definition
 141  *
 142  * The trie would look like:
 143  * root: len = 0, children a and d non-NULL, value = NULL.
 144  *    a: len = 2, contents = bc, value = (data for "abc")
 145  *    d: len = 2, contents = ef, children i non-NULL, value = (data for "def")
 146  *       i: len = 3, contents = nit, children e and i non-NULL, value = NULL
 147  *           e: len = 0, children all NULL, value = (data for "definite")
 148  *           i: len = 2, contents = on, children all NULL,
 149  *              value = (data for "definition")
 150  */
 151 struct trie {
 152         struct trie *children[256];
 153         int len;
 154         char *contents;
 155         void *value;
 156 };
 157
 158 static struct trie *make_trie_node(const char *key, void *value)
 159 {
 160         struct trie *new_node = xcalloc(1, sizeof(*new_node));
 161         new_node->len = strlen(key);
 162         if (new_node->len) {
 163                 new_node->contents = xmalloc(new_node->len);
 164                 memcpy(new_node->contents, key, new_node->len);
 165         }
 166         new_node->value = value;
 167         return new_node;
 168 }
 169
 170 /*
 171  * Add a key/value pair to a trie.  The key is assumed to be \0-terminated.
 172  * If there was an existing value for this key, return it.
 173  */
 174 static void *add_to_trie(struct trie *root, const char *key, void *value)
 175 {
 176         struct trie *child;
 177         void *old;
 178         int i;
 179
 180         if (!*key) {
 181                 /* we have reached the end of the key */
 182                 old = root->value;
 183                 root->value = value;
 184                 return old;
 185         }
 186
 187         for (i = 0; i < root->len; i++) {
 188                 if (root->contents[i] == key[i])
 189                         continue;
 190
 191                 /*
 192                  * Split this node: child will contain this node's
 193                  * existing children.
 194                  */
 195                 child = malloc(sizeof(*child));
 196                 memcpy(child->children, root->children, sizeof(root->children));
 197
 198                 child->len = root->len - i - 1;
 199                 if (child->len) {
 200                         child->contents = xstrndup(root->contents + i + 1,
 201                                                    child->len);
 202                 }
 203                 child->value = root->value;
 204                 root->value = NULL;
 205                 root->len = i;
 206
 207                 memset(root->children, 0, sizeof(root->children));
 208                 root->children[(unsigned char)root->contents[i]] = child;
 209
 210                 /* This is the newly-added child. */
 211                 root->children[(unsigned char)key[i]] =
 212                         make_trie_node(key + i + 1, value);
 213                 return NULL;
 214         }
 215
 216         /* We have matched the entire compressed section */
 217         if (key[i]) {
 218                 child = root->children[(unsigned char)key[root->len]];
 219                 if (child) {
 220                         return add_to_trie(child, key + root->len + 1, value);
 221                 } else {
 222                         child = make_trie_node(key + root->len + 1, value);
 223                         root->children[(unsigned char)key[root->len]] = child;
 224                         return NULL;
 225                 }
 226         }
 227
 228         old = root->value;
 229         root->value = value;
 230         return old;
 231 }
 232
 233 typedef int (*match_fn)(const char *unmatched, void *data, void *baton);
 234
 235 /*
 236  * Search a trie for some key.  Find the longest /-or-\0-terminated
 237  * prefix of the key for which the trie contains a value.  Call fn
 238  * with the unmatched portion of the key and the found value, and
 239  * return its return value.  If there is no such prefix, return -1.
 240  *
 241  * The key is partially normalized: consecutive slashes are skipped.
 242  *
 243  * For example, consider the trie containing only [refs,
 244  * refs/worktree] (both with values).
 245  *
 246  * | key             | unmatched  | val from node | return value |
 247  * |-----------------|------------|---------------|--------------|
 248  * | a               | not called | n/a           | -1           |
 249  * | refs            | \0         | refs          | as per fn    |
 250  * | refs/           | /          | refs          | as per fn    |
 251  * | refs/w          | /w         | refs          | as per fn    |
 252  * | refs/worktree   | \0         | refs/worktree | as per fn    |
 253  * | refs/worktree/  | /          | refs/worktree | as per fn    |
 254  * | refs/worktree/a | /a         | refs/worktree | as per fn    |
 255  * |-----------------|------------|---------------|--------------|
 256  *
 257  */
 258 static int trie_find(struct trie *root, const char *key, match_fn fn,
 259                      void *baton)
 260 {
 261         int i;
 262         int result;
 263         struct trie *child;
 264
 265         if (!*key) {
 266                 /* we have reached the end of the key */
 267                 if (root->value && !root->len)
 268                         return fn(key, root->value, baton);
 269                 else
 270                         return -1;
 271         }
 272
 273         for (i = 0; i < root->len; i++) {
 274                 /* Partial path normalization: skip consecutive slashes. */
 275                 if (key[i] == '/' && key[i+1] == '/') {
 276                         key++;
 277                         continue;
 278                 }
 279                 if (root->contents[i] != key[i])
 280                         return -1;
 281         }
 282
 283         /* Matched the entire compressed section */
 284         key += i;
 285         if (!*key)
 286                 /* End of key */
 287                 return fn(key, root->value, baton);
 288
 289         /* Partial path normalization: skip consecutive slashes */
 290         while (key[0] == '/' && key[1] == '/')
 291                 key++;
 292
 293         child = root->children[(unsigned char)*key];
 294         if (child)
 295                 result = trie_find(child, key + 1, fn, baton);
 296         else
 297                 result = -1;
 298
 299         if (result >= 0 || (*key != '/' && *key != 0))
 300                 return result;
 301         if (root->value)
 302                 return fn(key, root->value, baton);
 303         else
 304                 return -1;
 305 }
 306
 307 static struct trie common_trie;
 308 static int common_trie_done_setup;
 309
 310 static void init_common_trie(void)
 311 {
 312         struct common_dir *p;
 313
 314         if (common_trie_done_setup)
 315                 return;
 316
 317         for (p = common_list; p->dirname; p++)
 318                 add_to_trie(&common_trie, p->dirname, p);
 319
 320         common_trie_done_setup = 1;
 321 }
 322
 323 /*
 324  * Helper function for update_common_dir: returns 1 if the dir
 325  * prefix is common.
