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cons.c revision 1.81 
      1 /*	$NetBSD: cons.c,v 1.81 2022/10/03 19:12:51 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 1.81 2022/10/03 19:12:51 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 
     58 #include <dev/cons.h>
     59 
     60 #include "nullcons.h"
     61 
     62 dev_type_open(cnopen);
     63 dev_type_close(cnclose);
     64 dev_type_read(cnread);
     65 dev_type_write(cnwrite);
     66 dev_type_ioctl(cnioctl);
     67 dev_type_poll(cnpoll);
     68 dev_type_kqfilter(cnkqfilter);
     69 
     70 static bool cn_redirect(dev_t *, int, int *);
     71 
     72 const struct cdevsw cons_cdevsw = {
     73 	.d_open = cnopen,
     74 	.d_close = cnclose,
     75 	.d_read = cnread,
     76 	.d_write = cnwrite,
     77 	.d_ioctl = cnioctl,
     78 	.d_stop = nostop,
     79 	.d_tty = notty,
     80 	.d_poll = cnpoll,
     81 	.d_mmap = nommap,
     82 	.d_kqfilter = cnkqfilter,
     83 	.d_discard = nodiscard,
     84 	.d_flag = D_TTY
     85 };
     86 
     87 static struct kmutex cn_lock;
     88 
     89 struct	tty *constty = NULL;	/* virtual console output device */
     90 struct	consdev *cn_tab;	/* physical console device info */
     91 struct	vnode *cn_devvp[2];	/* vnode for underlying device. */
     92 
     93 void
     94 cn_set_tab(struct consdev *tab)
     95 {
     96 
     97 	/*
     98 	 * This is a point that we should have KASSERT(cold) or add
     99 	 * synchronization in case this can happen after cold boot.
    100 	 * However, cn_tab initialization is so critical to any
    101 	 * diagnostics or debugging that we need to tread carefully
    102 	 * about introducing new ways to crash.  So let's put the
    103 	 * assertion in only after we've audited most or all of the
    104 	 * cn_tab updates.
    105 	 */
    106 	cn_tab = tab;
    107 }
    108 
    109 int
    110 cnopen(dev_t dev, int flag, int mode, struct lwp *l)
    111 {
    112 	dev_t cndev;
    113 	int unit, error;
    114 
    115 	unit = minor(dev);
    116 	if (unit > 1)
    117 		return ENODEV;
    118 
    119 	mutex_enter(&cn_lock);
    120 
    121 	if (cn_tab == NULL) {
    122 		error = 0;
    123 		goto out;
    124 	}
    125 
    126 	/*
    127 	 * always open the 'real' console device, so we don't get nailed
    128 	 * later.  This follows normal device semantics; they always get
    129 	 * open() calls.
    130 	 */
    131 	cndev = cn_tab->cn_dev;
    132 #if NNULLCONS > 0
    133 	if (cndev == NODEV) {
    134 		nullconsattach(0);
    135 	}
    136 #else /* NNULLCONS > 0 */
    137 	if (cndev == NODEV) {
    138 		/*
    139 		 * This is most likely an error in the console attach
    140 		 * code. Panicking looks better than jumping into nowhere
    141 		 * through cdevsw below....
    142 		 */
    143 		panic("cnopen: no console device");
    144 	}
    145 #endif /* NNULLCONS > 0 */
    146 	if (dev == cndev) {
    147 		/*
    148 		 * This causes cnopen() to be called recursively, which
    149 		 * is generally a bad thing.  It is often caused when
    150 		 * dev == 0 and cn_dev has not been set, but was probably
    151 		 * initialised to 0.
