path.con commit t7063: use --force-untracked-cache to speed up a bit (f178136)
   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
   9static int get_st_mode_bits(const char *path, int *mode)
  10{
  11        struct stat st;
  12        if (lstat(path, &st) < 0)
  13                return -1;
  14        *mode = st.st_mode;
  15        return 0;
  16}
  17
  18static char bad_path[] = "/bad-path/";
  19
  20static struct strbuf *get_pathname(void)
  21{
  22        static struct strbuf pathname_array[4] = {
  23                STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
  24        };
  25        static int index;
  26        struct strbuf *sb = &pathname_array[3 & ++index];
  27        strbuf_reset(sb);
  28        return sb;
  29}
  30
  31static char *cleanup_path(char *path)
  32{
  33        /* Clean it up */
  34        if (!memcmp(path, "./", 2)) {
  35                path += 2;
  36                while (*path == '/')
  37                        path++;
  38        }
  39        return path;
  40}
  41
  42static void strbuf_cleanup_path(struct strbuf *sb)
  43{
  44        char *path = cleanup_path(sb->buf);
  45        if (path > sb->buf)
  46                strbuf_remove(sb, 0, path - sb->buf);
  47}
  48
  49char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  50{
  51        va_list args;
  52        unsigned len;
  53
  54        va_start(args, fmt);
  55        len = vsnprintf(buf, n, fmt, args);
  56        va_end(args);
  57        if (len >= n) {
  58                strlcpy(buf, bad_path, n);
  59                return buf;
  60        }
  61        return cleanup_path(buf);
  62}
  63
  64static int dir_prefix(const char *buf, const char *dir)
  65{
  66        int len = strlen(dir);
  67        return !strncmp(buf, dir, len) &&
  68                (is_dir_sep(buf[len]) || buf[len] == '\0');
  69}
  70
  71/* $buf =~ m|$dir/+$file| but without regex */
  72static int is_dir_file(const char *buf, const char *dir, const char *file)
  73{
  74        int len = strlen(dir);
  75        if (strncmp(buf, dir, len) || !is_dir_sep(buf[len]))
  76                return 0;
  77        while (is_dir_sep(buf[len]))
  78                len++;
  79        return !strcmp(buf + len, file);
  80}
  81
  82static void replace_dir(struct strbuf *buf, int len, const char *newdir)
  83{
  84        int newlen = strlen(newdir);
  85        int need_sep = (buf->buf[len] && !is_dir_sep(buf->buf[len])) &&
  86                !is_dir_sep(newdir[newlen - 1]);
  87        if (need_sep)
  88                len--;   /* keep one char, to be replaced with '/'  */
  89        strbuf_splice(buf, 0, len, newdir, newlen);
  90        if (need_sep)
  91                buf->buf[newlen] = '/';
  92}
  93
  94static const char *common_list[] = {
  95        "/branches", "/hooks", "/info", "!/logs", "/lost-found",
  96        "/objects", "/refs", "/remotes", "/worktrees", "/rr-cache", "/svn",
  97        "config", "!gc.pid", "packed-refs", "shallow",
  98        NULL
  99};
 100
 101static void update_common_dir(struct strbuf *buf, int git_dir_len)
 102{
 103        char *base = buf->buf + git_dir_len;
 104        const char **p;
 105
 106        if (is_dir_file(base, "logs", "HEAD") ||
 107            is_dir_file(base, "info", "sparse-checkout"))
 108                return; /* keep this in $GIT_DIR */
 109        for (p = common_list; *p; p++) {
 110                const char *path = *p;
 111                int is_dir = 0;
 112                if (*path == '!')
 113                        path++;
 114                if (*path == '/') {
 115                        path++;
 116                        is_dir = 1;
 117                }
 118                if (is_dir && dir_prefix(base, path)) {
 119                        replace_dir(buf, git_dir_len, get_git_common_dir());
 120                        return;
 121                }
 122                if (!is_dir && !strcmp(base, path)) {
 123                        replace_dir(buf, git_dir_len, get_git_common_dir());
 124                        return;
 125                }
 126        }
 127}
 128
 129void report_linked_checkout_garbage(void)
 130{
 131        struct strbuf sb = STRBUF_INIT;
 132        const char **p;
 133        int len;
 134
 135        if (!git_common_dir_env)
 136                return;
 137        strbuf_addf(&sb, "%s/", get_git_dir());
 138        len = sb.len;
 139        for (p = common_list; *p; p++) {
 140                const char *path = *p;
 141                if (*path == '!')
