streamtab

This structure defines a module or a driver.

struct streamtab { struct qinit *st_rdinit; /* defines read queue */ struct qinit *st_wrinit; /* defines write queue */ struct qinit *st_muxrinit; /* for multiplexing */ struct qinit *st_muxwinit; /* drivers only */ };

QUEUE Structures

Two sets of queue structures form a module. The structures are queue, qinit, module_info, and module_stat (optional).

queue

The queue(9S) structure has the following format:

struct qinit *q_qinfo; /* procs and limits for queue */ struct msgb *q_first; /* msg que head for this queue */ struct msgb *q_last; /* msg queue tail for this queue */ struct queue *q_next; /* next queue in Stream */ struct queue *q_link /* to next Q for scheduling */ void *q_ptr; /* to private data structure */ ulong q_count; /* number of bytes in queue */ ulong q_flag; /* queue state */ long q_minpsz; /* min packet size accepted */ long q_maxpsz; /* max packet size accepted */ ulong q_hiwat; /* queue high water mark */ ulong q_lowat; /* queue low water mark */

When a queue pair is allocated, their contents are zero unless specifically initialized. The following fields are initialized:

• q_qinfo: st_rdinit and st_wrinit (or st_muxrinit and st_muxwinit) - from streamtab
• q_minpsz, q_maxpsz, q_hiwat, q_lowat - from module_info
• q_ptr - optionally, by the driver/module open routine

Queue flags from queue(9S)for queue structure are defined as:

#define QENAB 0x001 /* Queue is already enabled to run */ #define QWANTR 0x002 /* Someone wants to read Q */ #define QWANTW 0x004 /* Someone wants to write Q */ #define QFULL 0x008 /* Q is considered full */ #define QREADR 0x010 /* This is the reader (first) Q */ #define QUSE 0x020 /* This queue in use (allocation) */

#define QNOENB 0x040 /* Don't enable Q via putq */ #define QOLD 0x080 /* Pre-SVR4 open/close interface */ #define QBACK 0x100 /* queue has been back-enabled */

qinit

qinit(9S) format is as follows:

struct qinit { int (*qi_putp)(); /* put procedure */ int (*qi_srvp)(); /* service procedure */ int (*qi_qopen)(); /*called on each open or push*/ int (*qi_qclose)(); /*called on last close or pop*/ int (*qi_qadmin)(); /* reserved for future use */ struct module_info *qi_minfo; /* info struct */ struct module_stat *qi_mstat; /*stats struct (opt)*/ };

module_info

module_info (9S) has the following format:

struct module_info { ushort mi_idnum; /* module ID number */ char *mi_idname; /* module name */ long mi_minpsz; /* min packet size accepted */ long mi_maxpsz; /* max packet size accepted */ ulong mi_hiwat; /* high water mark, flow ctrl */ ulong mi_lowat; /* low water mark, flow ctrl */ };

qband

The queue flow information, qband (9S) for each band is contained in the following structure:

/* Structure that describes the separate information * for each priority band in the queue */ struct qband { struct qband *qb_next; /* next band's info */ ulong qb_count; /* number of bytes in band */ struct msgb *qb_first; /* beginning of band's data */ struct msgb *qb_last; /* end of band's data */ ulong qb_hiwat; /* high water mark for band */ ulong qb_lowat; /* low water mark for band */ ulong qb_flag; /* QB_FULL, denotes that a band of data flow is flow controlled */ };

Message Structures

A message is composed of a linked list of triples, consisting of two structures (msgb(9S) and datab(9S)) and a data buffer.

struct msgb { struct msgb *b_next; /*next msg on queue*/ struct msgb *b_prev; /*previous msg on queue*/ struct msgb *b_cont; /*next msg block of message*/ unsigned char *b_rptr; /*1st unread byte in bufr*/ unsigned char *b_wptr; /*1st unwritten byte in bufr*/ struct datab *b_datap; /*data block*/ unsigned char b_band; /*message priority*/ unsigned short b_flag; /*see below - Message flags*/ };typedef struct msgb mblk_t;

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Note - Modules or drivers cannot modify b_next and b_prev.These fields are modified by utility routines such as putq() and getq().

