Test the availability of SA_RESTART and use it conditionally.

ChangeLog

@@ -11,6 +11,7 @@ v.0.5dev (ongoing development)
  * Make all drivers using parallel port fail if they cannot get IO permission
  * Include <errno.h> instead of <sys/errno.h> everywhere (found by S. Klauer)
  * configure: Fix de-selecting of drivers
+ * Build system: Add a check testing if SA_RESTART flag is available.
 
 v0.5.3
  + lcdexec: notification when called program finishes

acinclude.m4

@@ -884,6 +884,7 @@ AC_SUBST(enable_latex_dox)
 ])
 
 
+dnl Check if a given flag is understood and add it to CFLAGS.
 dnl From: http://autoconf-archive.cryp.to/ax_cflags_gcc_option.html
 dnl Author: Guido Draheim <guidod@gmx.de>
 dnl Last Modified: 2003-11-04
@@ -1029,3 +1030,17 @@ AC_DEFUN([AX_CFLAGS_GCC_OPTION],[ifelse(m4_bregexp([$2],[-]),-1,
 AC_DEFUN([AX_CXXFLAGS_GCC_OPTION],[ifelse(m4_bregexp([$2],[-]),-1,
 [AX_CXXFLAGS_GCC_OPTION_NEW($@)],[AX_CXXFLAGS_GCC_OPTION_OLD($@)])])
 
+dnl
+dnl Check if system has SA_RESTART defined. Copied from GNU's make configure.
+dnl
+AC_DEFUN([LCD_SA_RESTART], [
+AC_CACHE_CHECK([for SA_RESTART], lcd_cv_sa_restart, [
+  AC_TRY_COMPILE([#include <signal.h>],
+      [return SA_RESTART;],
+      lcd_cv_sa_restart=yes,
+      lcd_cv_sa_restart=no)])
+if test "$lcd_cv_sa_restart" != no; then
+  AC_DEFINE([HAVE_SA_RESTART], [1],
+     [Define to 1 if <signal.h> defines the SA_RESTART constant.])
+fi
+])

clients/lcdexec/lcdexec.c

@@ -157,7 +157,9 @@ int main(int argc, char **argv)
 
 	/* setup signal handlers for common signals */
 	sigemptyset(&sa.sa_mask);
+#ifdef HAVE_SA_RESTART
 	sa.sa_flags = SA_RESTART;
+#endif
 	sa.sa_handler = exit_program;
 	sigaction(SIGINT, &sa, NULL);	// Ctrl-C
 	sigaction(SIGTERM, &sa, NULL);	// "regular" kill

clients/lcdvc/lcdvc.c

@@ -120,7 +120,9 @@ int main(int argc, char **argv)
 
 	/* setup signal handlers for common signals */
 	sigemptyset(&sa.sa_mask);
+#ifdef HAVE_SA_RESTART
 	sa.sa_flags = SA_RESTART;
+#endif
 	sa.sa_handler = exit_program;
 	sigaction(SIGINT, &sa, NULL);	// Ctrl-C
 	sigaction(SIGTERM, &sa, NULL);	// "regular" kill

configure.in

@@ -174,6 +174,7 @@ AC_CHECK_HEADERS([sys/sysctl.h], [], [],
 ]])
 
 dnl Check for particular preprocessor macros
+LCD_SA_RESTART
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST

server/main.c

@@ -559,7 +559,9 @@ install_signal_handlers(int allow_reload)
 	sigaction(SIGPIPE, &sa, NULL);
 
 	sa.sa_handler = exit_program;
+#ifdef HAVE_SA_RESTART
 	sa.sa_flags = SA_RESTART;
+#endif
 
 	sigaction(SIGINT, &sa, NULL);		/* Ctrl-C will cause a clean exit...*/
 	sigaction(SIGTERM, &sa, NULL);		/* and "kill"...*/