text: /*
   * Copyright (c) 2000-2016 Apple, Inc. All rights reserved.
   *
   * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   *
   * This file contains Original Code and/or Modifications of Original Code
   * as defined in and that are subject to the Apple Public Source License
   * Version 2.0 (the 'License'). You may not use this file except in
   * compliance with the License. The rights granted to you under the License
   * may not be used to create, or enable the creation or redistribution of,
   * unlawful or unlicensed copies of an Apple operating system, or to
   * circumvent, violate, or enable the circumvention or violation of, any
   * terms of an Apple operating system software license agreement.
   *
   * Please obtain a copy of the License at
   * http://www.opensource.apple.com/apsl/ and read it before using this file.
   *
   * The Original Code and all software distributed under the License are
   * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
   * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
   * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
   * Please see the License for the specific language governing rights and
   * limitations under the License.
   *
   * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
   */
  /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  /*
   * Copyright (c) 1982, 1986, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	@(#)subr_log.c	8.3 (Berkeley) 2/14/95
   */
  
  /*
   * Error log buffer for kernel printf's.
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/proc_internal.h>
  #include <sys/vnode.h>
  #include <stdbool.h>
  #include <firehose/tracepoint_private.h>
  #include <firehose/chunk_private.h>
  #include <firehose/ioctl_private.h>
  #include <os/firehose_buffer_private.h>
  
  #include <os/log_private.h>
  #include <sys/ioctl.h>
  #include <sys/msgbuf.h>
  #include <sys/file_internal.h>
  #include <sys/errno.h>
  #include <sys/select.h>
  #include <sys/kernel.h>
  #include <kern/thread.h>
  #include <kern/sched_prim.h>
  #include <kern/simple_lock.h>
  #include <sys/lock.h>
  #include <sys/signalvar.h>
  #include <sys/conf.h>
  #include <sys/sysctl.h>
  #include <sys/queue.h>
  #include <kern/kalloc.h>
  #include <pexpert/pexpert.h>
  #include <mach/mach_port.h>
  #include <mach/mach_vm.h>
  #include <mach/vm_map.h>
  #include <vm/vm_kern.h>
  #include <kern/task.h>
  #include <kern/locks.h>
  
  /* XXX should be in a common header somewhere */
  extern void logwakeup(struct msgbuf *);
  extern void oslogwakeup(void);
  extern void oslog_streamwakeup(void);
  static void oslog_streamwakeup_locked(void);
  vm_offset_t kernel_firehose_addr = 0;
  
  /* log message counters for streaming mode */
  uint32_t oslog_s_streamed_msgcount = 0;
  uint32_t oslog_s_dropped_msgcount  = 0;
  extern uint32_t oslog_s_error_count;
  
  #define LOG_RDPRI	(PZERO + 1)
  
  #define LOG_NBIO	0x02
  #define LOG_ASYNC	0x04
  #define LOG_RDWAIT	0x08
  
  /* All globals should be accessed under LOG_LOCK() */
  
  static char amsg_bufc[1024];
  static struct msgbuf aslbuf = {MSG_MAGIC, sizeof (amsg_bufc), 0, 0, amsg_bufc};
  struct msgbuf *aslbufp __attribute__((used)) = &aslbuf;
  
  /* logsoftc only valid while log_open=1 */
  struct logsoftc {
  	int	sc_state;		/* see above for possibilities */
  	struct	selinfo sc_selp;	/* thread waiting for select */
  	int	sc_pgid;		/* process/group for async I/O */
  	struct msgbuf *sc_mbp;
  } logsoftc;
  
  static int log_open;
  char smsg_bufc[CONFIG_MSG_BSIZE]; /* static buffer */
  char oslog_stream_bufc[FIREHOSE_CHUNK_SIZE]; /* static buffer */
  struct firehose_chunk_s oslog_boot_buf = {
  	.fc_pos = {
  		.fcp_next_entry_offs = offsetof(struct firehose_chunk_s, fc_data),
  		.fcp_private_offs = FIREHOSE_CHUNK_SIZE,
  		.fcp_refcnt = 1, // indicate that there is a writer to this chunk
  		.fcp_stream = firehose_stream_persist,
  		.fcp_flag_io = 1, // for now, lets assume this is coming from the io bank
  	},
  }; /* static buffer */
  firehose_chunk_t firehose_boot_chunk = &oslog_boot_buf;
  struct msgbuf msgbuf = {MSG_MAGIC, sizeof(smsg_bufc), 0, 0, smsg_bufc};
  struct msgbuf oslog_stream_buf = {MSG_MAGIC, 0, 0, 0, NULL};
  struct msgbuf *msgbufp __attribute__((used)) = &msgbuf;
  struct msgbuf *oslog_streambufp __attribute__((used)) = &oslog_stream_buf;
  
  // List entries for keeping track of the streaming buffer
  static oslog_stream_buf_entry_t oslog_stream_buf_entries;
  
  #define OSLOG_NUM_STREAM_ENTRIES	64
  #define OSLOG_STREAM_BUF_SIZE		4096
  
  int	oslog_open = 0;
  int	os_log_wakeup = 0;
  int	oslog_stream_open = 0;
  int	oslog_stream_buf_size = OSLOG_STREAM_BUF_SIZE;
  int	oslog_stream_num_entries = OSLOG_NUM_STREAM_ENTRIES;
  
  /* oslogsoftc only valid while oslog_open=1 */
  struct oslogsoftc {
  	int	sc_state;		/* see above for possibilities */
  	struct	selinfo sc_selp;	/* thread waiting for select */
  	int	sc_pgid;		/* process/group for async I/O */
  } oslogsoftc;
  
  struct oslog_streamsoftc {
  	int	sc_state;		/* see above for possibilities */
  	struct	selinfo sc_selp;	/* thread waiting for select */
  	int	sc_pgid;		/* process/group for async I/O */
  } oslog_streamsoftc;
  
