From 1fbe5348a32bb40b9e3cd26ab168233d2c59f274 Mon Sep 17 00:00:00 2001
From: Andreas Eriksson <andreas@eriksson.cc>
Date: Wed, 6 May 2015 20:36:37 +0200
Subject: [PATCH] Change libswmhack.so to use RTLD_NEXT functionality when
 _GNU_SOURCE is defined, and add some error handling.

---
 lib/swm_hack.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 6 deletions(-)

diff --git a/lib/swm_hack.c b/lib/swm_hack.c
index c5f5b5b..40fa224 100644
--- a/lib/swm_hack.c
+++ b/lib/swm_hack.c
@@ -95,13 +95,26 @@ set_property(Display *dpy, Window id, char *name, char *val)
 	static XIA		*xia = NULL;
 	static XCP		*xcp = NULL;
 
+#ifdef _GNU_SOURCE
+	/* load the function pointer with RTLD_NEXT
+	 * this might be the real X function or another
+	 * preloaded intercept
+	 */
+	if (!lib_xlib)
+		lib_xlib = RTLD_NEXT;
+#else
 	/* find the real Xlib and the real X function */
 	if (!lib_xlib)
 		lib_xlib = dlopen("libX11.so", RTLD_GLOBAL | RTLD_LAZY);
-	if (!xia)
+#endif
+	if (lib_xlib && !xia)
 		xia = (XIA *) dlsym(lib_xlib, "XInternAtom");
-	if (!xcp)
+	if (lib_xlib && !xcp)
 		xcp = (XCP *) dlsym(lib_xlib, "XChangeProperty");
+	if (!xia || !xcp) {
+		fprintf(stderr, "libswmhack.so: ERROR: %s\n", dlerror());
+		return;
+	}
 
 	/* Try to update the window's workspace property */
 	atom = (*xia)(dpy, name, False);
@@ -132,13 +145,26 @@ XCreateWindow(Display *dpy, Window parent, int x, int y,
 	char		*env;
 	Window		id;
 
+#ifdef _GNU_SOURCE
+	/* load the function pointer with RTLD_NEXT
+	 * this might be the real X function or another
+	 * preloaded intercept
+	 */
+	if (!lib_xlib)
+		lib_xlib = RTLD_NEXT;
+#else
 	/* find the real Xlib and the real X function */
 	if (!lib_xlib)
 		lib_xlib = dlopen("libX11.so", RTLD_GLOBAL | RTLD_LAZY);
-	if (!func) {
+#endif
+	if (lib_xlib && !func) {
 		func = (CWF *) dlsym(lib_xlib, "XCreateWindow");
 		display = dpy;
 	}
+	if (!func) {
+		fprintf(stderr, "libswmhack.so: ERROR: %s\n", dlerror());
+		return BadImplementation;
+	}
 
 	if (parent == DefaultRootWindow(dpy))
 		parent = MyRoot(dpy);
@@ -177,11 +203,24 @@ XCreateSimpleWindow(Display *dpy, Window parent, int x, int y,
 	char		*env;
 	Window		id;
 
+#ifdef _GNU_SOURCE
+	/* load the function pointer with RTLD_NEXT
+	 * this might be the real X function or another
+	 * preloaded intercept
+	 */
+	if (!lib_xlib)
+		lib_xlib = RTLD_NEXT;
+#else
 	/* find the real Xlib and the real X function */
 	if (!lib_xlib)
 		lib_xlib = dlopen("libX11.so", RTLD_GLOBAL | RTLD_LAZY);
-	if (!func)
+#endif
+	if (lib_xlib && !func)
 		func = (CSWF *) dlsym(lib_xlib, "XCreateSimpleWindow");
+	if (!func) {
+		fprintf(stderr, "libswmhack.so: ERROR: %s\n", dlerror());
+		return BadImplementation;
+	}
 
 	if (parent == DefaultRootWindow(dpy))
 		parent = MyRoot(dpy);
@@ -211,11 +250,24 @@ XReparentWindow(Display *dpy, Window window, Window parent, int x, int y)
 {
 	static RWF         *func = NULL;
 
+#ifdef _GNU_SOURCE
+	/* load the function pointer with RTLD_NEXT
+	 * this might be the real X function or another
+	 * preloaded intercept
+	 */
+	if (!lib_xlib)
+		lib_xlib = RTLD_NEXT;
+#else
 	/* find the real Xlib and the real X function */
 	if (!lib_xlib)
 		lib_xlib = dlopen("libX11.so", RTLD_GLOBAL | RTLD_LAZY);
-	if (!func)
+#endif
+	if (lib_xlib && !func)
 		func = (RWF *) dlsym(lib_xlib, "XReparentWindow");
+	if (!func) {
+		fprintf(stderr, "libswmhack.so: ERROR: %s\n", dlerror());
+		return BadImplementation;
+	}
 
 	if (parent == DefaultRootWindow(dpy))
 		parent = MyRoot(dpy);
@@ -238,16 +290,29 @@ XtAppNextEvent(XtAppContext app_context, XEvent *event_return)
 	static ANEF	*func = NULL;
 	static KeyCode	kp_add = 0, kp_subtract = 0;
 
+#ifdef _GNU_SOURCE
+	/* load the function pointer with RTLD_NEXT
+	 * this might be the real X function or another
+	 * preloaded intercept
+	 */
+	if (!lib_xtlib)
+		lib_xtlib = RTLD_NEXT;
+#else
 	/* find the real Xlib and the real X function */
 	if (!lib_xtlib)
 		lib_xtlib = dlopen("libXt.so", RTLD_GLOBAL | RTLD_LAZY);
-	if (!func) {
+#endif
+	if (lib_xtlib && !func) {
 		func = (ANEF *) dlsym(lib_xtlib, "XtAppNextEvent");
 		if (display != NULL) {
 			kp_add = XKeysymToKeycode(display, XK_KP_Add);
 			kp_subtract = XKeysymToKeycode(display, XK_KP_Subtract);
 		}
 	}
+	if (!func) {
+		fprintf(stderr, "libswmhack.so: ERROR: %s\n", dlerror());
+		return;
+	}
 
 	(*func) (app_context, event_return);
 
-- 
2.39.2