qga: conditionalize schema for commands requiring fsfreeze

Rather than creating stubs for every command that just return
QERR_UNSUPPORTED, use 'if' conditions in the schema to fully
exclude generation of the filesystem freezing commands on POSIX
platforms lacking the 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: <20240712132459.3974109-14-berrange@redhat.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>

2 files changed, 10 insertions, 52 deletions

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index b7f96aa..9207cb7 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1144,39 +1144,6 @@ error:
 
 #endif /* HAVE_GETIFADDRS */
 
-#if !defined(CONFIG_FSFREEZE)
-
-GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **errp)
-{
-    error_setg(errp, QERR_UNSUPPORTED);
-
-    return 0;
-}
-
-int64_t qmp_guest_fsfreeze_freeze(Error **errp)
-{
-    error_setg(errp, QERR_UNSUPPORTED);
-
-    return 0;
-}
-
-int64_t qmp_guest_fsfreeze_freeze_list(bool has_mountpoints,
-                                       strList *mountpoints,
-                                       Error **errp)
-{
-    error_setg(errp, QERR_UNSUPPORTED);
-
-    return 0;
-}
-
-int64_t qmp_guest_fsfreeze_thaw(Error **errp)
-{
-    error_setg(errp, QERR_UNSUPPORTED);
-
-    return 0;
-}
-#endif /* CONFIG_FSFREEZE */
-
 #if !defined(CONFIG_FSTRIM)
 GuestFilesystemTrimResponse *
 qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
@@ -1189,20 +1156,6 @@ qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
 /* add unsupported commands to the list of blocked RPCs */
 GList *ga_command_init_blockedrpcs(GList *blockedrpcs)
 {
-#if !defined(CONFIG_FSFREEZE)
-    {
-        const char *list[] = {
-            "guest-fsfreeze-status",
-            "guest-fsfreeze-freeze", "guest-fsfreeze-freeze-list",
-            "guest-fsfreeze-thaw", NULL};
-        char **p = (char **)list;
-
-        while (*p) {
-            blockedrpcs = g_list_append(blockedrpcs, g_strdup(*p++));
-        }
-    }
-#endif
-
 #if !defined(CONFIG_FSTRIM)
     blockedrpcs = g_list_append(blockedrpcs, g_strdup("guest-fstrim"));
 #endif
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index de3fc46..62462f0 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -412,7 +412,8 @@
 # Since: 0.15.0
 ##
 { 'enum': 'GuestFsfreezeStatus',
-  'data': [ 'thawed', 'frozen' ] }
+  'data': [ 'thawed', 'frozen' ],
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSFREEZE'] } }
 
 ##
 # @guest-fsfreeze-status:
@@ -429,7 +430,8 @@
 # Since: 0.15.0
 ##
 { 'command': 'guest-fsfreeze-status',
-  'returns': 'GuestFsfreezeStatus' }
+  'returns': 'GuestFsfreezeStatus',
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSFREEZE'] } }
 
 ##
 # @guest-fsfreeze-freeze:
@@ -451,7 +453,8 @@
 # Since: 0.15.0
 ##
 { 'command': 'guest-fsfreeze-freeze',
-  'returns': 'int' }
+  'returns': 'int',
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSFREEZE'] } }
 
 ##
 # @guest-fsfreeze-freeze-list:
@@ -471,7 +474,8 @@
 ##
 { 'command': 'guest-fsfreeze-freeze-list',
   'data':    { '*mountpoints': ['str'] },
-  'returns': 'int' }
+  'returns': 'int',
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSFREEZE'] } }
 
 ##
 # @guest-fsfreeze-thaw:
@@ -488,7 +492,8 @@
 # Since: 0.15.0
 ##
 { 'command': 'guest-fsfreeze-thaw',
-  'returns': 'int' }
+  'returns': 'int',
+  'if': { 'any': ['CONFIG_WIN32', 'CONFIG_FSFREEZE'] } }
 
 ##
 # @GuestFilesystemTrimResult: