Need to build a simple shell in C without using C built-in system calls

The code will include process execution, piping and forks and I will provide a simple base code however, I want to add additional features to it like supporting a foreground process and single background process simultaneously. The ability to support for I/O redirection (stdin, stdout, stderr) and piping between two programs and the ability of catching and handling signals. The code I have will demonstrates the basic concept of a shell program. Pretty much any standard library or system call can be used apart from system(3) function which is essentially a wrapper for a shell and is off limits. Speaking more broadly, any library function or system call that is effectively a wrapper for another shell shouldn't be used.