 326  */
 327 static int check_common(const char *unmatched, void *value, void *baton)
 328 {
 329         struct common_dir *dir = value;
 330
 331         if (!dir)
 332                 return 0;
 333
 334         if (dir->is_dir && (unmatched[0] == 0 || unmatched[0] == '/'))
 335                 return !dir->exclude;
 336
 337         if (!dir->is_dir && unmatched[0] == 0)
 338                 return !dir->exclude;
 339
 340         return 0;
 341 }
 342
 343 static void update_common_dir(struct strbuf *buf, int git_dir_len,
 344                               const char *common_dir)
 345 {
 346         char *base = buf->buf + git_dir_len;
 347         init_common_trie();
 348         if (trie_find(&common_trie, base, check_common, NULL) > 0)
 349                 replace_dir(buf, git_dir_len, common_dir);
 350 }
 351
 352 void report_linked_checkout_garbage(void)
 353 {
 354         struct strbuf sb = STRBUF_INIT;
 355         const struct common_dir *p;
 356         int len;
 357
 358         if (!the_repository->different_commondir)
 359                 return;
 360         strbuf_addf(&sb, "%s/", get_git_dir());
 361         len = sb.len;
 362         for (p = common_list; p->dirname; p++) {
 363                 const char *path = p->dirname;
 364                 if (p->ignore_garbage)
 365                         continue;
 366                 strbuf_setlen(&sb, len);
 367                 strbuf_addstr(&sb, path);
 368                 if (file_exists(sb.buf))
 369                         report_garbage(PACKDIR_FILE_GARBAGE, sb.buf);
 370         }
 371         strbuf_release(&sb);
 372 }
 373
 374 static void adjust_git_path(const struct repository *repo,
 375                             struct strbuf *buf, int git_dir_len)
 376 {
 377         const char *base = buf->buf + git_dir_len;
 378         if (is_dir_file(base, "info", "grafts"))
 379                 strbuf_splice(buf, 0, buf->len,
 380                               repo->graft_file, strlen(repo->graft_file));
 381         else if (!strcmp(base, "index"))
 382                 strbuf_splice(buf, 0, buf->len,
 383                               repo->index_file, strlen(repo->index_file));
 384         else if (dir_prefix(base, "objects"))
 385                 replace_dir(buf, git_dir_len + 7, repo->objectdir);
 386         else if (git_hooks_path && dir_prefix(base, "hooks"))
 387                 replace_dir(buf, git_dir_len + 5, git_hooks_path);
 388         else if (repo->different_commondir)
 389                 update_common_dir(buf, git_dir_len, repo->commondir);
 390 }
 391
 392 static void strbuf_worktree_gitdir(struct strbuf *buf,
 393                                    const struct repository *repo,
 394                                    const struct worktree *wt)
 395 {
 396         if (!wt)
 397                 strbuf_addstr(buf, repo->gitdir);
 398         else if (!wt->id)
 399                 strbuf_addstr(buf, repo->commondir);
 400         else
 401                 strbuf_git_common_path(buf, repo, "worktrees/%s", wt->id);
 402 }
 403
 404 static void do_git_path(const struct repository *repo,
 405                         const struct worktree *wt, struct strbuf *buf,
 406                         const char *fmt, va_list args)
 407 {
 408         int gitdir_len;
 409         strbuf_worktree_gitdir(buf, repo, wt);
 410         if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 411                 strbuf_addch(buf, '/');
 412         gitdir_len = buf->len;
 413         strbuf_vaddf(buf, fmt, args);
 414         if (!wt)
 415                 adjust_git_path(repo, buf, gitdir_len);
 416         strbuf_cleanup_path(buf);
 417 }
 418
 419 char *repo_git_path(const struct repository *repo,
 420                     const char *fmt, ...)
