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kern_subr.c revision 1.25 
      1 /*	$NetBSD: kern_subr.c,v 1.25 1997/06/12 17:12:20 mrg Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1997 Jason R. Thorpe.  All rights reserved.
      5  * Copyright (c) 1982, 1986, 1991, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  * (c) UNIX System Laboratories, Inc.
      8  * All or some portions of this file are derived from material licensed
      9  * to the University of California by American Telephone and Telegraph
     10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     11  * the permission of UNIX System Laboratories, Inc.
     12  *
     13  * Copyright (c) 1992, 1993
     14  *	The Regents of the University of California.  All rights reserved.
     15  *
     16  * This software was developed by the Computer Systems Engineering group
     17  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
     18  * contributed to Berkeley.
     19  *
     20  * All advertising materials mentioning features or use of this software
     21  * must display the following acknowledgement:
     22  *	This product includes software developed by the University of
     23  *	California, Lawrence Berkeley Laboratory.
     24  *
     25  * Redistribution and use in source and binary forms, with or without
     26  * modification, are permitted provided that the following conditions
     27  * are met:
     28  * 1. Redistributions of source code must retain the above copyright
     29  *    notice, this list of conditions and the following disclaimer.
     30  * 2. Redistributions in binary form must reproduce the above copyright
     31  *    notice, this list of conditions and the following disclaimer in the
     32  *    documentation and/or other materials provided with the distribution.
     33  * 3. All advertising materials mentioning features or use of this software
     34  *    must display the following acknowledgement:
     35  *	This product includes software developed by the University of
     36  *	California, Berkeley and its contributors.
     37  * 4. Neither the name of the University nor the names of its contributors
     38  *    may be used to endorse or promote products derived from this software
     39  *    without specific prior written permission.
     40  *
     41  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     51  * SUCH DAMAGE.
     52  *
     53  *	@(#)kern_subr.c	8.3 (Berkeley) 1/21/94
     54  */
     55 
     56 #include <sys/param.h>
     57 #include <sys/systm.h>
     58 #include <sys/proc.h>
     59 #include <sys/malloc.h>
     60 #include <sys/mount.h>
     61 #include <sys/device.h>
     62 #include <sys/reboot.h>
     63 #include <sys/conf.h>
     64 #include <sys/disklabel.h>
     65 #include <sys/queue.h>
     66 
     67 #include <dev/cons.h>
     68 
     69 #include <net/if.h>
     70 
     71 /* XXX these should eventually move to subr_autoconf.c */
     72 static int findblkmajor __P((const char *, struct devnametobdevmaj *));
     73 static const char *findblkname __P((int, struct devnametobdevmaj *));
     74 static struct device *getdisk __P((char *, int, int,
     75 	struct devnametobdevmaj *, dev_t *));
     76 static struct device *parsedisk __P((char *, int, int,
     77 	struct devnametobdevmaj *, dev_t *));
     78 static int getstr __P((char *, int));
     79 
     80 int
     81 uiomove(buf, n, uio)
     82 	register void *buf;
     83 	register int n;
     84 	register struct uio *uio;
     85 {
     86 	register struct iovec *iov;
     87 	u_int cnt;
     88 	int error = 0;
     89 	char *cp = buf;
     90 
     91 #ifdef DIAGNOSTIC
     92 	if (uio->uio_rw != UIO_READ && uio->uio_rw != UIO_WRITE)
     93 		panic("uiomove: mode");
     94 	if (uio->uio_segflg == UIO_USERSPACE && uio->uio_procp != curproc)
     95 		panic("uiomove proc");
     96 #endif
     97 	while (n > 0 && uio->uio_resid) {
     98 		iov = uio->uio_iov;
     99 		cnt = iov->iov_len;
    100 		if (cnt == 0) {
    101 			uio->uio_iov++;
    102 			uio->uio_iovcnt--;
    103 			continue;
    104 		}
    105 		if (cnt > n)
    106 			cnt = n;
    107 		switch (uio->uio_segflg) {
    108 
    109 		case UIO_USERSPACE:
    110 			if (uio->uio_rw == UIO_READ)
    111 				error = copyout(cp, iov->iov_base, cnt);
    112 			else
    113 				error = copyin(iov->iov_base, cp, cnt);
    114 			if (error)
    115 				return (error);
    116 			break;
    117 
    118 		case UIO_SYSSPACE:
    119 			if (uio->uio_rw == UIO_READ)
    120 				bcopy(cp, iov->iov_base, cnt);
    121 			else
    122 				bcopy(iov->iov_base, cp, cnt);
    123 			break;
    124 		}
    125 		iov->iov_base += cnt;
    126 		iov->iov_len -= cnt;
    127 		uio->uio_resid -= cnt;
    128 		uio->uio_offset += cnt;
    129 		cp += cnt;
    130 		n -= cnt;
    131 	}
    132 	return (error);
    133 }
    134 
    135 /*
    136  * Give next character to user as result of read.
