Re: [edk2] [PATCH 5/5] MdeModulePkg/PartitionDxe: remove always false comparison

2017-09-12 Thread Zeng, Star 
Reviewed-by: Star Zeng 

-Original Message-
From: Laszlo Ersek [mailto:ler...@redhat.com] 
Sent: Sunday, September 10, 2017 8:13 AM
To: edk2-devel-01 
Cc: Ard Biesheuvel ; Dong, Eric 
; Paulo Alcantara ; Ni, Ruiyu 
; Zeng, Star 
Subject: [PATCH 5/5] MdeModulePkg/PartitionDxe: remove always false comparison

In the expression

  (RemainderByMediaBlockSize != 0 ||
   Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE)

the second expression is only evaluated if the first expression is false.

If the first expression is false, i.e.,

  RemainderByMediaBlockSize == 0

then UDF_LOGICAL_SECTOR_SIZE is a whole multiple of "Media->BlockSize", which 
implies

  UDF_LOGICAL_SECTOR_SIZE >= Media->BlockSize.

Therefore whenever

  Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE

is evaluated, it is false.

The expression

  ((expression) || FALSE)

is equivalent to

  (expression).

Cc: Ard Biesheuvel 
Cc: Eric Dong 
Cc: Paulo Alcantara 
Cc: Ruiyu Ni 
Cc: Star Zeng 
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek 
---
 MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c 
b/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
index c491ef25f47e..3347b48421a8 100644
--- a/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
+++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
@@ -252,12 +252,11 @@ PartitionInstallUdfChildHandles (
   DivU64x32Remainder (
 UDF_LOGICAL_SECTOR_SIZE,   // Dividend
 Media->BlockSize,  // Divisor
  // Remainder
 );
-  if (RemainderByMediaBlockSize != 0 ||
-  Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE) {
+  if (RemainderByMediaBlockSize != 0) {
 return EFI_NOT_FOUND;
   }
 
   DevicePathNode = DevicePath;
   while (!IsDevicePathEnd (DevicePathNode)) {
--
2.14.1.3.gb7cf6e02401b

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[edk2] [PATCH 5/5] MdeModulePkg/PartitionDxe: remove always false comparison

2017-09-09 Thread Laszlo Ersek 
In the expression

  (RemainderByMediaBlockSize != 0 ||
   Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE)

the second expression is only evaluated if the first expression is false.

If the first expression is false, i.e.,

  RemainderByMediaBlockSize == 0

then UDF_LOGICAL_SECTOR_SIZE is a whole multiple of "Media->BlockSize",
which implies

  UDF_LOGICAL_SECTOR_SIZE >= Media->BlockSize.

Therefore whenever

  Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE

is evaluated, it is false.

The expression

  ((expression) || FALSE)

is equivalent to

  (expression).

Cc: Ard Biesheuvel 
Cc: Eric Dong 
Cc: Paulo Alcantara 
Cc: Ruiyu Ni 
Cc: Star Zeng 
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek 
---
 MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c 
b/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
index c491ef25f47e..3347b48421a8 100644
--- a/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
+++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
@@ -252,12 +252,11 @@ PartitionInstallUdfChildHandles (
   DivU64x32Remainder (
 UDF_LOGICAL_SECTOR_SIZE,   // Dividend
 Media->BlockSize,  // Divisor
  // Remainder
 );
-  if (RemainderByMediaBlockSize != 0 ||
-  Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE) {
+  if (RemainderByMediaBlockSize != 0) {
 return EFI_NOT_FOUND;
   }
 
   DevicePathNode = DevicePath;
   while (!IsDevicePathEnd (DevicePathNode)) {
-- 
2.14.1.3.gb7cf6e02401b

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