[PATCH] Xi: Allow clients to ask for 2.3 and then 2.2 without failing

[Keith Packard]

This allows different sub-systems within the same application to
request different Xi versions without either getting old behaviour
everywhere or simply failing with a BadValue.

Signed-off-by: Keith Packard <keithp at keithp.com>
---
 Xi/xiqueryversion.c | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/Xi/xiqueryversion.c b/Xi/xiqueryversion.c
index b807a53..6c7b9c0 100644
--- a/Xi/xiqueryversion.c
+++ b/Xi/xiqueryversion.c
@@ -71,13 +71,37 @@ ProcXIQueryVersion(ClientPtr client)
     pXIClient = dixLookupPrivate(&client->devPrivates, XIClientPrivateKey);
 
     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;
+
+        /* Check to see if the client has only ever asked
+         * for version 2.2 or higher
+         */
+        if (version_compare(stuff->major_version, stuff->minor_version, 2, 2) >= 0 &&
+            version_compare(pXIClient->major_version, pXIClient->minor_version, 2, 2) >= 0)
+        {
+
+            /* As of version 2.2, Peter promises to never again break
+             * backward compatibility, so we'll return the requested
+             * version to the client but leave the server internal
+             * version set to the highest requested value
+             */
+            major = stuff->major_version;
+            minor = stuff->minor_version;
+            if (version_compare(stuff->major_version, stuff->minor_version,
+                                pXIClient->major_version, pXIClient->minor_version) > 0)
+            {
+                pXIClient->major_version = stuff->major_version;
+                pXIClient->minor_version = stuff->minor_version;
+            }
+        } else {
+            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;
         }
-        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) {
-- 
1.8.3.1