xnu-6153.141.1.tar.gz

[apple/xnu.git] / libsyscall / mach / mach_msg.c

/*
 * Copyright (c) 1999-2013 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
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 *
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 */
/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */

#include <stdlib.h>
#include <mach/mach.h>
#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/message.h>
#include <mach/mig_errors.h>
#include <mach/vm_statistics.h>
#include <TargetConditionals.h>

extern int proc_importance_assertion_begin_with_msg(mach_msg_header_t * msg, mach_msg_trailer_t * trailer, uint64_t * assertion_handlep);
extern int proc_importance_assertion_complete(uint64_t assertion_handle);

#define MACH_MSG_TRAP(msg, opt, ssize, rsize, rname, to, not) \
	 mach_msg_trap((msg), (opt), (ssize), (rsize), (rname), (to), (not))

#define LIBMACH_OPTIONS (MACH_SEND_INTERRUPT|MACH_RCV_INTERRUPT)

/*
 *	Routine:	mach_msg
 *	Purpose:
 *		Send and/or receive a message.  If the message operation
 *		is interrupted, and the user did not request an indication
 *		of that fact, then restart the appropriate parts of the
 *              operation.
 */
mach_msg_return_t
mach_msg(msg, option, send_size, rcv_size, rcv_name, timeout, notify)
mach_msg_header_t *msg;
mach_msg_option_t option;
mach_msg_size_t send_size;
mach_msg_size_t rcv_size;
mach_port_t rcv_name;
mach_msg_timeout_t timeout;
mach_port_t notify;
{
	mach_msg_return_t mr;

	/*
	 * Consider the following cases:
	 *	1) Errors in pseudo-receive (eg, MACH_SEND_INTERRUPTED
	 *	plus special bits).
	 *	2) Use of MACH_SEND_INTERRUPT/MACH_RCV_INTERRUPT options.
	 *	3) RPC calls with interruptions in one/both halves.
	 *
	 * We refrain from passing the option bits that we implement
	 * to the kernel.  This prevents their presence from inhibiting
	 * the kernel's fast paths (when it checks the option value).
	 */

	mr = MACH_MSG_TRAP(msg, option & ~LIBMACH_OPTIONS,
	    send_size, rcv_size, rcv_name,
	    timeout, notify);
	if (mr == MACH_MSG_SUCCESS) {
		return MACH_MSG_SUCCESS;
	}

	if ((option & MACH_SEND_INTERRUPT) == 0) {
		while (mr == MACH_SEND_INTERRUPTED) {
			mr = MACH_MSG_TRAP(msg,
			    option & ~LIBMACH_OPTIONS,
			    send_size, rcv_size, rcv_name,
			    timeout, notify);
		}
	}

	if ((option & MACH_RCV_INTERRUPT) == 0) {
		while (mr == MACH_RCV_INTERRUPTED) {
			mr = MACH_MSG_TRAP(msg,
			    option & ~(LIBMACH_OPTIONS | MACH_SEND_MSG),
			    0, rcv_size, rcv_name,
			    timeout, notify);
		}
	}

	return mr;
}

/*
 *	Routine:	mach_msg_overwrite
 *	Purpose:
 *		Send and/or receive a message.  If the message operation
 *		is interrupted, and the user did not request an indication
 *		of that fact, then restart the appropriate parts of the
 *              operation.
 *
 *		Distinct send and receive buffers may be specified.  If
 *		no separate receive buffer is specified, the msg parameter
 *		will be used for both send and receive operations.
 *
 *		In addition to a distinct receive buffer, that buffer may
 *		already contain scatter control information to direct the
 *		receiving of the message.
 */
mach_msg_return_t
mach_msg_overwrite(msg, option, send_size, rcv_limit, rcv_name, timeout,
    notify, rcv_msg, rcv_scatter_size)
mach_msg_header_t *msg;
mach_msg_option_t option;
mach_msg_size_t send_size;
mach_msg_size_t rcv_limit;
mach_port_t rcv_name;
mach_msg_timeout_t timeout;
mach_port_t notify;
mach_msg_header_t *rcv_msg;
mach_msg_size_t rcv_scatter_size;
{
	mach_msg_return_t mr;

