diff options
Diffstat (limited to 'path.c')
| -rw-r--r-- | path.c | 459 |
1 files changed, 459 insertions, 0 deletions
@@ -0,0 +1,459 @@ +/* + * I'm tired of doing "vsnprintf()" etc just to open a + * file, so here's a "return static buffer with printf" + * interface for paths. + * + * It's obviously not thread-safe. Sue me. But it's quite + * useful for doing things like + * + * f = open(mkpath("%s/%s.git", base, name), O_RDONLY); + * + * which is what it's designed for. + */ +#include "cache.h" + +static char bad_path[] = "/bad-path/"; + +static char *get_pathname(void) +{ + static char pathname_array[4][PATH_MAX]; + static int index; + return pathname_array[3 & ++index]; +} + +static char *cleanup_path(char *path) +{ + /* Clean it up */ + if (!memcmp(path, "./", 2)) { + path += 2; + while (*path == '/') + path++; + } + return path; +} + +char *mksnpath(char *buf, size_t n, const char *fmt, ...) +{ + va_list args; + unsigned len; + + va_start(args, fmt); + len = vsnprintf(buf, n, fmt, args); + va_end(args); + if (len >= n) { + strlcpy(buf, bad_path, n); + return buf; + } + return cleanup_path(buf); +} + +static char *git_vsnpath(char *buf, size_t n, const char *fmt, va_list args) +{ + const char *git_dir = get_git_dir(); + size_t len; + + len = strlen(git_dir); + if (n < len + 1) + goto bad; + memcpy(buf, git_dir, len); + if (len && !is_dir_sep(git_dir[len-1])) + buf[len++] = '/'; + len += vsnprintf(buf + len, n - len, fmt, args); + if (len >= n) + goto bad; + return cleanup_path(buf); +bad: + strlcpy(buf, bad_path, n); + return buf; +} + +char *git_snpath(char *buf, size_t n, const char *fmt, ...) +{ + va_list args; + va_start(args, fmt); + (void)git_vsnpath(buf, n, fmt, args); + va_end(args); + return buf; +} + +char *git_pathdup(const char *fmt, ...) +{ + char path[PATH_MAX]; + va_list args; + va_start(args, fmt); + (void)git_vsnpath(path, sizeof(path), fmt, args); + va_end(args); + return xstrdup(path); +} + +char *mkpath(const char *fmt, ...) +{ + va_list args; + unsigned len; + char *pathname = get_pathname(); + + va_start(args, fmt); + len = vsnprintf(pathname, PATH_MAX, fmt, args); + va_end(args); + if (len >= PATH_MAX) + return bad_path; + return cleanup_path(pathname); +} + +char *git_path(const char *fmt, ...) +{ + const char *git_dir = get_git_dir(); + char *pathname = get_pathname(); + va_list args; + unsigned len; + + len = strlen(git_dir); + if (len > PATH_MAX-100) + return bad_path; + memcpy(pathname, git_dir, len); + if (len && git_dir[len-1] != '/') + pathname[len++] = '/'; + va_start(args, fmt); + len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args); + va_end(args); + if (len >= PATH_MAX) + return bad_path; + return cleanup_path(pathname); +} + + +/* git_mkstemp() - create tmp file honoring TMPDIR variable */ +int git_mkstemp(char *path, size_t len, const char *template) +{ + const char *tmp; + size_t n; + + tmp = getenv("TMPDIR"); + if (!tmp) + tmp = "/tmp"; + n = snprintf(path, len, "%s/%s", tmp, template); + if (len <= n) { + errno = ENAMETOOLONG; + return -1; + } + return mkstemp(path); +} + + +int validate_headref(const char *path) +{ + struct stat st; + char *buf, buffer[256]; + unsigned char sha1[20]; + int fd; + ssize_t len; + + if (lstat(path, &st) < 0) + return -1; + + /* Make sure it is a "refs/.." symlink */ + if (S_ISLNK(st.st_mode)) { + len = readlink(path, buffer, sizeof(buffer)-1); + if (len >= 5 && !memcmp("refs/", buffer, 5)) + return 0; + return -1; + } + + /* + * Anything else, just open it and try to see if it is a symbolic ref. + */ + fd = open(path, O_RDONLY); + if (fd < 0) + return -1; + len = read_in_full(fd, buffer, sizeof(buffer)-1); + close(fd); + + /* + * Is it a symbolic ref? + */ + if (len < 4) + return -1; + if (!memcmp("ref:", buffer, 4)) { + buf = buffer + 4; + len -= 4; + while (len && isspace(*buf)) + buf++, len--; + if (len >= 5 && !memcmp("refs/", buf, 5)) + return 0; + } + + /* + * Is this a detached HEAD? + */ + if (!get_sha1_hex(buffer, sha1)) + return 0; + + return -1; +} + +static char *user_path(char *buf, char *path, int sz) +{ + struct passwd *pw; + char *slash; + int len, baselen; + + if (!path || path[0] != '~') + return NULL; + path++; + slash = strchr(path, '/'); + if (path[0] == '/' || !path[0]) { + pw = getpwuid(getuid()); + } + else { + if (slash) { + *slash = 0; + pw = getpwnam(path); + *slash = '/'; + } + else + pw = getpwnam(path); + } + if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir)) + return NULL; + baselen = strlen(pw->pw_dir); + memcpy(buf, pw->pw_dir, baselen); + while ((1 < baselen) && (buf[baselen-1] == '/')) { + buf[baselen-1] = 0; + baselen--; + } + if (slash && slash[1]) { + len = strlen(slash); + if (sz <= baselen + len) + return NULL; + memcpy(buf + baselen, slash, len + 1); + } + return buf; +} + +/* + * First, one directory to try is determined by the following algorithm. + * + * (0) If "strict" is given, the path is used as given and no DWIM is + * done. Otherwise: + * (1) "~/path" to mean path under the running user's home directory; + * (2) "~user/path" to mean path under named user's home directory; + * (3) "relative/path" to mean cwd relative directory; or + * (4) "/absolute/path" to mean absolute directory. + * + * Unless "strict" is given, we try access() for existence of "%s.git/.git", + * "%s/.git", "%s.git", "%s" in this order. The first one that exists is + * what we try. + * + * Second, we try chdir() to that. Upon failure, we return NULL. + * + * Then, we try if the current directory is a valid git repository. + * Upon failure, we return NULL. + * + * If all goes well, we return the directory we used to chdir() (but + * before ~user is expanded), avoiding getcwd() resolving symbolic + * links. User relative paths are also returned as they are given, + * except DWIM suffixing. + */ +char *enter_repo(char *path, int strict) +{ + static char used_path[PATH_MAX]; + static char validated_path[PATH_MAX]; + + if (!path) + return NULL; + + if (!strict) { + static const char *suffix[] = { + ".git/.git", "/.git", ".git", "", NULL, + }; + int len = strlen(path); + int i; + while ((1 < len) && (path[len-1] == '/')) { + path[len-1] = 0; + len--; + } + if (PATH_MAX <= len) + return NULL; + if (path[0] == '~') { + if (!user_path(used_path, path, PATH_MAX)) + return NULL; + strcpy(validated_path, path); + path = used_path; + } + else if (PATH_MAX - 10 < len) + return NULL; + else { + path = strcpy(used_path, path); + strcpy(validated_path, path); + } + len = strlen(path); + for (i = 0; suffix[i]; i++) { + strcpy(path + len, suffix[i]); + if (!access(path, F_OK)) { + strcat(validated_path, suffix[i]); + break; + } + } + if (!suffix[i] || chdir(path)) + return NULL; + path = validated_path; + } + else if (chdir(path)) + return NULL; + + if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 && + validate_headref("HEAD") == 0) { + setenv(GIT_DIR_ENVIRONMENT, ".", 1); + check_repository_format(); + return path; + } + + return NULL; +} + +int adjust_shared_perm(const char *path) +{ + struct stat st; + int mode; + + if (!shared_repository) + return 0; + if (lstat(path, &st) < 0) + return -1; + mode = st.st_mode; + + if (shared_repository) { + int tweak = shared_repository; + if (!