fsd: the thox filesystem daemon

The filesystem on thox is managed by fsd.

Todo

This daemon occupies a special place as loading other binaries cannot take place without this one. How is this managed?

fsd RPC bindings

The RPC calls provided by fsd are the following:

os.rpc.fs.open(path, mode)

Open a file descriptor on the given path. The mode can be one of the following:

“r”

Open the file for reading.

“w”

Open the file for writing. Deletes the destination file if it already existed. Copy on write is used.

In all cases, bytes will be returned; no byte transformation will be performed. Use iconv: character encoding conversions if you want to transpose from the file’s encoding to another.

The function returns the following:

  • If the request has succeeded, true followed by the numerical file descriptor to be used in subsequent calls.

  • If the request has failed, false followed by an error message.

Parameters

  • path (string) – Path of the file to open.

  • mode (string) – Opening mode.

Returns

The file context.

Return type

number

File descriptor calls

These calls happen on the file context provided by os.rpc.fs.open().

os.rpc.fs.file.read(count)

Read count bytes from the file descriptor represented by its numerical identifier fd. The function returns the bytes as a Lua string.

Parameters

count (number) – Number of requested bytes.

Returns

Up to count bytes.

Return type

string

os.rpc.fs.file.write(bytes)

Write the given bytes to the given file descriptor.

Parameters

bytes (string) – The bytes to write.

Returns

The number of written bytes.

Return type

number

os.rpc.fs.file.sync()

Synchronize the file’s in-core state with the storage device (what others call “flushing” for write handles).

os.rpc.fs.file.seek(whence, offset)

Seek to a position.

Parameters

  • whence (string) – “set”, “cur” or “end”.

  • offset (number) – The offset.

Returns

The new position.

Return type

number