From fcffed23ada90e00cd8de359d1913c3c4ebfd697 Mon Sep 17 00:00:00 2001
From: Yusuke Endoh <mame@ruby-lang.org>
Date: Fri, 29 Nov 2024 13:28:03 +0900
Subject: [PATCH] Do not depend on the evaluation order of C arguments

The evaluation order of C arguments is unspecified.
`RSTRING_LEN(str)` would fails if the conversion to a String by
`StringValuePtr` is not done yet.

Coverity Scan found this issue.
---
 ext/fiddle/pointer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ext/fiddle/pointer.c b/ext/fiddle/pointer.c
index 00bd76e9..10a6cc70 100644
--- a/ext/fiddle/pointer.c
+++ b/ext/fiddle/pointer.c
@@ -827,7 +827,8 @@ rb_fiddle_ptr_read_mem(VALUE klass, VALUE address, VALUE len)
 static VALUE
 rb_fiddle_ptr_write_mem(VALUE klass, VALUE addr, VALUE str)
 {
-    memcpy(NUM2PTR(addr), StringValuePtr(str), RSTRING_LEN(str));
+    const char *ptr = StringValuePtr(str);
+    memcpy(NUM2PTR(addr), ptr, RSTRING_LEN(str));
     return str;
 }