From: Laszlo Ersek <lersek@redhat.com>
To: edk2-devel-01 <edk2-devel@lists.01.org>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>,
Liming Gao <liming.gao@intel.com>,
Michael D Kinney <michael.d.kinney@intel.com>,
Sean Brogan <sean.brogan@microsoft.com>
Subject: [PATCH 3/4] MdePkg/BaseSafeIntLib: clean up parentheses in MIN_INT64_MAGNITUDE
Date: Thu, 15 Feb 2018 19:36:37 +0100 [thread overview]
Message-ID: <20180215183638.18578-4-lersek@redhat.com> (raw)
In-Reply-To: <20180215183638.18578-1-lersek@redhat.com>
The definition of the MIN_INT64_MAGNITUDE macro is correct, but it's
harder to read than necessary: the sub-expression
(( (UINT64) - (MIN_INT64 + 1) ))
is doubly parenthesized. Reusing one pair of the outer parens, rewrite the
sub-expression (without change in meaning) so that the minus sign cannot
be mistaken for subtraction:
( (UINT64)(- (MIN_INT64 + 1)) )
The resultant macro definition matches the following expressions in
SafeInt64Mult():
> //
> // Avoid negating the most negative number.
> //
> UnsignedMultiplicand = ((UINT64)(- (Multiplicand + 1))) + 1;
and
> //
> // Avoid negating the most negative number.
> //
> UnsignedMultiplier = ((UINT64)(- (Multiplier + 1))) + 1;
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
MdePkg/Library/BaseSafeIntLib/SafeIntLib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
index 56d97cf65601..de91ffeca2a5 100644
--- a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
+++ b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
@@ -33,7 +33,7 @@
//
// Magnitude of MIN_INT64 as expressed by a UINT64 number.
//
-#define MIN_INT64_MAGNITUDE ((((UINT64) - (MIN_INT64 + 1))) + 1)
+#define MIN_INT64_MAGNITUDE (((UINT64)(- (MIN_INT64 + 1))) + 1)
//
// Conversion functions
--
2.14.1.3.gb7cf6e02401b
next prev parent reply other threads:[~2018-02-15 18:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-15 18:36 [PATCH 0/4] MdePkg/BaseSafeIntLib: fix undefined behavior in INT64 Sub/Add/Mult Laszlo Ersek
2018-02-15 18:36 ` [PATCH 1/4] MdePkg/BaseSafeIntLib: fix undefined behavior in SafeInt64Sub() Laszlo Ersek
2018-02-15 18:36 ` [PATCH 2/4] MdePkg/BaseSafeIntLib: fix undefined behavior in SafeInt64Add() Laszlo Ersek
2018-02-15 18:36 ` Laszlo Ersek [this message]
2018-02-15 18:36 ` [PATCH 4/4] MdePkg/BaseSafeIntLib: fix undefined behavior in SafeInt64Mult() Laszlo Ersek
2018-02-16 11:28 ` [PATCH 0/4] MdePkg/BaseSafeIntLib: fix undefined behavior in INT64 Sub/Add/Mult Ard Biesheuvel
2018-02-16 20:44 ` Laszlo Ersek
2018-02-16 18:11 ` Kinney, Michael D
2018-02-16 20:49 ` Laszlo Ersek
2018-02-17 3:07 ` Kinney, Michael D
2018-02-21 11:00 ` Laszlo Ersek
2018-02-21 18:10 ` Ard Biesheuvel
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