From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 21 Feb 2012 23:24:55 +0000 (+0000)
Subject: af_unix: MSG_TRUNC support for dgram sockets
X-Git-Tag: v3.4-rc1~177^2~226
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9f6f9af7694ede6314bed281eec74d588ba9474f;p=pandora-kernel.git

af_unix: MSG_TRUNC support for dgram sockets

Piergiorgio Beruto expressed the need to fetch size of first datagram in
queue for AF_UNIX sockets and suggested a patch against SIOCINQ ioctl.

I suggested instead to implement MSG_TRUNC support as a recv() input
flag, as already done for RAW, UDP & NETLINK sockets.

len = recv(fd, &byte, 1, MSG_PEEK | MSG_TRUNC);

MSG_TRUNC asks recv() to return the real length of the packet, even when
is was longer than the passed buffer.

There is risk that a userland application used MSG_TRUNC by accident
(since it had no effect on af_unix sockets) and this might break after
this patch.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

Reading git-diff-tree failed