Commit 2d5a8346 authored by Eric Blake's avatar Eric Blake Committed by Luiz Capitulino
Browse files

qmp: Give saner messages related to qmp_capabilities misuse 



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: default avatarEric Blake <eblake@redhat.com>
Tested-By: default avatarKashyap Chamarthy <kchamart@redhat.com>
Reviewed-by: default avatarPaulo Vital <paulo.vital@profitbricks.com>
Reviewed-by: default avatarJohn Snow <jsnow@redhat.com>
Signed-off-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
parent 43d0a2c1

monitor.c

+19 −4
Original line number Original line Diff line number Diff line
@@ -4783,10 +4783,22 @@ static int monitor_can_read(void *opaque) 
    return (mon->suspend_cnt == 0) ? 1 : 0;

    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;

    bool is_cap = cmd->mhandler.cmd_new == do_qmp_capabilities;

    return (qmp_cmd_mode(mon) ? is_cap : !is_cap);

    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");

    cmd_name = qdict_get_str(input, "execute");

    trace_handle_qmp_command(mon, cmd_name);

    trace_handle_qmp_command(mon, cmd_name);

    cmd = qmp_find_cmd(cmd_name);

    cmd = qmp_find_cmd(cmd_name);

    if (!cmd || invalid_qmp_mode(mon, cmd)) {

    if (!cmd) {

        qerror_report(ERROR_CLASS_COMMAND_NOT_FOUND,

        qerror_report(ERROR_CLASS_COMMAND_NOT_FOUND,

                      "The command %s has not been found", cmd_name);

                      "The command %s has not been found", cmd_name);

        goto err_out;

        goto err_out;

    }

    }

    if (invalid_qmp_mode(mon, cmd)) {

        goto err_out;

    }





    obj = qdict_get(input, "arguments");

    obj = qdict_get(input, "arguments");

    if (!obj) {

    if (!obj) {