path.con commit Merge branch 'jh/memihash-opt' (0330344)
   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. */
 474#define SUBMODULE_PATH_ERR_NOT_CONFIGURED -1
 475static int do_submodule_path(struct strbuf *buf, const char *path,
 476                             const char *fmt, va_list args)
 477{
 478        const char *git_dir;
 479        struct strbuf git_submodule_common_dir = STRBUF_INIT;
 480        struct strbuf git_submodule_dir = STRBUF_INIT;
 481        const struct submodule *sub;
 482        int err = 0;
 483
 484        strbuf_addstr(buf, path);
 485        strbuf_complete(buf, '/');
 486        strbuf_addstr(buf, ".git");
 487
 488        git_dir = read_gitfile(buf->buf);
 489        if (git_dir) {
 490                strbuf_reset(buf);
 491                strbuf_addstr(buf, git_dir);
 492        }
 493        if (!is_git_directory(buf->buf)) {
 494                gitmodules_config();
 495                sub = submodule_from_path(null_sha1, path);
 496                if (!sub) {
 497                        err = SUBMODULE_PATH_ERR_NOT_CONFIGURED;
 498                        goto cleanup;
 499                }
 500                strbuf_reset(buf);
 501                strbuf_git_path(buf, "%s/%s", "modules", sub->name);
 502        }
 503
 504        strbuf_addch(buf, '/');
 505        strbuf_addbuf(&git_submodule_dir, buf);
 506
 507        strbuf_vaddf(buf, fmt, args);
 508
 509        if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
 510                update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);
 511
 512        strbuf_cleanup_path(buf);
 513
 514cleanup:
 515        strbuf_release(&git_submodule_dir);
 516        strbuf_release(&git_submodule_common_dir);
 517
 518        return err;
 519}
 520
 521char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 522{
 523        int err;
 524        va_list args;
 525        struct strbuf buf = STRBUF_INIT;
 526        va_start(args, fmt);
 527        err = do_submodule_path(&buf, path, fmt, args);
 528        va_end(args);
 529        if (err) {
 530                strbuf_release(&buf);
 531                return NULL;
 532        }
 533        return strbuf_detach(&buf, NULL);
 534}
 535
 536int strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 537                              const char *fmt, ...)
 538{
 539        int err;
 540        va_list args;
 541        va_start(args, fmt);
 542        err = do_submodule_path(buf, path, fmt, args);
 543        va_end(args);
 544
 545        return err;
 546}
 547
 548static void do_git_common_path(struct strbuf *buf,
 549                               const char *fmt,
 550                               va_list args)
 551{
 552        strbuf_addstr(buf, get_git_common_dir());
 553        if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 554                strbuf_addch(buf, '/');
 555        strbuf_vaddf(buf, fmt, args);
 556        strbuf_cleanup_path(buf);
 557}
 558
 559const char *git_common_path(const char *fmt, ...)
 560{
 561        struct strbuf *pathname = get_pathname();
 562        va_list args;
 563        va_start(args, fmt);
 564        do_git_common_path(pathname, fmt, args);
 565        va_end(args);
 566        return pathname->buf;
 567}
 568
 569void strbuf_git_common_path(struct strbuf *sb, const char *fmt, ...)
 570{
 571        va_list args;
 572        va_start(args, fmt);
 573        do_git_common_path(sb, fmt, args);
 574        va_end(args);
 575}
 576
 577int validate_headref(const char *path)
 578{
 579        struct stat st;
 580        char *buf, buffer[256];
 581        unsigned char sha1[20];
 582        int fd;
 583        ssize_t len;
 584
 585        if (lstat(path, &st) < 0)
 586                return -1;
 587
 588        /* Make sure it is a "refs/.." symlink */
 589        if (S_ISLNK(st.st_mode)) {
 590                len = readlink(path, buffer, sizeof(buffer)-1);
 591                if (len >= 5 && !memcmp("refs/", buffer, 5))
 592                        return 0;
 593                return -1;
 594        }
 595
 596        /*
 597         * Anything else, just open it and try to see if it is a symbolic ref.
 598         */
 599        fd = open(path, O_RDONLY);
 600        if (fd < 0)
 601                return -1;
 602        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 603        close(fd);
 604
 605        /*
 606         * Is it a symbolic ref?