  STAILQ_HEAD(, oslog_stream_buf_entry_s) oslog_stream_free_head =
  		STAILQ_HEAD_INITIALIZER(oslog_stream_free_head);
  STAILQ_HEAD(, oslog_stream_buf_entry_s) oslog_stream_buf_head =
  		STAILQ_HEAD_INITIALIZER(oslog_stream_buf_head);
  
  /* defined in osfmk/kern/printf.c  */
  extern void oslog_lock_init(void);
  extern void bsd_log_lock(void);
  extern void bsd_log_unlock(void);
  
  /* defined for osfmk/kern/printf.c */
  void bsd_log_init(void);
  
  /*
   * Ideally this file would define this lock, but bsd doesn't have the definition
   * for lock groups.
   */
  decl_lck_spin_data(extern, oslog_stream_lock)
  
  /* XXX wants a linker set so these can be static */
  extern d_open_t         logopen;
  extern d_close_t        logclose;
  extern d_read_t         logread;
  extern d_ioctl_t        logioctl;
  extern d_select_t       logselect;
  
  /* XXX wants a linker set so these can be static */
  extern d_open_t         oslogopen;
  extern d_close_t        oslogclose;
  extern d_select_t       oslogselect;
  extern d_ioctl_t        oslogioctl;
  
  /* XXX wants a linker set so these can be static */
  extern d_open_t         oslog_streamopen;
  extern d_close_t        oslog_streamclose;
  extern d_read_t         oslog_streamread;
  extern d_ioctl_t        oslog_streamioctl;
  extern d_select_t       oslog_streamselect;
  
  void oslog_init(void);
  void oslog_setsize(int size);
  void oslog_streamwrite_locked(firehose_tracepoint_id_u ftid,
  		uint64_t stamp, const void *pubdata, size_t publen);
  void oslog_streamwrite_metadata_locked(oslog_stream_buf_entry_t m_entry);
  static oslog_stream_buf_entry_t oslog_stream_find_free_buf_entry_locked(void);
  static void oslog_streamwrite_append_bytes(const char *buffer, int buflen);
  
  /*
   * Serialize log access.  Note that the log can be written at interrupt level,
   * so any log manipulations that can be done from, or affect, another processor
   * at interrupt level must be guarded with a spin lock.
   */
  
  #define	LOG_LOCK() bsd_log_lock()
  #define	LOG_UNLOCK() bsd_log_unlock()
  
  #if DEBUG
  #define LOG_SETSIZE_DEBUG(x...) kprintf(x)
  #else
  #define LOG_SETSIZE_DEBUG(x...) do { } while(0)
  #endif
  
  static int sysctl_kern_msgbuf(struct sysctl_oid *oidp,
  	void *arg1, int arg2, struct sysctl_req *req);
  
  /*ARGSUSED*/
  int
  logopen(__unused dev_t dev, __unused int flags, __unused int mode, struct proc *p)
  {
  	LOG_LOCK();
  	if (log_open) {
  		LOG_UNLOCK();
  		return (EBUSY);
  	}
  	if (atm_get_diagnostic_config() & ATM_ENABLE_LEGACY_LOGGING) {
  		logsoftc.sc_mbp = msgbufp;
  	} else {
  		/*
  		 * Support for messagetracer (kern_asl_msg())
  		 * In this mode, /dev/klog exports only ASL-formatted messages
  		 * written into aslbufp via vaddlog().
  		 */
  		logsoftc.sc_mbp = aslbufp;
  	}
  	logsoftc.sc_pgid = p->p_pid;		/* signal process only */
  	log_open = 1;
  
  	LOG_UNLOCK();
  
  	return (0);
  }
  
  /*ARGSUSED*/
  int
  logclose(__unused dev_t dev, __unused int flag, __unused int devtype, __unused struct proc *p)
  {
  	LOG_LOCK();
  	logsoftc.sc_state &= ~(LOG_NBIO | LOG_ASYNC);
  	selwakeup(&logsoftc.sc_selp);
  	selthreadclear(&logsoftc.sc_selp);
  	log_open = 0;
  	LOG_UNLOCK();
  	return (0);
  }
  
  
  int
  oslogopen(__unused dev_t dev, __unused int flags, __unused int mode, struct proc *p)
  {
  	LOG_LOCK();
  	if (oslog_open) {
  		LOG_UNLOCK();
  		return(EBUSY);
  	}
  	oslogsoftc.sc_pgid = p->p_pid;		/* signal process only */
  	oslog_open = 1;
  
  	LOG_UNLOCK();
  	return (0);
  }
  
  int
  oslogclose(__unused dev_t dev, __unused int flag, __unused int devtype, __unused struct proc *p)
  {
  	LOG_LOCK();
  	oslogsoftc.sc_state &= ~(LOG_NBIO | LOG_ASYNC);
  	selwakeup(&oslogsoftc.sc_selp);
  	selthreadclear(&oslogsoftc.sc_selp);
  	oslog_open = 0;
  	LOG_UNLOCK();
  	return (0);
  }
  
  int
  oslog_streamopen(__unused dev_t dev, __unused int flags, __unused int mode, struct proc *p)
  {
  	char *oslog_stream_msg_bufc = NULL;
  	oslog_stream_buf_entry_t entries = NULL;
  
  	lck_spin_lock(&oslog_stream_lock);
  	if (oslog_stream_open) {
  		lck_spin_unlock(&oslog_stream_lock);
  		return EBUSY;
  	}
  	lck_spin_unlock(&oslog_stream_lock);
  
  	// Allocate the stream buffer
  	oslog_stream_msg_bufc = kalloc(oslog_stream_buf_size);
  	if (!oslog_stream_msg_bufc) {
  		return ENOMEM;
  	}
  
