path.con commit Merge branch 'rg/doc-pull-typofix' (741eaf7)
   1/*
   2 * Utilities for paths and pathnames
   3 */
   4#include "cache.h"
   5#include "strbuf.h"
   6#include "string-list.h"
   7#include "dir.h"
   8#include "worktree.h"
   9#include "submodule-config.h"
  10
  11static int get_st_mode_bits(const char *path, int *mode)
  12{
  13        struct stat st;
  14        if (lstat(path, &st) < 0)
  15                return -1;
  16        *mode = st.st_mode;
  17        return 0;
  18}
  19
  20static char bad_path[] = "/bad-path/";
  21
  22static struct strbuf *get_pathname(void)
  23{
  24        static struct strbuf pathname_array[4] = {
  25                STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
  26        };
  27        static int index;
  28        struct strbuf *sb = &pathname_array[index];
  29        index = (index + 1) % ARRAY_SIZE(pathname_array);
  30        strbuf_reset(sb);
  31        return sb;
  32}
  33
  34static char *cleanup_path(char *path)
  35{
  36        /* Clean it up */
  37        if (!memcmp(path, "./", 2)) {
  38                path += 2;
  39                while (*path == '/')
  40                        path++;
  41        }
  42        return path;
  43}
  44
  45static void strbuf_cleanup_path(struct strbuf *sb)
  46{
  47        char *path = cleanup_path(sb->buf);
  48        if (path > sb->buf)
  49                strbuf_remove(sb, 0, path - sb->buf);
  50}
  51
  52char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  53{
  54        va_list args;
  55        unsigned len;
  56
  57        va_start(args, fmt);
  58        len = vsnprintf(buf, n, fmt, args);
  59        va_end(args);
  60        if (len >= n) {
  61                strlcpy(buf, bad_path, n);
  62                return buf;
  63        }
  64        return cleanup_path(buf);
  65}
  66
  67static int dir_prefix(const char *buf, const char *dir)
  68{
  69        int len = strlen(dir);
  70        return !strncmp(buf, dir, len) &&
  71                (is_dir_sep(buf[len]) || buf[len] == '\0');
  72}
  73
  74/* $buf =~ m|$dir/+$file| but without regex */
  75static int is_dir_file(const char *buf, const char *dir, const char *file)
  76{
  77        int len = strlen(dir);
  78        if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
  79                return 0;
  80        while (is_dir_sep(buf[len]))
  81                len++;
  82        return !strcmp(buf + len, file);
  83}
  84
  85static void replace_dir(struct strbuf *buf, int len, const char *newdir)
  86{
  87        int newlen = strlen(newdir);
  88        int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
  89                !is_dir_sep(newdir[newlen - 1]);
  90        if (need_sep)
  91                len--;   /* keep one char, to be replaced with '/'  */
  92        strbuf_splice(buf, 0, len, newdir, newlen);
  93        if (need_sep)
  94                buf->buf[newlen] = '/';
  95}
  96
  97struct common_dir {
  98        /* Not considered garbage for report_linked_checkout_garbage */
  99        unsigned ignore_garbage:1;
 100        unsigned is_dir:1;
 101        /* Not common even though its parent is */
 102        unsigned exclude:1;
 103        const char *dirname;
 104};
 105
 106static struct common_dir common_list[] = {
 107        { 0, 1, 0, "branches" },
 108        { 0, 1, 0, "hooks" },
 109        { 0, 1, 0, "info" },
 110        { 0, 0, 1, "info/sparse-checkout" },
 111        { 1, 1, 0, "logs" },
 112        { 1, 1, 1, "logs/HEAD" },
 113        { 0, 1, 1, "logs/refs/bisect" },
 114        { 0, 1, 0, "lost-found" },
 115        { 0, 1, 0, "objects" },
 116        { 0, 1, 0, "refs" },
 117        { 0, 1, 1, "refs/bisect" },
 118        { 0, 1, 0, "remotes" },
 119        { 0, 1, 0, "worktrees" },
 120        { 0, 1, 0, "rr-cache" },
 121        { 0, 1, 0, "svn" },
 122        { 0, 0, 0, "config" },
 123        { 1, 0, 0, "gc.pid" },
 124        { 0, 0, 0, "packed-refs" },
 125        { 0, 0, 0, "shallow" },
 126        { 0, 0, 0, NULL }
 127};
 128
 129/*
 130 * A compressed trie.  A trie node consists of zero or more characters that
 131 * are common to all elements with this prefix, optionally followed by some
 132 * children.  If value is not NULL, the trie node is a terminal node.
