[ros-dev] [ros-diffs] [jgardou] 54462: [RTL] - explicitly truncate some values, so it doesn't count as an error for compiler/MSVC runtime checker

[Jérôme Gardou]

Here the variable is an ULONGLONG and we pass it to a macro that casts 
it to a DWORD, and that's what it should do. Although casting and 
truncating is the same from a "normal" compiler point of view, a run 
time checker would raise a warning if you cast a value superior to 
0xFFFFFFFF to a DWORD. Truncating it explicitly tells it "yes, I 
truncate this value, not for avoiding compiler warning, but because 
that's what I want". See r54460 to see which kind of bugs such checkers 
could help to fix.

See also http://msdn.microsoft.com/en-us/magazine/cc301374.aspx for some 
in depth details, and, of course, cl documentation.
Also, gcc has this kind of functionalities, it's called GNAT.

Mit freundlichen Grüssen. :-)
Jérôme

Le 24/11/2011 00:03, Timo Kreuzer a écrit :
> That doesn't make much sense.
> Whats the point of the LOWORD() macro, if not truncating it ?
> Fix the macro if its broken.
>
>
> Am 20.11.2011 20:45, schrieb jgardou at svn.reactos.org:
>> Author: jgardou
>> Date: Sun Nov 20 19:45:06 2011
>> New Revision: 54462
>>
>> URL: http://svn.reactos.org/svn/reactos?rev=54462&view=rev
>> Log:
>> [RTL]
>> - explicitly truncate some values, so it doesn't count as an error 
>> for compiler/MSVC runtime checker
>>
>> Modified:
>>      trunk/reactos/lib/rtl/image.c
>>
>> Modified: trunk/reactos/lib/rtl/image.c
>> URL: 
>> http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/image.c?rev=54462&r1=54461&r2=54462&view=diff
>> ============================================================================== 
>>
>> --- trunk/reactos/lib/rtl/image.c [iso-8859-1] (original)
>> +++ trunk/reactos/lib/rtl/image.c [iso-8859-1] Sun Nov 20 19:45:06 2011
>> @@ -369,7 +369,7 @@
>>   {
>>       SHORT Offset;
>>       USHORT Type;
>> -    USHORT i;
>> +    ULONG i;
>>       PUSHORT ShortPtr;
>>       PULONG LongPtr;
>>       PULONGLONG LongLongPtr;
>> @@ -379,7 +379,6 @@
>>           Offset = SWAPW(*TypeOffset)&  0xFFF;
>>           Type = SWAPW(*TypeOffset)>>  12;
>>           ShortPtr = (PUSHORT)(RVA(Address, Offset));
>> -
>>           /*
>>           * Don't relocate within the relocation section itself.
>>           * GCC/LD generates sometimes relocation records for the 
>> relocation section.
>> @@ -398,16 +397,16 @@
>>               break;
>>
>>           case IMAGE_REL_BASED_HIGH:
>> -            *ShortPtr = HIWORD(MAKELONG(0, *ShortPtr) + (LONG)Delta);
>> +            *ShortPtr = HIWORD(MAKELONG(0, *ShortPtr) + (Delta&  
>> 0xFFFFFFFF));
>>               break;
>>
>>           case IMAGE_REL_BASED_LOW:
>> -            *ShortPtr = SWAPW(*ShortPtr) + LOWORD(Delta);
>> +            *ShortPtr = SWAPW(*ShortPtr) + LOWORD(Delta&  0xFFFF);
>>               break;
>>
>>           case IMAGE_REL_BASED_HIGHLOW:
>>               LongPtr = (PULONG)RVA(Address, Offset);
>> -            *LongPtr = SWAPD(*LongPtr) + (ULONG)Delta;
>> +            *LongPtr = SWAPD(*LongPtr) + (Delta&  0xFFFFFFFF);
>>               break;
>>
>>           case IMAGE_REL_BASED_DIR64:
>>
>>
>>
>
>
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