qga: conditionalize schema for commands requiring utmpx

Rather than creating stubs for every command that just return
QERR_UNSUPPORTED, use 'if' conditions in the QAPI schema to
fully exclude generation of the get-users command on POSIX
platforms lacking required APIs.

The command will be rejected at QMP dispatch time instead,
avoiding reimplementing rejection by blocking the stub commands.
This changes the error message for affected commands from

    {"class": "CommandNotFound", "desc": "Command FOO has been disabled"}

to

    {"class": "CommandNotFound", "desc": "The command FOO has not been found"}

This has the additional benefit that the QGA protocol reference
now documents what conditions enable use of the command.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Message-ID: <20240712132459.3974109-17-berrange@redhat.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index d92fa0ec8727ec06773c26a4f4c1480b1268485c..a353f64ae68b31ea13757692ee3ba26ee987f7d2 100644 (file)
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1212,15 +1212,7 @@ GuestUserList *qmp_guest_get_users(Error **errp)
     return head;
 }
 
-#else
-
-GuestUserList *qmp_guest_get_users(Error **errp)
-{
-    error_setg(errp, QERR_UNSUPPORTED);
-    return NULL;
-}
-
-#endif
+#endif /* HAVE_UTMPX */
 
 /* Replace escaped special characters with their real values. The replacement
  * is done in place -- returned value is in the original string.

diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index cf1ad42519b89410158d4130fc238af30c26a5ed..0662a68c43443d7b6016e59bc2a5e6591220b9a2 100644 (file)
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -1414,7 +1414,8 @@
 # Since: 2.10
 ##
 { 'struct': 'GuestUser',
-  'data': { 'user': 'str', 'login-time': 'number', '*domain': 'str' } }
+  'data': { 'user': 'str', 'login-time': 'number', '*domain': 'str' },
+  'if': { 'any': ['CONFIG_WIN32', 'HAVE_UTMPX' ] } }
 
 ##
 # @guest-get-users:
@@ -1426,7 +1427,8 @@
 # Since: 2.10
 ##
 { 'command': 'guest-get-users',
-  'returns': ['GuestUser'] }
+  'returns': ['GuestUser'],
+  'if': { 'any': ['CONFIG_WIN32', 'HAVE_UTMPX' ] } }
 
 ##
 # @GuestTimezone: