MEXCHANGE(9F)MEXCHANGE(9F)NAMEmexchange - Exchange one message for another
SYNOPSIS
#include <sys/stream.h>
#include <sys/strsun.h>
mblk_t *mexchange(queue_t *wq, mblk_t *mp, size_t size,
uchar_t type, int32_t primtype);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
PARAMETERS
wq
Optionally, write queue associated with the read queue to
be used on failure (see below).
mp
Optionally, the message to exchange.
size
Size of the returned message.
type
Type of the returned message.
primtype
Optionally, a 4 byte value to store at the beginning of the
returned message.
DESCRIPTION
The mexchange() function exchanges the passed in message for another
message of the specified size and type.
If mp is not NULL, is of at least size bytes, and has only one refer‐
ence (see dupmsg(9F)), mp is converted to be of the specified size and
type. Otherwise, a new message of the specified size and type is allo‐
cated. If allocation fails, and wq is not NULL, merror(9F) attempts to
send an error to the stream head.
Finally, if primtype is not -1 and size is at least 4 bytes, the first
4 bytes are assigned to be primtype. This is chiefly useful for
STREAMS-based protocols such as DLPI and TPI which store the protocol
message type in the first 4 bytes of each message.
RETURN VALUES
A pointer to the requested message is returned on success. NULL is
returned on failure.
CONTEXT
This function can be called from user, kernel or interrupt context.
SEE ALSOdupmsg(9F), merror(9F)
STREAMS Programming Guide
Jun 9, 2004 MEXCHANGE(9F)
