9be6804a976a4992caaac6eb4ebc514283260963
   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
  13static 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
  22static char bad_path[] = "/bad-path/";
  23
  24static 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
  36static 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
  47static 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
  54char *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
  69static 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 */
  77static 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
  87static 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
  99struct 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
 108static 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 */
 151struct trie {
 152        struct trie *children[256];
 153        int len;
 154        char *contents;
 155        void *value;
 156};
 157
 158static 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 */
 174static 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
 233typedef 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 */
 258static 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
 307static struct trie common_trie;
 308static int common_trie_done_setup;
 309
 310static 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 */
 327static 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
 343static 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
 352void 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
 374static void adjust_git_path(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                              get_graft_file(), strlen(get_graft_file()));
 380        else if (!strcmp(base, "index"))
 381                strbuf_splice(buf, 0, buf->len,
 382                              get_index_file(), strlen(get_index_file()));
 383        else if (dir_prefix(base, "objects"))
 384                replace_dir(buf, git_dir_len + 7, get_object_directory());
 385        else if (git_hooks_path && dir_prefix(base, "hooks"))
 386                replace_dir(buf, git_dir_len + 5, git_hooks_path);
 387        else if (the_repository->different_commondir)
 388                update_common_dir(buf, git_dir_len, get_git_common_dir());
 389}
 390
 391static void do_git_path(const struct worktree *wt, struct strbuf *buf,
 392                        const char *fmt, va_list args)
 393{
 394        int gitdir_len;
 395        strbuf_addstr(buf, get_worktree_git_dir(wt));
 396        if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 397                strbuf_addch(buf, '/');
 398        gitdir_len = buf->len;
 399        strbuf_vaddf(buf, fmt, args);
 400        adjust_git_path(buf, gitdir_len);
 401        strbuf_cleanup_path(buf);
 402}
 403
 404char *git_path_buf(struct strbuf *buf, const char *fmt, ...)
 405{
 406        va_list args;
 407        strbuf_reset(buf);
 408        va_start(args, fmt);
 409        do_git_path(NULL, buf, fmt, args);
 410        va_end(args);
 411        return buf->buf;
 412}
 413
 414void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 415{
 416        va_list args;
 417        va_start(args, fmt);
 418        do_git_path(NULL, sb, fmt, args);
 419        va_end(args);
 420}
 421
 422const char *git_path(const char *fmt, ...)
 423{
 424        struct strbuf *pathname = get_pathname();
 425        va_list args;
 426        va_start(args, fmt);
 427        do_git_path(NULL, pathname, fmt, args);
 428        va_end(args);
 429        return pathname->buf;
 430}
 431
 432char *git_pathdup(const char *fmt, ...)
 433{
 434        struct strbuf path = STRBUF_INIT;
 435        va_list args;
 436        va_start(args, fmt);
 437        do_git_path(NULL, &path, fmt, args);
 438        va_end(args);
 439        return strbuf_detach(&path, NULL);
 440}
 441
 442char *mkpathdup(const char *fmt, ...)
 443{
 444        struct strbuf sb = STRBUF_INIT;
 445        va_list args;
 446        va_start(args, fmt);
 447        strbuf_vaddf(&sb, fmt, args);
 448        va_end(args);
 449        strbuf_cleanup_path(&sb);
 450        return strbuf_detach(&sb, NULL);
 451}
 452
 453const char *mkpath(const char *fmt, ...)
 454{
 455        va_list args;
 456        struct strbuf *pathname = get_pathname();
 457        va_start(args, fmt);
 458        strbuf_vaddf(pathname, fmt, args);
 459        va_end(args);
 460        return cleanup_path(pathname->buf);
 461}
 462
 463const char *worktree_git_path(const struct worktree *wt, const char *fmt, ...)
