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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2012-02-21 23:24:55 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-02-22 14:47:02 -0500 |
| commit | 9f6f9af7694ede6314bed281eec74d588ba9474f (patch) | |
| tree | 4b1825f2432916f117f9104153b9c37cf58458ae /net/unix | |
| parent | cdf49c283e2e105da86ca575ad35b453f5ff24ea (diff) | |
| download | lwn-9f6f9af7694ede6314bed281eec74d588ba9474f.tar.gz lwn-9f6f9af7694ede6314bed281eec74d588ba9474f.zip | |
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>
Diffstat (limited to 'net/unix')
| -rw-r--r-- | net/unix/af_unix.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 0be4d24f6ae8..8ee85aa79fa7 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1845,7 +1845,7 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock, if (UNIXCB(skb).fp) siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp); } - err = size; + err = (flags & MSG_TRUNC) ? skb->len - skip : size; scm_recv(sock, msg, siocb->scm, flags); |