 142                        continue;
 143                strbuf_setlen(&sb, len);
 144                strbuf_addstr(&sb, path);
 145                if (file_exists(sb.buf))
 146                        report_garbage("unused in linked checkout", sb.buf);
 147        }
 148        strbuf_release(&sb);
 149}
 150
 151static void adjust_git_path(struct strbuf *buf, int git_dir_len)
 152{
 153        const char *base = buf->buf + git_dir_len;
 154        if (git_graft_env && is_dir_file(base, "info", "grafts"))
 155                strbuf_splice(buf, 0, buf->len,
 156                              get_graft_file(), strlen(get_graft_file()));
 157        else if (git_index_env && !strcmp(base, "index"))
 158                strbuf_splice(buf, 0, buf->len,
 159                              get_index_file(), strlen(get_index_file()));
 160        else if (git_db_env && dir_prefix(base, "objects"))
 161                replace_dir(buf, git_dir_len + 7, get_object_directory());
 162        else if (git_common_dir_env)
 163                update_common_dir(buf, git_dir_len);
 164}
 165
 166static void do_git_path(struct strbuf *buf, const char *fmt, va_list args)
 167{
 168        int gitdir_len;
 169        strbuf_addstr(buf, get_git_dir());
 170        if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 171                strbuf_addch(buf, '/');
 172        gitdir_len = buf->len;
 173        strbuf_vaddf(buf, fmt, args);
 174        adjust_git_path(buf, gitdir_len);
 175        strbuf_cleanup_path(buf);
 176}
 177
 178void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 179{
 180        va_list args;
 181        va_start(args, fmt);
 182        do_git_path(sb, fmt, args);
 183        va_end(args);
 184}
 185
 186const char *git_path(const char *fmt, ...)
 187{
 188        struct strbuf *pathname = get_pathname();
 189        va_list args;
 190        va_start(args, fmt);
 191        do_git_path(pathname, fmt, args);
 192        va_end(args);
 193        return pathname->buf;
 194}
 195
 196char *git_pathdup(const char *fmt, ...)
 197{
 198        struct strbuf path = STRBUF_INIT;
 199        va_list args;
 200        va_start(args, fmt);
 201        do_git_path(&path, fmt, args);
 202        va_end(args);
 203        return strbuf_detach(&path, NULL);
 204}
 205
 206char *mkpathdup(const char *fmt, ...)
 207{
 208        struct strbuf sb = STRBUF_INIT;
 209        va_list args;
 210        va_start(args, fmt);
 211        strbuf_vaddf(&sb, fmt, args);
 212        va_end(args);
 213        strbuf_cleanup_path(&sb);
 214        return strbuf_detach(&sb, NULL);
 215}
 216
 217const char *mkpath(const char *fmt, ...)
 218{
 219        va_list args;
 220        struct strbuf *pathname = get_pathname();
 221        va_start(args, fmt);
 222        strbuf_vaddf(pathname, fmt, args);
 223        va_end(args);
 224        return cleanup_path(pathname->buf);
 225}
 226
 227const char *git_path_submodule(const char *path, const char *fmt, ...)
 228{
 229        struct strbuf *buf = get_pathname();
 230        const char *git_dir;
 231        va_list args;
 232
 233        strbuf_addstr(buf, path);
 234        if (buf->len && buf->buf[buf->len - 1] != '/')
 235                strbuf_addch(buf, '/');
 236        strbuf_addstr(buf, ".git");
 237
 238        git_dir = read_gitfile(buf->buf);
 239        if (git_dir) {
 240                strbuf_reset(buf);
 241                strbuf_addstr(buf, git_dir);
 242        }
 243        strbuf_addch(buf, '/');
 244
 245        va_start(args, fmt);
 246        strbuf_vaddf(buf, fmt, args);
 247        va_end(args);
 248        strbuf_cleanup_path(buf);
 249        return buf->buf;
 250}
 251
 252int validate_headref(const char *path)
 253{
 254        struct stat st;
 255        char *buf, buffer[256];
 256        unsigned char sha1[20];
 257        int fd;
 258        ssize_t len;
 259
 260        if (lstat(path, &st) < 0)
 261                return -1;
 262
 263        /* Make sure it is a "refs/.." symlink */
 264        if (S_ISLNK(st.st_mode)) {
 265                len = readlink(path, buffer, sizeof(buffer)-1);
 266                if (len >= 5 && !memcmp("refs/", buffer, 5))
 267                        return 0;
 268                return -1;
 269        }
 270
 271        /*
 272         * Anything else, just open it and try to see if it is a symbolic ref.
