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cons.c revision 1.92 
      1 /*	$NetBSD: cons.c,v 1.92 2022/10/25 23:21:33 riastradh Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988 University of Utah.
      5  * Copyright (c) 1990, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  *
      8  * This code is derived from software contributed to Berkeley by
      9  * the Systems Programming Group of the University of Utah Computer
     10  * Science Department.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  * from: Utah $Hdr: cons.c 1.7 92/01/21$
     37  *
     38  *	@(#)cons.c	8.2 (Berkeley) 1/12/94
     39  */
     40 
     41 #include <sys/cdefs.h>
     42 __KERNEL_RCSID(0, "$NetBSD: cons.c,v 1.92 2022/10/25 23:21:33 riastradh Exp $");
     43 
     44 #include <sys/param.h>
     45 #include <sys/proc.h>
     46 #include <sys/systm.h>
     47 #include <sys/buf.h>
     48 #include <sys/ioctl.h>
     49 #include <sys/poll.h>
     50 #include <sys/tty.h>
     51 #include <sys/file.h>
     52 #include <sys/conf.h>
     53 #include <sys/vnode.h>
     54 #include <sys/kauth.h>
     55 #include <sys/mutex.h>
     56 #include <sys/module.h>
     57 #include <sys/atomic.h>
     58 #include <sys/pserialize.h>
     59 
     60 #include <dev/cons.h>
     61 
     62 #include "nullcons.h"
     63 
     64 dev_type_open(cnopen);
     65 dev_type_close(cnclose);
     66 dev_type_read(cnread);
     67 dev_type_write(cnwrite);
     68 dev_type_ioctl(cnioctl);
     69 dev_type_poll(cnpoll);
     70 dev_type_kqfilter(cnkqfilter);
     71 
     72 static bool cn_redirect(dev_t *, int, int *, struct tty **);
     73 static void cn_release(struct tty *);
     74 
     75 const struct cdevsw cons_cdevsw = {
     76 	.d_open = cnopen,
     77 	.d_close = cnclose,
     78 	.d_read = cnread,
     79 	.d_write = cnwrite,
     80 	.d_ioctl = cnioctl,
     81 	.d_stop = nostop,
     82 	.d_tty = notty,
     83 	.d_poll = cnpoll,
     84 	.d_mmap = nommap,
     85 	.d_kqfilter = cnkqfilter,
     86 	.d_discard = nodiscard,
     87 	.d_flag = D_TTY|D_MPSAFE,
     88 };
     89 
     90 static struct kmutex cn_lock;
     91 
     92 struct	tty *volatile constty;	/* virtual console output device */
     93 struct	consdev *cn_tab;	/* physical console device info */
     94 struct	vnode *cn_devvp[2];	/* vnode for underlying device. */
     95 
     96 void
     97 cn_set_tab(struct consdev *tab)
     98 {
     99 
    100 	/*
    101 	 * This is a point that we should have KASSERT(cold) or add
    102 	 * synchronization in case this can happen after cold boot.
    103 	 * However, cn_tab initialization is so critical to any
    104 	 * diagnostics or debugging that we need to tread carefully
    105 	 * about introducing new ways to crash.  So let's put the
    106 	 * assertion in only after we've audited most or all of the
    107 	 * cn_tab updates.
    108 	 */
    109 	cn_tab = tab;
    110 }
    111 
    112 int
    113 cnopen(dev_t dev, int flag, int mode, struct lwp *l)
    114 {
    115 	dev_t cndev;
    116 	int unit, error;
    117 
    118 	unit = minor(dev);
    119 	if (unit > 1)
    120 		return ENODEV;
    121 
    122 	mutex_enter(&cn_lock);
    123 
    124 	if (cn_tab == NULL) {
    125 		error = 0;
    126 		goto out;
    127 	}
    128 
    129 	/*
    130 	 * always open the 'real' console device, so we don't get nailed
    131 	 * later.  This follows normal device semantics; they always get
    132 	 * open() calls.
