On Jun 23, 2014, at 11:25 AM, Sathya Prakash <sathya.prak...@avagotech.com>
wrote:
> Thanks Andrew, Does the basetools code needs similar change to return the
> destination buffer when length is 0?
I’m not sure? The BaseTools code is only used by the build system. It looks
like there is a copy of CopyMem() in the CommonLib, and there is also a
CommonLibBinderCopyMem() function? I’m not sure if CopyMem() should get
replaced with CommonLibBinderCopyMem()? We would need to get some feedback from
the maintainer.
Thanks,
Andrew Fish
> -Sathya
>
> PS: My E-mail ID changed from sathya.prak...@lsi.com to
> sathya.prak...@avagotech.com. Please update your address book.
>
> From: Andrew Fish [mailto:af...@apple.com]
> Sent: Monday, June 23, 2014 12:14 PM
> To: edk2-devel@lists.sourceforge.net
> Subject: Re: [edk2] Where can I find CopyMem implementation.
>
>
> On Jun 23, 2014, at 11:01 AM, Sathya Prakash <sathya.prak...@avagotech.com>
> wrote:
>
>
> I would like to see the CopyMem implementation. Which source file I should
> look for it. I see some implementation in commonlib.c in basetools but I
> assume it wont be taken from there and instead will be used from boot
> services table. So how can I know about the implementation. The reason I
> want to look into that is, in reallocatepool, there is a possibility that
> the CopyMem can be called with 0 length. If CopyMem implementation is
> similar to what is in commonlib.c (as mentioned below), the 0 will be
> decremented and due to the type of length (UINTN) there might be some memory
> corruption.
>
>
>
> There are multiple CopyMem() implementations, as there are multiple instances
> of the BaseMemoryLib. You will need to look in your DSC, or build log, to see
> which instance of the BaseMemoryLib you are using.
>
>
> Please correct if my understanding is wrong.
>
>
>
> https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg/Library/BaseMemoryLibOptDxe/CopyMemWrapper.c
> /**
> Copies a source buffer to a destination buffer, and returns the destination
> buffer.
>
> This function copies Length bytes from SourceBuffer to DestinationBuffer,
> and returns
> DestinationBuffer. The implementation must be reentrant, and it must
> handle the case
> where SourceBuffer overlaps DestinationBuffer.
>
> If Length is greater than (MAX_ADDRESS - DestinationBuffer + 1), then
> ASSERT().
> If Length is greater than (MAX_ADDRESS - SourceBuffer + 1), then ASSERT().
>
> @param DestinationBuffer The pointer to the destination buffer of the
> memory copy.
> @param SourceBuffer The pointer to the source buffer of the memory
> copy.
> @param Length The number of bytes to copy from SourceBuffer
> to DestinationBuffer.
>
> @return DestinationBuffer.
>
> **/
> VOID *
> EFIAPI
> CopyMem (
> OUT VOID *DestinationBuffer,
> IN CONST VOID *SourceBuffer,
> IN UINTN Length
> )
> {
> if (Length == 0) {
> return DestinationBuffer;
> }
> ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)DestinationBuffer));
> ASSERT ((Length - 1) <= (MAX_ADDRESS - (UINTN)SourceBuffer));
>
> if (DestinationBuffer == SourceBuffer) {
> return DestinationBuffer;
> }
> return InternalMemCopyMem (DestinationBuffer, SourceBuffer, Length);
> }
>
> There is a check for a length of zero, ASSERT() macros for pointer overflow
> checks, and and check to make sure the pointers are not the same. After that
> it calls the assembly language code.
>
> Thanks,
>
> Andrew Fish
>
>
>
> VOID
> PeiCopyMem (
> IN VOID *Destination,
> IN VOID *Source,
> IN UINTN Length
> )
> /*++
>
> Routine Description:
>
> Copy Length bytes from Source to Destination.
>
> Arguments:
>
> Destination - Target of copy
>
> Source - Place to copy from
>
> Length - Number of bytes to copy
>
> Returns:
>
> None
>
> --*/
> {
> CHAR8 *Destination8;
> CHAR8 *Source8;
>
> Destination8 = Destination;
> Source8 = Source;
> while (Length--) {
> *(Destination8++) = *(Source8++);
> }
> }
>
> Thanks
> Sathya
>
> PS: My E-mail ID changed from sathya.prak...@lsi.com to
> sathya.prak...@avagotech.com. Please update your address book.
>
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