1/*
2 * Copyright (c) 2000-2010 Apple, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
29/*
30 * Copyright (c) 1982, 1986, 1993
31 *	The Regents of the University of California.  All rights reserved.
32 *
33 * Redistribution and use in source and binary forms, with or without
34 * modification, are permitted provided that the following conditions
35 * are met:
36 * 1. Redistributions of source code must retain the above copyright
37 *    notice, this list of conditions and the following disclaimer.
38 * 2. Redistributions in binary form must reproduce the above copyright
39 *    notice, this list of conditions and the following disclaimer in the
40 *    documentation and/or other materials provided with the distribution.
41 * 3. All advertising materials mentioning features or use of this software
42 *    must display the following acknowledgement:
43 *	This product includes software developed by the University of
44 *	California, Berkeley and its contributors.
45 * 4. Neither the name of the University nor the names of its contributors
46 *    may be used to endorse or promote products derived from this software
47 *    without specific prior written permission.
48 *
49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59 * SUCH DAMAGE.
60 *
61 *	@(#)subr_log.c	8.3 (Berkeley) 2/14/95
62 */
63
64/*
65 * Error log buffer for kernel printf's.
66 */
67
68#include <sys/param.h>
69#include <sys/systm.h>
70#include <sys/proc_internal.h>
71#include <sys/vnode.h>
72#include <sys/ioctl.h>
73#include <sys/msgbuf.h>
74#include <sys/file_internal.h>
75#include <sys/errno.h>
76#include <sys/select.h>
77#include <sys/kernel.h>
78#include <kern/thread.h>
79#include <sys/lock.h>
80#include <sys/signalvar.h>
81#include <sys/conf.h>
82#include <sys/sysctl.h>
83#include <kern/kalloc.h>
84#include <pexpert/pexpert.h>
85
86/* XXX should be in a common header somewhere */
87extern void logwakeup(void);
88
89#define LOG_RDPRI	(PZERO + 1)
90
91#define LOG_NBIO	0x02
92#define LOG_ASYNC	0x04
93#define LOG_RDWAIT	0x08
94
95#define MAX_UNREAD_CHARS (CONFIG_MSG_BSIZE/2)
96/* All globals should be accessed under LOG_LOCK() */
97
98/* logsoftc only valid while log_open=1 */
99struct logsoftc {
100	int	sc_state;		/* see above for possibilities */
101	struct	selinfo sc_selp;	/* thread waiting for select */
102	int	sc_pgid;		/* process/group for async I/O */
103} logsoftc;
104
105int	log_open;			/* also used in log() */
106char smsg_bufc[CONFIG_MSG_BSIZE]; /* static buffer */
107struct msgbuf msgbuf = {MSG_MAGIC,sizeof(smsg_bufc),0,0,smsg_bufc};
108struct msgbuf *msgbufp __attribute__((used)) = &msgbuf;
109
110/* the following are implemented in osfmk/kern/printf.c  */
111extern void bsd_log_lock(void);
112extern void bsd_log_unlock(void);
113extern void bsd_log_init(void);
114
115/* XXX wants a linker set so these can be static */
116extern d_open_t         logopen;
117extern d_close_t        logclose;
118extern d_read_t         logread;
119extern d_ioctl_t        logioctl;
120extern d_select_t       logselect;
121
122/*
123 * Serialize log access.  Note that the log can be written at interrupt level,
124 * so any log manipulations that can be done from, or affect, another processor
125 * at interrupt level must be guarded with a spin lock.
