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AIO_WRITE(3) Linux Programmer's Manual AIO_WRITE(3)

NAME

     aio_write - asynchronous write

SYNOPSIS

     #include <aio.h>

     int aio_write(struct aiocb *aiocbp);

     Link with -lrt.

DESCRIPTION

     The aio_write() function queues the I/O request described by the buffer
     pointed to by aiocbp.  This function  is  the  asynchronous  analog  of
     write(2).  The arguments of the call

         write(fd, buf, count)

     correspond (in order) to the fields aio_fildes, aio_buf, and aio_nbytes
     of the structure pointed to by aiocbp.  (See aio(7) for  a  description
     of the aiocb structure.)

     If  O_APPEND  is  not set, the data is written starting at the absolute
     position  aiocbp->aio_offset,  regardless  of  the  file  offset.    If
     O_APPEND  is  set,  data  is written at the end of the file in the same
     order as aio_write() calls are made.  After the call, the value of  the
     file offset is unspecified.

     The  "asynchronous" means that this call returns as soon as the request
     has been enqueued; the write may or may not  have  completed  when  the
     call returns.  One tests for completion using aio_error(3).  The return
     status of a completed I/O  operation  can  be  obtained  aio_return(3).
     Asynchronous  notification of I/O completion can be obtained by setting
     aiocbp->aio_sigevent appropriately; see sigevent(7) for details.

     If _POSIX_PRIORITIZED_IO is defined, and this file  supports  it,  then
     the  asynchronous operation is submitted at a priority equal to that of
     the calling process minus aiocbp->aio_reqprio.

     The field aiocbp->aio_lio_opcode is ignored.

     No data is written to a regular file beyond its maximum offset.

RETURN VALUE

     On success, 0 is returned.  On error, the request is not  enqueued,  -1
     is  returned,  and errno is set appropriately.  If an error is detected
     only later, it will be reported via aio_return(3) (returns  status  -1)
     and  aio_error(3)  (error  status--whatever  one  would  have gotten in
     errno, such as EBADF).

ERRORS

     EAGAIN Out of resources.

     EBADF  aio_fildes is not a valid file descriptor open for writing.

     EFBIG  The file is a regular file, we want to write at least one  byte,
            but the starting position is at or beyond the maximum offset for
            this file.

     EINVAL One or more of aio_offset, aio_reqprio, aio_nbytes are  invalid.

     ENOSYS aio_write() is not implemented.

VERSIONS

     The aio_write() function is available since glibc 2.1.

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     +------------+---------------+---------+
     |Interface   | Attribute     | Value   |
     +------------+---------------+---------+
     |aio_write() | Thread safety | MT-Safe |
     +------------+---------------+---------+

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008.

NOTES

     It is a good idea to zero out the control block before use.   The  con-
     trol  block  must  not  be  changed  while  the  write  operation is in
     progress.  The buffer area being written out must not be accessed  dur-
     ing  the  operation  or  undefined results may occur.  The memory areas
     involved must remain valid.

     Simultaneous I/O operations specifying the same aiocb structure produce
     undefined results.