 421 {
 422         struct strbuf path = STRBUF_INIT;
 423         va_list args;
 424         va_start(args, fmt);
 425         do_git_path(repo, NULL, &path, fmt, args);
 426         va_end(args);
 427         return strbuf_detach(&path, NULL);
 428 }
 429
 430 void strbuf_repo_git_path(struct strbuf *sb,
 431                           const struct repository *repo,
 432                           const char *fmt, ...)
 433 {
 434         va_list args;
 435         va_start(args, fmt);
 436         do_git_path(repo, NULL, sb, fmt, args);
 437         va_end(args);
 438 }
 439
 440 char *git_path_buf(struct strbuf *buf, const char *fmt, ...)
 441 {
 442         va_list args;
 443         strbuf_reset(buf);
 444         va_start(args, fmt);
 445         do_git_path(the_repository, NULL, buf, fmt, args);
 446         va_end(args);
 447         return buf->buf;
 448 }
 449
 450 void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 451 {
 452         va_list args;
 453         va_start(args, fmt);
 454         do_git_path(the_repository, NULL, sb, fmt, args);
 455         va_end(args);
 456 }
 457
 458 const char *git_path(const char *fmt, ...)
 459 {
 460         struct strbuf *pathname = get_pathname();
 461         va_list args;
 462         va_start(args, fmt);
 463         do_git_path(the_repository, NULL, pathname, fmt, args);
 464         va_end(args);
 465         return pathname->buf;
 466 }
 467
 468 char *git_pathdup(const char *fmt, ...)
 469 {
 470         struct strbuf path = STRBUF_INIT;
 471         va_list args;
 472         va_start(args, fmt);
 473         do_git_path(the_repository, NULL, &path, fmt, args);
 474         va_end(args);
 475         return strbuf_detach(&path, NULL);
 476 }
 477
 478 char *mkpathdup(const char *fmt, ...)
 479 {
 480         struct strbuf sb = STRBUF_INIT;
 481         va_list args;
 482         va_start(args, fmt);
 483         strbuf_vaddf(&sb, fmt, args);
 484         va_end(args);
 485         strbuf_cleanup_path(&sb);
 486         return strbuf_detach(&sb, NULL);
 487 }
 488
 489 const char *mkpath(const char *fmt, ...)
 490 {
 491         va_list args;
 492         struct strbuf *pathname = get_pathname();
 493         va_start(args, fmt);
 494         strbuf_vaddf(pathname, fmt, args);
 495         va_end(args);
 496         return cleanup_path(pathname->buf);
 497 }
 498
 499 const char *worktree_git_path(const struct worktree *wt, const char *fmt, ...)
 500 {
 501         struct strbuf *pathname = get_pathname();
 502         va_list args;
 503         va_start(args, fmt);
 504         do_git_path(the_repository, wt, pathname, fmt, args);
 505         va_end(args);
 506         return pathname->buf;
 507 }
 508
 509 static void do_worktree_path(const struct repository *repo,
 510                              struct strbuf *buf,
 511                              const char *fmt, va_list args)
 512 {
 513         strbuf_addstr(buf, repo->worktree);
 514         if(buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 515                 strbuf_addch(buf, '/');
 516
 517         strbuf_vaddf(buf, fmt, args);
 518         strbuf_cleanup_path(buf);
 519 }
 520
 521 char *repo_worktree_path(const struct repository *repo, const char *fmt, ...)
 522 {
 523         struct strbuf path = STRBUF_INIT;
 524         va_list args;
 525
 526         if (!repo->worktree)
 527                 return NULL;
 528
 529         va_start(args, fmt);
 530         do_worktree_path(repo, &path, fmt, args);
 531         va_end(args);
 532
 533         return strbuf_detach(&path, NULL);
 534 }
 535
 536 void strbuf_repo_worktree_path(struct strbuf *sb,
 537                                const struct repository *repo,
 538                                const char *fmt, ...)
 539 {
 540         va_list args;
 541
 542         if (!repo->worktree)
 543                 return;
 544
 545         va_start(args, fmt);
 546         do_worktree_path(repo, sb, fmt, args);
 547         va_end(args);
 548 }
 549
 550 /* Returns 0 on success, negative on failure. */
 551 static int do_submodule_path(struct strbuf *buf, const char *path,
 552                              const char *fmt, va_list args)
 553 {
 554         struct strbuf git_submodule_common_dir = STRBUF_INIT;
 555         struct strbuf git_submodule_dir = STRBUF_INIT;
 556         int ret;
 557
 558         ret = submodule_to_gitdir(&git_submodule_dir, path);
 559         if (ret)
 560                 goto cleanup;
 561
 562         strbuf_complete(&git_submodule_dir, '/');
 563         strbuf_addbuf(buf, &git_submodule_dir);
 564         strbuf_vaddf(buf, fmt, args);
 565
 566         if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
 567                 update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);
 568
 569         strbuf_cleanup_path(buf);
 570
 571 cleanup:
 572         strbuf_release(&git_submodule_dir);
 573         strbuf_release(&git_submodule_common_dir);
 574         return ret;
 575 }
 576
 577 char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 578 {
 579         int err;
 580         va_list args;
 581         struct strbuf buf = STRBUF_INIT;
 582         va_start(args, fmt);
 583         err = do_submodule_path(&buf, path, fmt, args);
 584         va_end(args);
 585         if (err) {
 586                 strbuf_release(&buf);
 587                 return NULL;
 588         }
 589         return strbuf_detach(&buf, NULL);
 590 }
 591
 592 int strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 593                               const char *fmt, ...)
