mount_image.c: Use well-defined check in flags_writable()

No effect on Linux, but it's more correct to explicitly check for
the O_ACCMODE bits being O_WRONLY or O_RDWR.

diff --git a/src/mount_image.c b/src/mount_image.c
index 04be3f6..586722e 100644 (file)
--- a/src/mount_image.c
+++ b/src/mount_image.c
@@ -164,7 +164,8 @@ get_lookup_flags(const struct wimfs_context *ctx)
 static inline int
 flags_writable(int open_flags)
 {
-       return open_flags & (O_RDWR | O_WRONLY);
+       int accmode = (open_flags & O_ACCMODE);
+       return (accmode == O_RDWR || accmode == O_WRONLY);
 }
 
 /*