sctp: implement SIOCINQ ioctl() (take 3)

This simple patch copies the current approach for SIOCINQ ioctl() from DCCP
into SCTP so that the userland code working with SCTP can use a similar
interface across different protocols to know how much space to allocate for
a buffer.

Signed-off-by: Diego Elio Pettenò <flameeyes@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Diego Elio 'Flameeyes' Pettenò 2010-09-03 03:47:03 +00:00 committed by David S. Miller
parent 2edae08e5b
commit 65040c33ee
1 changed files with 34 additions and 1 deletions

View File

@ -3592,7 +3592,40 @@ out:
/* The SCTP ioctl handler. */
SCTP_STATIC int sctp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
return -ENOIOCTLCMD;
int rc = -ENOTCONN;
sctp_lock_sock(sk);
/*
* SEQPACKET-style sockets in LISTENING state are valid, for
* SCTP, so only discard TCP-style sockets in LISTENING state.
*/
if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
goto out;
switch (cmd) {
case SIOCINQ: {
struct sk_buff *skb;
unsigned int amount = 0;
skb = skb_peek(&sk->sk_receive_queue);
if (skb != NULL) {
/*
* We will only return the amount of this packet since
* that is all that will be read.
*/
amount = skb->len;
}
rc = put_user(amount, (int __user *)arg);
}
break;
default:
rc = -ENOIOCTLCMD;
break;
}
out:
sctp_release_sock(sk);
return rc;
}
/* This is the function which gets called during socket creation to