 607         */
 608        if (len < 4)
 609                return -1;
 610        if (!memcmp("ref:", buffer, 4)) {
 611                buf = buffer + 4;
 612                len -= 4;
 613                while (len && isspace(*buf))
 614                        buf++, len--;
 615                if (len >= 5 && !memcmp("refs/", buf, 5))
 616                        return 0;
 617        }
 618
 619        /*
 620         * Is this a detached HEAD?
 621         */
 622        if (!get_sha1_hex(buffer, sha1))
 623                return 0;
 624
 625        return -1;
 626}
 627
 628static struct passwd *getpw_str(const char *username, size_t len)
 629{
 630        struct passwd *pw;
 631        char *username_z = xmemdupz(username, len);
 632        pw = getpwnam(username_z);
 633        free(username_z);
 634        return pw;
 635}
 636
 637/*
 638 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 639 * then it is a newly allocated string. Returns NULL on getpw failure or
 640 * if path is NULL.
 641 */
 642char *expand_user_path(const char *path)
 643{
 644        struct strbuf user_path = STRBUF_INIT;
 645        const char *to_copy = path;
 646
 647        if (path == NULL)
 648                goto return_null;
 649        if (path[0] == '~') {
 650                const char *first_slash = strchrnul(path, '/');
 651                const char *username = path + 1;
 652                size_t username_len = first_slash - username;
 653                if (username_len == 0) {
 654                        const char *home = getenv("HOME");
 655                        if (!home)
 656                                goto return_null;
 657                        strbuf_addstr(&user_path, home);
 658#ifdef GIT_WINDOWS_NATIVE
 659                        convert_slashes(user_path.buf);
 660#endif
 661                } else {
 662                        struct passwd *pw = getpw_str(username, username_len);
 663                        if (!pw)
 664                                goto return_null;
 665                        strbuf_addstr(&user_path, pw->pw_dir);
 666                }
 667                to_copy = first_slash;
 668        }
 669        strbuf_addstr(&user_path, to_copy);
 670        return strbuf_detach(&user_path, NULL);
 671return_null:
 672        strbuf_release(&user_path);
 673        return NULL;
 674}
 675
 676/*
 677 * First, one directory to try is determined by the following algorithm.
 678 *
 679 * (0) If "strict" is given, the path is used as given and no DWIM is
 680 *     done. Otherwise:
 681 * (1) "~/path" to mean path under the running user's home directory;
 682 * (2) "~user/path" to mean path under named user's home directory;
 683 * (3) "relative/path" to mean cwd relative directory; or
 684 * (4) "/absolute/path" to mean absolute directory.
 685 *
 686 * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 687 * in this order. We select the first one that is a valid git repository, and
 688 * chdir() to it. If none match, or we fail to chdir, we return NULL.
 689 *
 690 * If all goes well, we return the directory we used to chdir() (but
 691 * before ~user is expanded), avoiding getcwd() resolving symbolic
 692 * links.  User relative paths are also returned as they are given,
 693 * except DWIM suffixing.
 694 */
 695const char *enter_repo(const char *path, int strict)
 696{
 697        static struct strbuf validated_path = STRBUF_INIT;
 698        static struct strbuf used_path = STRBUF_INIT;
 699
 700        if (!path)
 701                return NULL;
 702
 703        if (!strict) {
 704                static const char *suffix[] = {
 705                        "/.git", "", ".git/.git", ".git", NULL,
 706                };
 707                const char *gitfile;
 708                int len = strlen(path);
 709                int i;
 710                while ((1 < len) && (path[len-1] == '/'))
 711                        len--;
 712
 713                /*
 714                 * We can handle arbitrary-sized buffers, but this remains as a
 715                 * sanity check on untrusted input.
