glibc/rt/aio.h

/* Copyright (C) 1996-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

/*
 * ISO/IEC 9945-1:1996 6.7: Asynchronous Input and Output
 */

#ifndef _AIO_H
#define _AIO_H	1

#include <features.h>
#include <sys/types.h>
#include <bits/types/sigevent_t.h>
#include <bits/sigevent-consts.h>
#include <bits/types/struct_timespec.h>

__BEGIN_DECLS

/* Asynchronous I/O control block.  */
struct aiocb
{
  int aio_fildes;		/* File descriptor.  */
  int aio_lio_opcode;		/* Operation to be performed.  */
  int aio_reqprio;		/* Request priority offset.  */
  volatile void *aio_buf;	/* Location of buffer.  */
  size_t aio_nbytes;		/* Length of transfer.  */
  struct sigevent aio_sigevent;	/* Signal number and value.  */

  /* Internal members.  */
  struct aiocb *__next_prio;
  int __abs_prio;
  int __policy;
  int __error_code;
  __ssize_t __return_value;

#ifndef __USE_FILE_OFFSET64
  __off_t aio_offset;		/* File offset.  */
  char __pad[sizeof (__off64_t) - sizeof (__off_t)];
#else
  __off64_t aio_offset;		/* File offset.  */
#endif
  char __glibc_reserved[32];
};

/* The same for the 64bit offsets.  Please note that the members aio_fildes
   to __return_value have to be the same in aiocb and aiocb64.  */
#ifdef __USE_LARGEFILE64
struct aiocb64
{
  int aio_fildes;		/* File descriptor.  */
  int aio_lio_opcode;		/* Operation to be performed.  */
  int aio_reqprio;		/* Request priority offset.  */
  volatile void *aio_buf;	/* Location of buffer.  */
  size_t aio_nbytes;		/* Length of transfer.  */
  struct sigevent aio_sigevent;	/* Signal number and value.  */

  /* Internal members.  */
  struct aiocb *__next_prio;
  int __abs_prio;
  int __policy;
  int __error_code;
  __ssize_t __return_value;

  __off64_t aio_offset;		/* File offset.  */
  char __glibc_reserved[32];
};
#endif


#ifdef __USE_GNU
/* To optimize the implementation one can use the following struct.  */
struct aioinit
  {
    int aio_threads;		/* Maximum number of threads.  */
    int aio_num;		/* Number of expected simultaneous requests.  */
    int aio_locks;		/* Not used.  */
    int aio_usedba;		/* Not used.  */
    int aio_debug;		/* Not used.  */
    int aio_numusers;		/* Not used.  */
    int aio_idle_time;		/* Number of seconds before idle thread
				   terminates.  */
    int aio_reserved;
  };
#endif


/* Return values of the aio_cancel function.  */
enum
{
  AIO_CANCELED,
#define AIO_CANCELED AIO_CANCELED
  AIO_NOTCANCELED,
#define AIO_NOTCANCELED AIO_NOTCANCELED
  AIO_ALLDONE
#define AIO_ALLDONE AIO_ALLDONE
};


/* Operation codes for `aio_lio_opcode'.  */
enum
{
  LIO_READ,
#define LIO_READ LIO_READ
  LIO_WRITE,
#define LIO_WRITE LIO_WRITE
  LIO_NOP
#define LIO_NOP LIO_NOP
};


/* Synchronization options for `lio_listio' function.  */
enum
{
  LIO_WAIT,
#define LIO_WAIT LIO_WAIT
  LIO_NOWAIT
#define LIO_NOWAIT LIO_NOWAIT
};


/* Allow user to specify optimization.  */
#ifdef __USE_GNU
extern void aio_init (const struct aioinit *__init) __THROW __nonnull ((1));
#endif


#ifndef __USE_FILE_OFFSET64
/* Enqueue read request for given number of bytes and the given priority.  */
extern int aio_read (struct aiocb *__aiocbp) __THROW __nonnull ((1));
/* Enqueue write request for given number of bytes and the given priority.  */
extern int aio_write (struct aiocb *__aiocbp) __THROW __nonnull ((1));

/* Initiate list of I/O requests.  */
extern int lio_listio (int __mode,
		       struct aiocb *const __list[__restrict_arr],
		       int __nent, struct sigevent *__restrict __sig)
  __THROW __nonnull ((2));

/* Retrieve error status associated with AIOCBP.  */
extern int aio_error (const struct aiocb *__aiocbp) __THROW __nonnull ((1));
/* Return status associated with AIOCBP.  */
extern __ssize_t aio_return (struct aiocb *__aiocbp) __THROW __nonnull ((1));

/* Try to cancel asynchronous I/O requests outstanding against file
   descriptor FILDES.  */
extern int aio_cancel (int __fildes, struct aiocb *__aiocbp) __THROW;

/* Suspend calling thread until at least one of the asynchronous I/O
   operations referenced by LIST has completed.

   This function is a cancellation point and therefore not marked with
   __THROW.  */
extern int aio_suspend (const struct aiocb *const __list[], int __nent,
			const struct timespec *__restrict __timeout)
  __nonnull ((1));

/* Force all operations associated with file desriptor described by
   `aio_fildes' member of AIOCBP.  */
extern int aio_fsync (int __operation, struct aiocb *__aiocbp)
  __THROW __nonnull ((2));
#else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (aio_read, (struct aiocb *__aiocbp), aio_read64)
  __nonnull ((1));
extern int __REDIRECT_NTH (aio_write, (struct aiocb *__aiocbp), aio_write64)
  __nonnull ((1));

extern int __REDIRECT_NTH (lio_listio,
			   (int __mode,
			    struct aiocb *const __list[__restrict_arr],
			    int __nent, struct sigevent *__restrict __sig),
			   lio_listio64) __nonnull ((2));

extern int __REDIRECT_NTH (aio_error, (const struct aiocb *__aiocbp),
			   aio_error64) __nonnull ((1));
extern __ssize_t __REDIRECT_NTH (aio_return, (struct aiocb *__aiocbp),
				 aio_return64) __nonnull ((1));

extern int __REDIRECT_NTH (aio_cancel,
			   (int __fildes, struct aiocb *__aiocbp),
			   aio_cancel64);

extern int __REDIRECT_NTH (aio_suspend,
			   (const struct aiocb *const __list[], int __nent,
			    const struct timespec *__restrict __timeout),
			   aio_suspend64) __nonnull ((1));

extern int __REDIRECT_NTH (aio_fsync,
			   (int __operation, struct aiocb *__aiocbp),
			   aio_fsync64) __nonnull ((2));

# else
#  define aio_read aio_read64
#  define aio_write aio_write64
#  define lio_listio lio_listio64
#  define aio_error aio_error64
#  define aio_return aio_return64
#  define aio_cancel aio_cancel64
#  define aio_suspend aio_suspend64
#  define aio_fsync aio_fsync64
# endif
#endif

#ifdef __USE_LARGEFILE64
extern int aio_read64 (struct aiocb64 *__aiocbp) __THROW __nonnull ((1));
extern int aio_write64 (struct aiocb64 *__aiocbp) __THROW __nonnull ((1));

extern int lio_listio64 (int __mode,
			 struct aiocb64 *const __list[__restrict_arr],
			 int __nent, struct sigevent *__restrict __sig)
  __THROW __nonnull ((2));

extern int aio_error64 (const struct aiocb64 *__aiocbp)
  __THROW __nonnull ((1));
extern __ssize_t aio_return64 (struct aiocb64 *__aiocbp)
  __THROW __nonnull ((1));

extern int aio_cancel64 (int __fildes, struct aiocb64 *__aiocbp) __THROW;

extern int aio_suspend64 (const struct aiocb64 *const __list[], int __nent,
			  const struct timespec *__restrict __timeout)
  __THROW __nonnull ((1));

extern int aio_fsync64 (int __operation, struct aiocb64 *__aiocbp)
  __THROW __nonnull ((2));
#endif

__END_DECLS

#endif /* aio.h */