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Conceptually the band belongs in the message block since it is associated with the message and not just with the data. However, the size of a message block is visible to modules and drivers, so the band is placed in the data block instead. Modules and drivers should have no knowledge of the size of the data block.

struct datab { unsigned char *db_base; /* first byte of buffer */ unsigned char *db_lim; /* last byte+1 of buffer */ unsigned char db_ref; /* msg count ptg to this blk */ unsigned char db_type; /* msg type */ }; typedef struct datab dblk_t;

iocblk

This is contained in an M_IOCTL message block:

struct iocblk { int ioc_cmd; /* ioctl command type */ cred_t *ioc_cr; /* full credentials */ uint ioc_id; /* ioctl id */ uint ioc_count; /* count of bytes in data field */ int ioc_error; /* error code */ int ioc_rval; /* return value */ };

copyreq

This is used in M_COPYIN/M_COPYOUT messages:

struct copyreq { int cq_cmd; /* ioctl command (from ioc_cmd) */ cred_t *cq_cr; /* full credentials */

uint cq_id; /* ioctl id (from ioc_id) */ caddr_t cq_addr; /* address to copy data to/from */ uint cq_size; /* number of bytes to copy */ int cq_flag; /* see below */ mblk_t *cq_private; /* private state information */ };

copyresp

This structure is used in M_IOCDATA:

struct copyresp { int cp_cmd; /* ioctl command (from ioc_cmd) */ cred_t *cp_cr; /* full credentials */ uint cp_id; /* ioctl id (from ioc_id) */ caddr_t cp_rval; /* status of req; 0 for success non-zero for failure */ mblk_t *cp_private; /* private state info */ };

Other Structures

strioctl

This structure supplies user values as an argument to the ioctl call I_STR in streamio(7).

struct strioctl { int ic_cmd; /* downstream request */ int ic_timout; /*timeout acknowledgment-ACK/NAK*/ int ic_len; /* length of data argument */ char *ic_dp; /* pointer to data argument */ };

linkblk

This structure is used in lower multiplexer drivers to indicate a link

struct linkblk { queue_t *l_qtop; /* lowest level write queue for upper */ /* Stream, set to NULL for persist links */ queue_t *l_qbot; /* high level write q of lower Stream */ int l_index; /* system-unique index for lower Stream */ };

stroptions

his structure holds various values used by the SREAMS. system:

struct stroptions { ulong so_flags; /* options to set */ short so_readopt; /* read option */ ushort so_wroff; /* write offset */ long so_minpsz; /* minimum read packet size */ long so_maxpsz; /* maximum read packet size */ ulong so_hiwat; /* read queue high water mark */ ulong so_lowat; /* read queue low water mark */ unsigned charso_band; /* band for water marks */ }; /* flags for Stream options set message */ #define SO_ALL 0x003f /* set all options */ #define SO_READOPT 0x0001 /* set read option */ #define SO_WROFF 0x0002 /* set write offset */ #define SO_MINPSZ 0x0004 /* set minimum packet size */ #define SO_MAXPSZ 0x0008 /* set maximum packet size */ #define SO_HIWAT 0x0010 /* set high water mark */ #define SO_LOWAT 0x0020 /* set low water mark */ #define SO_MREADON 0x0040 /* set read notification on */ #define SO_MREADOFF 0x0080 /* set read notification off */ #define SO_NDELON 0x0100 /* old TTY semantics for NDELAY */ #define SO_NDELOFF 0x0200 /* STREAMS semantics for NDELAY */

#define SO_ISTTY 0x0400 /* Stream acting as terminal*/ #define SO_ISNTTY 0x0800 /* Stream not acting as term*/ #define SO_TOSTOP 0x1000 /* stop on bkgrnd writes*/ #define SO_TONSTOP 0x2000 /* don't stop on bkgrnd jobs*/ #define SO_BAND 0x4000 /* water marks affect band */ #define SO_DELIM 0x8000 /* messages are delimited */ #define SO_NODELIM 0x010000 /* turn off delimiters */ #define SO_STRHOLD 0x020000 /* strwrite msg coalescing */