Andrew Ghobrial -- Processes

ex1/ex1.c

@@ -9,6 +9,23 @@
 int main(void)
 {
     // Your code here
+    int x = 100;
+    int rc = fork();
 
+    if (rc < 0)
+    {
+        fprintf(stderr, "fork failed\n");
+        exit(1);
+    }
+    else if (rc == 0)
+    {
+        // x = 20;
+        printf("Child x:%d \n", x);
+    }
+    else
+    {
+        x = 200;
+        printf("Parent x:%d \n", x);
+    }
     return 0;
 }

ex2/ex2.c

@@ -9,6 +9,38 @@
 int main(void)
 {
     // Your code here 
-
+    FILE *file;
+    // int rc = fork(); Having fork here will overwrite th file
+    file = fopen("text.txt", "w");
+    if (file == NULL)
+    {
+        printf("Could not open text.txt");
+        exit(1);
+    }
+    int fileNum;
+    fileNum = fileno(file);
+    printf("Pointer: %d\n", fileNum);
+
+    int rc = fork();
+    if (rc < 0)
+    {
+        fprintf(stderr, "fork failed\n");
+        exit(1);
+    }
+    else if (rc == 0)
+    {
+        char *txt = "Child.";
+        fprintf(file, "Child: %s", txt);
+
+        printf("Child descriptor: %d\n", fileNum);
+    }
+    else
+    {
+        char *txt = "Parent.";
+        fprintf(file, "Child %s", txt);
+        printf("Parent descriptor: %d\n", fileNum);
+    }
+
+    fclose(file);
     return 0;
 }

ex3/ex3.c

@@ -10,6 +10,20 @@
 int main(void)
 {
     // Your code here
-
+    int child_process = fork();
+    if (child_process < 0)
+    {
+        fprintf(stderr, "Fork failed\n");
+        exit(1);
+    }
+    else if (child_process == 0)
+    {
+        printf("hello.\n");
+    }
+    else
+    {
+        int wc = waitpid(child_process, NULL, 0);
+        printf("goodbye.\n");
+    }
     return 0;
 }

ex4/ex4.c

@@ -11,6 +11,26 @@
 int main(void)
 {
     // Your code here    
+    int child = fork();
+
+    if (child < 0)
+    {
+        printf("\nFork failed\n");
+    }
+    else if (child == 0)
+    {
+        char *args[2];
+        args[0] = "/bin/ls";
+        args[1] = NULL;
+
+        execvp(args[0], args);
+        printf("\nNot found\n");
+    }
+    else
+    {
+        int wc = waitpid(child, NULL, 0);
+        printf("\nParent\n");
+    }
 
     return 0;
 }

ex5/ex5.c

@@ -17,6 +17,23 @@ char* msg3 = "hello world #3";
 int main(void)
 {
     // Your code here
-
+    char s[MSGSIZE];
+    int p[2];
+
+    if (pipe(p) < 0)
+    {
+        fprintf(stderr, "\npipe error\n");
+        exit(1);
+    }
+
+    write(p[1], msg1, MSGSIZE);
+    write(p[1], msg2, MSGSIZE);
+    write(p[1], msg3, MSGSIZE);
+
+    for (int i = 0; i < 3; i++)
+    {
+        read(p[0], s, MSGSIZE);
+        printf("%s\n", s);
+    }
     return 0;
 }

ex6/ex6.c

@@ -21,6 +21,18 @@ and `clock_gettime()` should work just fine.
 int main()
 {
     // Your code here
-
+    int time = 0;
+    for (int i = 0; i < number_iter; i++)
+    {
+        struct timespec start, end;
+        clock_gettime(CLOCK_MONOTONIC, &start);
+        write(fileno(stdout), NULL, 0);
+        clock_gettime(CLOCK_MONOTONIC, &end);
+
+        time += BILLION * (end.tv_sec - start.tv_sec) + end.tv_nsec - start.tv_nsec;
+    }
+    time /= number_iter;
+
+    printf("\nAverage time: %d nanoseconds\n", time);
     return 0;
 }