super-fast magic sysrq shutdown

1 files changed, 26 insertions, 7 deletions

diff --git a/instr-daemon.c b/instr-daemon.c
index 24c6132..da396bc 100644
--- a/instr-daemon.c
+++ b/instr-daemon.c
@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <ctype.h>
 #include <glib.h>
+#include <fcntl.h>
 
 #define STDIN_BUF_SIZE 1024
 
@@ -315,7 +316,25 @@ int main(int argc, char **argv)
 static gboolean periodic_poll (void)
 {
 	if (bus_getpin (POWER_FAIL)) {
-		system ("/usr/bin/systemctl poweroff");
+
+		LCD_clear();
+		LCD_write(0,0,"Power failed. Shutdown.");
+
+		// use plain old open to avoid any buffering etc
+		int enablefd = open("/proc/sys/kernel/sysrq", O_SYNC, O_RDWR);
+		int trgfd = open("/proc/sysrq-trigger", O_SYNC, O_RDWR);
+
+		// enable sysrq
+		write(enablefd, "1\n", 2);
+
+		// remount ro
+		write(trgfd, "u\n", 2);
+
+		// sync disks
+		write(trgfd, "s\n", 2);
+
+		// poweroff
+		system ("/usr/bin/systemctl poweroff -f");	
 	}
 
 	Menu_Check_Buttons ();
@@ -326,12 +345,12 @@ static gboolean periodic_poll (void)
 	// is crashing due to non-functional bus
 	GPIB_check_for_device_clear_signal();
 	if (GPIB_check_for_messages(globals.Registers.gpib_buffer)) {
-               if (GPIB_handle_new_input(globals.Registers.gpib_buffer)) {
-               // FIXME check_for_ctrl_mode_changes();
-        	        Parser_main(globals.Registers.gpib_buffer, 0, NULL, NULL);
-            	}
-        }
-        GPIB_check_for_device_clear_signal();
+		if (GPIB_handle_new_input(globals.Registers.gpib_buffer)) {
+			// FIXME check_for_ctrl_mode_changes();
+			Parser_main(globals.Registers.gpib_buffer, 0, NULL, NULL);
+		}
+	}
+	GPIB_check_for_device_clear_signal();
 
 	return TRUE;
 }