MBLKHEAD

, MBLKIN

, MBLKL

, MBLKSIZE

, MBLKTAIL

- Message block utility macros

Synopsis

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

int MBLKHEAD(mblk_t *mp);

int MBLKTAIL(mblk_t *mp);

int MBLKSIZE(mblk_t *mp);

int MBLKL(mblk_t *mp);

int MBLKIN(mblk_t *mp, int offset, int len);

Interface Level

Solaris DDI specific (Solaris DDI).

Parameters

mp

Message to be examined.

offset

Offset from mp->b_rptr from which to start examining.

len

Number of bytes to examine.

Description

The MBLKHEAD() macro calculates the number of bytes between the first byte and the first unread byte of the message block, that is: mp->b_rptr - mp->b_datap->db_base.

The MBLKTAIL() macro calculates the number of bytes between the first unwritten byte and the last byte of the message block, that is: mp->b_datap->db_lim - mp->b_wptr.

The MBLKSIZE() macros calculates the total size of the message block, that is: mp->b_datap->db_lim - mp->b_datap->db_base.

The MBLKL() macro calculates the length of the message block, that is: mp->b_wptr - mp->b_rptr.

The MBLKIN() macro checks whether the byte range specified by offset and len resides entirely within the message block.

Return Values

The MBLKHEAD(), MBLKTAIL(), MBLKL() and MBLKSIZE() functions all return the appropriate byte count, as specified above. MBLKIN() returns non-zero if the check succeeds, or zero if it fails.

Context

These functions can be called from user, kernel or interrupt context.

Notes

These macros may evaluate any of their arguments more than once. This precludes passing arguments with side effects.

These macros assume the message itself is well formed, that is: mp->b_datap->db_base <= mp->b_rptr <= mp->b_wptr <= mp->b_datap->db_lim.

See Also

msgb(9S)

STREAMS Programming Guide