    133 	 */
    134 	cndev = cn_tab->cn_dev;
    135 #if NNULLCONS > 0
    136 	if (cndev == NODEV) {
    137 		nullconsattach(0);
    138 	}
    139 #else /* NNULLCONS > 0 */
    140 	if (cndev == NODEV) {
    141 		/*
    142 		 * This is most likely an error in the console attach
    143 		 * code. Panicking looks better than jumping into nowhere
    144 		 * through cdevsw below....
    145 		 */
    146 		panic("cnopen: no console device");
    147 	}
    148 #endif /* NNULLCONS > 0 */
    149 	if (dev == cndev) {
    150 		/*
    151 		 * This causes cnopen() to be called recursively, which
    152 		 * is generally a bad thing.  It is often caused when
    153 		 * dev == 0 and cn_dev has not been set, but was probably
    154 		 * initialised to 0.
    155 		 */
    156 		panic("cnopen: cn_tab->cn_dev == dev");
    157 	}
    158 	if (cn_devvp[unit] != NULLVP) {
    159 		error = 0;
    160 		goto out;
    161 	}
    162 	if ((error = cdevvp(cndev, &cn_devvp[unit])) != 0) {
    163 		printf("cnopen: unable to get vnode reference\n");
    164 		goto out;
    165 	}
    166 	vn_lock(cn_devvp[unit], LK_EXCLUSIVE | LK_RETRY);
    167 	error = VOP_OPEN(cn_devvp[unit], flag, kauth_cred_get());
    168 	VOP_UNLOCK(cn_devvp[unit]);
    169 
    170 out:	mutex_exit(&cn_lock);
    171 	return error;
    172 }
    173 
    174 int
    175 cnclose(dev_t dev, int flag, int mode, struct lwp *l)
    176 {
    177 	struct vnode *vp;
    178 	int unit, error;
    179 
    180 	unit = minor(dev);
    181 	if (unit > 1)
    182 		return ENODEV;
    183 
    184 	mutex_enter(&cn_lock);
    185 
    186 	if (cn_tab == NULL) {
    187 		error = 0;
    188 		goto out;
    189 	}
    190 
    191 	vp = cn_devvp[unit];
    192 	cn_devvp[unit] = NULL;
    193 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    194 	error = VOP_CLOSE(vp, flag, kauth_cred_get());
    195 	VOP_UNLOCK(vp);
    196 	vrele(vp);
    197 
    198 out:	mutex_exit(&cn_lock);
    199 	return error;
    200 }
    201 
    202 int
    203 cnread(dev_t dev, struct uio *uio, int flag)
    204 {
    205 	struct tty *ctp = NULL;
    206 	int error;
    207 
    208 	/*
    209 	 * If we would redirect input, punt.  This will keep strange
    210 	 * things from happening to people who are using the real
    211 	 * console.  Nothing should be using /dev/console for
    212 	 * input (except a shell in single-user mode, but then,
    213 	 * one wouldn't TIOCCONS then).
    214 	 */
    215 	if (!cn_redirect(&dev, 1, &error, &ctp))
    216 		return error;
    217 	error = cdev_read(dev, uio, flag);
    218 	cn_release(ctp);
    219 	return error;
    220 }
    221 
    222 int
    223 cnwrite(dev_t dev, struct uio *uio, int flag)
    224 {
    225 	struct tty *ctp = NULL;
    226 	int error;
    227 
    228 	/* Redirect output, if that's appropriate. */
    229 	if (!cn_redirect(&dev, 0, &error, &ctp))
    230 		return error;
    231 	error = cdev_write(dev, uio, flag);
    232 	cn_release(ctp);
    233 	return error;
    234 }
    235 
    236 int
    237 cnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    238 {
    239 	struct tty *ctp = NULL;
    240 	int error;
    241 
    242 	error = 0;
    243 
    244 	/*
    245 	 * Superuser can always use this to wrest control of console
    246 	 * output from the "virtual" console.
