xref: /netbsd-src/sys/kern/sys_generic.c (revision aad9773e38ed2370a628a6416e098f9008fc10a7)
1 /*	$NetBSD: sys_generic.c,v 1.130 2014/09/05 09:20:59 matt Exp $	*/
2 
3 /*-
4  * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Andrew Doran.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 /*
33  * Copyright (c) 1982, 1986, 1989, 1993
34  *	The Regents of the University of California.  All rights reserved.
35  * (c) UNIX System Laboratories, Inc.
36  * All or some portions of this file are derived from material licensed
37  * to the University of California by American Telephone and Telegraph
38  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
39  * the permission of UNIX System Laboratories, Inc.
40  *
41  * Redistribution and use in source and binary forms, with or without
42  * modification, are permitted provided that the following conditions
43  * are met:
44  * 1. Redistributions of source code must retain the above copyright
45  *    notice, this list of conditions and the following disclaimer.
46  * 2. Redistributions in binary form must reproduce the above copyright
47  *    notice, this list of conditions and the following disclaimer in the
48  *    documentation and/or other materials provided with the distribution.
49  * 3. Neither the name of the University nor the names of its contributors
50  *    may be used to endorse or promote products derived from this software
51  *    without specific prior written permission.
52  *
53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63  * SUCH DAMAGE.
64  *
65  *	@(#)sys_generic.c	8.9 (Berkeley) 2/14/95
66  */
67 
68 /*
69  * System calls relating to files.
70  */
71 
72 #include <sys/cdefs.h>
73 __KERNEL_RCSID(0, "$NetBSD: sys_generic.c,v 1.130 2014/09/05 09:20:59 matt Exp $");
74 
75 #include <sys/param.h>
76 #include <sys/systm.h>
77 #include <sys/filedesc.h>
78 #include <sys/ioctl.h>
79 #include <sys/file.h>
80 #include <sys/proc.h>
81 #include <sys/socketvar.h>
82 #include <sys/signalvar.h>
83 #include <sys/uio.h>
84 #include <sys/kernel.h>
85 #include <sys/stat.h>
86 #include <sys/kmem.h>
87 #include <sys/poll.h>
88 #include <sys/vnode.h>
89 #include <sys/mount.h>
90 #include <sys/syscallargs.h>
91 #include <sys/ktrace.h>
92 #include <sys/atomic.h>
93 #include <sys/disklabel.h>
94 
95 /*
96  * Read system call.
97  */
98 /* ARGSUSED */
99 int
100 sys_read(struct lwp *l, const struct sys_read_args *uap, register_t *retval)
101 {
102 	/* {
103 		syscallarg(int)		fd;
104 		syscallarg(void *)	buf;
105 		syscallarg(size_t)	nbyte;
106 	} */
107 	file_t *fp;
108 	int fd;
109 
110 	fd = SCARG(uap, fd);
111 
112 	if ((fp = fd_getfile(fd)) == NULL)
113 		return (EBADF);
114 
115 	if ((fp->f_flag & FREAD) == 0) {
116 		fd_putfile(fd);
117 		return (EBADF);
118 	}
119 
120 	/* dofileread() will unuse the descriptor for us */
121 	return (dofileread(fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
122 	    &fp->f_offset, FOF_UPDATE_OFFSET, retval));
123 }
124 
125 int
126 dofileread(int fd, struct file *fp, void *buf, size_t nbyte,
127 	off_t *offset, int flags, register_t *retval)
128 {
129 	struct iovec aiov;
130 	struct uio auio;
131 	size_t cnt;
132 	int error;
133 	lwp_t *l;
134 
135 	l = curlwp;
136 
137 	aiov.iov_base = (void *)buf;
138 	aiov.iov_len = nbyte;
139 	auio.uio_iov = &aiov;
140 	auio.uio_iovcnt = 1;
141 	auio.uio_resid = nbyte;
142 	auio.uio_rw = UIO_READ;
143 	auio.uio_vmspace = l->l_proc->p_vmspace;
144 
145 	/*
146 	 * Reads return ssize_t because -1 is returned on error.  Therefore
147 	 * we must restrict the length to SSIZE_MAX to avoid garbage return
148 	 * values.