	/*
	 * Consider the following cases:
	 *	1) Errors in pseudo-receive (eg, MACH_SEND_INTERRUPTED
	 *	plus special bits).
	 *	2) Use of MACH_SEND_INTERRUPT/MACH_RCV_INTERRUPT options.
	 *	3) RPC calls with interruptions in one/both halves.
	 *
	 * We refrain from passing the option bits that we implement
	 * to the kernel.  This prevents their presence from inhibiting
	 * the kernel's fast paths (when it checks the option value).
	 */

	mr = mach_msg_overwrite_trap(msg, option & ~LIBMACH_OPTIONS,
	    send_size, rcv_limit, rcv_name,
	    timeout, notify, rcv_msg, rcv_scatter_size);
	if (mr == MACH_MSG_SUCCESS) {
		return MACH_MSG_SUCCESS;
	}

	if ((option & MACH_SEND_INTERRUPT) == 0) {
		while (mr == MACH_SEND_INTERRUPTED) {
			mr = mach_msg_overwrite_trap(msg,
			    option & ~LIBMACH_OPTIONS,
			    send_size, rcv_limit, rcv_name,
			    timeout, notify, rcv_msg, rcv_scatter_size);
		}
	}

	if ((option & MACH_RCV_INTERRUPT) == 0) {
		while (mr == MACH_RCV_INTERRUPTED) {
			mr = mach_msg_overwrite_trap(msg,
			    option & ~(LIBMACH_OPTIONS | MACH_SEND_MSG),
			    0, rcv_limit, rcv_name,
			    timeout, notify, rcv_msg, rcv_scatter_size);
		}
	}

	return mr;
}


mach_msg_return_t
mach_msg_send(mach_msg_header_t *msg)
{
	return mach_msg(msg, MACH_SEND_MSG,
	           msg->msgh_size, 0, MACH_PORT_NULL,
	           MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
}

mach_msg_return_t
mach_msg_receive(mach_msg_header_t *msg)
{
	return mach_msg(msg, MACH_RCV_MSG,
	           0, msg->msgh_size, msg->msgh_local_port,
	           MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
}


static void
mach_msg_destroy_port(mach_port_t port, mach_msg_type_name_t type)
{
	if (MACH_PORT_VALID(port)) {
		switch (type) {
		case MACH_MSG_TYPE_MOVE_SEND:
		case MACH_MSG_TYPE_MOVE_SEND_ONCE:
			/* destroy the send/send-once right */
			(void) mach_port_deallocate(mach_task_self_, port);
			break;

		case MACH_MSG_TYPE_MOVE_RECEIVE:
			/* destroy the receive right */
			(void) mach_port_mod_refs(mach_task_self_, port,
			    MACH_PORT_RIGHT_RECEIVE, -1);
			break;

		case MACH_MSG_TYPE_MAKE_SEND:
			/* create a send right and then destroy it */
			(void) mach_port_insert_right(mach_task_self_, port,
			    port, MACH_MSG_TYPE_MAKE_SEND);
			(void) mach_port_deallocate(mach_task_self_, port);
			break;

		case MACH_MSG_TYPE_MAKE_SEND_ONCE:
			/* create a send-once right and then destroy it */
			(void) mach_port_extract_right(mach_task_self_, port,
			    MACH_MSG_TYPE_MAKE_SEND_ONCE,
			    &port, &type);
			(void) mach_port_deallocate(mach_task_self_, port);
			break;
		}
	}
}

static void
mach_msg_destroy_memory(vm_offset_t addr, vm_size_t size)
{
	if (size != 0) {
		(void) vm_deallocate(mach_task_self_, addr, size);
	}
}


/*
 *	Routine:	mach_msg_destroy
 *	Purpose:
 *		mach_msg_destroy is useful in two contexts.
 *
 *		First, it can deallocate all port rights and
 *		out-of-line memory in a received message.
 *		When a server receives a request it doesn't want,
 *		it needs this functionality.
 *
 *		Second, it can mimic the side-effects of a msg-send
 *		operation.  The effect is as if the message were sent
 *		and then destroyed inside the kernel.  When a server
 *		can't send a reply (because the client died),
 *		it needs this functionality.
 */
void
mach_msg_destroy(mach_msg_header_t *msg)
{
	mach_msg_bits_t mbits = msg->msgh_bits;

