Andrew's git / gitweb.git / path.c
?
path.con commit t5550: do not assume the "matching" push is the default (c9704aa)
   1/*
   2 * I'm tired of doing "vsnprintf()" etc just to open a
   3 * file, so here's a "return static buffer with printf"
   4 * interface for paths.
   5 *
   6 * It's obviously not thread-safe. Sue me. But it's quite
   7 * useful for doing things like
   8 *
   9 *   f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
  10 *
  11 * which is what it's designed for.
  12 */
  13#include "cache.h"
  14#include "strbuf.h"
  15#include "string-list.h"
  16
  17static char bad_path[] = "/bad-path/";
  18
  19static char *get_pathname(void)
  20{
  21        static char pathname_array[4][PATH_MAX];
  22        static int index;
  23        return pathname_array[3 & ++index];
  24}
  25
  26static char *cleanup_path(char *path)
  27{
  28        /* Clean it up */
  29        if (!memcmp(path, "./", 2)) {
  30                path += 2;
  31                while (*path == '/')
  32                        path++;
  33        }
  34        return path;
  35}
  36
  37char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  38{
  39        va_list args;
  40        unsigned len;
  41
  42        va_start(args, fmt);
  43        len = vsnprintf(buf, n, fmt, args);
  44        va_end(args);
  45        if (len >= n) {
  46                strlcpy(buf, bad_path, n);
  47                return buf;
  48        }
  49        return cleanup_path(buf);
  50}
  51
  52static char *vsnpath(char *buf, size_t n, const char *fmt, va_list args)
  53{
  54        const char *git_dir = get_git_dir();
  55        size_t len;
  56
  57        len = strlen(git_dir);
  58        if (n < len + 1)
  59                goto bad;
  60        memcpy(buf, git_dir, len);
  61        if (len && !is_dir_sep(git_dir[len-1]))
  62                buf[len++] = '/';
  63        len += vsnprintf(buf + len, n - len, fmt, args);
  64        if (len >= n)
  65                goto bad;
  66        return cleanup_path(buf);
  67bad:
  68        strlcpy(buf, bad_path, n);
  69        return buf;
  70}
  71
  72char *git_snpath(char *buf, size_t n, const char *fmt, ...)
  73{
  74        char *ret;
  75        va_list args;
  76        va_start(args, fmt);
  77        ret = vsnpath(buf, n, fmt, args);
  78        va_end(args);
  79        return ret;
  80}
  81
  82char *git_pathdup(const char *fmt, ...)
  83{
  84        char path[PATH_MAX], *ret;
  85        va_list args;
  86        va_start(args, fmt);
  87        ret = vsnpath(path, sizeof(path), fmt, args);
  88        va_end(args);
  89        return xstrdup(ret);
  90}
  91
  92char *mkpathdup(const char *fmt, ...)
  93{
  94        char *path;
  95        struct strbuf sb = STRBUF_INIT;
  96        va_list args;
  97
  98        va_start(args, fmt);
  99        strbuf_vaddf(&sb, fmt, args);
 100        va_end(args);
 101        path = xstrdup(cleanup_path(sb.buf));
 102
 103        strbuf_release(&sb);
 104        return path;
 105}
 106
 107char *mkpath(const char *fmt, ...)
 108{
 109        va_list args;
 110        unsigned len;
 111        char *pathname = get_pathname();
 112
 113        va_start(args, fmt);
 114        len = vsnprintf(pathname, PATH_MAX, fmt, args);
 115        va_end(args);
 116        if (len >= PATH_MAX)
 117                return bad_path;
 118        return cleanup_path(pathname);
 119}
 120
 121char *git_path(const char *fmt, ...)
 122{
 123        char *pathname = get_pathname();
 124        va_list args;
 125        char *ret;
 126
 127        va_start(args, fmt);
 128        ret = vsnpath(pathname, PATH_MAX, fmt, args);
 129        va_end(args);
 130        return ret;
 131}
 132
 133void home_config_paths(char **global, char **xdg, char *file)
 134{
 135        char *xdg_home = getenv("XDG_CONFIG_HOME");
 136        char *home = getenv("HOME");
 137        char *to_free = NULL;
 138
 139        if (!home) {
 140                if (global)
 141                        *global = NULL;
 142        } else {
 143                if (!xdg_home) {
 144                        to_free = mkpathdup("%s/.config", home);
 145                        xdg_home = to_free;
 146                }
 147                if (global)
 148                        *global = mkpathdup("%s/.gitconfig", home);
 149        }
 150
 151        if (!xdg_home)
 152                *xdg = NULL;
 153        else
 154                *xdg = mkpathdup("%s/git/%s", xdg_home, file);
 155
 156        free(to_free);
 157}
 158
 159char *git_path_submodule(const char *path, const char *fmt, ...)
