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index c1d567996d225c03f58c1208f4806f74f64e92e1..504eae061fe27e846f67f3e1c25d51e886420b62 100644 (file)
--- a/path.c
+++ b/path.c
return buf;
}
-/* We allow "recursive" symbolic links. Only within reason, though. */
-#define MAXDEPTH 5
-
const char *make_relative_path(const char *abs, const char *base)
{
static char buf[PATH_MAX + 1];
return buf;
}
-const char *make_absolute_path(const char *path)
+/*
+ * 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)
{
- static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
- char cwd[1024] = "";
- int buf_index = 1, len;
+ 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;
+ }
- int depth = MAXDEPTH;
- char *last_elem = NULL;
- struct stat st;
+ memcpy(dst, comp_start, comp_len);
+ dst += comp_len;
+ next:
+ comp_start = comp_end;
+ }
- if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
- die ("Too long path: %.*s", 60, path);
-
- while (depth--) {
- if (stat(buf, &st) || !S_ISDIR(st.st_mode)) {
- char *last_slash = strrchr(buf, '/');
- if (last_slash) {
- *last_slash = '\0';
- last_elem = xstrdup(last_slash + 1);
- } else {
- last_elem = xstrdup(buf);
- *buf = '\0';
- }
- }
+ if (dst == buf)
+ *dst++ = '/';
+
+ *dst = '\0';
+ return dst - buf;
+}
- if (*buf) {
- if (!*cwd && !getcwd(cwd, sizeof(cwd)))
- die ("Could not get current working directory");
+/*
+ * path = Canonical absolute path
+ * prefix_list = Colon-separated list of absolute paths
+ *
+ * Determines, for each path in parent_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 (chdir(buf))
- die ("Could not switch to '%s'", buf);
- }
- if (!getcwd(buf, PATH_MAX))
- die ("Could not get current working directory");
-
- if (last_elem) {
- int len = strlen(buf);
- if (len + strlen(last_elem) + 2 > PATH_MAX)
- die ("Too long path name: '%s/%s'",
- buf, last_elem);
- buf[len] = '/';
- strcpy(buf + len + 1, last_elem);
- free(last_elem);
- last_elem = NULL;
- }
+ if (prefix_list == NULL || !strcmp(path, "/"))
+ return -1;
- if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
- len = readlink(buf, next_buf, PATH_MAX);
- if (len < 0)
- die ("Invalid symlink: %s", buf);
- next_buf[len] = '\0';
- buf = next_buf;
- buf_index = 1 - buf_index;
- next_buf = bufs[buf_index];
- } else
- break;
+ 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;
+ }
}
- if (*cwd && chdir(cwd))
- die ("Could not change back to '%s'", cwd);
-
- return buf;
+ return max_len;
}