 273         */
 274        fd = open(path, O_RDONLY);
 275        if (fd < 0)
 276                return -1;
 277        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 278        close(fd);
 279
 280        /*
 281         * Is it a symbolic ref?
 282         */
 283        if (len < 4)
 284                return -1;
 285        if (!memcmp("ref:", buffer, 4)) {
 286                buf = buffer + 4;
 287                len -= 4;
 288                while (len && isspace(*buf))
 289                        buf++, len--;
 290                if (len >= 5 && !memcmp("refs/", buf, 5))
 291                        return 0;
 292        }
 293
 294        /*
 295         * Is this a detached HEAD?
 296         */
 297        if (!get_sha1_hex(buffer, sha1))
 298                return 0;
 299
 300        return -1;
 301}
 302
 303static struct passwd *getpw_str(const char *username, size_t len)
 304{
 305        struct passwd *pw;
 306        char *username_z = xmemdupz(username, len);
 307        pw = getpwnam(username_z);
 308        free(username_z);
 309        return pw;
 310}
 311
 312/*
 313 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 314 * then it is a newly allocated string. Returns NULL on getpw failure or
 315 * if path is NULL.
 316 */
 317char *expand_user_path(const char *path)
 318{
 319        struct strbuf user_path = STRBUF_INIT;
 320        const char *to_copy = path;
 321
 322        if (path == NULL)
 323                goto return_null;
 324        if (path[0] == '~') {
 325                const char *first_slash = strchrnul(path, '/');
 326                const char *username = path + 1;
 327                size_t username_len = first_slash - username;
 328                if (username_len == 0) {
 329                        const char *home = getenv("HOME");
 330                        if (!home)
 331                                goto return_null;
 332                        strbuf_addstr(&user_path, home);
 333                } else {
 334                        struct passwd *pw = getpw_str(username, username_len);
 335                        if (!pw)
 336                                goto return_null;
 337                        strbuf_addstr(&user_path, pw->pw_dir);
 338                }
 339                to_copy = first_slash;
 340        }
 341        strbuf_addstr(&user_path, to_copy);
 342        return strbuf_detach(&user_path, NULL);
 343return_null:
 344        strbuf_release(&user_path);
 345        return NULL;
 346}
 347
 348/*
 349 * First, one directory to try is determined by the following algorithm.
 350 *
 351 * (0) If "strict" is given, the path is used as given and no DWIM is
 352 *     done. Otherwise:
 353 * (1) "~/path" to mean path under the running user's home directory;
 354 * (2) "~user/path" to mean path under named user's home directory;
 355 * (3) "relative/path" to mean cwd relative directory; or
 356 * (4) "/absolute/path" to mean absolute directory.
 357 *
 358 * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 359 * in this order. We select the first one that is a valid git repository, and
 360 * chdir() to it. If none match, or we fail to chdir, we return NULL.
 361 *
 362 * If all goes well, we return the directory we used to chdir() (but
 363 * before ~user is expanded), avoiding getcwd() resolving symbolic
 364 * links.  User relative paths are also returned as they are given,
 365 * except DWIM suffixing.
