[Patch] Segfault on unaligned lseek() on /dev/sdX (was: [ITP] ddrescue 1.3)

Christopher Faylor cgf-use-the-mailinglist-please@cygwin.com
Fri May 18 19:45:00 GMT 2007

On Fri, May 18, 2007 at 09:02:15PM +0200, Christian Franke wrote:
>Cygwin 1.5.24-2 segfaults on unaligned lseek() on raw block devices with 
>sector size >512 bytes.
>$ dd skip=1000 bs=2047 if=/dev/scd0 of=/dev/null
>$ ddrescue -c 1 /dev/scd0 file.iso
>This is due to a fixed 512 byte buffer in fhandler_dev_floppy::lseek().
>It is still present in HEAD revision.
>The attached patch should fix. It should work for any sector size.
>(Smoke-)tested with 1.5.24-2 (too busy to test with current CVS, sorry).
>2007-05-18  Christian Franke <franke@computer.org>
>	* fhandler_floppy.cc (fhandler_dev_floppy::lseek): Fixed segfault on
>	unaligned seek due to fixed size buffer.

It seems like this could be done without the heavyweight use of malloc,
like use an automatic array of length 512 + 4 and calculate an aligned
address from that.


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