 464{
 465        struct strbuf *pathname = get_pathname();
 466        va_list args;
 467        va_start(args, fmt);
 468        do_git_path(wt, pathname, fmt, args);
 469        va_end(args);
 470        return pathname->buf;
 471}
 472
 473/* Returns 0 on success, negative on failure. */
 474static int do_submodule_path(struct strbuf *buf, const char *path,
 475                             const char *fmt, va_list args)
 476{
 477        struct strbuf git_submodule_common_dir = STRBUF_INIT;
 478        struct strbuf git_submodule_dir = STRBUF_INIT;
 479        int ret;
 480
 481        ret = submodule_to_gitdir(&git_submodule_dir, path);
 482        if (ret)
 483                goto cleanup;
 484
 485        strbuf_complete(&git_submodule_dir, '/');
 486        strbuf_addbuf(buf, &git_submodule_dir);
 487        strbuf_vaddf(buf, fmt, args);
 488
 489        if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
 490                update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);
 491
 492        strbuf_cleanup_path(buf);
 493
 494cleanup:
 495        strbuf_release(&git_submodule_dir);
 496        strbuf_release(&git_submodule_common_dir);
 497        return ret;
 498}
 499
 500char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 501{
 502        int err;
 503        va_list args;
 504        struct strbuf buf = STRBUF_INIT;
 505        va_start(args, fmt);
 506        err = do_submodule_path(&buf, path, fmt, args);
 507        va_end(args);
 508        if (err) {
 509                strbuf_release(&buf);
 510                return NULL;
 511        }
 512        return strbuf_detach(&buf, NULL);
 513}
 514
 515int strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 516                              const char *fmt, ...)
 517{
 518        int err;
 519        va_list args;
 520        va_start(args, fmt);
 521        err = do_submodule_path(buf, path, fmt, args);
 522        va_end(args);
 523
 524        return err;
 525}
 526
 527static void do_git_common_path(const struct repository *repo,
 528                               struct strbuf *buf,
 529                               const char *fmt,
 530                               va_list args)
 531{
 532        strbuf_addstr(buf, repo->commondir);
 533        if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 534                strbuf_addch(buf, '/');
 535        strbuf_vaddf(buf, fmt, args);
 536        strbuf_cleanup_path(buf);
 537}
 538
 539const char *git_common_path(const char *fmt, ...)
 540{
 541        struct strbuf *pathname = get_pathname();
 542        va_list args;
 543        va_start(args, fmt);
 544        do_git_common_path(the_repository, pathname, fmt, args);
 545        va_end(args);
 546        return pathname->buf;
 547}
 548
 549void strbuf_git_common_path(struct strbuf *sb,
 550                            const struct repository *repo,
 551                            const char *fmt, ...)
 552{
 553        va_list args;
 554        va_start(args, fmt);
 555        do_git_common_path(repo, sb, fmt, args);
 556        va_end(args);
 557}
 558
 559int validate_headref(const char *path)
 560{
 561        struct stat st;
 562        char *buf, buffer[256];
 563        unsigned char sha1[20];
 564        int fd;
 565        ssize_t len;
 566
 567        if (lstat(path, &st) < 0)
 568                return -1;
 569
 570        /* Make sure it is a "refs/.." symlink */
 571        if (S_ISLNK(st.st_mode)) {
 572                len = readlink(path, buffer, sizeof(buffer)-1);
 573                if (len >= 5 && !memcmp("refs/", buffer, 5))
 574                        return 0;
 575                return -1;
 576        }
 577
 578        /*
 579         * Anything else, just open it and try to see if it is a symbolic ref.
 580         */
 581        fd = open(path, O_RDONLY);
 582        if (fd < 0)
 583                return -1;
 584        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 585        close(fd);
 586
 587        /*
 588         * Is it a symbolic ref?
 589         */
 590        if (len < 4)
 591                return -1;
 592        if (!memcmp("ref:", buffer, 4)) {
 593                buf = buffer + 4;
 594                len -= 4;
 595                while (len && isspace(*buf))
 596                        buf++, len--;
 597                if (len >= 5 && !memcmp("refs/", buf, 5))
 598                        return 0;
 599        }
 600
 601        /*
 602         * Is this a detached HEAD?
 603         */
 604        if (!get_sha1_hex(buffer, sha1))
 605                return 0;
 606
 607        return -1;
 608}
 609
 610static struct passwd *getpw_str(const char *username, size_t len)
 611{
 612        struct passwd *pw;
 613        char *username_z = xmemdupz(username, len);
 614        pw = getpwnam(username_z);
 615        free(username_z);
 616        return pw;
 617}
 618
 619/*
 620 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 621 * then it is a newly allocated string. Returns NULL on getpw failure or
 622 * if path is NULL.
