From 2f2c73eebb80197c08964426c2beb54f842473d2 Mon Sep 17 00:00:00 2001
From: evazion <noizave@gmail.com>
Date: Mon, 31 Oct 2022 03:23:02 -0500
Subject: [PATCH] media assets: fix dimensions of corrupt GIFs.

Fix certain corrupt GIFs returning dimensions of 0x0. This happened
when the GIF was too corrupt for libvips to read. Fixed by using
ExifTool to read the dimensions instead.

Also add validations to ensure that it's not possible to have media
assets with a width or height of 0.
---
 app/logical/exif_tool.rb        | 8 ++++++++
 app/logical/media_file/image.rb | 2 ++
 app/models/media_asset.rb       | 3 +++
 test/unit/media_file_test.rb    | 2 ++
 4 files changed, 15 insertions(+)

diff --git a/app/logical/exif_tool.rb b/app/logical/exif_tool.rb
index 115aac03d..5933798b4 100644
--- a/app/logical/exif_tool.rb
+++ b/app/logical/exif_tool.rb
@@ -120,6 +120,14 @@ class ExifTool
         metadata.has_key?("PNG:Dream")
     end
 
+    def width
+      metadata.find { |name, value| name.match?(/\A(File|PNG|GIF|RIFF|Flash|Track\d+):ImageWidth\z/) }&.second
+    end
+
+    def height
+      metadata.find { |name, value| name.match?(/\A(File|PNG|GIF|RIFF|Flash|Track\d+):ImageHeight\z/) }&.second
+    end
+
     # @see http://www.vurdalakov.net/misc/gif/netscape-looping-application-extension
     # @see https://wiki.mozilla.org/APNG_Specification#.60acTL.60:_The_Animation_Control_Chunk
     # @see https://danbooru.donmai.us/posts?tags=-exif:GIF:AnimationIterations=Infinite+animated_gif
diff --git a/app/logical/media_file/image.rb b/app/logical/media_file/image.rb
index 175d44deb..0eee1bea5 100644
--- a/app/logical/media_file/image.rb
+++ b/app/logical/media_file/image.rb
@@ -10,6 +10,8 @@ class MediaFile::Image < MediaFile
   def dimensions
     image.size
   rescue Vips::Error
+    [metadata.width, metadata.height]
+  rescue
     [0, 0]
   end
 
diff --git a/app/models/media_asset.rb b/app/models/media_asset.rb
index 94a3c26eb..58ef91212 100644
--- a/app/models/media_asset.rb
+++ b/app/models/media_asset.rb
@@ -45,6 +45,9 @@ class MediaAsset < ApplicationRecord
   validates :md5, uniqueness: { conditions: -> { where(status: [:processing, :active]) } }, if: :md5_changed?
   validates :file_ext, inclusion: { in: FILE_TYPES, message: "File is not an image or video" }
   validates :file_key, length: { is: FILE_KEY_LENGTH }, uniqueness: true, if: :file_key_changed?
+  validates :file_size, comparison: { greater_than: 0 }, if: :file_size_changed?
+  validates :image_width, comparison: { greater_than: 0 }, if: :image_width_changed?
+  validates :image_height, comparison: { greater_than: 0 }, if: :image_height_changed?
 
   before_create :initialize_file_key
 
diff --git a/test/unit/media_file_test.rb b/test/unit/media_file_test.rb
index fd0f9e324..105100d0a 100644
--- a/test/unit/media_file_test.rb
+++ b/test/unit/media_file_test.rb
@@ -467,6 +467,7 @@ class MediaFileTest < ActiveSupport::TestCase
       @metadata = @file.metadata
 
       assert_equal(true, @file.is_corrupt?)
+      assert_equal([475, 600], @file.dimensions)
       assert_equal("File format error", @metadata["ExifTool:Error"])
       assert_equal("89a", @metadata["GIF:GIFVersion"])
       assert_equal(9, @metadata.count)
@@ -478,6 +479,7 @@ class MediaFileTest < ActiveSupport::TestCase
 
       assert_equal(true, @file.is_corrupt?)
       assert_equal(nil, @file.frame_count)
+      assert_equal([575, 800], @file.dimensions)
       assert_equal("File format error", @metadata["ExifTool:Error"])
       assert_equal("89a", @metadata["GIF:GIFVersion"])
       assert_equal(9, @metadata.count)