 366 */
 367const char *enter_repo(const char *path, int strict)
 368{
 369        static char used_path[PATH_MAX];
 370        static char validated_path[PATH_MAX];
 371
 372        if (!path)
 373                return NULL;
 374
 375        if (!strict) {
 376                static const char *suffix[] = {
 377                        "/.git", "", ".git/.git", ".git", NULL,
 378                };
 379                const char *gitfile;
 380                int len = strlen(path);
 381                int i;
 382                while ((1 < len) && (path[len-1] == '/'))
 383                        len--;
 384
 385                if (PATH_MAX <= len)
 386                        return NULL;
 387                strncpy(used_path, path, len); used_path[len] = 0 ;
 388                strcpy(validated_path, used_path);
 389
 390                if (used_path[0] == '~') {
 391                        char *newpath = expand_user_path(used_path);
 392                        if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 393                                free(newpath);
 394                                return NULL;
 395                        }
 396                        /*
 397                         * Copy back into the static buffer. A pity
 398                         * since newpath was not bounded, but other
 399                         * branches of the if are limited by PATH_MAX
 400                         * anyway.
 401                         */
 402                        strcpy(used_path, newpath); free(newpath);
 403                }
 404                else if (PATH_MAX - 10 < len)
 405                        return NULL;
 406                len = strlen(used_path);
 407                for (i = 0; suffix[i]; i++) {
 408                        struct stat st;
 409                        strcpy(used_path + len, suffix[i]);
 410                        if (!stat(used_path, &st) &&
 411                            (S_ISREG(st.st_mode) ||
 412                            (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 413                                strcat(validated_path, suffix[i]);
 414                                break;
 415                        }
 416                }
 417                if (!suffix[i])
 418                        return NULL;
 419                gitfile = read_gitfile(used_path) ;
 420                if (gitfile)
 421                        strcpy(used_path, gitfile);
 422                if (chdir(used_path))
 423                        return NULL;
 424                path = validated_path;
 425        }
 426        else if (chdir(path))
 427                return NULL;
 428
 429        if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 430            validate_headref("HEAD") == 0) {
 431                set_git_dir(".");
 432                check_repository_format();
 433                return path;
 434        }
 435
 436        return NULL;
 437}
 438
 439static int calc_shared_perm(int mode)
 440{
 441        int tweak;
 442
 443        if (shared_repository < 0)
 444                tweak = -shared_repository;
 445        else
 446                tweak = shared_repository;
 447
 448        if (!(mode & S_IWUSR))
 449                tweak &= ~0222;
 450        if (mode & S_IXUSR)
 451                /* Copy read bits to execute bits */
 452                tweak |= (tweak & 0444) >> 2;
 453        if (shared_repository < 0)
 454                mode = (mode & ~0777) | tweak;
 455        else
 456                mode |= tweak;
 457
 458        return mode;
 459}
 460
 461
 462int adjust_shared_perm(const char *path)
 463{
 464        int old_mode, new_mode;
 465
 466        if (!shared_repository)
 467                return 0;
 468        if (get_st_mode_bits(path, &old_mode) < 0)
 469                return -1;
 470
 471        new_mode = calc_shared_perm(old_mode);
 472        if (S_ISDIR(old_mode)) {
 473                /* Copy read bits to execute bits */
 474                new_mode |= (new_mode & 0444) >> 2;
 475                new_mode |= FORCE_DIR_SET_GID;
 476        }
 477
 478        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 479                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 480                return -2;
 481        return 0;
 482}
 483
 484static int have_same_root(const char *path1, const char *path2)
 485{
 486        int is_abs1, is_abs2;
 487
 488        is_abs1 = is_absolute_path(path1);
 489        is_abs2 = is_absolute_path(path2);
 490        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 491               (!is_abs1 && !is_abs2);
 492}
 493
 494/*
 495 * Give path as relative to prefix.
 496 *
 497 * The strbuf may or may not be used, so do not assume it contains the
 498 * returned path.
