path.con commit http-push: use an argv_array for setup_revisions (a0355f6)
   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
 178char *git_path_buf(struct strbuf *buf, const char *fmt, ...)
 179{
 180        va_list args;
 181        strbuf_reset(buf);
 182        va_start(args, fmt);
 183        do_git_path(buf, fmt, args);
 184        va_end(args);
 185        return buf->buf;
 186}
 187
 188void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 189{
 190        va_list args;
 191        va_start(args, fmt);
 192        do_git_path(sb, fmt, args);
 193        va_end(args);
 194}
 195
 196const char *git_path(const char *fmt, ...)
 197{
 198        struct strbuf *pathname = get_pathname();
 199        va_list args;
 200        va_start(args, fmt);
 201        do_git_path(pathname, fmt, args);
 202        va_end(args);
 203        return pathname->buf;
 204}
 205
 206char *git_pathdup(const char *fmt, ...)
 207{
 208        struct strbuf path = STRBUF_INIT;
 209        va_list args;
 210        va_start(args, fmt);
 211        do_git_path(&path, fmt, args);
 212        va_end(args);
 213        return strbuf_detach(&path, NULL);
 214}
 215
 216char *mkpathdup(const char *fmt, ...)
 217{
 218        struct strbuf sb = STRBUF_INIT;
 219        va_list args;
 220        va_start(args, fmt);
 221        strbuf_vaddf(&sb, fmt, args);
 222        va_end(args);
 223        strbuf_cleanup_path(&sb);
 224        return strbuf_detach(&sb, NULL);
 225}
 226
 227const char *mkpath(const char *fmt, ...)
 228{
 229        va_list args;
 230        struct strbuf *pathname = get_pathname();
 231        va_start(args, fmt);
 232        strbuf_vaddf(pathname, fmt, args);
 233        va_end(args);
 234        return cleanup_path(pathname->buf);
 235}
 236
 237static void do_submodule_path(struct strbuf *buf, const char *path,
 238                              const char *fmt, va_list args)
 239{
 240        const char *git_dir;
 241
 242        strbuf_addstr(buf, path);
 243        if (buf->len && buf->buf[buf->len - 1] != '/')
 244                strbuf_addch(buf, '/');
 245        strbuf_addstr(buf, ".git");
 246
 247        git_dir = read_gitfile(buf->buf);
 248        if (git_dir) {
 249                strbuf_reset(buf);
 250                strbuf_addstr(buf, git_dir);
 251        }
 252        strbuf_addch(buf, '/');
 253
 254        strbuf_vaddf(buf, fmt, args);
 255        strbuf_cleanup_path(buf);
 256}
 257
 258char *git_pathdup_submodule(const char *path, const char *fmt, ...)
 259{
 260        va_list args;
 261        struct strbuf buf = STRBUF_INIT;
 262        va_start(args, fmt);
 263        do_submodule_path(&buf, path, fmt, args);
 264        va_end(args);
 265        return strbuf_detach(&buf, NULL);
 266}
 267
 268void strbuf_git_path_submodule(struct strbuf *buf, const char *path,
 269                               const char *fmt, ...)
 270{
 271        va_list args;
 272        va_start(args, fmt);
 273        do_submodule_path(buf, path, fmt, args);
 274        va_end(args);
 275}
 276
 277int validate_headref(const char *path)
 278{
 279        struct stat st;
 280        char *buf, buffer[256];
 281        unsigned char sha1[20];
 282        int fd;
 283        ssize_t len;
 284
 285        if (lstat(path, &st) < 0)
 286                return -1;
 287
 288        /* Make sure it is a "refs/.." symlink */
 289        if (S_ISLNK(st.st_mode)) {
 290                len = readlink(path, buffer, sizeof(buffer)-1);
 291                if (len >= 5 && !memcmp("refs/", buffer, 5))
 292                        return 0;
 293                return -1;
 294        }
 295
 296        /*
 297         * Anything else, just open it and try to see if it is a symbolic ref.
 298         */
 299        fd = open(path, O_RDONLY);
 300        if (fd < 0)
 301                return -1;
 302        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 303        close(fd);
 304
 305        /*
 306         * Is it a symbolic ref?
