path.con commit doc: revisions - clarify reachability examples (1afe13b)
   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, const char *common_dir)
 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
 119                if (!common_dir)
 120                        common_dir = get_git_common_dir();
 121
 122                if (is_dir && dir_prefix(base, path)) {
 123                        replace_dir(buf, git_dir_len, common_dir);
 124                        return;
 125                }
 126                if (!is_dir && !strcmp(base, path)) {
 127                        replace_dir(buf, git_dir_len, common_dir);
 128                        return;
 129                }
 130        }
 131}
 132
 133void report_linked_checkout_garbage(void)
 134{
 135        struct strbuf sb = STRBUF_INIT;
 136        const char **p;
 137        int len;
 138
 139        if (!git_common_dir_env)
 140                return;
 141        strbuf_addf(&sb, "%s/", get_git_dir());
 142        len = sb.len;
 143        for (p = common_list; *p; p++) {
 144                const char *path = *p;
 145                if (*path == '!')
 146                        continue;
 147                strbuf_setlen(&sb, len);
 148                strbuf_addstr(&sb, path);
 149                if (file_exists(sb.buf))
 150                        report_garbage(PACKDIR_FILE_GARBAGE, sb.buf);
 151        }
 152        strbuf_release(&sb);
 153}
 154
 155static void adjust_git_path(struct strbuf *buf, int git_dir_len)
 156{
 157        const char *base = buf->buf + git_dir_len;
 158        if (git_graft_env && is_dir_file(base, "info", "grafts"))
 159                strbuf_splice(buf, 0, buf->len,
 160                              get_graft_file(), strlen(get_graft_file()));
 161        else if (git_index_env && !strcmp(base, "index"))
 162                strbuf_splice(buf, 0, buf->len,
 163                              get_index_file(), strlen(get_index_file()));
 164        else if (git_db_env && dir_prefix(base, "objects"))
 165                replace_dir(buf, git_dir_len + 7, get_object_directory());
 166        else if (git_common_dir_env)
 167                update_common_dir(buf, git_dir_len, NULL);
 168}
 169
 170static void do_git_path(struct strbuf *buf, const char *fmt, va_list args)
 171{
 172        int gitdir_len;
 173        strbuf_addstr(buf, get_git_dir());
 174        if (buf->len && !is_dir_sep(buf->buf[buf->len - 1]))
 175                strbuf_addch(buf, '/');
 176        gitdir_len = buf->len;
 177        strbuf_vaddf(buf, fmt, args);
 178        adjust_git_path(buf, gitdir_len);
 179        strbuf_cleanup_path(buf);
 180}
 181
 182void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 183{
 184        va_list args;
 185        va_start(args, fmt);
 186        do_git_path(sb, fmt, args);
 187        va_end(args);
 188}
 189
 190const char *git_path(const char *fmt, ...)
 191{
 192        struct strbuf *pathname = get_pathname();
 193        va_list args;
 194        va_start(args, fmt);
 195        do_git_path(pathname, fmt, args);
 196        va_end(args);
 197        return pathname->buf;
 198}
 199
 200char *git_pathdup(const char *fmt, ...)
 201{
 202        struct strbuf path = STRBUF_INIT;
 203        va_list args;
 204        va_start(args, fmt);
 205        do_git_path(&path, fmt, args);
 206        va_end(args);
 207        return strbuf_detach(&path, NULL);
 208}
 209
 210char *mkpathdup(const char *fmt, ...)
 211{
 212        struct strbuf sb = STRBUF_INIT;
 213        va_list args;
 214        va_start(args, fmt);
 215        strbuf_vaddf(&sb, fmt, args);
 216        va_end(args);
 217        strbuf_cleanup_path(&sb);
 218        return strbuf_detach(&sb, NULL);
 219}
 220
 221const char *mkpath(const char *fmt, ...)
