Re: [PATCH v7 0/4] VNC-related HMP/QMP fixes

[Fabian Ebner]

Am 28.10.21 um 21:37 schrieb Markus Armbruster:
> Markus Armbruster <armbru@redhat.com> writes:

----8<----

> diff --git a/qapi/ui.json b/qapi/ui.json
> index 5292617b44..39ca0b5ead 100644
> --- a/qapi/ui.json
> +++ b/qapi/ui.json
> @@ -69,8 +69,10 @@
>     'base': { 'protocol': 'DisplayProtocol',
>               'password': 'str' },
>     'discriminator': 'protocol',
> -  'data': { 'vnc': 'SetPasswordOptionsVnc',
> -            'spice': 'SetPasswordOptionsSpice' } }
> +  'data': { 'vnc': { 'type': 'SetPasswordOptionsVnc',
> +                     'if': 'CONFIG_VNC' },
> +            'spice': { 'type': 'SetPasswordOptionsSpice',
> +                       'if': 'CONFIG_SPICE' } } }
>   
>   ##
>   # @SetPasswordOptionsSpice:
> @@ -155,7 +157,8 @@
>     'base': { 'protocol': 'DisplayProtocol',
>               'time': 'str' },
>     'discriminator': 'protocol',
> -  'data': { 'vnc': 'ExpirePasswordOptionsVnc' } }
> +  'data': { 'vnc': { 'type': 'ExpirePasswordOptionsVnc',
> +                     'if': 'CONFIG_VNC' } } }
>   

So I decided to give the #ifdef approach a go, but if I configure with 
--disable-spice --disable-vnc, even with the above conditionals, it is 
still be possible to issue a set_password qmp command, which will then 
lead to an abort() in the generated code (and the patched 
qmp_set_password below would do the same if it could be reached):

Thread 1 (Thread 0x7f4a86701ec0 (LWP 40487) "qemu-system-x86"):
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0x00007f4a90d72537 in __GI_abort () at abort.c:79
#2  0x00005583ca03cef3 in visit_type_SetPasswordOptions_members 
(v=v@entry=0x5583cc6cccc0, obj=obj@entry=0x7ffe5bfc3ee0, 
errp=errp@entry=0x0) at qapi/qapi-visit-ui.c:71
#3  0x00005583ca5df72f in qmp_marshal_set_password (args=<optimized 
out>, ret=<optimized out>, errp=0x7f4a85d96ea0) at 
qapi/qapi-commands-ui.c:49
#4  0x00005583ca5e89e9 in do_qmp_dispatch_bh (opaque=0x7f4a85d96eb0) at 
../qapi/qmp-dispatch.c:129
#5  0x00005583ca605494 in aio_bh_call (bh=0x7f4a78009270) at 
../util/async.c:141

Is that expected? Should I add a conditional for {set,expire}_password 
in the schema too, and add an
#if defined(CONFIG_SPICE) || defined(CONFIG_VNC)
around the whole {hmp,qmp}_{set,expire}_password functions/declarations 
in C?

Or maybe that's a good indication that it's really not worth it ;)?

P.S. Thank you for the QAPI-related explanation in the other mail!

----8<----

> diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
> index 4825d0cbea..69a9c2977a 100644
> --- a/monitor/qmp-cmds.c
> +++ b/monitor/qmp-cmds.c
> @@ -167,18 +167,26 @@ void qmp_set_password(SetPasswordOptions *opts, Error 
> **errp)
>   {
>       int rc = 0;
>   
> -    if (opts->protocol == DISPLAY_PROTOCOL_SPICE) {
> +    switch (opts->protocol) {
> +#ifdef CONFIG_SPICE
> +    case DISPLAY_PROTOCOL_SPICE:
>           if (!qemu_using_spice(errp)) {
>               return;
>           }
>           rc = qemu_spice.set_passwd(opts->password,
>                   opts->u.spice.connected == SET_PASSWORD_ACTION_FAIL,
>                   opts->u.spice.connected == SET_PASSWORD_ACTION_DISCONNECT);
> -    } else {
> -        assert(opts->protocol == DISPLAY_PROTOCOL_VNC);
> +        break;
> +#endif
> +#ifdef CONFIG_VNC
> +    case DISPLAY_PROTOCOL_VNC:
>           /* Note that setting an empty password will not disable login through
>            * this interface. */
>           rc = vnc_display_password(opts->u.vnc.display, opts->password);
> +        break;
> +#endif
> +    default:
> +        abort();
>       }
>   
>       if (rc != 0) {
> @@ -202,14 +210,22 @@ void qmp_expire_password(ExpirePasswordOptions *opts, 
> Error **errp)
>           when = strtoull(whenstr, NULL, 10);
>       }
>   
> -    if (opts->protocol == DISPLAY_PROTOCOL_SPICE) {
> +    switch (opts->protocol) {
> +#ifdef CONFIG_SPICE
> +    case DISPLAY_PROTOCOL_SPICE:
>           if (!qemu_using_spice(errp)) {
>               return;
>           }
>           rc = qemu_spice.set_pw_expire(when);
> -    } else {
> -        assert(opts->protocol == DISPLAY_PROTOCOL_VNC);
> +        break;
> +#endif
> +#ifdef CONFIG_VNC
> +    case DISPLAY_PROTOCOL_VNC:
>           rc = vnc_display_pw_expire(opts->u.vnc.display, when);
> +        break;
> +#endif
> +    default:
> +        abort();
>       }
>   
>       if (rc != 0) {