 160{
 161        char *pathname = get_pathname();
 162        struct strbuf buf = STRBUF_INIT;
 163        const char *git_dir;
 164        va_list args;
 165        unsigned len;
 166
 167        len = strlen(path);
 168        if (len > PATH_MAX-100)
 169                return bad_path;
 170
 171        strbuf_addstr(&buf, path);
 172        if (len && path[len-1] != '/')
 173                strbuf_addch(&buf, '/');
 174        strbuf_addstr(&buf, ".git");
 175
 176        git_dir = read_gitfile(buf.buf);
 177        if (git_dir) {
 178                strbuf_reset(&buf);
 179                strbuf_addstr(&buf, git_dir);
 180        }
 181        strbuf_addch(&buf, '/');
 182
 183        if (buf.len >= PATH_MAX)
 184                return bad_path;
 185        memcpy(pathname, buf.buf, buf.len + 1);
 186
 187        strbuf_release(&buf);
 188        len = strlen(pathname);
 189
 190        va_start(args, fmt);
 191        len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
 192        va_end(args);
 193        if (len >= PATH_MAX)
 194                return bad_path;
 195        return cleanup_path(pathname);
 196}
 197
 198int validate_headref(const char *path)
 199{
 200        struct stat st;
 201        char *buf, buffer[256];
 202        unsigned char sha1[20];
 203        int fd;
 204        ssize_t len;
 205
 206        if (lstat(path, &st) < 0)
 207                return -1;
 208
 209        /* Make sure it is a "refs/.." symlink */
 210        if (S_ISLNK(st.st_mode)) {
 211                len = readlink(path, buffer, sizeof(buffer)-1);
 212                if (len >= 5 && !memcmp("refs/", buffer, 5))
 213                        return 0;
 214                return -1;
 215        }
 216
 217        /*
 218         * Anything else, just open it and try to see if it is a symbolic ref.
 219         */
 220        fd = open(path, O_RDONLY);
 221        if (fd < 0)
 222                return -1;
 223        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 224        close(fd);
 225
 226        /*
 227         * Is it a symbolic ref?
 228         */
 229        if (len < 4)
 230                return -1;
 231        if (!memcmp("ref:", buffer, 4)) {
 232                buf = buffer + 4;
 233                len -= 4;
 234                while (len && isspace(*buf))
 235                        buf++, len--;
 236                if (len >= 5 && !memcmp("refs/", buf, 5))
 237                        return 0;
 238        }
 239
 240        /*
 241         * Is this a detached HEAD?
 242         */
 243        if (!get_sha1_hex(buffer, sha1))
 244                return 0;
 245
 246        return -1;
 247}
 248
 249static struct passwd *getpw_str(const char *username, size_t len)
 250{
 251        struct passwd *pw;
 252        char *username_z = xmalloc(len + 1);
 253        memcpy(username_z, username, len);
 254        username_z[len] = '\0';
 255        pw = getpwnam(username_z);
 256        free(username_z);
 257        return pw;
 258}
 259
 260/*
 261 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 262 * then it is a newly allocated string. Returns NULL on getpw failure or
 263 * if path is NULL.
 264 */
 265char *expand_user_path(const char *path)
 266{
 267        struct strbuf user_path = STRBUF_INIT;
 268        const char *first_slash = strchrnul(path, '/');
 269        const char *to_copy = path;
 270
 271        if (path == NULL)
 272                goto return_null;
 273        if (path[0] == '~') {
 274                const char *username = path + 1;
 275                size_t username_len = first_slash - username;
 276                if (username_len == 0) {
 277                        const char *home = getenv("HOME");
 278                        if (!home)
 279                                goto return_null;
 280                        strbuf_add(&user_path, home, strlen(home));
 281                } else {
 282                        struct passwd *pw = getpw_str(username, username_len);
 283                        if (!pw)
 284                                goto return_null;
 285                        strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
 286                }
 287                to_copy = first_slash;
 288        }
 289        strbuf_add(&user_path, to_copy, strlen(to_copy));
 290        return strbuf_detach(&user_path, NULL);
 291return_null:
 292        strbuf_release(&user_path);
 293        return NULL;
 294}
 295
 296/*
 297 * First, one directory to try is determined by the following algorithm.
