From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55676) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YiRoX-0000na-R3 for qemu-devel@nongnu.org; Wed, 15 Apr 2015 14:13:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YiRoU-0004bm-K7 for qemu-devel@nongnu.org; Wed, 15 Apr 2015 14:13:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57833) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YiRoU-0004am-CR for qemu-devel@nongnu.org; Wed, 15 Apr 2015 14:13:26 -0400 Message-ID: <552EAA42.9020400@redhat.com> Date: Wed, 15 Apr 2015 14:13:22 -0400 From: John Snow MIME-Version: 1.0 References: <1429111163-27870-1-git-send-email-eblake@redhat.com> In-Reply-To: <1429111163-27870-1-git-send-email-eblake@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] qmp: Give saner messages related to qmp_capabilities misuse List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org Cc: erik.rull@rdsoftware.de, paulo.vital@profitbricks.com, lcapitulino@redhat.com On 04/15/2015 11:19 AM, Eric Blake wrote: > Pretending that QMP doesn't understand a command merely because > we are not in the right mode doesn't help first-time users figure > out what to do to correct things. Although the documentation for > QMP calls out capabilities negotiation, we should also make it > clear in our error messages what we were expecting. With this > patch, I now get the following transcript: > > $ ./x86_64-softmmu/qemu-system-x86_64 -qmp stdio -nodefaults > {"QMP": {"version": {"qemu": {"micro": 93, "minor": 2, "major": 2}, "package": ""}, "capabilities": []}} > {"execute":"huh"} > {"error": {"class": "CommandNotFound", "desc": "The command huh has not been found"}} > {"execute":"quit"} > {"error": {"class": "CommandNotFound", "desc": "Expecting capabilities negotiation with 'qmp_capabilities' before command 'quit'"}} Any particular reason why we should keep the "CommandNotFound" error class here? Backwards compat? Inertia? > {"execute":"qmp_capabilities"} > {"return": {}} > {"execute":"qmp_capabilities"} > {"error": {"class": "CommandNotFound", "desc": "Capabilities negotiation is already complete, command 'qmp_capabilities' ignored"}} Same here. > {"execute":"quit"} > {"return": {}} > {"timestamp": {"seconds": 1429110729, "microseconds": 181935}, "event": "SHUTDOWN"} > > Signed-off-by: Eric Blake > --- > > Based in part on this thread: > https://lists.gnu.org/archive/html/qemu-devel/2015-04/msg00831.html > > monitor.c | 23 +++++++++++++++++++---- > 1 file changed, 19 insertions(+), 4 deletions(-) > > diff --git a/monitor.c b/monitor.c > index 68873ec..9f37700 100644 > --- a/monitor.c > +++ b/monitor.c > @@ -4783,10 +4783,22 @@ static int monitor_can_read(void *opaque) > return (mon->suspend_cnt == 0) ? 1 : 0; > } > > -static int invalid_qmp_mode(const Monitor *mon, const mon_cmd_t *cmd) > +static bool invalid_qmp_mode(const Monitor *mon, const mon_cmd_t *cmd) > { > - int is_cap = cmd->mhandler.cmd_new == do_qmp_capabilities; > - return (qmp_cmd_mode(mon) ? is_cap : !is_cap); > + bool is_cap = cmd->mhandler.cmd_new == do_qmp_capabilities; > + if (is_cap && qmp_cmd_mode(mon)) { > + qerror_report(ERROR_CLASS_COMMAND_NOT_FOUND, > + "Capabilities negotiation is already complete, command " > + "'%s' ignored", cmd->name); > + return true; > + } > + if (!is_cap && !qmp_cmd_mode(mon)) { > + qerror_report(ERROR_CLASS_COMMAND_NOT_FOUND, > + "Expecting capabilities negotiation with " > + "'qmp_capabilities' before command '%s'", cmd->name); > + return true; > + } > + return false; > } > > /* > @@ -5080,11 +5092,14 @@ static void handle_qmp_command(JSONMessageParser *parser, QList *tokens) > cmd_name = qdict_get_str(input, "execute"); > trace_handle_qmp_command(mon, cmd_name); > cmd = qmp_find_cmd(cmd_name); > - if (!cmd || invalid_qmp_mode(mon, cmd)) { > + if (!cmd) { > qerror_report(ERROR_CLASS_COMMAND_NOT_FOUND, > "The command %s has not been found", cmd_name); > goto err_out; > } > + if (invalid_qmp_mode(mon, cmd)) { > + goto err_out; > + } > > obj = qdict_get(input, "arguments"); > if (!obj) { >