Updated writeup again

Module/helper.sh

@@ -0,0 +1,36 @@
+#!/bin/bash
+
+MODULE_NAME="tempMonitor"
+DEVICE_NAME="/dev/temp_monitor"
+
+echo "What would you like to do?"
+echo "1. Install"
+echo "2. Uninstall"
+read -p "Enter option [1 or 2]: " option
+
+case $option in
+    1)
+        echo "Installing the kernel module..."
+        make clean
+        make
+        sudo rmmod $MODULE_NAME 2>/dev/null
+        sudo insmod ${MODULE_NAME}.ko
+        MAJOR_NUMBER=$(sudo dmesg | grep "temp_monitor: Device initialized with major number" | tail -1 | awk '{print $NF}')
+        if [ -z "$MAJOR_NUMBER" ]; then
+            echo "Failed to get major number from dmesg. Aborting."
+            exit 1
+        fi
+        sudo mknod $DEVICE_NAME c $MAJOR_NUMBER 0
+        sudo chmod 666 $DEVICE_NAME
+        echo "Module installed and device file created successfully."
+        ;;
+    2)
+        echo "Uninstalling the kernel module..."
+        sudo rmmod $MODULE_NAME
+        sudo rm -f $DEVICE_NAME
+        echo "Module and device file removed successfully."
+        ;;
+    *)
+        echo "Invalid option."
+        ;;
+esac

Module/tempMonitor.c

@@ -1,82 +1,191 @@
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/fs.h>
-#include <linux/uaccess.h>
-#include <linux/ioctl.h>
+/**************************************************************
+ * Class::  CSC-415-01 Fall 2024
+ * Name::  Uzair Hamed Mohammed
+ * Student ID::  920142896
+ * GitHub-Name::  gamersekofy
+ * Project:: Assignment 6 - Device Driver
+ *
+ * File:: tempMonitor.c
+ *
+ * Description::  This is a complex kernel module that retrieves CPU temperature
+ *data from /sys/class/thermal/thermal_zone*\/temp
+ *
+ **************************************************************/
+
 #include <linux/device.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/ioctl.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/uaccess.h>
 
 #define DEVICE_NAME "temp_monitor"
 #define IOCTL_GET_TEMP _IOR('t', 1, int)
 
-static int temp = 0;
+// The CPU temperature will be accessed from thermal_zone0/temp
+#define TEMP_SENSOR_PATH "/sys/class/thermal/thermal_zone0/temp"
+#define BUF_LEN 100
+
 static int major_number;
-static struct class* temp_monitor_class = NULL;
-static struct device* temp_monitor_device = NULL;
+static struct class *temp_monitor_class = NULL;
+static struct device *temp_monitor_device = NULL;
+static char temp_unit[BUF_LEN] = "C"; // Default unit is Celsius
 
-static int device_open(struct inode *inode, struct file *file) {
-    return 0;
-}
+/* A similar flag exists in the test/user application. If it's detected that
+ * the user is in a virtual machine, a smulated temperature is returned */
+static bool simulate_temp = false;
 
-static int device_release(struct inode *inode, struct file *file) {
-    return 0;
-}
+static int device_open(struct inode *inode, struct file *file) { return 0; }
 