 594 {
 595         int err;
 596         va_list args;
 597         va_start(args, fmt);
 598         err = do_submodule_path(buf, path, fmt, args);
 599         va_end(args);
 600
 601         return err;
 602 }
 603
 604 static void do_git_common_path(const struct repository *repo,
 605                                struct strbuf *buf,
 606                                const char *fmt,
 607                                va_list args)
 608 {
 609         strbuf_addstr(buf, repo->commondir);
 610         if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 611                 strbuf_addch(buf, '/');
 612         strbuf_vaddf(buf, fmt, args);
 613         strbuf_cleanup_path(buf);
 614 }
 615
 616 const char *git_common_path(const char *fmt, ...)
 617 {
 618         struct strbuf *pathname = get_pathname();
 619         va_list args;
 620         va_start(args, fmt);
 621         do_git_common_path(the_repository, pathname, fmt, args);
 622         va_end(args);
 623         return pathname->buf;
 624 }
 625
 626 void strbuf_git_common_path(struct strbuf *sb,
 627                             const struct repository *repo,
 628                             const char *fmt, ...)
 629 {
 630         va_list args;
 631         va_start(args, fmt);
 632         do_git_common_path(repo, sb, fmt, args);
 633         va_end(args);
 634 }
 635
 636 int validate_headref(const char *path)
 637 {
 638         struct stat st;
 639         char *buf, buffer[256];
 640         unsigned char sha1[20];
 641         int fd;
 642         ssize_t len;
 643
 644         if (lstat(path, &st) < 0)
 645                 return -1;
 646
 647         /* Make sure it is a "refs/.." symlink */
 648         if (S_ISLNK(st.st_mode)) {
 649                 len = readlink(path, buffer, sizeof(buffer)-1);
 650                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 651                         return 0;
 652                 return -1;
 653         }
 654
 655         /*
 656          * Anything else, just open it and try to see if it is a symbolic ref.
 657          */
 658         fd = open(path, O_RDONLY);
 659         if (fd < 0)
 660                 return -1;
 661         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 662         close(fd);
 663
 664         /*
 665          * Is it a symbolic ref?
 666          */
 667         if (len < 4)
 668                 return -1;
 669         if (!memcmp("ref:", buffer, 4)) {
 670                 buf = buffer + 4;
 671                 len -= 4;
 672                 while (len && isspace(*buf))
 673                         buf++, len--;
 674                 if (len >= 5 && !memcmp("refs/", buf, 5))
 675                         return 0;
 676         }
 677
 678         /*
 679          * Is this a detached HEAD?
 680          */
 681         if (!get_sha1_hex(buffer, sha1))
 682                 return 0;
 683
 684         return -1;
 685 }
 686
 687 static struct passwd *getpw_str(const char *username, size_t len)
 688 {
 689         struct passwd *pw;
 690         char *username_z = xmemdupz(username, len);
 691         pw = getpwnam(username_z);
 692         free(username_z);
 693         return pw;
 694 }
 695
 696 /*
 697  * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 698  * then it is a newly allocated string. Returns NULL on getpw failure or
 699  * if path is NULL.
 700  *
 701  * If real_home is true, real_path($HOME) is used in the expansion.
 702  */
 703 char *expand_user_path(const char *path, int real_home)
 704 {
 705         struct strbuf user_path = STRBUF_INIT;
 706         const char *to_copy = path;
 707
 708         if (path == NULL)
 709                 goto return_null;
 710         if (path[0] == '~') {
 711                 const char *first_slash = strchrnul(path, '/');
 712                 const char *username = path + 1;
 713                 size_t username_len = first_slash - username;
 714                 if (username_len == 0) {
 715                         const char *home = getenv("HOME");
 716                         if (!home)
 717                                 goto return_null;
 718                         if (real_home)
 719                                 strbuf_addstr(&user_path, real_path(home));
 720                         else
 721                                 strbuf_addstr(&user_path, home);
 722 #ifdef GIT_WINDOWS_NATIVE
 723                         convert_slashes(user_path.buf);
 724 #endif
 725                 } else {
 726                         struct passwd *pw = getpw_str(username, username_len);
 727                         if (!pw)
 728                                 goto return_null;
 729                         strbuf_addstr(&user_path, pw->pw_dir);
 730                 }
 731                 to_copy = first_slash;
 732         }
 733         strbuf_addstr(&user_path, to_copy);
 734         return strbuf_detach(&user_path, NULL);
 735 return_null:
 736         strbuf_release(&user_path);
 737         return NULL;
 738 }
 739
 740 /*
 741  * First, one directory to try is determined by the following algorithm.
 742  *
 743  * (0) If "strict" is given, the path is used as given and no DWIM is
 744  *     done. Otherwise:
 745  * (1) "~/path" to mean path under the running user's home directory;
 746  * (2) "~user/path" to mean path under named user's home directory;
 747  * (3) "relative/path" to mean cwd relative directory; or
 748  * (4) "/absolute/path" to mean absolute directory.
 749  *
 750  * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 751  * in this order. We select the first one that is a valid git repository, and
 752  * chdir() to it. If none match, or we fail to chdir, we return NULL.
 753  *
 754  * If all goes well, we return the directory we used to chdir() (but
 755  * before ~user is expanded), avoiding getcwd() resolving symbolic
 756  * links.  User relative paths are also returned as they are given,
 757  * except DWIM suffixing.
 758  */
 759 const char *enter_repo(const char *path, int strict)
 760 {
 761         static struct strbuf validated_path = STRBUF_INIT;
 762         static struct strbuf used_path = STRBUF_INIT;
 763
 764         if (!path)
 765                 return NULL;
 766
 767         if (!strict) {
 768                 static const char *suffix[] = {
 769                         "/.git", "", ".git/.git", ".git", NULL,
 770                 };
 771                 const char *gitfile;
 772                 int len = strlen(path);
 773                 int i;
 774                 while ((1 < len) && (path[len-1] == '/'))
 775                         len--;
 776
 777                 /*
 778                  * We can handle arbitrary-sized buffers, but this remains as a
 779                  * sanity check on untrusted input.
 780                  */
 781                 if (PATH_MAX <= len)
 782                         return NULL;
 783
 784                 strbuf_reset(&used_path);
 785                 strbuf_reset(&validated_path);
 786                 strbuf_add(&used_path, path, len);
 787                 strbuf_add(&validated_path, path, len);
 788
 789                 if (used_path.buf[0] == '~') {
 790                         char *newpath = expand_user_path(used_path.buf, 0);
 791                         if (!newpath)
 792                                 return NULL;
 793                         strbuf_attach(&used_path, newpath, strlen(newpath),
 794                                       strlen(newpath));
 795                 }
 796                 for (i = 0; suffix[i]; i++) {
 797                         struct stat st;
 798                         size_t baselen = used_path.len;
 799                         strbuf_addstr(&used_path, suffix[i]);
 800                         if (!stat(used_path.buf, &st) &&
 801                             (S_ISREG(st.st_mode) ||
 802                             (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
 803                                 strbuf_addstr(&validated_path, suffix[i]);
 804                                 break;
 805                         }
 806                         strbuf_setlen(&used_path, baselen);
 807                 }
 808                 if (!suffix[i])
 809                         return NULL;
 810                 gitfile = read_gitfile(used_path.buf);
 811                 if (gitfile) {
 812                         strbuf_reset(&used_path);
 813                         strbuf_addstr(&used_path, gitfile);
 814                 }
 815                 if (chdir(used_path.buf))
 816                         return NULL;
 817                 path = validated_path.buf;
 818         }
 819         else {
 820                 const char *gitfile = read_gitfile(path);
 821                 if (gitfile)
 822                         path = gitfile;
 823                 if (chdir(path))
 824                         return NULL;
 825         }
 826
 827         if (is_git_directory(".")) {
 828                 set_git_dir(".");
 829                 check_repository_format();
 830                 return path;
 831         }
 832
 833         return NULL;
 834 }
 835
 836 static int calc_shared_perm(int mode)
 837 {
 838         int tweak;
 839
 840         if (get_shared_repository() < 0)
 841                 tweak = -get_shared_repository();
 842         else
 843                 tweak = get_shared_repository();
 844
 845         if (!(mode & S_IWUSR))
 846                 tweak &= ~0222;
 847         if (mode & S_IXUSR)
 848                 /* Copy read bits to execute bits */
 849                 tweak |= (tweak & 0444) >> 2;
 850         if (get_shared_repository() < 0)
 851                 mode = (mode & ~0777) | tweak;
 852         else
 853                 mode |= tweak;
 854
 855         return mode;
 856 }
 857
 858
 859 int adjust_shared_perm(const char *path)
 860 {
 861         int old_mode, new_mode;
 862
 863         if (!get_shared_repository())
 864                 return 0;
 865         if (get_st_mode_bits(path, &old_mode) < 0)
 866                 return -1;
 867
 868         new_mode = calc_shared_perm(old_mode);
 869         if (S_ISDIR(old_mode)) {
 870                 /* Copy read bits to execute bits */
 871                 new_mode |= (new_mode & 0444) >> 2;
 872                 new_mode |= FORCE_DIR_SET_GID;
 873         }
 874
 875         if (((old_mode ^ new_mode) & ~S_IFMT) &&
 876                         chmod(path, (new_mode & ~S_IFMT)) < 0)
 877                 return -2;
 878         return 0;
 879 }
 880
 881 void safe_create_dir(const char *dir, int share)
 882 {
 883         if (mkdir(dir, 0777) < 0) {
 884                 if (errno != EEXIST) {
 885                         perror(dir);
 886                         exit(1);
 887                 }
 888         }
 889         else if (share && adjust_shared_perm(dir))
 890                 die(_("Could not make %s writable by group"), dir);
 891 }
 892
 893 static int have_same_root(const char *path1, const char *path2)
 894 {
 895         int is_abs1, is_abs2;
 896
 897         is_abs1 = is_absolute_path(path1);
 898         is_abs2 = is_absolute_path(path2);
 899         return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 900                (!is_abs1 && !is_abs2);
 901 }
 902
 903 /*
 904  * Give path as relative to prefix.
