From ee0f05f9a1dbcba4a4ac33cab2fe87ad5541fa02 Mon Sep 17 00:00:00 2001
From: Ivan Enderlin <ivan.enderlin@hoa-project.net>
Date: Mon, 10 Feb 2020 11:31:54 +0100
Subject: [PATCH] feat(runtime-c-api) `wasmer_memory_data_length` returns 0 if
 `memory` is NULL.

---
 lib/runtime-c-api/src/memory.rs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/lib/runtime-c-api/src/memory.rs b/lib/runtime-c-api/src/memory.rs
index 74bb82fe8..f8fd581da 100644
--- a/lib/runtime-c-api/src/memory.rs
+++ b/lib/runtime-c-api/src/memory.rs
@@ -198,10 +198,15 @@ pub extern "C" fn wasmer_memory_data(memory: *const wasmer_memory_t) -> *mut u8
 /// ```
 #[allow(clippy::cast_ptr_alignment)]
 #[no_mangle]
-pub extern "C" fn wasmer_memory_data_length(mem: *mut wasmer_memory_t) -> u32 {
-    let memory = mem as *mut Memory;
-    let Bytes(len) = unsafe { (*memory).size().bytes() };
-    len as u32
+pub extern "C" fn wasmer_memory_data_length(memory: *mut wasmer_memory_t) -> u32 {
+    if memory.is_null() {
+        return 0;
+    }
+
+    let memory = unsafe { &*(memory as *const Memory) };
+    let Bytes(length) = memory.size().bytes();
+
+    length as u32
 }
 
 /// Frees memory for the given Memory