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cons.c revision 1.75.18.1 
      1 /*	$NetBSD: cons.c,v 1.75.18.1 2020/04/08 14:08:02 martin 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 1.75.18.1 2020/04/08 14:08:02 martin 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 	error = vn_lock(cn_devvp[unit], LK_EXCLUSIVE | LK_RETRY);
    137 	if (error == 0) {
    138 		error = VOP_OPEN(cn_devvp[unit], flag, kauth_cred_get());
    139 		VOP_UNLOCK(cn_devvp[unit]);
    140 	}
    141 	return error;
    142 }
    143 
    144 int
    145 cnclose(dev_t dev, int flag, int mode, struct lwp *l)
    146 {
    147 	struct vnode *vp;
    148 	int unit, error;
    149 
    150 	unit = minor(dev);
    151 
    152 	if (cn_tab == NULL)
    153 		return (0);
    154 
    155 	vp = cn_devvp[unit];
    156 	cn_devvp[unit] = NULL;
    157 	error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    158 	if (error == 0) {
    159 		error = VOP_CLOSE(vp, flag, kauth_cred_get());
    160 		VOP_UNLOCK(vp);
    161 		vrele(vp);
    162 	}
    163 	return error;
    164 }
    165 
    166 int
    167 cnread(dev_t dev, struct uio *uio, int flag)
    168 {
    169 	int error;
    170 
    171 	/*
    172 	 * If we would redirect input, punt.  This will keep strange
    173 	 * things from happening to people who are using the real
    174 	 * console.  Nothing should be using /dev/console for
    175 	 * input (except a shell in single-user mode, but then,
    176 	 * one wouldn't TIOCCONS then).
    177 	 */
    178 	if (!cn_redirect(&dev, 1, &error))
    179 		return error;
    180 	return cdev_read(dev, uio, flag);
    181 }
    182 
    183 int
    184 cnwrite(dev_t dev, struct uio *uio, int flag)
    185 {
    186 	int error;
    187 
    188 	/* Redirect output, if that's appropriate. */
    189 	if (!cn_redirect(&dev, 0, &error))
    190 		return error;
    191 	return cdev_write(dev, uio, flag);
    192 }
    193 
    194 int
    195 cnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    196 {
    197 	int error;
    198 
    199 	error = 0;
    200 
    201 	/*
    202 	 * Superuser can always use this to wrest control of console
    203 	 * output from the "virtual" console.
    204 	 */
    205 	if (cmd == TIOCCONS && constty != NULL) {
    206 		error = kauth_authorize_device_tty(l->l_cred,
    207 		    KAUTH_DEVICE_TTY_VIRTUAL, constty);
    208 		if (!error)
    209 			constty = NULL;
    210 		return (error);
    211 	}
    212 
    213 	/*
    214 	 * Redirect the ioctl, if that's appropriate.
    215 	 * Note that strange things can happen, if a program does
    216 	 * ioctls on /dev/console, then the console is redirected
    217 	 * out from under it.
    218 	 */
    219 	if (!cn_redirect(&dev, 0, &error))
    220 		return error;
    221 	return cdev_ioctl(dev, cmd, data, flag, l);
    222 }
    223 
    224 /*ARGSUSED*/
    225 int
    226 cnpoll(dev_t dev, int events, struct lwp *l)
    227 {
    228 	int error;
    229 
    230 	/*
    231 	 * Redirect the poll, if that's appropriate.
    232 	 * I don't want to think of the possible side effects
    233 	 * of console redirection here.
    234 	 */
    235 	if (!cn_redirect(&dev, 0, &error))
    236 		return POLLHUP;
    237 	return cdev_poll(dev, events, l);
    238 }
    239 
    240 /*ARGSUSED*/
    241 int
    242 cnkqfilter(dev_t dev, struct knote *kn)
    243 {
    244 	int error;
    245 
    246 	/*
    247 	 * Redirect the kqfilter, if that's appropriate.
    248 	 * I don't want to think of the possible side effects
    249 	 * of console redirection here.
