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+/* oneit.c, tiny one-process init replacement.
+ *
+ * Copyright 2005 by Rob Landley <rob@landley.net>.
+ */
+
+#include "toys.h"
+#include <sys/reboot.h>
+
+// The minimum amount of work necessary to get ctrl-c and such to work is:
+//
+// - Fork a child (PID 1 is special: can't exit, has various signals blocked).
+// - Do a setsid() (so we have our own session).
+// - In the child, attach stdio to /dev/tty0 (/dev/console is special)
+// - Exec the rest of the command line.
+//
+// PID 1 then reaps zombies until the child process it spawned exits, at which
+// point it calls sync() and reboot(). I could stick a kill -1 in there.
+
+int oneit_main(void)
+{
+ int i;
+ pid_t pid;
+
+ // Create a new child process.
+ pid = vfork();
+ if (pid) {
+
+ // pid 1 just reaps zombies until it gets its child, then halts the system.
+ while (pid!=wait(&i));
+ sync();
+ reboot(toys.optflags ? RB_POWER_OFF : RB_AUTOBOOT);
+ }
+
+ // Redirect stdio to /dev/tty0, with new session ID, so ctrl-c works.
+ setsid();
+ for (i=0; i<3; i++) {
+ close(i);
+ open("/dev/tty0",O_RDWR);
+ }
+
+ // Can't xexec() here because we vforked so we don't want to error_exit().
+ toy_exec(toys.optargs);
+ execvp(*toys.optargs, toys.optargs);
+ _exit(127);
+}