Client-Server Communication using FIFOs for more then 1 clients

Client server project using 3 clients has been done. Below is the code for server :


#include"headers.h"
#include"prototypes.h"
#include"request.h"

void main()
{
int fd,ret,ac,*ptr,count1,sum,*ptr1;
char crfd[4],cwfd[4],crfd1[4],cwfd1[4];
request r;
ptr = creatpipe();

sprintf(crfd,"%d",*(ptr+0));
sprintf(cwfd,"%d",*(ptr+1));
sprintf(crfd1,"%d",*(ptr+2));
sprintf(cwfd1,"%d",*(ptr+3));





while(1)
{
fd = open("myfifo",O_RDONLY);
if(fd==-1)
{
perror("mkfifo");
exit(EXIT_FAILURE);
}
count1=read(fd,&r,sizeof(request));
if(count1==-1)
{
perror("read");
exit(EXIT_FAILURE);
}

count1 = write(*(ptr+1),&r,sizeof(request));
if(count1==-1)
{
perror("write");
exit(EXIT_FAILURE);
}
ret = fork();
switch(ret)
{
case 0:
invoke_req(ptr);
break;
default :
wait(&ac);
{
count1 = read(*(ptr+2),&sum,sizeof(int));
if(count1==-1)
{
perror("read");
exit(EXIT_FAILURE);
}

if(access("resfifo",F_OK)==-1)
{
mkfifo("resfifo",0666);
}
fd = open("resfifo",O_WRONLY);
count1 = write(fd,&sum,sizeof(int));
if(count1==-1)
{
perror("read");
exit(EXIT_FAILURE);
}
}
}
}
}
And client code is of following:


#include"headers.h"
#include"request.h"
int main()
{
request r;
int count,ret,count3,fd,fd1,result,ac;
r.opend1 = 20;
r.opend2 = 23;
r.opr = '*';
//r.pid = getpid():
if(access("myfifo",F_OK)==-1)
{
mkfifo("myfifo",0666);
}
fd = open("myfifo",O_WRONLY);
count3 = write(fd,&r,sizeof(request));
if(count3==-1)
{
perror("write");
exit(EXIT_FAILURE);
}
if(access("resfifo",F_OK)==-1)
{
mkfifo("resfifo",0666);
}

fd1 = open("resfifo",O_RDONLY);
count = read(fd1,&result,sizeof(int));
if(count==-1)
{
perror("read");
exit(EXIT_FAILURE);
}
printf("client seeking for multiply : %d\n",result);




return 0;
}

The issues are resolved by using semaphores,signal handlers. Semaphores are used at the shared region so that one process at a time can used the shared region and no over written of data occurs.

@rahul.kushwaha2695

Rahul check your Structure ! You have used used typedef and then giving the name 'd '
to structure ... Now this. 'd' will behave as a data type of your Structure.... Further you have assigned values just pointed by 'd' , this 'd' is a data type ....

You should give a variable name of your Structure ..
For Example...

d result
Now put values in this variable---

result.pid = getpid();
result.res = 100;

Then you should use this variable in your messagequeue like below :

msgsnd(msgid,&result,sizeof(result),IPC_NOWAIT);