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diff --git a/symlinks.c b/symlinks.c
index 49fb4d8bc2fc7fba70e18c9d9ec54cb5ba590da5..f262b7c44b387f4c60901124c30585b3c059fa73 100644 (file)
--- a/symlinks.c
+++ b/symlinks.c
#include "cache.h"
static struct cache_def {
- char path[PATH_MAX];
+ char path[PATH_MAX + 1];
int len;
int flags;
+ int track_flags;
+ int prefix_len_stat_func;
} cache;
/*
* Returns the length (on a path component basis) of the longest
* common prefix match of 'name' and the cached path string.
*/
-static inline int longest_match_lstat_cache(int len, const char *name)
+static inline int longest_match_lstat_cache(int len, const char *name,
+ int *previous_slash)
{
- int max_len, match_len = 0, i = 0;
+ int max_len, match_len = 0, match_len_prev = 0, i = 0;
max_len = len < cache.len ? len : cache.len;
while (i < max_len && name[i] == cache.path[i]) {
- if (name[i] == '/')
+ if (name[i] == '/') {
+ match_len_prev = match_len;
match_len = i;
+ }
i++;
}
/* Is the cached path string a substring of 'name'? */
- if (i == cache.len && cache.len < len && name[cache.len] == '/')
+ if (i == cache.len && cache.len < len && name[cache.len] == '/') {
+ match_len_prev = match_len;
match_len = cache.len;
/* Is 'name' a substring of the cached path string? */
- else if ((i == len && len < cache.len && cache.path[len] == '/') ||
- (i == len && len == cache.len))
+ } else if ((i == len && len < cache.len && cache.path[len] == '/') ||
+ (i == len && len == cache.len)) {
+ match_len_prev = match_len;
match_len = len;
+ }
+ *previous_slash = match_len_prev;
return match_len;
}
-static inline void reset_lstat_cache(void)
+static inline void reset_lstat_cache(int track_flags, int prefix_len_stat_func)
{
cache.path[0] = '\0';
cache.len = 0;
cache.flags = 0;
+ cache.track_flags = track_flags;
+ cache.prefix_len_stat_func = prefix_len_stat_func;
}
#define FL_DIR (1 << 0)
-#define FL_SYMLINK (1 << 1)
-#define FL_LSTATERR (1 << 2)
-#define FL_ERR (1 << 3)
+#define FL_NOENT (1 << 1)
+#define FL_SYMLINK (1 << 2)
+#define FL_LSTATERR (1 << 3)
+#define FL_ERR (1 << 4)
+#define FL_FULLPATH (1 << 5)
/*
* Check if name 'name' of length 'len' has a symlink leading
- * component, or if the directory exists and is real.
+ * component, or if the directory exists and is real, or not.
*
* To speed up the check, some information is allowed to be cached.
- * This can be indicated by the 'track_flags' argument.
+ * This can be indicated by the 'track_flags' argument, which also can
+ * be used to indicate that we should check the full path.
+ *
+ * The 'prefix_len_stat_func' parameter can be used to set the length
+ * of the prefix, where the cache should use the stat() function
+ * instead of the lstat() function to test each path component.
*/
static int lstat_cache(int len, const char *name,
- int track_flags)
+ int track_flags, int prefix_len_stat_func)
{
- int match_len, last_slash, last_slash_dir;
- int match_flags, ret_flags, save_flags, max_len;
+ int match_len, last_slash, last_slash_dir, previous_slash;
+ int match_flags, ret_flags, save_flags, max_len, ret;
struct stat st;
- /*
- * Check to see if we have a match from the cache for the
- * symlink path type.
- */
- match_len = last_slash = longest_match_lstat_cache(len, name);
- match_flags = cache.flags & track_flags & FL_SYMLINK;
- if (match_flags && match_len == cache.len)
- return match_flags;
- /*
- * If we now have match_len > 0, we would know that the
- * matched part will always be a directory.
- *
- * Also, if we are tracking directories and 'name' is a
- * substring of the cache on a path component basis, we can
- * return immediately.
- */
- match_flags = track_flags & FL_DIR;
- if (match_flags && len == match_len)
- return match_flags;
+ if (cache.track_flags != track_flags ||
+ cache.prefix_len_stat_func != prefix_len_stat_func) {
+ /*
+ * As a safeguard we clear the cache if the values of
+ * track_flags and/or prefix_len_stat_func does not
+ * match with the last supplied values.
+ */
+ reset_lstat_cache(track_flags, prefix_len_stat_func);
+ match_len = last_slash = 0;
+ } else {
+ /*
+ * Check to see if we have a match from the cache for
+ * the 2 "excluding" path types.
