Date: Sat, 3 Jul 2010 12:14:01 +0000 (UTC) From: Christian Brueffer <brueffer@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r209661 - stable/8/lib/libc/sys Message-ID: <201007031214.o63CE13Z008626@svn.freebsd.org>
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Author: brueffer Date: Sat Jul 3 12:14:01 2010 New Revision: 209661 URL: http://svn.freebsd.org/changeset/base/209661 Log: MFC: r207923 Document FIONREAD, FIONWRITE and FIONSPACE. Modified: stable/8/lib/libc/sys/ioctl.2 Directory Properties: stable/8/lib/libc/sys/ (props changed) Modified: stable/8/lib/libc/sys/ioctl.2 ============================================================================== --- stable/8/lib/libc/sys/ioctl.2 Sat Jul 3 12:09:45 2010 (r209660) +++ stable/8/lib/libc/sys/ioctl.2 Sat Jul 3 12:14:01 2010 (r209661) @@ -29,7 +29,7 @@ .\" .\" $FreeBSD$ .\" -.Dd July 14, 2007 +.Dd May 11, 2010 .Dt IOCTL 2 .Os .Sh NAME @@ -80,6 +80,30 @@ Macros and defines used in specifying an .Fa request are located in the file .In sys/ioctl.h . +.Sh GENERIC IOCTLS +Some generic ioctls are not implemented for all types of file +descriptors. +These include: +.Bl -tag -width "xxxxxx" +.It Dv FIONREAD int +Get the number of bytes that are immediately available for reading. +.It Dv FIONWRITE int +Get the number of bytes in the descriptor's send queue. +These bytes are data which has been written to the descriptor but +which are being held by the kernel for further processing. +The nature of the required processing depends on the underlying device. +For TCP sockets, these bytes have not yet been acknowledged by the +other side of the connection. +.It Dv FIONSPACE int +Get the free space in the descriptor's send queue. +This value is the size of the send queue minus the number of bytes +being held in the queue. +Note: while this value represents the number of bytes that may be +added to the queue, other resource limitations may cause a write +not larger than the send queue's space to be blocked. +One such limitation would be a lack of network buffers for a write +to a network connection. +.El .Sh RETURN VALUES If an error has occurred, a value of -1 is returned and .Va errno
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