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Re: [Qemu-devel] [PATCH for-2.9] rbd: Fix regression in legacy key/value

From: Max Reitz
Subject: Re: [Qemu-devel] [PATCH for-2.9] rbd: Fix regression in legacy key/values containing escaped :
Date: Fri, 31 Mar 2017 19:45:05 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0

On 31.03.2017 17:27, Eric Blake wrote:
> Commit c7cacb3 accidentally broke legacy key-value parsing through
> pseudo-filename parsing of -drive file=rbd://..., for any key that
> contains an escaped ':'.  Such a key is surprisingly common, thanks
> to mon_host specifying a 'host:port' string.  The break happens
> because passing things from QDict through QemuOpts back to another
> QDict requires that we pack our parsed key/value pairs into a string,
> and then reparse that string, but the intermediate string that we
> created ("key1=value1:key2=value2") lost the \: escaping that was
> present in the original, so that we could no longer see which : were
> used as separators vs. those used as part of the original input.
> Fix it by collecting the key/value pairs through a QList, and
> sending that list on a round trip through a JSON QString (as in
> '["key1","value1","key2","value2"]') on its way through QemuOpts,
> rather than hand-rolling our own string.  Since the string is only
> handled internally, this was faster than creating a full-blown
> struct of '[{"key1":"value1"},{"key2":"value2"}]', and safer at
> guaranteeing order compared to '{"key1":"value1","key2":"value2"}'.
> It would be nicer if we didn't have to round-trip through QemuOpts
> in the first place, but that's a much bigger task for later.
> Reproducer:
> ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -nographic -qmp stdio \
> -drive 'file=rbd:volumes/volume-ea141b5c-cdb3-4765-910d-e7008b209a70'\
> ':id=compute:key=AQAVkvxXAAAAABAA9ZxWFYdRmV+DSwKr7BKKXg=='\
> ':auth_supported=cephx\;none:mon_host=\:6789'\
> ',format=raw,if=none,id=drive-virtio-disk0,'\
> 'serial=ea141b5c-cdb3-4765-910d-e7008b209a70,cache=writeback'
> Even without an RBD setup, this serves a test of whether we get
> the incorrect parser error of:
> qemu-system-x86_64: -drive file=rbd:...cache=writeback: conf option 6789 has 
> no value
> or the correct behavior of hanging while trying to connect to
> the requested mon_host of
> Reported-by: Alexandru Avadanii <address@hidden>
> Signed-off-by: Eric Blake <address@hidden>
> ---
>  block/rbd.c | 83 
> +++++++++++++++++++++++++++++++------------------------------
>  1 file changed, 42 insertions(+), 41 deletions(-)

Reviewed-by: Max Reitz <address@hidden>

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