 623 *
 624 * If real_home is true, real_path($HOME) is used in the expansion.
 625 */
 626char *expand_user_path(const char *path, int real_home)
 627{
 628        struct strbuf user_path = STRBUF_INIT;
 629        const char *to_copy = path;
 630
 631        if (path == NULL)
 632                goto return_null;
 633        if (path[0] == '~') {
 634                const char *first_slash = strchrnul(path, '/');
 635                const char *username = path + 1;
 636                size_t username_len = first_slash - username;
 637                if (username_len == 0) {
 638                        const char *home = getenv("HOME");
 639                        if (!home)
 640                                goto return_null;
 641                        if (real_home)
 642                                strbuf_addstr(&user_path, real_path(home));
 643                        else
 644                                strbuf_addstr(&user_path, home);
 645#ifdef GIT_WINDOWS_NATIVE
 646                        convert_slashes(user_path.buf);
 647#endif
 648                } else {
 649                        struct passwd *pw = getpw_str(username, username_len);
 650                        if (!pw)
 651                                goto return_null;
 652                        strbuf_addstr(&user_path, pw->pw_dir);
 653                }
 654                to_copy = first_slash;
 655        }
 656        strbuf_addstr(&user_path, to_copy);
 657        return strbuf_detach(&user_path, NULL);
 658return_null:
 659        strbuf_release(&user_path);
 660        return NULL;
 661}
 662
 663/*
 664 * First, one directory to try is determined by the following algorithm.
 665 *
 666 * (0) If "strict" is given, the path is used as given and no DWIM is
 667 *     done. Otherwise:
 668 * (1) "~/path" to mean path under the running user's home directory;
 669 * (2) "~user/path" to mean path under named user's home directory;
 670 * (3) "relative/path" to mean cwd relative directory; or
 671 * (4) "/absolute/path" to mean absolute directory.
 672 *
 673 * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 674 * in this order. We select the first one that is a valid git repository, and
 675 * chdir() to it. If none match, or we fail to chdir, we return NULL.
 676 *
 677 * If all goes well, we return the directory we used to chdir() (but
 678 * before ~user is expanded), avoiding getcwd() resolving symbolic
 679 * links.  User relative paths are also returned as they are given,
 680 * except DWIM suffixing.
 681 */
 682const char *enter_repo(const char *path, int strict)
 683{
 684        static struct strbuf validated_path = STRBUF_INIT;
 685        static struct strbuf used_path = STRBUF_INIT;
 686
 687        if (!path)
 688                return NULL;
 689
 690        if (!strict) {
 691                static const char *suffix[] = {
 692                        "/.git", "", ".git/.git", ".git", NULL,
 693                };
 694                const char *gitfile;
 695                int len = strlen(path);
 696                int i;
 697                while ((1 < len) && (path[len-1] == '/'))
 698                        len--;
 699
 700                /*
 701                 * We can handle arbitrary-sized buffers, but this remains as a
 702                 * sanity check on untrusted input.
 703                 */
 704                if (PATH_MAX <= len)
 705                        return NULL;
 706
 707                strbuf_reset(&used_path);
 708                strbuf_reset(&validated_path);
 709                strbuf_add(&used_path, path, len);
 710                strbuf_add(&validated_path, path, len);
 711
 712                if (used_path.buf[0] == '~') {
 713                        char *newpath = expand_user_path(used_path.buf, 0);
 714                        if (!newpath)
 715                                return NULL;
 716                        strbuf_attach(&used_path, newpath, strlen(newpath),
 717                                      strlen(newpath));
 718                }
 719                for (i = 0; suffix[i]; i++) {
 720                        struct stat st;
 721                        size_t baselen = used_path.len;
 722                        strbuf_addstr(&used_path, suffix[i]);
 723                        if (!stat(used_path.buf, &st) &&
 724                            (S_ISREG(st.st_mode) ||
 725                            (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
 726                                strbuf_addstr(&validated_path, suffix[i]);
 727                                break;
 728                        }
 729                        strbuf_setlen(&used_path, baselen);
 730                }
 731                if (!suffix[i])
 732                        return NULL;
 733                gitfile = read_gitfile(used_path.buf);
