From 89ecbdcaab6ad1510a9f2058c4585ab4c17be743 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Sat, 22 Jun 2024 17:19:28 +0100
Subject: win32: only access mode argument of open(2) if required

The wrapper function 'mingw_open()' should only read the optional
third argument if the 'O_CREAT' flag bit is set.

Adds 16 bytes.

(GitHub issue #425)
---
 win32/mingw.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/win32/mingw.c b/win32/mingw.c
index 49e1bcfa4..6ad514ad4 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -239,9 +239,11 @@ int mingw_open (const char *filename, int oflags, ...)
 		return fd;
 	}
 
-	va_start(args, oflags);
-	mode = va_arg(args, int);
-	va_end(args);
+	if ((oflags & O_CREAT)) {
+		va_start(args, oflags);
+		mode = va_arg(args, int);
+		va_end(args);
+	}
 
 	pmode = ((mode & S_IWUSR) ? _S_IWRITE : 0) |
 					((mode & S_IRUSR) ? _S_IREAD : 0);
-- 
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