mexchange(9f) [opensolaris 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 5.11							    9 June 2004 						     mexchange(9F)

Check Out this Related Man Page

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

NAME

       dupmsg - duplicate a message

SYNOPSIS

       #include <sys/stream.h>

       mblk_t *dupmsg(mblk_t *mp);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       mp     Pointer to the message.

DESCRIPTION

       dupmsg()  forms a new message by copying the message block descriptors pointed to by  mp and linking them. dupb(9F) is called for each mes-
       sage block. The data blocks themselves are not duplicated.

RETURN VALUES

       If successful,  dupmsg() returns a pointer to the new message block. Otherwise, it returns a  NULL pointer. A return value of   NULL  indi-
       cates either memory depletion or the data block reference count, db_ref (see datab(9S)), has reached a limit(255). See  dupb(9F).

CONTEXT

       dupmsg() can be called from user, kernel, or interrupt context.

EXAMPLES

       Example 1 Using dupmsg()

       See copyb(9F) for an example using dupmsg().

SEE ALSO

       copyb(9F), copymsg(9F), dupb(9F), datab(9S)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.11							    11 Apr 1991 							dupmsg(9F)

Linux and UNIX Man Pages

mexchange(9f) [opensolaris man page]

Check Out this Related Man Page