  	/* entries to support kernel logging in stream mode */
  	entries = kalloc(oslog_stream_num_entries * sizeof(struct oslog_stream_buf_entry_s));
  	if (!entries) {
  		kfree(oslog_stream_msg_bufc, oslog_stream_buf_size);
  		return ENOMEM;
  	}
  
  	lck_spin_lock(&oslog_stream_lock);
  	if (oslog_stream_open) {
  		lck_spin_unlock(&oslog_stream_lock);
  		kfree(oslog_stream_msg_bufc, oslog_stream_buf_size);
  		kfree(entries, oslog_stream_num_entries * sizeof(struct oslog_stream_buf_entry_s));
  		return EBUSY;
  	}
  
  	assert(oslog_streambufp->msg_bufc == NULL);
  	oslog_streambufp->msg_bufc = oslog_stream_msg_bufc;
  	oslog_streambufp->msg_size = oslog_stream_buf_size;
  
  	oslog_stream_buf_entries = entries;
  
  	STAILQ_INIT(&oslog_stream_free_head);
  	STAILQ_INIT(&oslog_stream_buf_head);
  
  	for (int i = 0; i < oslog_stream_num_entries; i++) {
  		oslog_stream_buf_entries[i].type = oslog_stream_link_type_log;
  		oslog_stream_buf_entries[i].offset = 0;
  		oslog_stream_buf_entries[i].size = 0;
  		oslog_stream_buf_entries[i].timestamp = 0;
  		STAILQ_INSERT_TAIL(&oslog_stream_free_head, &oslog_stream_buf_entries[i], buf_entries);
  	}
  
  	/* there should be no pending entries in the stream */
  	assert(STAILQ_EMPTY(&oslog_stream_buf_head));
  	assert(oslog_streambufp->msg_bufx == 0);
  	assert(oslog_streambufp->msg_bufr == 0);
  
  	oslog_streambufp->msg_bufx = 0;
  	oslog_streambufp->msg_bufr = 0;
  	oslog_streamsoftc.sc_pgid = p->p_pid; /* signal process only */
  	oslog_stream_open = 1;
  	lck_spin_unlock(&oslog_stream_lock);
  
  	return 0;
  }
  
  int
  oslog_streamclose(__unused dev_t dev, __unused int flag, __unused int devtype, __unused struct proc *p)
  {
  	oslog_stream_buf_entry_t next_entry = NULL;
  	char *oslog_stream_msg_bufc = NULL;
  	oslog_stream_buf_entry_t entries = NULL;
  
  	lck_spin_lock(&oslog_stream_lock);
  
  	if (oslog_stream_open == 0) {
  		lck_spin_unlock(&oslog_stream_lock);
  		return EBADF;
  	}
  
  	// Consume all log lines
  	while (!STAILQ_EMPTY(&oslog_stream_buf_head)) {
  		next_entry = STAILQ_FIRST(&oslog_stream_buf_head);
  		STAILQ_REMOVE_HEAD(&oslog_stream_buf_head, buf_entries);
  	}
  	oslog_streamwakeup_locked();
  	oslog_streamsoftc.sc_state &= ~(LOG_NBIO | LOG_ASYNC);
  	selwakeup(&oslog_streamsoftc.sc_selp);
  	selthreadclear(&oslog_streamsoftc.sc_selp);
  	oslog_stream_open = 0;
  	oslog_streambufp->msg_bufr = 0;
  	oslog_streambufp->msg_bufx = 0;
  	oslog_stream_msg_bufc = oslog_streambufp->msg_bufc;
  	oslog_streambufp->msg_bufc = NULL;
  	entries = oslog_stream_buf_entries;
  	oslog_stream_buf_entries = NULL;
  	oslog_streambufp->msg_size = 0;
  
  	lck_spin_unlock(&oslog_stream_lock);
  
  	// Free the stream buffer
  	kfree(oslog_stream_msg_bufc, oslog_stream_buf_size);
  	// Free the list entries
  	kfree(entries, oslog_stream_num_entries * sizeof(struct oslog_stream_buf_entry_s));
  
  	return 0;
  }
  
  /*ARGSUSED*/
  int
  logread(__unused dev_t dev, struct uio *uio, int flag)
  {
  	int l;
  	int error = 0;
  	struct msgbuf *mbp = logsoftc.sc_mbp;
  
  	LOG_LOCK();
  	while (mbp->msg_bufr == mbp->msg_bufx) {
  		if (flag & IO_NDELAY) {
  			error = EWOULDBLOCK;
  			goto out;
  		}
  		if (logsoftc.sc_state & LOG_NBIO) {
  			error = EWOULDBLOCK;
  			goto out;
  		}
  		logsoftc.sc_state |= LOG_RDWAIT;
  		LOG_UNLOCK();
  		/*
  		 * If the wakeup is missed 
  		 * then wait for 5 sec and reevaluate 
  		 */
  		if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
  				"klog", 5 * hz)) != 0) {
  			/* if it times out; ignore */
  			if (error != EWOULDBLOCK)
  				return (error);
  		}
  		LOG_LOCK();
  	}
  	logsoftc.sc_state &= ~LOG_RDWAIT;
  
  	while (uio_resid(uio) > 0) {
  		int readpos;
  
  		l = mbp->msg_bufx - mbp->msg_bufr;
  		if (l < 0)
  			l = mbp->msg_size - mbp->msg_bufr;
  		l = min(l, uio_resid(uio));
  		if (l == 0)
  			break;
  
  		readpos = mbp->msg_bufr;
  		LOG_UNLOCK();
  		error = uiomove((caddr_t)&mbp->msg_bufc[readpos], l, uio);
  		LOG_LOCK();
  		if (error)
  			break;
  		mbp->msg_bufr = readpos + l;
  		if (mbp->msg_bufr >= mbp->msg_size)
  			mbp->msg_bufr = 0;
  	}
  out:
  	LOG_UNLOCK();
  	return (error);
  }
  