 133 *
 134 * For example, consider the following set of strings:
 135 * abc
 136 * def
 137 * definite
 138 * definition
 139 *
 140 * The trie would look like:
 141 * root: len = 0, children a and d non-NULL, value = NULL.
 142 *    a: len = 2, contents = bc, value = (data for "abc")
 143 *    d: len = 2, contents = ef, children i non-NULL, value = (data for "def")
 144 *       i: len = 3, contents = nit, children e and i non-NULL, value = NULL
 145 *           e: len = 0, children all NULL, value = (data for "definite")
 146 *           i: len = 2, contents = on, children all NULL,
 147 *              value = (data for "definition")
 148 */
 149struct trie {
 150        struct trie *children[256];
 151        int len;
 152        char *contents;
 153        void *value;
 154};
 155
 156static struct trie *make_trie_node(const char *key, void *value)
 157{
 158        struct trie *new_node = xcalloc(1, sizeof(*new_node));
 159        new_node->len = strlen(key);
 160        if (new_node->len) {
 161                new_node->contents = xmalloc(new_node->len);
 162                memcpy(new_node->contents, key, new_node->len);
 163        }
 164        new_node->value = value;
 165        return new_node;
 166}
 167
 168/*
 169 * Add a key/value pair to a trie.  The key is assumed to be \0-terminated.
 170 * If there was an existing value for this key, return it.
 171 */
 172static void *add_to_trie(struct trie *root, const char *key, void *value)
 173{
 174        struct trie *child;
 175        void *old;
 176        int i;
 177
 178        if (!*key) {
 179                /* we have reached the end of the key */
 180                old = root->value;
 181                root->value = value;
 182                return old;
 183        }
 184
 185        for (i = 0; i < root->len; i++) {
 186                if (root->contents[i] == key[i])
 187                        continue;
 188
 189                /*
 190                 * Split this node: child will contain this node's
 191                 * existing children.
 192                 */
 193                child = malloc(sizeof(*child));
 194                memcpy(child->children, root->children, sizeof(root->children));
 195
 196                child->len = root->len - i - 1;
 197                if (child->len) {
 198                        child->contents = xstrndup(root->contents + i + 1,
 199                                                   child->len);
 200                }
 201                child->value = root->value;
 202                root->value = NULL;
 203                root->len = i;
 204
 205                memset(root->children, 0, sizeof(root->children));
 206                root->children[(unsigned char)root->contents[i]] = child;
 207
 208                /* This is the newly-added child. */
 209                root->children[(unsigned char)key[i]] =
 210                        make_trie_node(key + i + 1, value);
 211                return NULL;
 212        }
 213
 214        /* We have matched the entire compressed section */
 215        if (key[i]) {
 216                child = root->children[(unsigned char)key[root->len]];
 217                if (child) {
 218                        return add_to_trie(child, key + root->len + 1, value);
 219                } else {
 220                        child = make_trie_node(key + root->len + 1, value);
 221                        root->children[(unsigned char)key[root->len]] = child;
 222                        return NULL;
 223                }
 224        }
 225
 226        old = root->value;
 227        root->value = value;
 228        return old;
 229}
 230
 231typedef int (*match_fn)(const char *unmatched, void *data, void *baton);
 232
 233/*
 234 * Search a trie for some key.  Find the longest /-or-\0-terminated
 235 * prefix of the key for which the trie contains a value.  Call fn
 236 * with the unmatched portion of the key and the found value, and
 237 * return its return value.  If there is no such prefix, return -1.
 238 *
 239 * The key is partially normalized: consecutive slashes are skipped.
 240 *
 241 * For example, consider the trie containing only [refs,
 242 * refs/worktree] (both with values).