 222{
 223        va_list args;
 224        struct strbuf *pathname = get_pathname();
 225        va_start(args, fmt);
 226        strbuf_vaddf(pathname, fmt, args);
 227        va_end(args);
 228        return cleanup_path(pathname->buf);
 229}
 230
 231static void do_submodule_path(struct strbuf *buf, const char *path,
 232                              const char *fmt, va_list args)
 233{
 234        const char *git_dir;
 235        struct strbuf git_submodule_common_dir = STRBUF_INIT;
 236        struct strbuf git_submodule_dir = STRBUF_INIT;
 237
 238        strbuf_addstr(buf, path);
 239        if (buf->len && buf->buf[buf->len - 1] != '/')
 240                strbuf_addch(buf, '/');
 241        strbuf_addstr(buf, ".git");
 242
 243        git_dir = read_gitfile(buf->buf);
 244        if (git_dir) {
 245                strbuf_reset(buf);
 246                strbuf_addstr(buf, git_dir);
 247        }
 248        strbuf_addch(buf, '/');
 249        strbuf_addstr(&git_submodule_dir, buf->buf);
 250
 251        strbuf_vaddf(buf, fmt, args);
 252
 253        if (get_common_dir_noenv(&git_submodule_common_dir, git_submodule_dir.buf))
 254                update_common_dir(buf, git_submodule_dir.len, git_submodule_common_dir.buf);
 255
 256        strbuf_cleanup_path(buf);
 257
 258        strbuf_release(&git_submodule_dir);
 259        strbuf_release(&git_submodule_common_dir);
 260}
 261
 262char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 263{
 264        va_list args;
 265        struct strbuf buf = STRBUF_INIT;
 266        va_start(args, fmt);
 267        do_submodule_path(&buf, path, fmt, args);
 268        va_end(args);
 269        return strbuf_detach(&buf, NULL);
 270}
 271
 272void strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 273                               const char *fmt, ...)
 274{
 275        va_list args;
 276        va_start(args, fmt);
 277        do_submodule_path(buf, path, fmt, args);
 278        va_end(args);
 279}
 280
 281int validate_headref(const char *path)
 282{
 283        struct stat st;
 284        char *buf, buffer[256];
 285        unsigned char sha1[20];
 286        int fd;
 287        ssize_t len;
 288
 289        if (lstat(path, &st) < 0)
 290                return -1;
 291
 292        /* Make sure it is a "refs/.." symlink */
 293        if (S_ISLNK(st.st_mode)) {
 294                len = readlink(path, buffer, sizeof(buffer)-1);
 295                if (len >= 5 && !memcmp("refs/", buffer, 5))
 296                        return 0;
 297                return -1;
 298        }
 299
 300        /*
 301         * Anything else, just open it and try to see if it is a symbolic ref.
 302         */
 303        fd = open(path, O_RDONLY);
 304        if (fd < 0)
 305                return -1;
 306        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 307        close(fd);
 308
 309        /*
 310         * Is it a symbolic ref?
 311         */
 312        if (len < 4)
 313                return -1;
 314        if (!memcmp("ref:", buffer, 4)) {
 315                buf = buffer + 4;
 316                len -= 4;
 317                while (len && isspace(*buf))
 318                        buf++, len--;
 319                if (len >= 5 && !memcmp("refs/", buf, 5))
 320                        return 0;
 321        }
 322
 323        /*
 324         * Is this a detached HEAD?
 325         */
 326        if (!get_sha1_hex(buffer, sha1))
 327                return 0;
 328
 329        return -1;
 330}
 331
 332static struct passwd *getpw_str(const char *username, size_t len)
 333{
 334        struct passwd *pw;
 335        char *username_z = xmemdupz(username, len);
 336        pw = getpwnam(username_z);
 337        free(username_z);
 338        return pw;
 339}
 340
 341/*
 342 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 343 * then it is a newly allocated string. Returns NULL on getpw failure or
 344 * if path is NULL.
