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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 <xemul@parallels.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Emelyanov 2012-02-21 07:32:06 +00:00 committed by David S. Miller
parent f55bb7f9cb
commit fc0d753641
1 changed files with 18 additions and 2 deletions
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20
net/unix/af_unix.c
View File

@ -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);