 905  *
 906  * The strbuf may or may not be used, so do not assume it contains the
 907  * returned path.
 908  */
 909 const char *relative_path(const char *in, const char *prefix,
 910                           struct strbuf *sb)
 911 {
 912         int in_len = in ? strlen(in) : 0;
 913         int prefix_len = prefix ? strlen(prefix) : 0;
 914         int in_off = 0;
 915         int prefix_off = 0;
 916         int i = 0, j = 0;
 917
 918         if (!in_len)
 919                 return "./";
 920         else if (!prefix_len)
 921                 return in;
 922
 923         if (have_same_root(in, prefix))
 924                 /* bypass dos_drive, for "c:" is identical to "C:" */
 925                 i = j = has_dos_drive_prefix(in);
 926         else {
 927                 return in;
 928         }
 929
 930         while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 931                 if (is_dir_sep(prefix[i])) {
 932                         while (is_dir_sep(prefix[i]))
 933                                 i++;
 934                         while (is_dir_sep(in[j]))
 935                                 j++;
 936                         prefix_off = i;
 937                         in_off = j;
 938                 } else {
 939                         i++;
 940                         j++;
 941                 }
 942         }
 943
 944         if (
 945             /* "prefix" seems like prefix of "in" */
 946             i >= prefix_len &&
 947             /*
 948              * but "/foo" is not a prefix of "/foobar"
 949              * (i.e. prefix not end with '/')
 950              */
 951             prefix_off < prefix_len) {
 952                 if (j >= in_len) {
 953                         /* in="/a/b", prefix="/a/b" */
 954                         in_off = in_len;
 955                 } else if (is_dir_sep(in[j])) {
 956                         /* in="/a/b/c", prefix="/a/b" */
 957                         while (is_dir_sep(in[j]))
 958                                 j++;
 959                         in_off = j;
 960                 } else {
 961                         /* in="/a/bbb/c", prefix="/a/b" */
 962                         i = prefix_off;
 963                 }
 964         } else if (
 965                    /* "in" is short than "prefix" */
 966                    j >= in_len &&
 967                    /* "in" not end with '/' */
 968                    in_off < in_len) {
 969                 if (is_dir_sep(prefix[i])) {
 970                         /* in="/a/b", prefix="/a/b/c/" */
 971                         while (is_dir_sep(prefix[i]))
 972                                 i++;
 973                         in_off = in_len;
 974                 }
 975         }
 976         in += in_off;
 977         in_len -= in_off;
 978
 979         if (i >= prefix_len) {
 980                 if (!in_len)
 981                         return "./";
 982                 else
 983                         return in;
 984         }
 985
 986         strbuf_reset(sb);
 987         strbuf_grow(sb, in_len);
 988
 989         while (i < prefix_len) {
 990                 if (is_dir_sep(prefix[i])) {
 991                         strbuf_addstr(sb, "../");
 992                         while (is_dir_sep(prefix[i]))
 993                                 i++;
 994                         continue;
 995                 }
 996                 i++;
 997         }
 998         if (!is_dir_sep(prefix[prefix_len - 1]))
 999                 strbuf_addstr(sb, "../");
1000
1001         strbuf_addstr(sb, in);
1002
1003         return sb->buf;
1004 }
1005
1006 /*
1007  * A simpler implementation of relative_path
1008  *
1009  * Get relative path by removing "prefix" from "in". This function
1010  * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
1011  * to increase performance when traversing the path to work_tree.
1012  */
1013 const char *remove_leading_path(const char *in, const char *prefix)
1014 {
1015         static struct strbuf buf = STRBUF_INIT;
1016         int i = 0, j = 0;
1017
1018         if (!prefix || !prefix[0])
1019                 return in;
1020         while (prefix[i]) {
1021                 if (is_dir_sep(prefix[i])) {
1022                         if (!is_dir_sep(in[j]))
1023                                 return in;
1024                         while (is_dir_sep(prefix[i]))
1025                                 i++;
1026                         while (is_dir_sep(in[j]))
1027                                 j++;
1028                         continue;
1029                 } else if (in[j] != prefix[i]) {
1030                         return in;
1031                 }
1032                 i++;
1033                 j++;
1034         }
1035         if (
1036             /* "/foo" is a prefix of "/foo" */
1037             in[j] &&
1038             /* "/foo" is not a prefix of "/foobar" */
1039             !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
1040            )
1041                 return in;
1042         while (is_dir_sep(in[j]))
1043                 j++;
1044
1045         strbuf_reset(&buf);
1046         if (!in[j])
1047                 strbuf_addstr(&buf, ".");
1048         else
1049                 strbuf_addstr(&buf, in + j);
1050         return buf.buf;
1051 }
1052
1053 /*
1054  * It is okay if dst == src, but they should not overlap otherwise.
1055  *
1056  * Performs the following normalizations on src, storing the result in dst:
1057  * - Ensures that components are separated by '/' (Windows only)
1058  * - Squashes sequences of '/' except "//server/share" on Windows
1059  * - Removes "." components.
1060  * - Removes ".." components, and the components the precede them.
1061  * Returns failure (non-zero) if a ".." component appears as first path
1062  * component anytime during the normalization. Otherwise, returns success (0).
1063  *
1064  * Note that this function is purely textual.  It does not follow symlinks,
1065  * verify the existence of the path, or make any system calls.
1066  *
1067  * prefix_len != NULL is for a specific case of prefix_pathspec():
1068  * assume that src == dst and src[0..prefix_len-1] is already
1069  * normalized, any time "../" eats up to the prefix_len part,
1070  * prefix_len is reduced. In the end prefix_len is the remaining
1071  * prefix that has not been overridden by user pathspec.
1072  *
1073  * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
1074  * For everything but the root folder itself, the normalized path should not
1075  * end with a '/', then the callers need to be fixed up accordingly.
1076  *
1077  */
1078 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
1079 {
1080         char *dst0;
1081         const char *end;
1082
1083         /*
1084          * Copy initial part of absolute path: "/", "C:/", "//server/share/".
1085          */
1086         end = src + offset_1st_component(src);
1087         while (src < end) {
1088                 char c = *src++;
1089                 if (is_dir_sep(c))
1090                         c = '/';
1091                 *dst++ = c;
1092         }
1093         dst0 = dst;
1094
1095         while (is_dir_sep(*src))
1096                 src++;
1097
1098         for (;;) {
1099                 char c = *src;
1100
1101                 /*
1102                  * A path component that begins with . could be
1103                  * special:
1104                  * (1) "." and ends   -- ignore and terminate.
1105                  * (2) "./"           -- ignore them, eat slash and continue.
1106                  * (3) ".." and ends  -- strip one and terminate.
1107                  * (4) "../"          -- strip one, eat slash and continue.
1108                  */
1109                 if (c == '.') {
1110                         if (!src[1]) {
1111                                 /* (1) */
1112                                 src++;
1113                         } else if (is_dir_sep(src[1])) {
1114                                 /* (2) */
1115                                 src += 2;
1116                                 while (is_dir_sep(*src))
1117                                         src++;
1118                                 continue;
1119                         } else if (src[1] == '.') {
1120                                 if (!src[2]) {
1121                                         /* (3) */
1122                                         src += 2;
1123                                         goto up_one;
1124                                 } else if (is_dir_sep(src[2])) {
1125                                         /* (4) */
1126                                         src += 3;
1127                                         while (is_dir_sep(*src))
1128                                                 src++;
1129                                         goto up_one;
1130                                 }
1131                         }
1132                 }
1133
1134                 /* copy up to the next '/', and eat all '/' */
1135                 while ((c = *src++) != '\0' && !is_dir_sep(c))
1136                         *dst++ = c;
1137                 if (is_dir_sep(c)) {
1138                         *dst++ = '/';
1139                         while (is_dir_sep(c))
1140                                 c = *src++;
1141                         src--;
1142                 } else if (!c)
1143                         break;
1144                 continue;
1145
1146         up_one:
1147                 /*
1148                  * dst0..dst is prefix portion, and dst[-1] is '/';
1149                  * go up one level.
1150                  */
1151                 dst--;  /* go to trailing '/' */
1152                 if (dst <= dst0)
1153                         return -1;
1154                 /* Windows: dst[-1] cannot be backslash anymore */
1155                 while (dst0 < dst && dst[-1] != '/')
1156                         dst--;
1157                 if (prefix_len && *prefix_len > dst - dst0)
1158                         *prefix_len = dst - dst0;
1159         }
1160         *dst = '\0';
1161         return 0;
1162 }
1163
1164 int normalize_path_copy(char *dst, const char *src)
1165 {
1166         return normalize_path_copy_len(dst, src, NULL);
1167 }
1168
1169 /*
1170  * path = Canonical absolute path
1171  * prefixes = string_list containing normalized, absolute paths without
1172  * trailing slashes (except for the root directory, which is denoted by "/").
1173  *
1174  * Determines, for each path in prefixes, whether the "prefix"
1175  * is an ancestor directory of path.  Returns the length of the longest
1176  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
1177  * is an ancestor.  (Note that this means 0 is returned if prefixes is
1178  * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
1179  * are not considered to be their own ancestors.  path must be in a
1180  * canonical form: empty components, or "." or ".." components are not
1181  * allowed.
