Asignment 3

childsgame.c

@@ -0,0 +1,166 @@
+/* Write a C program to implement the following game.
+
+The parent program P first creates two pipes and then spawns two child processes
+C and D. One of the two pipes is meant for communication between P and C and the
+other one for communication between P and D. Now a loop runs as follows.
+
+In each iteration (also called a round), P first randomly chooses one of the
+flags MIN or MAX. The choices randomly varies from one iteration to another.
+Each of the two child processes C and D generates a random positive integer and
+sends that to P via its pipe. P reads the two integers. Let these be c and d
+respectively. If P has chosen MIN, then the child which sends the smaller of c
+and d gets one point and if P has chosen MAX, then the child which sends the
+larger of c and d gets one point. If c == d, then this round is ignored. The
+child process which first obtains 10 points wins the game.
+
+When the game ends, P sends a user-defined signal to both C and D and the child
+processes exit after handling the signal (in order to know who was the winner).
+After C and D exits, the parent process also exists. During each iteration of
+the game, P should also print appropriate messages like P's choice of flag,
+the integers received from C and D, which child gets the point, the current
+scores of C and D in order to let the user know how the game is going on.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/types.h>
+
+#define BUFSIZE 20
+#define WINNING_CONDITION 10
+
+static int stop = 0;
+
+// Custom signal handler to handle the termination of game
+void end_process(int sig) {
+  if (sig == SIGUSR1) {
+    stop = 1;
+  }
+  else if (sig == SIGUSR2) {
+    stop = 2;
+  }
+}
+
+int main() {
+  pid_t pid1, pid2;
+
+  // Create the pipe descriptors
+  int fd1[2], fd2[2];
+  pipe(fd1);
+  pipe(fd2);
+
+  // Assign the custom signal handler to SIGUSR1 signal
+  signal(SIGUSR1, end_process);
+  signal(SIGUSR2, end_process);
+
+  if ((pid1 = fork()) == 0) {
+    // Child 1
+    srand((unsigned int)time(NULL) ^ getpid());
+    close(fd1[0]);  // Close the read end as the child will not read
+
+    // Generate a random number and place it on the pipe
+    while(!stop) {
+      int n = rand() % 100;
+      char line[BUFSIZE];
+      sprintf(line, "%d", n);
+      write(fd1[1], line, BUFSIZE);
+    }
+
+    // Handle the exit of the child process by displaying proper message
+    if (stop == 1) {
+      printf("C: I am the winner\n");
+    } else if (stop == 2) {
+      printf("C: D is the winner\n");
+    }
+    printf("Exiting from child C\n\n");
+
+  } else {
+    if ((pid2 = fork()) == 0) {
+      // Child 2
+      srand((unsigned int)time(NULL) ^ getpid());
+      close(fd2[0]);  // Close the read end as the child will not read
+
+      // Generate a random number and place it on the pipe
+      while(!stop) {
+        int n = rand() % 100;
+        char line[BUFSIZE];
+        sprintf(line, "%d", n);
+        write(fd2[1], line, BUFSIZE);
+      }
+
+      // Handle the exit of the child process by displaying proper message
+      if (stop == 1) {
+        printf("D: C is the winner\n");
+      } else if (stop == 2) {
+        printf("D: I am the winner\n");
+      }
+      printf("Exiting from child D\n\n");
+
+    } else {
+      // Parent
+      close(fd1[1]);
+      close(fd2[1]);  // Close the write ends as the parent will not read
+
+      srand((unsigned int)time(NULL) ^ getpid());
+      int round = 1;
+      int score1 = 0, score2 = 0;
+      char line[BUFSIZE];
+      char winner;
+      int num1, num2, choice;
+
+      while (1) {
+        printf("Round number: %d\n", round++);
+
+        choice = rand() % 2;  // P chooses a flag: 0 for MAX and 1 for MIN
+
+        // Read and print the first integer from the pipe
+        read(fd1[0], line, BUFSIZE);
+        sscanf(line, "%d", &num1);
+        printf("Integer received from C: %d\n", num1);
+
+        // Read and print the second integer from the pipe
+        read(fd2[0], line, BUFSIZE);
+        sscanf(line, "%d", &num2);
+        printf("Integer received from D: %d\n", num2);
+
+        // Choose the winner for the round and add to its point
+        if (choice) {
+          printf("P's choice of flag: MIN\n");
+        } else {
+          printf("P's choice of flag: MAX\n");
+        }
+        if (num1 == num2)
+          printf("This round is a tie!\n");
+        else if ((num1 < num2 && choice) || (num1 > num2 && !choice)) {
+          printf("C gets the point\n");
+          score1++;
+        } else {
+          printf("D gets the point\n");
+          score2++;
+        }
+        printf("Updated scores: C = %d, D = %d\n\n", score1, score2);
+
+        // Break when score of any child becomes 10
+        if (score1 == WINNING_CONDITION || score2 == WINNING_CONDITION)
+          break;
+      }
+
+      // Send appropriate singal to the children to let them know who the winner was
+      if (score1 > score2) {
+        kill(pid1, SIGUSR1);
+        kill(pid2, SIGUSR1);
+      } else {
+        kill(pid1, SIGUSR2);
+        kill(pid2, SIGUSR2);
+      }
+
+      // Wait for the children to terminate and then terminate the parent
+      waitpid(pid1, &num1, 0);
+      waitpid(pid2, &num2, 0);
+      printf("Exiting from parent P\n");
+    }
+  }
+  return 0;
+}