cs45p1c

SELF
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/module.h>

asmlinkage int sys_printself(void)
{
  struct task_struct *task;

  printk(KERN_INFO "My Process id: %d\n", current->pid);
  printk(KERN_INFO "My Name: %s\n", current->comm);
  printk(KERN_INFO "My parent processes until init :\n");
  for(task = current; task != &init_task; task = task->parent)
  {
    printk(KERN_INFO "Name: %s (PID: %d)\n",task->comm , task->pid);
  }

  return 0;
}

OTHER

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

asmlinkage int sys_printother(int pid)
{
  struct task_struct *task;
  struct task_struct *temp_task;

  task = pid_task(find_vpid(pid), PIDTYPE_PID);

  if (task == NULL)
    printk(KERN_INFO "No process with PID %d\n", pid);
  else
  {
    printk(KERN_INFO "PID %d Name: %s\n", pid, task->comm);
    printk(KERN_INFO "PID %d parent processes until init :\n", pid);
    for(temp_task = task; temp_task != &init_task; temp_task = temp_task->parent)
    {
      printk(KERN_INFO "Name: %s (PID: %d)\n",temp_task->comm , temp_task->pid);
    }
  }

  return 0;
}

TEST
#include <linux/unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <stdio.h>

#define __NR_helloworld 337
#define __NR_printself  338
#define __NR_printother 339

int main(int argc, char *argv[]) {
        syscall(__NR_helloworld);
        syscall(__NR_printself);

        int pidInput;
        printf("PID: ");
        scanf("%d", &pidInput);


        syscall(__NR_printother, pidInput);
        return 0;
}