Disconnects the two specified streams.
The I_PUNLINK operation is used for disconnecting Multiplexed STREAMS configurations connected by a permanent link.
The I_PUNLINK operation disconnects the two streams specified by the fildes parameter and the arg parameter that are connected with a permanent link. The fildes parameter is the file descriptor of the stream connected to the multiplexing driver. The arg parameter is the multiplexer ID number that was returned by the I_PLINK operation. If the value of the arg parameter is MUXID_ALL, then all streams which are permanently linked to the stream specified by the fildes parameter are disconnected. As in the I_PLINK operation, this operation requires the multiplexing driver to acknowledge the unlink.
If unsuccessful, the errno global variable is set to one of the following values:
An I_PUNLINK operation can also be unsuccessful while waiting for the multiplexing driver to acknowledge the link request, if a message indicating an error or a hangup is received at the stream head of the fildes parameter. In addition, an error code can be returned in the positive or negative acknowledgment message. For these cases, the I_PUNLINK operation is unsuccessful and the errno global variable is set to the value in the message.
This operation is part of STREAMS Kernel Extensions.
The streamio operations.
The I_PLINK streamio operation, I_UNLINK streamio operation.