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-rw-r--r--toys/Config.in16
-rw-r--r--toys/oneit.c45
-rw-r--r--toys/toylist.h1
3 files changed, 62 insertions, 0 deletions
diff --git a/toys/Config.in b/toys/Config.in
index 77e59e4d..59271ddb 100644
--- a/toys/Config.in
+++ b/toys/Config.in
@@ -34,6 +34,22 @@ config HELLO
help
A hello world program. You don't need this.
+config ONEIT
+ bool "oneit"
+ default n
+ help
+ usage: oneit [-p] command [...]
+
+ A simple init program that runs a single supplied command line with a
+ controlling tty (so CTRL-C can kill it).
+
+ -p Power off instead of rebooting when command exits.
+
+ The oneit command runs the supplied command line as a child process
+ (because PID 1 has signals blocked), attached to /dev/tty0, in its
+ own session. Then oneit reaps zombies until the child exits, at
+ which point it reboots (or with -p, powers off) the system.
+
config PWD
bool "pwd"
default n
diff --git a/toys/oneit.c b/toys/oneit.c
new file mode 100644
index 00000000..1f87e5f2
--- /dev/null
+++ b/toys/oneit.c
@@ -0,0 +1,45 @@
+/* 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);
+}
diff --git a/toys/toylist.h b/toys/toylist.h
index a61aff93..ef427491 100644
--- a/toys/toylist.h
+++ b/toys/toylist.h
@@ -57,6 +57,7 @@ USE_TOYSH(NEWTOY(cd, NULL, TOYFLAG_NOFORK))
USE_DF(NEWTOY(df, "Pkt*a", TOYFLAG_USR|TOYFLAG_SBIN))
USE_TOYSH(NEWTOY(exit, NULL, TOYFLAG_NOFORK))
USE_HELLO(NEWTOY(hello, NULL, TOYFLAG_NOFORK|TOYFLAG_USR))
+USE_ONEIT(NEWTOY(oneit, "+p<1", TOYFLAG_SBIN))
USE_PWD(NEWTOY(pwd, NULL, TOYFLAG_BIN))
USE_TOYSH(OLDTOY(sh, toysh, "c:i", TOYFLAG_BIN))
USE_TOYSH(NEWTOY(toysh, "c:i", TOYFLAG_BIN))