PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

AIO_READ(3P)              POSIX Programmer's Manual             AIO_READ(3P)

PROLOG         top

       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         top

       aio_read — asynchronous read from a file

SYNOPSIS         top

       #include <aio.h>

       int aio_read(struct aiocb *aiocbp);

DESCRIPTION         top

       The aio_read() function shall 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 to the file or device (even when the
       data cannot be delivered immediately).

       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 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.

       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_read().

       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.

       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         top

       The aio_read() 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         top

       The aio_read() 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_read(), or asynchronously. If any of the
       conditions below are detected synchronously, the aio_read() 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 is 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 reading.

       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_read() successfully queues the I/O operation
       but the operation is subsequently canceled or encounters an error,
       the return status of the asynchronous operation is one of the values
       normally returned by the read() function call. In addition, the error
       status of the asynchronous operation is set to one of the error
       statuses normally set by the read() function call, or one of the
       following values:

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

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

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

       The following condition may be detected synchronously or
       asynchronously:

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

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       aio_cancel(3p), aio_error(3p), lio_listio(3p), aio_return(3p),
       aio_write(3p), close(3p), exec(1p), exit(3p), fork(3p), lseek(3p),
       read(3p)

       The Base Definitions volume of POSIX.1‐2008, aio.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/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 .

IEEE/The Open Group                 2013                        AIO_READ(3P)