Bug in pread/pwrite ?

Christopher Faylor cgf-use-the-mailinglist-please@cygwin.com
Thu Mar 8 23:44:00 GMT 2007

On Fri, Mar 09, 2007 at 12:05:47AM +0100, Christophe GRENIER wrote:
>After upgrading my compiler from cygwin 1.5.17-1 to 1.5.24-2, TestDisk
>& PhotoRec, my GPL data recovery programs, were unable to read data!

Please calm down.

>I have written a little program (see attachment) to reproduce the
>problem.  As administrator, run "test_pread /dev/sda".
>The program use lseek() to go the disk end, the function failed.  Now
>pread will now always failed, because it ends (cf
>cygwin-1.5.24-2/newlib/libc/unix/pread.c) by an lseek to the backuped
>location.  The same problem also applies to pwrite.
>I don't know if the following patch is a good idea:

Patches sent here are really supposed to be tested.  You obviously
didn't test this because your proposed patch doesn't modify a function
that Cygwin actually uses.

The pread() that Cygwin does uses is in fhandler_disk_file.cc.

All of that aside, I don't see how ignoring an lseek() failure
could be considered to be a good thing.


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