This is an implementation for a software disk system.

gcc -g -o filesystem.out testfile.c filesystem.c softwaredisk.c

Inode Layout

• 2 bytes Mode
• 2 bytes file size in blocks
• 13 2 byte direct pointers
• 1 2 byte direct pointer

Directory Entry Layout:

• 2 bytes block number/pointer to inode 0 go until 511
• 2 bytes size of file name
• 507 bytes for file name
• 1 byte null terminator

set_bitmap(unsigned long bitmap_type, int index)

• Marks the bit at index in the bitmap_type as free

unset_bitmap(unsigned long bitmap_type, int index)

• Marks the bit at index in the bitmap_type as used

get_free_index(unsigned long bitmap_type)

• Returns the first free index of Inode or Data Block indicated by bitmap

update_directory_entry_block(unsigned long index, Directory_Entry_Block *buff)

• updates/writes the directory_entry_block at index index

update_inode_block(unsigned long index, Inode_Block *buff)

• updates/writes the inode_block at index index.

get_directory_entry_block(unsigned long index, Directory_Entry_Block *buff)

• eturns an Directory_Entry_Block given an index

get_inode_block(int index, Inode_Block *buff)

• Returns an Inode_Block given an index

hard_delete(uint16_t index)

• sets all the data in a datablock block to 0s

check_structure_alignment()

• Checks if the filesystem has been initialized correctly.

fs_print_error(void)

• prints any FSERROR

open_file(char *name, FileMode mode)

• facilitates opening a file

create_file(char *name)

• facilitates createion of a new file

read_file(File file, void *buf, unsigned long numbytes)

• facilitates reading of a file

write_file(File file, void *buf, unsigned long numbytes)

• facilitates writing to files

close_file(File file)

• closes a file

file_exists(char *name)

• checks to see if a particular file is stored on the disk

file_length(File file)

• returns the size of a file

delete_file(char *name)

• finds and delets a file using hard_delete()

seek_file(File file, unsigned long bytepos)

• sets the file's current possission

• Filenames:

  Files are limited to 507 characters (not including the null terminal)

• Files:
  A max of 512 files