	/*
	 *	The msgh_local_port field doesn't hold a port right.
	 *	The receive operation consumes the destination port right.
	 */

	mach_msg_destroy_port(msg->msgh_remote_port, MACH_MSGH_BITS_REMOTE(mbits));
	mach_msg_destroy_port(msg->msgh_voucher_port, MACH_MSGH_BITS_VOUCHER(mbits));

	if (mbits & MACH_MSGH_BITS_COMPLEX) {
		mach_msg_base_t         *base;
		mach_msg_type_number_t  count, i;
		mach_msg_descriptor_t   *daddr;

		base = (mach_msg_base_t *) msg;
		count = base->body.msgh_descriptor_count;

		daddr = (mach_msg_descriptor_t *) (base + 1);
		for (i = 0; i < count; i++) {
			switch (daddr->type.type) {
			case MACH_MSG_PORT_DESCRIPTOR: {
				mach_msg_port_descriptor_t *dsc;

				/*
				 * Destroy port rights carried in the message
				 */
				dsc = &daddr->port;
				mach_msg_destroy_port(dsc->name, dsc->disposition);
				daddr = (mach_msg_descriptor_t *)(dsc + 1);
				break;
			}

			case MACH_MSG_OOL_DESCRIPTOR: {
				mach_msg_ool_descriptor_t *dsc;

				/*
				 * Destroy memory carried in the message
				 */
				dsc = &daddr->out_of_line;
				if (dsc->deallocate) {
					mach_msg_destroy_memory((vm_offset_t)dsc->address,
					    dsc->size);
				}
				daddr = (mach_msg_descriptor_t *)(dsc + 1);
				break;
			}

			case MACH_MSG_OOL_VOLATILE_DESCRIPTOR: {
				mach_msg_ool_descriptor_t *dsc;

				/*
				 * Just skip it.
				 */
				dsc = &daddr->out_of_line;
				daddr = (mach_msg_descriptor_t *)(dsc + 1);
				break;
			}

			case MACH_MSG_OOL_PORTS_DESCRIPTOR: {
				mach_port_t                         *ports;
				mach_msg_ool_ports_descriptor_t     *dsc;
				mach_msg_type_number_t              j;

				/*
				 * Destroy port rights carried in the message
				 */
				dsc = &daddr->ool_ports;
				ports = (mach_port_t *) dsc->address;
				for (j = 0; j < dsc->count; j++, ports++) {
					mach_msg_destroy_port(*ports, dsc->disposition);
				}

				/*
				 * Destroy memory carried in the message
				 */
				if (dsc->deallocate) {
					mach_msg_destroy_memory((vm_offset_t)dsc->address,
					    dsc->count * sizeof(mach_port_t));
				}
				daddr = (mach_msg_descriptor_t *)(dsc + 1);
				break;
			}

			case MACH_MSG_GUARDED_PORT_DESCRIPTOR: {
				mach_msg_guarded_port_descriptor_t *dsc;
				mach_msg_guard_flags_t flags;
				/*
				 * Destroy port right carried in the message
				 */
				dsc = &daddr->guarded_port;
				flags = dsc->flags;
				if ((flags & MACH_MSG_GUARD_FLAGS_UNGUARDED_ON_SEND) == 0) {
					/* Need to unguard before destroying the port */
					mach_port_unguard(mach_task_self_, dsc->name, (uint64_t)dsc->context);
				}
				mach_msg_destroy_port(dsc->name, dsc->disposition);
				daddr = (mach_msg_descriptor_t *)(dsc + 1);
				break;
			}
			}
		}
	}
}

static inline boolean_t
mach_msg_server_is_recoverable_send_error(kern_return_t kr)
{
	switch (kr) {
	case MACH_SEND_INVALID_DEST:
	case MACH_SEND_TIMED_OUT:
	case MACH_SEND_INTERRUPTED:
		return TRUE;
	default:
		/*
		 * Other errors mean that the message may have been partially destroyed
		 * by the kernel, and these can't be recovered and may leak resources.
		 */
		return FALSE;
	}
}

static kern_return_t
mach_msg_server_mig_return_code(mig_reply_error_t *reply)
{
	/*
	 * If the message is complex, it is assumed that the reply was successful,
	 * as the RetCode is where the count of out of line descriptors is.
	 *
	 * If not, we read RetCode.
	 */
	if (reply->Head.msgh_bits & MACH_MSGH_BITS_COMPLEX) {
		return KERN_SUCCESS;
	}
	return reply->RetCode;
}

static void
mach_msg_server_consume_unsent_message(mach_msg_header_t *hdr)
{
	/* mach_msg_destroy doesn't handle the local port */
	mach_port_t port = hdr->msgh_local_port;
	if (MACH_PORT_VALID(port)) {
		switch (MACH_MSGH_BITS_LOCAL(hdr->msgh_bits)) {
		case MACH_MSG_TYPE_MOVE_SEND:
		case MACH_MSG_TYPE_MOVE_SEND_ONCE:
			/* destroy the send/send-once right */
			(void) mach_port_deallocate(mach_task_self_, port);
			hdr->msgh_local_port = MACH_PORT_NULL;
			break;
		}
	}
	mach_msg_destroy(hdr);
}