    250 	 */
    251 	if (!cn_redirect(&dev, 0, &error))
    252 		return error;
    253 	return cdev_kqfilter(dev, kn);
    254 }
    255 
    256 int
    257 cngetc(void)
    258 {
    259 	if (cn_tab == NULL)
    260 		return (0);
    261 	int s = splhigh();
    262 	for (;;) {
    263 		const int rv = (*cn_tab->cn_getc)(cn_tab->cn_dev);
    264 		if (rv >= 0) {
    265 			splx(s);
    266 			return rv;
    267 		}
    268 		docritpollhooks();
    269 	}
    270 }
    271 
    272 int
    273 cngetsn(char *cp, int size)
    274 {
    275 	char *lp;
    276 	int c, len;
    277 
    278 	cnpollc(1);
    279 
    280 	lp = cp;
    281 	len = 0;
    282 	for (;;) {
    283 		c = cngetc();
    284 		switch (c) {
    285 		case '\n':
    286 		case '\r':
    287 			printf("\n");
    288 			*lp++ = '\0';
    289 			cnpollc(0);
    290 			return (len);
    291 		case '\b':
    292 		case '\177':
    293 		case '#':
    294 			if (len) {
    295 				--len;
    296 				--lp;
    297 				printf("\b \b");
    298 			}
    299 			continue;
    300 		case '@':
    301 		case 'u'&037:	/* CTRL-u */
    302 			len = 0;
    303 			lp = cp;
    304 			printf("\n");
    305 			continue;
    306 		default:
    307 			if (len + 1 >= size || c < ' ') {
    308 				printf("\007");
    309 				continue;
    310 			}
    311 			printf("%c", c);
    312 			++len;
    313 			*lp++ = c;
    314 		}
    315 	}
    316 }
    317 
    318 void
    319 cnputc(int c)
    320 {
    321 
    322 	if (cn_tab == NULL)
    323 		return;
    324 
    325 /*
    326  * XXX
    327  * for some reason this causes ARCS firmware to output an endless stream of
    328  * whitespaces with n32 kernels, so use the pre-1.74 code for now until I can
    329  * figure out why this happens
    330  */
    331 #ifndef sgimips
    332 	if (c) {
    333 		if (c == '\n') {
    334 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    335 			docritpollhooks();
    336 		}
    337 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    338 	}
    339 #else
    340 	if (c) {
    341 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    342 		if (c == '\n') {
    343 			docritpollhooks();
    344 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    345 		}
    346 	}
    347 #endif
    348 }
    349 
    350 void
    351 cnpollc(int on)
    352 {
    353 	static int refcount = 0;
    354 
    355 	if (cn_tab == NULL)
    356 		return;
    357 	if (!on)
    358 		--refcount;
    359 	if (refcount == 0)
    360 		(*cn_tab->cn_pollc)(cn_tab->cn_dev, on);
    361 	if (on)
    362 		++refcount;
    363 }
    364 
    365 void
    366 nullcnpollc(dev_t dev, int on)
    367 {
    368 
    369 }
    370 
    371 void
    372 cnbell(u_int pitch, u_int period, u_int volume)
    373 {
    374 
    375 	if (cn_tab == NULL || cn_tab->cn_bell == NULL)
    376 		return;
    377 	(*cn_tab->cn_bell)(cn_tab->cn_dev, pitch, period, volume);
    378 }
    379 
    380 void
    381 cnflush(void)
    382 {
    383 	if (cn_tab == NULL || cn_tab->cn_flush == NULL)
    384 		return;
    385 	(*cn_tab->cn_flush)(cn_tab->cn_dev);
    386 }
    387 
    388 void
    389 cnhalt(void)
    390 {
    391 	if (cn_tab == NULL || cn_tab->cn_halt == NULL)
    392 		return;
    393 	(*cn_tab->cn_halt)(cn_tab->cn_dev);
    394 }
    395 
    396 /*
    397  * Redirect output, if that's appropriate.  If there's no real console,
    398  * return ENXIO.
    399  *
    400  * Call with tty_mutex held.
    401  */
    402 static bool
    403 cn_redirect(dev_t *devp, int is_read, int *error)
    404 {
    405 	dev_t dev = *devp;
    406 
    407 	*error = ENXIO;
    408 	if (constty != NULL && minor(dev) == 0 &&
    409 	    (cn_tab == NULL || (cn_tab->cn_pri != CN_REMOTE))) {
    410 		if (is_read) {
    411 			*error = 0;
    412 			return false;
    413 		}
    414 		dev = constty->t_dev;
    415 	} else if (cn_tab == NULL)
    416 		return false;
    417 	else
    418 		dev = cn_tab->cn_dev;
    419 	*devp = dev;
    420 	return true;
    421 }
    422