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From: Stefan Hajnoczi <stefanha@gmail.com>
Date: Fri, 30 Sep 2016 16:33:27 +0100
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Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v5] qemu-img: change opening
 method for the output in dd
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Reda Sallahi <fullmanet@gmail.com>, Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, qemu block <qemu-block@nongnu.org>, Max Reitz <mreitz@redhat.com>

On Tue, Sep 13, 2016 at 4:35 PM, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> On Fri, Aug 26, 2016 at 09:19:40AM +0200, Reda Sallahi wrote:
>> -    blk2 = img_open(image_opts, out.filename, out_fmt, BDRV_O_RDWR,
>> -                    false, false);
>> +    ret = access(out_filename, F_OK); /* Check if file exists */
>
> The QEMU block layer does not use POSIX file I/O because it needs to
> support protocols like iSCSI and ssh.
>
> The only way to test for the existence of a disk image is by opening it
> with block layer APIs.
>
> Can you just move the img_open() call from the else statement up here
> instead?

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