149 	 */
150 	if (auio.uio_resid > SSIZE_MAX) {
151 		error = EINVAL;
152 		goto out;
153 	}
154 
155 	cnt = auio.uio_resid;
156 	error = (*fp->f_ops->fo_read)(fp, offset, &auio, fp->f_cred, flags);
157 	if (error)
158 		if (auio.uio_resid != cnt && (error == ERESTART ||
159 		    error == EINTR || error == EWOULDBLOCK))
160 			error = 0;
161 	cnt -= auio.uio_resid;
162 	ktrgenio(fd, UIO_READ, buf, cnt, error);
163 	*retval = cnt;
164  out:
165 	fd_putfile(fd);
166 	return (error);
167 }
168 
169 /*
170  * Scatter read system call.
171  */
172 int
173 sys_readv(struct lwp *l, const struct sys_readv_args *uap, register_t *retval)
174 {
175 	/* {
176 		syscallarg(int)				fd;
177 		syscallarg(const struct iovec *)	iovp;
178 		syscallarg(int)				iovcnt;
179 	} */
180 
181 	return do_filereadv(SCARG(uap, fd), SCARG(uap, iovp),
182 	    SCARG(uap, iovcnt), NULL, FOF_UPDATE_OFFSET, retval);
183 }
184 
185 int
186 do_filereadv(int fd, const struct iovec *iovp, int iovcnt,
187     off_t *offset, int flags, register_t *retval)
188 {
189 	struct uio	auio;
190 	struct iovec	*iov, *needfree = NULL, aiov[UIO_SMALLIOV];
191 	int		i, error;
192 	size_t		cnt;
193 	u_int		iovlen;
194 	struct file	*fp;
195 	struct iovec	*ktriov = NULL;
196 
197 	if (iovcnt == 0)
198 		return EINVAL;
199 
200 	if ((fp = fd_getfile(fd)) == NULL)
201 		return EBADF;
202 
203 	if ((fp->f_flag & FREAD) == 0) {
204 		fd_putfile(fd);
205 		return EBADF;
206 	}
207 
208 	if (offset == NULL)
209 		offset = &fp->f_offset;
210 	else {
211 		struct vnode *vp = fp->f_vnode;
212 		if (fp->f_type != DTYPE_VNODE || vp->v_type == VFIFO) {
213 			error = ESPIPE;
214 			goto out;
215 		}
216 		/*
217 		 * Test that the device is seekable ?
218 		 * XXX This works because no file systems actually
219 		 * XXX take any action on the seek operation.
220 		 */
221 		error = VOP_SEEK(vp, fp->f_offset, *offset, fp->f_cred);
222 		if (error != 0)
223 			goto out;
224 	}
225 
226 	iovlen = iovcnt * sizeof(struct iovec);
227 	if (flags & FOF_IOV_SYSSPACE)
228 		iov = __UNCONST(iovp);
229 	else {
230 		iov = aiov;
231 		if ((u_int)iovcnt > UIO_SMALLIOV) {
232 			if ((u_int)iovcnt > IOV_MAX) {
233 				error = EINVAL;
234 				goto out;
235 			}
236 			iov = kmem_alloc(iovlen, KM_SLEEP);
237 			if (iov == NULL) {
238 				error = ENOMEM;
239 				goto out;
240 			}
241 			needfree = iov;
242 		}
243 		error = copyin(iovp, iov, iovlen);
244 		if (error)
245 			goto done;
246 	}
247 
248 	auio.uio_iov = iov;
249 	auio.uio_iovcnt = iovcnt;
250 	auio.uio_rw = UIO_READ;
251 	auio.uio_vmspace = curproc->p_vmspace;
252 
253 	auio.uio_resid = 0;
254 	for (i = 0; i < iovcnt; i++, iov++) {
255 		auio.uio_resid += iov->iov_len;
256 		/*
257 		 * Reads return ssize_t because -1 is returned on error.
258 		 * Therefore we must restrict the length to SSIZE_MAX to
259 		 * avoid garbage return values.