 734                if (gitfile) {
 735                        strbuf_reset(&used_path);
 736                        strbuf_addstr(&used_path, gitfile);
 737                }
 738                if (chdir(used_path.buf))
 739                        return NULL;
 740                path = validated_path.buf;
 741        }
 742        else {
 743                const char *gitfile = read_gitfile(path);
 744                if (gitfile)
 745                        path = gitfile;
 746                if (chdir(path))
 747                        return NULL;
 748        }
 749
 750        if (is_git_directory(".")) {
 751                set_git_dir(".");
 752                check_repository_format();
 753                return path;
 754        }
 755
 756        return NULL;
 757}
 758
 759static int calc_shared_perm(int mode)
 760{
 761        int tweak;
 762
 763        if (get_shared_repository() < 0)
 764                tweak = -get_shared_repository();
 765        else
 766                tweak = get_shared_repository();
 767
 768        if (!(mode & S_IWUSR))
 769                tweak &= ~0222;
 770        if (mode & S_IXUSR)
 771                /* Copy read bits to execute bits */
 772                tweak |= (tweak & 0444) >> 2;
 773        if (get_shared_repository() < 0)
 774                mode = (mode & ~0777) | tweak;
 775        else
 776                mode |= tweak;
 777
 778        return mode;
 779}
 780
 781
 782int adjust_shared_perm(const char *path)
 783{
 784        int old_mode, new_mode;
 785
 786        if (!get_shared_repository())
 787                return 0;
 788        if (get_st_mode_bits(path, &old_mode) < 0)
 789                return -1;
 790
 791        new_mode = calc_shared_perm(old_mode);
 792        if (S_ISDIR(old_mode)) {
 793                /* Copy read bits to execute bits */
 794                new_mode |= (new_mode & 0444) >> 2;
 795                new_mode |= FORCE_DIR_SET_GID;
 796        }
 797
 798        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 799                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 800                return -2;
 801        return 0;
 802}
 803
 804void safe_create_dir(const char *dir, int share)
 805{
 806        if (mkdir(dir, 0777) < 0) {
 807                if (errno != EEXIST) {
 808                        perror(dir);
 809                        exit(1);
 810                }
 811        }
 812        else if (share && adjust_shared_perm(dir))
 813                die(_("Could not make %s writable by group"), dir);
 814}
 815
 816static int have_same_root(const char *path1, const char *path2)
 817{
 818        int is_abs1, is_abs2;
 819
 820        is_abs1 = is_absolute_path(path1);
 821        is_abs2 = is_absolute_path(path2);
 822        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 823               (!is_abs1 && !is_abs2);
 824}
 825
 826/*
 827 * Give path as relative to prefix.
 828 *
 829 * The strbuf may or may not be used, so do not assume it contains the
 830 * returned path.
 831 */
 832const char *relative_path(const char *in, const char *prefix,
 833                          struct strbuf *sb)
 834{
 835        int in_len = in ? strlen(in) : 0;
 836        int prefix_len = prefix ? strlen(prefix) : 0;
 837        int in_off = 0;
 838        int prefix_off = 0;
 839        int i = 0, j = 0;
 840
 841        if (!in_len)
 842                return "./";
 843        else if (!prefix_len)
 844                return in;
 845
 846        if (have_same_root(in, prefix))
 847                /* bypass dos_drive, for "c:" is identical to "C:" */
 848                i = j = has_dos_drive_prefix(in);
 849        else {
 850                return in;
 851        }
 852
 853        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 854                if (is_dir_sep(prefix[i])) {
 855                        while (is_dir_sep(prefix[i]))
 856                                i++;
 857                        while (is_dir_sep(in[j]))
 858                                j++;
 859                        prefix_off = i;
 860                        in_off = j;
 861                } else {
 862                        i++;
 863                        j++;
 864                }
 865        }
 866
 867        if (
 868            /* "prefix" seems like prefix of "in" */
 869            i >= prefix_len &&
 870            /*
 871             * but "/foo" is not a prefix of "/foobar"
 872             * (i.e. prefix not end with '/')
 873             */
 874            prefix_off < prefix_len) {
 875                if (j >= in_len) {
 876                        /* in="/a/b", prefix="/a/b" */
 877                        in_off = in_len;
 878                } else if (is_dir_sep(in[j])) {
 879                        /* in="/a/b/c", prefix="/a/b" */
