mexchange(9f) [sunos man page]

mexchange(9F)						   Kernel Functions for Drivers 					     mexchange(9F)

NAME

       mexchange - 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 reference (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 allocated. 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 ALSO

       dupmsg(9F), merror(9F)

       STREAMS Programming Guide

SunOS 5.10							    9 June 2004 						     mexchange(9F)

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merror(9F)						   Kernel Functions for Drivers 						merror(9F)

NAME

       merror - Send an M_ERROR message upstream

SYNOPSIS

       #include <sys/stream.h>
       #include <sys/strsun.h>

       void merror(queue_t *wq, mblk_t *mp, int error);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

PARAMETERS

       wq	Write queue associated with the read queue to send the M_ERROR on.

       mp	Optionally, a STREAMS message to convert to an M_ERROR.

       error	Error code to include in the M_ERROR message.

DESCRIPTION

       The merror() function constructs an M_ERROR message, and sends the resulting message upstream.

       If  mp  is NULL, merror() allocates a one-byte M_ERROR message. If mp is non-NULL, merror() attempts to convert the passed-in message to an
       M_ERROR. However, if the passed-in message has more than one reference (see dupmsg(9F)), or if it is of zero length, it is freed and a  new
       message is allocated.

       If  the	allocation  or	conversion  fails, merror() silently fails. Otherwise, the resulting one-byte data block is assigned the specified
       error code and sent upstream.

RETURN VALUES

       None.

CONTEXT

       This function can be called from user, kernel or interrupt context.

NOTES

       Callers must not hold any locks across an merror() that can be acquired as part of put(9E) processing.

SEE ALSO

       put(9E), dupmsg(9F)

       STREAMS Programming Guide

SunOS 5.11							    9 June 2004 							merror(9F)

Linux and UNIX Man Pages

mexchange(9f) [sunos man page]

Check Out this Related Man Page