mirror of
https://github.com/freebsd/freebsd-src
synced 2024-10-06 16:40:47 +00:00
Document aio_read2/aio_write2
Reviewed by: jhb Discussed with: asomers Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D43448
This commit is contained in:
parent
8dfc788b84
commit
a52cb4c480
|
@ -383,8 +383,10 @@ MAN+= \
|
|||
sleep.3 \
|
||||
usleep.3
|
||||
|
||||
MLINKS+=aio_read.2 aio_readv.2
|
||||
MLINKS+=aio_write.2 aio_writev.2
|
||||
MLINKS+=aio_read.2 aio_readv.2 \
|
||||
aio_read.2 aio_read2.2
|
||||
MLINKS+=aio_write.2 aio_writev.2 \
|
||||
aio_write.2 aio_write2.2
|
||||
MLINKS+=accept.2 accept4.2
|
||||
MLINKS+=access.2 eaccess.2 \
|
||||
access.2 faccessat.2
|
||||
|
|
|
@ -22,11 +22,12 @@
|
|||
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||||
.\" SUCH DAMAGE.
|
||||
.\"
|
||||
.Dd November 15, 2023
|
||||
.Dd February 1, 2024
|
||||
.Dt AIO_READ 2
|
||||
.Os
|
||||
.Sh NAME
|
||||
.Nm aio_read ,
|
||||
.Nm aio_read2 ,
|
||||
.Nm aio_readv
|
||||
.Nd asynchronous read from a file (REALTIME)
|
||||
.Sh LIBRARY
|
||||
|
@ -35,21 +36,34 @@
|
|||
.In aio.h
|
||||
.Ft int
|
||||
.Fn aio_read "struct aiocb *iocb"
|
||||
.Ft int
|
||||
.Fn aio_read2 "struct aiocb *iocb" "int flags"
|
||||
.In sys/uio.h
|
||||
.Ft int
|
||||
.Fn aio_readv "struct aiocb *iocb"
|
||||
.Sh DESCRIPTION
|
||||
The
|
||||
.Fn aio_read
|
||||
.Fn aio_read ,
|
||||
.Fn aio_read2
|
||||
and
|
||||
.Fn aio_readv
|
||||
system calls allow the calling process to read
|
||||
from the descriptor
|
||||
.Fa iocb->aio_fildes
|
||||
beginning at the offset
|
||||
.Fa iocb->aio_offset .
|
||||
.Fa iocb->aio_fildes .
|
||||
The syscalls return 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.
|
||||
.Pp
|
||||
For the
|
||||
.Fn aio_read
|
||||
will read
|
||||
and
|
||||
.Fn aio_readv
|
||||
calls, the read begins at the offset
|
||||
.Fa iocb->aio_offset .
|
||||
.Pp
|
||||
The
|
||||
.Fn aio_read
|
||||
call will read
|
||||
.Fa iocb->aio_nbytes
|
||||
into the buffer pointed to by
|
||||
.Fa iocb->aio_buf ,
|
||||
|
@ -60,10 +74,6 @@ reads the data into the
|
|||
buffers specified by the members of the
|
||||
.Fa iocb->aio_iov
|
||||
array.
|
||||
Both syscalls return 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.
|
||||
.Pp
|
||||
For
|
||||
.Fn aio_readv
|
||||
the
|
||||
|
@ -72,6 +82,33 @@ structure is defined in
|
|||
.Xr readv 2 .
|
||||
.Pp
|
||||
The
|
||||
.Fn aio_read2
|
||||
call takes the
|
||||
.Fa flags
|
||||
argument.
|
||||
If
|
||||
.Fa flags
|
||||
is passed as zero, the call behaves identically to
|
||||
.Fn aio_read .
|
||||
The following flags can be specified by logical or:
|
||||
.Bl -tag -width AIO_OP2_VECTORED
|
||||
.It AIO_OP2_FOFFSET
|
||||
The read occurs at the file descriptor offset,
|
||||
which is advanced by the operation as done by the
|
||||
.Xr read 2
|
||||
syscall.
|
||||
The
|
||||
.Fa iocb->aio_offset
|
||||
field is ignored.
|
||||
.It AIO_OP2_VECTORED
|
||||
Similar to
|
||||
.Fn aio_readv ,
|
||||
the read buffers are specified by the
|
||||
.Fa aiocb->aio_iov
|
||||
array.
|
||||
.El
|
||||
.Pp
|
||||
The
|
||||
.Fa iocb
|
||||
pointer may be subsequently used as an argument to
|
||||
.Fn aio_return
|
||||
|
@ -103,9 +140,8 @@ operation has completed.
|
|||
.Pp
|
||||
The asynchronous I/O control buffer
|
||||
.Fa iocb
|
||||
should be zeroed before the
|
||||
.Fn aio_read
|
||||
call to avoid passing bogus context information to the kernel.
|
||||
should be zeroed before the system
|
||||
calls to avoid passing bogus context information to the kernel.
|
||||
.Pp
|
||||
Modifications of the Asynchronous I/O Control Block structure or the
|
||||
buffer contents are not allowed while the request is queued.
|
||||
|
@ -116,12 +152,13 @@ is past the offset maximum for
|
|||
.Fa iocb->aio_fildes ,
|
||||
no I/O will occur.
|
||||
.Sh RETURN VALUES
|
||||
.Rv -std aio_read aio_readv
|
||||
.Rv -std aio_read aio_read2 aio_readv
|
||||
.Sh DIAGNOSTICS
|
||||
None.
|
||||
.Sh ERRORS
|
||||
The
|
||||
.Fn aio_read
|
||||
.Fn aio_read ,
|
||||
.Fn aio_read2 ,
|
||||
and
|
||||
.Fn aio_readv
|
||||
system calls will fail if:
|
||||
|
@ -149,10 +186,7 @@ or
|
|||
system call is made, or asynchronously, at any time thereafter.
|
||||
If they
|
||||
are detected at call time,
|
||||
.Fn aio_read
|
||||
or
|
||||
.Fn aio_readv
|
||||
returns -1 and sets
|
||||
The calls return -1 and set
|
||||
.Va errno
|
||||
appropriately; otherwise the
|
||||
.Fn aio_return
|
||||
|
@ -226,8 +260,11 @@ system call is expected to conform to the
|
|||
.St -p1003.1
|
||||
standard.
|
||||
The
|
||||
.Fn aio_read2
|
||||
and
|
||||
.Fn aio_readv
|
||||
system call is a FreeBSD extension, and should not be used in portable code.
|
||||
system calls are FreeBSD extensions,
|
||||
and should not be used in portable code.
|
||||
.Sh HISTORY
|
||||
The
|
||||
.Fn aio_read
|
||||
|
@ -237,6 +274,10 @@ The
|
|||
.Fn aio_readv
|
||||
system call first appeared in
|
||||
.Fx 13.0 .
|
||||
The
|
||||
.Fn aio_read2
|
||||
system call first appeared in
|
||||
.Fx 14.1 .
|
||||
.Sh AUTHORS
|
||||
This
|
||||
manual page was written by
|
||||
|
|
|
@ -22,11 +22,12 @@
|
|||
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||||
.\" SUCH DAMAGE.
|
||||
.\"
|
||||
.Dd November 15, 2023
|
||||
.Dd February 1, 2024
|
||||
.Dt AIO_WRITE 2
|
||||
.Os
|
||||
.Sh NAME
|
||||
.Nm aio_write ,
|
||||
.Nm aio_write2 ,
|
||||
.Nm aio_writev
|
||||
.Nd asynchronous write to a file (REALTIME)
|
||||
.Sh LIBRARY
|
||||
|
@ -35,19 +36,27 @@
|
|||
.In aio.h
|
||||
.Ft int
|
||||
.Fn aio_write "struct aiocb *iocb"
|
||||
.Ft int
|
||||
.Fn aio_write2 "struct aiocb *iocb" "int flags"
|
||||
.In sys/uio.h
|
||||
.Ft int
|
||||
.Fn aio_writev "struct aiocb *iocb"
|
||||
.Sh DESCRIPTION
|
||||
The
|
||||
.Fn aio_write
|
||||
.Fn aio_write ,
|
||||
.Fn aio_write2 ,
|
||||
and
|
||||
.Fn aio_writev
|
||||
system calls allow the calling process to write
|
||||
to the descriptor
|
||||
.Fa iocb->aio_fildes .
|
||||
The syscalls return immediately after the write request has been enqueued
|
||||
to the descriptor; the write may or may not have completed at the time
|
||||
the call returns.
|
||||
.Pp
|
||||
The
|
||||
.Fn aio_write
|
||||
will write
|
||||
call will write
|
||||
.Fa iocb->aio_nbytes
|
||||
from the buffer pointed to by
|
||||
.Fa iocb->aio_buf ,
|
||||
|
@ -58,9 +67,7 @@ gathers the data from the
|
|||
buffers specified by the members of the
|
||||
.Fa iocb->aio_iov
|
||||
array.
|
||||
Both syscalls return immediately after the write request has been enqueued
|
||||
to the descriptor; the write may or may not have completed at the time
|
||||
the call returns.
|
||||
.Pp
|
||||
If the request could not be enqueued, generally due
|
||||
to invalid arguments, the call returns without having enqueued the
|
||||
request.
|
||||
|
@ -80,11 +87,42 @@ write operations append to the file in the same order as the calls were
|
|||
made.
|
||||
If
|
||||
.Dv O_APPEND
|
||||
is not set for the file descriptor, the write operation will occur at
|
||||
is not set for the file descriptor, the write operation for
|
||||
.Fn aio_write
|
||||
will occur at
|
||||
the absolute position from the beginning of the file plus
|
||||
.Fa iocb->aio_offset .
|
||||
.Pp
|
||||
The
|
||||
.Fn aio_write2
|
||||
call takes the
|
||||
.Fa flags
|
||||
argument.
|
||||
If
|
||||
.Fa flags
|
||||
is passed as zero, the call behaves identically to
|
||||
.Fn aio_write .
|
||||
The following flags can be specified by logical or:
|
||||
.Bl -tag -width AIO_OP2_VECTORED
|
||||
.It AIO_OP2_FOFFSET
|
||||
The write for non
|
||||
.Dv O_APPEND
|
||||
file descriptors occurs at the file descriptor offset,
|
||||
which is advanced by the operation as done by the
|
||||
.Xr write 2
|
||||
syscall.
|
||||
The
|
||||
.Fa iocb->aio_offset
|
||||
field is ignored.
|
||||
.It AIO_OP2_VECTORED
|
||||
Similar to
|
||||
.Fn aio_writev ,
|
||||
the write buffers are specified by the
|
||||
.Fa aiocb->aio_iov
|
||||
array.
|
||||
.El
|
||||
.Pp
|
||||
The
|
||||
.Fa iocb
|
||||
pointer may be subsequently used as an argument to
|
||||
.Fn aio_return
|
||||
|
@ -114,10 +152,7 @@ operation has completed.
|
|||
The asynchronous I/O control buffer
|
||||
.Fa iocb
|
||||
should be zeroed before the
|
||||
.Fn aio_write
|
||||
or
|
||||
.Fn aio_writev
|
||||
system call to avoid passing bogus context information to the kernel.
|
||||
system calls to avoid passing bogus context information to the kernel.
|
||||
.Pp
|
||||
Modifications of the Asynchronous I/O Control Block structure or the
|
||||
buffer contents are not allowed while the request is queued.
|
||||
|
@ -131,7 +166,8 @@ no I/O will occur.
|
|||
.Rv -std aio_write aio_writev
|
||||
.Sh ERRORS
|
||||
The
|
||||
.Fn aio_write
|
||||
.Fn aio_write ,
|
||||
.Fn aio_write2 ,
|
||||
and
|
||||
.Fn aio_writev
|
||||
system calls will fail if:
|
||||
|
@ -153,16 +189,13 @@ are unsafe and unsafe asynchronous I/O operations are disabled.
|
|||
.El
|
||||
.Pp
|
||||
The following conditions may be synchronously detected when the
|
||||
.Fn aio_write
|
||||
.Fn aio_write ,
|
||||
.Fn aio_write2 ,
|
||||
or
|
||||
.Fn aio_writev
|
||||
system call is made, or asynchronously, at any time thereafter.
|
||||
If they
|
||||
are detected at call time,
|
||||
.Fn aio_write
|
||||
or
|
||||
.Fn aio_writev
|
||||
returns -1 and sets
|
||||
are detected at call time, the calls return -1 and set
|
||||
.Va errno
|
||||
appropriately; otherwise the
|
||||
.Fn aio_return
|
||||
|
@ -229,8 +262,11 @@ is expected to conform to the
|
|||
standard.
|
||||
.Pp
|
||||
The
|
||||
.Fn aio_write2
|
||||
and
|
||||
.Fn aio_writev
|
||||
system call is a FreeBSD extension, and should not be used in portable code.
|
||||
system calls are FreeBSD extensions,
|
||||
and should not be used in portable code.
|
||||
.Sh HISTORY
|
||||
The
|
||||
.Fn aio_write
|
||||
|
@ -240,6 +276,10 @@ The
|
|||
.Fn aio_writev
|
||||
system call first appeared in
|
||||
.Fx 13.0 .
|
||||
The
|
||||
.Fn aio_write2
|
||||
system call first appeared in
|
||||
.Fx 14.1 .
|
||||
.Sh AUTHORS
|
||||
This manual page was written by
|
||||
.An Wes Peters Aq Mt wes@softweyr.com .
|
||||
|
|
Loading…
Reference in a new issue