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

7 files changed, 176 insertions, 50 deletions

diff --git a/lib/paperclip/attachment_extensions.rb b/lib/paperclip/attachment_extensions.rb
index e25a34213..271f8b603 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 9f3c8e8be..74aa1a0b2 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 aab675a06..17fe4326f 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 000000000..e99704086
--- /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 c0b2447f3..000000000
--- 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 4d9544231..000000000
--- 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 000000000..51d7de37c
--- /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)