1. The File System & Directory System Module Presented By: Erhan Atilla Avinal Maitreya Natu Shivkundan Singh Tej Tam H. Vu

2. Overview The project focuses on: The project focuses on: Logical and abstract view of files and directories to the users by hiding the physical details. Logical and abstract view of files and directories to the users by hiding the physical details. Efficient use of underlying storage device Efficient use of underlying storage device Provide exhaustive tools for organization of files and directories Provide exhaustive tools for organization of files and directories Provide protection features to the files and directories Provide protection features to the files and directories

3. Interface to File and Directory system I/O System Interface readDescriptor(), writeDescriptor(), readDataBlock(), writeDataBlock() Device Organization Methods readBlock() writeBlock() BLOCK I/O Subsystem File & Directory Operations File & Directory System File System Interface Symbolic File NameOpen File objects Raw disk blocks Bitmap, Descriptors, Data blocks Files and Directories

4. Levels of abstraction of the Physical Disk /(root) Dir1Dir2File1 File 2 File 3 Physical Disk Logical view of disk as 1D blocks BitmapDescriptorsData blocks Tree containing files and directories

5. The Class Design Disk BitSet Bitmap, DESCRIPTOR[ ] Descriptor_Array, byte[ ][ ]Block_Array readDescriptor, writeDescriptor, readBlock, writeBlock, findFreeBlock, findFreeDescriptor DESCRIPTOR int Type, int Size, int Block Addresses[] FileDirectory FileSystem DirectorySystem FileDirectorySystem String Name DESCRIPTOR Descriptor, int Children Directory Parent Directory Location int Protection, int Owner int Use String NameDESCRIPTOR Descriptor int CurrentPosition Directory Location int Protectionint Owner int Use createDirectory deleteDirectory changeDirectorymoveDirectory changeProtectionlistDirectory createFile openFile readFile writeFile renameFile rewindFile changeProtection Disk d, FileSystem fileSys, DirectorySystem dirSys UserInterface Run()

6. DIRECTORY SYSTEM FILE & DIRECTORY SYSTEM DIRECTORY createFile, deleteFile, openFile, readFile, writeFile, openFile, rewindFile, changeProtection createDirectory, deleteDirectory, changeDirectory, moveDirectory, listDirectory, changeProtection addFile, removeFile, changeProtection readDescriptor, writeDescriptor, readBlock, writeBlock FILE SYSTEM FILE DISK DESCRIPTOR Communication between classes USER INTERFACE

7. Features of our file system File Operations File Operations Create, Delete, Rename, Read, Write, Copy, Rewind, Change Protection. Create, Delete, Rename, Read, Write, Copy, Rewind, Change Protection. Directory Operations Directory Operations Create, Delete, Move, Change Directory, List, Change Protection Create, Delete, Move, Change Directory, List, Change Protection Supports an inverted tree directory structure. Supports an inverted tree directory structure. Provides facility to create directories within directory. Provides facility to create directories within directory. Provides protection to files and directories Provides protection to files and directories Protection bits for every file and directory Protection bits for every file and directory Owner information is stored with every file and directory Owner information is stored with every file and directory User friendly interface User friendly interface Provides an interface for using all the file system features with an online help to use the commands. Provides an interface for using all the file system features with an online help to use the commands. Adaptive to different disk configurations Adaptive to different disk configurations Simple modifications can make the subsystem work for disk with different capacity, block size and number of files and directories. Simple modifications can make the subsystem work for disk with different capacity, block size and number of files and directories.

8. Features contd.. Specifications: Specifications: Disk block size: 512Bytes Disk block size: 512Bytes Maximum file size: 6656 Bytes Maximum file size: 6656 Bytes Maximum number of files and directories: 160 Maximum number of files and directories: 160 Protection bits: r-w-x bits are associated with each file and directory Protection bits: r-w-x bits are associated with each file and directory

9. Functioning of the system 200:0200:0 ……………….. ……………………………….. FDS DIRECTORY & DSFILE & FS DISK /(root) dir1 createDirectory findFreeDescriptor 200:0200:0 writeDescriptor addDirectory writeDescriptor 211:0211:0 findFreeBlock Name Des Own Pro Dir1 1 4 7 writeBlock User Interface file1 createDirectory createfile FindFreeDescriptorwriteDescriptor 100:0100:0 addFile Name Des Own Pro Dir1 1 4 7 File1 2 4 7 writeBlockwriteDescriptor 221:0221:0 command

10. Limitations & Further Extensions Provides a small upper limit on file and directory size (of 6656 bytes). Provides a small upper limit on file and directory size (of 6656 bytes). The limit can be increased by using multilevel indexing in the descriptor The limit can be increased by using multilevel indexing in the descriptor Provides same access rights to all users Provides same access rights to all users Can be extended by adding more bytes for storing protection information Can be extended by adding more bytes for storing protection information Does not support symbolic links Does not support symbolic links This feature can be extended by adding some link information in the directory & the descriptor structure This feature can be extended by adding some link information in the directory & the descriptor structure

11. Thank you