diff options
Diffstat (limited to 'lib/libc/sys/aio_read.2')
| -rw-r--r-- | lib/libc/sys/aio_read.2 | 63 |
1 files changed, 52 insertions, 11 deletions
diff --git a/lib/libc/sys/aio_read.2 b/lib/libc/sys/aio_read.2 index bbf96cc89890..0327ef1f747b 100644 --- a/lib/libc/sys/aio_read.2 +++ b/lib/libc/sys/aio_read.2 @@ -24,11 +24,12 @@ .\" .\" $FreeBSD$ .\" -.Dd August 19, 2016 +.Dd January 2, 2021 .Dt AIO_READ 2 .Os .Sh NAME -.Nm aio_read +.Nm aio_read , +.Nm aio_readv .Nd asynchronous read from a file (REALTIME) .Sh LIBRARY .Lb libc @@ -36,21 +37,42 @@ .In aio.h .Ft int .Fn aio_read "struct aiocb *iocb" +.In sys/uio.h +.Ft int +.Fn aio_readv "struct aiocb *iocb" .Sh DESCRIPTION The .Fn aio_read -system call allows the calling process to read -.Fa iocb->aio_nbytes +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 -into the buffer pointed to by -.Fa iocb->aio_buf . -The call returns immediately after the read request has +.Fa iocb->aio_offset . +.Fn aio_read +will read +.Fa iocb->aio_nbytes +from the buffer pointed to by +.Fa iocb->aio_buf , +whereas +.Fn aio_readv +reads the data into the +.Fa iocb->aio_iovcnt +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 +.Fa iovec +structure is defined in +.Xr readv 2 . +.Pp 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 @@ -61,7 +83,9 @@ The argument is ignored by the .Fn aio_read -system call. +and +.Fn aio_readv +system calls. .Pp The .Fa iocb @@ -108,16 +132,22 @@ is past the offset maximum for .Fa iocb->aio_fildes , no I/O will occur. .Sh RETURN VALUES -.Rv -std aio_read +.Rv -std aio_read aio_readv .Sh DIAGNOSTICS None. .Sh ERRORS The .Fn aio_read -system call will fail if: +and +.Fn aio_readv +system calls will fail if: .Bl -tag -width Er .It Bq Er EAGAIN The request was not queued because of system resource limitations. +.It Bq Er EFAULT +Part of +.Fa aio_iov +points outside the process's allocated address space. .It Bq Er EINVAL The asynchronous notification method in .Fa iocb->aio_sigevent.sigev_notify @@ -130,10 +160,14 @@ are unsafe and unsafe asynchronous I/O operations are disabled. .Pp The following conditions may be synchronously detected when the .Fn aio_read +or +.Fn aio_readv 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 .Va errno appropriately; otherwise the @@ -207,11 +241,18 @@ The system call is expected to conform to the .St -p1003.1 standard. +The +.Fn aio_readv +system call is a FreeBSD extension, and should not be used in portable code. .Sh HISTORY The .Fn aio_read system call first appeared in .Fx 3.0 . +The +.Fn aio_readv +system call first appeared in +.Fx 13.0 . .Sh AUTHORS This manual page was written by |