From 3d8e6186e2a82569f4f5214f8c8af700e5e36c13 Mon Sep 17 00:00:00 2001
From: ed <ed@FreeBSD.org>
Date: Sun, 23 Aug 2009 20:26:09 +0000
Subject: Allow pty(4) to be loaded as a kld.

Unfortunately, the wrappers that are present in pts(4) don't have the
mechanics to allow pty(4) to be unloaded safely, so I'm forcing this kld
to return EBUSY. This also means we have to enable some extra code in
pts(4) unconditionally.

Proposed by:	rwatson
---
 sys/dev/pty/pty.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 sys/dev/pty/pty.c

(limited to 'sys/dev/pty')

diff --git a/sys/dev/pty/pty.c b/sys/dev/pty/pty.c
new file mode 100644
index 0000000..d3dce9f
--- /dev/null
+++ b/sys/dev/pty/pty.c
@@ -0,0 +1,141 @@
+/*-
+ * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Portions of this software were developed under sponsorship from Snow
+ * B.V., the Netherlands.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/conf.h>
+#include <sys/eventhandler.h>
+#include <sys/fcntl.h>
+#include <sys/kernel.h>
+#include <sys/module.h>
+#include <sys/proc.h>
+#include <sys/sysctl.h>
+#include <sys/syslog.h>
+#include <sys/systm.h>
+#include <sys/tty.h>
+
+/*
+ * This driver implements a BSD-style compatibility naming scheme for
+ * the pts(4) driver. We just call into pts(4) to create the actual PTY.
+ * To make sure we don't use the same PTY multiple times, we abuse
+ * si_drv1 inside the cdev to mark whether the PTY is in use.
+ */
+
+static unsigned int pty_warningcnt = 1;
+SYSCTL_UINT(_kern, OID_AUTO, tty_pty_warningcnt, CTLFLAG_RW,
+	&pty_warningcnt, 0,
+	"Warnings that will be triggered upon legacy PTY allocation");
+
+static int
+ptydev_fdopen(struct cdev *dev, int fflags, struct thread *td, struct file *fp)
+{
+	int error;
+	char name[6]; /* "ttyXX" */
+
+	if (!atomic_cmpset_ptr((uintptr_t *)&dev->si_drv1, 0, 1))
+		return (EBUSY);
+
+	/* Generate device name and create PTY. */
+	strcpy(name, devtoname(dev));
+	name[0] = 't';
+
+	error = pts_alloc_external(fflags & (FREAD|FWRITE), td, fp, dev, name);
+	if (error != 0) {
+		destroy_dev_sched(dev);
+		return (error);
+	}
+
+	/* Raise a warning when a legacy PTY has been allocated. */
+	if (pty_warningcnt > 0) {
+		pty_warningcnt--;
+		log(LOG_INFO, "pid %d (%s) is using legacy pty devices%s\n", 
+		    td->td_proc->p_pid, td->td_name,
+		    pty_warningcnt ? "" : " - not logging anymore");
+	}
+
+	return (0);
+}
+
+static struct cdevsw ptydev_cdevsw = {
+	.d_version	= D_VERSION,
+	.d_fdopen	= ptydev_fdopen,
+	.d_name		= "ptydev",
+};
+
+static void
+pty_clone(void *arg, struct ucred *cr, char *name, int namelen,
+    struct cdev **dev)
+{
+
+	/* Cloning is already satisfied. */
+	if (*dev != NULL)
+		return;
+
+	/* Only catch /dev/ptyXX. */
+	if (namelen != 5 || bcmp(name, "pty", 3) != 0)
+		return;
+
+	/* Only catch /dev/pty[l-sL-S]X. */
+	if (!(name[3] >= 'l' && name[3] <= 's') &&
+	    !(name[3] >= 'L' && name[3] <= 'S'))
+		return;
+
+	/* Only catch /dev/pty[l-sL-S][0-9a-v]. */
+	if (!(name[4] >= '0' && name[4] <= '9') &&
+	    !(name[4] >= 'a' && name[4] <= 'v'))
+		return;
+
+	/* Create the controller device node. */
+	*dev = make_dev_credf(MAKEDEV_REF, &ptydev_cdevsw, 0,
+	    NULL, UID_ROOT, GID_WHEEL, 0666, "%s", name);
+}
+
+static int
+pty_modevent(module_t mod, int type, void *data)
+{
+
+        switch(type) {
+        case MOD_LOAD: 
+		EVENTHANDLER_REGISTER(dev_clone, pty_clone, 0, 1000);
+		break;
+	case MOD_SHUTDOWN:
+		break;
+	case MOD_UNLOAD:
+		/* XXX: No unloading support yet. */
+		return (EBUSY);
+	default:
+		return (EOPNOTSUPP);
+	}
+
+	return (0);
+}
+
+DEV_MODULE(pty, pty_modevent, NULL);
-- 
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