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; this comes from the fact that Lua strings are bytes before all.

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 response arguments.

Return type

table

os.rpc.fs.close(fd)

Close the given file descriptor. The function returns the following:

  • If the request has succeeded, true.

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

Parameters

fd (number) – File descriptor to close.

Returns

The response arguments.

Return type

table

os.rpc.fs.read(fd, count)

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

Parameters

  • fd (number) – File descriptor to use.

  • count (number) – Number of requested bytes.

Returns

Up to count bytes.

Return type

string

os.rpc.fs.write(fd, bytes)

Write the given bytes to the given file descriptor.

Parameters

  • fd (number) – File descriptor to use.

  • bytes (string) – The bytes to write.

Returns

The number of written bytes.

Return type

number

os.rpc.fs.sync(fd)

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

Parameters

fd (number) – File descriptor to use.

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

Seek to a position.

Parameters

  • fd (number) – File descriptor to use.

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

  • offset (number) – The offset.

  • mode (string) – Opening mode.

Returns

The new position.

Return type

number

Returns

The response arguments.

Return type

table

os.rpc.fs.close(fd)

Close the given file descriptor. The function returns the following:

  • If the request has succeeded, true.

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

Parameters

fd (number) – File descriptor to close.

Returns

The response arguments.

Return type

table

os.rpc.fs.read(fd, count)

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

Parameters

  • fd (number) – File descriptor to use.

  • count (number) – Number of requested bytes.

Returns

Up to count bytes.

Return type

string

os.rpc.fs.write(fd, bytes)

Write the given bytes to the given file descriptor.

Parameters

  • fd (number) – File descriptor to use.

  • bytes (string) – The bytes to write.

Returns

The number of written bytes.

Return type

number

os.rpc.fs.sync(fd)

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

Parameters

fd (number) – File descriptor to use.

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

Seek to a position.

Parameters

  • fd (number) – File descriptor to use.

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

  • offset (number) – The offset.

Returns

The new position.

Return type

number