/*
 *	Routine:	mach_msg_server_once
 *	Purpose:
 *		A simple generic server function.  It allows more flexibility
 *		than mach_msg_server by processing only one message request
 *		and then returning to the user.  Note that more in the way
 *              of error codes are returned to the user; specifically, any
 *              failing error from mach_msg calls will be returned
 *		(though errors from the demux routine or the routine it
 *		calls will not be).
 */
mach_msg_return_t
mach_msg_server_once(
	boolean_t (*demux)(mach_msg_header_t *, mach_msg_header_t *),
	mach_msg_size_t max_size,
	mach_port_t rcv_name,
	mach_msg_options_t options)
{
	mig_reply_error_t *bufRequest, *bufReply;
	mach_msg_size_t request_size;
	mach_msg_size_t request_alloc;
	mach_msg_size_t trailer_alloc;
	mach_msg_size_t reply_alloc;
	mach_msg_return_t mr;
	kern_return_t kr;
	mach_port_t self = mach_task_self_;
	voucher_mach_msg_state_t old_state = VOUCHER_MACH_MSG_STATE_UNCHANGED;

	options &= ~(MACH_SEND_MSG | MACH_RCV_MSG | MACH_RCV_VOUCHER);

	trailer_alloc = REQUESTED_TRAILER_SIZE(options);
	request_alloc = (mach_msg_size_t)round_page(max_size + trailer_alloc);

	request_size = (options & MACH_RCV_LARGE) ?
	    request_alloc : max_size + trailer_alloc;

	reply_alloc = (mach_msg_size_t)round_page((options & MACH_SEND_TRAILER) ?
	    (max_size + MAX_TRAILER_SIZE) :
	    max_size);

	kr = vm_allocate(self,
	    (vm_address_t *)&bufReply,
	    reply_alloc,
	    VM_MAKE_TAG(VM_MEMORY_MACH_MSG) | TRUE);
	if (kr != KERN_SUCCESS) {
		return kr;
	}

	for (;;) {
		mach_msg_size_t new_request_alloc;

		kr = vm_allocate(self,
		    (vm_address_t *)&bufRequest,
		    request_alloc,
		    VM_MAKE_TAG(VM_MEMORY_MACH_MSG) | TRUE);
		if (kr != KERN_SUCCESS) {
			vm_deallocate(self,
			    (vm_address_t)bufReply,
			    reply_alloc);
			return kr;
		}

		mr = mach_msg(&bufRequest->Head, MACH_RCV_MSG | MACH_RCV_VOUCHER | options,
		    0, request_size, rcv_name,
		    MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);

		if (!((mr == MACH_RCV_TOO_LARGE) && (options & MACH_RCV_LARGE))) {
			break;
		}

		new_request_alloc = (mach_msg_size_t)round_page(bufRequest->Head.msgh_size +
		    trailer_alloc);
		vm_deallocate(self,
		    (vm_address_t) bufRequest,
		    request_alloc);
		request_size = request_alloc = new_request_alloc;
	}

	if (mr == MACH_MSG_SUCCESS) {
		/* we have a request message */

		old_state = voucher_mach_msg_adopt(&bufRequest->Head);

		(void) (*demux)(&bufRequest->Head, &bufReply->Head);

		switch (mach_msg_server_mig_return_code(bufReply)) {
		case KERN_SUCCESS:
			break;
		case MIG_NO_REPLY:
			bufReply->Head.msgh_remote_port = MACH_PORT_NULL;
			break;
		default:
			/*
			 * destroy the request - but not the reply port
			 * (MIG moved it into the bufReply).
			 */
			bufRequest->Head.msgh_remote_port = MACH_PORT_NULL;
			mach_msg_destroy(&bufRequest->Head);
		}

