wasmex
v0.8.3

Wasmex.Pipe (wasmex v0.8.3)

A Pipe is a memory buffer that can be used in exchange for a Wasm file.

Pipes have a read and write position which can be set using seek/2.

example

 Example

Pipes can be written to and read from:

iex> {:ok, pipe} = Wasmex.Pipe.new()
iex> Wasmex.Pipe.write(pipe, "hello")
{:ok, 5}
iex> Wasmex.Pipe.seek(pipe, 0)
iex> Wasmex.Pipe.read(pipe)
"hello"

They can be used to capture stdout/stdin/stderr of WASI programs:

iex> {:ok, stdin} = Wasmex.Pipe.new()
iex> {:ok, stdout} = Wasmex.Pipe.new()
iex> {:ok, stderr} = Wasmex.Pipe.new()
iex> Wasmex.Store.new_wasi(%Wasmex.Wasi.WasiOptions{
...>   stdin: stdin,
...>   stdout: stdout,
...>   stderr: stderr,
...> })

Link to this section Summary

Types

t()

Functions

new()

Creates and returns a new Pipe.

read(pipe)

Reads all available bytes from the Pipe and returns them as a binary.

seek(pipe, pos_from_start)

Sets the read/write position of the Pipe to the given position.

size(pipe)

Returns the current size of the Pipe in bytes.

write(pipe, binary)

Writes the given binary into the pipe.

Link to this section Types

Link to this type

t()

@type t() :: %Wasmex.Pipe{reference: reference(), resource: binary()}

Link to this section Functions

Link to this function

new()

@spec new() :: {:error, reason :: binary()} | {:ok, t()}

Creates and returns a new Pipe.

example

 Example 

iex> {:ok, %Pipe{}} = Wasmex.Pipe.new()
Link to this function

read(pipe)

@spec read(t()) :: binary()

Reads all available bytes from the Pipe and returns them as a binary.

This function does not block if there are no bytes available. Reading starts at the current read position, see seek/2, and forwards the read position to the end of the Pipe. The read bytes are not erased and can be read again after seeking back.

example

 Example 

iex> {:ok, pipe} = Wasmex.Pipe.new()
iex> Wasmex.Pipe.write(pipe, "hello")
iex> Wasmex.Pipe.read(pipe) # current position is at EOL, nothing more to read
""
iex> Wasmex.Pipe.seek(pipe, 0)
iex> Wasmex.Pipe.read(pipe)
"hello"
iex> Wasmex.Pipe.seek(pipe, 3)
iex> Wasmex.Pipe.read(pipe)
"lo"
iex> Wasmex.Pipe.read(pipe)
""
Link to this function

seek(pipe, pos_from_start)

@spec seek(t(), integer()) :: :ok | :error

Sets the read/write position of the Pipe to the given position.

The position is given as a number of bytes from the start of the Pipe.

example

 Example 

iex> {:ok, pipe} = Wasmex.Pipe.new()
iex> Wasmex.Pipe.write(pipe, "hello")
iex> Wasmex.Pipe.seek(pipe, 0)
:ok
iex> Wasmex.Pipe.read(pipe)
"hello"
Link to this function

size(pipe)

@spec size(t()) :: integer()

Returns the current size of the Pipe in bytes.

example

 Example 

iex> {:ok, pipe} = Wasmex.Pipe.new()
iex> Wasmex.Pipe.size(pipe)
0
iex> Wasmex.Pipe.write(pipe, "hello")
iex> Wasmex.Pipe.size(pipe)
5
Link to this function

write(pipe, binary)

@spec write(t(), binary()) :: {:ok, integer()} | :error

Writes the given binary into the pipe.

Writing starts at the current write position, see seek/2, and forwards it.

example

 Example 

iex> {:ok, pipe} = Wasmex.Pipe.new()
iex> Wasmex.Pipe.write(pipe, "hello")
{:ok, 5}
iex> Wasmex.Pipe.seek(pipe, 0)
iex> Wasmex.Pipe.read(pipe)
"hello"