260 		 */
261 		if (iov->iov_len > SSIZE_MAX || auio.uio_resid > SSIZE_MAX) {
262 			error = EINVAL;
263 			goto done;
264 		}
265 	}
266 
267 	/*
268 	 * if tracing, save a copy of iovec
269 	 */
270 	if (ktrpoint(KTR_GENIO))  {
271 		ktriov = kmem_alloc(iovlen, KM_SLEEP);
272 		if (ktriov != NULL)
273 			memcpy(ktriov, auio.uio_iov, iovlen);
274 	}
275 
276 	cnt = auio.uio_resid;
277 	error = (*fp->f_ops->fo_read)(fp, offset, &auio, fp->f_cred, flags);
278 	if (error)
279 		if (auio.uio_resid != cnt && (error == ERESTART ||
280 		    error == EINTR || error == EWOULDBLOCK))
281 			error = 0;
282 	cnt -= auio.uio_resid;
283 	*retval = cnt;
284 
285 	if (ktriov != NULL) {
286 		ktrgeniov(fd, UIO_READ, ktriov, cnt, error);
287 		kmem_free(ktriov, iovlen);
288 	}
289 
290  done:
291 	if (needfree)
292 		kmem_free(needfree, iovlen);
293  out:
294 	fd_putfile(fd);
295 	return (error);
296 }
297 
298 /*
299  * Write system call
300  */
301 int
302 sys_write(struct lwp *l, const struct sys_write_args *uap, register_t *retval)
303 {
304 	/* {
305 		syscallarg(int)			fd;
306 		syscallarg(const void *)	buf;
307 		syscallarg(size_t)		nbyte;
308 	} */
309 	file_t *fp;
310 	int fd;
311 
312 	fd = SCARG(uap, fd);
313 
314 	if ((fp = fd_getfile(fd)) == NULL)
315 		return (EBADF);
316 
317 	if ((fp->f_flag & FWRITE) == 0) {
318 		fd_putfile(fd);
319 		return (EBADF);
320 	}
321 
322 	/* dofilewrite() will unuse the descriptor for us */
323 	return (dofilewrite(fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
324 	    &fp->f_offset, FOF_UPDATE_OFFSET, retval));
325 }
326 
327 int
328 dofilewrite(int fd, struct file *fp, const void *buf,
329 	size_t nbyte, off_t *offset, int flags, register_t *retval)
330 {
331 	struct iovec aiov;
332 	struct uio auio;
333 	size_t cnt;
334 	int error;
335 
336 	aiov.iov_base = __UNCONST(buf);		/* XXXUNCONST kills const */
337 	aiov.iov_len = nbyte;
338 	auio.uio_iov = &aiov;
339 	auio.uio_iovcnt = 1;
340 	auio.uio_resid = nbyte;
341 	auio.uio_rw = UIO_WRITE;
342 	auio.uio_vmspace = curproc->p_vmspace;
343 
344 	/*
345 	 * Writes return ssize_t because -1 is returned on error.  Therefore
346 	 * we must restrict the length to SSIZE_MAX to avoid garbage return
347 	 * values.