 716                 */
 717                if (PATH_MAX <= len)
 718                        return NULL;
 719
 720                strbuf_reset(&used_path);
 721                strbuf_reset(&validated_path);
 722                strbuf_add(&used_path, path, len);
 723                strbuf_add(&validated_path, path, len);
 724
 725                if (used_path.buf[0] == '~') {
 726                        char *newpath = expand_user_path(used_path.buf);
 727                        if (!newpath)
 728                                return NULL;
 729                        strbuf_attach(&used_path, newpath, strlen(newpath),
 730                                      strlen(newpath));
 731                }
 732                for (i = 0; suffix[i]; i++) {
 733                        struct stat st;
 734                        size_t baselen = used_path.len;
 735                        strbuf_addstr(&used_path, suffix[i]);
 736                        if (!stat(used_path.buf, &st) &&
 737                            (S_ISREG(st.st_mode) ||
 738                            (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
 739                                strbuf_addstr(&validated_path, suffix[i]);
 740                                break;
 741                        }
 742                        strbuf_setlen(&used_path, baselen);
 743                }
 744                if (!suffix[i])
 745                        return NULL;
 746                gitfile = read_gitfile(used_path.buf);
 747                if (gitfile) {
 748                        strbuf_reset(&used_path);
 749                        strbuf_addstr(&used_path, gitfile);
 750                }
 751                if (chdir(used_path.buf))
 752                        return NULL;
 753                path = validated_path.buf;
 754        }
 755        else {
 756                const char *gitfile = read_gitfile(path);
 757                if (gitfile)
 758                        path = gitfile;
 759                if (chdir(path))
 760                        return NULL;
 761        }
 762
 763        if (is_git_directory(".")) {
 764                set_git_dir(".");
 765                check_repository_format();
 766                return path;
 767        }
 768
 769        return NULL;
 770}
 771
 772static int calc_shared_perm(int mode)
 773{
 774        int tweak;
 775
 776        if (get_shared_repository() < 0)
 777                tweak = -get_shared_repository();
 778        else
 779                tweak = get_shared_repository();
 780
 781        if (!(mode & S_IWUSR))
 782                tweak &= ~0222;
 783        if (mode & S_IXUSR)
 784                /* Copy read bits to execute bits */
 785                tweak |= (tweak & 0444) >> 2;
 786        if (get_shared_repository() < 0)
 787                mode = (mode & ~0777) | tweak;
 788        else
 789                mode |= tweak;
 790
 791        return mode;
 792}
 793
 794
 795int adjust_shared_perm(const char *path)
 796{
 797        int old_mode, new_mode;
 798
 799        if (!get_shared_repository())
 800                return 0;
 801        if (get_st_mode_bits(path, &old_mode) < 0)
 802                return -1;
 803
 804        new_mode = calc_shared_perm(old_mode);
 805        if (S_ISDIR(old_mode)) {
 806                /* Copy read bits to execute bits */
 807                new_mode |= (new_mode & 0444) >> 2;
 808                new_mode |= FORCE_DIR_SET_GID;
 809        }
 810
 811        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 812                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 813                return -2;
 814        return 0;
 815}
 816
 817void safe_create_dir(const char *dir, int share)
 818{
 819        if (mkdir(dir, 0777) < 0) {
 820                if (errno != EEXIST) {
 821                        perror(dir);
 822                        exit(1);
 823                }
 824        }
 825        else if (share && adjust_shared_perm(dir))
 826                die(_("Could not make %s writable by group"), dir);
 827}
 828
 829static int have_same_root(const char *path1, const char *path2)
 830{
 831        int is_abs1, is_abs2;
 832
 833        is_abs1 = is_absolute_path(path1);
 834        is_abs2 = is_absolute_path(path2);
 835        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 836               (!is_abs1 && !is_abs2);
 837}
 838
 839/*
 840 * Give path as relative to prefix.
 841 *
 842 * The strbuf may or may not be used, so do not assume it contains the
 843 * returned path.
