NetworkPkg: Refine casting expression result to bigger size

There are cases that the operands of an expression are all with rank less
than UINT64/INT64 and the result of the expression is explicitly cast to
UINT64/INT64 to fit the target size.

An example will be:
UINT32 a,b;
// a and b can be any unsigned int type with rank less than UINT64, like
// UINT8, UINT16, etc.
UINT64 c;
c = (UINT64) (a + b);

Some static code checkers may warn that the expression result might
overflow within the rank of "int" (integer promotions) and the result is
then cast to a bigger size.

The commit refines codes by the following rules:
1). When the expression is possible to overflow the range of unsigned int/
int:
c = (UINT64)a + b;

2). When the expression will not overflow within the rank of "int", remove
the explicit type casts:
c = a + b;

3). When the expression will be cast to pointer of possible greater size:
UINT32 a,b;
VOID *c;
c = (VOID *)(UINTN)(a + b); --> c = (VOID *)((UINTN)a + b);

4). When one side of a comparison expression contains only operands with
rank less than UINT32:
UINT8 a;
UINT16 b;
UINTN c;
if ((UINTN)(a + b) > c) {...} --> if (((UINT32)a + b) > c) {...}

For rule 4), if we remove the 'UINTN' type cast like:
if (a + b > c) {...}
The VS compiler will complain with warning C4018 (signed/unsigned
mismatch, level 3 warning) due to promoting 'a + b' to type 'int'.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/NetworkPkg/IpSecDxe/IpSecConfigImpl.h b/NetworkPkg/IpSecDxe/IpSecConfigImpl.h
index 3e365dae4a..23e68805ad 100644
--- a/NetworkPkg/IpSecDxe/IpSecConfigImpl.h
+++ b/NetworkPkg/IpSecDxe/IpSecConfigImpl.h
@@ -1,7 +1,7 @@
 /** @file

   Definitions related to IPSEC_CONFIG_PROTOCOL implementations.

 

-  Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>

+  Copyright (c) 2009 - 2017, Intel Corporation. All rights reserved.<BR>

 

   This program and the accompanying materials

   are licensed and made available under the terms and conditions of the BSD License

@@ -38,7 +38,7 @@
 #define IPSECCONFIG_VARIABLE_NAME       L"IpSecConfig"

 #define IPSECCONFIG_STATUS_NAME         L"IpSecStatus"

 

-#define SIZE_OF_SPD_SELECTOR(x) (UINTN) (sizeof (EFI_IPSEC_SPD_SELECTOR) \

+#define SIZE_OF_SPD_SELECTOR(x) (sizeof (EFI_IPSEC_SPD_SELECTOR) \

        + sizeof (EFI_IP_ADDRESS_INFO) * ((x)->LocalAddressCount + (x)->RemoteAddressCount))

 

 #define FIX_REF_BUF_ADDR(addr, base)    addr = (VOID *) ((UINTN) (addr) - (UINTN) (base))