Xi: return BadValue on XIQueryVersion if the version is less than first call

Clients that use plugin systems may require multiple calls to
XIQueryVersion from different plugins. The current error handling requires
client-side synchronisation of version numbers.

The first call to XIQueryVersion defines the server behaviour. Once cached,
always return that version number to any clients. Unless a client requests a
version lower than the first defined one, then a BadValue must be returned
to be protocol-compatible.

Introduced in 2c23ef83b0e03e163aeeb06133538606886f4e9c

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>

1 files changed, 21 insertions, 20 deletions

diff --git a/Xi/xiqueryversion.c b/Xi/xiqueryversion.c
index fc0ca751b..6081c413d 100644
--- a/Xi/xiqueryversion.c
+++ b/Xi/xiqueryversion.c
@@ -70,28 +70,29 @@ ProcXIQueryVersion(ClientPtr client)
 
     pXIClient = dixLookupPrivate(&client->devPrivates, XIClientPrivateKey);
 
-    if (pXIClient->major_version &&
-           (stuff->major_version != pXIClient->major_version ||
-            stuff->minor_version != pXIClient->minor_version))
-    {
-        client->errorValue = stuff->major_version;
-        return BadValue;
+    if (pXIClient->major_version) {
+        if (version_compare(stuff->major_version, stuff->minor_version,
+                            pXIClient->major_version, pXIClient->minor_version) < 0) {
+            client->errorValue = stuff->major_version;
+            return BadValue;
+        }
+        major = pXIClient->major_version;
+        minor = pXIClient->minor_version;
+    } else {
+        if (version_compare(XIVersion.major_version, XIVersion.minor_version,
+                    stuff->major_version, stuff->minor_version) > 0) {
+            major = stuff->major_version;
+            minor = stuff->minor_version;
+        }
+        else {
+            major = XIVersion.major_version;
+            minor = XIVersion.minor_version;
+        }
+
+        pXIClient->major_version = major;
+        pXIClient->minor_version = minor;
     }
 
-
-    if (version_compare(XIVersion.major_version, XIVersion.minor_version,
-                        stuff->major_version, stuff->minor_version) > 0) {
-        major = stuff->major_version;
-        minor = stuff->minor_version;
-    }
-    else {
-        major = XIVersion.major_version;
-        minor = XIVersion.minor_version;
-    }
-
-    pXIClient->major_version = major;
-    pXIClient->minor_version = minor;
-
     memset(&rep, 0, sizeof(xXIQueryVersionReply));
     rep.repType = X_Reply;
     rep.RepType = X_XIQueryVersion;