1182  */
1183 int longest_ancestor_length(const char *path, struct string_list *prefixes)
1184 {
1185         int i, max_len = -1;
1186
1187         if (!strcmp(path, "/"))
1188                 return -1;
1189
1190         for (i = 0; i < prefixes->nr; i++) {
1191                 const char *ceil = prefixes->items[i].string;
1192                 int len = strlen(ceil);
1193
1194                 if (len == 1 && ceil[0] == '/')
1195                         len = 0; /* root matches anything, with length 0 */
1196                 else if (!strncmp(path, ceil, len) && path[len] == '/')
1197                         ; /* match of length len */
1198                 else
1199                         continue; /* no match */
1200
1201                 if (len > max_len)
1202                         max_len = len;
1203         }
1204
1205         return max_len;
1206 }
1207
1208 /* strip arbitrary amount of directory separators at end of path */
1209 static inline int chomp_trailing_dir_sep(const char *path, int len)
1210 {
1211         while (len && is_dir_sep(path[len - 1]))
1212                 len--;
1213         return len;
1214 }
1215
1216 /*
1217  * If path ends with suffix (complete path components), returns the
1218  * part before suffix (sans trailing directory separators).
1219  * Otherwise returns NULL.
1220  */
1221 char *strip_path_suffix(const char *path, const char *suffix)
1222 {
1223         int path_len = strlen(path), suffix_len = strlen(suffix);
1224
1225         while (suffix_len) {
1226                 if (!path_len)
1227                         return NULL;
1228
1229                 if (is_dir_sep(path[path_len - 1])) {
1230                         if (!is_dir_sep(suffix[suffix_len - 1]))
1231                                 return NULL;
1232                         path_len = chomp_trailing_dir_sep(path, path_len);
1233                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
1234                 }
1235                 else if (path[--path_len] != suffix[--suffix_len])
1236                         return NULL;
1237         }
1238
1239         if (path_len && !is_dir_sep(path[path_len - 1]))
1240                 return NULL;
1241         return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
1242 }
1243
1244 int daemon_avoid_alias(const char *p)
1245 {
1246         int sl, ndot;
1247
1248         /*
1249          * This resurrects the belts and suspenders paranoia check by HPA
1250          * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
1251          * does not do getcwd() based path canonicalization.
1252          *
1253          * sl becomes true immediately after seeing '/' and continues to
1254          * be true as long as dots continue after that without intervening
1255          * non-dot character.
1256          */
1257         if (!p || (*p != '/' && *p != '~'))
1258                 return -1;
1259         sl = 1; ndot = 0;
1260         p++;
1261
1262         while (1) {
1263                 char ch = *p++;
1264                 if (sl) {
1265                         if (ch == '.')
1266                                 ndot++;
1267                         else if (ch == '/') {
1268                                 if (ndot < 3)
1269                                         /* reject //, /./ and /../ */
1270                                         return -1;
1271                                 ndot = 0;
1272                         }
1273                         else if (ch == 0) {
1274                                 if (0 < ndot && ndot < 3)
1275                                         /* reject /.$ and /..$ */
1276                                         return -1;
1277                                 return 0;
1278                         }
1279                         else
1280                                 sl = ndot = 0;
1281                 }
1282                 else if (ch == 0)
1283                         return 0;
1284                 else if (ch == '/') {
1285                         sl = 1;
1286                         ndot = 0;
1287                 }
1288         }
1289 }
1290
1291 static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
1292 {
1293         if (len < skip)
1294                 return 0;
1295         len -= skip;
1296         path += skip;
1297         while (len-- > 0) {
1298                 char c = *(path++);
1299                 if (c != ' ' && c != '.')
1300                         return 0;
1301         }
1302         return 1;
1303 }
1304
1305 int is_ntfs_dotgit(const char *name)
1306 {
1307         int len;
1308
1309         for (len = 0; ; len++)
1310                 if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
1311                         if (only_spaces_and_periods(name, len, 4) &&
1312                                         !strncasecmp(name, ".git", 4))
1313                                 return 1;
1314                         if (only_spaces_and_periods(name, len, 5) &&
1315                                         !strncasecmp(name, "git~1", 5))
1316                                 return 1;
1317                         if (name[len] != '\\')
1318                                 return 0;
1319                         name += len + 1;
1320                         len = -1;
1321                 }
1322 }
1323
1324 int looks_like_command_line_option(const char *str)
1325 {
1326         return str && str[0] == '-';
1327 }
1328
1329 char *xdg_config_home(const char *filename)
1330 {
1331         const char *home, *config_home;
1332
1333         assert(filename);
1334         config_home = getenv("XDG_CONFIG_HOME");
1335         if (config_home && *config_home)
1336                 return mkpathdup("%s/git/%s", config_home, filename);
1337
1338         home = getenv("HOME");
1339         if (home)
1340                 return mkpathdup("%s/.config/git/%s", home, filename);
1341         return NULL;
1342 }
1343
1344 char *xdg_cache_home(const char *filename)
1345 {
1346         const char *home, *cache_home;
1347
1348         assert(filename);
1349         cache_home = getenv("XDG_CACHE_HOME");
1350         if (cache_home && *cache_home)
1351                 return mkpathdup("%s/git/%s", cache_home, filename);
1352
1353         home = getenv("HOME");
1354         if (home)
1355                 return mkpathdup("%s/.cache/git/%s", home, filename);
1356         return NULL;
1357 }
1358
1359 GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
1360 GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
1361 GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
1362 GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
1363 GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
1364 GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
1365 GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
1366 GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
1367 GIT_PATH_FUNC(git_path_shallow, "shallow")