  /*ARGSUSED*/
  int
  oslog_streamread(__unused dev_t dev, struct uio *uio, int flag)
  {
  	int error = 0;
  	int copy_size = 0;
  	static char logline[FIREHOSE_CHUNK_SIZE];
  
  	lck_spin_lock(&oslog_stream_lock);
  
  	if (!oslog_stream_open) {
  		lck_spin_unlock(&oslog_stream_lock);
  		return EBADF;
  	}
  
  	while (STAILQ_EMPTY(&oslog_stream_buf_head)) {
  		if (flag & IO_NDELAY || oslog_streamsoftc.sc_state & LOG_NBIO) {
  			lck_spin_unlock(&oslog_stream_lock);
  			return EWOULDBLOCK;
  		}
  
  		oslog_streamsoftc.sc_state |= LOG_RDWAIT;
  		wait_result_t wr = assert_wait((event_t)oslog_streambufp,
  			THREAD_INTERRUPTIBLE);
  		if (wr == THREAD_WAITING) {
  			lck_spin_unlock(&oslog_stream_lock);
  			wr = thread_block(THREAD_CONTINUE_NULL);
  			lck_spin_lock(&oslog_stream_lock);
  		}
  
  		switch (wr) {
  			case THREAD_AWAKENED:
  			case THREAD_TIMED_OUT:
  				break;
  			default:
  				lck_spin_unlock(&oslog_stream_lock);
  				return EINTR;
  		}
  	}
  
  	if (!oslog_stream_open) {
  		lck_spin_unlock(&oslog_stream_lock);
  		return EBADF;
  	}
  
  	int logpos = 0;
  	oslog_stream_buf_entry_t read_entry = NULL;
  	uint16_t rec_length;
  
  	read_entry = STAILQ_FIRST(&oslog_stream_buf_head);
  	assert(read_entry != NULL);
  	STAILQ_REMOVE_HEAD(&oslog_stream_buf_head, buf_entries);
  
  	// Copy the timestamp first
  	memcpy(logline + logpos, &read_entry->timestamp, sizeof(uint64_t));
  	logpos += sizeof(uint64_t);
  
  	switch (read_entry->type) {
  		/* Handle metadata messages */
  		case oslog_stream_link_type_metadata:
  		{
  			memcpy(logline + logpos,
  				(read_entry->metadata), read_entry->size);
  			logpos += read_entry->size;
  
  			lck_spin_unlock(&oslog_stream_lock);
  
  			// Free the list entry
  			kfree(read_entry, (sizeof(struct oslog_stream_buf_entry_s) + read_entry->size));
  			break;
  		}
  		/* Handle log messages */
  		case oslog_stream_link_type_log:
  		{
  			/* ensure that the correct read entry was dequeued */
  			assert(read_entry->offset == oslog_streambufp->msg_bufr);
  			rec_length = read_entry->size;
  
  			// If the next log line is contiguous in the buffer, copy it out.
  			if(read_entry->offset + rec_length <= oslog_streambufp->msg_size) {
  				memcpy(logline + logpos,
  					oslog_streambufp->msg_bufc + read_entry->offset, rec_length);
  
  				oslog_streambufp->msg_bufr += rec_length;
  				if (oslog_streambufp->msg_bufr == oslog_streambufp->msg_size) {
  					oslog_streambufp->msg_bufr = 0;
  				}
  				logpos += rec_length;
  			} else {
  				// Otherwise, copy until the end of the buffer, and
  				// copy the remaining bytes starting at index 0.
  				int bytes_left = oslog_streambufp->msg_size - read_entry->offset;
  				memcpy(logline + logpos,
  					oslog_streambufp->msg_bufc + read_entry->offset, bytes_left);
  				logpos += bytes_left;
  				rec_length -= bytes_left;
  
  				memcpy(logline + logpos, (const void *)oslog_streambufp->msg_bufc,
  					rec_length);
  				oslog_streambufp->msg_bufr = rec_length;
  				logpos += rec_length;
  			}
  			assert(oslog_streambufp->msg_bufr < oslog_streambufp->msg_size);
  			STAILQ_INSERT_TAIL(&oslog_stream_free_head, read_entry, buf_entries);
  
  			lck_spin_unlock(&oslog_stream_lock);
  			break;
  		}
  		default:
  		{
  			panic("Got unexpected log entry type: %hhu\n", read_entry->type);
  		}
  	}
  
  	copy_size = min(logpos, uio_resid(uio));
  	if (copy_size != 0) {
  		error = uiomove((caddr_t)logline, copy_size, uio);
  	}
  	(void)hw_atomic_add(&oslog_s_streamed_msgcount, 1);
  
  	return error;
  }
  
  /*ARGSUSED*/
  int
  logselect(__unused dev_t dev, int rw, void * wql, struct proc *p)
  {
  	const struct msgbuf *mbp = logsoftc.sc_mbp;
  
  	switch (rw) {
  
  	case FREAD:
  		LOG_LOCK();	
  		if (mbp->msg_bufr != mbp->msg_bufx) {
  			LOG_UNLOCK();
  			return (1);
  		}
  		selrecord(p, &logsoftc.sc_selp, wql);
  		LOG_UNLOCK();
  		break;
  	}
  	return (0);
  }
  
  int
  oslogselect(__unused dev_t dev, int rw, void * wql, struct proc *p)
  {
  	switch (rw) {
  
  	case FREAD:
  		LOG_LOCK();
  		if (os_log_wakeup) {
  			LOG_UNLOCK();
  			return (1);
  		}
  		selrecord(p, &oslogsoftc.sc_selp, wql);
  		LOG_UNLOCK();
  		break;
  	}
  	return (0);
  }
  
  int
  oslog_streamselect(__unused dev_t dev, int rw, void * wql, struct proc *p)
  {
  	int ret = 0;
  
  	lck_spin_lock(&oslog_stream_lock);
  
  	switch (rw) {
  	case FREAD:
  		if (STAILQ_EMPTY(&oslog_stream_buf_head)) {
  			selrecord(p, &oslog_streamsoftc.sc_selp, wql);
  		} else {
  			ret = 1;
  		}
  		break;
  	}
  
  	lck_spin_unlock(&oslog_stream_lock);
  	return ret;
  }
  
  void
  logwakeup(struct msgbuf *mbp)
  {
  	/* cf. r24974766 & r25201228*/
  	if (oslog_is_safe() == FALSE) {
  		return;
  	}
  