    247 	 */
    248 	if (cmd == TIOCCONS) {
    249 		struct tty *tp;
    250 
    251 		mutex_enter(&constty_lock);
    252 		tp = atomic_load_relaxed(&constty);
    253 		if (tp == NULL) {
    254 			mutex_exit(&constty_lock);
    255 			goto passthrough; /* XXX ??? */
    256 		}
    257 		error = kauth_authorize_device_tty(l->l_cred,
    258 		    KAUTH_DEVICE_TTY_VIRTUAL, tp);
    259 		if (!error)
    260 			atomic_store_relaxed(&constty, NULL);
    261 		mutex_exit(&constty_lock);
    262 		return error;
    263 	}
    264 passthrough:
    265 	/*
    266 	 * Redirect the ioctl, if that's appropriate.
    267 	 * Note that strange things can happen, if a program does
    268 	 * ioctls on /dev/console, then the console is redirected
    269 	 * out from under it.
    270 	 */
    271 	if (!cn_redirect(&dev, 0, &error, &ctp))
    272 		return error;
    273 	error = cdev_ioctl(dev, cmd, data, flag, l);
    274 	cn_release(ctp);
    275 	return error;
    276 }
    277 
    278 /*ARGSUSED*/
    279 int
    280 cnpoll(dev_t dev, int events, struct lwp *l)
    281 {
    282 	struct tty *ctp = NULL;
    283 	int error;
    284 
    285 	/*
    286 	 * Redirect the poll, if that's appropriate.
    287 	 * I don't want to think of the possible side effects
    288 	 * of console redirection here.
    289 	 */
    290 	if (!cn_redirect(&dev, 0, &error, &ctp))
    291 		return POLLHUP;
    292 	error = cdev_poll(dev, events, l);
    293 	cn_release(ctp);
    294 	return error;
    295 }
    296 
    297 /*ARGSUSED*/
    298 int
    299 cnkqfilter(dev_t dev, struct knote *kn)
    300 {
    301 	struct tty *ctp = NULL;
    302 	int error;
    303 
    304 	/*
    305 	 * Redirect the kqfilter, if that's appropriate.
    306 	 * I don't want to think of the possible side effects
    307 	 * of console redirection here.
    308 	 */
    309 	if (!cn_redirect(&dev, 0, &error, &ctp))
    310 		return error;
    311 	error = cdev_kqfilter(dev, kn);
    312 	cn_release(ctp);
    313 	return error;
    314 }
    315 
    316 int
    317 cngetc(void)
    318 {
    319 	if (cn_tab == NULL)
    320 		return (0);
    321 	int s = splhigh();
    322 	for (;;) {
    323 		const int rv = (*cn_tab->cn_getc)(cn_tab->cn_dev);
    324 		if (rv >= 0) {
    325 			splx(s);
    326 			return rv;
    327 		}
    328 		docritpollhooks();
    329 	}
    330 }
    331 
    332 int
    333 cngetsn(char *cp, int size)
    334 {
    335 	char *lp;
    336 	int c, len;
    337 
    338 	cnpollc(1);
    339 
    340 	lp = cp;
    341 	len = 0;
    342 	for (;;) {
    343 		c = cngetc();
    344 		switch (c) {
    345 		case '\n':
    346 		case '\r':
    347 			printf("\n");
    348 			*lp++ = '\0';
    349 			cnpollc(0);
    350 			return (len);
    351 		case '\b':
    352 		case '\177':
    353 		case '#':
    354 			if (len) {
    355 				--len;
    356 				--lp;
    357 				printf("\b \b");
    358 			}
    359 			continue;
    360 		case '@':
    361 		case 'u'&037:	/* CTRL-u */
    362 			len = 0;
    363 			lp = cp;
    364 			printf("\n");
    365 			continue;
    366 		default:
    367 			if (len + 1 >= size || c < ' ') {
    368 				printf("\007");
    369 				continue;
    370 			}
    371 			printf("%c", c);
    372 			++len;
    373 			*lp++ = c;
    374 		}
    375 	}
    376 }
    377 
    378 void
    379 cnputc(int c)
    380 {
    381 
