xnu-1504.9.17.tar.gz

[apple/xnu.git] / osfmk / mach / message.h

/*
 * Copyright (c) 2000-2005 Apple Computer, 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@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 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.
 */
/*
 * NOTICE: This file was modified by McAfee Research in 2004 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 * Copyright (c) 2005 SPARTA, Inc.
 */
/*
 */
/*
 *	File:	mach/message.h
 *
 *	Mach IPC message and primitive function definitions.
 */

#ifndef	_MACH_MESSAGE_H_
#define _MACH_MESSAGE_H_

#include <stdint.h>
#include <mach/port.h>
#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/machine/vm_types.h>

#include <sys/cdefs.h>

/*
 *  The timeout mechanism uses mach_msg_timeout_t values,
 *  passed by value.  The timeout units are milliseconds.
 *  It is controlled with the MACH_SEND_TIMEOUT
 *  and MACH_RCV_TIMEOUT options.
 */

typedef natural_t mach_msg_timeout_t;

/*
 *  The value to be used when there is no timeout.
 *  (No MACH_SEND_TIMEOUT/MACH_RCV_TIMEOUT option.)
 */

#define MACH_MSG_TIMEOUT_NONE		((mach_msg_timeout_t) 0)

/*
 *  The kernel uses MACH_MSGH_BITS_COMPLEX as a hint.  If it isn't on, it
 *  assumes the body of the message doesn't contain port rights or OOL
 *  data.  The field is set in received messages.  A user task must
 *  use caution in interpreting the body of a message if the bit isn't
 *  on, because the mach_msg_type's in the body might "lie" about the
 *  contents.  If the bit isn't on, but the mach_msg_types
 *  in the body specify rights or OOL data, the behavior is undefined.
 *  (Ie, an error may or may not be produced.)
 *
 *  The value of MACH_MSGH_BITS_REMOTE determines the interpretation
 *  of the msgh_remote_port field.  It is handled like a msgt_name.
 *
 *  The value of MACH_MSGH_BITS_LOCAL determines the interpretation
 *  of the msgh_local_port field.  It is handled like a msgt_name.
 *
 *  MACH_MSGH_BITS() combines two MACH_MSG_TYPE_* values, for the remote
 *  and local fields, into a single value suitable for msgh_bits.
 *
 *  MACH_MSGH_BITS_CIRCULAR should be zero; is is used internally.
 *
 *  The unused bits should be zero and are reserved for the kernel
 *  or for future interface expansion.
 */

#define MACH_MSGH_BITS_ZERO		0x00000000
#define MACH_MSGH_BITS_REMOTE_MASK	0x000000ff
#define MACH_MSGH_BITS_LOCAL_MASK	0x0000ff00
#define MACH_MSGH_BITS_COMPLEX		0x80000000U
#define MACH_MSGH_BITS_USER             0x8000ffffU

#define	MACH_MSGH_BITS_CIRCULAR		0x40000000	/* internal use only */
#define	MACH_MSGH_BITS_USED		0xc000ffffU

#define	MACH_MSGH_BITS_PORTS_MASK				\
		(MACH_MSGH_BITS_REMOTE_MASK|MACH_MSGH_BITS_LOCAL_MASK)

#define MACH_MSGH_BITS(remote, local)				\
		((remote) | ((local) << 8))
#define	MACH_MSGH_BITS_REMOTE(bits)				\
		((bits) & MACH_MSGH_BITS_REMOTE_MASK)
#define	MACH_MSGH_BITS_LOCAL(bits)				\
		(((bits) & MACH_MSGH_BITS_LOCAL_MASK) >> 8)
#define	MACH_MSGH_BITS_PORTS(bits)				\
		((bits) & MACH_MSGH_BITS_PORTS_MASK)
#define	MACH_MSGH_BITS_OTHER(bits)				\
		((bits) &~ MACH_MSGH_BITS_PORTS_MASK)

