From: Gao Xiang <hsiangkao@linux.alibaba.com>
Date: Mon, 20 May 2024 17:20:57 +0000 (+0800)
Subject: safemath: Add ALIGN_UP_OVF() which checks for an overflow
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ba39de62f91302f7eb95e78dc8ce9c086f74df8;p=thirdparty%2Fgrub.git

safemath: Add ALIGN_UP_OVF() which checks for an overflow

The following EROFS patch will use this helper to handle
ALIGN_UP() overflow.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---

diff --git a/include/grub/safemath.h b/include/grub/safemath.h
index fbd9b5925..e032f63a0 100644
--- a/include/grub/safemath.h
+++ b/include/grub/safemath.h
@@ -32,6 +32,21 @@
 
 #define grub_cast(a, res)	grub_add ((a), 0, (res))
 
+/*
+ * It's caller's responsibility to check "align" does not equal 0 and
+ * is power of 2.
+ */
+#define ALIGN_UP_OVF(v, align, res) 			\
+({							\
+  bool __failed;					\
+  typeof(v) __a = ((typeof(v))(align) - 1);		\
+							\
+  __failed = grub_add (v, __a, res);			\
+  if (__failed == false)				\
+    *(res) &= ~__a;					\
+  __failed;						\
+})
+
 #else
 #error gcc 5.1 or newer or clang 8.0 or newer is required
 #endif