Convert this driver to (ab?)use line disciplines to get the input it

needs instead of relying on idiosyncratic hacks in the tty subsystem.
Also add module code since this can now be compiled as a module.

Silence by:	-hackers, -audit

1 files changed, 84 insertions, 17 deletions

diff --git a/sys/kern/tty_snoop.c b/sys/kern/tty_snoop.c
index 8560928..8019418 100644
--- a/sys/kern/tty_snoop.c
+++ b/sys/kern/tty_snoop.c
@@ -15,7 +15,6 @@
  * $FreeBSD$
  */
 
-#include "opt_compat.h"
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/filio.h>
@@ -29,6 +28,7 @@
 #include <sys/kernel.h>
 #include <sys/snoop.h>
 #include <sys/vnode.h>
+#include <sys/conf.h>
 
 static	d_open_t	snpopen;
 static	d_close_t	snpclose;
@@ -61,9 +61,63 @@ static struct cdevsw snp_cdevsw = {
 
 static MALLOC_DEFINE(M_SNP, "snp", "Snoop device data");
 
+#define ttytosnp(t) (struct snoop *)(t)->t_sc
 static struct tty	*snpdevtotty __P((dev_t dev));
 static int		snp_detach __P((struct snoop *snp));
 
+/*
+ * The number of the "snoop" line discipline.  This gets determined at
+ * module load time.
+ */
+static int mylinedisc;
+
+static int
+dsnwrite(struct tty *tp, struct uio *uio, int flag)
+{
+	struct snoop *snp = ttytosnp(tp);
+	int error = 0;
+	char ibuf[1024];
+	int ilen;
+	struct iovec iov;
+	struct uio uio2;
+
+	while (uio->uio_resid) {
+		ilen = MIN(sizeof(ibuf), uio->uio_resid);
+		error = uiomove(ibuf, ilen, uio);
+		if (error)
+			break;
+		snpin(snp, ibuf, ilen);
+		/* Hackish, but I think it's the least of all evils. */
+		iov.iov_base = ibuf;
+		iov.iov_len = ilen;
+		uio2.uio_iov = &iov;
+		uio2.uio_iovcnt = 1;
+		uio2.uio_offset = 0;
+		uio2.uio_resid = ilen;
+		uio2.uio_segflg = UIO_SYSSPACE;
+		uio2.uio_rw = UIO_WRITE;
+		uio2.uio_procp = uio->uio_procp;
+		error = ttwrite(tp, &uio2, flag);
+		if (error)
+			break;
+	}
+	return (error);
+}
+
+/*
+ * XXX should there be a global version of this?
+ */
+static int
+l_nullioctl(struct tty *tp, u_long cmd, char *data, int flags, struct proc *p)
+{
+
+	return (ENOIOCTL);
+}
+
+static struct linesw snpdisc = {
+	ttyopen,	ttylclose,	ttread,		dsnwrite,
+	l_nullioctl,	ttyinput,	ttstart,	ttymodem };
+
 static struct tty *
 snpdevtotty (dev)
 	dev_t		dev;
@@ -98,7 +152,7 @@ snpwrite(dev, uio, flag)
 	tp = snp->snp_tty;
 
 	if ((tp->t_sc == snp) && (tp->t_state & TS_SNOOP) &&
-	    (tp->t_line == OTTYDISC || tp->t_line == NTTYDISC))
+	    tp->t_line == mylinedisc)
 		goto tty_input;
 
 	printf("Snoop: attempt to write to bad tty.\n");
@@ -334,9 +388,10 @@ snp_detach(snp)
 	tp = snp->snp_tty;
 
 	if (tp && (tp->t_sc == snp) && (tp->t_state & TS_SNOOP) &&
-	    (tp->t_line == OTTYDISC || tp->t_line == NTTYDISC)) {
+	    tp->t_line == mylinedisc) {
 		tp->t_sc = NULL;
 		tp->t_state &= ~TS_SNOOP;
+		tp->t_line = snp->snp_olddisc;
 	} else
 		printf("Snoop: bad attached tty data.\n");
 
@@ -409,12 +464,6 @@ snpioctl(dev, cmd, data, flags, p)
 		if (!tp)
 			return (EINVAL);
 
-		if ((tp->t_sc != (caddr_t)snp) && (tp->t_state & TS_SNOOP))
-			return (EBUSY);
-
-		if ((tp->t_line != OTTYDISC) && (tp->t_line != NTTYDISC))
-			return (EBUSY);
-
 		s = spltty();
 
 		if (snp->snp_target == NODEV) {
@@ -425,6 +474,8 @@ snpioctl(dev, cmd, data, flags, p)
 
 		tp->t_sc = (caddr_t)snp;
 		tp->t_state |= TS_SNOOP;
+		snp->snp_olddisc = tp->t_line;
+		tp->t_line = mylinedisc;
 		snp->snp_tty = tp;
 		snp->snp_target = tdev;
 
@@ -503,8 +554,6 @@ snppoll(dev, events, p)
 	return (revents);
 }
 
-static void snp_drvinit __P((void *unused));
-
 static void
 snp_clone(void *arg, char *name, int namelen, dev_t *dev)
 {
@@ -519,13 +568,31 @@ snp_clone(void *arg, char *name, int namelen, dev_t *dev)
 	return;
 }
 
-static void
-snp_drvinit(unused)
-	void *unused;
+static int
+snp_modevent(module_t mod, int type, void *data)
 {
+	static eventhandler_tag eh_tag = NULL;
 
-	EVENTHANDLER_REGISTER(dev_clone, snp_clone, 0, 1000);
-	cdevsw_add(&snp_cdevsw);
+	switch (type) {
+	case MOD_LOAD:
+		eh_tag = EVENTHANDLER_REGISTER(dev_clone, snp_clone, 0, 1000);
+		mylinedisc = ldisc_register(LDISC_LOAD, &snpdisc);
+		cdevsw_add(&snp_cdevsw);
+		break;
+	case MOD_UNLOAD:
+		EVENTHANDLER_DEREGISTER(dev_clone, eh_tag);
+		ldisc_deregister(mylinedisc);
+		cdevsw_remove(&snp_cdevsw);
+		break;
+	default:
+		break;
+	}
+	return 0;
 }
 
-SYSINIT(snpdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,snp_drvinit,NULL)
+static moduledata_t snp_mod = {
+        "snp",
+        snp_modevent,
+        NULL
+};
+DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE+CDEV_MAJOR);