/*
 *  Every message starts with a message header.
 *  Following the message header, if the message is complex, are a count
 *  of type descriptors and the type descriptors themselves 
 *  (mach_msg_descriptor_t). The size of the message must be specified in 
 *  bytes, and includes the message header, descriptor count, descriptors, 
 *  and inline data.
 *
 *  The msgh_remote_port field specifies the destination of the message.
 *  It must specify a valid send or send-once right for a port.
 *
 *  The msgh_local_port field specifies a "reply port".  Normally,
 *  This field carries a send-once right that the receiver will use
 *  to reply to the message.  It may carry the values MACH_PORT_NULL,
 *  MACH_PORT_DEAD, a send-once right, or a send right.
 *
 *  The msgh_seqno field carries a sequence number associated with the
 *  received-from port.  A port's sequence number is incremented every
 *  time a message is received from it.  In sent messages, the field's
 *  value is ignored.
 *
 *  The msgh_id field is uninterpreted by the message primitives.
 *  It normally carries information specifying the format
 *  or meaning of the message.
 */

typedef unsigned int mach_msg_bits_t;
typedef	natural_t mach_msg_size_t;
typedef integer_t mach_msg_id_t;


#define MACH_MSG_SIZE_NULL (mach_msg_size_t *) 0

typedef unsigned int mach_msg_type_name_t;

#define MACH_MSG_TYPE_MOVE_RECEIVE	16	/* Must hold receive rights */
#define MACH_MSG_TYPE_MOVE_SEND		17	/* Must hold send rights */
#define MACH_MSG_TYPE_MOVE_SEND_ONCE	18	/* Must hold sendonce rights */
#define MACH_MSG_TYPE_COPY_SEND		19	/* Must hold send rights */
#define MACH_MSG_TYPE_MAKE_SEND		20	/* Must hold receive rights */
#define MACH_MSG_TYPE_MAKE_SEND_ONCE	21	/* Must hold receive rights */
#define MACH_MSG_TYPE_COPY_RECEIVE	22	/* Must hold receive rights */

typedef unsigned int mach_msg_copy_options_t;

#define MACH_MSG_PHYSICAL_COPY		0
#define MACH_MSG_VIRTUAL_COPY   	1
#define MACH_MSG_ALLOCATE		2
#define MACH_MSG_OVERWRITE		3
#ifdef  MACH_KERNEL
#define MACH_MSG_KALLOC_COPY_T		4
#endif  /* MACH_KERNEL */

/*
 * In a complex mach message, the mach_msg_header_t is followed by 
 * a descriptor count, then an array of that number of descriptors 
 * (mach_msg_*_descriptor_t). The type field of mach_msg_type_descriptor_t
 * (which any descriptor can be cast to) indicates the flavor of the
 * descriptor.
 *
 * Note that in LP64, the various types of descriptors are no longer all
 * the same size as mach_msg_descriptor_t, so the array cannot be indexed 
 * as expected.
 */

typedef unsigned int mach_msg_descriptor_type_t;

#define MACH_MSG_PORT_DESCRIPTOR 		0
#define MACH_MSG_OOL_DESCRIPTOR  		1
#define MACH_MSG_OOL_PORTS_DESCRIPTOR 		2
#define MACH_MSG_OOL_VOLATILE_DESCRIPTOR  	3

#pragma pack(4)

typedef struct
{
  natural_t			pad1;
  mach_msg_size_t		pad2;
  unsigned int			pad3 : 24;
  mach_msg_descriptor_type_t	type : 8;
} mach_msg_type_descriptor_t;

typedef struct
{
  mach_port_t			name;
#if !(defined(KERNEL) && defined(__LP64__))
// Pad to 8 bytes everywhere except the K64 kernel where mach_port_t is 8 bytes
  mach_msg_size_t		pad1;
#endif
  unsigned int			pad2 : 16;
  mach_msg_type_name_t		disposition : 8;
  mach_msg_descriptor_type_t	type : 8;
#if defined(KERNEL)
  uint32_t          pad_end;
#endif
} mach_msg_port_descriptor_t;

typedef struct
{
  uint32_t			address;
  mach_msg_size_t       	size;
  boolean_t     		deallocate: 8;
  mach_msg_copy_options_t       copy: 8;
  unsigned int     		pad1: 8;
  mach_msg_descriptor_type_t    type: 8;
} mach_msg_ool_descriptor32_t;