126 */
127
128#define	LOG_LOCK() bsd_log_lock()
129#define	LOG_UNLOCK() bsd_log_unlock()
130
131#if DEBUG
132#define LOG_SETSIZE_DEBUG(x...) kprintf(x)
133#else
134#define LOG_SETSIZE_DEBUG(x...) do { } while(0)
135#endif
136
137static int sysctl_kern_msgbuf(struct sysctl_oid *oidp,
138				void *arg1,
139				int arg2,
140				struct sysctl_req *req);
141
142/*ARGSUSED*/
143int
144logopen(__unused dev_t dev, __unused int flags, __unused int mode, struct proc *p)
145{
146	LOG_LOCK();
147	if (log_open) {
148		LOG_UNLOCK();
149		return (EBUSY);
150	}
151	logsoftc.sc_pgid = p->p_pid;		/* signal process only */
152	log_open = 1;
153
154	LOG_UNLOCK();
155
156	return (0);
157}
158
159/*ARGSUSED*/
160int
161logclose(__unused dev_t dev, __unused int flag, __unused int devtype, __unused struct proc *p)
162{
163	LOG_LOCK();
164	selwakeup(&logsoftc.sc_selp);
165	selthreadclear(&logsoftc.sc_selp);
166	log_open = 0;
167	LOG_UNLOCK();
168	return (0);
169}
170
171/*ARGSUSED*/
172int
173logread(__unused dev_t dev, struct uio *uio, int flag)
174{
175	int l;
176	int error = 0;
177
178	LOG_LOCK();
179	while (msgbufp->msg_bufr == msgbufp->msg_bufx) {
180		if (flag & IO_NDELAY) {
181			error = EWOULDBLOCK;
182			goto out;
183		}
184		if (logsoftc.sc_state & LOG_NBIO) {
185			error = EWOULDBLOCK;
186			goto out;
187		}
188		logsoftc.sc_state |= LOG_RDWAIT;
189		LOG_UNLOCK();
190		/*
191		 * If the wakeup is missed
192		 * then wait for 5 sec and reevaluate
193		 */
194		if ((error = tsleep((caddr_t)msgbufp, LOG_RDPRI | PCATCH,
195				"klog", 5 * hz)) != 0) {
196			/* if it times out; ignore */
197			if (error != EWOULDBLOCK)
198				return (error);
199		}
200		LOG_LOCK();
201	}
202	logsoftc.sc_state &= ~LOG_RDWAIT;
203
204	while (uio_resid(uio) > 0) {
205		int readpos;
206
207		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
208		if (l < 0)
209			l = msgbufp->msg_size - msgbufp->msg_bufr;
210		l = min(l, uio_resid(uio));
211		if (l == 0)
212			break;
213
214		readpos = msgbufp->msg_bufr;
215		LOG_UNLOCK();
216		error = uiomove((caddr_t)&msgbufp->msg_bufc[readpos],
217			l, uio);
218		LOG_LOCK();
219		if (error)
220			break;
221		msgbufp->msg_bufr = readpos + l;
222		if (msgbufp->msg_bufr >= msgbufp->msg_size)
223			msgbufp->msg_bufr = 0;
224	}
225out:
226	LOG_UNLOCK();
227	return (error);
228}
229
230/*ARGSUSED*/
231int
232logselect(__unused dev_t dev, int rw, void * wql, struct proc *p)
233{
234	switch (rw) {
235
236	case FREAD:
237		LOG_LOCK();
238		if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
239			LOG_UNLOCK();
240			return (1);
241		}
242		selrecord(p, &logsoftc.sc_selp, wql);
243		LOG_UNLOCK();
244		break;
245	}
246	return (0);
247}
248
249void
250logwakeup(void)
251{
252	int pgid;
253
254	LOG_LOCK();
255	if (!log_open) {
256		LOG_UNLOCK();
257		return;
258	}
259	selwakeup(&logsoftc.sc_selp);
260	if (logsoftc.sc_state & LOG_ASYNC) {
261		pgid = logsoftc.sc_pgid;
262		LOG_UNLOCK();
263		if (pgid < 0)
264			gsignal(-pgid, SIGIO);
265		else
266			proc_signal(pgid, SIGIO);
267		LOG_LOCK();
268	}
269	if (logsoftc.sc_state & LOG_RDWAIT) {
270		wakeup((caddr_t)msgbufp);
271		logsoftc.sc_state &= ~LOG_RDWAIT;
272	}
273	LOG_UNLOCK();
274}
275
276
277/*ARGSUSED*/
278int
279logioctl(__unused dev_t dev, u_long com, caddr_t data, __unused int flag, __unused struct proc *p)
280{
281	int l;
282
283	LOG_LOCK();
284	switch (com) {
285
286	/* return number of characters immediately available */
287	case FIONREAD:
288		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
289		if (l < 0)
290			l += msgbufp->msg_size;
291		*(off_t *)data = l;
292		break;
293
294	case FIONBIO:
295		if (*(int *)data)
296			logsoftc.sc_state |= LOG_NBIO;
297		else
298			logsoftc.sc_state &= ~LOG_NBIO;
299		break;
300
301	case FIOASYNC:
302		if (*(int *)data)
303			logsoftc.sc_state |= LOG_ASYNC;
304		else
305			logsoftc.sc_state &= ~LOG_ASYNC;
306		break;
307
308	case TIOCSPGRP:
309		logsoftc.sc_pgid = *(int *)data;
310		break;
311
312	case TIOCGPGRP:
313		*(int *)data = logsoftc.sc_pgid;
314		break;
315
316	default:
317		LOG_UNLOCK();
318		return (-1);
319	}
320	LOG_UNLOCK();
321	return (0);
322}
323
324void
325bsd_log_init(void)
326{
327	/* After this point, we must be ready to accept characters */
328}
329
330
331/*
332 * log_putc_locked
333 *
334 * Decription:	Output a character to the log; assumes the LOG_LOCK() is held
335 *		by the caller.
