Re: [Qemu-devel] [PATCH 14/19] Add a query-argv command to QMP

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/07/2010 09:42 AM, Daniel P. Berrange wrote:
> Add a new QMP command called 'query-argv' to information about the command
> line arguments supported by the QEMU binary. This is intended to remove the
> need for apps to parse '-help' output.
>    

This is just as bad as parsing -help output IMHO.

The problem with something like this is that it discourages people from 
using proper APIs to get at capabilities information.

Regards,

Anthony Liguori

>      [
>          {
>              "name": "help",
>          },
>          {
>              "name": "M",
>              "parameters": [
>                  {
>                  }
>              ]
>          },
>      ]
>
> NB, command line args which accept parameters have a non-zero length
> parameters list. The element of the list is currently empty though
> since the parameter names are not easily available in QEMU source in
> a format suitable for exposing as a stable ABI.
>
> Signed-off-by: Daniel P. Berrange<berrange@redhat.com>
> ---
>   monitor.c |    8 ++++++
>   monitor.h |    2 +
>   vl.c      |   74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 84 insertions(+), 0 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index d55b27b..1c5157d 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -2544,6 +2544,14 @@ static const mon_cmd_t info_cmds[] = {
>           .mhandler.info_new = do_info_commands,
>       },
>       {
> +        .name       = "argv",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "list QEMU command line argv",
> +        .user_print = monitor_user_noop,
> +        .mhandler.info_new = do_info_argv,
> +    },
> +    {
>           .name       = "network",
>           .args_type  = "",
>           .params     = "",
> diff --git a/monitor.h b/monitor.h
> index ea15469..46b7a0e 100644
> --- a/monitor.h
> +++ b/monitor.h
> @@ -55,4 +55,6 @@ typedef void (MonitorCompletion)(void *opaque, QObject *ret_data);
>
>   void monitor_set_error(Monitor *mon, QError *qerror);
>
> +void do_info_argv(Monitor *mon, QObject **data);
> +
>   #endif /* !MONITOR_H */
> diff --git a/vl.c b/vl.c
> index 8043fac..a76c673 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1987,6 +1987,80 @@ static void version(void)
>       printf("QEMU emulator version " QEMU_VERSION QEMU_PKGVERSION ", Copyright (c) 2003-2008 Fabrice Bellard\n");
>   }
>
> +
> +/**
> + * do_info_argv():
> + *
> + * Provide info about the command line arguments
> + * supported by the QEMU binary. The returned
> + * data is a QList with one QDict entry for  each named
> + * argument. Each entry's QDict contains the following
> + * keys
> + *
> + *  'name': the command argument name (eg 'drive' for -drive arg)
> + *  'parameters': list of parameter values (if any)
> + *
> + * NB, the 'parameters' key is omitted completely if
> + * the argument has no associated value.
> + *
> + * XXXX details of the parameters are not yet filled in
> + * since this info is not easily available
> + *
> + *     [
> + *         {
> + *             "name": "help",
> + *             "parameters": [
> + *             ]
> + *         },
> + *         {
> + *             "name": "M",
> + *             "parameters": [
> + *                 {
> + *                 }
> + *             ]
> + *         },
> + *     ]
> + */
> +void do_info_argv(Monitor *mon, QObject **data)
> +{
> +    QList *args = qlist_new();
> +    struct {
> +       const char *name;
> +       int has_arg;
> +       const char *help;
> +    } options_help[] = {
> +#define DEF(option, opt_arg, opt_enum, opt_help, arch_mask)     \
> +        { option, opt_arg },
> +#define DEFHEADING(text)
> +#define HAS_ARG 1
> +#include "qemu-options.h"
> +#undef DEF
> +#undef DEFHEADING
> +#undef HAS_ARG
> +       { NULL, 0 },
> +    };
> +    int i;
> +
> +    for (i = 0 ; options_help[i].name != NULL ; i++) {
> +	QObject *opt;
> +
> +	if (options_help[i].has_arg) {
> +	    /* XXX actually fill in the parameter details */
> +	    opt = qobject_from_jsonf("{ 'name': %s, 'parameters': [] }",
> +				     options_help[i].name);
> +	} else {
> +	    opt = qobject_from_jsonf("{ 'name': %s }",
> +				     options_help[i].name);
> +	}
> +
> +
> +	qlist_append_obj(args, opt);
> +    }
> +
> +    *data = QOBJECT(args);
> +}
> +
> +
>   static void help(int exitcode)
>   {
>       const char *options_help =
>