This is a short program written for HACS408E that will generate a victory message for the sharedverbose binary.

bingo.c

#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

/*
 * This causes sharedverbose to print "bingo \o/" by modifying the shared
 * memory portion to give conditions in which the program will terminate
 * and give a victory message.
 *
 * gcc bingo.c -o bingo -lrt
 * ./bingo
 */

int main() {
  int fd = shm_open("/sharedverbose", 66, S_IRWXU);
  char payload[22] = {0};

  // Copy the winning payload in.
  strcpy(payload, "REVEN for 1337s");
  // Activate the 21st byte to terminate the infinite loop.
  payload[21] = 1;
  write(fd, payload, sizeof(payload));
  close(fd);

  // We wait for the second infinite loop to start...
  usleep(1000);
  // ...reopen the shared memory...
  fd = shm_open("/sharedverbose", 66, S_IRWXU);
  // ...and flip the 21st byte again to end the program.
  write(fd, payload, sizeof(payload));
  close(fd);
  return 0;
}