The readline() call returns partial data. Keep appending until the JSON buffer is complete.
This fixes: $ scripts/qmp/qmp-shell -v -p /tmp/qmp.sock Traceback (most recent call last): File "scripts/qmp/qmp-shell", line 456, in <module> main() File "scripts/qmp/qmp-shell", line 441, in main qemu.connect(negotiate) File "scripts/qmp/qmp-shell", line 284, in connect self._greeting = super(QMPShell, self).connect(negotiate) File "scripts/qmp/qmp.py", line 143, in connect return self.__negotiate_capabilities() File "scripts/qmp/qmp.py", line 71, in __negotiate_capabilities greeting = self.__json_read() File "scripts/qmp/qmp.py", line 85, in __json_read resp = json.loads(data) File "/usr/lib/python2.7/json/__init__.py", line 339, in loads return _default_decoder.decode(s) File "/usr/lib/python2.7/json/decoder.py", line 364, in decode obj, end = self.raw_decode(s, idx=_w(s, 0).end()) File "/usr/lib/python2.7/json/decoder.py", line 380, in raw_decode obj, end = self.scan_once(s, idx) ValueError: Expecting object: line 1 column 3 (char 2) Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org> --- Since v1: - addressed Daniel review: clean data after json.loads() succeeds - add a XXX comment Daniel suggested this is due to blocking i/o. I'm sure there is a nicer/more pythonic way to do this, but this works for me, sorry :) scripts/qmp/qmp.py | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/scripts/qmp/qmp.py b/scripts/qmp/qmp.py index 5c8cf6a056..14f0b48936 100644 --- a/scripts/qmp/qmp.py +++ b/scripts/qmp/qmp.py @@ -78,11 +78,18 @@ class QEMUMonitorProtocol(object): raise QMPCapabilitiesError def __json_read(self, only_event=False): + data = "" while True: - data = self.__sockfile.readline() - if not data: + tmp = self.__sockfile.readline() + if not tmp: return - resp = json.loads(data) + data += tmp + try: + resp = json.loads(data) + except ValueError: + # XXX: blindly loop, even if QEMU ever sends malformed data + continue + data = "" if 'event' in resp: self.logger.debug("<<< %s", resp) self.__events.append(resp) -- 2.17.1