db/update/InotifyQueue: use StringAfterPrefix()

src/db/update/InotifyQueue.cxx

@@ -24,8 +24,6 @@
 #include "Log.hxx"
 #include "util/StringCompare.hxx"
 
-#include <string.h>
-
 /**
  * Wait this long after the last change before calling
  * update_enqueue().  This increases the probability that updates can
@@ -55,14 +53,16 @@ InotifyQueue::OnTimeout()
 	}
 }
 
+gcc_pure
 static bool
 path_in(const char *path, const char *possible_parent)
 {
-	size_t length = strlen(possible_parent);
+	if (StringIsEmpty(path))
+		return true;
 
-	return StringIsEmpty(path) ||
-		(memcmp(possible_parent, path, length) == 0 &&
-		 (path[length] == 0 || path[length] == '/'));
+	auto rest = StringAfterPrefix(path, possible_parent);
+	return rest != nullptr &&
+		(StringIsEmpty(rest) || rest[0] == '/');
 }
 
 void