path.con commit Merge branch 'jc/maint-1.6.0-blame-s' into maint (5ab2f7b)
   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
  15static char bad_path[] = "/bad-path/";
  16
  17static char *get_pathname(void)
  18{
  19        static char pathname_array[4][PATH_MAX];
  20        static int index;
  21        return pathname_array[3 & ++index];
  22}
  23
  24static char *cleanup_path(char *path)
  25{
  26        /* Clean it up */
  27        if (!memcmp(path, "./", 2)) {
  28                path += 2;
  29                while (*path == '/')
  30                        path++;
  31        }
  32        return path;
  33}
  34
  35char *mksnpath(char *buf, size_t n, const char *fmt, ...)
  36{
  37        va_list args;
  38        unsigned len;
  39
  40        va_start(args, fmt);
  41        len = vsnprintf(buf, n, fmt, args);
  42        va_end(args);
  43        if (len >= n) {
  44                strlcpy(buf, bad_path, n);
  45                return buf;
  46        }
  47        return cleanup_path(buf);
  48}
  49
  50static char *git_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
  51{
  52        const char *git_dir = get_git_dir();
  53        size_t len;
  54
  55        len = strlen(git_dir);
  56        if (n < len + 1)
  57                goto bad;
  58        memcpy(buf, git_dir, len);
  59        if (len && !is_dir_sep(git_dir[len-1]))
  60                buf[len++] = '/';
  61        len += vsnprintf(buf + len, n - len, fmt, args);
  62        if (len >= n)
  63                goto bad;
  64        return cleanup_path(buf);
  65bad:
  66        strlcpy(buf, bad_path, n);
  67        return buf;
  68}
  69
  70char *git_snpath(char *buf, size_t n, const char *fmt, ...)
  71{
  72        va_list args;
  73        va_start(args, fmt);
  74        (void)git_vsnpath(buf, n, fmt, args);
  75        va_end(args);
  76        return buf;
  77}
  78
  79char *git_pathdup(const char *fmt, ...)
  80{
  81        char path[PATH_MAX];
  82        va_list args;
  83        va_start(args, fmt);
  84        (void)git_vsnpath(path, sizeof(path), fmt, args);
  85        va_end(args);
  86        return xstrdup(path);
  87}
  88
  89char *mkpath(const char *fmt, ...)
  90{
  91        va_list args;
  92        unsigned len;
  93        char *pathname = get_pathname();
  94
  95        va_start(args, fmt);
  96        len = vsnprintf(pathname, PATH_MAX, fmt, args);
  97        va_end(args);
  98        if (len >= PATH_MAX)
  99                return bad_path;
 100        return cleanup_path(pathname);
 101}
 102
 103char *git_path(const char *fmt, ...)
 104{
 105        const char *git_dir = get_git_dir();
 106        char *pathname = get_pathname();
 107        va_list args;
 108        unsigned len;
 109
 110        len = strlen(git_dir);
 111        if (len > PATH_MAX-100)
 112                return bad_path;
 113        memcpy(pathname, git_dir, len);
 114        if (len && git_dir[len-1] != '/')
 115                pathname[len++] = '/';
 116        va_start(args, fmt);
 117        len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
 118        va_end(args);
 119        if (len >= PATH_MAX)
 120                return bad_path;
 121        return cleanup_path(pathname);
 122}
 123
 124
 125/* git_mkstemp() - create tmp file honoring TMPDIR variable */
 126int git_mkstemp(char *path, size_t len, const char *template)
 127{
 128        const char *tmp;
 129        size_t n;
 130
 131        tmp = getenv("TMPDIR");
 132        if (!tmp)
 133                tmp = "/tmp";
 134        n = snprintf(path, len, "%s/%s", tmp, template);
 135        if (len <= n) {
 136                errno = ENAMETOOLONG;
 137                return -1;
 138        }
 139        return mkstemp(path);
 140}
 141
 142
 143int validate_headref(const char *path)
 144{
 145        struct stat st;
 146        char *buf, buffer[256];
 147        unsigned char sha1[20];
 148        int fd;
 149        ssize_t len;
 150
 151        if (lstat(path, &st) < 0)
 152                return -1;
 153
 154        /* Make sure it is a "refs/.." symlink */
 155        if (S_ISLNK(st.st_mode)) {
 156                len = readlink(path, buffer, sizeof(buffer)-1);
 157                if (len >= 5 && !memcmp("refs/", buffer, 5))
 158                        return 0;
 159                return -1;
 160        }
 161
 162        /*
 163         * Anything else, just open it and try to see if it is a symbolic ref.