 307         */
 308        if (len < 4)
 309                return -1;
 310        if (!memcmp("ref:", buffer, 4)) {
 311                buf = buffer + 4;
 312                len -= 4;
 313                while (len && isspace(*buf))
 314                        buf++, len--;
 315                if (len >= 5 && !memcmp("refs/", buf, 5))
 316                        return 0;
 317        }
 318
 319        /*
 320         * Is this a detached HEAD?
 321         */
 322        if (!get_sha1_hex(buffer, sha1))
 323                return 0;
 324
 325        return -1;
 326}
 327
 328static struct passwd *getpw_str(const char *username, size_t len)
 329{
 330        struct passwd *pw;
 331        char *username_z = xmemdupz(username, len);
 332        pw = getpwnam(username_z);
 333        free(username_z);
 334        return pw;
 335}
 336
 337/*
 338 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 339 * then it is a newly allocated string. Returns NULL on getpw failure or
 340 * if path is NULL.
 341 */
 342char *expand_user_path(const char *path)
 343{
 344        struct strbuf user_path = STRBUF_INIT;
 345        const char *to_copy = path;
 346
 347        if (path == NULL)
 348                goto return_null;
 349        if (path[0] == '~') {
 350                const char *first_slash = strchrnul(path, '/');
 351                const char *username = path + 1;
 352                size_t username_len = first_slash - username;
 353                if (username_len == 0) {
 354                        const char *home = getenv("HOME");
 355                        if (!home)
 356                                goto return_null;
 357                        strbuf_addstr(&user_path, home);
 358                } else {
 359                        struct passwd *pw = getpw_str(username, username_len);
 360                        if (!pw)
 361                                goto return_null;
 362                        strbuf_addstr(&user_path, pw->pw_dir);
 363                }
 364                to_copy = first_slash;
 365        }
 366        strbuf_addstr(&user_path, to_copy);
 367        return strbuf_detach(&user_path, NULL);
 368return_null:
 369        strbuf_release(&user_path);
 370        return NULL;
 371}
 372
 373/*
 374 * First, one directory to try is determined by the following algorithm.
 375 *
 376 * (0) If "strict" is given, the path is used as given and no DWIM is
 377 *     done. Otherwise:
 378 * (1) "~/path" to mean path under the running user's home directory;
 379 * (2) "~user/path" to mean path under named user's home directory;
 380 * (3) "relative/path" to mean cwd relative directory; or
 381 * (4) "/absolute/path" to mean absolute directory.
 382 *
 383 * Unless "strict" is given, we check "%s/.git", "%s", "%s.git/.git", "%s.git"
 384 * in this order. We select the first one that is a valid git repository, and
 385 * chdir() to it. If none match, or we fail to chdir, we return NULL.
 386 *
 387 * If all goes well, we return the directory we used to chdir() (but
 388 * before ~user is expanded), avoiding getcwd() resolving symbolic
 389 * links.  User relative paths are also returned as they are given,
 390 * except DWIM suffixing.
 391 */
 392const char *enter_repo(const char *path, int strict)
 393{
 394        static struct strbuf validated_path = STRBUF_INIT;
 395        static struct strbuf used_path = STRBUF_INIT;
 396
 397        if (!path)
 398                return NULL;
 399
 400        if (!strict) {
 401                static const char *suffix[] = {
 402                        "/.git", "", ".git/.git", ".git", NULL,
 403                };
 404                const char *gitfile;
 405                int len = strlen(path);
 406                int i;
 407                while ((1 < len) && (path[len-1] == '/'))
 408                        len--;
 409
 410                /*
 411                 * We can handle arbitrary-sized buffers, but this remains as a
 412                 * sanity check on untrusted input.
