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diff --git a/symlinks.c b/symlinks.c
index c69556acf8d41cf0ccf728de732356105e7df0fa..1d6b35b858020300f502e2a9341b82d4fa8a61fd 100644 (file)
--- a/symlinks.c
+++ b/symlinks.c
#include "cache.h"
-static struct cache_def {
- char path[PATH_MAX];
- int len;
- int flags;
- int track_flags;
-} cache;
-
/*
* Returns the length (on a path component basis) of the longest
- * common prefix match of 'name' and the cached path string.
+ * common prefix match of 'name_a' and 'name_b'.
*/
-static inline int longest_match_lstat_cache(int len, const char *name)
+static int longest_path_match(const char *name_a, int len_a,
+ const char *name_b, int len_b,
+ 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] == '/')
+ max_len = len_a < len_b ? len_a : len_b;
+ while (i < max_len && name_a[i] == name_b[i]) {
+ if (name_a[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] == '/')
- 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))
- match_len = len;
+ /*
+ * Is 'name_b' a substring of 'name_a', the other way around,
+ * or is 'name_a' and 'name_b' the exact same string?
+ */
+ if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
+ (len_a < len_b && name_b[len_a] == '/') ||
+ (len_a == len_b))) {
+ match_len_prev = match_len;
+ match_len = i;
+ }
+ *previous_slash = match_len_prev;
return match_len;
}
-static inline void reset_lstat_cache(int track_flags)
+static struct cache_def {
+ char path[PATH_MAX + 1];
+ int len;
+ int flags;
+ int track_flags;
+ int prefix_len_stat_func;
+} cache;
+
+static inline void reset_lstat_cache(void)
{
cache.path[0] = '\0';
cache.len = 0;
cache.flags = 0;
- cache.track_flags = track_flags;
+ /*
+ * The track_flags and prefix_len_stat_func members is only
+ * set by the safeguard rule inside lstat_cache()
+ */
}
#define FL_DIR (1 << 0)
#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, 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)
+static int lstat_cache(const char *name, int len,
+ 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;
- if (cache.track_flags != track_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 value of
- * track_flags does not match with the last supplied
- * value.
+ * As a safeguard rule 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);
+ reset_lstat_cache();
+ cache.track_flags = track_flags;
+ cache.prefix_len_stat_func = 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);
+ match_len = last_slash =
+ longest_path_match(name, len, cache.path, cache.len,
+ &previous_slash);
match_flags = cache.flags & track_flags & (FL_NOENT|FL_SYMLINK);
if (match_flags && match_len == cache.len)
return match_flags;
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;
* for the moment!
*/
save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
- if (save_flags && last_slash > 0 && last_slash < PATH_MAX) {
+ 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) {
+ } else if ((track_flags & FL_DIR) &&
+ 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 or a
cache.len = last_slash_dir;
cache.flags = FL_DIR;
} else {
- reset_lstat_cache(track_flags);
+ reset_lstat_cache();
}
return ret_flags;
}
+/*
+ * Invalidate the given 'name' from the cache, if 'name' matches
+ * completely with the cache.
+ */
+void invalidate_lstat_cache(const char *name, int len)
+{
+ int match_len, previous_slash;
+
+ match_len = longest_path_match(name, len, cache.path, cache.len,
+ &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();
+ }
+}
+
+/*
+ * Completely clear the contents of the cache
+ */
+void clear_lstat_cache(void)
+{
+ reset_lstat_cache();
+}
+
+#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)
+int has_symlink_leading_path(const char *name, int len)
{
- return lstat_cache(len, name,
- FL_SYMLINK|FL_DIR) &
+ return lstat_cache(name, len,
+ 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)
+int has_symlink_or_noent_leading_path(const char *name, int len)
{
- return lstat_cache(len, name,
- FL_SYMLINK|FL_NOENT|FL_DIR) &
+ return lstat_cache(name, len,
+ 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(const char *name, int len, int prefix_len)
+{
+ return lstat_cache(name, len,
+ FL_DIR|FL_FULLPATH, prefix_len) &
+ FL_DIR;
+}
+
+static struct removal_def {
+ char path[PATH_MAX];
+ int len;
+} removal;
+
+static void do_remove_scheduled_dirs(int new_len)
+{
+ while (removal.len > new_len) {
+ removal.path[removal.len] = '\0';
+ if (rmdir(removal.path))
+ break;
+ do {
+ removal.len--;
+ } while (removal.len > new_len &&
+ removal.path[removal.len] != '/');
+ }
+ removal.len = new_len;
+ return;
+}
+
+void schedule_dir_for_removal(const char *name, int len)
+{
+ int match_len, last_slash, i, previous_slash;
+
+ match_len = last_slash = i =
+ longest_path_match(name, len, removal.path, removal.len,
+ &previous_slash);
+ /* Find last slash inside 'name' */
+ while (i < len) {
+ if (name[i] == '/')
+ last_slash = i;
+ i++;
+ }
+
+ /*
+ * If we are about to go down the directory tree, we check if
+ * we must first go upwards the tree, such that we then can
+ * remove possible empty directories as we go upwards.
+ */
+ if (match_len < last_slash && match_len < removal.len)
+ do_remove_scheduled_dirs(match_len);
+ /*
+ * If we go deeper down the directory tree, we only need to
+ * save the new path components as we go down.
+ */
+ if (match_len < last_slash) {
+ memcpy(&removal.path[match_len], &name[match_len],
+ last_slash - match_len);
+ removal.len = last_slash;
+ }
+ return;
+}
+
+void remove_scheduled_dirs(void)
+{
+ do_remove_scheduled_dirs(0);
+ return;
+}