Re: [icqlib-dev] [patch] cast alignment fixes

[Bill S. <we...@ri...>]

On Tue, 5 Jun 2001, Lars Christensen wrote:

> Description: This patch fixes cast alignment bugs detected by using the
> -Wcast-align option for gcc. Although
> 
> 	*((DWORD*)&buffer[5]) = value;
> 
> may work on an intel processor, it is not portable because some
> architechtures (e.g. sparc) cannot copy DWORDS if they are not aligned on
> a multiple of 4 bytes. The attached patch fixes all occurences of such
> statements to:
> 
> 	memcpy(buffer + 5, &value, sizeof(DWORD));
> 
> The patches is tested and icqlib works on Sparc Solaris with is (UDP
> communication at least. TCP code is also changed, but untested - it does
> compile though). icqlib would about with a "bus error" or "segmentation
> fault" without this patch.

Interesting - I never realized you have to worry about alignment.

Why doesn't the compiler generate assembly code to just do the copy byte
by byte?  Any ideas? :)

I'll apply the patch of course, just wondering for future reference.

Bill