 413                 */
 414                if (PATH_MAX <= len)
 415                        return NULL;
 416
 417                strbuf_reset(&used_path);
 418                strbuf_reset(&validated_path);
 419                strbuf_add(&used_path, path, len);
 420                strbuf_add(&validated_path, path, len);
 421
 422                if (used_path.buf[0] == '~') {
 423                        char *newpath = expand_user_path(used_path.buf);
 424                        if (!newpath)
 425                                return NULL;
 426                        strbuf_attach(&used_path, newpath, strlen(newpath),
 427                                      strlen(newpath));
 428                }
 429                for (i = 0; suffix[i]; i++) {
 430                        struct stat st;
 431                        size_t baselen = used_path.len;
 432                        strbuf_addstr(&used_path, suffix[i]);
 433                        if (!stat(used_path.buf, &st) &&
 434                            (S_ISREG(st.st_mode) ||
 435                            (S_ISDIR(st.st_mode) && is_git_directory(used_path.buf)))) {
 436                                strbuf_addstr(&validated_path, suffix[i]);
 437                                break;
 438                        }
 439                        strbuf_setlen(&used_path, baselen);
 440                }
 441                if (!suffix[i])
 442                        return NULL;
 443                gitfile = read_gitfile(used_path.buf) ;
 444                if (gitfile) {
 445                        strbuf_reset(&used_path);
 446                        strbuf_addstr(&used_path, gitfile);
 447                }
 448                if (chdir(used_path.buf))
 449                        return NULL;
 450                path = validated_path.buf;
 451        }
 452        else if (chdir(path))
 453                return NULL;
 454
 455        if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 456            validate_headref("HEAD") == 0) {
 457                set_git_dir(".");
 458                check_repository_format();
 459                return path;
 460        }
 461
 462        return NULL;
 463}
 464
 465static int calc_shared_perm(int mode)
 466{
 467        int tweak;
 468
 469        if (shared_repository < 0)
 470                tweak = -shared_repository;
 471        else
 472                tweak = shared_repository;
 473
 474        if (!(mode & S_IWUSR))
 475                tweak &= ~0222;
 476        if (mode & S_IXUSR)
 477                /* Copy read bits to execute bits */
 478                tweak |= (tweak & 0444) >> 2;
 479        if (shared_repository < 0)
 480                mode = (mode & ~0777) | tweak;
 481        else
 482                mode |= tweak;
 483
 484        return mode;
 485}
 486
 487
 488int adjust_shared_perm(const char *path)
 489{
 490        int old_mode, new_mode;
 491
 492        if (!shared_repository)
 493                return 0;
 494        if (get_st_mode_bits(path, &old_mode) < 0)
 495                return -1;
 496
 497        new_mode = calc_shared_perm(old_mode);
 498        if (S_ISDIR(old_mode)) {
 499                /* Copy read bits to execute bits */
 500                new_mode |= (new_mode & 0444) >> 2;
 501                new_mode |= FORCE_DIR_SET_GID;
 502        }
 503
 504        if (((old_mode ^ new_mode) & ~S_IFMT) &&
 505                        chmod(path, (new_mode & ~S_IFMT)) < 0)
 506                return -2;
 507        return 0;
 508}
 509
 510static int have_same_root(const char *path1, const char *path2)
 511{
 512        int is_abs1, is_abs2;
 513
 514        is_abs1 = is_absolute_path(path1);
 515        is_abs2 = is_absolute_path(path2);
 516        return (is_abs1 && is_abs2 && tolower(path1[0]) == tolower(path2[0])) ||
 517               (!is_abs1 && !is_abs2);
 518}
 519
 520/*
 521 * Give path as relative to prefix.
 522 *
 523 * The strbuf may or may not be used, so do not assume it contains the
 524 * returned path.
 525 */
 526const char *relative_path(const char *in, const char *prefix,
 527                          struct strbuf *sb)
 528{
 529        int in_len = in ? strlen(in) : 0;
 530        int prefix_len = prefix ? strlen(prefix) : 0;
 531        int in_off = 0;
 532        int prefix_off = 0;
 533        int i = 0, j = 0;
 534
 535        if (!in_len)
 536                return "./";
 537        else if (!prefix_len)
 538                return in;
 539
 540        if (have_same_root(in, prefix)) {
 541                /* bypass dos_drive, for "c:" is identical to "C:" */
 542                if (has_dos_drive_prefix(in)) {
 543                        i = 2;
 544                        j = 2;
 545                }
 546        } else {
 547                return in;
 548        }
 549
 550        while (i < prefix_len && j < in_len && prefix[i] == in[j]) {
 551                if (is_dir_sep(prefix[i])) {
 552                        while (is_dir_sep(prefix[i]))
 553                                i++;
 554                        while (is_dir_sep(in[j]))