typedef struct
{
  uint64_t			address;
  boolean_t     		deallocate: 8;
  mach_msg_copy_options_t       copy: 8;
  unsigned int     		pad1: 8;
  mach_msg_descriptor_type_t    type: 8;
  mach_msg_size_t       	size;
} mach_msg_ool_descriptor64_t;

typedef struct
{
  void*				address;
#if !defined(__LP64__)
  mach_msg_size_t       	size;
#endif
  boolean_t     		deallocate: 8;
  mach_msg_copy_options_t       copy: 8;
  unsigned int     		pad1: 8;
  mach_msg_descriptor_type_t    type: 8;
#if defined(__LP64__)
  mach_msg_size_t       	size;
#endif
#if defined(KERNEL) && !defined(__LP64__)
  uint32_t          pad_end;
#endif
} mach_msg_ool_descriptor_t;

typedef struct
{
  uint32_t			address;
  mach_msg_size_t		count;
  boolean_t     		deallocate: 8;
  mach_msg_copy_options_t       copy: 8;
  mach_msg_type_name_t		disposition : 8;
  mach_msg_descriptor_type_t	type : 8;
} mach_msg_ool_ports_descriptor32_t;

typedef struct
{
  uint64_t			address;
  boolean_t     		deallocate: 8;
  mach_msg_copy_options_t       copy: 8;
  mach_msg_type_name_t		disposition : 8;
  mach_msg_descriptor_type_t	type : 8;
  mach_msg_size_t		count;
} mach_msg_ool_ports_descriptor64_t;

typedef struct
{
  void*				address;
#if !defined(__LP64__)
  mach_msg_size_t		count;
#endif
  boolean_t     		deallocate: 8;
  mach_msg_copy_options_t       copy: 8;
  mach_msg_type_name_t		disposition : 8;
  mach_msg_descriptor_type_t	type : 8;
#if defined(__LP64__)
  mach_msg_size_t		count;
#endif
#if defined(KERNEL) && !defined(__LP64__)
  uint32_t          pad_end;
#endif
} mach_msg_ool_ports_descriptor_t;

/*
 * LP64support - This union definition is not really
 * appropriate in LP64 mode because not all descriptors
 * are of the same size in that environment.
 */
#if defined(__LP64__) && defined(KERNEL)
typedef union
{
  mach_msg_port_descriptor_t		port;
  mach_msg_ool_descriptor32_t		out_of_line;
  mach_msg_ool_ports_descriptor32_t	ool_ports;
  mach_msg_type_descriptor_t		type;
} mach_msg_descriptor_t;
#else
typedef union
{
  mach_msg_port_descriptor_t		port;
  mach_msg_ool_descriptor_t		out_of_line;
  mach_msg_ool_ports_descriptor_t	ool_ports;
  mach_msg_type_descriptor_t		type;
} mach_msg_descriptor_t;
#endif

typedef struct
{
        mach_msg_size_t msgh_descriptor_count;
} mach_msg_body_t;

#define MACH_MSG_BODY_NULL (mach_msg_body_t *) 0
#define MACH_MSG_DESCRIPTOR_NULL (mach_msg_descriptor_t *) 0

typedef	struct 
{
  mach_msg_bits_t	msgh_bits;
  mach_msg_size_t	msgh_size;
  mach_port_t		msgh_remote_port;
  mach_port_t		msgh_local_port;
  mach_msg_size_t 	msgh_reserved;
  mach_msg_id_t		msgh_id;
} mach_msg_header_t;

#define MACH_MSG_NULL (mach_msg_header_t *) 0

typedef struct
{
        mach_msg_header_t       header;
        mach_msg_body_t         body;
} mach_msg_base_t;

typedef	unsigned int mach_msg_trailer_type_t;

#define	MACH_MSG_TRAILER_FORMAT_0	0

typedef	unsigned int mach_msg_trailer_size_t;

typedef struct 
{
  mach_msg_trailer_type_t	msgh_trailer_type;
  mach_msg_trailer_size_t	msgh_trailer_size;
} mach_msg_trailer_t;

typedef struct
{
  mach_msg_trailer_type_t       msgh_trailer_type;
  mach_msg_trailer_size_t       msgh_trailer_size;
  mach_port_seqno_t             msgh_seqno;
} mach_msg_seqno_trailer_t;

typedef struct
{
  unsigned int			val[2];
} security_token_t;

typedef struct 
{
  mach_msg_trailer_type_t	msgh_trailer_type;
  mach_msg_trailer_size_t	msgh_trailer_size;
  mach_port_seqno_t		msgh_seqno;
  security_token_t		msgh_sender;
} mach_msg_security_trailer_t;

/*
 * The audit token is an opaque token which identifies
 * Mach tasks and senders of Mach messages as subjects
 * to the BSM audit system.  Only the appropriate BSM
 * library routines should be used to interpret the
 * contents of the audit token as the representation
 * of the subject identity within the token may change
 * over time.
 */
typedef struct
{
  unsigned int			val[8];
} audit_token_t;

typedef struct 
{
  mach_msg_trailer_type_t	msgh_trailer_type;
  mach_msg_trailer_size_t	msgh_trailer_size;
  mach_port_seqno_t		msgh_seqno;
  security_token_t		msgh_sender;
  audit_token_t			msgh_audit;
} mach_msg_audit_trailer_t;

typedef struct 
{
  mach_msg_trailer_type_t	msgh_trailer_type;
  mach_msg_trailer_size_t	msgh_trailer_size;
  mach_port_seqno_t		msgh_seqno;
  security_token_t		msgh_sender;
  audit_token_t			msgh_audit;
  mach_vm_address_t		msgh_context;
} mach_msg_context_trailer_t;


typedef struct
{
  mach_port_name_t sender;
} msg_labels_t;

/* 
   Trailer type to pass MAC policy label info as a mach message trailer.
   
*/

typedef struct
{
  mach_msg_trailer_type_t       msgh_trailer_type;
  mach_msg_trailer_size_t       msgh_trailer_size;
  mach_port_seqno_t             msgh_seqno;
  security_token_t              msgh_sender;
  audit_token_t                 msgh_audit;
  mach_vm_address_t             msgh_context;
  int				msgh_ad;
  msg_labels_t                  msgh_labels;
} mach_msg_mac_trailer_t;

#define MACH_MSG_TRAILER_MINIMUM_SIZE  sizeof(mach_msg_trailer_t)

/*
 * These values can change from release to release - but clearly
 * code cannot request additional trailer elements one was not
 * compiled to understand.  Therefore, it is safe to use this
 * constant when the same module specified the receive options.
 * Otherwise, you run the risk that the options requested by
 * another module may exceed the local modules notion of
 * MAX_TRAILER_SIZE.
 */
typedef mach_msg_mac_trailer_t mach_msg_max_trailer_t;
#define MAX_TRAILER_SIZE ((mach_msg_size_t)sizeof(mach_msg_max_trailer_t))

/*
 * Legacy requirements keep us from ever updating these defines (even
 * when the format_0 trailers gain new option data fields in the future).
 * Therefore, they shouldn't be used going forward.  Instead, the sizes
 * should be compared against the specific element size requested using
 * REQUESTED_TRAILER_SIZE.
 */
typedef mach_msg_security_trailer_t mach_msg_format_0_trailer_t;

/*typedef mach_msg_mac_trailer_t mach_msg_format_0_trailer_t;
*/

#define MACH_MSG_TRAILER_FORMAT_0_SIZE sizeof(mach_msg_format_0_trailer_t)

#define   KERNEL_SECURITY_TOKEN_VALUE  { {0, 1} }
extern security_token_t KERNEL_SECURITY_TOKEN;

#define   KERNEL_AUDIT_TOKEN_VALUE  { {0, 0, 0, 0, 0, 0, 0, 0} }
extern audit_token_t KERNEL_AUDIT_TOKEN;

typedef	integer_t mach_msg_options_t;

typedef struct
{
  mach_msg_header_t	header;
} mach_msg_empty_send_t;

typedef struct
{
  mach_msg_header_t	header;
  mach_msg_trailer_t	trailer;
} mach_msg_empty_rcv_t;

typedef union
{
  mach_msg_empty_send_t	send;
  mach_msg_empty_rcv_t	rcv;
} mach_msg_empty_t;

