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cons.c revision 1.69.2.2 
      1 /*	$NetBSD: cons.c,v 1.69.2.2 2017/12/03 11:36:58 jdolecek 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 1.69.2.2 2017/12/03 11:36:58 jdolecek 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 	}
    162 	return error;
    163 }
    164 
    165 int
    166 cnread(dev_t dev, struct uio *uio, int flag)
    167 {
    168 	int error;
    169 
    170 	/*
    171 	 * If we would redirect input, punt.  This will keep strange
    172 	 * things from happening to people who are using the real
    173 	 * console.  Nothing should be using /dev/console for
    174 	 * input (except a shell in single-user mode, but then,
    175 	 * one wouldn't TIOCCONS then).
    176 	 */
    177 	if (!cn_redirect(&dev, 1, &error))
    178 		return error;
    179 	return cdev_read(dev, uio, flag);
    180 }
    181 
    182 int
    183 cnwrite(dev_t dev, struct uio *uio, int flag)
    184 {
    185 	int error;
    186 
    187 	/* Redirect output, if that's appropriate. */
    188 	if (!cn_redirect(&dev, 0, &error))
    189 		return error;
    190 	return cdev_write(dev, uio, flag);
    191 }
    192 
    193 int
    194 cnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    195 {
    196 	int error;
    197 
    198 	error = 0;
    199 
    200 	/*
    201 	 * Superuser can always use this to wrest control of console
    202 	 * output from the "virtual" console.
    203 	 */
    204 	if (cmd == TIOCCONS && constty != NULL) {
    205 		error = kauth_authorize_device_tty(l->l_cred,
    206 		    KAUTH_DEVICE_TTY_VIRTUAL, constty);
    207 		if (!error)
    208 			constty = NULL;
    209 		return (error);
    210 	}
    211 
    212 	/*
    213 	 * Redirect the ioctl, if that's appropriate.
    214 	 * Note that strange things can happen, if a program does
    215 	 * ioctls on /dev/console, then the console is redirected
    216 	 * out from under it.
    217 	 */
    218 	if (!cn_redirect(&dev, 0, &error))
    219 		return error;
    220 	return cdev_ioctl(dev, cmd, data, flag, l);
    221 }
    222 
    223 /*ARGSUSED*/
    224 int
    225 cnpoll(dev_t dev, int events, struct lwp *l)
    226 {
    227 	int error;
    228 
    229 	/*
    230 	 * Redirect the poll, if that's appropriate.
    231 	 * I don't want to think of the possible side effects
    232 	 * of console redirection here.
    233 	 */
    234 	if (!cn_redirect(&dev, 0, &error))
    235 		return POLLHUP;
    236 	return cdev_poll(dev, events, l);
    237 }
    238 
    239 /*ARGSUSED*/
    240 int
    241 cnkqfilter(dev_t dev, struct knote *kn)
    242 {
    243 	int error;
    244 
    245 	/*
    246 	 * Redirect the kqfilter, if that's appropriate.
    247 	 * I don't want to think of the possible side effects
    248 	 * of console redirection here.