348 	 */
349 	if (auio.uio_resid > SSIZE_MAX) {
350 		error = EINVAL;
351 		goto out;
352 	}
353 
354 	cnt = auio.uio_resid;
355 	error = (*fp->f_ops->fo_write)(fp, offset, &auio, fp->f_cred, flags);
356 	if (error) {
357 		if (auio.uio_resid != cnt && (error == ERESTART ||
358 		    error == EINTR || error == EWOULDBLOCK))
359 			error = 0;
360 		if (error == EPIPE && !(fp->f_flag & FNOSIGPIPE)) {
361 			mutex_enter(proc_lock);
362 			psignal(curproc, SIGPIPE);
363 			mutex_exit(proc_lock);
364 		}
365 	}
366 	cnt -= auio.uio_resid;
367 	ktrgenio(fd, UIO_WRITE, buf, cnt, error);
368 	*retval = cnt;
369  out:
370 	fd_putfile(fd);
371 	return (error);
372 }
373 
374 /*
375  * Gather write system call
376  */
377 int
378 sys_writev(struct lwp *l, const struct sys_writev_args *uap, register_t *retval)
379 {
380 	/* {
381 		syscallarg(int)				fd;
382 		syscallarg(const struct iovec *)	iovp;
383 		syscallarg(int)				iovcnt;
384 	} */
385 
386 	return do_filewritev(SCARG(uap, fd), SCARG(uap, iovp),
387 	    SCARG(uap, iovcnt), NULL, FOF_UPDATE_OFFSET, retval);
388 }
389 
390 int
391 do_filewritev(int fd, const struct iovec *iovp, int iovcnt,
392     off_t *offset, int flags, register_t *retval)
393 {
394 	struct uio	auio;
395 	struct iovec	*iov, *needfree = NULL, aiov[UIO_SMALLIOV];
396 	int		i, error;
397 	size_t		cnt;
398 	u_int		iovlen;
399 	struct file	*fp;
400 	struct iovec	*ktriov = NULL;
401 
402 	if (iovcnt == 0)
403 		return EINVAL;
404 
405 	if ((fp = fd_getfile(fd)) == NULL)
406 		return EBADF;
407 
408 	if ((fp->f_flag & FWRITE) == 0) {
409 		fd_putfile(fd);
410 		return EBADF;
411 	}
412 
413 	if (offset == NULL)
414 		offset = &fp->f_offset;
415 	else {
416 		struct vnode *vp = fp->f_vnode;
417 		if (fp->f_type != DTYPE_VNODE || vp->v_type == VFIFO) {
418 			error = ESPIPE;
419 			goto out;
420 		}
421 		/*
422 		 * Test that the device is seekable ?
423 		 * XXX This works because no file systems actually
424 		 * XXX take any action on the seek operation.
425 		 */
426 		error = VOP_SEEK(vp, fp->f_offset, *offset, fp->f_cred);
427 		if (error != 0)
428 			goto out;
429 	}
430 
431 	iovlen = iovcnt * sizeof(struct iovec);
432 	if (flags & FOF_IOV_SYSSPACE)
433 		iov = __UNCONST(iovp);
434 	else {
435 		iov = aiov;
436 		if ((u_int)iovcnt > UIO_SMALLIOV) {
437 			if ((u_int)iovcnt > IOV_MAX) {
438 				error = EINVAL;
439 				goto out;
440 			}
441 			iov = kmem_alloc(iovlen, KM_SLEEP);
442 			if (iov == NULL) {
443 				error = ENOMEM;
444 				goto out;
445 			}
446 			needfree = iov;
447 		}
448 		error = copyin(iovp, iov, iovlen);
449 		if (error)
450 			goto done;
451 	}
452 
453 	auio.uio_iov = iov;
454 	auio.uio_iovcnt = iovcnt;
455 	auio.uio_rw = UIO_WRITE;
456 	auio.uio_vmspace = curproc->p_vmspace;
457 
458 	auio.uio_resid = 0;
459 	for (i = 0; i < iovcnt; i++, iov++) {
460 		auio.uio_resid += iov->iov_len;
461 		/*
462 		 * Writes return ssize_t because -1 is returned on error.
463 		 * Therefore we must restrict the length to SSIZE_MAX to
464 		 * avoid garbage return values.
