Thanks Andrew, Does the basetools code needs similar change to return the
destination buffer when length is 0?
-Sathya
PS: My E-mail ID changed from [email protected] to
[email protected]. Please update your address book.
*From:* Andrew Fish [mailto:[email protected]]
*Sent:* Monday, June 23, 2014 12:14 PM
*To:* [email protected]
*Subject:* Re: [edk2] Where can I find CopyMem implementation.
On Jun 23, 2014, at 11:01 AM, Sathya Prakash <[email protected]>
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 [email protected] to
[email protected]. Please update your address book.
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Leverages Graph Analysis for Fast Processing & Easy Data Exploration
http://p.sf.net/sfu/hpccsystems
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