From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41416) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YiP6C-0003C4-RX for qemu-devel@nongnu.org; Wed, 15 Apr 2015 11:19:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YiP6A-0000bO-34 for qemu-devel@nongnu.org; Wed, 15 Apr 2015 11:19:32 -0400 Received: from resqmta-po-08v.sys.comcast.net ([96.114.154.167]:58497) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YiP69-0000b3-SL for qemu-devel@nongnu.org; Wed, 15 Apr 2015 11:19:30 -0400 From: Eric Blake Date: Wed, 15 Apr 2015 09:19:23 -0600 Message-Id: <1429111163-27870-1-git-send-email-eblake@redhat.com> Subject: [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: qemu-devel@nongnu.org Cc: erik.rull@rdsoftware.de, paulo.vital@profitbricks.com, lcapitulino@redhat.com 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'"}} {"execute":"qmp_capabilities"} {"return": {}} {"execute":"qmp_capabilities"} {"error": {"class": "CommandNotFound", "desc": "Capabilities negotiation is already complete, command 'qmp_capabilities' ignored"}} {"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) { -- 2.1.0