		/*
		 *	We don't want to block indefinitely because the client
		 *	isn't receiving messages from the reply port.
		 *	If we have a send-once right for the reply port, then
		 *	this isn't a concern because the send won't block.
		 *	If we have a send right, we need to use MACH_SEND_TIMEOUT.
		 *	To avoid falling off the kernel's fast RPC path unnecessarily,
		 *	we only supply MACH_SEND_TIMEOUT when absolutely necessary.
		 */
		if (bufReply->Head.msgh_remote_port != MACH_PORT_NULL) {
			mr = mach_msg(&bufReply->Head,
			    (MACH_MSGH_BITS_REMOTE(bufReply->Head.msgh_bits) ==
			    MACH_MSG_TYPE_MOVE_SEND_ONCE) ?
			    MACH_SEND_MSG | options :
			    MACH_SEND_MSG | MACH_SEND_TIMEOUT | options,
			    bufReply->Head.msgh_size, 0, MACH_PORT_NULL,
			    MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);

			if (mach_msg_server_is_recoverable_send_error(mr)) {
				mach_msg_server_consume_unsent_message(&bufReply->Head);
				mr = MACH_MSG_SUCCESS;
			}
		}
	}

	voucher_mach_msg_revert(old_state);

	(void)vm_deallocate(self,
	    (vm_address_t) bufRequest,
	    request_alloc);
	(void)vm_deallocate(self,
	    (vm_address_t) bufReply,
	    reply_alloc);
	return mr;
}

/*
 *	Routine:	mach_msg_server
 *	Purpose:
 *		A simple generic server function.  Note that changes here
 *              should be considered for duplication above.
 */
mach_msg_return_t
mach_msg_server(
	boolean_t (*demux)(mach_msg_header_t *, mach_msg_header_t *),
	mach_msg_size_t max_size,
	mach_port_t rcv_name,
	mach_msg_options_t options)
{
	mig_reply_error_t *bufRequest, *bufReply;
	mach_msg_size_t request_size;
	mach_msg_size_t new_request_alloc;
	mach_msg_size_t request_alloc;
	mach_msg_size_t trailer_alloc;
	mach_msg_size_t reply_alloc;
	mach_msg_return_t mr;
	kern_return_t kr;
	mach_port_t self = mach_task_self_;
	voucher_mach_msg_state_t old_state = VOUCHER_MACH_MSG_STATE_UNCHANGED;
	boolean_t buffers_swapped = FALSE;

	options &= ~(MACH_SEND_MSG | MACH_RCV_MSG | MACH_RCV_VOUCHER);

	reply_alloc = (mach_msg_size_t)round_page((options & MACH_SEND_TRAILER) ?
	    (max_size + MAX_TRAILER_SIZE) : max_size);

	kr = vm_allocate(self,
	    (vm_address_t *)&bufReply,
	    reply_alloc,
	    VM_MAKE_TAG(VM_MEMORY_MACH_MSG) | TRUE);
	if (kr != KERN_SUCCESS) {
		return kr;
	}

	request_alloc = 0;
	trailer_alloc = REQUESTED_TRAILER_SIZE(options);
	new_request_alloc = (mach_msg_size_t)round_page(max_size + trailer_alloc);

	request_size = (options & MACH_RCV_LARGE) ?
	    new_request_alloc : max_size + trailer_alloc;

	for (;;) {
		if (request_alloc < new_request_alloc) {
			request_alloc = new_request_alloc;
			kr = vm_allocate(self,
			    (vm_address_t *)&bufRequest,
			    request_alloc,
			    VM_MAKE_TAG(VM_MEMORY_MACH_MSG) | TRUE);
			if (kr != KERN_SUCCESS) {
				vm_deallocate(self,
				    (vm_address_t)bufReply,
				    reply_alloc);
				return kr;
			}
		}

		mr = mach_msg(&bufRequest->Head, MACH_RCV_MSG | MACH_RCV_VOUCHER | options,
		    0, request_size, rcv_name,
		    MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);

		while (mr == MACH_MSG_SUCCESS) {
			/* we have another request message */

			buffers_swapped = FALSE;
			old_state = voucher_mach_msg_adopt(&bufRequest->Head);
			bufReply->Head = (mach_msg_header_t){};

			(void) (*demux)(&bufRequest->Head, &bufReply->Head);

			switch (mach_msg_server_mig_return_code(bufReply)) {
			case KERN_SUCCESS:
				break;
			case MIG_NO_REPLY:
				bufReply->Head.msgh_remote_port = MACH_PORT_NULL;
				break;
			default:
				/*
				 * destroy the request - but not the reply port
				 * (MIG moved it into the bufReply).
				 */
				bufRequest->Head.msgh_remote_port = MACH_PORT_NULL;
				mach_msg_destroy(&bufRequest->Head);
			}