336 *
337 * Parameters:	c				Character to output
338 *
339 * Returns:	(void)
340 *
341 * Notes:	This functions is used for multibyte output to the log; it
342 *		should be used preferrentially where possible to ensure that
343 *		log entries do not end up interspersed due to preemption or
344 *		SMP reentrancy.
345 */
346void
347log_putc_locked(char c)
348{
349	struct msgbuf *mbp;
350
351	mbp = msgbufp;
352	mbp->msg_bufc[mbp->msg_bufx++] = c;
353	if (mbp->msg_bufx >= msgbufp->msg_size)
354		mbp->msg_bufx = 0;
355}
356
357
358/*
359 * log_putc
360 *
361 * Decription:	Output a character to the log; assumes the LOG_LOCK() is NOT
362 *		held by the caller.
363 *
364 * Parameters:	c				Character to output
365 *
366 * Returns:	(void)
367 *
368 * Notes:	This function is used for syingle byte output to the log.  It
369 *		primarily exists to maintain binary backward compatibility.
370 */
371void
372log_putc(char c)
373{
374	int unread_count = 0;
375	LOG_LOCK();
376	log_putc_locked(c);
377	unread_count = msgbufp->msg_bufx - msgbufp->msg_bufr;
378	LOG_UNLOCK();
379
380	if (unread_count < 0)
381		unread_count = 0 - unread_count;
382	if (c == '\n' || unread_count >= MAX_UNREAD_CHARS)
383		logwakeup();
384}
385
386
387/*
388 * it is possible to increase the kernel log buffer size by adding
389 *   msgbuf=n
390 * to the kernel command line, and to read the current size using
391 *   sysctl kern.msgbuf
392 * If there is no parameter on the kernel command line, the buffer is
393 * allocated statically and is CONFIG_MSG_BSIZE characters in size, otherwise
394 * memory is dynamically allocated. Memory management must already be up.
395 */
396int
397log_setsize(int size) {
398	char *new_logdata;
399	int new_logsize, new_bufr, new_bufx;
400	char *old_logdata;
401	int old_logsize, old_bufr, old_bufx;
402	int i, count;
403	char *p, ch;
404
405	if (size > MAX_MSG_BSIZE)
406		return (EINVAL);
407
408	if (size <= 0)
409		return (EINVAL);
410
411	new_logsize = size;
412	if (!(new_logdata = (char*)kalloc(size))) {
413		printf("log_setsize: unable to allocate memory\n");
414		return (ENOMEM);
415	}
416	bzero(new_logdata, new_logsize);
417
418	LOG_LOCK();
419
420	old_logsize = msgbufp->msg_size;
421	old_logdata = msgbufp->msg_bufc;
422	old_bufr = msgbufp->msg_bufr;
423	old_bufx = msgbufp->msg_bufx;
424
425	LOG_SETSIZE_DEBUG("log_setsize(%d): old_logdata %p old_logsize %d old_bufr %d old_bufx %d\n",
426					  size, old_logdata, old_logsize, old_bufr, old_bufx);
427
428	/* start "new_logsize" bytes before the write pointer */
429	if (new_logsize <= old_bufx) {
430		count = new_logsize;
431		p = old_logdata + old_bufx - count;
432	} else {
433		/*
434		 * if new buffer is bigger, copy what we have and let the
435		 * bzero above handle the difference
436		 */
437		count = MIN(new_logsize, old_logsize);
438		p = old_logdata + old_logsize - (count - old_bufx);
439	}
440	for (i = 0; i < count; i++) {
441		if (p >= old_logdata + old_logsize)
442			p = old_logdata;
443
444		ch = *p++;
445		new_logdata[i] = ch;
446	}
447
448	new_bufx = i;
449	if (new_bufx >= new_logsize)
450		new_bufx = 0;
451	msgbufp->msg_bufx = new_bufx;
452
453	new_bufr = old_bufx - old_bufr; /* how much were we trailing bufx by? */
454	if (new_bufr < 0)
455		new_bufr += old_logsize;
456	new_bufr = new_bufx - new_bufr; /* now relative to oldest data in new buffer */
457	if (new_bufr < 0)
458		new_bufr += new_logsize;
459	msgbufp->msg_bufr = new_bufr;
460