465 		 */
466 		if (iov->iov_len > SSIZE_MAX || auio.uio_resid > SSIZE_MAX) {
467 			error = EINVAL;
468 			goto done;
469 		}
470 	}
471 
472 	/*
473 	 * if tracing, save a copy of iovec
474 	 */
475 	if (ktrpoint(KTR_GENIO))  {
476 		ktriov = kmem_alloc(iovlen, KM_SLEEP);
477 		if (ktriov != NULL)
478 			memcpy(ktriov, auio.uio_iov, iovlen);
479 	}
480 
481 	cnt = auio.uio_resid;
482 	error = (*fp->f_ops->fo_write)(fp, offset, &auio, fp->f_cred, flags);
483 	if (error) {
484 		if (auio.uio_resid != cnt && (error == ERESTART ||
485 		    error == EINTR || error == EWOULDBLOCK))
486 			error = 0;
487 		if (error == EPIPE && !(fp->f_flag & FNOSIGPIPE)) {
488 			mutex_enter(proc_lock);
489 			psignal(curproc, SIGPIPE);
490 			mutex_exit(proc_lock);
491 		}
492 	}
493 	cnt -= auio.uio_resid;
494 	*retval = cnt;
495 
496 	if (ktriov != NULL) {
497 		ktrgeniov(fd, UIO_WRITE, ktriov, cnt, error);
498 		kmem_free(ktriov, iovlen);
499 	}
500 
501  done:
502 	if (needfree)
503 		kmem_free(needfree, iovlen);
504  out:
505 	fd_putfile(fd);
506 	return (error);
507 }
508 
509 /*
510  * Ioctl system call
511  */
512 /* ARGSUSED */
513 int
514 sys_ioctl(struct lwp *l, const struct sys_ioctl_args *uap, register_t *retval)
515 {
516 	/* {
517 		syscallarg(int)		fd;
518 		syscallarg(u_long)	com;
519 		syscallarg(void *)	data;
520 	} */
521 	struct file	*fp;
522 	proc_t		*p;
523 	u_long		com;
524 	int		error;
525 	size_t		size, alloc_size;
526 	void 		*data, *memp;
527 #define	STK_PARAMS	128
528 	u_long		stkbuf[STK_PARAMS/sizeof(u_long)];
529 #if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
530 	size_t		zero_last = 0;
531 #define	zero_size(SZ)	((SZ)+zero_last)
532 #else
533 #define	zero_size(SZ)	(SZ)
534 #endif
535 
536 	memp = NULL;
537 	alloc_size = 0;
538 	error = 0;
539 	p = l->l_proc;
540 
541 	if ((fp = fd_getfile(SCARG(uap, fd))) == NULL)
542 		return (EBADF);
543 
544 	if ((fp->f_flag & (FREAD | FWRITE)) == 0) {
545 		error = EBADF;
546 		com = 0;
547 		goto out;
548 	}
549 
550 	switch (com = SCARG(uap, com)) {
551 	case FIONCLEX:
552 	case FIOCLEX:
553 		fd_set_exclose(l, SCARG(uap, fd), com == FIOCLEX);
554 		goto out;
555 	}
556 
557 	/*
558 	 * Interpret high order word to find amount of data to be
559 	 * copied to/from the user's address space.
560 	 */
561 	size = IOCPARM_LEN(com);
562 	alloc_size = size;
563 
564 	/*
565 	 * The disklabel is now padded to a multiple of 8 bytes however the old
566 	 * disklabel on 32bit platforms wasn't.  This leaves a difference in
567 	 * size of 4 bytes between the two but are otherwise identical.
568 	 * To deal with this, we allocate enough space for the new disklabel
569 	 * but only copyin/out the smaller amount.
570 	 */
571 	if (IOCGROUP(com) == 'd') {
572 #if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
573 		u_long ocom = com;
574 #endif
575 		u_long ncom = com ^ (DIOCGDINFO ^ DIOCGDINFO32);
576 
577 #if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
578 	/*
579 	 * Userland might use struct disklabel that is bigger than the
580 	 * the kernel version (historic accident) - alloc userland
581 	 * size and zero unused part on copyout.
