Code:
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/msg.h>
#include <sys/ipc.h>
#include <sys/types.h>
#define MSGSZ 128
main ()
{
FILE *fp1, *fp2, *fp3;
char filename[70];
int remove_res;
int msqid, msqid1, msqid2, msqid3, msqidK;
int status;
int msgflg = IPC_CREAT | 0666;
key_t key;
key_t key1, key2, key3, keyK, keyK2;
size_t buf_length;
int pid_upost, pid1, pid2, pid3;
int temp, temp1, temp2, temp3, temp4, temp5;
int ans;
int i;
int c;
int maxmsgsz;
int msgsz;
struct msgbuf {
long mtype;
char mtext[MSGSZ];
long dest;
} *sbuf, *rbuf, *rbuf1, *rbuf2, *rbuf3, *rbufK, *rbufK2;
do
{
printf("\n\t\t1) Write a new message");
printf("\n\t\t2) View old messages");
printf("\n\t\t3) Delete old messages");
printf("\n\t\t4) Exit");
sbuf = (struct msgbuf*)malloc((unsigned)(sizeof(struct msgbuf) - sizeof sbuf->mtext + 128));
do
{
scanf("%d", &ans);
} while ((ans < 1) || (ans > 4));
key = ftok("/home/...../file.tmp", 'a');
if (msqid = msgget(key, msgflg) < 0)
{
perror("\nError (msgget)\n");
exit(-1);
}
buf_length = MSGSZ;
switch(ans) {
case 1:
{
sbuf->mtype = 1;
printf("\nType destination number ");
scanf("%d",&sbuf->dest);
if ((sbuf->dest < 1) || (sbuf->dest > 3))
{
printf("\nError: type 1, 2 or 3\n");
exit(-1);
}
printf("\nType a message): ");
while ((c = getchar()) != '\n' && c != EOF);
for (i = 0; ((c = getchar()) != '\n'); i++){
sbuf->mtext[i] = c;
}
sbuf->mtext[strlen(sbuf->mtext)] = '\0';
break;
}
case 2:
{
sbuf->mtype = 2;
printf("\nType destination number ");
scanf("%d", &sbuf->dest);
if ((sbuf->dest < 1) || (sbuf->dest > 3))
{
printf("\nError: type 1, 2 or 3\n");
exit(-1);
}
strcpy(sbuf->mtext, "View old messages ");
break;
}
case 3:
{
sbuf->mtype = 3;
printf("\nInsert file number : ");
scanf("%d", &sbuf->dest);
if ((sbuf->dest < 1) || (sbuf->dest > 3))
{
printf("\nError: type 1, 2 or 3\n");
exit(-1);
}
strcpy(sbuf->mtext, "Delete old messages ");
break;
}
case 4:
{
exit(0);
}
}
if (msgsnd(msqid, &sbuf, buf_length, IPC_NOWAIT) < 0)
{
perror("\nError (msgsnd)\n");
exit(-1);
}
pid_upost = fork();
if (pid_upost == 0)
{
rbuf = (struct msgbuf*)malloc((unsigned)(sizeof(struct msgbuf) - sizeof sbuf->mtext + 128));
temp = msgrcv(msqid, &rbuf, MSGSZ, 0, MSG_NOERROR);
if (temp < 0)
{
perror("\nError (msgrcv)\n");
exit(-1);
}
switch (rbuf->dest) {
case 1:
{
key1 = ftok("/home/...../file1.tmp", 'b');
if (msqid1 = msgget(key1, IPC_CREAT | 0666) < 0)
{
perror("\nError (msgget)\n");
exit(-1);
}
buf_length = MSGSZ;
if (msgsnd(msqid1, &rbuf, buf_length, IPC_NOWAIT) < 0)
{
perror("\nError (msgsnd)\n");
exit(-1);
}
pid1 = fork();
if (pid1 == 0)
{
rbuf1 = (struct msgbuf*)malloc((unsigned)(sizeof(struct msgbuf) - sizeof sbuf->mtext + 128));
temp1 = msgrcv(msqid1, &rbuf1, MSGSZ, 0, MSG_NOERROR);
if (temp1 < 0)
{
perror("\nError (msgrcv)\n");
exit(-1);
}
if ((fp1 = fopen("/home/...../Desktop/message1", "a")) == NULL)
{
printf("\nError (fopen)\n");
}
fprintf(fp1, "Destination: %d\n", rbuf1->dest);
fprintf(fp1, "Message: %s\n\n", rbuf1->mtext);
fclose(fp1);
rbufK = (struct msgbuf*)malloc((unsigned)(sizeof(struct msgbuf) - sizeof sbuf->mtext + 128));
rbufK->mtype = 4;
if (rbuf1->mtype == 3)
{
if (remove_res = remove("message1") != 0)
{
strcpy(rbufK->mtext, "File not deleted");
}
else
{
strcpy(rbufK->mtext, "File message1 deleted");
}
}
else
{
strcpy(rbufK->mtext, "Message inserted");
}
if (msgsnd(msqid1, &rbufK, buf_length, IPC_NOWAIT) < 0)
{
perror("\nError (msgsnd)\n");
exit(-1);
}
}
break;
}
case 2:
{
/*The same as above, but process pid2 is
created and file message2 is written*/
}
case 3:
{
/*The same as above, but process pid3 is
created and file message3 is written*/
}
}
waitpid(pid1, &status, 0);
rbufK2 = (struct msgbuf*)malloc((unsigned)(sizeof(struct msgbuf) - sizeof sbuf->mtext + 128));
temp4 = msgrcv(msqid1, &rbufK2, MSGSZ, 4, MSG_NOERROR);
if (temp4 < 0)
{
perror("\nError (msgrcv)\n");
exit(-1);
}
else
{
printf("\nMESSAGE %s RECEIVED\n", rbufK2->mtext);
}
}
waitpid(pid_upost, &status, 0);
}
while (ans != 4);
}