#pragma pack()

/* utility to round the message size - will become machine dependent */
#define round_msg(x)	(((mach_msg_size_t)(x) + sizeof (natural_t) - 1) & \
				~(sizeof (natural_t) - 1))

/*
 *  There is no fixed upper bound to the size of Mach messages.
 */

#define	MACH_MSG_SIZE_MAX	((mach_msg_size_t) ~0)

/*
 *  Compatibility definitions, for code written
 *  when there was a msgh_kind instead of msgh_seqno.
 */
#define MACH_MSGH_KIND_NORMAL		0x00000000
#define MACH_MSGH_KIND_NOTIFICATION	0x00000001
#define	msgh_kind			msgh_seqno
#define mach_msg_kind_t			mach_port_seqno_t

typedef natural_t mach_msg_type_size_t;
typedef natural_t mach_msg_type_number_t;

/*
 *  Values received/carried in messages.  Tells the receiver what
 *  sort of port right he now has.
 *
 *  MACH_MSG_TYPE_PORT_NAME is used to transfer a port name
 *  which should remain uninterpreted by the kernel.  (Port rights
 *  are not transferred, just the port name.)
 */

#define MACH_MSG_TYPE_PORT_NONE		0

#define MACH_MSG_TYPE_PORT_NAME		15
#define MACH_MSG_TYPE_PORT_RECEIVE	MACH_MSG_TYPE_MOVE_RECEIVE
#define MACH_MSG_TYPE_PORT_SEND		MACH_MSG_TYPE_MOVE_SEND
#define MACH_MSG_TYPE_PORT_SEND_ONCE	MACH_MSG_TYPE_MOVE_SEND_ONCE

#define MACH_MSG_TYPE_LAST		22		/* Last assigned */

/*
 *  A dummy value.  Mostly used to indicate that the actual value
 *  will be filled in later, dynamically.
 */

#define MACH_MSG_TYPE_POLYMORPHIC	((mach_msg_type_name_t) -1)

/*
 *	Is a given item a port type?
 */

#define MACH_MSG_TYPE_PORT_ANY(x)			\
	(((x) >= MACH_MSG_TYPE_MOVE_RECEIVE) &&		\
	 ((x) <= MACH_MSG_TYPE_MAKE_SEND_ONCE))

#define	MACH_MSG_TYPE_PORT_ANY_SEND(x)			\
	(((x) >= MACH_MSG_TYPE_MOVE_SEND) &&		\
	 ((x) <= MACH_MSG_TYPE_MAKE_SEND_ONCE))

#define	MACH_MSG_TYPE_PORT_ANY_RIGHT(x)			\
	(((x) >= MACH_MSG_TYPE_MOVE_RECEIVE) &&		\
	 ((x) <= MACH_MSG_TYPE_MOVE_SEND_ONCE))

typedef integer_t mach_msg_option_t;

#define MACH_MSG_OPTION_NONE	0x00000000

#define	MACH_SEND_MSG		0x00000001
#define	MACH_RCV_MSG		0x00000002
#define MACH_RCV_LARGE		0x00000004

#define MACH_SEND_TIMEOUT	0x00000010
#define MACH_SEND_INTERRUPT	0x00000040	/* libmach implements */
#define MACH_SEND_CANCEL	0x00000080
#define MACH_SEND_ALWAYS	0x00010000	/* internal use only */
#define MACH_SEND_TRAILER	0x00020000	

#define MACH_RCV_TIMEOUT	0x00000100
#define MACH_RCV_NOTIFY		0x00000200
#define MACH_RCV_INTERRUPT	0x00000400	/* libmach implements */
#define MACH_RCV_OVERWRITE	0x00001000

/* 
 * NOTE: a 0x00------ RCV mask implies to ask for
 * a MACH_MSG_TRAILER_FORMAT_0 with 0 Elements, 
 * which is equivalent to a mach_msg_trailer_t.
 *
 * XXXMAC: unlike the rest of the MACH_RCV_* flags, MACH_RCV_TRAILER_LABELS
 * needs its own private bit since we only calculate its fields when absolutely 
 * required.
 */
#define MACH_RCV_TRAILER_NULL   0
#define MACH_RCV_TRAILER_SEQNO  1
#define MACH_RCV_TRAILER_SENDER 2
#define MACH_RCV_TRAILER_AUDIT  3
#define MACH_RCV_TRAILER_CTX    4
#define MACH_RCV_TRAILER_AV     7
#define MACH_RCV_TRAILER_LABELS 8

#define MACH_RCV_TRAILER_TYPE(x)     (((x) & 0xf) << 28) 
#define MACH_RCV_TRAILER_ELEMENTS(x) (((x) & 0xf) << 24)  
#define MACH_RCV_TRAILER_MASK 	     ((0xff << 24))

#define GET_RCV_ELEMENTS(y) (((y) >> 24) & 0xf)

/* 
 * XXXMAC: note that in the case of MACH_RCV_TRAILER_LABELS, 
 * we just fall through to mach_msg_max_trailer_t.
 * This is correct behavior since mach_msg_max_trailer_t is defined as
 * mac_msg_mac_trailer_t which is used for the LABELS trailer.
 * It also makes things work properly if MACH_RCV_TRAILER_LABELS is ORed 
 * with one of the other options.
 */
#define REQUESTED_TRAILER_SIZE(y) 				\
	((mach_msg_trailer_size_t)				\
	 ((GET_RCV_ELEMENTS(y) == MACH_RCV_TRAILER_NULL) ?	\
	  sizeof(mach_msg_trailer_t) :				\
	  ((GET_RCV_ELEMENTS(y) == MACH_RCV_TRAILER_SEQNO) ?	\
	   sizeof(mach_msg_seqno_trailer_t) :			\
	  ((GET_RCV_ELEMENTS(y) == MACH_RCV_TRAILER_SENDER) ?	\
	   sizeof(mach_msg_security_trailer_t) :		\
	   ((GET_RCV_ELEMENTS(y) == MACH_RCV_TRAILER_AUDIT) ?	\
	    sizeof(mach_msg_audit_trailer_t) :      		\
	    ((GET_RCV_ELEMENTS(y) == MACH_RCV_TRAILER_CTX) ?	\
	     sizeof(mach_msg_context_trailer_t) :      		\
	     ((GET_RCV_ELEMENTS(y) == MACH_RCV_TRAILER_AV) ?	\
	      sizeof(mach_msg_mac_trailer_t) :      		\
	     sizeof(mach_msg_max_trailer_t))))))))

/*
 *  Much code assumes that mach_msg_return_t == kern_return_t.
 *  This definition is useful for descriptive purposes.
 *
 *  See <mach/error.h> for the format of error codes.
 *  IPC errors are system 4.  Send errors are subsystem 0;
 *  receive errors are subsystem 1.  The code field is always non-zero.
 *  The high bits of the code field communicate extra information
 *  for some error codes.  MACH_MSG_MASK masks off these special bits.
 */

typedef kern_return_t mach_msg_return_t;

#define MACH_MSG_SUCCESS		0x00000000


#define	MACH_MSG_MASK			0x00003e00
		/* All special error code bits defined below. */
#define	MACH_MSG_IPC_SPACE		0x00002000
		/* No room in IPC name space for another capability name. */
#define	MACH_MSG_VM_SPACE		0x00001000
		/* No room in VM address space for out-of-line memory. */
#define	MACH_MSG_IPC_KERNEL		0x00000800
		/* Kernel resource shortage handling an IPC capability. */
#define	MACH_MSG_VM_KERNEL		0x00000400
		/* Kernel resource shortage handling out-of-line memory. */

