aio_read(3p) — Linux manual page

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.1‐2017, aio.h(0p)

COPYRIGHT         top

       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 .

IEEE/The Open Group               2017                      AIO_READ(3P)

Pages that refer to this page: aio.h(0p)aio_cancel(3p)aio_error(3p)aio_return(3p)aio_suspend(3p)aio_write(3p)lio_listio(3p)