Category : Files from Magazines
Archive : PCTJ1288.ZIP
Filename : QDEMO1.C
Output of file : QDEMO1.C contained in archive : PCTJ1288.ZIP
* Copyright (c) 1988 PC Tech Journal and Ziff-Davis Publishing Co.
* Written by Ted Mirecki
*/
#define INCL_DOS /* include all DOS* function prototypes */
#include
/* Q item type codes: */
#define I_NUM 0 /* long int, not pointer */
#define I_NAME 1 /* ptr to named shared mem */
#define I_OWN 2 /* ptr to owner's memory (given) */
#define I_DISJ 3 /* ptr to disjoint memory (gettable) */
char fmt[20]; /* Format string for progress messages */
char Pname[] = "QDEMO2.EXE";
char Qname[] = "\\QUEUES\\TEST00.Q";
char Mname[] = "\\SHAREMEM\\TEST00.SEG";
struct {
char arg0[sizeof(Pname)];
char arg1[sizeof(Qname)];
char arg2[sizeof(Mname)];
} args;
SEL NamedSeg; /* selector of named shared memory */
HQUEUE Qhan; /* handle of queue */
int err;
PID progid; /* process ID of this program */
main()
{
LINFOSEG far *local; /* ptr to Local Info seg */
SEL Gseg, Lseg; /* selectors for info segs*/
char far *outmsg;
char missing[65]; /* returned values from DosExecPgm */
RESULTCODES results;
/******************************************************************
INITIALIZE: create the queue, allocate named shared memory
******************************************************************/
DosGetInfoSeg(&Gseg, &Lseg); /* get info segments */
local = MAKEP(Lseg, 0);
progid = local->pidCurrent;
sprintf(fmt, "Process %d: %%s\n", progid); /* create format string */
printf(fmt, "Parent process started");
/* Create the Q */
err = DosCreateQueue(&Qhan, 2, Qname);
if (err) errmsg ("Create Q", err); /* won't return */
printf(fmt, "Queue created");
/* Allocate shared memory */
#define NamedLen 8000
err = DosAllocShrSeg(NamedLen, Mname, &NamedSeg);
if (err) errmsg("Alloc Share", err);
err = DosSubSet(NamedSeg, 1, NamedLen);
if (err) errmsg("Sub Set", err);
printf(fmt, "Named shared memory allocated");
/******************************************************************
EXEC a child process, passing names of Q & memory.
Continue reading until child passes termination value.
******************************************************************/
strcpy(args.arg0, Pname); /* build arg string */
strcpy(args.arg1, Qname);
args.arg1[sizeof(Qname)-1] = ' ';
strcpy(args.arg2, Mname);
err = DosExecPgm(missing, /* buffer for missing name */
sizeof(missing), /* its length */
EXEC_ASYNC, /* don't wait for child */
&args, 0L, /* args, same environment */
&results, /* place for returned values */
Pname); /* name of program */
if (err) errmsg("Exec", err);
while (Qread()) {
printf(fmt, "Press return to continue\n");
fgetchar();
}
DosCloseQueue(Qhan);
printf(fmt, "Good-bye from parent process");
}
/******************************************************************
QREAD(): Read from Q, with wait; determine message type, display
******************************************************************/
Qread()
{
struct {
PID writer; /* ID of writing process */
int type; /* event ID = type of ptr to Q item: */
} Qid;
union {
char far *msg; /* pointer to received message */
long value; /* value if item not a pointer */
} Qitem;
SEL msgseg; /* segment of message */
USHORT msgoff; /* offset of message */
char far *Qtext; /* pointer to message text */
int msglen; /* other element components */
char msgprio;
err = DosReadQueue(Qhan, &Qid,
&msglen, &Qitem,
0, /* read item at head of Q */
DCWW_WAIT, /* wait if Q empty */
&msgprio, /* priority of item */
0L); /* no semaphore ID */
if (err) errmsg("Read Q", err);
printf(fmt, "Read Q item:");
printf(" from Process %d\n", Qid.writer);
printf(" pointer type %d\n", Qid.type);
printf(" priority %d\n", (int) msgprio);
printf(" length %d\n", msglen);
switch (Qid.type) {
case I_NUM: {
printf(" Long value %ld\n", Qitem.value);
return (0);
}
case I_NAME: {
msgoff = OFFSETOF(Qitem.msg);
Qtext = MAKEP(NamedSeg, msgoff);
printf(" Message text:\n%s\n\n", Qtext);
err = DosSubFree(NamedSeg, msgoff, msglen);
if (err) errmsg("Sub Free", err);
break;
}
case I_OWN: {
printf(" Message text:\n%s\n\n", Qitem.msg);
DosFreeSeg(SELECTOROF(Qitem.msg) );
break;
}
case I_DISJ: {
msgseg = SELECTOROF(Qitem.msg);
err = DosGetSeg(msgseg);
if (err) errmsg("Get Seg", err);
printf(" Message text:\n%s\n\n", Qitem.msg);
DosFreeSeg(msgseg);
}
} /* end of switch */
return (Qid.type);
}
/******************************************************************
ERRMSG: Print error message, terminate process
******************************************************************/
errmsg( char *func, USHORT err)
{
printf("Process %d: Error %d in %s", progid, err, func);
DosCloseQueue(Qhan);
exit(1);
}
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