CSE312- Midterm Exam Project Solved

In this project, you will design and implement a simplifies UNIX like file system in C or C++. This project does not use MIPS or SPIM, so it is completely independent of your other homework assignments. This will count as midterm exam for this course. Part 1

Design a file system that uses i-nodes blocks and data blocks to keep your files. Your file system will use, a i-node structure like Fig 4.33 of your textbook (single link, double link and triple link i-nodes). Your directory, i-node block, data block structure will be similar to Fig 4.34 of the textbook.  Your file attributes will include size, last modification date and time, and name of the file. No permissions or owner attributes will be kept. Write a design report that specifies the following 

•        Define your directory structure and directory entries;

•        Define how you keep the free blocks and free i-nodes;

•        Define your i-node structure

•        Define your superblock that contains crucial information about the file system such as the block size, i-node positions, block positions, etc.

Your report should include the function names of your source code that handles the file system operations listed in the table of Part 3.

Part 2
Write a C/C++ program that creates an empty file system as a 1 MB Linux file. This file will include all the information about your file system including the i-nodes, data blocks, free blocks and i-nodes, directories, data, etc. The sample run of the program will be like

makeFileSystem 4 400 mySystem.dat

where 4 is the block size of the file system in KB for both data blocks and i-node blocks, and 400 is the number of free i-nodes for an empty file system. mySystem.dat is the Linux file that contains all the file system. When you

work on the file system, this file contains all the information for the file system. Note that the size of mySystem.dat will be exactly 1 MB all the time whether it contains any information or not. Part 3

You will write a program that performs file system operation on the file system. The program will work like following

fileSystemOper fileSystem.data operation parameters

where fileSystemOper is your program, fileSystem.data is the file system data file that you have created in Part 2. You will keep modifying the same fileSystem.data file for all your operations. Allowable operations and parameters for these operations are given below in the following table. 

 

Operation
Parameters
Explanation
Example
list
Path
Lists the contents of the directory shown by path on the screen. 
fileSystemOper fileSystem.data list “/”

lists the contents of the root directory. The output will be like ls –l
mkdir rmdir
Path and dir name
Makes or removes a directory
fileSystemOper fileSystem.data mkdir

“/usr/ysa” makes a new directory under the directory “ysa” if possible. These two works exactly like mkdir and rmdir commands of Linux shell
dumpe2fs
None
Gives information about the file system.
fileSystemOper fileSystem.data dumpe2fs

works like simplified and modified Linux dumpe2fs command. It will list block count, i-node count, free block and i-nodes, number of files and directories, and block size. Different from regular dumpe2fs, this command lists all the occupied i-nodes, blocks and the file names for each of them.
write
Path and file name
Creates and writes data to the file 
fileSystemOper fileSystem.data write “/usr/ysa/file” linuxFile

Creates a file named file under “/usr/ysa” in your file system, then copies the contents of the Linux file into the new file. This works very similar to Linux copy command.
read
Path and file name
Reads data from the

file
fileSystemOper fileSystem.data read “/usr/ysa/file” linuxFile

Reads the file named file under “/usr/ysa” in your file system, then writes this data to the Linux file. This again works very similar to Linux copy command. 
del
Path and file name
Deletes file from the path
fileSystemOper fileSystem.data del “/usr/ysa/file”

Deletes the file named file under “/usr/ysa” in your file system. This again works very similar to Linux del command.
Operations below are bonus (20 points)
ln 
Source and destination path and file names
Hard linking between

2 files
fileSystemOper fileSystem.data ln “/usr/ysa/file1” “/usr/ysa/file2”

Allows more than one filename to refer to the same

file

Linux ln command
lnsym
Source and destination path and file names
Symbolic linking between 2 files
fileSystemOper fileSystem.data lnsym “/usr/ysa/file1” “/usr/ysa/file2”

Linux ln-s command
 

fsck
none
Simplified File system check
fileSystemOper fileSystem.data fsck

Just print the two table of Fig 4.27 of your textbook for both i-nodes and blocks  
Here is a sequence file system operation commands that you can use to test your file system. Suppose you have a file named linuxFile.data in your Linux current directory.

 

makeFileSystem 4 400 mySystem.data fileSystemOper fileSystem.data mkdir “/usr” fileSystemOper fileSystem.data mkdir “/usr/ysa” fileSystemOper fileSystem.data mkdir “/bin/ysa”                         ; Should print error! fileSystemOper fileSystem.data write “/usr/ysa/file1” linuxFile.data fileSystemOper fileSystem.data write “/usr/file2” linuxFile.data

fileSystemOper fileSystem.data write “/file3” linuxFile.data

fileSystemOper fileSystem.data list “/”                        ; Should list 1 dir, 1 file fileSystemOper fileSystem.data del “/usr/ysa/file1” fileSystemOper fileSystem.data dumpe2fs

fileSystemOper fileSystem.data read “/usr/file2” linuxFile2.data 

         cmp linuxFile2.data linuxFile.data                  ; Should not print any difference

fileSystemOper fileSystem.data ln “/usr/file2” “/usr/linkedfile2” fileSystemOper fileSystem.data list “/usr"

fileSystemOper fileSystem.data write “/usr/linkedfile2” linuxFile.data fileSystemOper fileSystem.data dumpe2fs

fileSystemOper fileSystem.data lnsym “/usr/file2” “/usr/symlinkedfile2” fileSystemOper fileSystem.data list “/usr" fileSystemOper fileSystem.data del “/usr/file2” fileSystemOper fileSystem.data list “/usr" ; Should see likedfile2 is there, symlinkedFile2 is there but..  fileSystemOper fileSystem.data write “/usr/symlinkedfile2” linuxFile.data ;  Should print error!

fileSystemOper fileSystem.data dumpe2fs

 

 

 Notes
 

1.     Always be careful about the errors, such as bad block sizes, bad file names, non-existent files or directories, etc.

2.     Run experiments that uses up all of your i-nodes and data blocks.  

3.     Try to get fragmentation and show your fragmented file system using the dumpe2fs command.

4.     Do not use any code from any other source even a single line!