CODING IN C PLEASE!

See the startup program diskblocks.c in ~veerasam/linux7/a5

We learned about the # of storage blocks and overhead blocks required to store files using this inode structore diagram as the guidance. Now, challenge yourself and develop an algorithm and implement it to compute # of storage blocks and overhead blocks required to store a file of any size. Using this inode structore diagram as the guidance. Input will be specified in KBs. Output will have 2 numbers: # of storage blocks and # of overhead blocks.

Here are a sample run (to store a file of size 100KB, we need 13 blocks for storage and 1 overhead block). Note that the input is specified as a command line argument.

diskblocks 100

13 1

It is a good idea to use long instead of int, as shown in my startup program. When the input file size is too large to accommodate in the filesystem, output -1 for overhead blocks.

NOT USING: struct ext4_inode

^because my file does not run with it.

Startup File (to copy and paste):

#include

#include

#include

#include

#include

#include

#include

#define SIBLOCKS 2048L

#define DIBLOCKS (2048L*2048L)

#define TIBLOCKS (2048L*2048L*2048L)

long computeOverheadBlocks(long diskblocks) {

//CODE HERE!

return 0;

}

int main(int argc, char *argv[]) {

if (argc != 2) {

printf("Usage: diskblocks ");

return -1;

}

long filesize = atol(argv[1]);

long diskblocks = filesize / 8;

if (filesize % 8)

diskblocks++;

printf("%ld %d ", diskblocks, computeOverheadBlocks(diskblocks));

}

UNIX INODE STRUCTURE Legenda: - each (unix) file system has its own inode table; on disk each cylinder group will hold a relevant part of that table - each inode is referenced by a "device + inode number" pair - each file is assigned an inode number which is unique within that file system; each directory structure will consist of a list of "filename + inode number" pairs; inodes won't hold filenames - reserved inode numbers: 0,1,2 0 : deleted files/directories 1: (fs dependent) file system creation time/bad blocks count/..... 2: refers to the root directory of the file system - the "mode" field will always be the first field in the inode; the order of the other fields is file system dependent - timestamps: in seconds since 00:00:00 GMT 01-01-1970 - access time: updated after each read/write of file - modification time: updated after each write to file - inode change time: updated after each modification of one of the fields in the inode (chmod, chown, chgrp, ln, ) - triple indirect pointer: use is fs and max.file size dependent - status/flags like "compress file" or "do not update access time" or "do not extend file" are file system dependent - extra fields may hold: an inode generation number (for NFS) and/or ACL info (sometimes this field contains a "continuation inode number": a pointer to a special inode that holds ACL info) and/or a file type identification (for device files: major and minor per pointer number; for directories: inode number of parent directory); to reference up to 96KB all extra/reserved fields are file system dependent