    137  */
    138 int
    139 ureadc(c, uio)
    140 	register int c;
    141 	register struct uio *uio;
    142 {
    143 	register struct iovec *iov;
    144 
    145 	if (uio->uio_resid <= 0)
    146 		panic("ureadc: non-positive resid");
    147 again:
    148 	if (uio->uio_iovcnt <= 0)
    149 		panic("ureadc: non-positive iovcnt");
    150 	iov = uio->uio_iov;
    151 	if (iov->iov_len <= 0) {
    152 		uio->uio_iovcnt--;
    153 		uio->uio_iov++;
    154 		goto again;
    155 	}
    156 	switch (uio->uio_segflg) {
    157 
    158 	case UIO_USERSPACE:
    159 		if (subyte(iov->iov_base, c) < 0)
    160 			return (EFAULT);
    161 		break;
    162 
    163 	case UIO_SYSSPACE:
    164 		*iov->iov_base = c;
    165 		break;
    166 	}
    167 	iov->iov_base++;
    168 	iov->iov_len--;
    169 	uio->uio_resid--;
    170 	uio->uio_offset++;
    171 	return (0);
    172 }
    173 
    174 /*
    175  * General routine to allocate a hash table.
    176  */
    177 void *
    178 hashinit(elements, type, hashmask)
    179 	int elements, type;
    180 	u_long *hashmask;
    181 {
    182 	long hashsize;
    183 	LIST_HEAD(generic, generic) *hashtbl;
    184 	int i;
    185 
    186 	if (elements <= 0)
    187 		panic("hashinit: bad cnt");
    188 	for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
    189 		continue;
    190 	hashsize >>= 1;
    191 	hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
    192 	for (i = 0; i < hashsize; i++)
    193 		LIST_INIT(&hashtbl[i]);
    194 	*hashmask = hashsize - 1;
    195 	return (hashtbl);
    196 }
    197 
    198 /*
    199  * "Shutdown hook" types, functions, and variables.
    200  */
    201 
    202 struct shutdownhook_desc {
    203 	LIST_ENTRY(shutdownhook_desc) sfd_list;
    204 	void	(*sfd_fn) __P((void *));
    205 	void	*sfd_arg;
    206 };
    207 
    208 LIST_HEAD(, shutdownhook_desc) shutdownhook_list;
    209 
    210 void *
    211 shutdownhook_establish(fn, arg)
    212 	void (*fn) __P((void *));
    213 	void *arg;
    214 {
    215 	struct shutdownhook_desc *ndp;
    216 
    217 	ndp = (struct shutdownhook_desc *)
    218 	    malloc(sizeof (*ndp), M_DEVBUF, M_NOWAIT);
    219 	if (ndp == NULL)
    220 		return NULL;
    221 
    222 	ndp->sfd_fn = fn;
    223 	ndp->sfd_arg = arg;
    224 	LIST_INSERT_HEAD(&shutdownhook_list, ndp, sfd_list);
    225 
    226 	return (ndp);
    227 }
    228 
    229 void
    230 shutdownhook_disestablish(vhook)
    231 	void *vhook;
    232 {
    233 #ifdef DIAGNOSTIC
    234 	struct shutdownhook_desc *dp;
    235 
    236 	for (dp = shutdownhook_list.lh_first; dp != NULL;
    237 	    dp = dp->sfd_list.le_next)
    238                 if (dp == vhook)
    239 			break;
    240 	if (dp == NULL)
    241 		panic("shutdownhook_disestablish: hook not established");
    242 #endif
    243 
    244 	LIST_REMOVE((struct shutdownhook_desc *)vhook, sfd_list);
    245 	free(vhook, M_DEVBUF);
    246 }
    247 
    248 /*
    249  * Run shutdown hooks.  Should be invoked immediately before the
    250  * system is halted or rebooted, i.e. after file systems unmounted,
    251  * after crash dump done, etc.
