#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Biswa Kalyan Bhuyan");
MODULE_DESCRIPTION("Process explorer");
MODULE_VERSION("0.1");

// Find processes matching a name or PID
static int find_process(const char *name, unsigned int target_pid)
{
    struct task_struct *task;
    int process_count = 0;
    int hidden_count = 0;
    
    printk(KERN_INFO "Process Explorer: Enumerating all processes\n");
    
    // Loop through all processes in the system
    for_each_process(task) {
        process_count++;
        
        // If we're searching for a specific PID or name
        if (target_pid > 0 && task->pid == target_pid) {
            printk(KERN_INFO "Process Explorer: Found PID %d, Name: %s\n",
                   task->pid, task->comm);
            
            // Print parent process info
            if (task->parent) {
                printk(KERN_INFO "Process Explorer: Parent PID %d, Name: %s\n",
                       task->parent->pid, task->parent->comm);
            }
            
            // Print additional info
            printk(KERN_INFO "Process Explorer: User ID: %d, Group ID: %d\n",
                   task->cred->uid.val, task->cred->gid.val);
            
            hidden_count++;
        }
        else if (name && strncmp(task->comm, name, TASK_COMM_LEN) == 0) {
            printk(KERN_INFO "Process Explorer: Found PID %d with name %s\n",
                   task->pid, task->comm);
            hidden_count++;
        }
    }
    
    printk(KERN_INFO "Process Explorer: Total processes: %d\n", process_count);
    
    if (target_pid > 0 || name) {
        printk(KERN_INFO "Process Explorer: Found %d matching processes\n", hidden_count);
    }
    
    return 0;
}

// Module parameters
static unsigned int target_pid = 0;
module_param(target_pid, uint, 0644);
MODULE_PARM_DESC(target_pid, "Target process ID to search for");

static char *target_name = NULL;
module_param(target_name, charp, 0644);
MODULE_PARM_DESC(target_name, "Target process name to search for");

// Module initialization
static int __init proc_explorer_init(void)
{
    printk(KERN_INFO "Process Explorer: Module loaded\n");
    
    // Search for a specific process if provided
    if (target_pid > 0) {
        printk(KERN_INFO "Process Explorer: Searching for PID %u\n", target_pid);
    } else if (target_name) {
        printk(KERN_INFO "Process Explorer: Searching for processes named '%s'\n", target_name);
    } else {
        printk(KERN_INFO "Process Explorer: No search criteria provided. Use 'target_pid' or 'target_name' parameters.\n");
        return 0;
    }
    
    // Find and print process info
    find_process(target_name, target_pid);
    
    return 0;
}

// Module cleanup
static void __exit proc_explorer_exit(void)
{
    printk(KERN_INFO "Process Explorer: Module unloaded\n");
}

module_init(proc_explorer_init);
module_exit(proc_explorer_exit);