    152 		 */
    153 		panic("cnopen: cn_tab->cn_dev == dev");
    154 	}
    155 	if (cn_devvp[unit] != NULLVP) {
    156 		error = 0;
    157 		goto out;
    158 	}
    159 	if ((error = cdevvp(cndev, &cn_devvp[unit])) != 0) {
    160 		printf("cnopen: unable to get vnode reference\n");
    161 		goto out;
    162 	}
    163 	vn_lock(cn_devvp[unit], LK_EXCLUSIVE | LK_RETRY);
    164 	error = VOP_OPEN(cn_devvp[unit], flag, kauth_cred_get());
    165 	VOP_UNLOCK(cn_devvp[unit]);
    166 
    167 out:	mutex_exit(&cn_lock);
    168 	return error;
    169 }
    170 
    171 int
    172 cnclose(dev_t dev, int flag, int mode, struct lwp *l)
    173 {
    174 	struct vnode *vp;
    175 	int unit, error;
    176 
    177 	unit = minor(dev);
    178 
    179 	mutex_enter(&cn_lock);
    180 
    181 	if (cn_tab == NULL) {
    182 		error = 0;
    183 		goto out;
    184 	}
    185 
    186 	vp = cn_devvp[unit];
    187 	cn_devvp[unit] = NULL;
    188 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    189 	error = VOP_CLOSE(vp, flag, kauth_cred_get());
    190 	VOP_UNLOCK(vp);
    191 	vrele(vp);
    192 
    193 out:	mutex_exit(&cn_lock);
    194 	return error;
    195 }
    196 
    197 int
    198 cnread(dev_t dev, struct uio *uio, int flag)
    199 {
    200 	int error;
    201 
    202 	/*
    203 	 * If we would redirect input, punt.  This will keep strange
    204 	 * things from happening to people who are using the real
    205 	 * console.  Nothing should be using /dev/console for
    206 	 * input (except a shell in single-user mode, but then,
    207 	 * one wouldn't TIOCCONS then).
    208 	 */
    209 	if (!cn_redirect(&dev, 1, &error))
    210 		return error;
    211 	return cdev_read(dev, uio, flag);
    212 }
    213 
    214 int
    215 cnwrite(dev_t dev, struct uio *uio, int flag)
    216 {
    217 	int error;
    218 
    219 	/* Redirect output, if that's appropriate. */
    220 	if (!cn_redirect(&dev, 0, &error))
    221 		return error;
    222 	return cdev_write(dev, uio, flag);
    223 }
    224 
    225 int
    226 cnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    227 {
    228 	int error;
    229 
    230 	error = 0;
    231 
    232 	/*
    233 	 * Superuser can always use this to wrest control of console
    234 	 * output from the "virtual" console.
    235 	 */
    236 	if (cmd == TIOCCONS && constty != NULL) {
    237 		error = kauth_authorize_device_tty(l->l_cred,
    238 		    KAUTH_DEVICE_TTY_VIRTUAL, constty);
    239 		if (!error)
    240 			constty = NULL;
    241 		return (error);
    242 	}
    243 
    244 	/*
    245 	 * Redirect the ioctl, if that's appropriate.
    246 	 * Note that strange things can happen, if a program does
    247 	 * ioctls on /dev/console, then the console is redirected
    248 	 * out from under it.
    249 	 */
    250 	if (!cn_redirect(&dev, 0, &error))
    251 		return error;
    252 	return cdev_ioctl(dev, cmd, data, flag, l);
    253 }
    254 
    255 /*ARGSUSED*/
    256 int
    257 cnpoll(dev_t dev, int events, struct lwp *l)
    258 {
    259 	int error;
    260 
    261 	/*
    262 	 * Redirect the poll, if that's appropriate.
    263 	 * I don't want to think of the possible side effects
    264 	 * of console redirection here.
    265 	 */
    266 	if (!cn_redirect(&dev, 0, &error))
    267 		return POLLHUP;
    268 	return cdev_poll(dev, events, l);
    269 }
    270 
    271 /*ARGSUSED*/
    272 int
    273 cnkqfilter(dev_t dev, struct knote *kn)
    274 {
    275 	int error;
    276 
    277 	/*
    278 	 * Redirect the kqfilter, if that's appropriate.
    279 	 * I don't want to think of the possible side effects
    280 	 * of console redirection here.
