Re: [Qemu-devel] [PATCH v2 02/26] libqtest: Work around a "QMP wants a newline" bug

[Eric Blake]

On 02/26/2017 03:43 PM, Markus Armbruster wrote:
> The next commit is going to add a test that calls qmp("null").
> Curiously, this hangs.  Here's why.
> 
> qmp_fd_sendv() doesn't send newlines.  Not even when @fmt contains
> some.  At first glance, the QMP parser seems to be fine with that.
> However, it turns out that it fails to react to input until it sees
> either a newline, an object or an array.  To reproduce, feed to a QMP
> monitor like this:
> 
>     $ echo -n 'null' | socat UNIX:/work/armbru/images/test-qmp STDIO

I didn't point this out last time, but 'echo -n' is not portable.  On
the other hand, it is sufficient for the example in the commit message,
so no need to change.

>     {"QMP": {"version": {"qemu": {"micro": 50, "minor": 8, "major": 2}, 
> "package": " (v2.8.0-1195-gf84141e-dirty)"}, "capabilities": []}}
> 
> No output after the greeting.
> 

> Work around this QMP bug by having qmp_fd_sendv() append a newline.
> 
> Signed-off-by: Markus Armbruster <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>

R-b stands.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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