    252  *
    253  * Each shutdown hook is removed from the list before it's run, so that
    254  * it won't be run again.
    255  */
    256 void
    257 doshutdownhooks()
    258 {
    259 	struct shutdownhook_desc *dp;
    260 
    261 	while ((dp = shutdownhook_list.lh_first) != NULL) {
    262 		LIST_REMOVE(dp, sfd_list);
    263 		(*dp->sfd_fn)(dp->sfd_arg);
    264 #if 0
    265 		/*
    266 		 * Don't bother freeing the hook structure,, since we may
    267 		 * be rebooting because of a memory corruption problem,
    268 		 * and this might only make things worse.  It doesn't
    269 		 * matter, anyway, since the system is just about to
    270 		 * reboot.
    271 		 */
    272 		free(dp, M_DEVBUF);
    273 #endif
    274 	}
    275 }
    276 
    277 /*
    278  * "Mountroot hook" types, functions, and variables.
    279  */
    280 
    281 struct mountroothook_desc {
    282 	LIST_ENTRY(mountroothook_desc) mrd_list;
    283 	struct	device *mrd_device;
    284 	void 	(*mrd_func) __P((struct device *));
    285 };
    286 
    287 LIST_HEAD(, mountroothook_desc) mountroothook_list;
    288 
    289 void *
    290 mountroothook_establish(func, dev)
    291 	void (*func) __P((struct device *));
    292 	struct device *dev;
    293 {
    294 	struct mountroothook_desc *mrd;
    295 
    296 	mrd = (struct mountroothook_desc *)
    297 	    malloc(sizeof(*mrd), M_DEVBUF, M_NOWAIT);
    298 	if (mrd == NULL)
    299 		return (NULL);
    300 
    301 	mrd->mrd_device = dev;
    302 	mrd->mrd_func = func;
    303 	LIST_INSERT_HEAD(&mountroothook_list, mrd, mrd_list);
    304 
    305 	return (mrd);
    306 }
    307 
    308 void
    309 mountroothook_disestablish(vhook)
    310 	void *vhook;
    311 {
    312 #ifdef DIAGNOSTIC
    313 	struct mountroothook_desc *mrd;
    314 
    315 	for (mrd = mountroothook_list.lh_first; mrd != NULL;
    316 	    mrd = mrd->mrd_list.le_next)
    317                 if (mrd == vhook)
    318 			break;
    319 	if (mrd == NULL)
    320 		panic("mountroothook_disestablish: hook not established");
    321 #endif
    322 
    323 	LIST_REMOVE((struct mountroothook_desc *)vhook, mrd_list);
    324 	free(vhook, M_DEVBUF);
    325 }
    326 
    327 void
    328 mountroothook_destroy()
    329 {
    330 	struct mountroothook_desc *mrd;
    331 
    332 	while ((mrd = mountroothook_list.lh_first) != NULL) {
    333 		LIST_REMOVE(mrd, mrd_list);
    334 		free(mrd, M_DEVBUF);
    335 	}
    336 }
    337 
    338 void
    339 domountroothook()
    340 {
    341 	struct mountroothook_desc *mrd;
    342 
    343 	for (mrd = mountroothook_list.lh_first; mrd != NULL;
    344 	    mrd = mrd->mrd_list.le_next) {
    345 		if (mrd->mrd_device == root_device) {
    346 			(*mrd->mrd_func)(root_device);
    347 			return;
    348 		}
    349 	}
    350 }
    351 
    352 /*
    353  * Determine the root device and, if instructed to, the root file system.
    354  */
    355 
    356 #include "md.h"
    357 #if NMD == 0
    358 #undef MEMORY_DISK_HOOKS
    359 #endif
    360 
    361 #ifdef MEMORY_DISK_HOOKS
    362 static struct device fakemdrootdev = { DV_DISK, {}, NULL, 0, "md0", NULL };
    363 #endif
    364 
    365 void
    366 setroot(bootdv, bootpartition, nam2blk)
    367 	struct device *bootdv;
    368 	int bootpartition;
    369 	struct devnametobdevmaj *nam2blk;
    370 {
    371 	struct device *dv;
    372 	register int len, i;
    373 	dev_t nrootdev;
    374 	char buf[128];
    375 	const char *rootdevname;
    376 	struct device *rootdv;
    377 	struct ifnet *ifp;
    378 	const char *deffsname;
    379 	struct vfsops *vops;
    380 	extern int (*mountroot) __P((void));
    381 	static struct devnametobdevmaj *last_nam2blk;
    382 
    383 	if (nam2blk == NULL) {
    384 		if (last_nam2blk == NULL)
    385 			panic("setroot: no name to bdev major map");
    386 		nam2blk = last_nam2blk;
    387 	}
    388 	last_nam2blk = nam2blk;
    389 
    390 #ifdef MEMORY_DISK_IS_ROOT
    391 	bootdv = &fakemdrootdev;
    392 	bootpartition = 0;
    393 #endif
    394 
    395 	/*
    396 	 * If NFS is specified as the file system, and we found
    397 	 * a DV_DISK boot device (or no boot device at all), then
    398 	 * find a reasonable network interface for "rootspec".
    399 	 */
    400 	vops = vfs_getopsbyname("nfs");
    401 	if (vops != NULL && vops->vfs_mountroot == mountroot &&
    402 	    rootspec == NULL &&
    403 	    (bootdv == NULL || bootdv->dv_class != DV_IFNET)) {
    404 		for (ifp = ifnet.tqh_first; ifp != NULL;
    405 		    ifp = ifp->if_list.tqe_next)
    406 			if ((ifp->if_flags &
    407 			     (IFF_LOOPBACK|IFF_POINTOPOINT)) == 0)
    408 				break;
    409 		if (ifp == NULL) {
    410 			/*
    411 			 * Can't find a suitable interface; ask the
    412 			 * user.
    413 			 */
    414 			boothowto |= RB_ASKNAME;
    415 		} else {
    416 			/*
    417 			 * Have a suitable interface; behave as if
    418 			 * the user specified this interface.
    419 			 */
    420 			rootspec = (const char *)ifp->if_xname;
    421 		}
    422 	}
    423 
    424 	/*
    425 	 * If wildcarded root and we the boot device wasn't determined,
    426 	 * ask the user.
    427 	 */
    428 	if (rootspec == NULL && bootdv == NULL)
    429 		boothowto |= RB_ASKNAME;
    430 
    431  top:
    432 	if (boothowto & RB_ASKNAME) {
    433 		for (;;) {
    434 			printf("root device");
    435 			if (bootdv != NULL) {
    436 				printf(" (default %s", bootdv->dv_xname);
    437 				if (bootdv->dv_class == DV_DISK)
    438 					printf("%c", bootpartition + 'a');
    439 				printf(")");
    440 			}
    441 			printf(": ");
    442 			len = getstr(buf, sizeof(buf));
    443 			if (len == 0 && bootdv != NULL) {
    444 				strcpy(buf, bootdv->dv_xname);
    445 				len = strlen(buf);
    446 			}
    447 			if (len > 0 && buf[len - 1] == '*') {
    448 				buf[--len] = '\0';
    449 				dv = getdisk(buf, len, 1, nam2blk, &nrootdev);
    450 				if (dv != NULL) {
    451 					rootdv = dv;
    452 					break;
    453 				}
    454 			}
    455 			dv = getdisk(buf, len, bootpartition, nam2blk,
    456 			    &nrootdev);
    457 			if (dv != NULL) {
    458 				rootdv = dv;
    459 				break;
    460 			}
    461 		}
    462 
    463 		rootdev = nrootdev;
    464 
    465 		for (i = 0; i < nvfssw; i++) {
    466 			if (vfssw[i] != NULL &&
    467 			    vfssw[i]->vfs_mountroot != NULL &&
    468 			    vfssw[i]->vfs_mountroot == mountroot)
    469 				break;
    470 		}
    471 		if (i >= nvfssw) {
    472 			mountroot = NULL;
    473 			deffsname = "generic";
    474 		} else
    475 			deffsname = vfssw[i]->vfs_name;
    476 		for (;;) {
    477 			printf("file system (default %s): ", deffsname);
    478 			len = getstr(buf, sizeof(buf));
    479 			if (len == 0)
    480 				break;
    481 			if (len == 4 && strcmp(buf, "halt") == 0)
    482 				cpu_reboot(RB_HALT, NULL);
    483 			else if (len == 7 && strcmp(buf, "generic") == 0) {
    484 				mountroot = NULL;
    485 				break;
    486 			}
    487 			vops = vfs_getopsbyname(buf);
    488 			if (vops == NULL || vops->vfs_mountroot == NULL) {
    489 				printf("use one of: generic");
    490 				for (i = 0; i < nvfssw; i++)
    491 					if (vfssw[i] != NULL &&
    492 					    vfssw[i]->vfs_mountroot != NULL)
    493 						printf(" %s",
    494 						    vfssw[i]->vfs_name);
    495 				printf(" halt\n");
    496 			} else {
    497 				mountroot = vops->vfs_mountroot;
    498 				break;
    499 			}
    500 		}
    501 
    502 	} else if (rootspec == NULL) {
    503 		int majdev;
    504 
    505 		/*
    506 		 * Wildcarded root; use the boot device.
