Use RTLD_DI_SETSIGNAL to catch runtime dynamic loader errors and clean up

Based on fix for Sun bug 6813925: Xorg needs to catch ld.so.1 failure
 so it can close down devices cleanly
<http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6813925>

Signed-off-by: Alan Coopersmith <alan.coopersmith@sun.com>

configure.ac

@@ -105,7 +105,7 @@ AM_CONDITIONAL(XSERVER_DTRACE, [test "x$WDTRACE" != "xno"])
 
 AC_HEADER_DIRENT
 AC_HEADER_STDC
-AC_CHECK_HEADERS([fcntl.h stdlib.h string.h unistd.h])
+AC_CHECK_HEADERS([fcntl.h stdlib.h string.h unistd.h dlfcn.h])
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST

os/osinit.c

@@ -56,6 +56,9 @@ SOFTWARE.
 #include <X11/Xos.h>
 #include <signal.h>
 #include <errno.h>
+#ifdef HAVE_DLFCN_H
+# include <dlfcn.h>
+#endif
 
 #include "dixstruct.h"
 
@@ -113,6 +116,14 @@ OsSigHandler(int signo, siginfo_t *sip, void *unused)
 OsSigHandler(int signo)
 #endif
 {
+#ifdef RTLD_DI_SETSIGNAL
+  const char *dlerr = dlerror();
+
+  if (dlerr) {
+      LogMessage(X_ERROR, "Dynamic loader error: %s\n", dlerr);
+  }
+#endif /* RTLD_DI_SETSIGNAL */
+
   if (OsSigWrapper != NULL) {
       if (OsSigWrapper(signo) == 0) {
 	  /* ddx handled signal and wants us to continue */
@@ -180,6 +191,15 @@ OsInit(void)
 	    }
 	}
 
+#ifdef RTLD_DI_SETSIGNAL
+	/* Tell runtime linker to send a signal we can catch instead of SIGKILL
+	 * for failures to load libraries/modules at runtime so we can clean up
+	 * after ourselves.
+	 */
+	int failure_signal = SIGQUIT;
+	dlinfo(RTLD_SELF, RTLD_DI_SETSIGNAL, &failure_signal);
+#endif
+
 #if !defined(__SCO__) && !defined(__CYGWIN__) && !defined(__UNIXWARE__)
 	fclose(stdin);
 	fclose(stdout);