#define MACH_SEND_IN_PROGRESS		0x10000001
		/* Thread is waiting to send.  (Internal use only.) */
#define MACH_SEND_INVALID_DATA		0x10000002
		/* Bogus in-line data. */
#define MACH_SEND_INVALID_DEST		0x10000003
		/* Bogus destination port. */
#define MACH_SEND_TIMED_OUT		0x10000004
		/* Message not sent before timeout expired. */
#define MACH_SEND_INTERRUPTED		0x10000007
		/* Software interrupt. */
#define MACH_SEND_MSG_TOO_SMALL		0x10000008
		/* Data doesn't contain a complete message. */
#define MACH_SEND_INVALID_REPLY		0x10000009
		/* Bogus reply port. */
#define MACH_SEND_INVALID_RIGHT		0x1000000a
		/* Bogus port rights in the message body. */
#define MACH_SEND_INVALID_NOTIFY	0x1000000b
		/* Bogus notify port argument. */
#define MACH_SEND_INVALID_MEMORY	0x1000000c
		/* Invalid out-of-line memory pointer. */
#define MACH_SEND_NO_BUFFER		0x1000000d
		/* No message buffer is available. */
#define MACH_SEND_TOO_LARGE		0x1000000e
		/* Send is too large for port */
#define MACH_SEND_INVALID_TYPE		0x1000000f
		/* Invalid msg-type specification. */
#define MACH_SEND_INVALID_HEADER	0x10000010
		/* A field in the header had a bad value. */
#define MACH_SEND_INVALID_TRAILER	0x10000011
		/* The trailer to be sent does not match kernel format. */
#define MACH_SEND_INVALID_RT_OOL_SIZE	0x10000015
		/* compatibility: no longer a returned error */

#define MACH_RCV_IN_PROGRESS		0x10004001
		/* Thread is waiting for receive.  (Internal use only.) */
#define MACH_RCV_INVALID_NAME		0x10004002
		/* Bogus name for receive port/port-set. */
#define MACH_RCV_TIMED_OUT		0x10004003
		/* Didn't get a message within the timeout value. */
#define MACH_RCV_TOO_LARGE		0x10004004
		/* Message buffer is not large enough for inline data. */
#define MACH_RCV_INTERRUPTED		0x10004005
		/* Software interrupt. */
#define MACH_RCV_PORT_CHANGED		0x10004006
		/* compatibility: no longer a returned error */
#define MACH_RCV_INVALID_NOTIFY		0x10004007
		/* Bogus notify port argument. */
#define MACH_RCV_INVALID_DATA		0x10004008
		/* Bogus message buffer for inline data. */
#define MACH_RCV_PORT_DIED		0x10004009
		/* Port/set was sent away/died during receive. */
#define	MACH_RCV_IN_SET			0x1000400a
		/* compatibility: no longer a returned error */
#define	MACH_RCV_HEADER_ERROR		0x1000400b
		/* Error receiving message header.  See special bits. */
#define	MACH_RCV_BODY_ERROR		0x1000400c
		/* Error receiving message body.  See special bits. */
#define	MACH_RCV_INVALID_TYPE		0x1000400d
		/* Invalid msg-type specification in scatter list. */
#define	MACH_RCV_SCATTER_SMALL		0x1000400e
		/* Out-of-line overwrite region is not large enough */
#define MACH_RCV_INVALID_TRAILER	0x1000400f
		/* trailer type or number of trailer elements not supported */
#define MACH_RCV_IN_PROGRESS_TIMED      0x10004011
                /* Waiting for receive with timeout. (Internal use only.) */


__BEGIN_DECLS

/*
 *	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 silently (trap version does not restart).
 *
 *		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.
 */

extern mach_msg_return_t	mach_msg_overwrite(
					mach_msg_header_t *msg,
					mach_msg_option_t option,
					mach_msg_size_t send_size,
					mach_msg_size_t rcv_size,
					mach_port_name_t rcv_name,
					mach_msg_timeout_t timeout,
					mach_port_name_t notify,
					mach_msg_header_t *rcv_msg,
					mach_msg_size_t rcv_limit);

#ifndef	KERNEL

/*
 *	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 silently (trap version does not restart).
 */
extern mach_msg_return_t	mach_msg(
					mach_msg_header_t *msg,
					mach_msg_option_t option,
					mach_msg_size_t send_size,
					mach_msg_size_t rcv_size,
					mach_port_name_t rcv_name,
					mach_msg_timeout_t timeout,
					mach_port_name_t notify);

#elif defined(MACH_KERNEL_PRIVATE)

extern mach_msg_return_t	mach_msg_receive_results(void);

#endif	/* KERNEL */

__END_DECLS

#endif	/* _MACH_MESSAGE_H_ */