Fix media processing getting stuck on too much stdin/stderr (#16136)

* Fix media processing getting stuck on too much stdin/stderr

See thoughtbot/terrapin#5

* Remove dependency on paperclip-av-transcoder gem

* Remove dependency on streamio-ffmpeg gem

* Disable stdin on ffmpeg process

12 files changed, 234 insertions, 67 deletions

diff --git a/Gemfile b/Gemfile
index fb80e24d5c2..6ca0a81deb7 100644
--- a/Gemfile
+++ b/Gemfile
@@ -21,8 +21,6 @@ gem 'aws-sdk-s3', '~> 1.94', require: false
 gem 'fog-core', '<= 2.1.0'
 gem 'fog-openstack', '~> 0.3', require: false
 gem 'paperclip', '~> 6.0'
-gem 'paperclip-av-transcoder', '~> 0.6'
-gem 'streamio-ffmpeg', '~> 3.0'
 gem 'blurhash', '~> 0.1'
 
 gem 'active_model_serializers', '~> 0.10'
diff --git a/Gemfile.lock b/Gemfile.lock
index 3c36e07bc17..b1ae4fd226a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -77,8 +77,6 @@ GEM
     ast (2.4.2)
     attr_encrypted (3.1.0)
       encryptor (~> 3.0.0)
-    av (0.9.0)
-      cocaine (~> 0.5.3)
     awrence (1.1.1)
     aws-eventstream (1.1.1)
     aws-partitions (1.449.0)
@@ -156,8 +154,6 @@ GEM
     cld3 (3.4.2)
       ffi (>= 1.1.0, < 1.16.0)
     climate_control (0.2.0)
-    cocaine (0.5.8)
-      climate_control (>= 0.0.3, < 1.0)
     coderay (1.1.3)
     color_diff (0.1)
     concurrent-ruby (1.1.8)
@@ -402,9 +398,6 @@ GEM
       mime-types
       mimemagic (~> 0.3.0)
       terrapin (~> 0.6.0)
-    paperclip-av-transcoder (0.6.4)
-      av (~> 0.9.0)
-      paperclip (>= 2.5.2)
     parallel (1.20.1)
     parallel_tests (3.7.0)
       parallel
@@ -605,8 +598,6 @@ GEM
     stackprof (0.2.16)
     statsd-ruby (1.5.0)
     stoplight (2.2.1)
-    streamio-ffmpeg (3.0.2)
-      multi_json (~> 1.8)
     strong_migrations (0.7.6)
       activerecord (>= 5)
     temple (0.8.2)
@@ -750,7 +741,6 @@ DEPENDENCIES
   omniauth-saml (~> 1.10)
   ox (~> 2.14)
   paperclip (~> 6.0)
-  paperclip-av-transcoder (~> 0.6)
   parallel (~> 1.20)
   parallel_tests (~> 3.7)
   parslet
@@ -795,7 +785,6 @@ DEPENDENCIES
   sprockets-rails (~> 3.2)
   stackprof
   stoplight (~> 2.2.1)
-  streamio-ffmpeg (~> 3.0)
   strong_migrations (~> 0.7)
   thor (~> 1.1)
   tty-prompt (~> 0.23)
diff --git a/app/lib/video_metadata_extractor.rb b/app/lib/video_metadata_extractor.rb
new file mode 100644
index 00000000000..03e40f923e5
--- /dev/null
+++ b/app/lib/video_metadata_extractor.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+class VideoMetadataExtractor
+  attr_reader :duration, :bitrate, :video_codec, :audio_codec,
+              :colorspace, :width, :height, :frame_rate
+
+  def initialize(path)
+    @path     = path
+    @metadata = Oj.load(ffmpeg_command_output, mode: :strict, symbol_keys: true)
+
+    parse_metadata
+  rescue Terrapin::ExitStatusError, Oj::ParseError
+    @invalid = true
+  rescue Terrapin::CommandNotFoundError
+    raise Paperclip::Errors::CommandNotFoundError, 'Could not run the `ffprobe` command. Please install ffmpeg.'
+  end
+
+  def valid?
+    !@invalid
+  end
+
+  private
+
+  def ffmpeg_command_output
+    command = Terrapin::CommandLine.new('ffprobe', '-i :path -print_format :format -show_format -show_streams -show_error -loglevel :loglevel')
+    command.run(path: @path, format: 'json', loglevel: 'fatal')
+  end
+
+  def parse_metadata
+    if @metadata.key?(:format)
+      @duration = @metadata[:format][:duration].to_f
+      @bitrate  = @metadata[:format][:bit_rate].to_i
+    end
+
+    if @metadata.key?(:streams)
+      video_streams = @metadata[:streams].select { |stream| stream[:codec_type] == 'video' }
+      audio_streams = @metadata[:streams].select { |stream| stream[:codec_type] == 'audio' }
+
+      if (video_stream = video_streams.first)
+        @video_codec = video_stream[:codec_name]
+        @colorspace  = video_stream[:pix_fmt]
+        @width       = video_stream[:width]
+        @height      = video_stream[:height]
+        @frame_rate  = video_stream[:avg_frame_rate] == '0/0' ? nil : Rational(video_stream[:avg_frame_rate])
+      end
+
+      if (audio_stream = audio_streams.first)
+        @audio_codec = audio_stream[:codec_name]
+      end
+    end
+
+    @invalid = true if @metadata.key?(:error)
+  end
+end
diff --git a/app/models/media_attachment.rb b/app/models/media_attachment.rb
index 5cf4d812798..3515f689508 100644
--- a/app/models/media_attachment.rb
+++ b/app/models/media_attachment.rb
@@ -287,7 +287,7 @@ class MediaAttachment < ApplicationRecord
       if instance.file_content_type == 'image/gif'
         [:gif_transcoder, :blurhash_transcoder]
       elsif VIDEO_MIME_TYPES.include?(instance.file_content_type)
-        [:video_transcoder, :blurhash_transcoder, :type_corrector]
+        [:transcoder, :blurhash_transcoder, :type_corrector]
       elsif AUDIO_MIME_TYPES.include?(instance.file_content_type)
         [:image_extractor, :transcoder, :type_corrector]
       else
@@ -388,7 +388,7 @@ class MediaAttachment < ApplicationRecord
   # paths but ultimately the same file, so it makes sense to memoize the
   # result while disregarding the path
   def ffmpeg_data(path = nil)
-    @ffmpeg_data ||= FFMPEG::Movie.new(path)
+    @ffmpeg_data ||= VideoMetadataExtractor.new(path)
   end
 
