Tweak to previous API change: Require that spare iovecs fall before vector[0]. Leave vector in well-defined state.

2 files changed, 13 insertions, 12 deletions

diff --git a/src/c-client.xsl b/src/c-client.xsl
index 568e46c..1e37ea9 100644
--- a/src/c-client.xsl
+++ b/src/c-client.xsl
@@ -596,30 +596,30 @@ authorization from the authors.
                          mode="assign" />
 
     <l />
-    <l>xcb_parts[0].iov_base = &amp;xcb_out;</l>
-    <l>xcb_parts[0].iov_len = sizeof(xcb_out);</l>
-    <l>xcb_parts[1].iov_base = 0;</l>
-    <l>xcb_parts[1].iov_len = -xcb_parts[0].iov_len &amp; 3;</l>
+    <l>xcb_parts[2].iov_base = &amp;xcb_out;</l>
+    <l>xcb_parts[2].iov_len = sizeof(xcb_out);</l>
+    <l>xcb_parts[3].iov_base = 0;</l>
+    <l>xcb_parts[3].iov_len = -xcb_parts[2].iov_len &amp; 3;</l>
 
     <xsl:for-each select="$struct/list">
-      <l>xcb_parts[<xsl:value-of select="position() * 2"/>].iov_base = (void *) <!--
+      <l>xcb_parts[<xsl:value-of select="2 + position() * 2"/>].iov_base = (void *) <!--
       --><xsl:value-of select="@name" />;</l>
-      <l>xcb_parts[<xsl:value-of select="position() * 2"/>].iov_len = <!--
+      <l>xcb_parts[<xsl:value-of select="2 + position() * 2"/>].iov_len = <!--
       --><xsl:apply-templates mode="output-expression" /><!--
       --><xsl:if test="not(@type = 'void')">
         <xsl:text> * sizeof(</xsl:text>
         <xsl:value-of select="@type" />
         <xsl:text>)</xsl:text>
       </xsl:if>;</l>
-      <l>xcb_parts[<xsl:value-of select="1 + position() * 2"/>].iov_base = 0;</l>
-      <l>xcb_parts[<xsl:value-of select="1 + position() * 2"/>].iov_len = -xcb_parts[<xsl:value-of select="position() * 2"/>].iov_len &amp; 3;</l>
+      <l>xcb_parts[<xsl:value-of select="3 + position() * 2"/>].iov_base = 0;</l>
+      <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, <!--
     --><xsl:choose>
          <xsl:when test="@has-reply">XCB_REQUEST_CHECKED</xsl:when>
          <xsl:otherwise>0</xsl:otherwise>
-       </xsl:choose>, xcb_parts, &amp;xcb_req);</l>
+       </xsl:choose>, xcb_parts + 2, &amp;xcb_req);</l>
     <l>return xcb_ret;</l>
   </xsl:template>
 
diff --git a/src/xcb_out.c b/src/xcb_out.c
index 78ec8ca..b201565 100644
--- a/src/xcb_out.c
+++ b/src/xcb_out.c
@@ -126,8 +126,7 @@ int XCBSendRequest(XCBConnection *c, unsigned int *request, int flags, struct io
         ((CARD16 *) vector[0].iov_base)[1] = shortlen;
         if(!shortlen)
         {
-            memmove(vector + 1, vector, veclen++ * sizeof(*vector));
-            ++veclen;
+            --vector, ++veclen;
             vector[0].iov_base = prefix;
             vector[0].iov_len = sizeof(prefix);
             prefix[0] = ((CARD32 *) vector[0].iov_base)[0];
@@ -237,12 +236,14 @@ int _xcb_out_write_block(XCBConnection *c, struct iovec *vector, size_t count)
     {
         memcpy(c->out.queue + c->out.queue_len, vector[0].iov_base, vector[0].iov_len);
         c->out.queue_len += vector[0].iov_len;
+        vector[0].iov_base = (char *) vector[0].iov_base + vector[0].iov_len;
+        vector[0].iov_len = 0;
         ++vector, --count;
     }
     if(!count)
         return 1;
 
-    memmove(vector + 1, vector, count++ * sizeof(struct iovec));
+    --vector, ++count;
     vector[0].iov_base = c->out.queue;
     vector[0].iov_len = c->out.queue_len;
     c->out.queue_len = 0;