From fc0d753641f7b919c7273d9bd21ae6ab45e757f3 Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Tue, 21 Feb 2012 07:32:06 +0000 Subject: [PATCH] unix: Support peeking offset for stream sockets The same here -- we can protect the sk_peek_off manipulations with the unix_sk->readlock mutex. The peeking of data from a stream socket is done in the datagram style, i.e. even if there's enough room for more data in the user buffer, only the head skb's data is copied in there. This feature is preserved when peeking data from a given offset -- the data is read till the nearest skb's boundary. Signed-off-by: Pavel Emelyanov Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/unix/af_unix.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 3d9481de031f..0be4d24f6ae8 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -559,6 +559,7 @@ static const struct proto_ops unix_stream_ops = { .recvmsg = unix_stream_recvmsg, .mmap = sock_no_mmap, .sendpage = sock_no_sendpage, + .set_peek_off = unix_set_peek_off, }; static const struct proto_ops unix_dgram_ops = { @@ -1904,6 +1905,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, int target; int err = 0; long timeo; + int skip; err = -EINVAL; if (sk->sk_state != TCP_ESTABLISHED) @@ -1933,12 +1935,15 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, goto out; } + skip = sk_peek_offset(sk, flags); + do { int chunk; struct sk_buff *skb; unix_state_lock(sk); skb = skb_peek(&sk->sk_receive_queue); +again: if (skb == NULL) { unix_sk(sk)->recursion_level = 0; if (copied >= target) @@ -1973,6 +1978,13 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, unix_state_unlock(sk); break; } + + if (skip >= skb->len) { + skip -= skb->len; + skb = skb_peek_next(skb, &sk->sk_receive_queue); + goto again; + } + unix_state_unlock(sk); if (check_creds) { @@ -1992,8 +2004,8 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, sunaddr = NULL; } - chunk = min_t(unsigned int, skb->len, size); - if (memcpy_toiovec(msg->msg_iov, skb->data, chunk)) { + chunk = min_t(unsigned int, skb->len - skip, size); + if (memcpy_toiovec(msg->msg_iov, skb->data + skip, chunk)) { if (copied == 0) copied = -EFAULT; break; @@ -2005,6 +2017,8 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, if (!(flags & MSG_PEEK)) { skb_pull(skb, chunk); + sk_peek_offset_bwd(sk, chunk); + if (UNIXCB(skb).fp) unix_detach_fds(siocb->scm, skb); @@ -2022,6 +2036,8 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, if (UNIXCB(skb).fp) siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp); + sk_peek_offset_fwd(sk, chunk); + break; } } while (size); -- 2.20.1