 880                        while (is_dir_sep(in[j]))
 881                                j++;
 882                        in_off = j;
 883                } else {
 884                        /* in="/a/bbb/c", prefix="/a/b" */
 885                        i = prefix_off;
 886                }
 887        } else if (
 888                   /* "in" is short than "prefix" */
 889                   j >= in_len &&
 890                   /* "in" not end with '/' */
 891                   in_off < in_len) {
 892                if (is_dir_sep(prefix[i])) {
 893                        /* in="/a/b", prefix="/a/b/c/" */
 894                        while (is_dir_sep(prefix[i]))
 895                                i++;
 896                        in_off = in_len;
 897                }
 898        }
 899        in += in_off;
 900        in_len -= in_off;
 901
 902        if (i >= prefix_len) {
 903                if (!in_len)
 904                        return "./";
 905                else
 906                        return in;
 907        }
 908
 909        strbuf_reset(sb);
 910        strbuf_grow(sb, in_len);
 911
 912        while (i < prefix_len) {
 913                if (is_dir_sep(prefix[i])) {
 914                        strbuf_addstr(sb, "../");
 915                        while (is_dir_sep(prefix[i]))
 916                                i++;
 917                        continue;
 918                }
 919                i++;
 920        }
 921        if (!is_dir_sep(prefix[prefix_len - 1]))
 922                strbuf_addstr(sb, "../");
 923
 924        strbuf_addstr(sb, in);
 925
 926        return sb->buf;
 927}
 928
 929/*
 930 * A simpler implementation of relative_path
 931 *
 932 * Get relative path by removing "prefix" from "in". This function
 933 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 934 * to increase performance when traversing the path to work_tree.
 935 */
 936const char *remove_leading_path(const char *in, const char *prefix)
 937{
 938        static struct strbuf buf = STRBUF_INIT;
 939        int i = 0, j = 0;
 940
 941        if (!prefix || !prefix[0])
 942                return in;
 943        while (prefix[i]) {
 944                if (is_dir_sep(prefix[i])) {
 945                        if (!is_dir_sep(in[j]))
 946                                return in;
 947                        while (is_dir_sep(prefix[i]))
 948                                i++;
 949                        while (is_dir_sep(in[j]))
 950                                j++;
 951                        continue;
 952                } else if (in[j] != prefix[i]) {
 953                        return in;
 954                }
 955                i++;
 956                j++;
 957        }
 958        if (
 959            /* "/foo" is a prefix of "/foo" */
 960            in[j] &&
 961            /* "/foo" is not a prefix of "/foobar" */
 962            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 963           )
 964                return in;
 965        while (is_dir_sep(in[j]))
 966                j++;
 967
 968        strbuf_reset(&buf);
 969        if (!in[j])
 970                strbuf_addstr(&buf, ".");
 971        else
 972                strbuf_addstr(&buf, in + j);
 973        return buf.buf;
 974}
 975
 976/*
 977 * It is okay if dst == src, but they should not overlap otherwise.
 978 *
 979 * Performs the following normalizations on src, storing the result in dst:
 980 * - Ensures that components are separated by '/' (Windows only)
 981 * - Squashes sequences of '/' except "//server/share" on Windows
 982 * - Removes "." components.
 983 * - Removes ".." components, and the components the precede them.
 984 * Returns failure (non-zero) if a ".." component appears as first path
 985 * component anytime during the normalization. Otherwise, returns success (0).
 986 *
 987 * Note that this function is purely textual.  It does not follow symlinks,
 988 * verify the existence of the path, or make any system calls.
 989 *
 990 * prefix_len != NULL is for a specific case of prefix_pathspec():
 991 * assume that src == dst and src[0..prefix_len-1] is already
 992 * normalized, any time "../" eats up to the prefix_len part,
 993 * prefix_len is reduced. In the end prefix_len is the remaining
 994 * prefix that has not been overridden by user pathspec.
 995 *
 996 * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
 997 * For everything but the root folder itself, the normalized path should not
 998 * end with a '/', then the callers need to be fixed up accordingly.
 999 *
1000 */
1001int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
1002{
1003        char *dst0;
1004        const char *end;
1005
1006        /*
1007         * Copy initial part of absolute path: "/", "C:/", "//server/share/".