(mode & S_IWUSR)) + tweak &= ~0222; + mode |= tweak; + } else { + /* Preserve old PERM_UMASK behaviour */ + if (mode & S_IWUSR) + mode |= S_IWGRP; + } + + if (S_ISDIR(mode)) { + mode |= FORCE_DIR_SET_GID; + + /* Copy read bits to execute bits */ + mode |= (shared_repository & 0444) >> 2; + } + + if ((mode & st.st_mode) != mode && chmod(path, mode) < 0) + return -2; + return 0; +} + +const char *make_relative_path(const char *abs, const char *base) +{ + static char buf[PATH_MAX + 1]; + int baselen; + if (!base) + return abs; + baselen = strlen(base); + if (prefixcmp(abs, base)) + return abs; + if (abs[baselen] == '/') + baselen++; + else if (base[baselen - 1] != '/') + return abs; + strcpy(buf, abs + baselen); + return buf; +} + +/* + * path = absolute path + * buf = buffer of at least max(2, strlen(path)+1) bytes + * It is okay if buf == path, but they should not overlap otherwise. + * + * Performs the following normalizations on path, storing the result in buf: + * - Removes trailing slashes. + * - Removes empty components. + * - Removes "." components. + * - Removes ".." components, and the components the precede them. + * "" and paths that contain only slashes are normalized to "/". + * Returns the length of the output. + * + * Note that this function is purely textual. It does not follow symlinks, + * verify the existence of the path, or make any system calls. + */ +int normalize_absolute_path(char *buf, const char *path) +{ + const char *comp_start = path, *comp_end = path; + char *dst = buf; + int comp_len; + assert(buf); + assert(path); + + while (*comp_start) { + assert(*comp_start == '/'); + while (*++comp_end && *comp_end != '/') + ; /* nothing */ + comp_len = comp_end - comp_start; + + if (!strncmp("/", comp_start, comp_len) || + !strncmp("/.", comp_start, comp_len)) + goto next; + + if (!strncmp("/..", comp_start, comp_len)) { + while (dst > buf && *--dst != '/') + ; /* nothing */ + goto next; + } + + memmove(dst, comp_start, comp_len); + dst += comp_len; + next: + comp_start = comp_end; + } + + if (dst == buf) + *dst++ = '/'; + + *dst = '\0'; + return dst - buf; +} + +/* + * path = Canonical absolute path + * prefix_list = Colon-separated list of absolute paths + * + * Determines, for each path in prefix_list, whether the "prefix" really + * is an ancestor directory of path. Returns the length of the longest + * ancestor directory, excluding any trailing slashes, or -1 if no prefix + * is an ancestor. (Note that this means 0 is returned if prefix_list is + * "/".) "/foo" is not considered an ancestor of "/foobar". Directories + * are not considered to be their own ancestors. path must be in a + * canonical form: empty components, or "." or ".." components are not + * allowed. prefix_list may be null, which is like "". + */ +int longest_ancestor_length(const char *path, const char *prefix_list) +{ + char buf[PATH_MAX+1]; + const char *ceil, *colon; + int len, max_len = -1; + + if (prefix_list == NULL || !strcmp(path, "/")) + return -1; + + for (colon = ceil = prefix_list; *colon; ceil = colon+1) { + for (colon = ceil; *colon && *colon != ':'; colon++); + len = colon - ceil; + if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil)) + continue; + strlcpy(buf, ceil, len+1); + len = normalize_absolute_path(buf, buf); + /* Strip "trailing slashes" from "/". */ + if (len == 1) + len = 0; + + if (!strncmp(path, buf, len) && + path[len] == '/' && + len > max_len) { + max_len = len; + } + } + + return max_len; +} |