F3.IO.FileSystem behaviour (F3 v0.1.0)

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Operating-system calls used by F3.IO.Local.

Production code uses F3.IO.FileSystem.OS. Tests pass a Mox double as :file_system on F3.IO.Local.open/2 so read and close failures can be returned without changing a real file.

A double returns the same tagged tuples as File and :file:

defmodule StubFiles do
  @behaviour F3.IO.FileSystem

  @impl true
  def stat(_path), do: {:ok, %File.Stat{type: :regular, size: 2}}

  @impl true
  def open(_path, _modes), do: {:ok, :fd}

  @impl true
  def pread(_fd, _offset, length), do: {:ok, String.duplicate("a", length)}

  @impl true
  def close(_fd), do: :ok
end

Summary

Callbacks

close(term)

Closes a descriptor. :ok is success. {:error, reason} is an OS error.

open(t, list)

Opens path with modes. The modes used by F3.IO.Local are [:read, :raw, :binary].

pread(term, non_neg_integer, non_neg_integer)

Reads length bytes at offset from an open descriptor. :eof means the position is past the file.

stat(t)

File metadata for path. A missing path is {:error, :enoent}.

Callbacks

close(term)

@callback close(term()) :: :ok | {:error, atom()}

Closes a descriptor. :ok is success. {:error, reason} is an OS error.

open(t, list)

@callback open(Path.t(), [atom()]) :: {:ok, term()} | {:error, atom()}

Opens path with modes. The modes used by F3.IO.Local are [:read, :raw, :binary].

pread(term, non_neg_integer, non_neg_integer)

@callback pread(term(), non_neg_integer(), non_neg_integer()) ::
  {:ok, binary()} | :eof | {:error, atom()}

Reads length bytes at offset from an open descriptor. :eof means the position is past the file.

stat(t)

@callback stat(Path.t()) :: {:ok, File.Stat.t()} | {:error, atom()}

File metadata for path. A missing path is {:error, :enoent}.