   def enqueue_processing
diff --git a/config/application.rb b/config/application.rb
index 9aa1594ce5c..37a996224f7 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -13,12 +13,12 @@ require_relative '../lib/redis/namespace_extensions'
 require_relative '../lib/paperclip/url_generator_extensions'
 require_relative '../lib/paperclip/attachment_extensions'
 require_relative '../lib/paperclip/media_type_spoof_detector_extensions'
-require_relative '../lib/paperclip/transcoder_extensions'
 require_relative '../lib/paperclip/lazy_thumbnail'
 require_relative '../lib/paperclip/gif_transcoder'
-require_relative '../lib/paperclip/video_transcoder'
+require_relative '../lib/paperclip/transcoder'
 require_relative '../lib/paperclip/type_corrector'
 require_relative '../lib/paperclip/response_with_limit_adapter'
+require_relative '../lib/terrapin/multi_pipe_extensions'
 require_relative '../lib/mastodon/snowflake'
 require_relative '../lib/mastodon/version'
 require_relative '../lib/devise/two_factor_ldap_authenticatable'
diff --git a/lib/paperclip/attachment_extensions.rb b/lib/paperclip/attachment_extensions.rb
index e25a34213b3..271f8b60340 100644
--- a/lib/paperclip/attachment_extensions.rb
+++ b/lib/paperclip/attachment_extensions.rb
@@ -2,6 +2,10 @@
 
 module Paperclip
   module AttachmentExtensions
+    def meta
+      instance_read(:meta)
+    end
+
     # We overwrite this method to support delayed processing in
     # Sidekiq. Since we process the original file to reduce disk
     # usage, and we still want to generate thumbnails straight
diff --git a/lib/paperclip/gif_transcoder.rb b/lib/paperclip/gif_transcoder.rb
index 9f3c8e8be33..74aa1a0b261 100644
--- a/lib/paperclip/gif_transcoder.rb
+++ b/lib/paperclip/gif_transcoder.rb
@@ -100,7 +100,8 @@ end
 
 module Paperclip
   # This transcoder is only to be used for the MediaAttachment model
-  # to convert animated gifs to webm
+  # to convert animated GIFs to videos
+
   class GifTranscoder < Paperclip::Processor
     def make
       return File.open(@file.path) unless needs_convert?
diff --git a/lib/paperclip/image_extractor.rb b/lib/paperclip/image_extractor.rb
index aab675a060f..17fe4326fdb 100644
--- a/lib/paperclip/image_extractor.rb
+++ b/lib/paperclip/image_extractor.rb
@@ -31,21 +31,17 @@ module Paperclip
     private
 
     def extract_image_from_file!
-      ::Av.logger = Paperclip.logger
-
-      cli = ::Av.cli
       dst = Tempfile.new([File.basename(@file.path, '.*'), '.png'])
       dst.binmode
 
