1 files changed, 57 insertions, 0 deletions
diff --git a/semestr-5/so/lista2/so21_lista_2/cycle.c b/semestr-5/so/lista2/so21_lista_2/cycle.c
new file mode 100644
index 0000000..7daf754
--- /dev/null
+++ b/semestr-5/so/lista2/so21_lista_2/cycle.c
@@ -0,0 +1,57 @@
+#include "csapp.h"
+
+static void signal_handler(int signum, siginfo_t *info, void *data) {
+  if (signum == SIGINT) {
+    safe_printf("(%d) Screw you guys... I'm going home!\n", getpid());
+    _exit(0);
+  }
+}
+
+static void play(pid_t next, const sigset_t *set) {
+  for (;;) {
+    printf("(%d) Waiting for a ball!\n", getpid());
+    /* TODO: Something is missing here! */
+    sigset_t mask;
+    sigfillset(&mask);
+    sigdelset(&mask, SIGUSR1);
+    sigdelset(&mask, SIGINT);
+    Sigsuspend(&mask);
+    usleep((300 + random() % 400) * 1000);
+    Kill(next, SIGUSR1);
+    printf("(%d) Passing ball to (%d)!\n", getpid(), next);
+  }
+}
+
+int main(int argc, char *argv[]) {
+  if (argc != 2)
+    app_error("Usage: %s [CHILDREN]", argv[0]);
+
+  int children = atoi(argv[1]);
+
+  if (children < 4 || children > 20)
+    app_error("Give number of children in range from 4 to 20!");
+
+  /* Register signal handler for SIGUSR1 */
+  struct sigaction action = {.sa_sigaction = signal_handler};
+  Sigaction(SIGINT, &action, NULL);
+  Sigaction(SIGUSR1, &action, NULL);
+
+  /* TODO: Start all processes and make them wait for the ball! */
+  sigset_t mask;
+  sigfillset(&mask);
+  sigprocmask(SIG_BLOCK, &mask, NULL);
+
+  pid_t prev_pid = getpid();
+
+  for (int i = 1; i <= children; i++) {
+    int pid = Fork();
+    if (pid == 0) {
+      play(prev_pid, NULL);
+    }
+    prev_pid = pid;
+  } 
+
+  Kill(prev_pid, SIGUSR1);
+  play(prev_pid, NULL);
+  return EXIT_SUCCESS;
+}