Operating Systems Project Assignment: A Portable File System using Contiguous Allocation Method for GCP VM

Objective:

1. Practical experience with the problems of file systems.

2. Experience with the Windows or Unix/Linux operating system.

3. Keep the definition simple. Don't read things into the problem that aren't there.

These will be individual projects. For Project 2 you will use any operating system under Google Cloud Platform (GCP) VM. You may write the program in any language that is supported under any Integrated Development Environment (IDE) that runs on your selected OS on VM. Keep in mind that more help may be available to you in some languages than in others. Furthermore, available controls, etc. may make some of these tasks easier in one language than in another.

Problem Statement:

Implement a Portable File System (PFS) with Contiguous Allocation Method, which can perform "Allocate a file", and "Move files from the Windows file system into your file." You should have your own directory structure, allocation table, etc. inside your file.

Move files back out of your file to the Windows file system or Linux/Unix file system. When your program is running it should somehow accept the following commands:

open   PFSfile                  Allocate a new 10 KByte "PFS" file if it does not already exist. If it does exist, begin using it for further commands.
put     myfile                   Copy the Windows (or Unix/Linux) file "myfile" into your PFS file.
get     myfile                   Extract file "myfile" from your PFS file and copy it to the current Windows (or Unix/Linux) directory.
rm      myfile                   Delete "myfile" from your PFS file.
dir                                 List the files in your PFS file.
putr    myfile "Remarks"   Append remarks to the directory entry for myfile in your PFS file.
kill       PFSfile                 Delete the PFSfile from the Windows file system.
quit                               Exit PFS.

You can provide those commands through command line interface ONLY (No GUI will be accepted).

Limits:

1. PFS is NOT a memory based file system, but based on the existing file system on your OS, such as Windows or Linux/Unix.

2. Command-Line Interface (CLI) Only, i.e., cmd.exe (in Windows) or shell interface (in Unix/Linux). When PFS is executed, it will show the prompt as:

C:\> pfs.exe PFS> open pfs

3. Filenames are a maximum of 20 bytes. And, file extension is optional like Unix/Linux.

4. The directory need handle only Name, Size, Time and Date. For example,

PFS> dir

5. If the original PFS file fills up then you should create a new PFS "volume" with the same name but a different suffix - e.g., pfs.1, pfs.2, etc., each the same size as the first "volume".

6. Your file system should use Contiguous Allocation for an allocation scheme where "disk block" size is 256 bytes.

7. In your files system, each file has one File Control Block (FCB) that includes file name, file size, create time, create date, starting block ID, ending block ID and more (if needed).

8. Your file system should consist of two main parts, i) Directory Structure and ii) Data Blocks. Therefore, you need to define the directory data structure that includes File Control Block (FCB) for each file.

9. In addition, your files system should be able to manage free blocks. You can use any techniques that you learned in the classroom, such as bit map (vector) or linked free space management. Free block management should be part of directory structure.

10. You should handle unusual conditions such as trying to put a file into the PFS when a file with that name is already there, file too large to fit into one "volume", etc.

If you need to make assumptions, do so. Make a "reasonable" choice & include it in the write-up. Reasonable means that you can explain the logic behind your choice. These problems change each semester and it is difficult to imagine every question that might come up. When in doubt, ask to Professor Lee or the GA.

Write-up

You should submit a write-up as well as your program. Your write-up should include any known bugs, limitations, and assumptions in your program. This write-up should be in text-format and titled as 'README'. It should be submitted along with your code. GA will use the 'README' file to compile (or install) and run your program. If the GA has trouble with your program then he will contact you to makeup it.