/* $NetBSD: tty_conf.c,v 1.57 2021/08/09 20:49:10 andvar Exp $ */ /*- * Copyright (c) 2005, 2007 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe. * * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /*- * Copyright (c) 1982, 1986, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * 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. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. * * @(#)tty_conf.c 8.5 (Berkeley) 1/9/95 */ #include <sys/cdefs.h> __KERNEL_RCSID(0, "$NetBSD: tty_conf.c,v 1.57 2021/08/09 20:49:10 andvar Exp $"); #define TTY_ALLOW_PRIVATE #include <sys/param.h> #include <sys/systm.h> #include <sys/poll.h> #include <sys/proc.h> #include <sys/tty.h> #include <sys/ttycom.h> #include <sys/conf.h> #include <sys/mutex.h> #include <sys/queue.h> static struct linesw termios_disc = { .l_name = "termios", .l_open = ttylopen, .l_close = ttylclose, .l_read = ttread, .l_write = ttwrite, .l_ioctl = ttynullioctl, .l_rint = ttyinput, .l_start = ttstart, .l_modem = ttymodem, .l_poll = ttpoll }; /* * This is for the benefit of old BSD TTY compatibility, but since it is * identical to termios (except for the name), don't bother conditionalizing * it. */ static struct linesw ntty_disc = { /* old NTTYDISC */ .l_name = "ntty", .l_open = ttylopen, .l_close = ttylclose, .l_read = ttread, .l_write = ttwrite, .l_ioctl = ttynullioctl, .l_rint = ttyinput, .l_start = ttstart, .l_modem = ttymodem, .l_poll = ttpoll }; static LIST_HEAD(, linesw) ttyldisc_list = LIST_HEAD_INITIALIZER(ttyldisc_head); /* * Note: We don't bother refcounting termios_disc and ntty_disc; they can't * be removed from the list, and termios_disc is likely to have very many * references (could we overflow the count?). */ #define TTYLDISC_ISSTATIC(disc) \ ((disc) == &termios_disc || (disc) == &ntty_disc) #define TTYLDISC_HOLD(disc) \ do { \ if (! TTYLDISC_ISSTATIC(disc)) { \ KASSERT((disc)->l_refcnt != UINT_MAX); \ (disc)->l_refcnt++; \ } \ } while (/*CONSTCOND*/0) #define TTYLDISC_RELE(disc) \ do { \ if (! TTYLDISC_ISSTATIC(disc)) { \ KASSERT((disc)->l_refcnt != 0); \ (disc)->l_refcnt--; \ } \ } while (/*CONSTCOND*/0) #define TTYLDISC_ISINUSE(disc) \ (TTYLDISC_ISSTATIC(disc) || (disc)->l_refcnt != 0) /* * Do nothing specific version of line * discipline specific ioctl command. */ /*ARGSUSED*/ int ttynullioctl(struct tty *tp, u_long cmd, void *data, int flags, struct lwp *l) { return (EPASSTHROUGH); } /* * Return error to line discipline * specific poll call. */ /*ARGSUSED*/ int ttyerrpoll(struct tty *tp, int events, struct lwp *l) { return (POLLERR); } void ttyldisc_init(void) { if (ttyldisc_attach(&termios_disc) != 0) panic("ttyldisc_init: termios_disc"); if (ttyldisc_attach(&ntty_disc) != 0) panic("ttyldisc_init: ntty_disc"); } static struct linesw * ttyldisc_lookup_locked(const char *name) { struct linesw *disc; LIST_FOREACH(disc, &ttyldisc_list, l_list) { if (strcmp(name, disc->l_name) == 0) return (disc); } return (NULL); } /* * Look up a line discipline by its name. Caller holds a reference on * the returned line discipline. */ struct linesw * ttyldisc_lookup(const char *name) { struct linesw *disc; mutex_spin_enter(&tty_lock); disc = ttyldisc_lookup_locked(name); if (disc != NULL) TTYLDISC_HOLD(disc); mutex_spin_exit(&tty_lock); return (disc); } /* * Look up a line discipline by its legacy number. Caller holds a * reference on the returned line discipline. */ struct linesw * ttyldisc_lookup_bynum(int num) { struct linesw *disc; mutex_spin_enter(&tty_lock); LIST_FOREACH(disc, &ttyldisc_list, l_list) { if (disc->l_no == num) { TTYLDISC_HOLD(disc); mutex_spin_exit(&tty_lock); return (disc); } } mutex_spin_exit(&tty_lock); return (NULL); } /* * Release a reference on a line discipline previously added by * ttyldisc_lookup() or ttyldisc_lookup_bynum(). */ void ttyldisc_release(struct linesw *disc) { if (disc == NULL) return; mutex_spin_enter(&tty_lock); TTYLDISC_RELE(disc); mutex_spin_exit(&tty_lock); } #define TTYLDISC_LEGACY_NUMBER_MIN 10 #define TTYLDISC_LEGACY_NUMBER_MAX INT_MAX static void ttyldisc_assign_legacy_number(struct linesw *disc) { static const struct { const char *name; int num; } table[] = { { "termios", TTYDISC }, { "ntty", 2 /* XXX old NTTYDISC */ }, { "tablet", TABLDISC }, { "slip", SLIPDISC }, { "ppp", PPPDISC }, { "strip", STRIPDISC }, { "hdlc", HDLCDISC }, { NULL, 0 } }; struct linesw *ldisc; int i; for (i = 0; table[i].name != NULL; i++) { if (strcmp(disc->l_name, table[i].name) == 0) { disc->l_no = table[i].num; return; } } disc->l_no = TTYLDISC_LEGACY_NUMBER_MIN; LIST_FOREACH(ldisc, &ttyldisc_list, l_list) { if (disc->l_no == ldisc->l_no) { KASSERT(disc->l_no < TTYLDISC_LEGACY_NUMBER_MAX); disc->l_no++; } } } /* * Register a line discipline. */ int ttyldisc_attach(struct linesw *disc) { KASSERT(disc->l_name != NULL); KASSERT(disc->l_open != NULL); KASSERT(disc->l_close != NULL); KASSERT(disc->l_read != NULL); KASSERT(disc->l_write != NULL); KASSERT(disc->l_ioctl != NULL); KASSERT(disc->l_rint != NULL); KASSERT(disc->l_start != NULL); KASSERT(disc->l_modem != NULL); KASSERT(disc->l_poll != NULL); /* You are not allowed to exceed TTLINEDNAMELEN */ if (strlen(disc->l_name) >= TTLINEDNAMELEN) return (ENAMETOOLONG); mutex_spin_enter(&tty_lock); if (ttyldisc_lookup_locked(disc->l_name) != NULL) { mutex_spin_exit(&tty_lock); return (EEXIST); } ttyldisc_assign_legacy_number(disc); LIST_INSERT_HEAD(&ttyldisc_list, disc, l_list); mutex_spin_exit(&tty_lock); return (0); } /* * Remove a line discipline. */ int ttyldisc_detach(struct linesw *disc) { #ifdef DIAGNOSTIC struct linesw *ldisc = ttyldisc_lookup(disc->l_name); KASSERT(ldisc != NULL); KASSERT(ldisc == disc); ttyldisc_release(ldisc); #endif mutex_spin_enter(&tty_lock); if (TTYLDISC_ISINUSE(disc)) { mutex_spin_exit(&tty_lock); return (EBUSY); } LIST_REMOVE(disc, l_list); mutex_spin_exit(&tty_lock); return (0); } /* * Return the default line discipline. */ struct linesw * ttyldisc_default(void) { return (&termios_disc); }
