Introduction
In this assignment we will explore file I/O and how to implement a basic device driver inside a Loadable Kernel Module (LKM). First, you will write a user-space C program that takes commands from the user to read, write and seek on a file. You will use this program to test the functionality of a custom device driver that you'll create in Part B.
Part A - User-Space Test Program
Write an interactive test program that will allow you to read from, write to and seek in a file. Your program should accept the name of the file on the command line:
./pa2test filename
If the filename doesn't exist, or isn't readable/writeable, your program should print an error message, and terminate with a non-zero exit status.
Once successfully invoked, your interactive program should open filename for reading/writing, prompt the user with the string Option (r for read, w for write, s for seek): and then accept the following input, followed each time by the carriage return/enter key:
r - Your test program should immediately ask for the number of bytes to read using the prompt:
Enter the number of bytes you want to read:
Making sure you create a large enough buffer using malloc(), read the file starting from it's current position. Then, print the returned data out to the console (stdout), followed by a newline (" ").
w - Your program should ask for the data to be written to the file, using the prompt:
Enter the string you want to write:
https://canvas.colorado.edu/courses/74858/assignments/1089929?module_item_id=2973991 1/2
9/25/21, 4:42 PM PA2 - Part A
The user then enters the desired data terminated by a carriage return. Your program should then write this data to the file.
s - Your program should prompt for values for offset and whence:
Enter an offset value:
Enter a value for whence (0 for SEEK_SET, 1 for SEEK_CUR, 2 for SEEK_END):
Your program should then set it's position in the file according to the offset and whence. See the lseek manpage (https://man7.org/linux/man-pages/man2/lseek.2.html) for more info.
control+d - Terminate the program, and return the success exit status.
Other - If the user enters something other than listed above, ignore it and prompt the user again.
We've included a precompiled pa2test for you to use as an example. Download it from here, and then chmod +x ~/Downloads/pa2test to make it executable.
Submission
You are required to submit the following to Canvas:
pa2test.c
https://canvas.colorado.edu/courses/74858/assignments/1089929?module_item_id=2973991 2/2
