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[apple/xnu.git] / bsd / sys / aio.h

/*
 * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This 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 OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* 
 *	File:	sys/aio.h
 *	Author:	Umesh Vaishampayan [umeshv@apple.com]
 *			05-Feb-2003	umeshv	Created.
 *
 *	Header file for POSIX Asynchronous IO APIs
 *
 */ 

#ifndef _SYS_AIO_H_
#define	_SYS_AIO_H_

#include <sys/signal.h>

struct aiocb {
	int					aio_fildes;		/* File descriptor */
	off_t				aio_offset;		/* File offset */
	volatile void		*aio_buf;		/* Location of buffer */
	size_t				aio_nbytes;		/* Length of transfer */
	int					aio_reqprio;	/* Request priority offset */
	struct sigevent		aio_sigevent;	/* Signal number and value */
	int					aio_lio_opcode;	/* Operation to be performed */
};

/*
 * aio_cancel() return values
 */

/*
 * none of the requested operations could be canceled since they are
 * already complete.
 */
#define	AIO_ALLDONE			0x1

/* all requested operations have been canceled */
#define	AIO_CANCELED		0x2

/*
 * some of the requested operations could not be canceled since
 * they are in progress
 */
#define	AIO_NOTCANCELED		0x4


/*
 * lio_listio operation options
 */

#define	LIO_NOP			0x0 	/* option indicating that no transfer is requested */
#define	LIO_READ		0x1		/* option requesting a read */
#define	LIO_WRITE		0x2		/* option requesting a write */

/*
 * lio_listio() modes
 */

/*
 * A lio_listio() synchronization operation indicating
 * that the calling thread is to continue execution while
 * the lio_listio() operation is being performed, and no
 * notification is given when the operation is complete
 */
#define	LIO_NOWAIT		0x1

/*
 * A lio_listio() synchronization operation indicating
 * that the calling thread is to suspend until the
 * lio_listio() operation is complete.
 */
#define	LIO_WAIT		0x2

/*
 * Maximum number of operations in single lio_listio call
 */
#define	AIO_LISTIO_MAX		16

/*
 * A aio_fsync() options
 * that the calling thread is to continue execution while
 * the lio_listio() operation is being performed, and no
 * notification is given when the operation is complete
 */

#define	O_SYNC			0x0 	/* queued IO is completed as if by fsync() */
#if 0 /* O_DSYNC - NOT SUPPORTED */
#define	O_DSYNC			0x1		/* queued async IO is completed as if by fdatasync() */
#endif

#ifndef KERNEL
/*
 * Prototypes
 */

/*
 * Attempt to cancel one or more asynchronous I/O requests currently outstanding 
 * against file descriptor fd. The aiocbp argument points to the asynchronous I/O 
 * control block for a particular request to be canceled.  If aiocbp is NULL, then 
 * all outstanding cancelable asynchronous I/O requests against fd shall be canceled.
 */
int		aio_cancel( int fd, 
					struct aiocb * aiocbp );
					
/*
 * Return the error status associated with the aiocb structure referenced by the 
 * aiocbp argument. The error status for an asynchronous I/O operation is the errno 
 * value that would be set by the corresponding read(), write(),  or fsync()
 * operation.  If the operation has not yet completed, then the error status shall 
 * be equal to [EINPROGRESS].
 */
int		aio_error( const struct aiocb * aiocbp );

/*
 * Asynchronously force all I/O operations associated with the file indicated by 
 * the file descriptor aio_fildes member of the aiocb structure referenced by the 
 * aiocbp argument and queued at the time of the call to aio_fsync() to the 
 * synchronized I/O completion state.  The function call shall return when the
 * synchronization request has been initiated or queued.  op O_SYNC is the only
 * supported opertation at this time.
 * The aiocbp argument refers to an asynchronous I/O control block. The aiocbp 
 * value may be used as an argument to aio_error() and aio_return() in order to 
 * determine the error status and return status, respectively, of the asynchronous 
 * operation while it is proceeding.  When the request is queued, the error status 
 * for the operation is [EINPROGRESS]. When all data has been successfully 
 * transferred, the error status shall be reset to reflect the success or failure 
 * of the operation.
 */
int		aio_fsync( int op, 
				   struct aiocb * aiocbp );
				   
/*
 * Read aiocbp->aio_nbytes from the file associated with aiocbp->aio_fildes into 
 * the buffer pointed to by aiocbp->aio_buf.  The function call shall return when 
 * the read request has been initiated or queued.
 * The aiocbp value may be used as an argument to aio_error() and aio_return() in 
 * order to determine the error status and return status, respectively, of the 
 * asynchronous operation while it is proceeding. If an error condition is 
 * encountered during queuing, the function call shall return without having 
 * initiated or queued the request. The requested operation takes place at the 
 * absolute position in the file as given by aio_offset, as if lseek() were called 
 * immediately prior to the operation with an offset equal to aio_offset and a 
 * whence equal to SEEK_SET.  After a successful call to enqueue an asynchronous 
 * I/O operation, the value of the file offset for the file is unspecified.
 */
int		aio_read( struct aiocb * aiocbp );

/*
 * Return the return status associated with the aiocb structure referenced by 
 * the aiocbp argument.  The return status for an asynchronous I/O operation is 
 * the value that would be returned by the corresponding read(), write(), or 
 * fsync() function call.  If the error status for the operation is equal to 
 * [EINPROGRESS], then the return status for the operation is undefined.  The 
 * aio_return() function may be called exactly once to retrieve the return status 
 * of a given asynchronous operation; thereafter, if the same aiocb structure 
 * is used in a call to aio_return() or aio_error(), an error may be returned. 
 * When the aiocb structure referred to by aiocbp is used to submit another
 * asynchronous operation, then aio_return() may be successfully used to 
 * retrieve the return status of that operation.
 */
ssize_t	aio_return( struct aiocb * aiocbp );

/*
 * Suspend the calling thread until at least one of the asynchronous I/O 
 * operations referenced by the aiocblist argument has completed, until a signal 
 * interrupts the function, or, if timeout is not NULL, until the time 
 * interval specified by timeout has passed.  If any of the aiocb structures 
 * in the aiocblist correspond to completed asynchronous I/O operations (that is, 
 * the error status for the operation is not equal to [EINPROGRESS]) at the 
 * time of the call, the function shall return without suspending the calling 
 * thread.  The aiocblist argument is an array of pointers to asynchronous I/O 
 * control blocks.  The nent argument indicates the number of elements in the 
 * array.  Each aiocb structure pointed to has been used in initiating an 
 * asynchronous I/O request via aio_read(), aio_write(), or lio_listio(). This 
 * array may contain NULL pointers, which are ignored.
 */
int		aio_suspend( const struct aiocb *const aiocblist[], 
					 int nent,
	 				 const struct timespec * timeoutp );
	 				 
/*
 * Write aiocbp->aio_nbytes to the file associated with aiocbp->aio_fildes from 
 * the buffer pointed to by aiocbp->aio_buf.  The function shall return when the 
 * write request has been initiated or, at a minimum, queued.
 * The aiocbp argument may be used as an argument to aio_error() and aio_return() 
 * in order to determine the error status and return status, respectively, of the 
 * asynchronous operation while it is proceeding.
 */
int		aio_write( struct aiocb * aiocbp );

/*
 * Initiate a list of I/O requests with a single function call.  The mode 
 * argument takes one of the values LIO_WAIT or LIO_NOWAIT and determines whether 
 * the function returns when the I/O operations have been completed, or as soon 
 * as the operations have been queued.  If the mode argument is LIO_WAIT, the 
 * function shall wait until all I/O is complete and the sig argument shall be 
 * ignored. 
 * If the mode argument is LIO_NOWAIT, the function shall return immediately, and 
 * asynchronous notification shall occur, according to the sig argument, when all 
 * the I/O operations complete.  If sig is NULL, then no asynchronous notification
 * shall occur.
 */
int		lio_listio( int mode, 
					struct aiocb *const aiocblist[],
	 				int nent, 
	 				struct sigevent *sigp );
#endif /* KERNEL */
#endif /* _SYS_AIO_H_ */