 345 */
 346char *expand_user_path(const char *path)
 347{
 348        struct strbuf user_path = STRBUF_INIT;
 349        const char *to_copy = path;
 350
 351        if (path == NULL)
 352                goto return_null;
 353        if (path[0] == '~') {
 354                const char *first_slash = strchrnul(path, '/');
 355                const char *username = path + 1;
 356                size_t username_len = first_slash - username;
 357                if (username_len == 0) {
 358                        const char *home = getenv("HOME");
 359                        if (!home)
 360                                goto return_null;
 361                        strbuf_addstr(&user_path, home);
 362                } else {
 363                        struct passwd *pw = getpw_str(username, username_len);
 364                        if (!pw)
 365                                goto return_null;
 366                        strbuf_addstr(&user_path, pw->pw_dir);
 367                }
 368                to_copy = first_slash;
 369        }
 370        strbuf_addstr(&user_path, to_copy);
 371        return strbuf_detach(&user_path, NULL);
 372return_null:
 373        strbuf_release(&user_path);
 374        return NULL;
 375}
 376
 377/*
 378 * First, one directory to try is determined by the following algorithm.
 379 *
 380 * (0) If "strict" is given, the path is used as given and no DWIM is
 381 *     done. Otherwise:
 382 * (1) "~/path" to mean path under the running user's home directory;
 383 * (2) "~user/path" to mean path under named user's home directory;
 384 * (3) "relative/path" to mean cwd relative directory; or
 385 * (4) "/absolute/path" to mean absolute directory.
 386 *
 387 * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 388 * in this order. We select the first one that is a valid git repository, and
 389 * chdir() to it. If none match, or we fail to chdir, we return NULL.
 390 *
 391 * If all goes well, we return the directory we used to chdir() (but
 392 * before ~user is expanded), avoiding getcwd() resolving symbolic
 393 * links.  User relative paths are also returned as they are given,
 394 * except DWIM suffixing.
 395 */
 396const char *enter_repo(const char *path, int strict)
 397{
 398        static char used_path[PATH_MAX];
 399        static char validated_path[PATH_MAX];
 400
 401        if (!path)
 402                return NULL;
 403
 404        if (!strict) {
 405                static const char *suffix[] = {
 406                        "/.git", "", ".git/.git", ".git", NULL,
 407                };
 408                const char *gitfile;
 409                int len = strlen(path);
 410                int i;
 411                while ((1 < len) && (path[len-1] == '/'))
 412                        len--;
 413
 414                if (PATH_MAX <= len)
 415                        return NULL;
 416                strncpy(used_path, path, len); used_path[len] = 0 ;
 417                strcpy(validated_path, used_path);
 418
 419                if (used_path[0] == '~') {
 420                        char *newpath = expand_user_path(used_path);
 421                        if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 422                                free(newpath);
 423                                return NULL;
 424                        }
 425                        /*
 426                         * Copy back into the static buffer. A pity
 427                         * since newpath was not bounded, but other
 428                         * branches of the if are limited by PATH_MAX
 429                         * anyway.