461	msgbufp->msg_size = new_logsize;
462	msgbufp->msg_bufc = new_logdata;
463
464	LOG_SETSIZE_DEBUG("log_setsize(%d): new_logdata %p new_logsize %d new_bufr %d new_bufx %d\n",
465					  size, new_logdata, new_logsize, new_bufr, new_bufx);
466
467	LOG_UNLOCK();
468
469	/* this memory is now dead - clear it so that it compresses better
470	   in case of suspend to disk etc. */
471	bzero(old_logdata, old_logsize);
472	if (old_logdata != smsg_bufc) {
473		/* dynamic memory that must be freed */
474		kfree(old_logdata, old_logsize);
475	}
476
477	printf("set system log size to %d bytes\n", new_logsize);
478
479	return 0;
480}
481
482SYSCTL_PROC(_kern, OID_AUTO, msgbuf, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, 0, 0, sysctl_kern_msgbuf, "I", "");
483
484static int sysctl_kern_msgbuf(struct sysctl_oid *oidp __unused,
485							  void *arg1 __unused,
486							  int arg2 __unused,
487							  struct sysctl_req *req)
488{
489	int old_bufsize, bufsize;
490	int error;
491
492	LOG_LOCK();
493	old_bufsize = bufsize = msgbufp->msg_size;
494	LOG_UNLOCK();
495
496	error = sysctl_io_number(req, bufsize, sizeof(bufsize), &bufsize, NULL);
497	if (error)
498		return (error);
499
500	if (bufsize != old_bufsize) {
501		error = log_setsize(bufsize);
502	}
503
504	return (error);
505}
506
507
508/*
509 * This should be called by /sbin/dmesg only via libproc.
510 * It returns as much data still in the buffer as possible.
511 */
512int
513log_dmesg(user_addr_t buffer, uint32_t buffersize, int32_t * retval) {
514	uint32_t i;
515	uint32_t localbuff_size;
516	int error = 0, newl, skip;
517	char *localbuff, *p, *copystart, ch;
518	size_t copysize;
519
520	LOG_LOCK();
521	localbuff_size = (msgbufp->msg_size + 2); /* + '\n' + '\0' */
522	LOG_UNLOCK();
523
524	/* Allocate a temporary non-circular buffer for copyout */
525	if (!(localbuff = (char *)kalloc(localbuff_size))) {
526		printf("log_dmesg: unable to allocate memory\n");
527		return (ENOMEM);
528	}
529
530	/* in between here, the log could become bigger, but that's fine */
531	LOG_LOCK();
532
533	/*
534	 * The message buffer is circular; start at the write pointer, and
535	 * make one loop up to write pointer - 1.
536	 */
537	p = msgbufp->msg_bufc + msgbufp->msg_bufx;
538	for (i = newl = skip = 0; p != msgbufp->msg_bufc + msgbufp->msg_bufx - 1; ++p) {
539		if (p >= msgbufp->msg_bufc + msgbufp->msg_size)
540			p = msgbufp->msg_bufc;
541		ch = *p;
542		/* Skip "\n<.*>" syslog sequences. */
543		if (skip) {
544			if (ch == '>')
545				newl = skip = 0;
546			continue;
547		}
548		if (newl && ch == '<') {
549			skip = 1;
550			continue;
551		}
552		if (ch == '\0')
553			continue;
554		newl = (ch == '\n');
555		localbuff[i++] = ch;
556		/* The original version of this routine contained a buffer
557		 * overflow. At the time, a "small" targeted fix was desired
558		 * so the change below to check the buffer bounds was made.
559		 * TODO: rewrite this needlessly convoluted routine.
560		 */
561		if (i == (localbuff_size - 2))
562			break;
563	}
564	if (!newl)
565		localbuff[i++] = '\n';
566	localbuff[i++] = 0;
567
568	if (buffersize >= i) {
569		copystart = localbuff;
570		copysize = i;
571	} else {
572		copystart = localbuff + i - buffersize;
573		copysize = buffersize;
574	}
575
576	LOG_UNLOCK();
577
578	error = copyout(copystart, buffer, copysize);
579	if (!error)
580		*retval = copysize;
581
582	kfree(localbuff, localbuff_size);
583	return (error);
584}
585