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#include <unistd.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <sys/shm.h>

#define TEXT_SZ 2048

struct shared_use_st{

int written;

char text[TEXT_SZ];

};

int main(){

int shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666 | IPC_CREAT);

if(shmid == -1){

fprintf(stderr, "shmget failed \n");

exit(EXIT_FAILURE);

}

void *shared_memory = shmat(shmid, (void *)0, 0);

if(shared_memory == (void *)-1){

fprintf(stderr, "shmat failed \n");

exit(EXIT_FAILURE);

}

printf("memory attached at : % ld \n", (long)shared_memory);

struct shared_use_st *shared_stuff = (struct shared_use_st *)shared_memory;

shared_stuff->written = 0;

char buffer[TEXT_SZ];

int running = 1;

while(running){

while(shared_stuff->written == 1){

sleep(1);

printf("waiting for client \n");

}

printf("enter some text \n");

fgets(buffer, TEXT_SZ, stdin);

strncpy(shared_stuff->text, buffer, TEXT_SZ);

shared_stuff->written = 1;

if(strncmp(buffer, "end", 3) == 0){

running = 0;

}

}

if(shmdt(shared_memory) == -1){

fprintf(stderr, "shmdt failed \n");

exit(EXIT_FAILURE);

}

return 0;

}