 430                         */
 431                        strcpy(used_path, newpath); free(newpath);
 432                }
 433                else if (PATH_MAX - 10 < len)
 434                        return NULL;
 435                len = strlen(used_path);
 436                for (i = 0; suffix[i]; i++) {
 437                        struct stat st;
 438                        strcpy(used_path + len, suffix[i]);
 439                        if (!stat(used_path, &st) &&
 440                            (S_ISREG(st.st_mode) ||
 441                            (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 442                                strcat(validated_path, suffix[i]);
 443                                break;
 444                        }
 445                }
 446                if (!suffix[i])
 447                        return NULL;
 448                gitfile = read_gitfile(used_path);
 449                if (gitfile)
 450                        strcpy(used_path, gitfile);
 451                if (chdir(used_path))
 452                        return NULL;
 453                path = validated_path;
 454        }
 455        else {
 456                const char *gitfile = read_gitfile(path);
 457                if (gitfile)
 458                        path = gitfile;
 459                if (chdir(path))
 460                        return NULL;
 461        }
 462
 463        if (is_git_directory(".")) {
 464                set_git_dir(".");
 465                check_repository_format();
 466                return path;
 467        }
 468
 469        return NULL;
 470}
 471
 472static int calc_shared_perm(int mode)
 473{
 474        int tweak;
 475
 476        if (shared_repository < 0)
 477                tweak = -shared_repository;
 478        else
 479                tweak = shared_repository;
 480
 481        if (!(mode & S_IWUSR))
 482                tweak &= ~0222;
 483        if (mode & S_IXUSR)
 484                /* Copy read bits to execute bits */
 485                tweak |= (tweak & 0444) >> 2;
 486        if (shared_repository < 0)
 487                mode = (mode & ~0777) | tweak;
 488        else
 489                mode |= tweak;
 490
 491        return mode;
 492}
 493
 494
 495int adjust_shared_perm(const char *path)
 496{
 497        int old_mode, new_mode;
 498
 499        if (!shared_repository)
 500                return 0;
 501        if (get_st_mode_bits(path, &old_mode) < 0)
 502                return -1;
 503
 504        new_mode = calc_shared_perm(old_mode);
 505        if (S_ISDIR(old_mode)) {
 506                /* Copy read bits to execute bits */
 507                new_mode |= (new_mode & 0444) >> 2;
 508                new_mode |= FORCE_DIR_SET_GID;
 509        }
 510
 511        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 512                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 513                return -2;
 514        return 0;
 515}
 516
 517static int have_same_root(const char *path1, const char *path2)
 518{
 519        int is_abs1, is_abs2;
 520
 521        is_abs1 = is_absolute_path(path1);
 522        is_abs2 = is_absolute_path(path2);
 523        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 524               (!is_abs1 && !is_abs2);
 525}
 526
 527/*
 528 * Give path as relative to prefix.
 529 *
 530 * The strbuf may or may not be used, so do not assume it contains the
 531 * returned path.
 532 */
 533const char *relative_path(const char *in, const char *prefix,
 534                          struct strbuf *sb)
 535{
 536        int in_len = in ? strlen(in) : 0;
 537        int prefix_len = prefix ? strlen(prefix) : 0;
 538        int in_off = 0;
 539        int prefix_off = 0;
 540        int i = 0, j = 0;
 541
 542        if (!in_len)
 543                return "./";
 544        else if (!prefix_len)
 545                return in;
 546
 547        if (have_same_root(in, prefix)) {
 548                /* bypass dos_drive, for "c:" is identical to "C:" */
 549                if (has_dos_drive_prefix(in)) {
 550                        i = 2;
 551                        j = 2;
 552                }
 553        } else {
 554                return in;
 555        }
 556
 557        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 558                if (is_dir_sep(prefix[i])) {
 559                        while (is_dir_sep(prefix[i]))
 560                                i++;
 561                        while (is_dir_sep(in[j]))
 562                                j++;
 563                        prefix_off = i;
 564                        in_off = j;
 565                } else {
 566                        i++;
 567                        j++;
 568                }
 569        }
 570
 571        if (
 572            /* "prefix" seems like prefix of "in" */
 573            i >= prefix_len &&
 574            /*