-      cli.add_source(@file.path)
-      cli.add_destination(dst.path)
-      cli.add_output_param loglevel: 'fatal'
-
       begin
-        cli.run
-      rescue Cocaine::ExitStatusError, ::Av::CommandError
+        command = Terrapin::CommandLine.new('ffmpeg', '-i :source -loglevel :loglevel -y :destination', logger: Paperclip.logger)
+        command.run(source: @file.path, destination: dst.path, loglevel: 'fatal')
+      rescue Terrapin::ExitStatusError
         dst.close(true)
         return nil
+      rescue Terrapin::CommandNotFoundError
+        raise Paperclip::Errors::CommandNotFoundError, 'Could not run the `ffmpeg` command. Please install ffmpeg.'
       end
 
       dst
diff --git a/lib/paperclip/transcoder.rb b/lib/paperclip/transcoder.rb
new file mode 100644
index 00000000000..e997040867d
--- /dev/null
+++ b/lib/paperclip/transcoder.rb
@@ -0,0 +1,102 @@
+# frozen_string_literal: true
+
+module Paperclip
+  # This transcoder is only to be used for the MediaAttachment model
+  # to check when uploaded videos are actually gifv's
+  class Transcoder < Paperclip::Processor
+    def initialize(file, options = {}, attachment = nil)
+      super
+
+      @current_format      = File.extname(@file.path)
+      @basename            = File.basename(@file.path, @current_format)
+      @format              = options[:format]
+      @time                = options[:time] || 3
+      @passthrough_options = options[:passthrough_options]
+      @convert_options     = options[:convert_options].dup
+    end
+
+    def make
+      metadata = VideoMetadataExtractor.new(@file.path)
+
+      unless metadata.valid?
+        log("Unsupported file #{@file.path}")
+        return File.open(@file.path)
+      end
+
+      update_attachment_type(metadata)
+      update_options_from_metadata(metadata)
+
+      destination = Tempfile.new([@basename, @format ? ".#{@format}" : ''])
+      destination.binmode
+
+      @output_options = @convert_options[:output]&.dup || {}
+      @input_options  = @convert_options[:input]&.dup  || {}
+
+      case @format.to_s
+      when /jpg$/, /jpeg$/, /png$/, /gif$/
+        @input_options['ss'] = @time
+
+        @output_options['f']       = 'image2'
+        @output_options['vframes'] = 1
+      when 'mp4'
+        @output_options['acodec'] = 'aac'
+        @output_options['strict'] = 'experimental'
+      end
+
+      command_arguments, interpolations = prepare_command(destination)
+
+      begin
+        command = Terrapin::CommandLine.new('ffmpeg', command_arguments.join(' '), logger: Paperclip.logger)
+        command.run(interpolations)
+      rescue Terrapin::ExitStatusError => e
+        raise Paperclip::Error, "Error while transcoding #{@basename}: #{e}"
+      rescue Terrapin::CommandNotFoundError
+        raise Paperclip::Errors::CommandNotFoundError, 'Could not run the `ffmpeg` command. Please install ffmpeg.'
+      end
+
+      destination
+    end
+
+    private
+
+    def prepare_command(destination)
+      command_arguments  = ['-nostdin']
+      interpolations     = {}
+      interpolation_keys = 0
+
+      @input_options.each_pair do |key, value|
+        interpolation_key = interpolation_keys
+        command_arguments << "-#{key} :#{interpolation_key}"
+        interpolations[interpolation_key] = value
+        interpolation_keys += 1
+      end
+
+      command_arguments << '-i :source'
+      interpolations[:source] = @file.path
+
+      @output_options.each_pair do |key, value|
+        interpolation_key = interpolation_keys
+        command_arguments << "-#{key} :#{interpolation_key}"
+        interpolations[interpolation_key] = value
+        interpolation_keys += 1
+      end
+
+      command_arguments << '-y :destination'
+      interpolations[:destination] = destination.path
+
+      [command_arguments, interpolations]
+    end
+
+    def update_options_from_metadata(metadata)
