dupb(D3) dupb(D3)
NAME
dupb - duplicate a message block
SYNOPSIS
#include <sys/stream.h>
#include <sys/ddi.h>
mblk_t *dupb(mblk_t *bp);
Arguments
bp Pointer to the message block to be duplicated.
DESCRIPTION
dupb creates a new message block structure that references the
same data block that is referenced by bp. Unlike copyb(D3),
dupb does not copy the information in the data block, but
creates a new structure to point to it.
Return Values
On success, dupb returns a pointer to the new message block.
On failure, it returns a NULL pointer.
USAGE
The following figure shows how the db_ref field of the data
block structure has been changed from 1 to 2, reflecting the
increase in the number of references to the data block. The
new message block contains the same information as the first.
Note that b_rptr and b_wptr are copied from bp, and that
db_ref is incremented.
Level
Base or Interrupt.
Synchronization Constraints
Does not sleep.
Driver-defined basic locks, read/write locks, and sleep locks
may be held across calls to this function.
REFERENCES
copyb(D3), dupmsg(D3), datab(D4), msgb(D4)
NOTICES
Portability
All processors
Copyright 1994 Novell, Inc. Page 1
dupb(D3) dupb(D3)
Applicability
ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp
Copyright 1994 Novell, Inc. Page 2