API/ABI change: XCBSendRequest returns the sequence number instead of using an out-parameter. Now 0 is a special sequence number indicating failure.

src/c-client.xsl

@@ -615,7 +615,7 @@ authorization from the authors.
       <l>xcb_parts[<xsl:value-of select="3 + position() * 2"/>].iov_len = -xcb_parts[<xsl:value-of select="2 + position() * 2"/>].iov_len &amp; 3;</l>
     </xsl:for-each>
 
-    <l>XCBSendRequest(c, &amp;xcb_ret.sequence, <!--
+    <l>xcb_ret.sequence = XCBSendRequest(c, <!--
     --><xsl:choose>
          <xsl:when test="@has-reply">XCB_REQUEST_CHECKED</xsl:when>
          <xsl:otherwise>0</xsl:otherwise>

src/xcb_in.c

@@ -238,6 +238,10 @@ void *XCBWaitForReply(XCBConnection *c, unsigned int request, XCBGenericError **
     if(e)
         *e = 0;
 
+    /* If an error occurred when issuing the request, fail immediately. */
+    if(!request)
+        return 0;
+
     pthread_mutex_lock(&c->iolock);
 
     /* If this request has not been written yet, write it. */

src/xcb_out.c

@@ -69,15 +69,14 @@ CARD32 XCBGetMaximumRequestLength(XCBConnection *c)
     return c->out.maximum_request_length;
 }
 
-int XCBSendRequest(XCBConnection *c, unsigned int *request, int flags, struct iovec *vector, const XCBProtocolRequest *req)
+unsigned int XCBSendRequest(XCBConnection *c, int flags, struct iovec *vector, const XCBProtocolRequest *req)
 {
-    int ret;
+    unsigned int request;
     CARD32 prefix[2];
     int veclen = req->count;
     enum workarounds workaround = WORKAROUND_NONE;
 
     assert(c != 0);
-    assert(request != 0);
     assert(vector != 0);
     assert(req->count > 0);
 
@@ -92,8 +91,8 @@ int XCBSendRequest(XCBConnection *c, unsigned int *request, int flags, struct io
         if(req->ext)
         {
             const XCBQueryExtensionRep *extension = XCBGetExtensionData(c, req->ext);
-            /* TODO: better error handling here, please! */
-            assert(extension && extension->present);
+            if(!(extension && extension->present))
+                return 0;
             ((CARD8 *) vector[0].iov_base)[0] = extension->major_opcode;
             ((CARD8 *) vector[0].iov_base)[1] = req->opcode;
         }
@@ -148,20 +147,22 @@ int XCBSendRequest(XCBConnection *c, unsigned int *request, int flags, struct io
     if(req->isvoid && !force_sequence_wrap(c))
     {
         pthread_mutex_unlock(&c->iolock);
-        return -1;
+        return 0;
     }
 
     /* wait for other writing threads to get out of my way. */
     while(c->out.writing)
         pthread_cond_wait(&c->out.cond, &c->iolock);
 
-    *request = ++c->out.request;
+    request = ++c->out.request;
+    assert(request != 0);
 
-    _xcb_in_expect_reply(c, *request, workaround, flags);
+    _xcb_in_expect_reply(c, request, workaround, flags);
 
-    ret = _xcb_out_write_block(c, vector, veclen);
+    if(!_xcb_out_write_block(c, vector, veclen))
+        request = 0;
     pthread_mutex_unlock(&c->iolock);
-    return ret;
+    return request;
 }
 
 int XCBFlush(XCBConnection *c)

src/xcbext.h

@@ -56,7 +56,7 @@ enum XCBSendRequestFlags {
     XCB_REQUEST_RAW = 1 << 1
 };
 
-int XCBSendRequest(XCBConnection *c, unsigned int *sequence, int flags, struct iovec *vector, const XCBProtocolRequest *request);
+unsigned int XCBSendRequest(XCBConnection *c, int flags, struct iovec *vector, const XCBProtocolRequest *request);
 
 
 /* xcb_in.c */