 164         */
 165        fd = open(path, O_RDONLY);
 166        if (fd < 0)
 167                return -1;
 168        len = read_in_full(fd, buffer, sizeof(buffer)-1);
 169        close(fd);
 170
 171        /*
 172         * Is it a symbolic ref?
 173         */
 174        if (len < 4)
 175                return -1;
 176        if (!memcmp("ref:", buffer, 4)) {
 177                buf = buffer + 4;
 178                len -= 4;
 179                while (len && isspace(*buf))
 180                        buf++, len--;
 181                if (len >= 5 && !memcmp("refs/", buf, 5))
 182                        return 0;
 183        }
 184
 185        /*
 186         * Is this a detached HEAD?
 187         */
 188        if (!get_sha1_hex(buffer, sha1))
 189                return 0;
 190
 191        return -1;
 192}
 193
 194static char *user_path(char *buf, char *path, int sz)
 195{
 196        struct passwd *pw;
 197        char *slash;
 198        int len, baselen;
 199
 200        if (!path || path[0] != '~')
 201                return NULL;
 202        path++;
 203        slash = strchr(path, '/');
 204        if (path[0] == '/' || !path[0]) {
 205                pw = getpwuid(getuid());
 206        }
 207        else {
 208                if (slash) {
 209                        *slash = 0;
 210                        pw = getpwnam(path);
 211                        *slash = '/';
 212                }
 213                else
 214                        pw = getpwnam(path);
 215        }
 216        if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir))
 217                return NULL;
 218        baselen = strlen(pw->pw_dir);
 219        memcpy(buf, pw->pw_dir, baselen);
 220        while ((1 < baselen) && (buf[baselen-1] == '/')) {
 221                buf[baselen-1] = 0;
 222                baselen--;
 223        }
 224        if (slash && slash[1]) {
 225                len = strlen(slash);
 226                if (sz <= baselen + len)
 227                        return NULL;
 228                memcpy(buf + baselen, slash, len + 1);
 229        }
 230        return buf;
 231}
 232
 233/*
 234 * First, one directory to try is determined by the following algorithm.
 235 *
 236 * (0) If "strict" is given, the path is used as given and no DWIM is
 237 *     done. Otherwise:
 238 * (1) "~/path" to mean path under the running user's home directory;
 239 * (2) "~user/path" to mean path under named user's home directory;
 240 * (3) "relative/path" to mean cwd relative directory; or
 241 * (4) "/absolute/path" to mean absolute directory.
 242 *
 243 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 244 * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 245 * what we try.
 246 *
 247 * Second, we try chdir() to that.  Upon failure, we return NULL.
 248 *
 249 * Then, we try if the current directory is a valid git repository.
 250 * Upon failure, we return NULL.
 251 *
 252 * If all goes well, we return the directory we used to chdir() (but
 253 * before ~user is expanded), avoiding getcwd() resolving symbolic
 254 * links.  User relative paths are also returned as they are given,
 255 * except DWIM suffixing.