 499 */
 500const char *relative_path(const char *in, const char *prefix,
 501                          struct strbuf *sb)
 502{
 503        int in_len = in ? strlen(in) : 0;
 504        int prefix_len = prefix ? strlen(prefix) : 0;
 505        int in_off = 0;
 506        int prefix_off = 0;
 507        int i = 0, j = 0;
 508
 509        if (!in_len)
 510                return "./";
 511        else if (!prefix_len)
 512                return in;
 513
 514        if (have_same_root(in, prefix)) {
 515                /* bypass dos_drive, for "c:" is identical to "C:" */
 516                if (has_dos_drive_prefix(in)) {
 517                        i = 2;
 518                        j = 2;
 519                }
 520        } else {
 521                return in;
 522        }
 523
 524        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 525                if (is_dir_sep(prefix[i])) {
 526                        while (is_dir_sep(prefix[i]))
 527                                i++;
 528                        while (is_dir_sep(in[j]))
 529                                j++;
 530                        prefix_off = i;
 531                        in_off = j;
 532                } else {
 533                        i++;
 534                        j++;
 535                }
 536        }
 537
 538        if (
 539            /* "prefix" seems like prefix of "in" */
 540            i >= prefix_len &&
 541            /*
 542             * but "/foo" is not a prefix of "/foobar"
 543             * (i.e. prefix not end with '/')
 544             */
 545            prefix_off < prefix_len) {
 546                if (j >= in_len) {
 547                        /* in="/a/b", prefix="/a/b" */
 548                        in_off = in_len;
 549                } else if (is_dir_sep(in[j])) {
 550                        /* in="/a/b/c", prefix="/a/b" */
 551                        while (is_dir_sep(in[j]))
 552                                j++;
 553                        in_off = j;
 554                } else {
 555                        /* in="/a/bbb/c", prefix="/a/b" */
 556                        i = prefix_off;
 557                }
 558        } else if (
 559                   /* "in" is short than "prefix" */
 560                   j >= in_len &&
 561                   /* "in" not end with '/' */
 562                   in_off < in_len) {
 563                if (is_dir_sep(prefix[i])) {
 564                        /* in="/a/b", prefix="/a/b/c/" */
 565                        while (is_dir_sep(prefix[i]))
 566                                i++;
 567                        in_off = in_len;
 568                }
 569        }
 570        in += in_off;
 571        in_len -= in_off;
 572
 573        if (i >= prefix_len) {
 574                if (!in_len)
 575                        return "./";
 576                else
 577                        return in;
 578        }
 579
 580        strbuf_reset(sb);
 581        strbuf_grow(sb, in_len);
 582
 583        while (i < prefix_len) {
 584                if (is_dir_sep(prefix[i])) {
 585                        strbuf_addstr(sb, "../");
 586                        while (is_dir_sep(prefix[i]))
 587                                i++;
 588                        continue;
 589                }
 590                i++;
 591        }
 592        if (!is_dir_sep(prefix[prefix_len - 1]))
 593                strbuf_addstr(sb, "../");
 594
 595        strbuf_addstr(sb, in);
 596
 597        return sb->buf;
 598}
 599
 600/*
 601 * A simpler implementation of relative_path
 602 *
 603 * Get relative path by removing "prefix" from "in". This function
 604 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 605 * to increase performance when traversing the path to work_tree.
 606 */
 607const char *remove_leading_path(const char *in, const char *prefix)
 608{
 609        static char buf[PATH_MAX + 1];
 610        int i = 0, j = 0;
 611
 612        if (!prefix || !prefix[0])
 613                return in;
 614        while (prefix[i]) {
 615                if (is_dir_sep(prefix[i])) {
 616                        if (!is_dir_sep(in[j]))
 617                                return in;
 618                        while (is_dir_sep(prefix[i]))
 619                                i++;
 620                        while (is_dir_sep(in[j]))
 621                                j++;
 622                        continue;
 623                } else if (in[j] != prefix[i]) {
 624                        return in;
 625                }
 626                i++;
 627                j++;
 628        }
 629        if (
 630            /* "/foo" is a prefix of "/foo" */
 631            in[j] &&
 632            /* "/foo" is not a prefix of "/foobar" */
 633            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 634           )
 635                return in;
 636        while (is_dir_sep(in[j]))
 637                j++;
 638        if (!in[j])
 639                strcpy(buf, ".");
 640        else
 641                strcpy(buf, in + j);
 642        return buf;
 643}
 644
 645/*
 646 * It is okay if dst == src, but they should not overlap otherwise.
 647 *
 648 * Performs the following normalizations on src, storing the result in dst:
 649 * - Ensures that components are separated by '/' (Windows only)
 650 * - Squashes sequences of '/'.
 651 * - Removes "." components.
 652 * - Removes ".." components, and the components the precede them.
 653 * Returns failure (non-zero) if a ".." component appears as first path
 654 * component anytime during the normalization. Otherwise, returns success (0).
