Finish assignment 2

Assignment2/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.22)
+cmake_minimum_required(VERSION 3.20)
 project(Assignment2 C)
 
 set(CMAKE_C_STANDARD 99)

Assignment2/main.c

@@ -1,21 +1,21 @@
 #include <stdio.h>
 #include <unistd.h>
-#include <sys/types.h>
 #include <string.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <wait.h>
+#include <limits.h>
 
-void print_prompt() {
+#define MAX_ARGS 6 // 5 arguments and a null pointer
-    printf("[%d]> ", getpid());
+
+void print_prompt(char *prompt) {
+    printf("(%d) %s", getpid(), prompt);
 }
 
 void one_child() {
-    print_prompt();
+    print_prompt("Hello, I am a parent process\n");
-    printf("Hello, I am a parent process\n");
     if (fork() == 0) { // Child process
-        print_prompt();
+        print_prompt("Hello, I am a child process\n");
-        printf("Hello, I am a child process\n");
         exit(0);
     } else { // Parent process
         wait(NULL);
@@ -37,8 +37,8 @@ void add_numbers() {
             // Add the number to the subtotal
             subtotal += number;
 
-            print_prompt();
+            print_prompt("The subtotal is ");
-            printf("The subtotal is %d\n", subtotal);
+            printf("%d\n", subtotal);
 
             // Write the sum to the receive_from_child pipe
             write(receive_from_child[1], &subtotal, sizeof(int));
@@ -47,16 +47,15 @@ void add_numbers() {
     } else { // Parent process
         int total = 0;
         while (number != 0) {
-            print_prompt();
+            print_prompt("Please input a number, 0 to terminate:\n");
-            printf("Please input a number, 0 to terminate:  ");
             // Read the number from the user, and convert it to an int
             char buffer[100];
             fgets(buffer, 100, stdin);
             number = atoi(buffer);
 
             // Display what was entered
-            print_prompt();
+            print_prompt("You entered: ");
-            printf("You entered %d\n", number);
+            printf("%d\n", number);
 
             // Write to child process
             write(send_to_child[1], &number, sizeof(int));
@@ -65,8 +64,8 @@ void add_numbers() {
             read(receive_from_child[0], &total, sizeof(int));
         }
         wait(NULL);
-        print_prompt();
+        print_prompt("The total is ");
-        printf("The total is %d\n", total);
+        printf("%d\n", total);
     }
     close(send_to_child[0]);
     close(send_to_child[1]);
@@ -74,17 +73,94 @@ void add_numbers() {
     close(receive_from_child[1]);
 }
 
+void free_exec(char *buffer, char **subcommand) {
+    free(buffer);
+    for (int i = 0; i < MAX_ARGS; i++) {
+        free(subcommand[i]);
+    }
+    free(subcommand);
+}
+
+void exec() {
+    print_prompt("Please input exec subcommand:\n");
+
+    char *buffer = calloc(100, sizeof(char)); // input buffer size 100
+    char **subcommand = calloc(6, sizeof(char *)); //size 6 to allow for 5 arguments and a null pointer
+    for (int i = 0; i < MAX_ARGS; i++) {
+        subcommand[i] = NULL;     //make sure each pointer is a null pointer
+    }
+    for (int i = 0; i < MAX_ARGS; i++) {
+        fgets(buffer, 100, stdin);
+        buffer[strcspn(buffer, "\n")] = 0; // Remove trailing newline
+        if (strcmp(buffer, ";") == 0) { // end of command, do not add to subcommand
+            break;
+        }
+        char *arg = calloc(strlen(buffer), sizeof(char) + 1); //allocate memory for argument of exact size
+        strncpy(arg, buffer, strlen(buffer)); //copy buffer into arg
+        subcommand[i] = arg; //add arg to subcommand
+    }
+
+    if (fork() == 0) { // Child process
+        execvp(subcommand[0], subcommand);
+        exit(0);
+    } else { // Parent process
+        wait(NULL);
+        free_exec(buffer, subcommand); //needs to be after wait to not use after free
+    }
+}
+
+int numPlaces(int n) {
+    if (n < 0) n = (n == INT_MIN) ? INT_MAX : -n;
+    if (n < 10) return 1;
+    if (n < 100) return 2;
+    if (n < 1000) return 3;
+    if (n < 10000) return 4;
+    if (n < 100000) return 5;
+    if (n < 1000000) return 6;
+    if (n < 10000000) return 7;
+    if (n < 100000000) return 8;
+    if (n < 1000000000) return 9;
+    return 10;
+}
+
+int pow2(int num) {
+    int ret = 2;
+    for (int i = 0; i < num - 1; i++) {
+        ret *= 2;
+    }
+    return ret;
+}
+
+void processtree() {
+    print_prompt("Please input a number:\n");
+    char buffer[100];
+    fgets(buffer, 100, stdin);
+    int number = atoi(buffer);
+    int power = pow2(number);
+    int string_length = numPlaces(power);
+
+    print_prompt("The value is 0\n");
+    for (int i = 1; i < power; i++) {
+        if (fork() == 0) { // Child process
+            char num[string_length];
+            sprintf(num, "The value is %d\n", i);
+            print_prompt(num);
+            exit(0);
+        } else {
+            wait(NULL);
+        }
+    }
+}
+
 int main() {
-    bool is_looping = true;
-
     // Listen loop
-    while (is_looping) {
+    while (true) {
-        print_prompt();
+        print_prompt("Please input a shell command:\n");
-
         char input[100];
         fgets(input, 100, stdin); // Input for commands
+
         if (strcmp(input, "stop\n") == 0) { // Stop command
-            is_looping = false;
+            break;
         }
         if (strcmp(input, "onechild\n") == 0) { // One child command
             one_child();
@@ -92,23 +168,11 @@ int main() {
         if (strcmp(input, "addnumbers\n") == 0) { // Add numbers command
             add_numbers();
         }
-        if (strcmp(input, "exec\n") == 0) {
+        if (strcmp(input, "exec\n") == 0) { // Exec command
-            char *args[2];
+            exec();
-            args[0] = "/bin/ls";
+        }
-            args[1] = NULL;
+        if (strcmp(input, "processtree\n") == 0) { // Process tree command
-            execv(args[0], args);
+            processtree();
         }
     }
 }
-
-void temp() {
-    char input[5][100];
-    char buffer[500];
-    //Print prompt
-    print_prompt();
-    if (fgets(buffer, 500, stdin) == NULL) {
-        exit(0);
-    }
-    //split buffer on spaces into input array
-    sscanf(buffer, "%s %s %s %s %s", input[0], input[1], input[2], input[3], input[4]);
-}