 575             * but "/foo" is not a prefix of "/foobar"
 576             * (i.e. prefix not end with '/')
 577             */
 578            prefix_off < prefix_len) {
 579                if (j >= in_len) {
 580                        /* in="/a/b", prefix="/a/b" */
 581                        in_off = in_len;
 582                } else if (is_dir_sep(in[j])) {
 583                        /* in="/a/b/c", prefix="/a/b" */
 584                        while (is_dir_sep(in[j]))
 585                                j++;
 586                        in_off = j;
 587                } else {
 588                        /* in="/a/bbb/c", prefix="/a/b" */
 589                        i = prefix_off;
 590                }
 591        } else if (
 592                   /* "in" is short than "prefix" */
 593                   j >= in_len &&
 594                   /* "in" not end with '/' */
 595                   in_off < in_len) {
 596                if (is_dir_sep(prefix[i])) {
 597                        /* in="/a/b", prefix="/a/b/c/" */
 598                        while (is_dir_sep(prefix[i]))
 599                                i++;
 600                        in_off = in_len;
 601                }
 602        }
 603        in += in_off;
 604        in_len -= in_off;
 605
 606        if (i >= prefix_len) {
 607                if (!in_len)
 608                        return "./";
 609                else
 610                        return in;
 611        }
 612
 613        strbuf_reset(sb);
 614        strbuf_grow(sb, in_len);
 615
 616        while (i < prefix_len) {
 617                if (is_dir_sep(prefix[i])) {
 618                        strbuf_addstr(sb, "../");
 619                        while (is_dir_sep(prefix[i]))
 620                                i++;
 621                        continue;
 622                }
 623                i++;
 624        }
 625        if (!is_dir_sep(prefix[prefix_len - 1]))
 626                strbuf_addstr(sb, "../");
 627
 628        strbuf_addstr(sb, in);
 629
 630        return sb->buf;
 631}
 632
 633/*
 634 * A simpler implementation of relative_path
 635 *
 636 * Get relative path by removing "prefix" from "in". This function
 637 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 638 * to increase performance when traversing the path to work_tree.
 639 */
 640const char *remove_leading_path(const char *in, const char *prefix)
 641{
 642        static char buf[PATH_MAX + 1];
 643        int i = 0, j = 0;
 644
 645        if (!prefix || !prefix[0])
 646                return in;
 647        while (prefix[i]) {
 648                if (is_dir_sep(prefix[i])) {
 649                        if (!is_dir_sep(in[j]))
 650                                return in;
 651                        while (is_dir_sep(prefix[i]))
 652                                i++;
 653                        while (is_dir_sep(in[j]))
 654                                j++;
 655                        continue;
 656                } else if (in[j] != prefix[i]) {
 657                        return in;
 658                }
 659                i++;
 660                j++;
 661        }
 662        if (
 663            /* "/foo" is a prefix of "/foo" */
 664            in[j] &&
 665            /* "/foo" is not a prefix of "/foobar" */
 666            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 667           )
 668                return in;
 669        while (is_dir_sep(in[j]))
 670                j++;
 671        if (!in[j])
 672                strcpy(buf, ".");
 673        else
 674                strcpy(buf, in + j);
 675        return buf;
 676}
 677
 678/*
 679 * It is okay if dst == src, but they should not overlap otherwise.
 680 *
 681 * Performs the following normalizations on src, storing the result in dst:
 682 * - Ensures that components are separated by '/' (Windows only)
 683 * - Squashes sequences of '/'.
 684 * - Removes "." components.
 685 * - Removes ".." components, and the components the precede them.
 686 * Returns failure (non-zero) if a ".." component appears as first path
 687 * component anytime during the normalization. Otherwise, returns success (0).
 688 *
 689 * Note that this function is purely textual.  It does not follow symlinks,
 690 * verify the existence of the path, or make any system calls.
 691 *
 692 * prefix_len != NULL is for a specific case of prefix_pathspec():
 693 * assume that src == dst and src[0..prefix_len-1] is already
 694 * normalized, any time "../" eats up to the prefix_len part,
 695 * prefix_len is reduced. In the end prefix_len is the remaining
 696 * prefix that has not been overridden by user pathspec.
 697 *
 698 * NEEDSWORK: This function doesn't perform normalization w.r.t. trailing '/'.
 699 * For everything but the root folder itself, the normalized path should not
 700 * end with a '/', then the callers need to be fixed up accordingly.
