Re: fix memcpy() overlap

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: PostgreSQL Patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: fix memcpy() overlap
Date: 2004-02-02 22:18:08
Message-ID: 401ECCA0.2000809@dunslane.net
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Stephan Szabo wrote:

>On Mon, 2 Feb 2004, Tom Lane wrote:
>
>
>
>>Neil Conway <neilc(at)samurai(dot)com> writes:
>>
>>
>>>I don't know of a memcpy() implementation that would actually bail out
>>>if called with two equal pointers, but perhaps there is one in
>>>existence somewhere.
>>>
>>>
>>This isn't a bug, and I see no reason to clutter the code just to shut
>>up valgrind.
>>
>>
>
>Isn't memcpy on overlapping (even entirely overlapping) buffers undefined
>behavior unless the count is 0?
>
>
>

On my Linux box the man page says:

DESCRIPTION
The memcpy() function copies n bytes from memory area src to
memory
area dest. The memory areas may not overlap. Use memmove(3)
if the
memory areas do overlap.

cheers

andrew

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