 243 *
 244 * | key             | unmatched  | val from node | return value |
 245 * |-----------------|------------|---------------|--------------|
 246 * | a               | not called | n/a           | -1           |
 247 * | refs            | \0         | refs          | as per fn    |
 248 * | refs/           | /          | refs          | as per fn    |
 249 * | refs/w          | /w         | refs          | as per fn    |
 250 * | refs/worktree   | \0         | refs/worktree | as per fn    |
 251 * | refs/worktree/  | /          | refs/worktree | as per fn    |
 252 * | refs/worktree/a | /a         | refs/worktree | as per fn    |
 253 * |-----------------|------------|---------------|--------------|
 254 *
 255 */
 256static int trie_find(struct trie *root, const char *key, match_fn fn,
 257                     void *baton)
 258{
 259        int i;
 260        int result;
 261        struct trie *child;
 262
 263        if (!*key) {
 264                /* we have reached the end of the key */
 265                if (root->value && !root->len)
 266                        return fn(key, root->value, baton);
 267                else
 268                        return -1;
 269        }
 270
 271        for (i = 0; i < root->len; i++) {
 272                /* Partial path normalization: skip consecutive slashes. */
 273                if (key[i] == '/' && key[i+1] == '/') {
 274                        key++;
 275                        continue;
 276                }
 277                if (root->contents[i] != key[i])
 278                        return -1;
 279        }
 280
 281        /* Matched the entire compressed section */
 282        key += i;
 283        if (!*key)
 284                /* End of key */
 285                return fn(key, root->value, baton);
 286
 287        /* Partial path normalization: skip consecutive slashes */
 288        while (key[0] == '/' && key[1] == '/')
 289                key++;
 290
 291        child = root->children[(unsigned char)*key];
 292        if (child)
 293                result = trie_find(child, key + 1, fn, baton);
 294        else
 295                result = -1;
 296
 297        if (result >= 0 || (*key != '/' && *key != 0))
 298                return result;
 299        if (root->value)
 300                return fn(key, root->value, baton);
 301        else
 302                return -1;
 303}
 304
 305static struct trie common_trie;
 306static int common_trie_done_setup;
 307
 308static void init_common_trie(void)
 309{
 310        struct common_dir *p;
 311
 312        if (common_trie_done_setup)
 313                return;
 314
 315        for (p = common_list; p->dirname; p++)
 316                add_to_trie(&common_trie, p->dirname, p);
 317
 318        common_trie_done_setup = 1;
 319}
 320
 321/*
 322 * Helper function for update_common_dir: returns 1 if the dir
 323 * prefix is common.
 324 */
 325static int check_common(const char *unmatched, void *value, void *baton)
 326{
 327        struct common_dir *dir = value;
 328
 329        if (!dir)
 330                return 0;
 331
 332        if (dir->is_dir && (unmatched[0] == 0 || unmatched[0] == '/'))
 333                return !dir->exclude;
 334
 335        if (!dir->is_dir && unmatched[0] == 0)
 336                return !dir->exclude;
 337
 338        return 0;
 339}
 340
 341static void update_common_dir(struct strbuf *buf, int git_dir_len,
 342                              const char *common_dir)
 343{
 344        char *base = buf->buf + git_dir_len;
 345        init_common_trie();
 346        if (!common_dir)
 347                common_dir = get_git_common_dir();
 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 (!git_common_dir_env)
 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 (git_graft_env && is_dir_file(base, "info", "grafts"))
 378                strbuf_splice(buf, 0, buf->len,
 379                              get_graft_file(), strlen(get_graft_file()));
 380        else if (git_index_env && !strcmp(base, "index"))
 381                strbuf_splice(buf, 0, buf->len,
 382                              get_index_file(), strlen(get_index_file()));
 383        else if (git_db_env && 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 (git_common_dir_env)
 388                update_common_dir(buf, git_dir_len, NULL);
 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(struct strbuf *buf,
 528                               const char *fmt,
 529                               va_list args)
 530{
 531        strbuf_addstr(buf, get_git_common_dir());
 532        if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 533                strbuf_addch(buf, '/');
 534        strbuf_vaddf(buf, fmt, args);
 535        strbuf_cleanup_path(buf);
 536}
 537
 538const char *git_common_path(const char *fmt, ...)
 539{
 540        struct strbuf *pathname = get_pathname();
 541        va_list args;
 542        va_start(args, fmt);
 543        do_git_common_path(pathname, fmt, args);
 544        va_end(args);
 545        return pathname->buf;
 546}
 547
 548void strbuf_git_common_path(struct strbuf *sb, const char *fmt, ...)
 549{
 550        va_list args;
 551        va_start(args, fmt);
 552        do_git_common_path(sb, fmt, args);
 553        va_end(args);
 554}
 555
 556int validate_headref(const char *path)
 557{
 558        struct stat st;
 559        char *buf, buffer[256];
 560        unsigned char sha1[20];
 561        int fd;
 562        ssize_t len;
 563
 564        if (lstat(path, &st) < 0)
 565                return -1;
 566
 567        /* Make sure it is a "refs/.." symlink */
 568        if (S_ISLNK(st.st_mode)) {
 569                len = readlink(path, buffer, sizeof(buffer)-1);
 570                if (len >= 5 && !memcmp("refs/", buffer, 5))
 571                        return 0;
 572                return -1;
 573        }
 574
 575        /*
 576         * Anything else, just open it and try to see if it is a symbolic ref.
 577         */
 578        fd = open(path, O_RDONLY);
 579        if (fd < 0)
 580                return -1;
 581        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 582        close(fd);
 583
 584        /*
 585         * Is it a symbolic ref?
 586         */
 587        if (len < 4)
 588                return -1;
 589        if (!memcmp("ref:", buffer, 4)) {
 590                buf = buffer + 4;
 591                len -= 4;
 592                while (len && isspace(*buf))
 593                        buf++, len--;
 594                if (len >= 5 && !memcmp("refs/", buf, 5))
 595                        return 0;
 596        }
 597
 598        /*
 599         * Is this a detached HEAD?
 600         */
 601        if (!get_sha1_hex(buffer, sha1))
 602                return 0;
 603
 604        return -1;
 605}
 606
 607static struct passwd *getpw_str(const char *username, size_t len)
 608{
 609        struct passwd *pw;
 610        char *username_z = xmemdupz(username, len);
 611        pw = getpwnam(username_z);
 612        free(username_z);
 613        return pw;
 614}
 615
 616/*
 617 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 618 * then it is a newly allocated string. Returns NULL on getpw failure or
 619 * if path is NULL.
 620 *
 621 * If real_home is true, real_path($HOME) is used in the expansion.
 622 */
 623char *expand_user_path(const char *path, int real_home)
 624{
 625        struct strbuf user_path = STRBUF_INIT;
 626        const char *to_copy = path;
 627
 628        if (path == NULL)
 629                goto return_null;
 630        if (path[0] == '~') {
 631                const char *first_slash = strchrnul(path, '/');
 632                const char *username = path + 1;
 633                size_t username_len = first_slash - username;
 634                if (username_len == 0) {
 635                        const char *home = getenv("HOME");
 636                        if (!home)
 637                                goto return_null;
 638                        if (real_home)
 639                                strbuf_addstr(&user_path, real_path(home));
 640                        else
 641                                strbuf_addstr(&user_path, home);
 642#ifdef GIT_WINDOWS_NATIVE
 643                        convert_slashes(user_path.buf);
 644#endif
 645                } else {
 646                        struct passwd *pw = getpw_str(username, username_len);
 647                        if (!pw)
 648                                goto return_null;
 649                        strbuf_addstr(&user_path, pw->pw_dir);
 650                }
 651                to_copy = first_slash;
 652        }
 653        strbuf_addstr(&user_path, to_copy);
 654        return strbuf_detach(&user_path, NULL);
 655return_null:
 656        strbuf_release(&user_path);
 657        return NULL;
 658}
 659
 660/*
 661 * First, one directory to try is determined by the following algorithm.
 662 *
 663 * (0) If "strict" is given, the path is used as given and no DWIM is
 664 *     done. Otherwise:
 665 * (1) "~/path" to mean path under the running user's home directory;
 666 * (2) "~user/path" to mean path under named user's home directory;
 667 * (3) "relative/path" to mean cwd relative directory; or
 668 * (4) "/absolute/path" to mean absolute directory.
 669 *
 670 * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 671 * in this order. We select the first one that is a valid git repository, and
 672 * chdir() to it. If none match, or we fail to chdir, we return NULL.
 673 *
 674 * If all goes well, we return the directory we used to chdir() (but
 675 * before ~user is expanded), avoiding getcwd() resolving symbolic
 676 * links.  User relative paths are also returned as they are given,
 677 * except DWIM suffixing.
 678 */
 679const char *enter_repo(const char *path, int strict)
 680{
 681        static struct strbuf validated_path = STRBUF_INIT;
 682        static struct strbuf used_path = STRBUF_INIT;
 683
 684        if (!path)
 685                return NULL;
 686
 687        if (!strict) {
 688                static const char *suffix[] = {
 689                        "/.git", "", ".git/.git", ".git", NULL,
 690                };
 691                const char *gitfile;
 692                int len = strlen(path);
 693                int i;
 694                while ((1 < len) && (path[len-1] == '/'))
 695                        len--;
 696
 697                /*
 698                 * We can handle arbitrary-sized buffers, but this remains as a
 699                 * sanity check on untrusted input.