 298 *
 299 * (0) If "strict" is given, the path is used as given and no DWIM is
 300 *     done. Otherwise:
 301 * (1) "~/path" to mean path under the running user's home directory;
 302 * (2) "~user/path" to mean path under named user's home directory;
 303 * (3) "relative/path" to mean cwd relative directory; or
 304 * (4) "/absolute/path" to mean absolute directory.
 305 *
 306 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 307 * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 308 * what we try.
 309 *
 310 * Second, we try chdir() to that.  Upon failure, we return NULL.
 311 *
 312 * Then, we try if the current directory is a valid git repository.
 313 * Upon failure, we return NULL.
 314 *
 315 * If all goes well, we return the directory we used to chdir() (but
 316 * before ~user is expanded), avoiding getcwd() resolving symbolic
 317 * links.  User relative paths are also returned as they are given,
 318 * except DWIM suffixing.
 319 */
 320const char *enter_repo(const char *path, int strict)
 321{
 322        static char used_path[PATH_MAX];
 323        static char validated_path[PATH_MAX];
 324
 325        if (!path)
 326                return NULL;
 327
 328        if (!strict) {
 329                static const char *suffix[] = {
 330                        "/.git", "", ".git/.git", ".git", NULL,
 331                };
 332                const char *gitfile;
 333                int len = strlen(path);
 334                int i;
 335                while ((1 < len) && (path[len-1] == '/'))
 336                        len--;
 337
 338                if (PATH_MAX <= len)
 339                        return NULL;
 340                strncpy(used_path, path, len); used_path[len] = 0 ;
 341                strcpy(validated_path, used_path);
 342
 343                if (used_path[0] == '~') {
 344                        char *newpath = expand_user_path(used_path);
 345                        if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
 346                                free(newpath);
 347                                return NULL;
 348                        }
 349                        /*
 350                         * Copy back into the static buffer. A pity
 351                         * since newpath was not bounded, but other
 352                         * branches of the if are limited by PATH_MAX
 353                         * anyway.
 354                         */
 355                        strcpy(used_path, newpath); free(newpath);
 356                }
 357                else if (PATH_MAX - 10 < len)
 358                        return NULL;
 359                len = strlen(used_path);
 360                for (i = 0; suffix[i]; i++) {
 361                        struct stat st;
 362                        strcpy(used_path + len, suffix[i]);
 363                        if (!stat(used_path, &st) &&
 364                            (S_ISREG(st.st_mode) ||
 365                            (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 366                                strcat(validated_path, suffix[i]);
 367                                break;
 368                        }
 369                }
 370                if (!suffix[i])
 371                        return NULL;
 372                gitfile = read_gitfile(used_path) ;
 373                if (gitfile)
 374                        strcpy(used_path, gitfile);
 375                if (chdir(used_path))
 376                        return NULL;
 377                path = validated_path;
 378        }
 379        else if (chdir(path))
 380                return NULL;
 381
 382        if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 383            validate_headref("HEAD") == 0) {
 384                set_git_dir(".");
 385                check_repository_format();
 386                return path;
 387        }
 388
 389        return NULL;
 390}
 391
 392int set_shared_perm(const char *path, int mode)
 393{
 394        struct stat st;
 395        int tweak, shared, orig_mode;
 396
 397        if (!shared_repository) {
 398                if (mode)
 399                        return chmod(path, mode & ~S_IFMT);
 400                return 0;
 401        }
 402        if (!mode) {
 403                if (lstat(path, &st) < 0)
 404                        return -1;
 405                mode = st.st_mode;
 406                orig_mode = mode;
 407        } else
 408                orig_mode = 0;
 409        if (shared_repository < 0)
 410                shared = -shared_repository;
 411        else
 412                shared = shared_repository;
 413        tweak = shared;
 414
 415        if (!(mode & S_IWUSR))
 416                tweak &= ~0222;
 417        if (mode & S_IXUSR)
 418                /* Copy read bits to execute bits */
 419                tweak |= (tweak & 0444) >> 2;
 420        if (shared_repository < 0)
 421                mode = (mode & ~0777) | tweak;
 422        else
 423                mode |= tweak;
 424
 425        if (S_ISDIR(mode)) {
 426                /* Copy read bits to execute bits */
 427                mode |= (shared & 0444) >> 2;
 428                mode |= FORCE_DIR_SET_GID;
 429        }
 430
 431        if (((shared_repository < 0
 432              ? (orig_mode & (FORCE_DIR_SET_GID | 0777))
 433              : (orig_mode & mode)) != mode) &&
 434            chmod(path, (mode & ~S_IFMT)) < 0)
 435                return -2;
 436        return 0;
 437}
 438
 439const char *relative_path(const char *abs, const char *base)
 440{
 441        static char buf[PATH_MAX + 1];
 442        int i = 0, j = 0;
 443
 444        if (!base || !base[0])
 445                return abs;
 446        while (base[i]) {
 447                if (is_dir_sep(base[i])) {
 448                        if (!is_dir_sep(abs[j]))
 449                                return abs;
 450                        while (is_dir_sep(base[i]))
 451                                i++;
 452                        while (is_dir_sep(abs[j]))
 453                                j++;
 454                        continue;
 455                } else if (abs[j] != base[i]) {
 456                        return abs;
 457                }
 458                i++;
 459                j++;
 460        }
 461        if (
 462            /* "/foo" is a prefix of "/foo" */
 463            abs[j] &&
 464            /* "/foo" is not a prefix of "/foobar" */
 465            !is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
 466           )
 467                return abs;
 468        while (is_dir_sep(abs[j]))
 469                j++;
 470        if (!abs[j])
 471                strcpy(buf, ".");
 472        else
 473                strcpy(buf, abs + j);
 474        return buf;
 475}
 476
 477/*
 478 * It is okay if dst == src, but they should not overlap otherwise.
 479 *
 480 * Performs the following normalizations on src, storing the result in dst:
 481 * - Ensures that components are separated by '/' (Windows only)
 482 * - Squashes sequences of '/'.
 483 * - Removes "." components.
 484 * - Removes ".." components, and the components the precede them.
 485 * Returns failure (non-zero) if a ".." component appears as first path
 486 * component anytime during the normalization. Otherwise, returns success (0).
 487 *
 488 * Note that this function is purely textual.  It does not follow symlinks,
 489 * verify the existence of the path, or make any system calls.
 490 */
 491int normalize_path_copy(char *dst, const char *src)
 492{
 493        char *dst0;
 494
 495        if (has_dos_drive_prefix(src)) {
 496                *dst++ = *src++;
 497                *dst++ = *src++;
 498        }
 499        dst0 = dst;
 500
 501        if (is_dir_sep(*src)) {
 502                *dst++ = '/';
 503                while (is_dir_sep(*src))
 504                        src++;
 505        }
 506
 507        for (;;) {
 508                char c = *src;
 509
 510                /*
 511                 * A path component that begins with . could be
 512                 * special:
 513                 * (1) "." and ends   -- ignore and terminate.
 514                 * (2) "./"           -- ignore them, eat slash and continue.
 515                 * (3) ".." and ends  -- strip one and terminate.
 516                 * (4) "../"          -- strip one, eat slash and continue.
 517                 */
 518                if (c == '.') {
 519                        if (!src[1]) {
 520                                /* (1) */
 521                                src++;
 522                        } else if (is_dir_sep(src[1])) {
 523                                /* (2) */
 524                                src += 2;
 525                                while (is_dir_sep(*src))
 526                                        src++;
 527                                continue;
 528                        } else if (src[1] == '.') {
 529                                if (!src[2]) {
 530                                        /* (3) */
 531                                        src += 2;
 532                                        goto up_one;
 533                                } else if (is_dir_sep(src[2])) {
 534                                        /* (4) */
 535                                        src += 3;
 536                                        while (is_dir_sep(*src))
 537                                                src++;
 538                                        goto up_one;
 539                                }
 540                        }
 541                }
 542
 543                /* copy up to the next '/', and eat all '/' */
 544                while ((c = *src++) != '\0' && !is_dir_sep(c))
 545                        *dst++ = c;
 546                if (is_dir_sep(c)) {
 547                        *dst++ = '/';
 548                        while (is_dir_sep(c))
 549                                c = *src++;
 550                        src--;
 551                } else if (!c)
 552                        break;
 553                continue;
 554
 555        up_one:
 556                /*
 557                 * dst0..dst is prefix portion, and dst[-1] is '/';
 558                 * go up one level.
