This page describes all filesystem operations we require a filesystem to support.

mount(dir, fs)

Mounts the filesystem at the path dir. Note that fs must be an instance of DefaultFS.

On error a string will be returned describing the error. On success 0 will be returned.

umount(dir)

Unmounts the filesystem mounted at the path dir. If no filesystem is mounted an error will be returned.

On error a string will be returned describing the error. On success 0 will be returned.

readdir(dir)

Reads the directory at dir. If dir is not a directory an error will be returned.

On error a string will be returned describing the error. On success a list of Dirents will be returned.

stat(path)

Get information about the file at path.

On error a string will be returned describing the error. On success a Stat will be returned.

unlink(path)

Removes the link at path.

On error a string will be returned describing the error. On success a Stat will be returned.

create(path, mode)

Create a regular file at path with permissions set to mode.

On error a string will be returned describing the error. On success a number will be returned.

truncate(path, size)

Extend or shrink the size of the file at path to size (in bytes). If size is bigger than the original filesize, the file will be extended by null bytes. If size is smaller than the original filesize, the file will be shrunk.

On error a string will be returned describing the error. On success a the number of bytes added or removed will be returned.

open(path, flags, mode)

Opens the file at path and returns a FileDescriptor with attributes specified by flags,.

• If O_RDONLY is set in flags, the returned FileDescriptor can be used for reading.
• If O_WRONLY is set in flags, the returned FileDescriptor can be used for writing.
• If O_APPEND is set in flags, the returned FileDescriptor’s offset will be set to the end of the file.
• If O_TRUNC is set in flags, and O_WRONLY is set, the file will first be truncated to a file of 0 before a `FileDescriptor is returned.
• If O_CREAT is set in flags, if path does not exist, it will be created with the mode set to mode.

The flag O_RDWR is a combination of both O_RDONLY and O_WRONLY.

On error a string will be returned describing the error. On success a FileDescriptor will be returned.

close(fd)

Closes fd, an instance of FileDescriptor and releases any associated resources.

chmod(path, mode)

Changes the mode of the file at path to mode.

mode must be an integer with the lower nine bits forming a permissions string.

On error a string will be returned describing the error. On success a 0 will be returned.

ioctl(fd, request, data)

Control the underlying “device”/interact with the filesystem on a “meta” level.

fd must be an instance of FileDescriptor describing a file to operate on.

request can be one of:

• IOCTL_IS_TTY - determine if the file is interactive
• IOCTL_SELECT_INODE - “select” the inode

You can define your own request numbers and can optionally use data to pass in arbitrary javascript objects as parameters.

The return values are controlled by the definition of request.

link(src_path, dst_path)

Make a hardlink at dst_path to the same file as src_path.

On error a string will be returned describing the error. On success a 0 will be returned.

mkdir(path)

Create a directory at path.

On error a string will be returned describing the error. On success a 0 will be returned.

write(fd, buffer)

Write into fd, an instance of FileDescriptor, from buffer.

buffer must be an instance of Uint8Array.

On error a string will be returned describing the error. On success the number of bytes written will be returned.

read(fd, buffer)

Read from fd, an instance of FileDescriptor, into buffer.

buffer must be an instance of Uint8Array.

On error a string will be returned describing the error. On success the number of bytes read will be returned.

seek(fd, offset, whence)

Change the offset of fd (an instance of FileDescriptor) by offset using the scheme whence.

Availible schemes:

• SEEK_SET - set the offset relative to the start of the file
• SEEK_END - set the offset relative to the end of the file
• SEEK_CURR - set the offset relative to the current offset of fd

On error a string will be returned describing the error. On success a 0 will be returned.