+ */
+ match_len = last_slash =
+ longest_match_lstat_cache(len, name, &previous_slash);
+ match_flags = cache.flags & track_flags & (FL_NOENT|FL_SYMLINK);
+ if (match_flags && match_len == cache.len)
+ return match_flags;
+ /*
+ * If we now have match_len > 0, we would know that
+ * the matched part will always be a directory.
+ *
+ * Also, if we are tracking directories and 'name' is
+ * a substring of the cache on a path component basis,
+ * we can return immediately.
+ */
+ match_flags = track_flags & FL_DIR;
+ if (match_flags && len == match_len)
+ return match_flags;
+ }
/*
* Okay, no match from the cache so far, so now we have to
cache.path[match_len] = name[match_len];
match_len++;
} while (match_len < max_len && name[match_len] != '/');
- if (match_len >= max_len)
+ if (match_len >= max_len && !(track_flags & FL_FULLPATH))
break;
last_slash = match_len;
cache.path[last_slash] = '\0';
- if (lstat(cache.path, &st)) {
+ if (last_slash <= prefix_len_stat_func)
+ ret = stat(cache.path, &st);
+ else
+ ret = lstat(cache.path, &st);
+
+ if (ret) {
ret_flags = FL_LSTATERR;
+ if (errno == ENOENT)
+ ret_flags |= FL_NOENT;
} else if (S_ISDIR(st.st_mode)) {
last_slash_dir = last_slash;
continue;
}
/*
- * At the end update the cache. Note that max 2 different
- * path types, FL_SYMLINK and FL_DIR, can be cached for the
- * moment!
+ * At the end update the cache. Note that max 3 different
+ * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
+ * for the moment!
*/
- save_flags = ret_flags & track_flags & FL_SYMLINK;
- if (save_flags && last_slash > 0 && last_slash < PATH_MAX) {
+ save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
+ if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
cache.path[last_slash] = '\0';
cache.len = last_slash;
cache.flags = save_flags;
} else if (track_flags & FL_DIR &&
- last_slash_dir > 0 && last_slash_dir < PATH_MAX) {
+ last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
/*
* We have a separate test for the directory case,
- * since it could be that we have found a symlink and
- * the track_flags says that we cannot cache this
- * fact, so the cache would then have been left empty
- * in this case.
+ * since it could be that we have found a symlink or a
+ * non-existing directory and the track_flags says
+ * that we cannot cache this fact, so the cache would
+ * then have been left empty in this case.
*
* But if we are allowed to track real directories, we
* can still cache the path components before the last
- * one (the found symlink component).
+ * one (the found symlink or non-existing component).
*/
cache.path[last_slash_dir] = '\0';
cache.len = last_slash_dir;
cache.flags = FL_DIR;
} else {
- reset_lstat_cache();
+ reset_lstat_cache(track_flags, prefix_len_stat_func);
}
return ret_flags;
}
+/*
+ * Invalidate the given 'name' from the cache, if 'name' matches
+ * completely with the cache.
+ */
+void invalidate_lstat_cache(int len, const char *name)
+{
+ int match_len, previous_slash;
+
+ match_len = longest_match_lstat_cache(len, name, &previous_slash);
+ if (len == match_len) {
+ if ((cache.track_flags & FL_DIR) && previous_slash > 0) {
+ cache.path[previous_slash] = '\0';
+ cache.len = previous_slash;
+ cache.flags = FL_DIR;
+ } else
+ reset_lstat_cache(cache.track_flags,
+ cache.prefix_len_stat_func);
+ }
+}
+
+/*
+ * Completely clear the contents of the cache
+ */
+void clear_lstat_cache(void)
+{
+ reset_lstat_cache(0, 0);
+}
+
+#define USE_ONLY_LSTAT 0
+
/*
* Return non-zero if path 'name' has a leading symlink component
*/
int has_symlink_leading_path(int len, const char *name)
{
return lstat_cache(len, name,
- FL_SYMLINK|FL_DIR) &
+ FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) &
FL_SYMLINK;
}
+
+/*
+ * Return non-zero if path 'name' has a leading symlink component or
+ * if some leading path component does not exists.
+ */
+int has_symlink_or_noent_leading_path(int len, const char *name)
+{
+ return lstat_cache(len, name,
+ FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) &
+ (FL_SYMLINK|FL_NOENT);
+}
+
+/*
+ * Return non-zero if all path components of 'name' exists as a
+ * directory. If prefix_len > 0, we will test with the stat()
+ * function instead of the lstat() function for a prefix length of
+ * 'prefix_len', thus we then allow for symlinks in the prefix part as
+ * long as those points to real existing directories.
+ */
+int has_dirs_only_path(int len, const char *name, int prefix_len)
+{
+ return lstat_cache(len, name,
+ FL_DIR|FL_FULLPATH, prefix_len) &
+ FL_DIR;
+}