Re: 1.5.0: Problem with fseeko() after fdopen() (gold star alert)

[Igor Pechtchanski <pechtcha at cs dot nyu dot edu>]

On Thu, 24 Jul 2003, Christopher Faylor wrote:

> On Thu, Jul 24, 2003 at 09:11:51AM -0700, David Rothenberger wrote:
> Content-Description: message body text
> >I'm running 1.5.0 with all the latest test packages installed.
> >
> >I recently noticed a problem with the test release of patch and its
> >ability to read from stdin.  I started to investigate and have
> >extracted the problematic code from patch into a test program.
> >
> >The program (and patch) use open() to create/open a file and then
> >use fdopen() on the resulting file descriptor.  The file is opened
> >in RW mode, some data is written to it, the file is flushed, and
> >then an attempt is made to seek to the beginning of the file.
> >
> >This last seek fails.  The seek is done using fseeko().  If fseek()
> >is used instead, all is fine.
> >
> >I did a bit of debugging in newlib and determined that fdopen()
> >doesn't set pfp->_seek64, which causes the problem.  If I use
> >fopen() to create the file, then pfp->_seek64 is set (since fopen()
> >ends up calling fopen64()).
>
> Thanks very much for the analysis.  This is a flaw in the 1.5.0 version
> of cygwin.
>
> I've submitted a patch request to fix this to the newlib mailing list
> which I expect to fix the problem.  It does cause patch to operate
> correctly when linked with a new cygwin dll.
>
> When the patch is accepted, I'll generate a new cygwin snapshot but it
> won't be very useful since the patch program will still not work right.
> So, after the usual extensive snapshot testing, I'll roll up a cygwin
> 1.5.1 and then regenerate patch.exe.
>
> I have to wonder how many of the many 1.5.0 test packages use fdopen and
> fseek, though.  I hate to say it but package developers might have to go
> through the pain of rebuilding everything for 1.5.x again.
>
> Please give this man a gold star for going to the effort of tracking
> down the problem in source code!
>
> cgf

And with no prompting, either.  Yup, I thought he deserved one.  Done.
	Igor
-- 
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