Kernel Functions for Drivers                           putctl(9F)



NAME
     putctl - send a control message to a queue

SYNOPSIS
     #include 



     int putctl(queuet *q, int type);


INTERFACE LEVEL
     Architecture independent level 1 (DI/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  MDATA,
     MPROTO, or MPCPROTO, 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 sendctl() routine is  used  to  pass  control  messages
     downstream. MBREAK messages are handled with putctl() (line
     11). putctl1(9F) (line 16) is used for MDELAY 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, cmnerr(9F) panics the system (line 21).





SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers                           putctl(9F)



       1  void
        2  sendctl(wrq, type, parm)
        3      queuet *wrq;
        4      uchart type;
        5      uchart parm;
        6  {
        7         extern int numallocfail;
        8
        9       switch (type) {
       10         case MBREAK:
       11             if (!putctl(wrq->qnext, MBREAK))
       12                      numallocfail];
       13               break;
       14
       15       case MDELAY:
       16             if (!putctl1(wrq->qnext, MDELAY, parm))
       17                      numallocfail];
       18             break;
       19
       20       default:
       21             cmnerr(CEPANIC, "sendctl: bad message type passed");
       22               break;
       23         }
       24  }


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


     Writing Device Drivers


     STREAMS Programming Guide




















SunOS 5.11          Last change: 16 Jan 2006                    2