use sysrq to do an emergency shutdown

1 files changed, 16 insertions, 2 deletions

diff --git a/instr-daemon.c b/instr-daemon.c
index 5f764ed..40a65b2 100644
--- a/instr-daemon.c
+++ b/instr-daemon.c
@@ -15,6 +15,7 @@
 #include <ctype.h>
 #include <glib.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 #define STDIN_BUF_SIZE 1024
 
@@ -316,8 +317,21 @@ int main(int argc, char **argv)
 static gboolean periodic_poll (void)
 {
 	if (bus_getpin (POWER_FAIL)) {
-		sync();
-		system ("/usr/bin/systemctl poweroff");
+		//system ("/usr/bin/systemctl poweroff");
+
+		// 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);
+
 	}
 
 	Menu_Check_Buttons ();