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: Jeff Fan <jeff.fan@intel.com>
For pointer subtraction, the result is of type "ptrdiff_t". According to
the C11 standard (Committee Draft - April 12, 2011):
"When two pointers are subtracted, both shall point to elements of the
same array object, or one past the last element of the array object; the
result is the difference of the subscripts of the two array elements. The
size of the result is implementation-defined, and its type (a signed
integer type) is ptrdiff_t defined in the <stddef.h> header. If the result
is not representable in an object of that type, the behavior is
undefined."
In our codes, there are cases that the pointer subtraction is not
performed by pointers to elements of the same array object. This might
lead to potential issues, since the behavior is undefined according to C11
standard.
Also, since the size of type "ptrdiff_t" is implementation-defined. Some
static code checkers may warn that the pointer subtraction might underflow
first and then being cast to a bigger size. For example:
UINT8 *Ptr1, *Ptr2;
UINTN PtrDiff;
...
PtrDiff = (UINTN) (Ptr1 - Ptr2);
The commit will refine the pointer subtraction expressions by casting each
pointer to UINTN first and then perform the subtraction:
PtrDiff = (UINTN) Ptr1 - (UINTN) Ptr2;
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
It is the follow up of 3ab41b7a32
to replace UnicodeStrToAsciiStr/AsciiStrToUnicodeStr with
UnicodeStrToAsciiStrS/AsciiStrToUnicodeStrS.
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
LegacyBootManagerLib is a NULL class library to work with UefiBootManagerLib
providing legacy boot support.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17330 6f19259b-4bc3-4df7-8a09-765794883524
Hao Wu
Laszlo Ersek
Star Zeng
Ruiyu Ni