  	LOG_LOCK();	
  	if (!log_open) {
  		LOG_UNLOCK();
  		return;
  	}
  	if (NULL == mbp)
  		mbp = logsoftc.sc_mbp;
  	if (mbp != logsoftc.sc_mbp)
  		goto out;
  	selwakeup(&logsoftc.sc_selp);
  	if (logsoftc.sc_state & LOG_ASYNC) {
  		int pgid = logsoftc.sc_pgid;
  		LOG_UNLOCK();
  		if (pgid < 0)
  			gsignal(-pgid, SIGIO); 
  		else 
  			proc_signal(pgid, SIGIO);
  		LOG_LOCK();
  	}
  	if (logsoftc.sc_state & LOG_RDWAIT) {
  		wakeup((caddr_t)mbp);
  		logsoftc.sc_state &= ~LOG_RDWAIT;
  	}
  out:
  	LOG_UNLOCK();
  }
  
  void
  oslogwakeup(void)
  {
  	LOG_LOCK();
  	if (!oslog_open) {
  		LOG_UNLOCK();
  		return;
  	}
  	selwakeup(&oslogsoftc.sc_selp);
  	os_log_wakeup = 1;
  	LOG_UNLOCK();
  }
  
  static void
  oslog_streamwakeup_locked(void)
  {
  	LCK_SPIN_ASSERT(&oslog_stream_lock, LCK_ASSERT_OWNED);
  	if (!oslog_stream_open) {
  		return;
  	}
  	selwakeup(&oslog_streamsoftc.sc_selp);
  	if (oslog_streamsoftc.sc_state & LOG_RDWAIT) {
  		wakeup((caddr_t)oslog_streambufp);
  		oslog_streamsoftc.sc_state &= ~LOG_RDWAIT;
  	}
  }
  
  void
  oslog_streamwakeup(void)
  {
  	/* cf. r24974766 & r25201228*/
  	if (oslog_is_safe() == FALSE) {
  		return;
  	}
  
  	lck_spin_lock(&oslog_stream_lock);
  	oslog_streamwakeup_locked();
  	lck_spin_unlock(&oslog_stream_lock);
  }
  
  /*ARGSUSED*/
  int
  logioctl(__unused dev_t dev, u_long com, caddr_t data, __unused int flag, __unused struct proc *p)
  {
  	int l;
  	const struct msgbuf *mbp = logsoftc.sc_mbp;
  
  	LOG_LOCK();
  	switch (com) {
  
  	/* return number of characters immediately available */
  	case FIONREAD:
  		l = mbp->msg_bufx - mbp->msg_bufr;
  		if (l < 0)
  			l += mbp->msg_size;
  		*(off_t *)data = l;
  		break;
  
  	case FIONBIO:
  		if (*(int *)data)
  			logsoftc.sc_state |= LOG_NBIO;
  		else
  			logsoftc.sc_state &= ~LOG_NBIO;
  		break;
  
  	case FIOASYNC:
  		if (*(int *)data)
  			logsoftc.sc_state |= LOG_ASYNC;
  		else
  			logsoftc.sc_state &= ~LOG_ASYNC;
  		break;
  
  	case TIOCSPGRP:
  		logsoftc.sc_pgid = *(int *)data;
  		break;
  
  	case TIOCGPGRP:
  		*(int *)data = logsoftc.sc_pgid;
  		break;
  
  	default:
  		LOG_UNLOCK();
  		return (-1);
  	}
  	LOG_UNLOCK();
  	return (0);
  }
  
  /*ARGSUSED*/
  int
  oslogioctl(__unused dev_t dev, u_long com, caddr_t data, __unused int flag, __unused struct proc *p)
  {
  	int ret = 0;
  	mach_vm_size_t buffer_size = (FIREHOSE_BUFFER_KERNEL_CHUNK_COUNT * FIREHOSE_CHUNK_SIZE);
  	firehose_buffer_map_info_t map_info = {0, 0};
  	firehose_buffer_t kernel_firehose_buffer = NULL;
  	mach_vm_address_t user_addr = 0;
  	mach_port_t mem_entry_ptr = MACH_PORT_NULL;
  
  	switch (com) {
  
  	/* return number of characters immediately available */
  
  	case LOGBUFFERMAP:
  		kernel_firehose_buffer = (firehose_buffer_t)kernel_firehose_addr;
  
  		ret = mach_make_memory_entry_64(kernel_map,
  						&buffer_size,
  						(mach_vm_offset_t) kernel_firehose_buffer,
  						( MAP_MEM_VM_SHARE | VM_PROT_READ ),
  						&mem_entry_ptr,
  						MACH_PORT_NULL);
  		if (ret == KERN_SUCCESS) {
  			ret = mach_vm_map_kernel(get_task_map(current_task()),
  					  &user_addr,
  					  buffer_size,
  					  0, /*  mask */
  					  VM_FLAGS_ANYWHERE,
  					  VM_KERN_MEMORY_NONE,
  					  mem_entry_ptr,
  					  0, /* offset */
  					  FALSE, /* copy */
  					  VM_PROT_READ,
  					  VM_PROT_READ,
  					  VM_INHERIT_SHARE);
  		}
  
  		if (ret == KERN_SUCCESS) {
  			map_info.fbmi_addr = (uint64_t) (user_addr);
  			map_info.fbmi_size = buffer_size;
  			bcopy(&map_info, data, sizeof(firehose_buffer_map_info_t));
  		}
  		break;
  	case LOGFLUSHED:
  		LOG_LOCK();
  		os_log_wakeup = 0;
  		LOG_UNLOCK();
  		__firehose_merge_updates(*(firehose_push_reply_t *)(data));
  		break;
  	default:
  		return (-1);
  	}
  	return (0);
  }
  
