akkoma/lib/pleroma/helpers/media_helper.ex

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# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Helpers.MediaHelper do
@moduledoc """
Handles common media-related operations.
"""
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@tmp_base "/tmp/pleroma-media_preview-pipe"
def image_resize(url, options) do
with executable when is_binary(executable) <- System.find_executable("convert"),
{:ok, args} <- prepare_resize_args(options),
url = Pleroma.Web.MediaProxy.url(url),
{:ok, env} <- Pleroma.HTTP.get(url),
{:ok, fifo_path} <- mkfifo()
do
run_fifo(fifo_path, env, executable, args)
else
nil -> {:error, {:convert, :command_not_found}}
{:error, _} = error -> error
end
end
defp prepare_resize_args(%{max_width: max_width, max_height: max_height} = options) do
quality = options[:quality] || 85
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resize = Enum.join([max_width, "x", max_height, ">"])
args = [
"-auto-orient", # Support for EXIF rotation
"-resize", resize,
"-quality", to_string(quality)
]
{:ok, args}
end
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defp prepare_resize_args(_), do: {:error, :missing_options}
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defp run_fifo(fifo_path, env, executable, args) do
args = List.flatten([fifo_path, args, "jpg:fd:1"])
pid = Port.open({:spawn_executable, executable}, [:use_stdio, :stream, :exit_status, :binary, args: args])
fifo = Port.open(to_charlist(fifo_path), [:eof, :binary, :stream, :out])
true = Port.command(fifo, env.body)
:erlang.port_close(fifo)
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loop_recv(pid)
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after
File.rm(fifo_path)
end
defp mkfifo() do
path = "#{@tmp_base}#{to_charlist(:erlang.phash2(self()))}"
case System.cmd("mkfifo", [path]) do
{_, 0} ->
spawn(fifo_guard(path))
{:ok, path}
{_, err} ->
{:error, {:fifo_failed, err}}
end
end
defp fifo_guard(path) do
pid = self()
fn() ->
ref = Process.monitor(pid)
receive do
{:DOWN, ^ref, :process, ^pid, _} ->
File.rm(path)
end
end
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end
defp loop_recv(pid) do
loop_recv(pid, <<>>)
end
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defp loop_recv(pid, acc) do
receive do
{^pid, {:data, data}} ->
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loop_recv(pid, acc <> data)
{^pid, {:exit_status, 0}} ->
{:ok, acc}
{^pid, {:exit_status, status}} ->
{:error, status}
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after
5000 ->
:erlang.port_close(pid)
{:error, :timeout}
end
end
end