 844 */
 845const char *relative_path(const char *in, const char *prefix,
 846                          struct strbuf *sb)
 847{
 848        int in_len = in ? strlen(in) : 0;
 849        int prefix_len = prefix ? strlen(prefix) : 0;
 850        int in_off = 0;
 851        int prefix_off = 0;
 852        int i = 0, j = 0;
 853
 854        if (!in_len)
 855                return "./";
 856        else if (!prefix_len)
 857                return in;
 858
 859        if (have_same_root(in, prefix))
 860                /* bypass dos_drive, for "c:" is identical to "C:" */
 861                i = j = has_dos_drive_prefix(in);
 862        else {
 863                return in;
 864        }
 865
 866        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 867                if (is_dir_sep(prefix[i])) {
 868                        while (is_dir_sep(prefix[i]))
 869                                i++;
 870                        while (is_dir_sep(in[j]))
 871                                j++;
 872                        prefix_off = i;
 873                        in_off = j;
 874                } else {
 875                        i++;
 876                        j++;
 877                }
 878        }
 879
 880        if (
 881            /* "prefix" seems like prefix of "in" */
 882            i >= prefix_len &&
 883            /*
 884             * but "/foo" is not a prefix of "/foobar"
 885             * (i.e. prefix not end with '/')
 886             */
 887            prefix_off < prefix_len) {
 888                if (j >= in_len) {
 889                        /* in="/a/b", prefix="/a/b" */
 890                        in_off = in_len;
 891                } else if (is_dir_sep(in[j])) {
 892                        /* in="/a/b/c", prefix="/a/b" */
 893                        while (is_dir_sep(in[j]))
 894                                j++;
 895                        in_off = j;
 896                } else {
 897                        /* in="/a/bbb/c", prefix="/a/b" */
 898                        i = prefix_off;
 899                }
 900        } else if (
 901                   /* "in" is short than "prefix" */
 902                   j >= in_len &&
 903                   /* "in" not end with '/' */
 904                   in_off < in_len) {
 905                if (is_dir_sep(prefix[i])) {
 906                        /* in="/a/b", prefix="/a/b/c/" */
 907                        while (is_dir_sep(prefix[i]))
 908                                i++;
 909                        in_off = in_len;
 910                }
 911        }
 912        in += in_off;
 913        in_len -= in_off;
 914
 915        if (i >= prefix_len) {
 916                if (!in_len)
 917                        return "./";
 918                else
 919                        return in;
 920        }
 921
 922        strbuf_reset(sb);
 923        strbuf_grow(sb, in_len);
 924
 925        while (i < prefix_len) {
 926                if (is_dir_sep(prefix[i])) {
 927                        strbuf_addstr(sb, "../");
 928                        while (is_dir_sep(prefix[i]))
 929                                i++;
 930                        continue;
 931                }
 932                i++;
 933        }
 934        if (!is_dir_sep(prefix[prefix_len - 1]))
 935                strbuf_addstr(sb, "../");
 936
 937        strbuf_addstr(sb, in);
 938
 939        return sb->buf;
 940}
 941
 942/*
 943 * A simpler implementation of relative_path
 944 *
 945 * Get relative path by removing "prefix" from "in". This function
 946 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 947 * to increase performance when traversing the path to work_tree.
 948 */
 949const char *remove_leading_path(const char *in, const char *prefix)
 950{
 951        static struct strbuf buf = STRBUF_INIT;
 952        int i = 0, j = 0;
 953
 954        if (!prefix || !prefix[0])
 955                return in;
 956        while (prefix[i]) {
 957                if (is_dir_sep(prefix[i])) {
 958                        if (!is_dir_sep(in[j]))
 959                                return in;
 960                        while (is_dir_sep(prefix[i]))
 961                                i++;
 962                        while (is_dir_sep(in[j]))
 963                                j++;
 964                        continue;
 965                } else if (in[j] != prefix[i]) {
 966                        return in;
 967                }
 968                i++;
 969                j++;
 970        }
 971        if (
 972            /* "/foo" is a prefix of "/foo" */
 973            in[j] &&
 974            /* "/foo" is not a prefix of "/foobar" */
 975            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 976           )
 977                return in;
 978        while (is_dir_sep(in[j]))
 979                j++;
 980
 981        strbuf_reset(&buf);
 982        if (!in[j])
 983                strbuf_addstr(&buf, ".");
 984        else
 985                strbuf_addstr(&buf, in + j);
 986        return buf.buf;
 987}
 988
 989/*
 990 * It is okay if dst == src, but they should not overlap otherwise.
 991 *
 992 * Performs the following normalizations on src, storing the result in dst:
 993 * - Ensures that components are separated by '/' (Windows only)
 994 * - Squashes sequences of '/' except "//server/share" on Windows
 995 * - Removes "." components.
 996 * - Removes ".." components, and the components the precede them.
 997 * Returns failure (non-zero) if a ".." component appears as first path
 998 * component anytime during the normalization. Otherwise, returns success (0).
 999 *
1000 * Note that this function is purely textual.  It does not follow symlinks,
1001 * verify the existence of the path, or make any system calls.
1002 *
1003 * prefix_len != NULL is for a specific case of prefix_pathspec():
1004 * assume that src == dst and src[0..prefix_len-1] is already
1005 * normalized, any time "../" eats up to the prefix_len part,
1006 * prefix_len is reduced. In the end prefix_len is the remaining
1007 * prefix that has not been overridden by user pathspec.
1008 *
1009 * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
1010 * For everything but the root folder itself, the normalized path should not
1011 * end with a '/', then the callers need to be fixed up accordingly.
1012 *
1013 */
1014int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
1015{
1016        char *dst0;
1017        const char *end;
1018
1019        /*
1020         * Copy initial part of absolute path: "/", "C:/", "//server/share/".
1021         */
1022        end = src + offset_1st_component(src);
1023        while (src < end) {
1024                char c = *src++;
1025                if (is_dir_sep(c))
1026                        c = '/';
1027                *dst++ = c;
1028        }
1029        dst0 = dst;
1030
1031        while (is_dir_sep(*src))
1032                src++;
1033
1034        for (;;) {
1035                char c = *src;
1036
1037                /*
1038                 * A path component that begins with . could be
1039                 * special:
1040                 * (1) "." and ends   -- ignore and terminate.
1041                 * (2) "./"           -- ignore them, eat slash and continue.
1042                 * (3) ".." and ends  -- strip one and terminate.
1043                 * (4) "../"          -- strip one, eat slash and continue.
1044                 */
1045                if (c == '.') {
1046                        if (!src[1]) {
1047                                /* (1) */
1048                                src++;
1049                        } else if (is_dir_sep(src[1])) {
1050                                /* (2) */
1051                                src += 2;
1052                                while (is_dir_sep(*src))
1053                                        src++;
1054                                continue;
1055                        } else if (src[1] == '.') {
1056                                if (!src[2]) {
1057                                        /* (3) */
1058                                        src += 2;
1059                                        goto up_one;
1060                                } else if (is_dir_sep(src[2])) {
1061                                        /* (4) */
1062                                        src += 3;
1063                                        while (is_dir_sep(*src))
1064                                                src++;
1065                                        goto up_one;
1066                                }
1067                        }
1068                }
1069
1070                /* copy up to the next '/', and eat all '/' */
1071                while ((c = *src++) != '\0' && !is_dir_sep(c))
1072                        *dst++ = c;
1073                if (is_dir_sep(c)) {
1074                        *dst++ = '/';
1075                        while (is_dir_sep(c))
1076                                c = *src++;
1077                        src--;
1078                } else if (!c)
1079                        break;
1080                continue;
1081
1082        up_one:
1083                /*
1084                 * dst0..dst is prefix portion, and dst[-1] is '/';
1085                 * go up one level.
1086                 */
1087                dst--;  /* go to trailing '/' */
1088                if (dst <= dst0)
1089                        return -1;
1090                /* Windows: dst[-1] cannot be backslash anymore */
1091                while (dst0 < dst && dst[-1] != '/')
1092                        dst--;
1093                if (prefix_len && *prefix_len > dst - dst0)
1094                        *prefix_len = dst - dst0;
1095        }
1096        *dst = '\0';
1097        return 0;
1098}
1099
1100int normalize_path_copy(char *dst, const char *src)
1101{
1102        return normalize_path_copy_len(dst, src, NULL);
1103}
1104
1105/*
1106 * path = Canonical absolute path
1107 * prefixes = string_list containing normalized, absolute paths without
1108 * trailing slashes (except for the root directory, which is denoted by "/").
1109 *
1110 * Determines, for each path in prefixes, whether the "prefix"
1111 * is an ancestor directory of path.  Returns the length of the longest
1112 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
1113 * is an ancestor.  (Note that this means 0 is returned if prefixes is
1114 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
1115 * are not considered to be their own ancestors.  path must be in a
1116 * canonical form: empty components, or "." or ".." components are not
1117 * allowed.
1118 */
1119int longest_ancestor_length(const char *path, struct string_list *prefixes)
1120{
1121        int i, max_len = -1;
1122
1123        if (!strcmp(path, "/"))
1124                return -1;
1125
1126        for (i = 0; i < prefixes->nr; i++) {
1127                const char *ceil = prefixes->items[i].string;
1128                int len = strlen(ceil);
1129
1130                if (len == 1 && ceil[0] == '/')
1131                        len = 0; /* root matches anything, with length 0 */
1132                else if (!strncmp(path, ceil, len) && path[len] == '/')
1133                        ; /* match of length len */
1134                else
1135                        continue; /* no match */
1136
1137                if (len > max_len)
1138                        max_len = len;
1139        }
1140
1141        return max_len;
1142}
1143
1144/* strip arbitrary amount of directory separators at end of path */
1145static inline int chomp_trailing_dir_sep(const char *path, int len)
1146{
1147        while (len && is_dir_sep(path[len - 1]))
1148                len--;
1149        return len;
1150}
1151
1152/*
1153 * If path ends with suffix (complete path components), returns the
1154 * part before suffix (sans trailing directory separators).
1155 * Otherwise returns NULL.
1156 */
1157char *strip_path_suffix(const char *path, const char *suffix)
1158{
1159        int path_len = strlen(path), suffix_len = strlen(suffix);
1160
1161        while (suffix_len) {
1162                if (!path_len)
1163                        return NULL;
1164
1165                if (is_dir_sep(path[path_len - 1])) {
1166                        if (!is_dir_sep(suffix[suffix_len - 1]))
1167                                return NULL;
1168                        path_len = chomp_trailing_dir_sep(path, path_len);
1169                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
1170                }
1171                else if (path[--path_len] != suffix[--suffix_len])
1172                        return NULL;
1173        }
1174
1175        if (path_len && !is_dir_sep(path[path_len - 1]))
1176                return NULL;
1177        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
1178}
1179
1180int daemon_avoid_alias(const char *p)
1181{
1182        int sl, ndot;
1183
1184        /*
1185         * This resurrects the belts and suspenders paranoia check by HPA
1186         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
1187         * does not do getcwd() based path canonicalization.
1188         *
1189         * sl becomes true immediately after seeing '/' and continues to
1190         * be true as long as dots continue after that without intervening
1191         * non-dot character.
1192         */
1193        if (!p || (*p != '/' && *p != '~'))
1194                return -1;
1195        sl = 1; ndot = 0;
1196        p++;
1197
1198        while (1) {
1199                char ch = *p++;
1200                if (sl) {
1201                        if (ch == '.')
1202                                ndot++;
1203                        else if (ch == '/') {
1204                                if (ndot < 3)
1205                                        /* reject //, /./ and /../ */
1206                                        return -1;
1207                                ndot = 0;
1208                        }
1209                        else if (ch == 0) {
1210                                if (0 < ndot && ndot < 3)
1211                                        /* reject /.$ and /..$ */
1212                                        return -1;
1213                                return 0;
1214                        }
1215                        else
1216                                sl = ndot = 0;
1217                }
1218                else if (ch == 0)
1219                        return 0;
1220                else if (ch == '/') {
1221                        sl = 1;
1222                        ndot = 0;
1223                }
1224        }
1225}
1226
1227static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
1228{
1229        if (len < skip)
1230                return 0;
1231        len -= skip;
1232        path += skip;
1233        while (len-- > 0) {
1234                char c = *(path++);
1235                if (c != ' ' && c != '.')
1236                        return 0;
1237        }
1238        return 1;
1239}
1240
1241int is_ntfs_dotgit(const char *name)
1242{
1243        int len;
1244
1245        for (len = 0; ; len++)
1246                if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
1247                        if (only_spaces_and_periods(name, len, 4) &&
1248                                        !strncasecmp(name, ".git", 4))
1249                                return 1;
1250                        if (only_spaces_and_periods(name, len, 5) &&
1251                                        !strncasecmp(name, "git~1", 5))
1252                                return 1;
1253                        if (name[len] != '\\')
1254                                return 0;
1255                        name += len + 1;
1256                        len = -1;
1257                }
1258}
1259
1260char *xdg_config_home(const char *filename)
1261{
1262        const char *home, *config_home;
1263
1264        assert(filename);
1265        config_home = getenv("XDG_CONFIG_HOME");
1266        if (config_home && *config_home)
1267                return mkpathdup("%s/git/%s", config_home, filename);
1268
1269        home = getenv("HOME");
1270        if (home)
1271                return mkpathdup("%s/.config/git/%s", home, filename);
1272        return NULL;
1273}
1274
1275char *xdg_cache_home(const char *filename)
1276{
1277        const char *home, *cache_home;
1278
1279        assert(filename);
1280        cache_home = getenv("XDG_CACHE_HOME");
1281        if (cache_home && *cache_home)
1282                return mkpathdup("%s/git/%s", cache_home, filename);
1283
1284        home = getenv("HOME");
1285        if (home)
1286                return mkpathdup("%s/.cache/git/%s", home, filename);
1287        return NULL;
1288}
1289
1290GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
1291GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
1292GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
1293GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
1294GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
1295GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
1296GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
1297GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
1298GIT_PATH_FUNC(git_path_shallow, "shallow")