  /*ARGSUSED*/
  int
  oslog_streamioctl(__unused dev_t dev, u_long com, caddr_t data, __unused int flag, __unused struct proc *p)
  {
  	int err = 0;
  
  	lck_spin_lock(&oslog_stream_lock);
  
  	switch (com) {
  	case FIONBIO:
  		if (data && *(int *)data)
  			oslog_streamsoftc.sc_state |= LOG_NBIO;
  		else
  			oslog_streamsoftc.sc_state &= ~LOG_NBIO;
  		break;
  	case FIOASYNC:
  		if (data && *(int *)data)
  			oslog_streamsoftc.sc_state |= LOG_ASYNC;
  		else
  			oslog_streamsoftc.sc_state &= ~LOG_ASYNC;
  		break;
  	default:
  		err = -1;
  		break;
  	}
  
  	lck_spin_unlock(&oslog_stream_lock);
  	return err;
  }
  
  void
  bsd_log_init(void)
  {
  	/* After this point, we must be ready to accept characters */
  }
  
  void
  oslog_init(void)
  {
  	kern_return_t kr;
  	vm_size_t size = FIREHOSE_BUFFER_KERNEL_CHUNK_COUNT * FIREHOSE_CHUNK_SIZE;
  
  	oslog_lock_init();
  
  	kr = kmem_alloc_flags(kernel_map, &kernel_firehose_addr,
  		size + (2 * PAGE_SIZE), VM_KERN_MEMORY_LOG,
  		KMA_GUARD_FIRST | KMA_GUARD_LAST);
  	if (kr != KERN_SUCCESS) {
  		panic("Failed to allocate memory for firehose logging buffer");
  	}
  	kernel_firehose_addr += PAGE_SIZE;
  	bzero((void *)kernel_firehose_addr, size);
  	/* register buffer with firehose */
  	kernel_firehose_addr = (vm_offset_t)__firehose_buffer_create((size_t *) &size);
  
  	kprintf("oslog_init completed\n");
  }
  
  /*
   * log_putc_locked
   *
   * Decription:	Output a character to the log; assumes the LOG_LOCK() is held
   *		by the caller.
   *
   * Parameters:	c				Character to output
   *
   * Returns:	(void)
   *
   * Notes:	This functions is used for multibyte output to the log; it
   *		should be used preferrentially where possible to ensure that
   *		log entries do not end up interspersed due to preemption or
   *		SMP reentrancy.
   */
  void
  log_putc_locked(struct msgbuf *mbp, char c)
  {
  	mbp->msg_bufc[mbp->msg_bufx++] = c;
  	if (mbp->msg_bufx >= mbp->msg_size)
  		mbp->msg_bufx = 0;
  }
  
  static oslog_stream_buf_entry_t
  oslog_stream_find_free_buf_entry_locked(void)
  {
  	struct msgbuf *mbp;
  	oslog_stream_buf_entry_t buf_entry = NULL;
  
  	LCK_SPIN_ASSERT(&oslog_stream_lock, LCK_ASSERT_OWNED);
  
  	mbp = oslog_streambufp;
  
  	buf_entry = STAILQ_FIRST(&oslog_stream_free_head);
  	if (buf_entry) {
  		STAILQ_REMOVE_HEAD(&oslog_stream_free_head, buf_entries);
  	}
  	else {
  		// If no list elements are available in the free-list,
  		// consume the next log line so we can free up its list element
  		oslog_stream_buf_entry_t prev_entry = NULL;
  
  		buf_entry = STAILQ_FIRST(&oslog_stream_buf_head);
  		while (buf_entry->type == oslog_stream_link_type_metadata) {
  			prev_entry = buf_entry;
  			buf_entry = STAILQ_NEXT(buf_entry, buf_entries);
  		}
  
  		if (prev_entry == NULL) {
  			STAILQ_REMOVE_HEAD(&oslog_stream_buf_head, buf_entries);
  		}
  		else {
  			STAILQ_REMOVE_AFTER(&oslog_stream_buf_head, prev_entry, buf_entries);
  		}
  
  		mbp->msg_bufr += buf_entry->size;
  		oslog_s_dropped_msgcount++;
  		if (mbp->msg_bufr >= mbp->msg_size) {
  			mbp->msg_bufr = (mbp->msg_bufr % mbp->msg_size);
  		}
  	}
  
  	return buf_entry;
  }
  
  void
  oslog_streamwrite_metadata_locked(oslog_stream_buf_entry_t m_entry)
  {
  	LCK_SPIN_ASSERT(&oslog_stream_lock, LCK_ASSERT_OWNED);
  	STAILQ_INSERT_TAIL(&oslog_stream_buf_head, m_entry, buf_entries);
  
  	return;
  }
  
  static void
  oslog_streamwrite_append_bytes(const char *buffer, int buflen)
  {
  	struct msgbuf *mbp;
  
  	LCK_SPIN_ASSERT(&oslog_stream_lock, LCK_ASSERT_OWNED);
  
  	mbp = oslog_streambufp;
  	// Check if we have enough space in the stream buffer to write the data
  	if (mbp->msg_bufx + buflen <= mbp->msg_size) {
  		memcpy((void *)(mbp->msg_bufc + mbp->msg_bufx), buffer, buflen);
  
  		mbp->msg_bufx += buflen;
  		if (mbp->msg_bufx == mbp->msg_size) {
  			mbp->msg_bufx = 0;
  		}
  	} else {
  		// Copy part of the data until the end of the stream
  		int bytes_left = mbp->msg_size - mbp->msg_bufx;
  		memcpy((void *)(mbp->msg_bufc + mbp->msg_bufx), buffer, bytes_left);
  
  		buflen -= bytes_left;
  		buffer += bytes_left;
  