-static long device_ioctl(struct file *file, unsigned int cmd, unsigned long arg) {
-    switch (cmd) {
-        case IOCTL_GET_TEMP:
-            // Simulate reading temperature
-            temp = 50; // Example temperature
-            if (copy_to_user((int *)arg, &temp, sizeof(temp))) {
-                return -EACCES;
-            }
-            break;
-        default:
-            return -EINVAL;
+static int device_release(struct inode *inode, struct file *file) { return 0; }
+
+static ssize_t device_read(struct file *file, char __user *buffer, size_t len,
+                           loff_t *offset) {
+  int temp = 0;
+  char temp_str[BUF_LEN];
+  struct file *f;
+  char *buf;
+  loff_t pos = 0;
+  bool is_simulated = false;
+
+  // Check if the temperature file exists. If it doesn't, simulate the
+  // temperature.
+  f = filp_open(TEMP_SENSOR_PATH, O_RDONLY, 0);
+  if (IS_ERR(f)) {
+    printk(KERN_INFO "temp_monitor: Temperature file not found\n");
+    is_simulated = true;
+    get_random_bytes(&temp, sizeof(temp));
+    // Simulate a temperature between 10 and 50 degrees
+    temp = (temp % 40) + 10;
+  } else {
+    buf = kmalloc(16, GFP_KERNEL);
+    if (!buf) {
+      filp_close(f, NULL);
+      return -ENOMEM;
     }
-    return 0;
+
+    // Read the temperature
+    kernel_read(f, buf, 16, &pos);
+    sscanf(buf, "%d", &temp);
+    // Convert to degrees Celsius
+    temp /= 1000;
+    filp_close(f, NULL);
+    kfree(buf);
+  }
+
+  // Convert to desired unit
+  if (strcmp(temp_unit, "F") == 0) {
+    temp = temp * 9 / 5 + 32;
+    // Convert to Fahrenheit
+  } else if (strcmp(temp_unit, "K") == 0) {
+    temp += 273;
+    // Convert to Kelvin
+  }
+
+  snprintf(temp_str, BUF_LEN, "%d %s%s\n", temp, temp_unit,
+           is_simulated ? " (simulated temperature)" : "");
+
+  // Copy the result to user-space
+  if (copy_to_user(buffer, temp_str, strlen(temp_str) + 1)) {
+    return -EFAULT;
+  }
+
+  return strlen(temp_str) + 1;
+}
+
+static ssize_t device_write(struct file *file, const char __user *buffer,
+                            size_t len, loff_t *offset) {
+  char msg[BUF_LEN];
+
+  // Check if input too long
+  if (len > BUF_LEN - 1) {
+    return -EINVAL;
+  }
+
+  if (copy_from_user(msg, buffer, len)) {
+    return -EFAULT;
+  }
+  msg[len] = '\0';
+
+  if (strcmp(msg, "simulate") == 0) {
+    simulate_temp = true;
+  } else {
+    simulate_temp = false;
+    strncpy(temp_unit, msg, BUF_LEN - 1);
+  }
+
+  printk(KERN_INFO "temp_monitor: Write operation: %s\n", msg);
+
+  return len;
+}
+
+static long device_ioctl(struct file *file, unsigned int cmd,
+                         unsigned long arg) {
+  switch (cmd) {
+  case IOCTL_GET_TEMP: {
+    int temp = 0;
+    // Retrieve the temperature data
+    if (copy_to_user((int *)arg, &temp, sizeof(temp))) {
+      return -EACCES;
+    }
+    break;
+  }
+  default:
+    return -EINVAL;
+  }
+  return 0;
 }
 
 static struct file_operations fops = {
     .open = device_open,
     .release = device_release,
+    .read = device_read,
+    .write = device_write,
     .unlocked_ioctl = device_ioctl,
 };
 
 static int __init temp_monitor_init(void) {
-    major_number = register_chrdev(0, DEVICE_NAME, &fops);
-    if (major_number < 0) {
-        printk(KERN_ALERT "temp_monitor: Failed to register a major number\n");
-        return major_number;
-    }
-    temp_monitor_class = class_create(DEVICE_NAME);
-    if (IS_ERR(temp_monitor_class)) {
-        unregister_chrdev(major_number, DEVICE_NAME);
-        printk(KERN_ALERT "temp_monitor: Failed to register device class\n");
-        return PTR_ERR(temp_monitor_class);
-    }
-    temp_monitor_device = device_create(temp_monitor_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
-    if (IS_ERR(temp_monitor_device)) {
-        class_destroy(temp_monitor_class);
-        unregister_chrdev(major_number, DEVICE_NAME);
-        printk(KERN_ALERT "temp_monitor: Failed to create the device\n");
-        return PTR_ERR(temp_monitor_device);
-    }
-    printk(KERN_INFO "temp_monitor: Device initialized with major number %d\n", major_number); // Added this line
-    return 0;
+  major_number = register_chrdev(0, DEVICE_NAME, &fops);
+  if (major_number < 0) {
+    printk(KERN_ALERT "temp_monitor: Failed to register a major number\n");
+    return major_number;
+  }
+  temp_monitor_class = class_create(THIS_MODULE->name); // Updated this line
+  if (IS_ERR(temp_monitor_class)) {
+    unregister_chrdev(major_number, DEVICE_NAME);
+    printk(KERN_ALERT "temp_monitor: Failed to register device class\n");
+    return PTR_ERR(temp_monitor_class);
+  }
+  temp_monitor_device = device_create(
+      temp_monitor_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
+  if (IS_ERR(temp_monitor_device)) {
+    class_destroy(temp_monitor_class);
+    unregister_chrdev(major_number, DEVICE_NAME);
+    printk(KERN_ALERT "temp_monitor: Failed to create the device\n");
+    return PTR_ERR(temp_monitor_device);
+  }
+  printk(KERN_INFO "temp_monitor: Device initialized with major number %d\n",
+         major_number);
+  return 0;
 }
 
