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cons.c revision 1.78 
      1 /*	$NetBSD: cons.c,v 1.78 2022/08/22 00:20:45 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 1.78 2022/08/22 00:20:45 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 
     57 #include <dev/cons.h>
     58 
     59 #include "nullcons.h"
     60 
     61 dev_type_open(cnopen);
     62 dev_type_close(cnclose);
     63 dev_type_read(cnread);
     64 dev_type_write(cnwrite);
     65 dev_type_ioctl(cnioctl);
     66 dev_type_poll(cnpoll);
     67 dev_type_kqfilter(cnkqfilter);
     68 
     69 static bool cn_redirect(dev_t *, int, int *);
     70 
     71 const struct cdevsw cons_cdevsw = {
     72 	.d_open = cnopen,
     73 	.d_close = cnclose,
     74 	.d_read = cnread,
     75 	.d_write = cnwrite,
     76 	.d_ioctl = cnioctl,
     77 	.d_stop = nostop,
     78 	.d_tty = notty,
     79 	.d_poll = cnpoll,
     80 	.d_mmap = nommap,
     81 	.d_kqfilter = cnkqfilter,
     82 	.d_discard = nodiscard,
     83 	.d_flag = D_TTY
     84 };
     85 
     86 struct	tty *constty = NULL;	/* virtual console output device */
     87 struct	consdev *cn_tab;	/* physical console device info */
     88 struct	vnode *cn_devvp[2];	/* vnode for underlying device. */
     89 
     90 int
     91 cnopen(dev_t dev, int flag, int mode, struct lwp *l)
     92 {
     93 	dev_t cndev;
     94 	int unit, error;
     95 
     96 	unit = minor(dev);
     97 	if (unit > 1)
     98 		return ENODEV;
     99 
    100 	if (cn_tab == NULL)
    101 		return (0);
    102 
    103 	/*
    104 	 * always open the 'real' console device, so we don't get nailed
    105 	 * later.  This follows normal device semantics; they always get
    106 	 * open() calls.
    107 	 */
    108 	cndev = cn_tab->cn_dev;
    109 #if NNULLCONS > 0
    110 	if (cndev == NODEV) {
    111 		nullconsattach(0);
    112 	}
    113 #else /* NNULLCONS > 0 */
    114 	if (cndev == NODEV) {
    115 		/*
    116 		 * This is most likely an error in the console attach
    117 		 * code. Panicking looks better than jumping into nowhere
    118 		 * through cdevsw below....
    119 		 */
    120 		panic("cnopen: no console device");
    121 	}
    122 #endif /* NNULLCONS > 0 */
    123 	if (dev == cndev) {
    124 		/*
    125 		 * This causes cnopen() to be called recursively, which
    126 		 * is generally a bad thing.  It is often caused when
    127 		 * dev == 0 and cn_dev has not been set, but was probably
    128 		 * initialised to 0.
    129 		 */
    130 		panic("cnopen: cn_tab->cn_dev == dev");
    131 	}
    132 	if (cn_devvp[unit] != NULLVP)
    133 		return 0;
    134 	if ((error = cdevvp(cndev, &cn_devvp[unit])) != 0)
    135 		printf("cnopen: unable to get vnode reference\n");
    136 	vn_lock(cn_devvp[unit], LK_EXCLUSIVE | LK_RETRY);
    137 	error = VOP_OPEN(cn_devvp[unit], flag, kauth_cred_get());
    138 	VOP_UNLOCK(cn_devvp[unit]);
    139 	return error;
    140 }
    141 
    142 int
    143 cnclose(dev_t dev, int flag, int mode, struct lwp *l)
    144 {
    145 	struct vnode *vp;
    146 	int unit, error;
    147 
    148 	unit = minor(dev);
    149 
    150 	if (cn_tab == NULL)
    151 		return (0);
    152 
    153 	vp = cn_devvp[unit];
    154 	cn_devvp[unit] = NULL;
    155 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    156 	error = VOP_CLOSE(vp, flag, kauth_cred_get());
    157 	VOP_UNLOCK(vp);
    158 	vrele(vp);
    159 	return error;
    160 }
    161 
    162 int
    163 cnread(dev_t dev, struct uio *uio, int flag)
    164 {
    165 	int error;
    166 
    167 	/*
    168 	 * If we would redirect input, punt.  This will keep strange
    169 	 * things from happening to people who are using the real
    170 	 * console.  Nothing should be using /dev/console for
    171 	 * input (except a shell in single-user mode, but then,
    172 	 * one wouldn't TIOCCONS then).
    173 	 */
    174 	if (!cn_redirect(&dev, 1, &error))
    175 		return error;
    176 	return cdev_read(dev, uio, flag);
    177 }
    178 
    179 int
    180 cnwrite(dev_t dev, struct uio *uio, int flag)
    181 {
    182 	int error;
    183 
    184 	/* Redirect output, if that's appropriate. */
    185 	if (!cn_redirect(&dev, 0, &error))
    186 		return error;
    187 	return cdev_write(dev, uio, flag);
    188 }
    189 
    190 int
    191 cnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    192 {
    193 	int error;
    194 
    195 	error = 0;
    196 
    197 	/*
    198 	 * Superuser can always use this to wrest control of console
    199 	 * output from the "virtual" console.
    200 	 */
    201 	if (cmd == TIOCCONS && constty != NULL) {
    202 		error = kauth_authorize_device_tty(l->l_cred,
    203 		    KAUTH_DEVICE_TTY_VIRTUAL, constty);
    204 		if (!error)
    205 			constty = NULL;
    206 		return (error);
    207 	}
    208 
    209 	/*
    210 	 * Redirect the ioctl, if that's appropriate.
    211 	 * Note that strange things can happen, if a program does
    212 	 * ioctls on /dev/console, then the console is redirected
    213 	 * out from under it.
    214 	 */
    215 	if (!cn_redirect(&dev, 0, &error))
    216 		return error;
    217 	return cdev_ioctl(dev, cmd, data, flag, l);
    218 }
    219 
    220 /*ARGSUSED*/
    221 int
    222 cnpoll(dev_t dev, int events, struct lwp *l)
    223 {
    224 	int error;
    225 
    226 	/*
    227 	 * Redirect the poll, if that's appropriate.
    228 	 * I don't want to think of the possible side effects
    229 	 * of console redirection here.
    230 	 */
    231 	if (!cn_redirect(&dev, 0, &error))
    232 		return POLLHUP;
    233 	return cdev_poll(dev, events, l);
    234 }
    235 
    236 /*ARGSUSED*/
    237 int
    238 cnkqfilter(dev_t dev, struct knote *kn)
    239 {
    240 	int error;
    241 
    242 	/*
    243 	 * Redirect the kqfilter, if that's appropriate.
    244 	 * I don't want to think of the possible side effects
    245 	 * of console redirection here.