  		// Copy the remainder of the data from the beginning of stream
  		memcpy((void *)mbp->msg_bufc, buffer, buflen);
  		mbp->msg_bufx = buflen;
  	}
  	return;
  }
  
  
  void
  oslog_streamwrite_locked(firehose_tracepoint_id_u ftid,
  		uint64_t stamp, const void *pubdata, size_t publen)
  {
  	struct msgbuf *mbp;
  	int available_space = 0;
  	oslog_stream_buf_entry_t buf_entry = NULL;
  	oslog_stream_buf_entry_t next_entry = NULL;
  
  	uint16_t ft_size = offsetof(struct firehose_tracepoint_s, ft_data);
  	int ft_length = ft_size + publen;
  
  	LCK_SPIN_ASSERT(&oslog_stream_lock, LCK_ASSERT_OWNED);
  
  	mbp = oslog_streambufp;
  	if (ft_length > mbp->msg_size) {
  		(void)hw_atomic_add(&oslog_s_error_count, 1);
  		return;
  	}
  
  	// Ensure that we have a list element for this record
  	buf_entry = oslog_stream_find_free_buf_entry_locked();
  
  	assert(buf_entry != NULL);
  
  	// Ensure that we have space in the ring buffer for the current logline
  	if (mbp->msg_bufr > mbp->msg_bufx) {
  		available_space = mbp->msg_bufr - mbp->msg_bufx;
  	} else {
  		available_space = mbp->msg_size - mbp->msg_bufx + mbp->msg_bufr;
  	}
  	while(ft_length > available_space) {
  		oslog_stream_buf_entry_t prev_entry = NULL;
  
  		next_entry = STAILQ_FIRST(&oslog_stream_buf_head);
  		assert(next_entry != NULL);
  		while (next_entry->type == oslog_stream_link_type_metadata) {
  			prev_entry = next_entry;
  			next_entry = STAILQ_NEXT(next_entry, buf_entries);
  		}
  
  		if (prev_entry == NULL) {
  			STAILQ_REMOVE_HEAD(&oslog_stream_buf_head, buf_entries);
  		}
  		else {
  			STAILQ_REMOVE_AFTER(&oslog_stream_buf_head, prev_entry, buf_entries);
  		}
  
  		mbp->msg_bufr += next_entry->size;
  		if (mbp->msg_bufr >= mbp->msg_size) {
  			mbp->msg_bufr = (mbp->msg_bufr % mbp->msg_size);
  		}
  
  		oslog_s_dropped_msgcount++;
  		available_space += next_entry->size;
  
  		STAILQ_INSERT_TAIL(&oslog_stream_free_head, next_entry, buf_entries);
  	}
  
  	assert(ft_length <= available_space);
  
  	// Write the log line and update the list entry for this record
  	buf_entry->offset = mbp->msg_bufx;
  	buf_entry->size = ft_length;
  	buf_entry->timestamp = stamp;
  	buf_entry->type = oslog_stream_link_type_log;
  
  	// Construct a tracepoint
  	struct firehose_tracepoint_s fs = {
  		.ft_thread = thread_tid(current_thread()),
  		.ft_id.ftid_value = ftid.ftid_value,
  		.ft_length = publen
  	};
  
  	oslog_streamwrite_append_bytes((char *)&fs, sizeof(fs));
  	oslog_streamwrite_append_bytes(pubdata, publen);
  
  	assert(mbp->msg_bufr < mbp->msg_size);
  	// Insert the element to the buffer data list
  	STAILQ_INSERT_TAIL(&oslog_stream_buf_head, buf_entry, buf_entries);
  
  	return;
  }
  
  
  
  /*
   * log_putc
   *
   * Decription:	Output a character to the log; assumes the LOG_LOCK() is NOT
   *		held by the caller.
   *
   * Parameters:	c				Character to output
   *
   * Returns:	(void)
   *
   * Notes:	This function is used for single byte output to the log.  It
   *		primarily exists to maintain binary backward compatibility.
   */
  void
  log_putc(char c)
  {
  	int unread_count = 0;
  	LOG_LOCK();
  	log_putc_locked(msgbufp, c);
  	unread_count = msgbufp->msg_bufx - msgbufp->msg_bufr;
  	LOG_UNLOCK();
  
  	if (unread_count < 0)
  		unread_count = 0 - unread_count;
  	if (c == '\n' || unread_count >= (msgbufp->msg_size / 2))
  		logwakeup(msgbufp);
  }
  
  
  /*
   * it is possible to increase the kernel log buffer size by adding
   *   msgbuf=n
   * to the kernel command line, and to read the current size using
   *   sysctl kern.msgbuf
   * If there is no parameter on the kernel command line, the buffer is
   * allocated statically and is CONFIG_MSG_BSIZE characters in size, otherwise
   * memory is dynamically allocated. Memory management must already be up.
   */
  int
  log_setsize(int size)
  {
  	char *new_logdata;
  	int new_logsize, new_bufr, new_bufx;
  	char *old_logdata;
  	int old_logsize, old_bufr, old_bufx;
  	int i, count;
  	char *p, ch;
  
  	if (size > MAX_MSG_BSIZE)
  		return (EINVAL);
  
  	if (size <= 0)
  		return (EINVAL);
  
  	new_logsize = size;
  	if (!(new_logdata = (char*)kalloc(size))) {
  		printf("log_setsize: unable to allocate memory\n");
  		return (ENOMEM);
  	}
  	bzero(new_logdata, new_logsize);
  
  	LOG_LOCK();
  
  	old_logsize = msgbufp->msg_size;
  	old_logdata = msgbufp->msg_bufc;
  	old_bufr = msgbufp->msg_bufr;
  	old_bufx = msgbufp->msg_bufx;
  
  	LOG_SETSIZE_DEBUG("log_setsize(%d): old_logdata %p old_logsize %d old_bufr %d old_bufx %d\n",
  					  size, old_logdata, old_logsize, old_bufr, old_bufx);
  