 701 *
 702 */
 703int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 704{
 705        char *dst0;
 706
 707        if (has_dos_drive_prefix(src)) {
 708                *dst++ = *src++;
 709                *dst++ = *src++;
 710        }
 711        dst0 = dst;
 712
 713        if (is_dir_sep(*src)) {
 714                *dst++ = '/';
 715                while (is_dir_sep(*src))
 716                        src++;
 717        }
 718
 719        for (;;) {
 720                char c = *src;
 721
 722                /*
 723                 * A path component that begins with . could be
 724                 * special:
 725                 * (1) "." and ends   -- ignore and terminate.
 726                 * (2) "./"           -- ignore them, eat slash and continue.
 727                 * (3) ".." and ends  -- strip one and terminate.
 728                 * (4) "../"          -- strip one, eat slash and continue.
 729                 */
 730                if (c == '.') {
 731                        if (!src[1]) {
 732                                /* (1) */
 733                                src++;
 734                        } else if (is_dir_sep(src[1])) {
 735                                /* (2) */
 736                                src += 2;
 737                                while (is_dir_sep(*src))
 738                                        src++;
 739                                continue;
 740                        } else if (src[1] == '.') {
 741                                if (!src[2]) {
 742                                        /* (3) */
 743                                        src += 2;
 744                                        goto up_one;
 745                                } else if (is_dir_sep(src[2])) {
 746                                        /* (4) */
 747                                        src += 3;
 748                                        while (is_dir_sep(*src))
 749                                                src++;
 750                                        goto up_one;
 751                                }
 752                        }
 753                }
 754
 755                /* copy up to the next '/', and eat all '/' */
 756                while ((c = *src++) != '\0' && !is_dir_sep(c))
 757                        *dst++ = c;
 758                if (is_dir_sep(c)) {
 759                        *dst++ = '/';
 760                        while (is_dir_sep(c))
 761                                c = *src++;
 762                        src--;
 763                } else if (!c)
 764                        break;
 765                continue;
 766
 767        up_one:
 768                /*
 769                 * dst0..dst is prefix portion, and dst[-1] is '/';
 770                 * go up one level.
 771                 */
 772                dst--;  /* go to trailing '/' */
 773                if (dst <= dst0)
 774                        return -1;
 775                /* Windows: dst[-1] cannot be backslash anymore */
 776                while (dst0 < dst && dst[-1] != '/')
 777                        dst--;
 778                if (prefix_len && *prefix_len > dst - dst0)
 779                        *prefix_len = dst - dst0;
 780        }
 781        *dst = '\0';
 782        return 0;
 783}
 784
 785int normalize_path_copy(char *dst, const char *src)
 786{
 787        return normalize_path_copy_len(dst, src, NULL);
 788}
 789
 790/*
 791 * path = Canonical absolute path
 792 * prefixes = string_list containing normalized, absolute paths without
 793 * trailing slashes (except for the root directory, which is denoted by "/").
 794 *
 795 * Determines, for each path in prefixes, whether the "prefix"
 796 * is an ancestor directory of path.  Returns the length of the longest
 797 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 798 * is an ancestor.  (Note that this means 0 is returned if prefixes is
 799 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 800 * are not considered to be their own ancestors.  path must be in a
 801 * canonical form: empty components, or "." or ".." components are not
 802 * allowed.
 803 */
 804int longest_ancestor_length(const char *path, struct string_list *prefixes)
 805{
 806        int i, max_len = -1;
 807
 808        if (!strcmp(path, "/"))
 809                return -1;
 810
 811        for (i = 0; i < prefixes->nr; i++) {
 812                const char *ceil = prefixes->items[i].string;
 813                int len = strlen(ceil);
 814
 815                if (len == 1 && ceil[0] == '/')
 816                        len = 0; /* root matches anything, with length 0 */
 817                else if (!strncmp(path, ceil, len) && path[len] == '/')
 818                        ; /* match of length len */
 819                else
 820                        continue; /* no match */
 821
 822                if (len > max_len)
 823                        max_len = len;
 824        }
 825
 826        return max_len;
 827}
 828
 829/* strip arbitrary amount of directory separators at end of path */
 830static inline int chomp_trailing_dir_sep(const char *path, int len)
 831{
 832        while (len && is_dir_sep(path[len - 1]))
 833                len--;
 834        return len;
 835}
 836
 837/*
 838 * If path ends with suffix (complete path components), returns the
 839 * part before suffix (sans trailing directory separators).