 555                                j++;
 556                        prefix_off = i;
 557                        in_off = j;
 558                } else {
 559                        i++;
 560                        j++;
 561                }
 562        }
 563
 564        if (
 565            /* "prefix" seems like prefix of "in" */
 566            i >= prefix_len &&
 567            /*
 568             * but "/foo" is not a prefix of "/foobar"
 569             * (i.e. prefix not end with '/')
 570             */
 571            prefix_off < prefix_len) {
 572                if (j >= in_len) {
 573                        /* in="/a/b", prefix="/a/b" */
 574                        in_off = in_len;
 575                } else if (is_dir_sep(in[j])) {
 576                        /* in="/a/b/c", prefix="/a/b" */
 577                        while (is_dir_sep(in[j]))
 578                                j++;
 579                        in_off = j;
 580                } else {
 581                        /* in="/a/bbb/c", prefix="/a/b" */
 582                        i = prefix_off;
 583                }
 584        } else if (
 585                   /* "in" is short than "prefix" */
 586                   j >= in_len &&
 587                   /* "in" not end with '/' */
 588                   in_off < in_len) {
 589                if (is_dir_sep(prefix[i])) {
 590                        /* in="/a/b", prefix="/a/b/c/" */
 591                        while (is_dir_sep(prefix[i]))
 592                                i++;
 593                        in_off = in_len;
 594                }
 595        }
 596        in += in_off;
 597        in_len -= in_off;
 598
 599        if (i >= prefix_len) {
 600                if (!in_len)
 601                        return "./";
 602                else
 603                        return in;
 604        }
 605
 606        strbuf_reset(sb);
 607        strbuf_grow(sb, in_len);
 608
 609        while (i < prefix_len) {
 610                if (is_dir_sep(prefix[i])) {
 611                        strbuf_addstr(sb, "../");
 612                        while (is_dir_sep(prefix[i]))
 613                                i++;
 614                        continue;
 615                }
 616                i++;
 617        }
 618        if (!is_dir_sep(prefix[prefix_len - 1]))
 619                strbuf_addstr(sb, "../");
 620
 621        strbuf_addstr(sb, in);
 622
 623        return sb->buf;
 624}
 625
 626/*
 627 * A simpler implementation of relative_path
 628 *
 629 * Get relative path by removing "prefix" from "in". This function
 630 * first appears in v1.5.6-1-g044bbbc, and makes git_dir shorter
 631 * to increase performance when traversing the path to work_tree.
 632 */
 633const char *remove_leading_path(const char *in, const char *prefix)
 634{
 635        static struct strbuf buf = STRBUF_INIT;
 636        int i = 0, j = 0;
 637
 638        if (!prefix || !prefix[0])
 639                return in;
 640        while (prefix[i]) {
 641                if (is_dir_sep(prefix[i])) {
 642                        if (!is_dir_sep(in[j]))
 643                                return in;
 644                        while (is_dir_sep(prefix[i]))
 645                                i++;
 646                        while (is_dir_sep(in[j]))
 647                                j++;
 648                        continue;
 649                } else if (in[j] != prefix[i]) {
 650                        return in;
 651                }
 652                i++;
 653                j++;
 654        }
 655        if (
 656            /* "/foo" is a prefix of "/foo" */
 657            in[j] &&
 658            /* "/foo" is not a prefix of "/foobar" */
 659            !is_dir_sep(prefix[i-1]) && !is_dir_sep(in[j])
 660           )
 661                return in;
 662        while (is_dir_sep(in[j]))
 663                j++;
 664
 665        strbuf_reset(&buf);
 666        if (!in[j])
 667                strbuf_addstr(&buf, ".");
 668        else
 669                strbuf_addstr(&buf, in + j);
 670        return buf.buf;
 671}
 672
 673/*
 674 * It is okay if dst == src, but they should not overlap otherwise.
 675 *
 676 * Performs the following normalizations on src, storing the result in dst:
 677 * - Ensures that components are separated by '/' (Windows only)
 678 * - Squashes sequences of '/'.
 679 * - Removes "." components.
 680 * - Removes ".." components, and the components the precede them.
 681 * Returns failure (non-zero) if a ".." component appears as first path
 682 * component anytime during the normalization. Otherwise, returns success (0).
 683 *
 684 * Note that this function is purely textual.  It does not follow symlinks,
 685 * verify the existence of the path, or make any system calls.
 686 *
 687 * prefix_len != NULL is for a specific case of prefix_pathspec():
 688 * assume that src == dst and src[0..prefix_len-1] is already
 689 * normalized, any time "../" eats up to the prefix_len part,
 690 * prefix_len is reduced. In the end prefix_len is the remaining
 691 * prefix that has not been overridden by user pathspec.