 700                 */
 701                if (PATH_MAX <= len)
 702                        return NULL;
 703
 704                strbuf_reset(&used_path);
 705                strbuf_reset(&validated_path);
 706                strbuf_add(&used_path, path, len);
 707                strbuf_add(&validated_path, path, len);
 708
 709                if (used_path.buf[0] == '~') {
 710                        char *newpath = expand_user_path(used_path.buf, 0);
 711                        if (!newpath)
 712                                return NULL;
 713                        strbuf_attach(&used_path, newpath, strlen(newpath),
 714                                      strlen(newpath));
 715                }
 716                for (i = 0; suffix[i]; i++) {
 717                        struct stat st;
 718                        size_t baselen = used_path.len;
 719                        strbuf_addstr(&used_path, suffix[i]);
 720                        if (!stat(used_path.buf, &st) &&
 721                            (S_ISREG(st.st_mode) ||
 722                            (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
 723                                strbuf_addstr(&validated_path, suffix[i]);
 724                                break;
 725                        }
 726                        strbuf_setlen(&used_path, baselen);
 727                }
 728                if (!suffix[i])
 729                        return NULL;
 730                gitfile = read_gitfile(used_path.buf);
 731                if (gitfile) {
 732                        strbuf_reset(&used_path);
 733                        strbuf_addstr(&used_path, gitfile);
 734                }
 735                if (chdir(used_path.buf))
 736                        return NULL;
 737                path = validated_path.buf;
 738        }
 739        else {
 740                const char *gitfile = read_gitfile(path);
 741                if (gitfile)
 742                        path = gitfile;
 743                if (chdir(path))
 744                        return NULL;
 745        }
 746
 747        if (is_git_directory(".")) {
 748                set_git_dir(".");
 749                check_repository_format();
 750                return path;
 751        }
 752
 753        return NULL;
 754}
 755
 756static int calc_shared_perm(int mode)
 757{
 758        int tweak;
 759
 760        if (get_shared_repository() < 0)
 761                tweak = -get_shared_repository();
 762        else
 763                tweak = get_shared_repository();
 764
 765        if (!(mode & S_IWUSR))
 766                tweak &= ~0222;
 767        if (mode & S_IXUSR)
 768                /* Copy read bits to execute bits */
 769                tweak |= (tweak & 0444) >> 2;
 770        if (get_shared_repository() < 0)
 771                mode = (mode & ~0777) | tweak;
 772        else
 773                mode |= tweak;
 774
 775        return mode;
 776}
 777
 778
 779int adjust_shared_perm(const char *path)
 780{
 781        int old_mode, new_mode;
 782
 783        if (!get_shared_repository())
 784                return 0;
 785        if (get_st_mode_bits(path, &old_mode) < 0)
 786                return -1;
 787
 788        new_mode = calc_shared_perm(old_mode);
 789        if (S_ISDIR(old_mode)) {
 790                /* Copy read bits to execute bits */
 791                new_mode |= (new_mode & 0444) >> 2;
 792                new_mode |= FORCE_DIR_SET_GID;
 793        }
 794
 795        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 796                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 797                return -2;
 798        return 0;
 799}
 800
 801void safe_create_dir(const char *dir, int share)
 802{
 803        if (mkdir(dir, 0777) < 0) {
 804                if (errno != EEXIST) {
 805                        perror(dir);
 806                        exit(1);
 807                }
 808        }
 809        else if (share && adjust_shared_perm(dir))
 810                die(_("Could not make %s writable by group"), dir);
 811}
 812
 813static int have_same_root(const char *path1, const char *path2)
 814{
 815        int is_abs1, is_abs2;
 816
 817        is_abs1 = is_absolute_path(path1);
 818        is_abs2 = is_absolute_path(path2);
 819        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 820               (!is_abs1 && !is_abs2);
 821}
 822
 823/*
 824 * Give path as relative to prefix.
 825 *
 826 * The strbuf may or may not be used, so do not assume it contains the
 827 * returned path.