 559                 */
 560                dst--;  /* go to trailing '/' */
 561                if (dst <= dst0)
 562                        return -1;
 563                /* Windows: dst[-1] cannot be backslash anymore */
 564                while (dst0 < dst && dst[-1] != '/')
 565                        dst--;
 566        }
 567        *dst = '\0';
 568        return 0;
 569}
 570
 571/*
 572 * path = Canonical absolute path
 573 * prefixes = string_list containing normalized, absolute paths without
 574 * trailing slashes (except for the root directory, which is denoted by "/").
 575 *
 576 * Determines, for each path in prefixes, whether the "prefix"
 577 * is an ancestor directory of path.  Returns the length of the longest
 578 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 579 * is an ancestor.  (Note that this means 0 is returned if prefixes is
 580 * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
 581 * are not considered to be their own ancestors.  path must be in a
 582 * canonical form: empty components, or "." or ".." components are not
 583 * allowed.
 584 */
 585int longest_ancestor_length(const char *path, struct string_list *prefixes)
 586{
 587        int i, max_len = -1;
 588
 589        if (!strcmp(path, "/"))
 590                return -1;
 591
 592        for (i = 0; i < prefixes->nr; i++) {
 593                const char *ceil = prefixes->items[i].string;
 594                int len = strlen(ceil);
 595
 596                if (len == 1 && ceil[0] == '/')
 597                        len = 0; /* root matches anything, with length 0 */
 598                else if (!strncmp(path, ceil, len) && path[len] == '/')
 599                        ; /* match of length len */
 600                else
 601                        continue; /* no match */
 602
 603                if (len > max_len)
 604                        max_len = len;
 605        }
 606
 607        return max_len;
 608}
 609
 610/* strip arbitrary amount of directory separators at end of path */
 611static inline int chomp_trailing_dir_sep(const char *path, int len)
 612{
 613        while (len && is_dir_sep(path[len - 1]))
 614                len--;
 615        return len;
 616}
 617
 618/*
 619 * If path ends with suffix (complete path components), returns the
 620 * part before suffix (sans trailing directory separators).
 621 * Otherwise returns NULL.
 622 */
 623char *strip_path_suffix(const char *path, const char *suffix)
 624{
 625        int path_len = strlen(path), suffix_len = strlen(suffix);
 626
 627        while (suffix_len) {
 628                if (!path_len)
 629                        return NULL;
 630
 631                if (is_dir_sep(path[path_len - 1])) {
 632                        if (!is_dir_sep(suffix[suffix_len - 1]))
 633                                return NULL;
 634                        path_len = chomp_trailing_dir_sep(path, path_len);
 635                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 636                }
 637                else if (path[--path_len] != suffix[--suffix_len])
 638                        return NULL;
 639        }
 640
 641        if (path_len && !is_dir_sep(path[path_len - 1]))
 642                return NULL;
 643        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 644}
 645
 646int daemon_avoid_alias(const char *p)
 647{
 648        int sl, ndot;
 649
 650        /*
 651         * This resurrects the belts and suspenders paranoia check by HPA
 652         * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
 653         * does not do getcwd() based path canonicalization.
 654         *
 655         * sl becomes true immediately after seeing '/' and continues to
 656         * be true as long as dots continue after that without intervening
 657         * non-dot character.
 658         */
 659        if (!p || (*p != '/' && *p != '~'))
 660                return -1;
 661        sl = 1; ndot = 0;
 662        p++;
 663
 664        while (1) {
 665                char ch = *p++;
 666                if (sl) {
 667                        if (ch == '.')
 668                                ndot++;
 669                        else if (ch == '/') {
 670                                if (ndot < 3)
 671                                        /* reject //, /./ and /../ */
 672                                        return -1;
 673                                ndot = 0;
 674                        }
 675                        else if (ch == 0) {
 676                                if (0 < ndot && ndot < 3)
 677                                        /* reject /.$ and /..$ */
 678                                        return -1;
 679                                return 0;
 680                        }
 681                        else
 682                                sl = ndot = 0;
 683                }
 684                else if (ch == 0)
 685                        return 0;
 686                else if (ch == '/') {
 687                        sl = 1;
 688                        ndot = 0;
 689                }
 690        }
 691}
 692
 693int offset_1st_component(const char *path)
 694{
 695        if (has_dos_drive_prefix(path))
 696                return 2 + is_dir_sep(path[2]);
 697        return is_dir_sep(path[0]);
 698}