 256 */
 257char *enter_repo(char *path, int strict)
 258{
 259        static char used_path[PATH_MAX];
 260        static char validated_path[PATH_MAX];
 261
 262        if (!path)
 263                return NULL;
 264
 265        if (!strict) {
 266                static const char *suffix[] = {
 267                        ".git/.git", "/.git", ".git", "", NULL,
 268                };
 269                int len = strlen(path);
 270                int i;
 271                while ((1 < len) && (path[len-1] == '/')) {
 272                        path[len-1] = 0;
 273                        len--;
 274                }
 275                if (PATH_MAX <= len)
 276                        return NULL;
 277                if (path[0] == '~') {
 278                        if (!user_path(used_path, path, PATH_MAX))
 279                                return NULL;
 280                        strcpy(validated_path, path);
 281                        path = used_path;
 282                }
 283                else if (PATH_MAX - 10 < len)
 284                        return NULL;
 285                else {
 286                        path = strcpy(used_path, path);
 287                        strcpy(validated_path, path);
 288                }
 289                len = strlen(path);
 290                for (i = 0; suffix[i]; i++) {
 291                        strcpy(path + len, suffix[i]);
 292                        if (!access(path, F_OK)) {
 293                                strcat(validated_path, suffix[i]);
 294                                break;
 295                        }
 296                }
 297                if (!suffix[i] || chdir(path))
 298                        return NULL;
 299                path = validated_path;
 300        }
 301        else if (chdir(path))
 302                return NULL;
 303
 304        if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 305            validate_headref("HEAD") == 0) {
 306                setenv(GIT_DIR_ENVIRONMENT, ".", 1);
 307                check_repository_format();
 308                return path;
 309        }
 310
 311        return NULL;
 312}
 313
 314int adjust_shared_perm(const char *path)
 315{
 316        struct stat st;
 317        int mode;
 318
 319        if (!shared_repository)
 320                return 0;
 321        if (lstat(path, &st) < 0)
 322                return -1;
 323        mode = st.st_mode;
 324
 325        if (shared_repository) {
 326                int tweak = shared_repository;
 327                if (!(mode & S_IWUSR))
 328                        tweak &= ~0222;
 329                mode |= tweak;
 330        } else {
 331                /* Preserve old PERM_UMASK behaviour */
 332                if (mode & S_IWUSR)
 333                        mode |= S_IWGRP;
 334        }
 335
 336        if (S_ISDIR(mode)) {
 337                mode |= FORCE_DIR_SET_GID;
 338
 339                /* Copy read bits to execute bits */
 340                mode |= (shared_repository & 0444) >> 2;
 341        }
 342
 343        if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
 344                return -2;
 345        return 0;
 346}
 347
 348const char *make_relative_path(const char *abs, const char *base)
 349{
 350        static char buf[PATH_MAX + 1];
 351        int baselen;
 352        if (!base)
 353                return abs;
 354        baselen = strlen(base);
 355        if (prefixcmp(abs, base))
 356                return abs;
 357        if (abs[baselen] == '/')
 358                baselen++;
 359        else if (base[baselen - 1] != '/')
 360                return abs;
 361        strcpy(buf, abs + baselen);
 362        return buf;
 363}
 364
 365/*
 366 * It is okay if dst == src, but they should not overlap otherwise.
 367 *
 368 * Performs the following normalizations on src, storing the result in dst:
 369 * - Ensures that components are separated by '/' (Windows only)
 370 * - Squashes sequences of '/'.
 371 * - Removes "." components.
 372 * - Removes ".." components, and the components the precede them.
 373 * Returns failure (non-zero) if a ".." component appears as first path
 374 * component anytime during the normalization. Otherwise, returns success (0).
 375 *
 376 * Note that this function is purely textual.  It does not follow symlinks,
 377 * verify the existence of the path, or make any system calls.
 378 */
 379int normalize_path_copy(char *dst, const char *src)
 380{
 381        char *dst0;
 382
 383        if (has_dos_drive_prefix(src)) {
 384                *dst++ = *src++;
 385                *dst++ = *src++;
 386        }
 387        dst0 = dst;
 388
 389        if (is_dir_sep(*src)) {
 390                *dst++ = '/';
 391                while (is_dir_sep(*src))
 392                        src++;
 393        }
 394
 395        for (;;) {
 396                char c = *src;
 397
 398                /*
 399                 * A path component that begins with . could be
 400                 * special:
 401                 * (1) "." and ends   -- ignore and terminate.
 402                 * (2) "./"           -- ignore them, eat slash and continue.
 403                 * (3) ".." and ends  -- strip one and terminate.
 404                 * (4) "../"          -- strip one, eat slash and continue.
 405                 */
 406                if (c == '.') {
 407                        if (!src[1]) {
 408                                /* (1) */
 409                                src++;
 410                        } else if (is_dir_sep(src[1])) {
 411                                /* (2) */
 412                                src += 2;
 413                                while (is_dir_sep(*src))
 414                                        src++;
 415                                continue;
 416                        } else if (src[1] == '.') {
 417                                if (!src[2]) {
 418                                        /* (3) */
 419                                        src += 2;
 420                                        goto up_one;
 421                                } else if (is_dir_sep(src[2])) {
 422                                        /* (4) */
 423                                        src += 3;
 424                                        while (is_dir_sep(*src))
 425                                                src++;
 426                                        goto up_one;
 427                                }
 428                        }
 429                }
 430
 431                /* copy up to the next '/', and eat all '/' */
 432                while ((c = *src++) != '\0' && !is_dir_sep(c))
 433                        *dst++ = c;
 434                if (is_dir_sep(c)) {
 435                        *dst++ = '/';
 436                        while (is_dir_sep(c))
 437                                c = *src++;
 438                        src--;
 439                } else if (!c)
 440                        break;
 441                continue;
 442
 443        up_one:
 444                /*
 445                 * dst0..dst is prefix portion, and dst[-1] is '/';
 446                 * go up one level.
 447                 */
 448                dst--;  /* go to trailing '/' */
 449                if (dst <= dst0)
 450                        return -1;
 451                /* Windows: dst[-1] cannot be backslash anymore */
 452                while (dst0 < dst && dst[-1] != '/')
 453                        dst--;
 454        }
 455        *dst = '\0';
 456        return 0;
 457}
 458
 459/*
 460 * path = Canonical absolute path
 461 * prefix_list = Colon-separated list of absolute paths
 462 *
 463 * Determines, for each path in prefix_list, whether the "prefix" really
 464 * is an ancestor directory of path.  Returns the length of the longest
 465 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 466 * is an ancestor.  (Note that this means 0 is returned if prefix_list is
 467 * "/".) "/foo" is not considered an ancestor of "/foobar".  Directories
 468 * are not considered to be their own ancestors.  path must be in a
 469 * canonical form: empty components, or "." or ".." components are not
 470 * allowed.  prefix_list may be null, which is like "".
 471 */
 472int longest_ancestor_length(const char *path, const char *prefix_list)
 473{
 474        char buf[PATH_MAX+1];
 475        const char *ceil, *colon;
 476        int len, max_len = -1;
 477
 478        if (prefix_list == NULL || !strcmp(path, "/"))
 479                return -1;
 480
 481        for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
 482                for (colon = ceil; *colon && *colon != PATH_SEP; colon++);
 483                len = colon - ceil;
 484                if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
 485                        continue;
 486                strlcpy(buf, ceil, len+1);
 487                if (normalize_path_copy(buf, buf) < 0)
 488                        continue;
 489                len = strlen(buf);
 490                if (len > 0 && buf[len-1] == '/')
 491                        buf[--len] = '\0';
 492
 493                if (!strncmp(path, buf, len) &&
 494                    path[len] == '/' &&
 495                    len > max_len) {
 496                        max_len = len;
 497                }
 498        }
 499
 500        return max_len;
 501}
 502
 503/* strip arbitrary amount of directory separators at end of path */
 504static inline int chomp_trailing_dir_sep(const char *path, int len)
 505{
 506        while (len && is_dir_sep(path[len - 1]))
 507                len--;
 508        return len;
 509}
 510
 511/*
 512 * If path ends with suffix (complete path components), returns the
 513 * part before suffix (sans trailing directory separators).
 514 * Otherwise returns NULL.
 515 */
 516char *strip_path_suffix(const char *path, const char *suffix)
 517{
 518        int path_len = strlen(path), suffix_len = strlen(suffix);
 519
 520        while (suffix_len) {
 521                if (!path_len)
 522                        return NULL;
 523
 524                if (is_dir_sep(path[path_len - 1])) {
 525                        if (!is_dir_sep(suffix[suffix_len - 1]))
 526                                return NULL;
 527                        path_len = chomp_trailing_dir_sep(path, path_len);
 528                        suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 529                }
 530                else if (path[--path_len] != suffix[--suffix_len])
 531                        return NULL;
 532        }
 533
 534        if (path_len && !is_dir_sep(path[path_len - 1]))
 535                return NULL;
 536        return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
 537}