 828 */
 829const char *relative_path(const char *in, const char *prefix,
 830                          struct strbuf *sb)
 831{
 832        int in_len = in ? strlen(in) : 0;
 833        int prefix_len = prefix ? strlen(prefix) : 0;
 834        int in_off = 0;
 835        int prefix_off = 0;
 836        int i = 0, j = 0;
 837
 838        if (!in_len)
 839                return "./";
 840        else if (!prefix_len)
 841                return in;
 842
 843        if (have_same_root(in, prefix))
 844                /* bypass dos_drive, for "c:" is identical to "C:" */
 845                i = j = has_dos_drive_prefix(in);
 846        else {
 847                return in;
 848        }
 849
 850        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 851                if (is_dir_sep(prefix[i])) {
 852                        while (is_dir_sep(prefix[i]))
 853                                i++;
 854                        while (is_dir_sep(in[j]))
 855                                j++;
 856                        prefix_off = i;
 857                        in_off = j;
 858                } else {
 859                        i++;
 860                        j++;
 861                }
 862        }
 863
 864        if (
 865            /* "prefix" seems like prefix of "in" */
 866            i >= prefix_len &&
 867            /*
 868             * but "/foo" is not a prefix of "/foobar"
 869             * (i.e. prefix not end with '/')
 870             */
 871            prefix_off < prefix_len) {
 872                if (j >= in_len) {
 873                        /* in="/a/b", prefix="/a/b" */
 874                        in_off = in_len;
 875                } else if (is_dir_sep(in[j])) {
 876                        /* in="/a/b/c", prefix="/a/b" */
 877                        while (is_dir_sep(in[j]))
 878                                j++;
 879                        in_off = j;
 880                } else {
 881                        /* in="/a/bbb/c", prefix="/a/b" */
 882                        i = prefix_off;
 883                }
 884        } else if (
 885                   /* "in" is short than "prefix" */
 886                   j >= in_len &&
 887                   /* "in" not end with '/' */
 888                   in_off < in_len) {
 889                if (is_dir_sep(prefix[i])) {
 890                        /* in="/a/b", prefix="/a/b/c/" */
 891                        while (is_dir_sep(prefix[i]))
 892                                i++;
 893                        in_off = in_len;
 894                }
 895        }
 896        in += in_off;
 897        in_len -= in_off;
 898
 899        if (i >= prefix_len) {
 900                if (!in_len)
 901                        return "./";
 902                else
 903                        return in;
 904        }
 905
 906        strbuf_reset(sb);
 907        strbuf_grow(sb, in_len);
 908
 909        while (i < prefix_len) {
 910                if (is_dir_sep(prefix[i])) {
 911                        strbuf_addstr(sb, "../");
 912                        while (is_dir_sep(prefix[i]))
 913                                i++;
 914                        continue;
 915                }
 916                i++;
 917        }
 918        if (!is_dir_sep(prefix[prefix_len - 1]))
 919                strbuf_addstr(sb, "../");
 920
 921        strbuf_addstr(sb, in);
 922
 923        return sb->buf;
 924}
 925
 926/*
 927 * A simpler implementation of relative_path
 928 *
 929 * Get relative path by removing "prefix" from "in". This function
 930 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 931 * to increase performance when traversing the path to work_tree.
 932 */
 933const char *remove_leading_path(const char *in, const char *prefix)
 934{
 935        static struct strbuf buf = STRBUF_INIT;
 936        int i = 0, j = 0;
 937
 938        if (!prefix || !prefix[0])
 939                return in;
 940        while (prefix[i]) {
 941                if (is_dir_sep(prefix[i])) {
 942                        if (!is_dir_sep(in[j]))
 943                                return in;
 944                        while (is_dir_sep(prefix[i]))
 945                                i++;
 946                        while (is_dir_sep(in[j]))
 947                                j++;
 948                        continue;
 949                } else if (in[j] != prefix[i]) {
 950                        return in;
 951                }
 952                i++;
 953                j++;
 954        }
 955        if (
 956            /* "/foo" is a prefix of "/foo" */
 957            in[j] &&
 958            /* "/foo" is not a prefix of "/foobar" */
 959            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 960           )
 961                return in;
 962        while (is_dir_sep(in[j]))
 963                j++;
 964
 965        strbuf_reset(&buf);
 966        if (!in[j])
 967                strbuf_addstr(&buf, ".");
 968        else
 969                strbuf_addstr(&buf, in + j);
 970        return buf.buf;
 971}
 972
 973/*
 974 * It is okay if dst == src, but they should not overlap otherwise.
 975 *
 976 * Performs the following normalizations on src, storing the result in dst:
 977 * - Ensures that components are separated by '/' (Windows only)
 978 * - Squashes sequences of '/' except "//server/share" on Windows
 979 * - Removes "." components.
 980 * - Removes ".." components, and the components the precede them.
 981 * Returns failure (non-zero) if a ".." component appears as first path
 982 * component anytime during the normalization. Otherwise, returns success (0).
 983 *
 984 * Note that this function is purely textual.  It does not follow symlinks,
 985 * verify the existence of the path, or make any system calls.
 986 *
 987 * prefix_len != NULL is for a specific case of prefix_pathspec():
 988 * assume that src == dst and src[0..prefix_len-1] is already
 989 * normalized, any time "../" eats up to the prefix_len part,
 990 * prefix_len is reduced. In the end prefix_len is the remaining
 991 * prefix that has not been overridden by user pathspec.
