datab(9S)

NAME

     datab - STREAMS message data structure

SYNOPSIS

     #include <sys/stream.h>

INTERFACE LEVEL

     Architecture independent level 1 (DDI/DKI).

DESCRIPTION

     The datab structure describes the data of a STREAMS message.
     The  actual data contained in a STREAMS message is stored in
     a data buffer pointed to by this structure. A  msgb (message
     block)  structure  includes  a  field that points to a datab
     structure.

     Because a data block can have more than  one  message  block
     pointing to it at one time, the db_ref member keeps track of
     a data block's references, preventing it from being  deallo-
     cated until all message blocks are finished with it.

STRUCTURE MEMBERS

     unsigned char     *db_base;     /* first byte of buffer */
     unsigned char     *db_lim;      /* last byte (+1) of buffer */
     unsigned char      db_ref;      /* # of message pointers to this data */
     unsigned char      db_type;     /* message type */

     A datab structure is defined as type dblk_t.

SEE ALSO

     free_rtn(9S), msgb(9S)

     Writing Device Drivers

     STREAMS Programming Guide