 655 *
 656 * Note that this function is purely textual.  It does not follow symlinks,
 657 * verify the existence of the path, or make any system calls.
 658 *
 659 * prefix_len != NULL is for a specific case of prefix_pathspec():
 660 * assume that src == dst and src[0..prefix_len-1] is already
 661 * normalized, any time "../" eats up to the prefix_len part,
 662 * prefix_len is reduced. In the end prefix_len is the remaining
 663 * prefix that has not been overridden by user pathspec.
 664 */
 665int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 666{
 667        char *dst0;
 668
 669        if (has_dos_drive_prefix(src)) {
 670                *dst++ = *src++;
 671                *dst++ = *src++;
 672        }
 673        dst0 = dst;
 674
 675        if (is_dir_sep(*src)) {
 676                *dst++ = '/';
 677                while (is_dir_sep(*src))
 678                        src++;
 679        }
 680
 681        for (;;) {
 682                char c = *src;
 683
 684                /*
 685                 * A path component that begins with . could be
 686                 * special:
 687                 * (1) "." and ends   -- ignore and terminate.
 688                 * (2) "./"           -- ignore them, eat slash and continue.
 689                 * (3) ".." and ends  -- strip one and terminate.
 690                 * (4) "../"          -- strip one, eat slash and continue.
 691                 */
 692                if (c == '.') {
 693                        if (!src[1]) {
 694                                /* (1) */
 695                                src++;
 696                        } else if (is_dir_sep(src[1])) {
 697                                /* (2) */
 698                                src += 2;
 699                                while (is_dir_sep(*src))
 700                                        src++;
 701                                continue;
 702                        } else if (src[1] == '.') {
 703                                if (!src[2]) {
 704                                        /* (3) */
 705                                        src += 2;
 706                                        goto up_one;
 707                                } else if (is_dir_sep(src[2])) {
 708                                        /* (4) */
 709                                        src += 3;
 710                                        while (is_dir_sep(*src))
 711                                                src++;
 712                                        goto up_one;
 713                                }
 714                        }
 715                }
 716
 717                /* copy up to the next '/', and eat all '/' */
 718                while ((c = *src++) != '\0' && !is_dir_sep(c))
 719                        *dst++ = c;
 720                if (is_dir_sep(c)) {
 721                        *dst++ = '/';
 722                        while (is_dir_sep(c))
 723                                c = *src++;
 724                        src--;
 725                } else if (!c)
 726                        break;
 727                continue;
 728
 729        up_one:
 730                /*
 731                 * dst0..dst is prefix portion, and dst[-1] is '/';
 732                 * go up one level.
 733                 */
 734                dst--;  /* go to trailing '/' */
 735                if (dst <= dst0)
 736                        return -1;
 737                /* Windows: dst[-1] cannot be backslash anymore */
 738                while (dst0 < dst && dst[-1] != '/')
 739                        dst--;
 740                if (prefix_len && *prefix_len > dst - dst0)
 741                        *prefix_len = dst - dst0;
 742        }
 743        *dst = '\0';
 744        return 0;
 745}
 746
 747int normalize_path_copy(char *dst, const char *src)
 748{
 749        return normalize_path_copy_len(dst, src, NULL);
 750}
 751
 752/*
 753 * path = Canonical absolute path
 754 * prefixes = string_list containing normalized, absolute paths without
 755 * trailing slashes (except for the root directory, which is denoted by "/").
 756 *
 757 * Determines, for each path in prefixes, whether the "prefix"
 758 * is an ancestor directory of path.  Returns the length of the longest
 759 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 760 * is an ancestor.  (Note that this means 0 is returned if prefixes is
 761 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 762 * are not considered to be their own ancestors.  path must be in a
 763 * canonical form: empty components, or "." or ".." components are not
 764 * allowed.
