Operating Systems - Prof. Omar Mansour

New York University

Tandon School of Engineering

Department of Computer Science and Engineering

Introduction to Operating Systems

Spring 2025

Assignment 6

(10 points)

1) (8 points) Repeat assignment 5B, except that you shall now use a TCP/IP socket for communicating between

the processes instead of a pipe.

Use the following socket functions in their default mode. You may use the man command in your Linux

virtual machine for information about the parameters:

CLIENT SERVER

socket() – opens a socket (similar to pipe() ) socket()

connect() – connects to a server bind() – assigns a particular port number to the server

listen() – listens to connection requests from clients

accept() – accepts a connection from client

read() – reads a buffer from the socket, just as in file

or pipe reading

write() – writes a buffer to the socket, just as in file or

pipe writing

close() – closes the socket close()

You shall use sockets of (domain, type, protocol) = (AF_INET , SOCK_STREAM, 0) and assign the parent

(consumer) as the server and the child (producer) as the client.

Insert an initial random wait (1 to 5 seconds) at the server process (but not the client) prior to it starting to

listen and accept connections.

The client may thus fail to connect if it tries to do so before the server has started to listen (which is after the

random wait). As such, you should insert a loop in the client that repeatedly attempts to connect, waiting 100

ms between attempts, till it succeeds, eventually.

2) 2 points): Answer the following for part 2:

a. Which of the calls above are blocking and which are not?

b. Is this a form of direct communications or indirect communications?

c. What is the failure flag returned from connect() that indicates the server is not ready?

d. How would you change your program to communicate between processes in different machines?

What to submit to gradescope:

Please submit the following files individually:

1) Source file(s) with appropriate comments.

Operating Systems - Prof. Omar Mansour

The naming should be similar to “lab#_$.c” (# is replaced with the assignment number and $ with the

question number within the assignment, e.g. lab4_b.c, for lab 4, question b OR lab5_1a for lab 5, question

1a).

2) A single pdf file (for images + report/answers to questions), named “lab#.pdf” (# is replaced by the

assignment number), containing:

• Screen shot(s) of your terminal window showing the current directory, the command used to

compile your program, the command used to run your program and the output of your program.

3) Your Makefile, if any. This is applicable only to kernel modules.

RULES:

• You shall use kernel version 4.x.x or above. You shall not use kernel version 3.x.x.

• You may consult with other students about GENERAL concepts or methods but copying code (or code

fragments) or algorithms is NOT ALLOWED and is considered cheating (whether copied form other

students, the internet or any other source).

• If you are having trouble, please ask your teaching assistant for help.

• You must submit your assignment prior to the deadline.