sguimmara / coolfs

A toy FUSE filesystem

coolfs

A toy FUSE filesystem.

Getting started

You will need autotool to generate the Makefiles.

To compile, you need libfuse installed. On debian-based distributions:

sudo apt install -y libfuse-dev

Then compile with make:

./configure
make

Execute tests with:

make check

Design

FUSE layer (fs.h)

The FUSE implementation.

int _mkdir(struct inode *parent, const char *name);
int _read(struct inode *inode, char *buf, size_t size, off_t offset);
int _getattr(struct inode* inode, struct stat *st);

Path parser (path.h)

Parses paths, split them into fragments, etc.

struct Path {
    size_t fragments;
    char **fragbuf;
};

int parse(const char* path, struct Path *result);
char *dirname(const struct Path *path);
char *filename(const struct Path *path);

Encryption layer (crypt.h)

Use AES (provided by OpenSSL) to encrypt and decrypt file content. The initialization vector is randomly generated at inode creation and stored in the inode itself.

#define IV_SIZE 16

/**
 * Generates a random initialization vector.
 */
int create_iv(char *dst);

/**
 * Encrypts the buffer in place. Note: the buffer size must be a
 * multiple of the AES block size (16 byte).
 */ 
int encrypt(const char *iv, const char* key, char *buf, size_t bufsize);

/**
 * Decrypts the buffer in place. Note: the buffer size must be a
 * multiple of the AES block size (16 byte).
 */ 
int decrypt(const char *iv, const char *key, char *buf, size_t bufsize);

Persistence layer (storage.h)

int write_blocks(
    blno_t *blocks,
    size_t count,
    const char *buf,
    size_t bufsize);

int read_blocks(
    blno_t *blocks,
    size_t count,
    const char *buf,
    size_t bufsize);