    507 		 */
    508 		majdev = findblkmajor(bootdv->dv_xname, nam2blk);
    509 		if (majdev >= 0) {
    510 			/*
    511 			 * Root is on a disk.  `bootpartition' is root.
    512 			 */
    513 			rootdv = bootdv;
    514 			rootdev = MAKEDISKDEV(majdev, bootdv->dv_unit,
    515 			    bootpartition);
    516 		} else {
    517 			/*
    518 			 * Root is on the net.
    519 			 */
    520 			rootdv = bootdv;
    521 		}
    522 		/* Initialise dumpdev */
    523 		dumpdev = NODEV;
    524 	} else {
    525 
    526 		/*
    527 		 * `root on <dev> ...'
    528 		 */
    529 
    530 		/*
    531 		 * If it's a network interface, we can bail out
    532 		 * early.
    533 		 */
    534 		for (dv = alldevs.tqh_first; dv != NULL;
    535 		    dv = dv->dv_list.tqe_next)
    536 			if (strcmp(dv->dv_xname, rootspec) == 0)
    537 				break;
    538 		if (dv != NULL && dv->dv_class == DV_IFNET) {
    539 			root_device = dv;
    540 			return;
    541 		}
    542 
    543 		rootdevname = findblkname(major(rootdev), nam2blk);
    544 		if (rootdevname == NULL) {
    545 			printf("unknown device major 0x%x\n", rootdev);
    546 			boothowto |= RB_ASKNAME;
    547 			goto top;
    548 		}
    549 		bzero(buf, sizeof(buf));
    550 		sprintf(buf, "%s%d", rootdevname, DISKUNIT(rootdev));
    551 
    552 		for (dv = alldevs.tqh_first; dv != NULL;
    553 		    dv = dv->dv_list.tqe_next) {
    554 			if (strcmp(buf, dv->dv_xname) == 0) {
    555 				root_device = dv;
    556 				break;
    557 			}
    558 		}
    559 		if (dv == NULL) {
    560 			printf("device %s (0x%x) not configured\n",
    561 			    buf, rootdev);
    562 			boothowto |= RB_ASKNAME;
    563 			goto top;
    564 		}
    565 
    566 		return;
    567 	}
    568 
    569 	root_device = rootdv;
    570 
    571 	switch (rootdv->dv_class) {
    572 	case DV_IFNET:
    573 		return;
    574 
    575 	case DV_DISK:
    576 		printf("root on %s%c", rootdv->dv_xname,
    577 		    DISKPART(rootdev) + 'a');
    578 		printf("\n");
    579 		break;
    580 
    581 	default:
    582 		printf("can't determine root device\n");
    583 		boothowto |= RB_ASKNAME;
    584 		goto top;
    585 	}
    586 }
    587 
    588 static int
    589 findblkmajor(name, nam2blk)
    590 	const char *name;
    591 	struct devnametobdevmaj *nam2blk;
    592 {
    593 	int i;
    594 
    595 	if (nam2blk == NULL)
    596 		return (-1);
    597 
    598 	for (i = 0; nam2blk[i].d_name != NULL; i++)
    599 		if (strncmp(name, nam2blk[i].d_name,
    600 		    strlen(nam2blk[i].d_name)) == 0)
    601 			return (nam2blk[i].d_maj);
    602 	return (-1);
    603 }
    604 
    605 const char *
    606 findblkname(maj, nam2blk)
    607 	int maj;
    608 	struct devnametobdevmaj *nam2blk;
    609 {
    610 	int i;
    611 
    612 	if (nam2blk == NULL)
    613 		return (NULL);
    614 
    615 	for (i = 0; nam2blk[i].d_name != NULL; i++)
    616 		if (nam2blk[i].d_maj == maj)
    617 			return (nam2blk[i].d_name);
    618 	return (NULL);
    619 }
    620 
    621 static struct device *
    622 getdisk(str, len, defpart, nam2blk, devp)
    623 	char *str;
    624 	int len, defpart;
    625 	struct devnametobdevmaj *nam2blk;
    626 	dev_t *devp;
