1 files changed, 14 insertions, 0 deletions
diff --git a/string.c b/string.c
index 387786fe07..72240b8506 100644
--- a/string.c
+++ b/string.c
@@ -343,6 +343,20 @@ str_frozen_check(VALUE s)
     }
 }
 
+size_t
+rb_str_capacity(VALUE str)
+{
+    if (STR_EMBED_P(str)) {
+	return RSTRING_EMBED_LEN_MAX;
+    }
+    else if (STR_NOCAPA_P(str)) {
+	return RSTRING(str)->as.heap.len;
+    }
+    else {
+	return RSTRING(str)->as.heap.aux.capa;
+    }
+}
+
 static inline VALUE
 str_alloc(VALUE klass)
 {