 992 *
 993 * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
 994 * For everything but the root folder itself, the normalized path should not
 995 * end with a '/', then the callers need to be fixed up accordingly.
 996 *
 997 */
 998int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 999{
1000        char *dst0;
1001        const char *end;
1002
1003        /*
1004         * Copy initial part of absolute path: "/", "C:/", "//server/share/".
1005         */
1006        end = src + offset_1st_component(src);
1007        while (src < end) {
1008                char c = *src++;
1009                if (is_dir_sep(c))
1010                        c = '/';
1011                *dst++ = c;
1012        }
1013        dst0 = dst;
1014
1015        while (is_dir_sep(*src))
1016                src++;
1017
1018        for (;;) {
1019                char c = *src;
1020
1021                /*
1022                 * A path component that begins with . could be
1023                 * special:
1024                 * (1) "." and ends   -- ignore and terminate.
1025                 * (2) "./"           -- ignore them, eat slash and continue.
1026                 * (3) ".." and ends  -- strip one and terminate.
1027                 * (4) "../"          -- strip one, eat slash and continue.
1028                 */
1029                if (c == '.') {
1030                        if (!src[1]) {
1031                                /* (1) */
1032                                src++;
1033                        } else if (is_dir_sep(src[1])) {
1034                                /* (2) */
1035                                src += 2;
1036                                while (is_dir_sep(*src))
1037                                        src++;
1038                                continue;
1039                        } else if (src[1] == '.') {
1040                                if (!src[2]) {
1041                                        /* (3) */
1042                                        src += 2;
1043                                        goto up_one;
1044                                } else if (is_dir_sep(src[2])) {
1045                                        /* (4) */
1046                                        src += 3;
1047                                        while (is_dir_sep(*src))
1048                                                src++;
1049                                        goto up_one;
1050                                }
1051                        }
1052                }
1053
1054                /* copy up to the next '/', and eat all '/' */
1055                while ((c = *src++) != '\0' && !is_dir_sep(c))
1056                        *dst++ = c;
1057                if (is_dir_sep(c)) {
1058                        *dst++ = '/';
1059                        while (is_dir_sep(c))
1060                                c = *src++;
1061                        src--;
1062                } else if (!c)
1063                        break;
1064                continue;
1065
1066        up_one:
1067                /*
1068                 * dst0..dst is prefix portion, and dst[-1] is '/';
1069                 * go up one level.
1070                 */
1071                dst--;  /* go to trailing '/' */
1072                if (dst <= dst0)
1073                        return -1;
1074                /* Windows: dst[-1] cannot be backslash anymore */
1075                while (dst0 < dst && dst[-1] != '/')
1076                        dst--;
1077                if (prefix_len && *prefix_len > dst - dst0)
1078                        *prefix_len = dst - dst0;
1079        }
1080        *dst = '\0';
1081        return 0;
1082}
1083
1084int normalize_path_copy(char *dst, const char *src)
1085{
1086        return normalize_path_copy_len(dst, src, NULL);
1087}
1088
1089/*
1090 * path = Canonical absolute path
1091 * prefixes = string_list containing normalized, absolute paths without
1092 * trailing slashes (except for the root directory, which is denoted by "/").
1093 *
1094 * Determines, for each path in prefixes, whether the "prefix"
1095 * is an ancestor directory of path.  Returns the length of the longest
1096 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
1097 * is an ancestor.  (Note that this means 0 is returned if prefixes is
1098 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
1099 * are not considered to be their own ancestors.  path must be in a
1100 * canonical form: empty components, or "." or ".." components are not
1101 * allowed.
1102 */
1103int longest_ancestor_length(const char *path, struct string_list *prefixes)
1104{
1105        int i, max_len = -1;
1106
1107        if (!strcmp(path, "/"))
1108                return -1;
1109
1110        for (i = 0; i < prefixes->nr; i++) {
1111                const char *ceil = prefixes->items[i].string;
1112                int len = strlen(ceil);
1113
1114                if (len == 1 && ceil[0] == '/')
1115                        len = 0; /* root matches anything, with length 0 */
1116                else if (!strncmp(path, ceil, len) && path[len] == '/')
1117                        ; /* match of length len */
1118                else
1119                        continue; /* no match */
1120
1121                if (len > max_len)
1122                        max_len = len;
1123        }
1124
1125        return max_len;
1126}
1127
1128/* strip arbitrary amount of directory separators at end of path */
1129static inline int chomp_trailing_dir_sep(const char *path, int len)
1130{
1131        while (len && is_dir_sep(path[len - 1]))
1132                len--;
1133        return len;
1134}
1135
1136/*
1137 * If path ends with suffix (complete path components), returns the
1138 * part before suffix (sans trailing directory separators).