 692 */
 693int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 694{
 695        char *dst0;
 696
 697        if (has_dos_drive_prefix(src)) {
 698                *dst++ = *src++;
 699                *dst++ = *src++;
 700        }
 701        dst0 = dst;
 702
 703        if (is_dir_sep(*src)) {
 704                *dst++ = '/';
 705                while (is_dir_sep(*src))
 706                        src++;
 707        }
 708
 709        for (;;) {
 710                char c = *src;
 711
 712                /*
 713                 * A path component that begins with . could be
 714                 * special:
 715                 * (1) "." and ends   -- ignore and terminate.
 716                 * (2) "./"           -- ignore them, eat slash and continue.
 717                 * (3) ".." and ends  -- strip one and terminate.
 718                 * (4) "../"          -- strip one, eat slash and continue.
 719                 */
 720                if (c == '.') {
 721                        if (!src[1]) {
 722                                /* (1) */
 723                                src++;
 724                        } else if (is_dir_sep(src[1])) {
 725                                /* (2) */
 726                                src += 2;
 727                                while (is_dir_sep(*src))
 728                                        src++;
 729                                continue;
 730                        } else if (src[1] == '.') {
 731                                if (!src[2]) {
 732                                        /* (3) */
 733                                        src += 2;
 734                                        goto up_one;
 735                                } else if (is_dir_sep(src[2])) {
 736                                        /* (4) */
 737                                        src += 3;
 738                                        while (is_dir_sep(*src))
 739                                                src++;
 740                                        goto up_one;
 741                                }
 742                        }
 743                }
 744
 745                /* copy up to the next '/', and eat all '/' */
 746                while ((c = *src++) != '\0' && !is_dir_sep(c))
 747                        *dst++ = c;
 748                if (is_dir_sep(c)) {
 749                        *dst++ = '/';
 750                        while (is_dir_sep(c))
 751                                c = *src++;
 752                        src--;
 753                } else if (!c)
 754                        break;
 755                continue;
 756
 757        up_one:
 758                /*
 759                 * dst0..dst is prefix portion, and dst[-1] is '/';
 760                 * go up one level.
 761                 */
 762                dst--;  /* go to trailing '/' */
 763                if (dst <= dst0)
 764                        return -1;
 765                /* Windows: dst[-1] cannot be backslash anymore */
 766                while (dst0 < dst && dst[-1] != '/')
 767                        dst--;
 768                if (prefix_len && *prefix_len > dst - dst0)
 769                        *prefix_len = dst - dst0;
 770        }
 771        *dst = '\0';
 772        return 0;
 773}
 774
 775int normalize_path_copy(char *dst, const char *src)
 776{
 777        return normalize_path_copy_len(dst, src, NULL);
 778}
 779
 780/*
 781 * path = Canonical absolute path
 782 * prefixes = string_list containing normalized, absolute paths without
 783 * trailing slashes (except for the root directory, which is denoted by "/").
 784 *
 785 * Determines, for each path in prefixes, whether the "prefix"
 786 * is an ancestor directory of path.  Returns the length of the longest
 787 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 788 * is an ancestor.  (Note that this means 0 is returned if prefixes is
 789 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 790 * are not considered to be their own ancestors.  path must be in a
 791 * canonical form: empty components, or "." or ".." components are not
 792 * allowed.
 793 */
 794int longest_ancestor_length(const char *path, struct string_list *prefixes)
 795{
 796        int i, max_len = -1;
 797
 798        if (!strcmp(path, "/"))
 799                return -1;
 800
 801        for (i = 0; i < prefixes->nr; i++) {
 802                const char *ceil = prefixes->items[i].string;
 803                int len = strlen(ceil);
 804
 805                if (len == 1 && ceil[0] == '/')
 806                        len = 0; /* root matches anything, with length 0 */
 807                else if (!strncmp(path, ceil, len) && path[len] == '/')
 808                        ; /* match of length len */
 809                else
 810                        continue; /* no match */
 811
 812                if (len > max_len)
 813                        max_len = len;
 814        }
 815
 816        return max_len;
 817}
 818
 819/* strip arbitrary amount of directory separators at end of path */
 820static inline int chomp_trailing_dir_sep(const char *path, int len)
 821{
 822        while (len && is_dir_sep(path[len - 1]))
 823                len--;
 824        return len;
 825}
 826
 827/*
 828 * If path ends with suffix (complete path components), returns the
 829 * part before suffix (sans trailing directory separators).
 830 * Otherwise returns NULL.