    627 {
    628 	struct device *dv;
    629 
    630 	if ((dv = parsedisk(str, len, defpart, nam2blk, devp)) == NULL) {
    631 		printf("use one of:");
    632 #ifdef MEMORY_DISK_HOOKS
    633 		printf(" %s[a-%c]", fakemdrootdev.dv_xname,
    634 		    'a' + MAXPARTITIONS - 1);
    635 #endif
    636 		for (dv = alldevs.tqh_first; dv != NULL;
    637 		    dv = dv->dv_list.tqe_next) {
    638 			if (dv->dv_class == DV_DISK)
    639 				printf(" %s[a-%c]", dv->dv_xname,
    640 				    'a' + MAXPARTITIONS - 1);
    641 			if (dv->dv_class == DV_IFNET)
    642 				printf(" %s", dv->dv_xname);
    643 		}
    644 		printf(" halt\n");
    645 	}
    646 	return (dv);
    647 }
    648 
    649 static struct device *
    650 parsedisk(str, len, defpart, nam2blk, devp)
    651 	char *str;
    652 	int len, defpart;
    653 	struct devnametobdevmaj *nam2blk;
    654 	dev_t *devp;
    655 {
    656 	struct device *dv;
    657 	char *cp, c;
    658 	int majdev, part;
    659 
    660 	if (len == 0)
    661 		return (NULL);
    662 
    663 	if (len == 4 && strcmp(str, "halt") == 0)
    664 		cpu_reboot(RB_HALT, NULL);
    665 
    666 	cp = str + len - 1;
    667 	c = *cp;
    668 	if (c >= 'a' && c <= ('a' + MAXPARTITIONS - 1)) {
    669 		part = c - 'a';
    670 		*cp = '\0';
    671 	} else
    672 		part = defpart;
    673 
    674 #ifdef MEMORY_DISK_HOOKS
    675 	if (strcmp(str, fakemdrootdev.dv_xname) == 0) {
    676 		dv = &fakemdrootdev;
    677 		goto gotdisk;
    678 	}
    679 #endif
    680 
    681 	for (dv = alldevs.tqh_first; dv != NULL; dv = dv->dv_list.tqe_next) {
    682 		if (dv->dv_class == DV_DISK &&
    683 		    strcmp(str, dv->dv_xname) == 0) {
    684 #ifdef MEMORY_DISK_HOOKS
    685  gotdisk:
    686 #endif
    687 			majdev = findblkmajor(dv->dv_xname, nam2blk);
    688 			if (majdev < 0)
    689 				panic("parsedisk");
    690 			*devp = MAKEDISKDEV(majdev, dv->dv_unit, part);
    691 			break;
    692 		}
    693 
    694 		if (dv->dv_class == DV_IFNET &&
    695 		    strcmp(str, dv->dv_xname) == 0) {
    696 			*devp = NODEV;
    697 			break;
    698 		}
    699 	}
    700 
    701 	*cp = c;
    702 	return (dv);
    703 }
    704 
    705 /*
    706  * XXX shouldn't this be a common function?
    707  */
    708 static int
    709 getstr(cp, size)
    710 	char *cp;
    711 	int size;
    712 {
    713 	char *lp;
    714 	int c, len;
    715 
    716 	cnpollc(1);
    717 
    718 	lp = cp;
    719 	len = 0;
    720 	for (;;) {
    721 		c = cngetc();
    722 		switch (c) {
    723 		case '\n':
    724 		case '\r':
    725 			printf("\n");
    726 			*lp++ = '\0';
    727 			cnpollc(0);
    728 			return (len);
    729 		case '\b':
    730 		case '\177':
    731 		case '#':
    732 			if (len) {
    733 				--len;
    734 				--lp;
    735 				printf("\b \b");
    736 			}
    737 			continue;
    738 		case '@':
    739 		case 'u'&037:
    740 			len = 0;
    741 			lp = cp;
    742 			printf("\n");
    743 			continue;
    744 		default:
    745 			if (len + 1 >= size || c < ' ') {
    746 				printf("\007");
    747 				continue;
    748 			}
    749 			printf("%c", c);
    750 			++len;
    751 			*lp++ = c;
    752 		}
    753 	}
    754 }
    755