1008         */
1009        end = src + offset_1st_component(src);
1010        while (src < end) {
1011                char c = *src++;
1012                if (is_dir_sep(c))
1013                        c = '/';
1014                *dst++ = c;
1015        }
1016        dst0 = dst;
1017
1018        while (is_dir_sep(*src))
1019                src++;
1020
1021        for (;;) {
1022                char c = *src;
1023
1024                /*
1025                 * A path component that begins with . could be
1026                 * special:
1027                 * (1) "." and ends   -- ignore and terminate.
1028                 * (2) "./"           -- ignore them, eat slash and continue.
1029                 * (3) ".." and ends  -- strip one and terminate.
1030                 * (4) "../"          -- strip one, eat slash and continue.
1031                 */
1032                if (c == '.') {
1033                        if (!src[1]) {
1034                                /* (1) */
1035                                src++;
1036                        } else if (is_dir_sep(src[1])) {
1037                                /* (2) */
1038                                src += 2;
1039                                while (is_dir_sep(*src))
1040                                        src++;
1041                                continue;
1042                        } else if (src[1] == '.') {
1043                                if (!src[2]) {
1044                                        /* (3) */
1045                                        src += 2;
1046                                        goto up_one;
1047                                } else if (is_dir_sep(src[2])) {
1048                                        /* (4) */
1049                                        src += 3;
1050                                        while (is_dir_sep(*src))
1051                                                src++;
1052                                        goto up_one;
1053                                }
1054                        }
1055                }
1056
1057                /* copy up to the next '/', and eat all '/' */
1058                while ((c = *src++) != '\0' && !is_dir_sep(c))
1059                        *dst++ = c;
1060                if (is_dir_sep(c)) {
1061                        *dst++ = '/';
1062                        while (is_dir_sep(c))
1063                                c = *src++;
1064                        src--;
1065                } else if (!c)
1066                        break;
1067                continue;
1068
1069        up_one:
1070                /*
1071                 * dst0..dst is prefix portion, and dst[-1] is '/';
1072                 * go up one level.
1073                 */
1074                dst--;  /* go to trailing '/' */
1075                if (dst <= dst0)
1076                        return -1;
1077                /* Windows: dst[-1] cannot be backslash anymore */
1078                while (dst0 < dst && dst[-1] != '/')
1079                        dst--;
1080                if (prefix_len && *prefix_len > dst - dst0)
1081                        *prefix_len = dst - dst0;
1082        }
1083        *dst = '\0';
1084        return 0;
1085}
1086
1087int normalize_path_copy(char *dst, const char *src)
1088{
1089        return normalize_path_copy_len(dst, src, NULL);
1090}
1091
1092/*
1093 * path = Canonical absolute path
1094 * prefixes = string_list containing normalized, absolute paths without
1095 * trailing slashes (except for the root directory, which is denoted by "/").
1096 *
1097 * Determines, for each path in prefixes, whether the "prefix"
1098 * is an ancestor directory of path.  Returns the length of the longest
1099 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
1100 * is an ancestor.  (Note that this means 0 is returned if prefixes is
1101 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
1102 * are not considered to be their own ancestors.  path must be in a
1103 * canonical form: empty components, or "." or ".." components are not
1104 * allowed.
1105 */
1106int longest_ancestor_length(const char *path, struct string_list *prefixes)
1107{
1108        int i, max_len = -1;
1109
1110        if (!strcmp(path, "/"))
1111                return -1;
1112
1113        for (i = 0; i < prefixes->nr; i++) {
1114                const char *ceil = prefixes->items[i].string;
1115                int len = strlen(ceil);
1116
1117                if (len == 1 && ceil[0] == '/')
1118                        len = 0; /* root matches anything, with length 0 */
1119                else if (!strncmp(path, ceil, len) && path[len] == '/')
1120                        ; /* match of length len */
1121                else
1122                        continue; /* no match */
1123
1124                if (len > max_len)
1125                        max_len = len;
1126        }
1127
1128        return max_len;
1129}
1130
1131/* strip arbitrary amount of directory separators at end of path */
1132static inline int chomp_trailing_dir_sep(const char *path, int len)
1133{
1134        while (len && is_dir_sep(path[len - 1]))
1135                len--;
1136        return len;
1137}
1138
1139/*
1140 * If path ends with suffix (complete path components), returns the
1141 * part before suffix (sans trailing directory separators).
