[PATCH] Fix XNextRequest() after direct usage of XCB

[otaylor at redhat.com]

From: "Owen W. Taylor" <otaylor at fishsoup.net>

When XCB owns the X socket, dpy->request is not updated, so
NextRequest() and XNextRequest() return the wrong value. There's
nothing we can do to fix NextRequest() while retaining ABI compat,
but change XNextRequest() to grab the socket back from XCB,
updating dpy->request.

Signed-off-by: Owen W. Taylor <otaylor at fishsoup.net>
---
 src/Macros.c  | 12 ++++++++++++
 src/Xxcbint.h |  2 ++
 src/xcb_io.c  | 11 +++++++++++
 3 files changed, 25 insertions(+)

diff --git a/src/Macros.c b/src/Macros.c
index cfc083a..b57f577 100644
--- a/src/Macros.c
+++ b/src/Macros.c
@@ -30,6 +30,7 @@ in this Software without prior written authorization from The Open Group.
 #include "Xlibint.h"
 #define XUTIL_DEFINE_FUNCTIONS
 #include "Xutil.h"
+#include "Xxcbint.h"
 
 /*
  * This file makes full definitions of routines for each macro.
@@ -135,8 +136,19 @@ int XBitmapPad(Display *dpy) { return (BitmapPad(dpy)); }
 
 int XImageByteOrder(Display *dpy) { return (ImageByteOrder(dpy)); }
 
+/* XNextRequest() differs from the rest of the functions here because it is
+ * no longer a Macro wrapper - when libX11 is being used mixed together
+ * with direct use of xcb, the next request field of the Display structure will
+ * not be updated; we can't fix the NextRequest() macro in any easy way,
+ * but we can at least make XNextRequest() do the right thing.
+ */
 unsigned long XNextRequest(Display *dpy)
 {
+    unsigned long next_request;
+    LockDisplay(dpy);
+    next_request = _XNextRequest(dpy);
+    UnlockDisplay(dpy);
+
     return (NextRequest(dpy));
 }
 
diff --git a/src/Xxcbint.h b/src/Xxcbint.h
index a8c9a67..bf41c23 100644
--- a/src/Xxcbint.h
+++ b/src/Xxcbint.h
@@ -46,4 +46,6 @@ typedef struct _X11XCBPrivate {
 int _XConnectXCB(Display *dpy, _Xconst char *display, int *screenp);
 void _XFreeX11XCBStructure(Display *dpy);
 
+unsigned long _XNextRequest(Display *dpy);
+
 #endif /* XXCBINT_H */
diff --git a/src/xcb_io.c b/src/xcb_io.c
index 727c6c7..5987329 100644
--- a/src/xcb_io.c
+++ b/src/xcb_io.c
@@ -774,3 +774,14 @@ void _XEatDataWords(Display *dpy, unsigned long n)
 		dpy->xcb->reply_consumed = dpy->xcb->reply_length;
 	_XFreeReplyData(dpy, False);
 }
+
+unsigned long
+_XNextRequest(Display *dpy)
+{
+    /* This will update dpy->request. The assumption is that the next thing
+     * that the application will do is make a request so there's little
+     * overhead.
+     */
+    require_socket(dpy);
+    return NextRequest(dpy);
+}
-- 
1.9.0