 765 */
 766int longest_ancestor_length(const char *path, struct string_list *prefixes)
 767{
 768        int i, max_len = -1;
 769
 770        if (!strcmp(path, "/"))
 771                return -1;
 772
 773        for (i = 0; i < prefixes->nr; i++) {
 774                const char *ceil = prefixes->items[i].string;
 775                int len = strlen(ceil);
 776
 777                if (len == 1 && ceil[0] == '/')
 778                        len = 0; /* root matches anything, with length 0 */
 779                else if (!strncmp(path, ceil, len) && path[len] == '/')
 780                        ; /* match of length len */
 781                else
 782                        continue; /* no match */
 783
 784                if (len > max_len)
 785                        max_len = len;
 786        }
 787
 788        return max_len;
 789}
 790
 791/* strip arbitrary amount of directory separators at end of path */
 792static inline int chomp_trailing_dir_sep(const char *path, int len)
 793{
 794        while (len && is_dir_sep(path[len - 1]))
 795                len--;
 796        return len;
 797}
 798
 799/*
 800 * If path ends with suffix (complete path components), returns the
 801 * part before suffix (sans trailing directory separators).
 802 * Otherwise returns NULL.
 803 */
 804char *strip_path_suffix(const char *path, const char *suffix)
 805{
 806        int path_len = strlen(path), suffix_len = strlen(suffix);
 807
 808        while (suffix_len) {
 809                if (!path_len)
 810                        return NULL;
 811
 812                if (is_dir_sep(path[path_len - 1])) {
 813                        if (!is_dir_sep(suffix[suffix_len - 1]))
 814                                return NULL;
 815                        path_len = chomp_trailing_dir_sep(path, path_len);
 816                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 817                }
 818                else if (path[--path_len] != suffix[--suffix_len])
 819                        return NULL;
 820        }
 821
 822        if (path_len && !is_dir_sep(path[path_len - 1]))
 823                return NULL;
 824        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 825}
 826
 827int daemon_avoid_alias(const char *p)
 828{
 829        int sl, ndot;
 830
 831        /*
 832         * This resurrects the belts and suspenders paranoia check by HPA
 833         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 834         * does not do getcwd() based path canonicalization.
 835         *
 836         * sl becomes true immediately after seeing '/' and continues to
 837         * be true as long as dots continue after that without intervening
 838         * non-dot character.
 839         */
 840        if (!p || (*p != '/' && *p != '~'))
 841                return -1;
 842        sl = 1; ndot = 0;
 843        p++;
 844
 845        while (1) {
 846                char ch = *p++;
 847                if (sl) {
 848                        if (ch == '.')
 849                                ndot++;
 850                        else if (ch == '/') {
 851                                if (ndot < 3)
 852                                        /* reject //, /./ and /../ */
 853                                        return -1;
 854                                ndot = 0;
 855                        }
 856                        else if (ch == 0) {
 857                                if (0 < ndot && ndot < 3)
 858                                        /* reject /.$ and /..$ */
 859                                        return -1;
 860                                return 0;
 861                        }
 862                        else
 863                                sl = ndot = 0;
 864                }
 865                else if (ch == 0)
 866                        return 0;
 867                else if (ch == '/') {
 868                        sl = 1;
 869                        ndot = 0;
 870                }
 871        }
 872}
 873
 874static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 875{
 876        if (len < skip)
 877                return 0;
 878        len -= skip;
 879        path += skip;
 880        while (len-- > 0) {
 881                char c = *(path++);
 882                if (c != ' ' && c != '.')
 883                        return 0;
 884        }
 885        return 1;
 886}
 887
 888int is_ntfs_dotgit(const char *name)
 889{
 890        int len;
 891
 892        for (len = 0; ; len++)
 893                if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 894                        if (only_spaces_and_periods(name, len, 4) &&
 895                                        !strncasecmp(name, ".git", 4))
 896                                return 1;
 897                        if (only_spaces_and_periods(name, len, 5) &&
 898                                        !strncasecmp(name, "git~1", 5))
 899                                return 1;
 900                        if (name[len] != '\\')
 901                                return 0;
 902                        name += len + 1;
 903                        len = -1;
 904                }
 905}
 906
 907char *xdg_config_home(const char *filename)
 908{
 909        const char *home, *config_home;
 910
 911        assert(filename);
 912        config_home = getenv("XDG_CONFIG_HOME");
 913        if (config_home && *config_home)
 914                return mkpathdup("%s/git/%s", config_home, filename);
 915
 916        home = getenv("HOME");
 917        if (home)
 918                return mkpathdup("%s/.config/git/%s", home, filename);
 919        return NULL;
 920}