PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       aio_write — asynchronous write to a file

SYNOPSIS

       #include <aio.h>

       int aio_write(struct aiocb *aiocbp);

DESCRIPTION

       The  aio_write()  function  shall  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 to the file or
       device.

       If prioritized I/O is supported for this file, then the asynchronous  operation  shall  be
       submitted  at a priority equal to a base scheduling priority minus aiocbp->aio_reqprio. If
       Thread Execution Scheduling is not supported, then the base scheduling priority is that of
       the calling process;
       otherwise, the base scheduling priority is that of the calling thread.

       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.

       The  aiocbp  argument  points  to  an  aiocb  structure.  If  the  buffer  pointed  to  by
       aiocbp->aio_buf or the control block pointed to by aiocbp becomes an illegal address prior
       to asynchronous I/O completion, then the behavior is undefined.

       If  O_APPEND  is  not set for the file descriptor aio_fildes, then the requested operation
       shall take 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.  If O_APPEND  is  set  for  the  file  descriptor,  or  if
       aio_fildes  is  associated  with  a  device that is incapable of seeking, write operations
       append to the file in the same order as the calls were made,  except  under  circumstances
       described  in  Section  2.8.2,  Asynchronous  I/O.   After a successful call to enqueue an
       asynchronous I/O operation, the value of the file offset for the file is unspecified.

       The aio_sigevent member specifies the  notification  which  occurs  when  the  request  is
       completed.

       The aiocbp->aio_lio_opcode field shall be ignored by aio_write().

       Simultaneous asynchronous operations using the same aiocbp produce undefined results.

       If  synchronized  I/O  is  enabled  on  the  file  associated with aiocbp->aio_fildes, the
       behavior of this function shall be according to the definitions of synchronized  I/O  data
       integrity completion, and synchronized I/O file integrity completion.

       For  any  system action that changes the process memory space while an asynchronous I/O is
       outstanding to the address range being changed, the result of that action is undefined.

       For regular files, no data transfer shall occur past the offset maximum established in the
       open file description associated with aiocbp->aio_fildes.

RETURN VALUE

       The  aio_write() function shall return the value zero if the I/O operation is successfully
       queued; otherwise, the function shall return the value -1 and set errno  to  indicate  the
       error.

ERRORS

       The aio_write() function shall fail if:

       EAGAIN The  requested  asynchronous  I/O  operation  was not queued due to system resource
              limitations.

       Each of the following conditions may be detected synchronously at the time of the call  to
       aio_write(), or asynchronously. If any of the conditions below are detected synchronously,
       the aio_write() function shall return -1 and set errno to the corresponding value. If  any
       of the conditions below are detected asynchronously, the return status of the asynchronous
       operation shall be set to -1, and the error status of the asynchronous operation is set to
       the corresponding value.

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid,
              aiocbp->aio_reqprio  is  not  a  valid  value,  or aiocbp->aio_nbytes is an invalid
              value.

       In the case that the aio_write() successfully queues the I/O operation, the return  status
       of  the asynchronous operation shall be one of the values normally returned by the write()
       function call. If the operation is successfully queued but  is  subsequently  canceled  or
       encounters  an  error, the error status for the asynchronous operation contains one of the
       values normally set by the write() function call, or one of the following:

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid.

       ECANCELED
              The requested I/O was  canceled  before  the  I/O  completed  due  to  an  explicit
              aio_cancel() request.

       The following condition may be detected synchronously or asynchronously:

       EFBIG  The  file is a regular file, aiobcp->aio_nbytes is greater than 0, and the starting
              offset in aiobcp->aio_offset is at or beyond the offset maximum in  the  open  file
              description associated with aiocbp->aio_fildes.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section  2.8.2,  Asynchronous  I/O,  aio_cancel(),  aio_error(), aio_read(), aio_return(),
       close(), exec, exit(), fork(), lio_listio(), lseek(), write()

       The Base Definitions volume of POSIX.1‐2017, <aio.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1-2017,  Standard  for  Information Technology -- Portable Operating System Interface
       (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C)  2018  by
       the  Institute  of  Electrical  and Electronics Engineers, Inc and The Open Group.  In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .