File System Exercise 3 Solution

This exercise follows on from Tutorial Exercise 8. If you wait until the deadline to do this exercise it is unlikely that you will be able to finish the assignment 4.
You may work in pairs for this exercise, with your A4 partner, since some code will potentially be common with the assignment. MarkUs will only create the appropriate directory in your repository when you log into MarkUs and either create your group, or declare that you will work alone. The groups will get a new shared repository, and the students working solo may also get a new repository. Please log into MarkUs well before the deadline to take these steps. (If you create the directory in your repo yourself, then MarkUs won't know about it and we won't be able to see your work.)
It is your responsibility to log into MarkUs before the exercise deadline to ensure that you know where to commit your work, and so that MarkUs can connect your work to the grading system.
Requirements
Your final task in this series of exercises is to print the directory block contents. While you are doing this, you should work out how the directory structure creates a linked list of directory entries by using rec_len to show where the next directory entry begins. Note that rec_len in the last directory entry takes you to the end of the block.
When printing the blocks, first print the root directory. Then for each inode that is in use, check if it is a directory. If it is a directory, print the contents of the directory block.  You do not need to print anything for file blocks.
For emptydisk.img your output should exactly match the following. In other words, we should be able to use diff to compare your output to this and see that it is identical (the indentation below uses 4 spaces).
Inodes: 32
Blocks: 128
Block group:
    block bitmap: 3
    inode bitmap: 4
    inode table: 5
    free blocks: 105
    free inodes: 21
    used_dirs: 2
Block bitmap: 11111111 11111111 11111100 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000001 
Inode bitmap: 11111111 11100000 00000000 00000000 

Inodes:
[2] type: d size: 1024 links: 3 blocks: 2
[2] Blocks:  9

Directory Blocks:
   DIR BLOCK NUM: 9 (for inode 2)
Inode: 2 rec_len: 12 name_len: 1 type= d name=.
Inode: 2 rec_len: 12 name_len: 2 type= d name=..
Inode: 11 rec_len: 1000 name_len: 10 type= d name=lost+found
Note: The original twolevel.img was a bit confusing, so we uploaded a multilevel.img to the images directory and changed the output below.
For multilevel.img your output should match the following:
Inodes: 32
Blocks: 128
Block group:
    block bitmap: 3
    inode bitmap: 4
    inode table: 5
    free blocks: 102
    free inodes: 17
    used_dirs: 4
Block bitmap: 11111111 11111111 11111111 00000000 10000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000001 
Inode bitmap: 11111111 11111110 00000000 00000000 

Inodes:
[2] type: d size: 1024 links: 4 blocks: 2
[2] Blocks:  9
[12] type: d size: 1024 links: 3 blocks: 2
[12] Blocks:  23
[13] type: d size: 1024 links: 2 blocks: 2
[13] Blocks:  24
[14] type: f size: 0 links: 1 blocks: 0
[14] Blocks: 
[15] type: f size: 39 links: 1 blocks: 2
[15] Blocks:  33

Directory Blocks:
   DIR BLOCK NUM: 9 (for inode 2)
Inode: 2 rec_len: 12 name_len: 1 type= d name=.
Inode: 2 rec_len: 12 name_len: 2 type= d name=..
Inode: 11 rec_len: 20 name_len: 10 type= d name=lost+found
Inode: 12 rec_len: 36 name_len: 6 type= d name=level1
Inode: 15 rec_len: 944 name_len: 5 type= f name=afile
   DIR BLOCK NUM: 23 (for inode 12)
Inode: 12 rec_len: 12 name_len: 1 type= d name=.
Inode: 2 rec_len: 12 name_len: 2 type= d name=..
Inode: 13 rec_len: 1000 name_len: 6 type= d name=level2
   DIR BLOCK NUM: 24 (for inode 13)
Inode: 13 rec_len: 12 name_len: 1 type= d name=.
Inode: 12 rec_len: 12 name_len: 2 type= d name=..
Inode: 14 rec_len: 1000 name_len: 5 type= f name=bfile
Submission
Ensure that you have a repository directory created by MarkUs for this exercise (fs3), then add and commit readimage.c and ext2.h to this directory.