CS 33211 Operating Systems
Project #3

Due via subversion by 11:59 on Tuesday, November 27th

IMPLEMENTING INDEXED FILE SYSTEM

Write a program that implements a rudimentary 2-level indexed file
system. Your program should create a file named DISK and simulate disk
operations on this file. The disk blocks are to be exactly 10
bytes. The disk has a single track (all blocks are stored
sequentially). The track size is 100 blocks.  In communication with
the disk you should use random access read and write functions.  


In Linux, check the corresponding man-pages for their operation.

    man -S 3p write

Specifically, you should consider operations pread()/pwrite() and
lseek().

In Windows, use fread()/frite()/fseek()

Also, use open()/close() functions for opening/closing the file

The only allowed block size that you can read from or write to the
disk is 10 bytes. Your filesystem is to have a single unnamed
file. Its i-node will be stored in the first block of the disk. The
i-node has two types of information. In the first byte - file size is
stored. The remaining bytes are used to store references (block
numbers) to the blocks where file data is stored. Use byte-size
integers to store block numbers. Notice that the i-node can store 9
references. The first 7 references are directly to the data
blocks. The 8-th reference is to the single indirect index block. This
index block should contain additional 10 references to data blocks.
The last 9-th reference is to the double indirect index block.  This
block contains references to the blocks that, in turn, contain
references to data blocks. If the block is not allocated it should
contain 0. Notice that a block can be partially filled and the program
should use the file size to determine where the file data ends.

Your program should be able to accept information from the standard
input and write it to the simulated file. Assume that all the
information is alphanumberic. The input is accepted until keyword
ENDFILE is entered. All the information should be written to the file
except the keyword ENDFILE. The program should gracefully handle files
that are too large to fit in the disk (print an error message and
quit).  After writing the file your program should read the file data
back and print it to the standard output. You are not allowed to store
the data in your program memory between writing to the disk and
reading it back.


Submitting Your Project and Grading


The programming project is worth 50 points. Late projects are
accepted. Late policies are outlined in the syllabus. The grading will
be such that the working program submitted a few days late will
receive a higher grade that the program that does not work but is
submitted. If your program still does not work, submit a text file
specifying how the program fails (does not compile, fails test
examples, etc.), what you think the reason is and how it can be
fixed. You may be given partial credit.