wait.c

AnimalProcessing/Fundamentals/wait.c

@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <err.h>
+int fibo (int n){
+    
+    if (n <= 0) return 0;
+    else if (n <= 1) return 1;
+    else return fibo(n - 1) + fibo(n - 2);
+    
+}
+int wait_child(int x){
+
+    if(x < 0) return -1;
+
+    int wstatus;
+    pid_t pid = fork();
+
+    if(pid < 0) return -1;
+
+    // Child 
+    else if (pid == 0) {
+        
+       if (x < 0) exit(-1); 
+       
+       exit(fibo(x));
+    }
+
+    // Daddy
+    else {
+
+        if(waitpid(pid, &wstatus, 0) == -1) return -1;
+        
+        if(wstatus == -1) return -1;
+        
+        if (WIFEXITED(wstatus)){
+            int rslt = WEXITSTATUS(wstatus);
+
+            if (rslt == 255) rslt = -1;
+            
+            printf("My child knows how to count the Fibonacci sequence. He found %i for %i!\n",rslt, x);
+ 
+        }
+        
+        return 0;
+    }
+}
+/*
+int main(){
+    int res = wait_child(-1);
+printf("%d\n",  res);                       // -1
+
+res = wait_child(7);                        // 13
+printf("%d\n", res);                        // 0
+}*/