    246 	 */
    247 	if (!cn_redirect(&dev, 0, &error))
    248 		return error;
    249 	return cdev_kqfilter(dev, kn);
    250 }
    251 
    252 int
    253 cngetc(void)
    254 {
    255 	if (cn_tab == NULL)
    256 		return (0);
    257 	int s = splhigh();
    258 	for (;;) {
    259 		const int rv = (*cn_tab->cn_getc)(cn_tab->cn_dev);
    260 		if (rv >= 0) {
    261 			splx(s);
    262 			return rv;
    263 		}
    264 		docritpollhooks();
    265 	}
    266 }
    267 
    268 int
    269 cngetsn(char *cp, int size)
    270 {
    271 	char *lp;
    272 	int c, len;
    273 
    274 	cnpollc(1);
    275 
    276 	lp = cp;
    277 	len = 0;
    278 	for (;;) {
    279 		c = cngetc();
    280 		switch (c) {
    281 		case '\n':
    282 		case '\r':
    283 			printf("\n");
    284 			*lp++ = '\0';
    285 			cnpollc(0);
    286 			return (len);
    287 		case '\b':
    288 		case '\177':
    289 		case '#':
    290 			if (len) {
    291 				--len;
    292 				--lp;
    293 				printf("\b \b");
    294 			}
    295 			continue;
    296 		case '@':
    297 		case 'u'&037:	/* CTRL-u */
    298 			len = 0;
    299 			lp = cp;
    300 			printf("\n");
    301 			continue;
    302 		default:
    303 			if (len + 1 >= size || c < ' ') {
    304 				printf("\007");
    305 				continue;
    306 			}
    307 			printf("%c", c);
    308 			++len;
    309 			*lp++ = c;
    310 		}
    311 	}
    312 }
    313 
    314 void
    315 cnputc(int c)
    316 {
    317 
    318 	if (cn_tab == NULL)
    319 		return;
    320 
    321 /*
    322  * XXX
    323  * for some reason this causes ARCS firmware to output an endless stream of
    324  * whitespaces with n32 kernels, so use the pre-1.74 code for now until I can
    325  * figure out why this happens
    326  */
    327 #ifndef sgimips
    328 	if (c) {
    329 		if (c == '\n') {
    330 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    331 			docritpollhooks();
    332 		}
    333 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    334 	}
    335 #else
    336 	if (c) {
    337 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    338 		if (c == '\n') {
    339 			docritpollhooks();
    340 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    341 		}
    342 	}
    343 #endif
    344 }
    345 
    346 void
    347 cnpollc(int on)
    348 {
    349 	static int refcount = 0;
    350 
    351 	if (cn_tab == NULL)
    352 		return;
    353 	if (!on)
    354 		--refcount;
    355 	if (refcount == 0)
    356 		(*cn_tab->cn_pollc)(cn_tab->cn_dev, on);
    357 	if (on)
    358 		++refcount;
    359 }
    360 
    361 void
    362 nullcnpollc(dev_t dev, int on)
    363 {
    364 
    365 }
    366 
    367 void
    368 cnbell(u_int pitch, u_int period, u_int volume)
    369 {
    370 
    371 	if (cn_tab == NULL || cn_tab->cn_bell == NULL)
    372 		return;
    373 	(*cn_tab->cn_bell)(cn_tab->cn_dev, pitch, period, volume);
    374 }
    375 
    376 void
    377 cnflush(void)
    378 {
    379 	if (cn_tab == NULL || cn_tab->cn_flush == NULL)
    380 		return;
    381 	(*cn_tab->cn_flush)(cn_tab->cn_dev);
    382 }
    383 
    384 void
    385 cnhalt(void)
    386 {
    387 	if (cn_tab == NULL || cn_tab->cn_halt == NULL)
    388 		return;
    389 	(*cn_tab->cn_halt)(cn_tab->cn_dev);
    390 }
    391 
    392 /*
    393  * Redirect output, if that's appropriate.  If there's no real console,
    394  * return ENXIO.
    395  *
    396  * Call with tty_mutex held.
    397  */
    398 static bool
    399 cn_redirect(dev_t *devp, int is_read, int *error)
    400 {
    401 	dev_t dev = *devp;
    402 
    403 	*error = ENXIO;
    404 	if (constty != NULL && minor(dev) == 0 &&
    405 	    (cn_tab == NULL || (cn_tab->cn_pri != CN_REMOTE))) {
    406 		if (is_read) {
    407 			*error = 0;
    408 			return false;
    409 		}
    410 		dev = constty->t_dev;
    411 	} else if (cn_tab == NULL)
    412 		return false;
    413 	else
    414 		dev = cn_tab->cn_dev;
    415 	*devp = dev;
    416 	return true;
    417 }
    418