1139 * Otherwise returns NULL.
1140 */
1141char *strip_path_suffix(const char *path, const char *suffix)
1142{
1143        int path_len = strlen(path), suffix_len = strlen(suffix);
1144
1145        while (suffix_len) {
1146                if (!path_len)
1147                        return NULL;
1148
1149                if (is_dir_sep(path[path_len - 1])) {
1150                        if (!is_dir_sep(suffix[suffix_len - 1]))
1151                                return NULL;
1152                        path_len = chomp_trailing_dir_sep(path, path_len);
1153                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
1154                }
1155                else if (path[--path_len] != suffix[--suffix_len])
1156                        return NULL;
1157        }
1158
1159        if (path_len && !is_dir_sep(path[path_len - 1]))
1160                return NULL;
1161        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
1162}
1163
1164int daemon_avoid_alias(const char *p)
1165{
1166        int sl, ndot;
1167
1168        /*
1169         * This resurrects the belts and suspenders paranoia check by HPA
1170         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
1171         * does not do getcwd() based path canonicalization.
1172         *
1173         * sl becomes true immediately after seeing '/' and continues to
1174         * be true as long as dots continue after that without intervening
1175         * non-dot character.
1176         */
1177        if (!p || (*p != '/' && *p != '~'))
1178                return -1;
1179        sl = 1; ndot = 0;
1180        p++;
1181
1182        while (1) {
1183                char ch = *p++;
1184                if (sl) {
1185                        if (ch == '.')
1186                                ndot++;
1187                        else if (ch == '/') {
1188                                if (ndot < 3)
1189                                        /* reject //, /./ and /../ */
1190                                        return -1;
1191                                ndot = 0;
1192                        }
1193                        else if (ch == 0) {
1194                                if (0 < ndot && ndot < 3)
1195                                        /* reject /.$ and /..$ */
1196                                        return -1;
1197                                return 0;
1198                        }
1199                        else
1200                                sl = ndot = 0;
1201                }
1202                else if (ch == 0)
1203                        return 0;
1204                else if (ch == '/') {
1205                        sl = 1;
1206                        ndot = 0;
1207                }
1208        }
1209}
1210
1211static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
1212{
1213        if (len < skip)
1214                return 0;
1215        len -= skip;
1216        path += skip;
1217        while (len-- > 0) {
1218                char c = *(path++);
1219                if (c != ' ' && c != '.')
1220                        return 0;
1221        }
1222        return 1;
1223}
1224
1225int is_ntfs_dotgit(const char *name)
1226{
1227        int len;
1228
1229        for (len = 0; ; len++)
1230                if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
1231                        if (only_spaces_and_periods(name, len, 4) &&
1232                                        !strncasecmp(name, ".git", 4))
1233                                return 1;
1234                        if (only_spaces_and_periods(name, len, 5) &&
1235                                        !strncasecmp(name, "git~1", 5))
1236                                return 1;
1237                        if (name[len] != '\\')
1238                                return 0;
1239                        name += len + 1;
1240                        len = -1;
1241                }
1242}
1243
1244char *xdg_config_home(const char *filename)
1245{
1246        const char *home, *config_home;
1247
1248        assert(filename);
1249        config_home = getenv("XDG_CONFIG_HOME");
1250        if (config_home && *config_home)
1251                return mkpathdup("%s/git/%s", config_home, filename);
1252
1253        home = getenv("HOME");
1254        if (home)
1255                return mkpathdup("%s/.config/git/%s", home, filename);
1256        return NULL;
1257}
1258
1259char *xdg_cache_home(const char *filename)
1260{
1261        const char *home, *cache_home;
1262
1263        assert(filename);
1264        cache_home = getenv("XDG_CACHE_HOME");
1265        if (cache_home && *cache_home)
1266                return mkpathdup("%s/git/%s", cache_home, filename);
1267
1268        home = getenv("HOME");
1269        if (home)
1270                return mkpathdup("%s/.cache/git/%s", home, filename);
1271        return NULL;
1272}
1273
1274GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
1275GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
1276GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
1277GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
1278GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
1279GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
1280GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
1281GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
1282GIT_PATH_FUNC(git_path_shallow, "shallow")