windows: Provide a strdup variant safe when passing zero-length strings

src/libstrongswan/utils/windows.h

@@ -67,6 +67,21 @@ static inline void srandom(unsigned int seed)
 	srand(seed);
 }
 
+/**
+ * strdup(3), the Windows variant can't free(strdup("")) and others
+ */
+#define strdup strdup_windows
+static inline char* strdup_windows(const char *src)
+{
+	size_t len;
+	char *dst;
+
+	len = strlen(src) + 1;
+	dst = malloc(len);
+	memcpy(dst, src, len);
+	return dst;
+}
+
 /**
  * Provided via ws2_32
  */