Processes - Pedro Montesinos

ex1/ex1.c

@@ -9,6 +9,16 @@
 int main(void)
 {
     // Your code here
+    int x = 100;
+    if(fork() == 0){
+        x = 30;
+        printf("Child %i\n", x);
+    }else{
+        x = 20;
+        printf("Parent %i\n", x);
+    }
 
     return 0;
 }
+
+//A: the variable will be unique to each instance when the variable value is changed

ex2/ex2.c

@@ -9,6 +9,19 @@
 int main(void)
 {
     // Your code here 
-
+    FILE * file;
+    file = fopen("text.txt", "r+");
+
+    if (fork() == 0){
+        fprintf(file, "%s", "child!");
+        printf("child: %d\n", fileno(file));
+    }else{
+        fprintf(file, "%s", "parent");
+        printf("parent %d\n", fileno(file));
+    }
+    fclose(file);
     return 0;
 }
+
+
+// A: Yes the child and the parent can access the file descriptor returned by fopen and they both get written in!

ex2/text.txt

@@ -0,0 +1 @@
+parentchild!

ex3/ex3.c

@@ -10,6 +10,12 @@
 int main(void)
 {
     // Your code here
-
+    int temp = fork();
+    wait(NULL);
+    if(temp == 0){
+        printf("Child -> Hello \n");
+    }else{
+        printf("Parent -> Goodbye \n");
+    }
     return 0;
 }

ex4/ex4.c

@@ -10,7 +10,22 @@
 
 int main(void)
 {
-    // Your code here    
+    // Your code here
+    int temp = fork();
+    if(temp == 0){
+        char *args[2];
+        args[0] = "bin/ls";
+        args[1] = NULL;
+        execvp(args[0], args);
+        printf("Child process\n");
 
+    }else if(temp < 0){
+        printf("fork failed\n");
+    }
+    else
+    {
+        int wc = waitpid(temp, NULL, 0);
+        printf("Completed child process\n");
+    }
     return 0;
 }

ex5/ex5.c

@@ -17,6 +17,25 @@ char* msg3 = "hello world #3";
 int main(void)
 {
     // Your code here
+    char buffer[MSGSIZE];
+    int p[2];
+    if(pipe(p) < 0){
+        fprintf(stderr, "error error error\n");
+        exit(1);
+    }
 
+    int temp = fork();
+    if(temp == 0){
+        write(p[1], msg1, MSGSIZE);
+        write(p[1], msg2, MSGSIZE);
+        write(p[1], msg3, MSGSIZE);
+    }
+    else{
+        for (int i = 0; i < 3; i++){
+            read(p[0], buffer, MSGSIZE);
+            printf("%s\n", buffer);
+        }
+    }
+
     return 0;
-}
+}

ex6/ex6.c

@@ -21,6 +21,14 @@ and `clock_gettime()` should work just fine.
 int main()
 {
     // Your code here
-
+    int timed = 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);
+        timed += BILLION * (end.tv_sec - start.tv_sec) + end.tv_sec - start.tv_sec;
+    }
+    printf("%d\n", timed / number_iter);
     return 0;
-}
+}