Lab05 Fun with Processes and Pipes

Deliverables due Mon Mar 24 by 11:59pm in your lab04 GitHub repo

• A copy of xv6 with your new implementations of rdir, rpipe2, and rpipe3.
• Your implemenation should pass all of the Lab05 Autograder tests.
• Your source code should conform to xv6 formatting conventions.
• Your Project01 repo should not have any extraneous files or build artifacts
• Make sure to test your repo by cloning from GitHub to a different location and run the Autograder. This will catch problems like missing files.

Contents

1. Overview
2. rdir
3. rpipe2
4. rpipe3

Overview

In class we have been learning about file descriptors, processes, and pipes. These lab problems will give you more experience in working with the system calls for file descriptors, processes, and pipes.

hello

Add hello.c to your xv6. This will be used in the tests.

#include "kernel/types.h"
#include "kernel/fcntl.h"
#include "user/user.h"

int
main(int argc, char *argv[])
{
  printf("Hello, World!\n");
}

rdir - File Redirection

Usage:

rdir <input_filename> <command> <output_filename>

The rdir command will fork() and exec() the <commnand>. In addition it will redirect the stdin of the <command> to come from <input_filename> and redirect the stdout of the <command> to the <output_filename>. You will need to open <input_filename> for reading and you will need to create <output_filename> and open for writing. The rdir command should only fork one process. The parent should wait() for the child to exit.

Here is an example:

$ rdir README wc wc.out
$ cat wc.out
49 325 2305

rpipe2 - Pipe Redirection with Two Commands

Usage:

rpipe2 <command1> <command2>

The rpipe2 command will fork() two processes. In the first process it will exec() <command1> and in the second process it will exec() <command2>. In addition, rpipe2 will create a pipe and redirect the output of <command1> to the input of <command2>. The parent should wait for both children to exit.

Here is an example:

$ rpipe2 ls wc
29 116 726

The output of ls is redirected to the input of wc via a pipe.

rpipe3 - Pipe Redirection with Three Commands

Usage:

rpipe3 <command1> <command2> <command3>

The rpipe3 command is like rpipe2 except it will create three processes instead of two. The output of the first process running <command1> will be piped to the input of the second process running <command2>. The output of the second process will pipe its output to the input of the third process running <command3>. You will need to create three processes and two pipes. The parent should wait for all three processes to exit.

Here is an example:

$ rpipe3 ls wc cat
29 116 726

And another:

$ rpipe3 hello wc cat
1 2 14