  	/* start "new_logsize" bytes before the write pointer */
  	if (new_logsize <= old_bufx) {
  		count = new_logsize;
  		p = old_logdata + old_bufx - count;
  	} else {
  		/*
  		 * if new buffer is bigger, copy what we have and let the
  		 * bzero above handle the difference
  		 */
  		count = MIN(new_logsize, old_logsize);
  		p = old_logdata + old_logsize - (count - old_bufx);
  	}
  	for (i = 0; i < count; i++) {
  		if (p >= old_logdata + old_logsize)
  			p = old_logdata;
  
  		ch = *p++;
  		new_logdata[i] = ch;
  	}
  
  	new_bufx = i;
  	if (new_bufx >= new_logsize)
  		new_bufx = 0;
  	msgbufp->msg_bufx = new_bufx;
  
  	new_bufr = old_bufx - old_bufr; /* how much were we trailing bufx by? */
  	if (new_bufr < 0)
  		new_bufr += old_logsize;
  	new_bufr = new_bufx - new_bufr; /* now relative to oldest data in new buffer */
  	if (new_bufr < 0)
  		new_bufr += new_logsize;
  	msgbufp->msg_bufr = new_bufr;
  
  	msgbufp->msg_size = new_logsize;
  	msgbufp->msg_bufc = new_logdata;
  
  	LOG_SETSIZE_DEBUG("log_setsize(%d): new_logdata %p new_logsize %d new_bufr %d new_bufx %d\n",
  					  size, new_logdata, new_logsize, new_bufr, new_bufx);
  
  	LOG_UNLOCK();
  
  	/* this memory is now dead - clear it so that it compresses better
  	   in case of suspend to disk etc. */
  	bzero(old_logdata, old_logsize);
  	if (old_logdata != smsg_bufc) {
  		/* dynamic memory that must be freed */
  		kfree(old_logdata, old_logsize);
  	}
  
  	printf("set system log size to %d bytes\n", new_logsize);
  
  	return 0;
  }
  
  void oslog_setsize(int size)
  {
  	uint16_t scale = 0;
  	// If the size is less than the default stream buffer
  	// do nothing
  	if (size <= OSLOG_STREAM_BUF_SIZE) {
  		return;
  	}
  
  	scale = (uint16_t) (size / OSLOG_STREAM_BUF_SIZE);
  
  	oslog_stream_buf_size = size;
  	oslog_stream_num_entries = scale * OSLOG_NUM_STREAM_ENTRIES;
  	printf("oslog_setsize: new buffer size = %d, new num entries= %d\n", oslog_stream_buf_size, oslog_stream_num_entries);
  }
  
  SYSCTL_PROC(_kern, OID_AUTO, msgbuf,
  	CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, 0, 0,
  	sysctl_kern_msgbuf, "I", "");
  
  static int
  sysctl_kern_msgbuf(struct sysctl_oid *oidp __unused,
  	void *arg1 __unused, int arg2 __unused, struct sysctl_req *req)
  {
  	int old_bufsize, bufsize;
  	int error;
  
  	LOG_LOCK();
  	old_bufsize = bufsize = msgbufp->msg_size;
  	LOG_UNLOCK();
  
  	error = sysctl_io_number(req, bufsize, sizeof(bufsize), &bufsize, NULL);
  	if (error)
  		return (error);
  
  	if (bufsize != old_bufsize) {
  		error = log_setsize(bufsize);
  	}
  
  	return (error);
  }
  
  
  /*
   * This should be called by /sbin/dmesg only via libproc.
   * It returns as much data still in the buffer as possible.
   */
  int
  log_dmesg(user_addr_t buffer, uint32_t buffersize, int32_t * retval)
  {
  	uint32_t i;
  	uint32_t localbuff_size;
  	int error = 0, newl, skip;
  	char *localbuff, *p, *copystart, ch;
  	size_t copysize;
  
  	LOG_LOCK();
  	localbuff_size = (msgbufp->msg_size + 2); /* + '\n' + '\0' */
  	LOG_UNLOCK();
  
  	/* Allocate a temporary non-circular buffer for copyout */
  	if (!(localbuff = (char *)kalloc(localbuff_size))) {
  		printf("log_dmesg: unable to allocate memory\n");
  		return (ENOMEM);
  	}
  
  	/* in between here, the log could become bigger, but that's fine */
  	LOG_LOCK();
  
  	/*
  	 * The message buffer is circular; start at the write pointer, and
  	 * make one loop up to write pointer - 1.
  	 */
  	p = msgbufp->msg_bufc + msgbufp->msg_bufx;
  	for (i = newl = skip = 0; p != msgbufp->msg_bufc + msgbufp->msg_bufx - 1; ++p) {
  		if (p >= msgbufp->msg_bufc + msgbufp->msg_size)
  			p = msgbufp->msg_bufc;
  		ch = *p;
  		/* Skip "\n<.*>" syslog sequences. */
  		if (skip) {
  			if (ch == '>')
  				newl = skip = 0;
  			continue;
  		}
  		if (newl && ch == '<') {
  			skip = 1;
  			continue;
  		}
  		if (ch == '\0')
  			continue;
  		newl = (ch == '\n');
  		localbuff[i++] = ch;
  		/* The original version of this routine contained a buffer
  		 * overflow. At the time, a "small" targeted fix was desired
  		 * so the change below to check the buffer bounds was made.
  		 * TODO: rewrite this needlessly convoluted routine.
  		 */
  		if (i == (localbuff_size - 2))
  			break;
  	}
  	if (!newl)
  		localbuff[i++] = '\n';
  	localbuff[i++] = 0;
  
  	if (buffersize >= i) {
  		copystart = localbuff;
  		copysize = i;
  	} else {
  		copystart = localbuff + i - buffersize;
  		copysize = buffersize;
  	}
  
  	LOG_UNLOCK();
  
  	error = copyout(copystart, buffer, copysize);
  	if (!error)
  		*retval = copysize;
  
  	kfree(localbuff, localbuff_size);
  	return (error);
  }
  
  