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To: cygwin@cygwin.com
From: Eric Blake <ebb9@byu.net>
Subject:  Re: 1.5.24: data corruption problem with popen and gzip on a text  mounted filesystem
Date: Mon, 23 Jul 2007 19:56:48 +0000 (UTC)
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Hugh Secker-Walker <hugh <at> merl.com> writes:

> Interestingly, I had tried popen("gzip | dd of=outputfile", "wb") as a
> lower-level way to avoid what I guessed was a problem with gzip using
> the stdout.  The dd attempt didn't work.  This failure suggests to me
> that dd and gzip experience a similar problem in this popen() context,
> a problem that cat somehow avoids.

It looks like dd currently honors mount points.  You would need to use:

popen("gzip | dd of=outputfile oflag=binary", "wb")

to guarantee binary writes.  But I thought at one point I had patched dd to 
default to binary unless you used oflag=text; I'll have to investigate.

-- 
Eric Blake
volunteer cygwin coreutils maintainer



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