 831 */
 832char *strip_path_suffix(const char *path, const char *suffix)
 833{
 834        int path_len = strlen(path), suffix_len = strlen(suffix);
 835
 836        while (suffix_len) {
 837                if (!path_len)
 838                        return NULL;
 839
 840                if (is_dir_sep(path[path_len - 1])) {
 841                        if (!is_dir_sep(suffix[suffix_len - 1]))
 842                                return NULL;
 843                        path_len = chomp_trailing_dir_sep(path, path_len);
 844                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 845                }
 846                else if (path[--path_len] != suffix[--suffix_len])
 847                        return NULL;
 848        }
 849
 850        if (path_len && !is_dir_sep(path[path_len - 1]))
 851                return NULL;
 852        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 853}
 854
 855int daemon_avoid_alias(const char *p)
 856{
 857        int sl, ndot;
 858
 859        /*
 860         * This resurrects the belts and suspenders paranoia check by HPA
 861         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 862         * does not do getcwd() based path canonicalization.
 863         *
 864         * sl becomes true immediately after seeing '/' and continues to
 865         * be true as long as dots continue after that without intervening
 866         * non-dot character.
 867         */
 868        if (!p || (*p != '/' && *p != '~'))
 869                return -1;
 870        sl = 1; ndot = 0;
 871        p++;
 872
 873        while (1) {
 874                char ch = *p++;
 875                if (sl) {
 876                        if (ch == '.')
 877                                ndot++;
 878                        else if (ch == '/') {
 879                                if (ndot < 3)
 880                                        /* reject //, /./ and /../ */
 881                                        return -1;
 882                                ndot = 0;
 883                        }
 884                        else if (ch == 0) {
 885                                if (0 < ndot && ndot < 3)
 886                                        /* reject /.$ and /..$ */
 887                                        return -1;
 888                                return 0;
 889                        }
 890                        else
 891                                sl = ndot = 0;
 892                }
 893                else if (ch == 0)
 894                        return 0;
 895                else if (ch == '/') {
 896                        sl = 1;
 897                        ndot = 0;
 898                }
 899        }
 900}
 901
 902static int only_spaces_and_periods(const char *path, size_t len, size_t skip)
 903{
 904        if (len < skip)
 905                return 0;
 906        len -= skip;
 907        path += skip;
 908        while (len-- > 0) {
 909                char c = *(path++);
 910                if (c != ' ' && c != '.')
 911                        return 0;
 912        }
 913        return 1;
 914}
 915
 916int is_ntfs_dotgit(const char *name)
 917{
 918        int len;
 919
 920        for (len = 0; ; len++)
 921                if (!name[len] || name[len] == '\\' || is_dir_sep(name[len])) {
 922                        if (only_spaces_and_periods(name, len, 4) &&
 923                                        !strncasecmp(name, ".git", 4))
 924                                return 1;
 925                        if (only_spaces_and_periods(name, len, 5) &&
 926                                        !strncasecmp(name, "git~1", 5))
 927                                return 1;
 928                        if (name[len] != '\\')
 929                                return 0;
 930                        name += len + 1;
 931                        len = -1;
 932                }
 933}
 934
 935char *xdg_config_home(const char *filename)
 936{
 937        const char *home, *config_home;
 938
 939        assert(filename);
 940        config_home = getenv("XDG_CONFIG_HOME");
 941        if (config_home && *config_home)
 942                return mkpathdup("%s/git/%s", config_home, filename);
 943
 944        home = getenv("HOME");
 945        if (home)
 946                return mkpathdup("%s/.config/git/%s", home, filename);
 947        return NULL;
 948}
 949
 950GIT_PATH_FUNC(git_path_cherry_pick_head, "CHERRY_PICK_HEAD")
 951GIT_PATH_FUNC(git_path_revert_head, "REVERT_HEAD")
 952GIT_PATH_FUNC(git_path_squash_msg, "SQUASH_MSG")
 953GIT_PATH_FUNC(git_path_merge_msg, "MERGE_MSG")
 954GIT_PATH_FUNC(git_path_merge_rr, "MERGE_RR")
 955GIT_PATH_FUNC(git_path_merge_mode, "MERGE_MODE")
 956GIT_PATH_FUNC(git_path_merge_head, "MERGE_HEAD")
 957GIT_PATH_FUNC(git_path_fetch_head, "FETCH_HEAD")
 958GIT_PATH_FUNC(git_path_shallow, "shallow")