582 	 */
583 #define	DISKLABELLENDIFF	(sizeof(struct partition)	\
584 				       *(__TMPBIGMAXPARTITIONS-MAXPARTITIONS))
585 #define	IOCFIXUP(NIOC)	((NIOC&~(IOCPARM_MASK<<IOCPARM_SHIFT))	| \
586 			   (IOCPARM_LEN(NIOC)-DISKLABELLENDIFF)<<IOCPARM_SHIFT)
587 
588 		switch (IOCFIXUP(ocom)) {
589 		case DIOCGDINFO:
590 		case DIOCWDINFO:
591 		case DIOCSDINFO:
592 		case DIOCGDEFLABEL:
593 			com = ncom = IOCFIXUP(ocom);
594 			zero_last = DISKLABELLENDIFF;
595 			size -= DISKLABELLENDIFF;
596 			goto done;
597 		}
598 #endif
599 
600 		switch (ncom) {
601 		case DIOCGDINFO:
602 		case DIOCWDINFO:
603 		case DIOCSDINFO:
604 		case DIOCGDEFLABEL:
605 			com = ncom;
606 			if (IOCPARM_LEN(DIOCGDINFO32) < IOCPARM_LEN(DIOCGDINFO))
607 				alloc_size = IOCPARM_LEN(DIOCGDINFO);
608 			break;
609 		}
610 #if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
611 		done: ;
612 #endif
613 	}
614 	if (size > IOCPARM_MAX) {
615 		error = ENOTTY;
616 		goto out;
617 	}
618 	memp = NULL;
619 	if ((com >> IOCPARM_SHIFT) == 0)  {
620 		/* UNIX-style ioctl. */
621 		data = SCARG(uap, data);
622 	} else {
623 		if (alloc_size > sizeof(stkbuf)) {
624 			memp = kmem_alloc(alloc_size, KM_SLEEP);
625 			data = memp;
626 		} else {
627 			data = (void *)stkbuf;
628 		}
629 		if (com&IOC_IN) {
630 			if (size) {
631 				error = copyin(SCARG(uap, data), data, size);
632 				if (error) {
633 					goto out;
634 				}
635 				/*
636 				 * The data between size and alloc_size has
637 				 * not been overwritten.  It shouldn't matter
638 				 * but let's clear that anyway.
639 				 */
640 				if (__predict_false(size < alloc_size)) {
641 					memset((char *)data+size, 0,
642 					    alloc_size - size);
643 				}
644 				ktrgenio(SCARG(uap, fd), UIO_WRITE,
645 				    SCARG(uap, data), size, 0);
646 			} else {
647 				*(void **)data = SCARG(uap, data);
648 			}
649 		} else if ((com&IOC_OUT) && size) {
650 			/*
651 			 * Zero the buffer so the user always
652 			 * gets back something deterministic.
653 			 */
654 			memset(data, 0, zero_size(size));
655 		} else if (com&IOC_VOID) {
656 			*(void **)data = SCARG(uap, data);
657 		}
658 	}
659 
660 	switch (com) {
661 
662 	case FIONBIO:
663 		/* XXX Code block is not atomic */
664 		if (*(int *)data != 0)
665 			atomic_or_uint(&fp->f_flag, FNONBLOCK);
666 		else
667 			atomic_and_uint(&fp->f_flag, ~FNONBLOCK);
668 		error = (*fp->f_ops->fo_ioctl)(fp, FIONBIO, data);
669 		break;
670 
671 	case FIOASYNC:
672 		/* XXX Code block is not atomic */
673 		if (*(int *)data != 0)
674 			atomic_or_uint(&fp->f_flag, FASYNC);
675 		else
676 			atomic_and_uint(&fp->f_flag, ~FASYNC);
677 		error = (*fp->f_ops->fo_ioctl)(fp, FIOASYNC, data);
678 		break;
679 
680 	default:
681 		error = (*fp->f_ops->fo_ioctl)(fp, com, data);
682 		/*
683 		 * Copy any data to user, size was
684 		 * already set and checked above.
685 		 */
686 		if (error == 0 && (com&IOC_OUT) && size) {
687 			error = copyout(data, SCARG(uap, data),
688 			    zero_size(size));
689 			ktrgenio(SCARG(uap, fd), UIO_READ, SCARG(uap, data),
690 			    size, error);
691 		}
692 		break;
693 	}
694  out:
695 	if (memp)
696 		kmem_free(memp, alloc_size);
697 	fd_putfile(SCARG(uap, fd));
698 	switch (error) {
699 	case -1:
700 		printf("sys_ioctl: _IO%s%s('%c', %lu, %lu) returned -1: "
701 		    "pid=%d comm=%s\n",
702 		    (com & IOC_IN) ? "W" : "", (com & IOC_OUT) ? "R" : "",
703 		    (char)IOCGROUP(com), (com & 0xff), IOCPARM_LEN(com),
704 		    p->p_pid, p->p_comm);
705 		/* FALLTHROUGH */
706 	case EPASSTHROUGH:
707 		error = ENOTTY;
708 		/* FALLTHROUGH */
709 	default:
710 		return (error);
711 	}
712 }
713