Fix for Errno::ENAMETOOLONG in Thumbnails

* Uses Paperclip's Tempfile instead of Ruby's in Thumbnail
* Also includes a test for TempfileFactory to be sure it does not revert to similar behavior
* In the tests, give the OS some wiggle room in the Tempfile name to ensure the error does not occur before we are ready for it. The wiggle room is needed because the randomized part of the name has a variable number of characters.

lib/paperclip/thumbnail.rb

@@ -63,8 +63,8 @@ module Paperclip
     # that contains the new image.
     def make
       src = @file
-      dst = Tempfile.new([@basename, @format ? ".#{@format}" : ''])
-      dst.binmode
+      filename = [@basename, @format ? ".#{@format}" : ""].join
+      dst = TempfileFactory.new.generate(filename)
 
       begin
         parameters = []

spec/paperclip/tempfile_factory_spec.rb

@@ -26,4 +26,8 @@ describe Paperclip::TempfileFactory do
    file = subject.generate
    assert File.exist?(file.path)
   end
+
+  it "does not throw Errno::ENAMETOOLONG when it has a really long name" do
+    expect { subject.generate("o" * 255) }.to_not raise_error
+  end
 end

spec/paperclip/thumbnail_spec.rb

@@ -481,4 +481,20 @@ describe Paperclip::Thumbnail do
       end
     end
   end
+
+  context "with a really long file name" do
+    before do
+      tempfile = