diff options
Diffstat (limited to 'lib/libc/sys/getsockopt.2')
| -rw-r--r-- | lib/libc/sys/getsockopt.2 | 58 |
1 files changed, 56 insertions, 2 deletions
diff --git a/lib/libc/sys/getsockopt.2 b/lib/libc/sys/getsockopt.2 index eed82c051dc..14ca672cb59 100644 --- a/lib/libc/sys/getsockopt.2 +++ b/lib/libc/sys/getsockopt.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: getsockopt.2,v 1.27 2010/07/01 13:39:19 jmc Exp $ +.\" $OpenBSD: getsockopt.2,v 1.28 2011/01/31 13:27:05 bluhm Exp $ .\" $NetBSD: getsockopt.2,v 1.7 1995/02/27 12:33:29 cgd Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 @@ -30,7 +30,7 @@ .\" .\" @(#)getsockopt.2 8.3 (Berkeley) 4/19/94 .\" -.Dd $Mdocdate: July 1 2010 $ +.Dd $Mdocdate: January 31 2011 $ .Dt GETSOCKOPT 2 .Os .Sh NAME @@ -150,6 +150,7 @@ and set with .It Dv SO_RCVTIMEO Ta "set timeout value for input" .It Dv SO_TIMESTAMP Ta "enables reception of a timestamp with datagrams" .It Dv SO_PEERCRED Ta "get the credentials from other side of connection" +.It Dv SO_SPLICE Ta "splice two sockets together or get data length" .It Dv SO_TYPE Ta "get the type of the socket (get only)" .It Dv SO_ERROR Ta "get and clear error on the socket (get only)" .El @@ -336,6 +337,59 @@ or .Xr connect 2 were called. .Pp +.Dv SO_SPLICE +can splice together two connected TCP sockets for zero-copy data +transfers. +In the first form, +.Fn setsockopt +is called with the source socket +.Fa s +and the drain socket's +.Vt int +file descriptor as +.Fa optval . +In the second form, +.Fa optval +is a +.Vt struct splice +with the drain socket in +.Va sp_fd +and a positive maximum number of bytes or 0 in +.Va sp_max . +If \-1 is given as drain socket, the source socket +.Fa s +gets unspliced. +Otherwise the spliced data transfer continues within the kernel +until the optional maximum is reached, one of the connections +terminates or an error occurs. +A successful +.Xr select 2 +or +.Xr poll 2 +operation testing the ability to read from the source socket, +indicates that the splicing has terminated. +In this case, the error status can be examined with +.Dv SO_ERROR +at the source socket. +Note that if a maximum is given, it is only guaranteed that no more +bytes are transferred. +A short splice can happen but then a second call to splice will +transfer the remaining data immediately. +Also the readability check will not indicate that the maximum has +been reached but that data after the maximum is available. +The +.Dv SO_SPLICE +option with +.Fn getsockopt +and an +.Vt off_t +value as +.Fa optval +can be used to retrieve the number of bytes transferred so far from the +source socket +.Fa s . +A successful new splice resets this number. +.Pp Finally, .Dv SO_TYPE and |