Manual Pages for UNIX Operating System command usage for man putctl

Kernel Functions for Drivers                           putctl(9F)



NAME
     putctl - send a control message to a queue

SYNOPSIS
     #include 



     int putctl(queue_t *q, int type);


INTERFACE LEVEL
     Architecture independent level 1 (DDI/DKI).

PARAMETERS
     q       Queue to which the message is to be sent.


     type    Message type (must be control, not data type).


DESCRIPTION
     The putctl() function tests the type argument to make sure a
     data type has not been specified, and then attempts to allo-
     cate a message block. putctl()  fails  if  type  is  M_DATA,
     M_PROTO, or M_PCPROTO, or if a message block cannot be allo-
     cated. If successful,  putctl() calls the put(9E) routine of
     the  queue pointed to by q with the newly allocated and ini-
     tialized messages.

RETURN VALUES
     On success, 1 is returned. If type is a data type, or  if  a
     message block cannot be allocated, 0 is returned.

CONTEXT
     The putctl() function can be called from user, interrupt, or
     kernel context.

EXAMPLES
     Example 1 Using putctl()


     The send_ctl() routine is  used  to  pass  control  messages
     downstream. M_BREAK messages are handled with putctl() (line
     11). putctl1(9F) (line 16) is used for M_DELAY messages,  so
     that parm can be used to specify the length of the delay. In
     either case, if a message block cannot be allocated a  vari-
     able  recording  the number of allocation failures is incre-
     mented (lines  12,  17).  If  an  invalid  message  type  is
     detected, cmn_err(9F) panics the system (line 21).





SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers                           putctl(9F)



       1  void
        2  send_ctl(wrq, type, parm)
        3      queue_t *wrq;
        4      uchar_t type;
        5      uchar_t parm;
        6  {
        7         extern int num_alloc_fail;
        8
        9       switch (type) {
       10         case M_BREAK:
       11             if (!putctl(wrq->q_next, M_BREAK))
       12                      num_alloc_fail++;
       13               break;
       14
       15       case M_DELAY:
       16             if (!putctl1(wrq->q_next, M_DELAY, parm))
       17                      num_alloc_fail++;
       18             break;
       19
       20       default:
       21             cmn_err(CE_PANIC, "send_ctl: bad message type passed");
       22               break;
       23         }
       24  }


SEE ALSO
     put(9E),     cmn_err(9F),     datamsg(9F),      putctl1(9F),
     putnextctl(9F)


     Writing Device Drivers


     STREAMS Programming Guide




















SunOS 5.11          Last change: 16 Jan 2006                    2