+      return unless @passthrough_options && @passthrough_options[:video_codecs].include?(metadata.video_codec) && @passthrough_options[:audio_codecs].include?(metadata.audio_codec) && @passthrough_options[:colorspaces].include?(metadata.colorspace)
+
+      @format          = @passthrough_options[:options][:format] || @format
+      @time            = @passthrough_options[:options][:time]   || @time
+      @convert_options = @passthrough_options[:options][:convert_options].dup
+    end
+
+    def update_attachment_type(metadata)
+      @attachment.instance.type = MediaAttachment.types[:gifv] unless metadata.audio_codec
+    end
+  end
+end
diff --git a/lib/paperclip/transcoder_extensions.rb b/lib/paperclip/transcoder_extensions.rb
deleted file mode 100644
index c0b2447f3ea..00000000000
--- a/lib/paperclip/transcoder_extensions.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-# frozen_string_literal: true
-
-module Paperclip
-  module TranscoderExtensions
-    # Prevent the transcoder from modifying our meta hash
-    def initialize(file, options = {}, attachment = nil)
-      meta_value = attachment&.instance_read(:meta)
-      super
-      attachment&.instance_write(:meta, meta_value)
-    end
-  end
-end
-
-Paperclip::Transcoder.prepend(Paperclip::TranscoderExtensions)
diff --git a/lib/paperclip/video_transcoder.rb b/lib/paperclip/video_transcoder.rb
deleted file mode 100644
index 4d9544231e3..00000000000
--- a/lib/paperclip/video_transcoder.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-# frozen_string_literal: true
-
-module Paperclip
-  # This transcoder is only to be used for the MediaAttachment model
-  # to check when uploaded videos are actually gifv's
-  class VideoTranscoder < Paperclip::Processor
-    def make
-      movie = FFMPEG::Movie.new(@file.path)
-
-      attachment.instance.type = MediaAttachment.types[:gifv] unless movie.audio_codec
-
-      Paperclip::Transcoder.make(file, actual_options(movie), attachment)
-    end
-
-    private
-
-    def actual_options(movie)
-      opts = options[:passthrough_options]
-      if opts && opts[:video_codecs].include?(movie.video_codec) && opts[:audio_codecs].include?(movie.audio_codec) && opts[:colorspaces].include?(movie.colorspace)
-        opts[:options]
-      else
-        options
-      end
-    end
-  end
-end
diff --git a/lib/terrapin/multi_pipe_extensions.rb b/lib/terrapin/multi_pipe_extensions.rb
new file mode 100644
index 00000000000..51d7de37c59
--- /dev/null
+++ b/lib/terrapin/multi_pipe_extensions.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: false
+# Fix adapted from https://github.com/thoughtbot/terrapin/pull/5
+
+module Terrapin
+  module MultiPipeExtensions
+    def read
+      read_streams(@stdout_in, @stderr_in)
+    end
+
+    def close_read
+      begin
+        @stdout_in.close
+      rescue IOError
+        # Do nothing
+      end
+
+      begin
+        @stderr_in.close
+      rescue IOError
+        # Do nothing
+      end
+    end
+
+    def read_streams(output, error)
+      @stdout_output = ''
+      @stderr_output = ''
+
+      read_fds = [output, error]
+
+      until read_fds.empty?
+        to_read, = IO.select(read_fds)
+
+        if to_read.include?(output)
+          @stdout_output << read_stream(output)
+          read_fds.delete(output) if output.closed?
+        end
+
+        if to_read.include?(error)
+          @stderr_output << read_stream(error)
+          read_fds.delete(error) if error.closed?
+        end
+      end
+    end
+
+    def read_stream(io)
+      result = ''
+
+      begin
+        while (partial_result = io.read_nonblock(8192))
+          result << partial_result
+        end
+      rescue EOFError, Errno::EPIPE
+        io.close
+      rescue Errno::EINTR, Errno::EWOULDBLOCK, Errno::EAGAIN
+        # Do nothing
+      end
+
+      result
+    end
+  end
+end
+
+Terrapin::CommandLine::MultiPipe.prepend(Terrapin::MultiPipeExtensions)