			/*
			 * We don't want to block indefinitely because the client
			 * isn't receiving messages from the reply port.
			 * If we have a send-once right for the reply port, then
			 * this isn't a concern because the send won't block.
			 * If we have a send right, we need to use MACH_SEND_TIMEOUT.
			 * To avoid falling off the kernel's fast RPC path,
			 * we only supply MACH_SEND_TIMEOUT when absolutely necessary.
			 */
			if (bufReply->Head.msgh_remote_port != MACH_PORT_NULL) {
				if (request_alloc == reply_alloc) {
					mig_reply_error_t *bufTemp;

					mr = mach_msg(
						&bufReply->Head,
						(MACH_MSGH_BITS_REMOTE(bufReply->Head.msgh_bits) ==
						MACH_MSG_TYPE_MOVE_SEND_ONCE) ?
						MACH_SEND_MSG | MACH_RCV_MSG | MACH_RCV_TIMEOUT | MACH_RCV_VOUCHER | options :
						MACH_SEND_MSG | MACH_RCV_MSG | MACH_SEND_TIMEOUT | MACH_RCV_TIMEOUT | MACH_RCV_VOUCHER | options,
						bufReply->Head.msgh_size, request_size, rcv_name,
						MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);

					/* swap request and reply */
					bufTemp = bufRequest;
					bufRequest = bufReply;
					bufReply = bufTemp;
					buffers_swapped = TRUE;
				} else {
					mr = mach_msg_overwrite(
						&bufReply->Head,
						(MACH_MSGH_BITS_REMOTE(bufReply->Head.msgh_bits) ==
						MACH_MSG_TYPE_MOVE_SEND_ONCE) ?
						MACH_SEND_MSG | MACH_RCV_MSG | MACH_RCV_TIMEOUT | MACH_RCV_VOUCHER | options :
						MACH_SEND_MSG | MACH_RCV_MSG | MACH_SEND_TIMEOUT | MACH_RCV_TIMEOUT | MACH_RCV_VOUCHER | options,
						bufReply->Head.msgh_size, request_size, rcv_name,
						MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL,
						&bufRequest->Head, 0);
				}

				/*
				 * Need to destroy the reply msg in case if there was a send timeout or
				 * invalid destination. The reply msg would be swapped with request msg
				 * if buffers_swapped is true, thus destroy request msg instead of
				 * reply msg in such cases.
				 */
				if (mach_msg_server_is_recoverable_send_error(mr)) {
					if (buffers_swapped) {
						mach_msg_server_consume_unsent_message(&bufRequest->Head);
					} else {
						mach_msg_server_consume_unsent_message(&bufReply->Head);
					}
				} else if (mr != MACH_RCV_TIMED_OUT) {
					voucher_mach_msg_revert(old_state);
					old_state = VOUCHER_MACH_MSG_STATE_UNCHANGED;

					continue;
				}
			}
			voucher_mach_msg_revert(old_state);
			old_state = VOUCHER_MACH_MSG_STATE_UNCHANGED;

			mr = mach_msg(&bufRequest->Head, MACH_RCV_MSG | MACH_RCV_VOUCHER | options,
			    0, request_size, rcv_name,
			    MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
		} /* while (mr == MACH_MSG_SUCCESS) */

		if ((mr == MACH_RCV_TOO_LARGE) && (options & MACH_RCV_LARGE)) {
			new_request_alloc = (mach_msg_size_t)round_page(bufRequest->Head.msgh_size +
			    trailer_alloc);
			request_size = new_request_alloc;
			vm_deallocate(self,
			    (vm_address_t) bufRequest,
			    request_alloc);
			continue;
		}

		break;
	} /* for(;;) */

	(void)vm_deallocate(self,
	    (vm_address_t) bufRequest,
	    request_alloc);
	(void)vm_deallocate(self,
	    (vm_address_t) bufReply,
	    reply_alloc);
	return mr;
}

/*
 *	Routine:	mach_msg_server_importance
 *	Purpose:
 *		A simple generic server function which handles importance
 *              promotion assertions for adaptive daemons.
 */
mach_msg_return_t
mach_msg_server_importance(
	boolean_t (*demux)(mach_msg_header_t *, mach_msg_header_t *),
	mach_msg_size_t max_size,
	mach_port_t rcv_name,
	mach_msg_options_t options)
{
	return mach_msg_server(demux, max_size, rcv_name, options);
}

kern_return_t
mach_voucher_deallocate(
	mach_voucher_t  voucher)
{
	return mach_port_deallocate(mach_task_self(), voucher);
}