    281 	 */
    282 	if (!cn_redirect(&dev, 0, &error))
    283 		return error;
    284 	return cdev_kqfilter(dev, kn);
    285 }
    286 
    287 int
    288 cngetc(void)
    289 {
    290 	if (cn_tab == NULL)
    291 		return (0);
    292 	int s = splhigh();
    293 	for (;;) {
    294 		const int rv = (*cn_tab->cn_getc)(cn_tab->cn_dev);
    295 		if (rv >= 0) {
    296 			splx(s);
    297 			return rv;
    298 		}
    299 		docritpollhooks();
    300 	}
    301 }
    302 
    303 int
    304 cngetsn(char *cp, int size)
    305 {
    306 	char *lp;
    307 	int c, len;
    308 
    309 	cnpollc(1);
    310 
    311 	lp = cp;
    312 	len = 0;
    313 	for (;;) {
    314 		c = cngetc();
    315 		switch (c) {
    316 		case '\n':
    317 		case '\r':
    318 			printf("\n");
    319 			*lp++ = '\0';
    320 			cnpollc(0);
    321 			return (len);
    322 		case '\b':
    323 		case '\177':
    324 		case '#':
    325 			if (len) {
    326 				--len;
    327 				--lp;
    328 				printf("\b \b");
    329 			}
    330 			continue;
    331 		case '@':
    332 		case 'u'&037:	/* CTRL-u */
    333 			len = 0;
    334 			lp = cp;
    335 			printf("\n");
    336 			continue;
    337 		default:
    338 			if (len + 1 >= size || c < ' ') {
    339 				printf("\007");
    340 				continue;
    341 			}
    342 			printf("%c", c);
    343 			++len;
    344 			*lp++ = c;
    345 		}
    346 	}
    347 }
    348 
    349 void
    350 cnputc(int c)
    351 {
    352 
    353 	if (cn_tab == NULL)
    354 		return;
    355 
    356 /*
    357  * XXX
    358  * for some reason this causes ARCS firmware to output an endless stream of
    359  * whitespaces with n32 kernels, so use the pre-1.74 code for now until I can
    360  * figure out why this happens
    361  */
    362 #ifndef sgimips
    363 	if (c) {
    364 		if (c == '\n') {
    365 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    366 			docritpollhooks();
    367 		}
    368 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    369 	}
    370 #else
    371 	if (c) {
    372 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    373 		if (c == '\n') {
    374 			docritpollhooks();
    375 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    376 		}
    377 	}
    378 #endif
    379 }
    380 
    381 void
    382 cnpollc(int on)
    383 {
    384 	static int refcount = 0;
    385 
    386 	if (cn_tab == NULL)
    387 		return;
    388 	if (!on)
    389 		--refcount;
    390 	if (refcount == 0)
    391 		(*cn_tab->cn_pollc)(cn_tab->cn_dev, on);
    392 	if (on)
    393 		++refcount;
    394 }
    395 
    396 void
    397 nullcnpollc(dev_t dev, int on)
    398 {
    399 
    400 }
    401 
    402 void
    403 cnbell(u_int pitch, u_int period, u_int volume)
    404 {
    405 
    406 	if (cn_tab == NULL || cn_tab->cn_bell == NULL)
    407 		return;
    408 	(*cn_tab->cn_bell)(cn_tab->cn_dev, pitch, period, volume);
    409 }
    410 
    411 void
    412 cnflush(void)
    413 {
    414 	if (cn_tab == NULL || cn_tab->cn_flush == NULL)
    415 		return;
    416 	(*cn_tab->cn_flush)(cn_tab->cn_dev);
    417 }
    418 
    419 void
    420 cnhalt(void)
    421 {
    422 	if (cn_tab == NULL || cn_tab->cn_halt == NULL)
    423 		return;
    424 	(*cn_tab->cn_halt)(cn_tab->cn_dev);
    425 }
    426 
    427 /*
    428  * Redirect output, if that's appropriate.  If there's no real console,
    429  * return ENXIO.
    430  *
    431  * Call with tty_mutex held.
    432  */
    433 static bool
    434 cn_redirect(dev_t *devp, int is_read, int *error)
    435 {
    436 	dev_t dev = *devp;
    437 
    438 	*error = ENXIO;
    439 	if (constty != NULL && minor(dev) == 0 &&
    440 	    (cn_tab == NULL || (cn_tab->cn_pri != CN_REMOTE))) {
    441 		if (is_read) {
    442 			*error = 0;
    443 			return false;
    444 		}
    445 		dev = constty->t_dev;
    446 	} else if (cn_tab == NULL)
    447 		return false;
    448 	else
    449 		dev = cn_tab->cn_dev;
    450 	*devp = dev;
    451 	return true;
    452 }
    453 
    454 MODULE(MODULE_CLASS_DRIVER, cons, NULL);
    455 
    456 static int
    457 cons_modcmd(modcmd_t cmd, void *arg)
    458 {
    459 
    460 	switch (cmd) {
    461 	case MODULE_CMD_INIT:
    462 		mutex_init(&cn_lock, MUTEX_DEFAULT, IPL_NONE);
    463 		return 0;
    464 	case MODULE_CMD_FINI:
    465 		mutex_destroy(&cn_lock);
    466 		return 0;
    467 	default:
    468 		return ENOTTY;
    469 	}
    470 }
    471