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Date: Fri, 13 Jul 2012 12:55:56 +0200
From: Christoph Hellwig <hch@lst.de>
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Subject: Re: [Qemu-devel] [RFC] introduce a dynamic library to expose
	qemu	block API
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>, Paolo Bonzini <pbonzini@redhat.com>, Wenchao Xia <xiawenc@linux.vnet.ibm.com>

On Fri, Jul 13, 2012 at 12:42:41PM +0200, Kevin Wolf wrote:
> It still feels a bit more like qemu-io-style operations. Not sure what
> your use case looks like exactly, but adding a qemu-io command that
> reads data from a file and writes it at a given offset into the images
> (or vice versa) should be easy. This would be more or less a qemu-dd.

We already have that if you read/write the whole image, it's called
qemu-img convert.

> If you need to get data from stdin or output it to stdout, then it might
> not be the right solution.

That is the use case.  We could appromite it by writing a temp file and
using qemu-img convert, but that's not very efficient.