1142 * Otherwise returns NULL.
1143 */
1144char *strip_path_suffix(const char *path, const char *suffix)
1145{
1146        int path_len = strlen(path), suffix_len = strlen(suffix);
1147
1148        while (suffix_len) {
1149                if (!path_len)
1150                        return NULL;
1151
1152                if (is_dir_sep(path[path_len - 1])) {
1153                        if (!is_dir_sep(suffix[suffix_len - 1]))
1154                                return NULL;
1155                        path_len = chomp_trailing_dir_sep(path, path_len);
1156                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
1157                }
1158                else if (path[--path_len] != suffix[--suffix_len])
1159                        return NULL;
1160        }
1161
1162        if (path_len && !is_dir_sep(path[path_len - 1]))
1163                return NULL;
1164        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
1165}
1166
1167int daemon_avoid_alias(const char *p)
1168{
1169        int sl, ndot;
1170
1171        /*
1172         * This resurrects the belts and suspenders paranoia check by HPA
1173         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
1174         * does not do getcwd() based path canonicalization.
1175         *
1176         * sl becomes true immediately after seeing '/' and continues to
1177         * be true as long as dots continue after that without intervening
1178         * non-dot character.
1179         */
1180        if (!p || (*p != '/' && *p != '~'))
1181                return -1;
1182        sl = 1; ndot = 0;
1183        p++;
1184
1185        while (1) {
1186                char ch = *p++;
1187                if (sl) {
1188                        if (ch == '.')
1189                                ndot++;
1190                        else if (ch == '/') {
1191                                if (ndot < 3)
1192                                        /* reject //, /./ and /../ */
1193                                        return -1;
1194                                ndot = 0;
1195                        }
1196                        else if (ch == 0) {
1197                                if (0 < ndot && ndot < 3)
1198                                        /* reject /.$ and /..$ */
1199                                        return -1;
1200                                return 0;
1201                        }
1202                        else
1203                                sl = ndot = 0;
1204                }
1205                else if (ch == 0)
1206                        return 0;
1207                else if (ch == '/') {
1208                        sl = 1;
1209                        ndot = 0;
1210                }
1211        }
1212}
1213
1214static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
1215{
1216        if (len < skip)
1217                return 0;
1218        len -= skip;
1219        path += skip;
1220        while (len-- > 0) {
1221                char c = *(path++);
1222                if (c != ' ' && c != '.')
1223                        return 0;
1224        }
1225        return 1;
1226}
1227
1228int is_ntfs_dotgit(const char *name)
1229{
1230        int len;
1231
1232        for (len = 0; ; len++)
1233                if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
1234                        if (only_spaces_and_periods(name, len, 4) &&
1235                                        !strncasecmp(name, ".git", 4))
1236                                return 1;
1237                        if (only_spaces_and_periods(name, len, 5) &&
1238                                        !strncasecmp(name, "git~1", 5))
1239                                return 1;
1240                        if (name[len] != '\\')
1241                                return 0;
1242                        name += len + 1;
1243                        len = -1;
1244                }
1245}
1246
1247char *xdg_config_home(const char *filename)
1248{
1249        const char *home, *config_home;
1250
1251        assert(filename);
1252        config_home = getenv("XDG_CONFIG_HOME");
1253        if (config_home && *config_home)
1254                return mkpathdup("%s/git/%s", config_home, filename);
1255
1256        home = getenv("HOME");
1257        if (home)
1258                return mkpathdup("%s/.config/git/%s", home, filename);
1259        return NULL;
1260}
1261
1262char *xdg_cache_home(const char *filename)
1263{
1264        const char *home, *cache_home;
1265
1266        assert(filename);
1267        cache_home = getenv("XDG_CACHE_HOME");
1268        if (cache_home && *cache_home)
1269                return mkpathdup("%s/git/%s", cache_home, filename);
1270
1271        home = getenv("HOME");
1272        if (home)
1273                return mkpathdup("%s/.cache/git/%s", home, filename);
1274        return NULL;
1275}
1276
1277GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
1278GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
1279GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
1280GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
1281GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
1282GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
1283GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
1284GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
1285GIT_PATH_FUNC(git_path_shallow, "shallow")