Validates whether an image is acceptable through mime type

image/jpeg, image/png & image/gif are considered the allowed mime types
for an image. mimemagic gem is added as dependency in order to do the
checking.

Added tests to check against three supported mime types. A fake jpg
fixture (created with 'touch' command) has been added to test that
extension is no longer used.

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/axlsx/drawing/pic.rb b/lib/axlsx/drawing/pic.rb
index 571e9047..b090c661 100644
--- a/lib/axlsx/drawing/pic.rb
+++ b/lib/axlsx/drawing/pic.rb
@@ -25,8 +25,8 @@ module Axlsx
       @picture_locking = PictureLocking.new(options)
     end
 
-    # allowed file extenstions
-    ALLOWED_EXTENSIONS = ['gif', 'jpeg', 'png', 'jpg']
+    # allowed mime types
+    ALLOWED_MIME_TYPES = %w(image/jpeg image/png image/gif)
 
     # The name to use for this picture
     # @return [String]
@@ -67,7 +67,7 @@ module Axlsx
 
     def image_src=(v)
       Axlsx::validate_string(v)
-      RestrictionValidator.validate 'Pic.image_src', ALLOWED_EXTENSIONS, File.extname(v.downcase).delete('.')
+      RestrictionValidator.validate 'Pic.image_src', ALLOWED_MIME_TYPES, MimeMagic.by_magic(File.open(v)).to_s
       raise ArgumentError, "File does not exist" unless File.exist?(v)
       @image_src = v
     end