 840 * Otherwise returns NULL.
 841 */
 842char *strip_path_suffix(const char *path, const char *suffix)
 843{
 844        int path_len = strlen(path), suffix_len = strlen(suffix);
 845
 846        while (suffix_len) {
 847                if (!path_len)
 848                        return NULL;
 849
 850                if (is_dir_sep(path[path_len - 1])) {
 851                        if (!is_dir_sep(suffix[suffix_len - 1]))
 852                                return NULL;
 853                        path_len = chomp_trailing_dir_sep(path, path_len);
 854                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 855                }
 856                else if (path[--path_len] != suffix[--suffix_len])
 857                        return NULL;
 858        }
 859
 860        if (path_len && !is_dir_sep(path[path_len - 1]))
 861                return NULL;
 862        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 863}
 864
 865int daemon_avoid_alias(const char *p)
 866{
 867        int sl, ndot;
 868
 869        /*
 870         * This resurrects the belts and suspenders paranoia check by HPA
 871         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 872         * does not do getcwd() based path canonicalization.
 873         *
 874         * sl becomes true immediately after seeing '/' and continues to
 875         * be true as long as dots continue after that without intervening
 876         * non-dot character.
 877         */
 878        if (!p || (*p != '/' && *p != '~'))
 879                return -1;
 880        sl = 1; ndot = 0;
 881        p++;
 882
 883        while (1) {
 884                char ch = *p++;
 885                if (sl) {
 886                        if (ch == '.')
 887                                ndot++;
 888                        else if (ch == '/') {
 889                                if (ndot < 3)
 890                                        /* reject //, /./ and /../ */
 891                                        return -1;
 892                                ndot = 0;
 893                        }
 894                        else if (ch == 0) {
 895                                if (0 < ndot && ndot < 3)
 896                                        /* reject /.$ and /..$ */
 897                                        return -1;
 898                                return 0;
 899                        }
 900                        else
 901                                sl = ndot = 0;
 902                }
 903                else if (ch == 0)
 904                        return 0;
 905                else if (ch == '/') {
 906                        sl = 1;
 907                        ndot = 0;
 908                }
 909        }
 910}
 911
 912static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 913{
 914        if (len < skip)
 915                return 0;
 916        len -= skip;
 917        path += skip;
 918        while (len-- > 0) {
 919                char c = *(path++);
 920                if (c != ' ' && c != '.')
 921                        return 0;
 922        }
 923        return 1;
 924}
 925
 926int is_ntfs_dotgit(const char *name)
 927{
 928        int len;
 929
 930        for (len = 0; ; len++)
 931                if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 932                        if (only_spaces_and_periods(name, len, 4) &&
 933                                        !strncasecmp(name, ".git", 4))
 934                                return 1;
 935                        if (only_spaces_and_periods(name, len, 5) &&
 936                                        !strncasecmp(name, "git~1", 5))
 937                                return 1;
 938                        if (name[len] != '\\')
 939                                return 0;
 940                        name += len + 1;
 941                        len = -1;
 942                }
 943}
 944
 945char *xdg_config_home(const char *filename)
 946{
 947        const char *home, *config_home;
 948
 949        assert(filename);
 950        config_home = getenv("XDG_CONFIG_HOME");
 951        if (config_home && *config_home)
 952                return mkpathdup("%s/git/%s", config_home, filename);
 953
 954        home = getenv("HOME");
 955        if (home)
 956                return mkpathdup("%s/.config/git/%s", home, filename);
 957        return NULL;
 958}
 959
 960GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
 961GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
 962GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
 963GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
 964GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
 965GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
 966GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
 967GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
 968GIT_PATH_FUNC(git_path_shallow, "shallow")