Fix #5065: .webp images upload support

Add ability to upload .webp images.

Animated WebP images aren't supported. This is because they aren't
supported by FFmpeg yet[1], so generating thumbnails and samples for
them would be more complicated than for other formats.

[1]: https://trac.ffmpeg.org/ticket/4907

app/logical/exif_tool.rb

@@ -48,7 +48,7 @@ class ExifTool
     end
 
     def is_animated?
-      frame_count.to_i > 1 || is_animated_avif?
+      frame_count.to_i > 1 || is_animated_webp? || is_animated_avif?
     end
 
     def is_animated_gif?
@@ -59,6 +59,10 @@ class ExifTool
       file_ext == :png && is_animated?
     end
 
+    def is_animated_webp?
+      file_ext == :webp && metadata["RIFF:Duration"].present?
+    end
+
     def is_animated_avif?
       file_ext == :avif && metadata["QuickTime:CompatibleBrands"].to_a.include?("avis")
     end
@@ -123,8 +127,10 @@ class ExifTool
     def loop_count
       return Float::INFINITY if metadata["GIF:AnimationIterations"] == "Infinite"
       return Float::INFINITY if metadata["PNG:AnimationPlays"] == "inf"
+      return Float::INFINITY if metadata["RIFF:AnimationLoopCount"] == "inf"
       return metadata["GIF:AnimationIterations"] if has_key?("GIF:AnimationIterations")
       return metadata["PNG:AnimationPlays"] if has_key?("PNG:AnimationPlays")
+      return metadata["RIFF:AnimationLoopCount"] if has_key?("RIFF:AnimationLoopCount")
 
       # If the AnimationIterations tag isn't present, then it's counted as a loop count of 0.
       return 0 if is_animated_gif? && !has_key?("GIF:AnimationIterations")
@@ -153,6 +159,8 @@ class ExifTool
         :avif
       elsif has_key?("QuickTime:MovieHeaderVersion")
         :mp4
+      elsif keys.grep(/\ARIFF:/).any?
+        :webp
       elsif has_key?("Matroska:DocType")
         :webm
       elsif has_key?("Flash:FlashVersion")

app/logical/media_file.rb

@@ -26,7 +26,7 @@ class MediaFile
     file = Kernel.open(file, "r", binmode: true) unless file.respond_to?(:read)
 
     case file_ext(file)
-    when :jpg, :gif, :png, :avif
+    when :jpg, :gif, :png, :webp, :avif
       MediaFile::Image.new(file, **options)
     when :swf
       MediaFile::Flash.new(file, **options)
@@ -62,6 +62,10 @@ class MediaFile
     when /\A\x1a\x45\xdf\xa3/n
       :webm
 
+    # https://developers.google.com/speed/webp/docs/riff_container
+    when /\ARIFF....WEBP/
+      :webp
+
     # https://www.ftyps.com
     # isom (common) - MP4 Base Media v1 [IS0 14496-12:2003]
     # mp42 (common) - MP4 v2 [ISO 14496-14]
@@ -144,7 +148,7 @@ class MediaFile
 
   # @return [Boolean] true if the file is an image
   def is_image?
-    file_ext.in?([:jpg, :png, :gif, :avif])
+    file_ext.in?(%i[jpg png gif webp avif])
   end
 
   # @return [Boolean] true if the file is a video

app/logical/media_file/image.rb

@@ -16,6 +16,8 @@ class MediaFile::Image < MediaFile
     when :avif
       # XXX Mirrored AVIFs should be unsupported too, but we currently can't detect the mirrored flag using exiftool or ffprobe.
       !metadata.is_rotated? && !metadata.is_cropped? && !metadata.is_grid_image? && !metadata.is_animated_avif?
+    when :webp
+      !is_animated?
     else
       true
     end
@@ -34,11 +36,12 @@ class MediaFile::Image < MediaFile
   end
 
   def frame_count
-    if file_ext == :gif
-      image.get("n-pages")
-    elsif file_ext == :png
+    case file_ext
+    when :gif, :webp
+      image.get("n-pages") if image.get_fields.include?("n-pages")
+    when :png
       metadata.fetch("PNG:AnimationFrames", 1)
-    elsif file_ext == :avif
+    when :avif
       video.frame_count
     else
       nil
@@ -124,6 +127,10 @@ class MediaFile::Image < MediaFile
     file_ext == :png && is_animated?
   end
 
+  def is_animated_webp?
+    file_ext == :webp && is_animated?
+  end
+
   def is_animated_avif?
     file_ext == :avif && is_animated?
   end

app/models/media_asset.rb

@@ -3,7 +3,7 @@
 class MediaAsset < ApplicationRecord
   class Error < StandardError; end
 
-  FILE_TYPES = %w[jpg png gif avif mp4 webm swf zip]
+  FILE_TYPES = %w[jpg png gif webp avif mp4 webm swf zip]
   FILE_KEY_LENGTH = 9
   VARIANTS = %i[preview 180x180 360x360 720x720 sample original]
   MAX_FILE_SIZE = Danbooru.config.max_file_size.to_i
@@ -372,7 +372,7 @@ class MediaAsset < ApplicationRecord
 
   concerning :FileTypeMethods do
     def is_image?
-      file_ext.in?(%w[jpg png gif avif])
+      file_ext.in?(%w[jpg png gif webp avif])
     end
 
     def is_static_image?

app/models/post.rb

@@ -188,7 +188,7 @@ class Post < ApplicationRecord
     end
 
     def is_image?
-      file_ext =~ /jpg|gif|png|avif/i
+      file_ext =~ /jpg|gif|png|webp|avif/i
     end
 
     def is_flash?