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author | Hao Wu <hao.a.wu@intel.com> | 2017-02-24 10:01:34 +0800 |
---|---|---|
committer | Hao Wu <hao.a.wu@intel.com> | 2017-03-06 14:33:20 +0800 |
commit | 16f6922709952c7ad468dcdee6ef94b3e5a3cd90 (patch) | |
tree | 999456e2e6812457d5c0b32b969ac0eed2b02149 /MdeModulePkg/Library/UefiHiiLib | |
parent | 95ba3d92dca2616715e2af89d2bbeca9577a3e2c (diff) | |
download | edk2-16f6922709952c7ad468dcdee6ef94b3e5a3cd90.zip edk2-16f6922709952c7ad468dcdee6ef94b3e5a3cd90.tar.gz edk2-16f6922709952c7ad468dcdee6ef94b3e5a3cd90.tar.bz2 |
MdeModulePkg: 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: Feng Tian <feng.tian@intel.com>
Diffstat (limited to 'MdeModulePkg/Library/UefiHiiLib')
-rw-r--r-- | MdeModulePkg/Library/UefiHiiLib/HiiLib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/MdeModulePkg/Library/UefiHiiLib/HiiLib.c b/MdeModulePkg/Library/UefiHiiLib/HiiLib.c index b740d43..a2abf26 100644 --- a/MdeModulePkg/Library/UefiHiiLib/HiiLib.c +++ b/MdeModulePkg/Library/UefiHiiLib/HiiLib.c @@ -1874,7 +1874,7 @@ GetBlockDataInfo ( //
// Check whether VarBuffer is enough
//
- if ((UINTN) (Offset + Width) > MaxBufferSize) {
+ if ((UINT32)Offset + Width > MaxBufferSize) {
DataBuffer = ReallocatePool (
MaxBufferSize,
Offset + Width + HII_LIB_DEFAULT_VARSTORE_SIZE,
|