Export thread-safe version of 'has_symlink_leading_path()'

The threaded index preloading will want it, so that it can avoid
locking by simply using a per-thread symlink/directory cache.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: torvalds

cache.h

@@ -744,7 +744,17 @@ struct checkout {
 };
 
 extern int checkout_entry(struct cache_entry *ce, const struct checkout *state, char *topath);
+
+struct cache_def {
+	char path[PATH_MAX + 1];
+	int len;
+	int flags;
+	int track_flags;
+	int prefix_len_stat_func;
+};
+
 extern int has_symlink_leading_path(const char *name, int len);
+extern int threaded_has_symlink_leading_path(struct cache_def *, const char *, int);
 extern int has_symlink_or_noent_leading_path(const char *name, int len);
 extern int has_dirs_only_path(const char *name, int len, int prefix_len);
 extern void invalidate_lstat_cache(const char *name, int len);

symlinks.c

@@ -32,13 +32,7 @@ static int longest_path_match(const char *name_a, int len_a,
 	return match_len;
 }
 
-static struct cache_def {
-	char path[PATH_MAX + 1];
-	int len;
-	int flags;
-	int track_flags;
-	int prefix_len_stat_func;
-} default_cache;
+static struct cache_def default_cache;
 
 static inline void reset_lstat_cache(struct cache_def *cache)
 {
@@ -214,15 +208,20 @@ void clear_lstat_cache(void)
 
 #define USE_ONLY_LSTAT  0
 
+/*
+ * Return non-zero if path 'name' has a leading symlink component
+ */
+int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
+{
+	return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
+}
+
 /*
  * Return non-zero if path 'name' has a leading symlink component
  */
 int has_symlink_leading_path(const char *name, int len)
 {
-	struct cache_def *cache = &default_cache;	/* FIXME */
-	return lstat_cache(cache, name, len,
-			   FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) &
-		FL_SYMLINK;
+	return threaded_has_symlink_leading_path(&default_cache, name, len);
 }
 
 /*