Not able to use sudo command in System calls using non root user

I have to run my process as a non root user.
This process needs to call for some system calls.

Example system("udhcpc -ieth0")

The above example works well when my process started with root user

If I changed my process start with non root user. This system calls fails because it needs root permission to start.

So I gave sudo in the system call. But it fails.
I have also tried to use execl instead of system call. But I am seeing the same issue

The following error occurs
"sudo: unable to change to root gid: Operation not permitted"
"sudo: unable to initialize policy plugin"

Welcome.

sudo needs to be configured for each specific combination of command + account. So to run udhcpc from the account 'foobar' append the following to /etc/sudoers using the program visudo

%foobar ALL=(root:root) /sbin/udhcpc -i eth0

Or

%foobar ALL=(root:root) NOPASSWD:/sbin/udhcpc -i eth0

Mind the spacing in either case and be sure to use the correct path for udhcpc.

For background see Michael W Lucas' talk "sudo: You're Doing It Wrong", which has a video and slides available. It is long but thorough.