From 9f5d83706543696fc944c1835a403938c06f2cc5 Mon Sep 17 00:00:00 2001
From: Alan Coopersmith <alan.coopersmith@oracle.com>
Date: Sat, 02 Mar 2013 04:54:24 +0000
Subject: Add _XEatDataWords to discard a given number of 32-bit words of reply data

Matches the units of the length field in X protocol replies, and provides
a single implementation of overflow checking to avoid having to replicate
those checks in every caller.

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Matthieu Herrb <matthieu.herrb@laas.fr>

Upstream-Status: Backport
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

---
diff --git a/include/X11/Xlibint.h b/include/X11/Xlibint.h
index 06395b3..d63a534 100644
--- a/include/X11/Xlibint.h
+++ b/include/X11/Xlibint.h
@@ -855,6 +855,10 @@ extern void _XEatData(
     Display*		/* dpy */,
     unsigned long	/* n */
 );
+extern void _XEatDataWords(
+    Display*		/* dpy */,
+    unsigned long	/* n */
+);
 extern char *_XAllocScratch(
     Display*		/* dpy */,
     unsigned long	/* nbytes */
diff --git a/src/xcb_io.c b/src/xcb_io.c
index 300ef57..727c6c7 100644
--- a/src/xcb_io.c
+++ b/src/xcb_io.c
@@ -19,6 +19,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <limits.h>
 #ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
 #endif
@@ -757,3 +758,19 @@ void _XEatData(Display *dpy, unsigned long n)
 	dpy->xcb->reply_consumed += n;
 	_XFreeReplyData(dpy, False);
 }
+
+/*
+ * Read and discard "n" 32-bit words of data
+ * Matches the units of the length field in X protocol replies, and provides
+ * a single implementation of overflow checking to avoid having to replicate
+ * those checks in every caller.
+ */
+void _XEatDataWords(Display *dpy, unsigned long n)
+{
+	if (n < ((INT_MAX - dpy->xcb->reply_consumed) >> 2))
+		dpy->xcb->reply_consumed += (n << 2);
+	else
+		/* Overflow would happen, so just eat the rest of the reply */
+		dpy->xcb->reply_consumed = dpy->xcb->reply_length;
+	_XFreeReplyData(dpy, False);
+}
--
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