    382 	if (cn_tab == NULL)
    383 		return;
    384 
    385 /*
    386  * XXX
    387  * for some reason this causes ARCS firmware to output an endless stream of
    388  * whitespaces with n32 kernels, so use the pre-1.74 code for now until I can
    389  * figure out why this happens
    390  */
    391 #ifndef sgimips
    392 	if (c) {
    393 		if (c == '\n') {
    394 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    395 			docritpollhooks();
    396 		}
    397 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    398 	}
    399 #else
    400 	if (c) {
    401 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    402 		if (c == '\n') {
    403 			docritpollhooks();
    404 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    405 		}
    406 	}
    407 #endif
    408 }
    409 
    410 void
    411 cnpollc(int on)
    412 {
    413 	static int refcount = 0;
    414 
    415 	if (cn_tab == NULL)
    416 		return;
    417 	if (!on)
    418 		--refcount;
    419 	if (refcount == 0)
    420 		(*cn_tab->cn_pollc)(cn_tab->cn_dev, on);
    421 	if (on)
    422 		++refcount;
    423 }
    424 
    425 void
    426 nullcnpollc(dev_t dev, int on)
    427 {
    428 
    429 }
    430 
    431 void
    432 cnbell(u_int pitch, u_int period, u_int volume)
    433 {
    434 
    435 	if (cn_tab == NULL || cn_tab->cn_bell == NULL)
    436 		return;
    437 	(*cn_tab->cn_bell)(cn_tab->cn_dev, pitch, period, volume);
    438 }
    439 
    440 void
    441 cnflush(void)
    442 {
    443 	if (cn_tab == NULL || cn_tab->cn_flush == NULL)
    444 		return;
    445 	(*cn_tab->cn_flush)(cn_tab->cn_dev);
    446 }
    447 
    448 void
    449 cnhalt(void)
    450 {
    451 	if (cn_tab == NULL || cn_tab->cn_halt == NULL)
    452 		return;
    453 	(*cn_tab->cn_halt)(cn_tab->cn_dev);
    454 }
    455 
    456 /*
    457  * Redirect output, if that's appropriate.  If there's no real console,
    458  * return ENXIO.
    459  */
    460 static bool
    461 cn_redirect(dev_t *devp, int is_read, int *error, struct tty **ctpp)
    462 {
    463 	dev_t dev = *devp;
    464 	struct tty *ctp;
    465 	int s;
    466 	bool ok = false;
    467 
    468 	*error = ENXIO;
    469 	*ctpp = NULL;
    470 	s = pserialize_read_enter();
    471 	if ((ctp = atomic_load_consume(&constty)) != NULL && minor(dev) == 0 &&
    472 	    (cn_tab == NULL || (cn_tab->cn_pri != CN_REMOTE))) {
    473 		if (is_read) {
    474 			*error = 0;
    475 			goto out;
    476 		}
    477 		tty_acquire(ctp);
    478 		*ctpp = ctp;
    479 		dev = ctp->t_dev;
    480 	} else if (cn_tab == NULL)
    481 		goto out;
    482 	else
    483 		dev = cn_tab->cn_dev;
    484 	ok = true;
    485 	*devp = dev;
    486 out:	pserialize_read_exit(s);
    487 	return ok;
    488 }
    489 
    490 static void
    491 cn_release(struct tty *ctp)
    492 {
    493 
    494 	if (ctp == NULL)
    495 		return;
    496 	tty_release(ctp);
    497 }
    498 
    499 MODULE(MODULE_CLASS_DRIVER, cons, NULL);
    500 
    501 static int
    502 cons_modcmd(modcmd_t cmd, void *arg)
    503 {
    504 
    505 	switch (cmd) {
    506 	case MODULE_CMD_INIT:
    507 		mutex_init(&cn_lock, MUTEX_DEFAULT, IPL_NONE);
    508 		return 0;
    509 	case MODULE_CMD_FINI:
    510 		mutex_destroy(&cn_lock);
    511 		return 0;
    512 	default:
    513 		return ENOTTY;
    514 	}
    515 }
    516