 static void __exit temp_monitor_exit(void) {
-    device_destroy(temp_monitor_class, MKDEV(major_number, 0));
-    class_unregister(temp_monitor_class);
-    class_destroy(temp_monitor_class);
-    unregister_chrdev(major_number, DEVICE_NAME);
-    printk(KERN_INFO "temp_monitor: Device removed\n");
+  device_destroy(temp_monitor_class, MKDEV(major_number, 0));
+  class_unregister(temp_monitor_class);
+  class_destroy(temp_monitor_class);
+  unregister_chrdev(major_number, DEVICE_NAME);
+  printk(KERN_INFO "temp_monitor: Device removed\n");
 }
 
 module_init(temp_monitor_init);
 module_exit(temp_monitor_exit);
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Your Name");
-MODULE_DESCRIPTION("A CPU Temperature Monitoring Kernel Module");
+MODULE_AUTHOR("Uzair Hamed Mohammed");
+MODULE_DESCRIPTION(
+    "An Awesome and Super Complex CPU Temperature Monitoring Kernel Module");

Test/Mohammed_UzairHamed_HW6_main.c

@@ -1,24 +1,91 @@
-#include <stdio.h>
+/**************************************************************
+ * Class::  CSC-415-01 Fall 2024
+ * Name::  Uzair Hamed Mohammed
+ * Student ID::  920142896
+ * GitHub-Name::  gamersekofy
+ * Project:: Assignment 6 - Device Driver
+
+ *
+ * File:: Mohammed_UzairHamed_HW6_main.c
+ *
+ * Description::  This file contains a very easy to use and application that
+ reads and writes data
+ * to the tempMonitor kernel module.
+ **************************************************************/
+
 #include <fcntl.h>
-#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
 #include <sys/ioctl.h>
+#include <unistd.h>
 
 #define IOCTL_GET_TEMP _IOR('t', 1, int)
 
-int main() {
-    int fd, temp;
-    fd = open("/dev/temp_monitor", O_RDWR);
-    if (fd < 0) {
-        perror("Failed to open the device");
-        return -1;
+#define GREEN "\033[1;32m"
+#define RESET "\033[0m"
+
+void read_temp(int fd, const char *unit) {
+  char buffer[128];
+  ssize_t bytes_read;
+
+  /* Declare this variable because /sys/class/thermal/thermal_zonex/ isn't
+   available on virtual machines. In case of a virtual machine, set this flag
+   that will make the kernel module return a simulated temperature. */
+  int is_simulated = 0;
+
+  // Writing the desired unit or "simulate" command to the device
+  ssize_t bytes_written = write(fd, unit, strlen(unit));
+  if (bytes_written < 0) {
+    return;
+  }
+
+  // Reading the temperature
+  bytes_read = read(fd, buffer, sizeof(buffer));
+  if (bytes_read < 0) {
+    return;
+  } else {
+    buffer[bytes_read] = '\0';
+
+    // Check if the temperature is simulated. If it is, set flag here.
+    if (strstr(buffer, "(simulated temperature)") != NULL) {
+      is_simulated = 1;
     }
 
-    if (ioctl(fd, IOCTL_GET_TEMP, &temp) == -1) {
-        perror("Failed to get temperature");
-        close(fd);
-        return -1;
+    if (is_simulated) {
+      printf(GREEN "CPU Temperature\n--- -----------\n" RESET "%s\n", buffer);
+    } else {
+      printf(GREEN "CPU Temperature\n--- -----------\n" RESET "%s\n", buffer);
     }
-    printf("Current temperature: %d\n", temp);
-    close(fd);
-    return 0;
+  }
+}
+
+int main() {
+  int fd;
+  char choice;
+
+  // Access kernel module here
+  fd = open("/dev/temp_monitor", O_RDWR);
+  if (fd < 0) {
+    perror("Failed to open the device");
+    return -1;
+  }
+
+  // Ask the user for the preferred temperature unit
+  printf("Choose temperature unit (C/F): ");
+  scanf(" %c", &choice);
+
+  if (choice == 'C' || choice == 'c') {
+    // Request the kernel module provide temperature in Celsius
+    read_temp(fd, "C");
+  } else if (choice == 'F' || choice == 'f') {
+    // Request the kernel module provide the temperature in Fahrenheit
+    read_temp(fd, "F");
+  } else {
+    printf("Invalid choice. Please choose 'C' or 'F'.\n");
+    close(fd);
+    return -1;
+  }
+
+  close(fd);
+  return 0;
 }