    249 	 */
    250 	if (!cn_redirect(&dev, 0, &error))
    251 		return error;
    252 	return cdev_kqfilter(dev, kn);
    253 }
    254 
    255 int
    256 cngetc(void)
    257 {
    258 	if (cn_tab == NULL)
    259 		return (0);
    260 	int s = splhigh();
    261 	for (;;) {
    262 		const int rv = (*cn_tab->cn_getc)(cn_tab->cn_dev);
    263 		if (rv >= 0) {
    264 			splx(s);
    265 			return rv;
    266 		}
    267 		docritpollhooks();
    268 	}
    269 }
    270 
    271 int
    272 cngetsn(char *cp, int size)
    273 {
    274 	char *lp;
    275 	int c, len;
    276 
    277 	cnpollc(1);
    278 
    279 	lp = cp;
    280 	len = 0;
    281 	for (;;) {
    282 		c = cngetc();
    283 		switch (c) {
    284 		case '\n':
    285 		case '\r':
    286 			printf("\n");
    287 			*lp++ = '\0';
    288 			cnpollc(0);
    289 			return (len);
    290 		case '\b':
    291 		case '\177':
    292 		case '#':
    293 			if (len) {
    294 				--len;
    295 				--lp;
    296 				printf("\b \b");
    297 			}
    298 			continue;
    299 		case '@':
    300 		case 'u'&037:	/* CTRL-u */
    301 			len = 0;
    302 			lp = cp;
    303 			printf("\n");
    304 			continue;
    305 		default:
    306 			if (len + 1 >= size || c < ' ') {
    307 				printf("\007");
    308 				continue;
    309 			}
    310 			printf("%c", c);
    311 			++len;
    312 			*lp++ = c;
    313 		}
    314 	}
    315 }
    316 
    317 void
    318 cnputc(int c)
    319 {
    320 
    321 	if (cn_tab == NULL)
    322 		return;
    323 
    324 /*
    325  * XXX
    326  * for some reason this causes ARCS firmware to output an endless stream of
    327  * whitespaces with n32 kernels, so use the pre-1.74 code for now until I can
    328  * figure out why this happens
    329  */
    330 #ifndef sgimips
    331 	if (c) {
    332 		if (c == '\n') {
    333 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    334 			docritpollhooks();
    335 		}
    336 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    337 	}
    338 #else
    339 	if (c) {
    340 		(*cn_tab->cn_putc)(cn_tab->cn_dev, c);
    341 		if (c == '\n') {
    342 			docritpollhooks();
    343 			(*cn_tab->cn_putc)(cn_tab->cn_dev, '\r');
    344 		}
    345 	}
    346 #endif
    347 }
    348 
    349 void
    350 cnpollc(int on)
    351 {
    352 	static int refcount = 0;
    353 
    354 	if (cn_tab == NULL)
    355 		return;
    356 	if (!on)
    357 		--refcount;
    358 	if (refcount == 0)
    359 		(*cn_tab->cn_pollc)(cn_tab->cn_dev, on);
    360 	if (on)
    361 		++refcount;
    362 }
    363 
    364 void
    365 nullcnpollc(dev_t dev, int on)
    366 {
    367 
    368 }
    369 
    370 void
    371 cnbell(u_int pitch, u_int period, u_int volume)
    372 {
    373 
    374 	if (cn_tab == NULL || cn_tab->cn_bell == NULL)
    375 		return;
    376 	(*cn_tab->cn_bell)(cn_tab->cn_dev, pitch, period, volume);
    377 }
    378 
    379 void
    380 cnflush(void)
    381 {
    382 	if (cn_tab == NULL || cn_tab->cn_flush == NULL)
    383 		return;
    384 	(*cn_tab->cn_flush)(cn_tab->cn_dev);
    385 }
    386 
    387 void
    388 cnhalt(void)
    389 {
    390 	if (cn_tab == NULL || cn_tab->cn_halt == NULL)
    391 		return;
    392 	(*cn_tab->cn_halt)(cn_tab->cn_dev);
    393 }
    394 
    395 /*
    396  * Redirect output, if that's appropriate.  If there's no real console,
    397  * return ENXIO.
    398  *
    399  * Call with tty_mutex held.
    400  */
    401 static bool
    402 cn_redirect(dev_t *devp, int is_read, int *error)
    403 {
    404 	dev_t dev = *devp;
    405 
    406 	*error = ENXIO;
    407 	if (constty != NULL && minor(dev) == 0 &&
    408 	    (cn_tab == NULL || (cn_tab->cn_pri != CN_REMOTE))) {
    409 		if (is_read) {
    410 			*error = 0;
    411 			return false;
    412 		}
    413 		dev = constty->t_dev;
    414 	} else if (cn_tab == NULL)
    415 		return false;
    416 	else
    417 		dev = cn_tab->cn_dev;
    418 	*devp = dev;
    419 	return true;
    420 }
    421