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aio_waitcomplete(2) [freebsd man page]

AIO_WAITCOMPLETE(2)					      BSD System Calls Manual					       AIO_WAITCOMPLETE(2)

NAME
aio_waitcomplete -- wait for the next completion of an aio request LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <aio.h> int aio_waitcomplete(struct aiocb **iocbp, struct timespec *timeout); DESCRIPTION
The aio_waitcomplete() system call waits for completion of an asynchronous I/O request. Upon completion, aio_waitcomplete() returns the result of the function and sets iocbp to point to the structure associated with the original request. If an asynchronous I/O request is com- pleted before aio_waitcomplete() is called, it returns immediately with the completed request. If timeout is a non-NULL pointer, it specifies a maximum interval to wait for a asynchronous I/O request to complete. If timeout is a NULL pointer, aio_waitcomplete() waits indefinitely. To effect a poll, the timeout argument should be non-NULL, pointing to a zero-valued timeval structure. The aio_waitcomplete() system call also serves the function of aio_return(), thus aio_return() should not be called for the control block returned in iocbp. RETURN VALUES
If an asynchronous I/O request has completed, iocbp is set to point to the control block passed with the original request, and the status is returned as described in read(2), write(2), or fsync(2). On failure, aio_waitcomplete() returns -1, sets iocbp to NULL and sets errno to indicate the error condition. ERRORS
The aio_waitcomplete() system call fails if: [EINVAL] The specified time limit is invalid. [EAGAIN] The process has not yet called aio_read() or aio_write(). [EINTR] A signal was delivered before the timeout expired and before any asynchronous I/O requests completed. [EWOULDBLOCK] [EINPROGRESS] The specified time limit expired before any asynchronous I/O requests completed. SEE ALSO
aio_cancel(2), aio_error(2), aio_read(2), aio_return(2), aio_suspend(2), aio_write(2), fsync(2), read(2), write(2), aio(4) STANDARDS
The aio_waitcomplete() system call is a FreeBSD-specific extension. HISTORY
The aio_waitcomplete() system call first appeared in FreeBSD 4.0. AUTHORS
The aio_waitcomplete() system call and this manual page were written by Christopher M Sedore <cmsedore@maxwell.syr.edu>. BSD
January 19, 2000 BSD

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AIO_READ(2)						      BSD System Calls Manual						       AIO_READ(2)

NAME
aio_read -- asynchronous read from a file (REALTIME) LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <aio.h> int aio_read(struct aiocb *iocb); DESCRIPTION
The aio_read() system call allows the calling process to read iocb->aio_nbytes from the descriptor iocb->aio_fildes beginning at the offset iocb->aio_offset into the buffer pointed to by iocb->aio_buf. The call returns immediately after the read request has been enqueued to the descriptor; the read may or may not have completed at the time the call returns. If _POSIX_PRIORITIZED_IO is defined, and the descriptor supports it, then the enqueued operation is submitted at a priority equal to that of the calling process minus iocb->aio_reqprio. The iocb->aio_lio_opcode argument is ignored by the aio_read() system call. The iocb pointer may be subsequently used as an argument to aio_return() and aio_error() in order to determine return or error status for the enqueued operation while it is in progress. If the request could not be enqueued (generally due to invalid arguments), then the call returns without having enqueued the request. If the request is successfully enqueued, the value of iocb->aio_offset can be modified during the request as context, so this value must not be referenced after the request is enqueued. RESTRICTIONS
The Asynchronous I/O Control Block structure pointed to by iocb and the buffer that the iocb->aio_buf member of that structure references must remain valid until the operation has completed. For this reason, use of auto (stack) variables for these objects is discouraged. The asynchronous I/O control buffer iocb should be zeroed before the aio_read() call to avoid passing bogus context information to the ker- nel. Modifications of the Asynchronous I/O Control Block structure or the buffer contents after the request has been enqueued, but before the request has completed, are not allowed. If the file offset in iocb->aio_offset is past the offset maximum for iocb->aio_fildes, no I/O will occur. RETURN VALUES
The aio_read() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indi- cate the error. DIAGNOSTICS
None. ERRORS
The aio_read() system call will fail if: [EAGAIN] The request was not queued because of system resource limitations. [ENOSYS] The aio_read() system call is not supported. The following conditions may be synchronously detected when the aio_read() system call is made, or asynchronously, at any time thereafter. If they are detected at call time, aio_read() returns -1 and sets errno appropriately; otherwise the aio_return() system call must be called, and will return -1, and aio_error() must be called to determine the actual value that would have been returned in errno. [EBADF] The iocb->aio_fildes argument is invalid. [EINVAL] The offset iocb->aio_offset is not valid, the priority specified by iocb->aio_reqprio is not a valid priority, or the num- ber of bytes specified by iocb->aio_nbytes is not valid. [EOVERFLOW] The file is a regular file, iocb->aio_nbytes is greater than zero, the starting offset in iocb->aio_offset is before the end of the file, but is at or beyond the iocb->aio_fildes offset maximum. If the request is successfully enqueued, but subsequently cancelled or an error occurs, the value returned by the aio_return() system call is per the read(2) system call, and the value returned by the aio_error() system call is either one of the error returns from the read(2) system call, or one of: [EBADF] The iocb->aio_fildes argument is invalid for reading. [ECANCELED] The request was explicitly cancelled via a call to aio_cancel(). [EINVAL] The offset iocb->aio_offset would be invalid. SEE ALSO
aio_cancel(2), aio_error(2), aio_return(2), aio_suspend(2), aio_waitcomplete(2), aio_write(2), siginfo(3), aio(4) STANDARDS
The aio_read() system call is expected to conform to the IEEE Std 1003.1 (``POSIX.1'') standard. HISTORY
The aio_read() system call first appeared in FreeBSD 3.0. AUTHORS
This manual page was written by Terry Lambert <terry@whistle.com>. BUGS
Invalid information in iocb->_aiocb_private may confuse the kernel. BSD
November 17, 1998 BSD

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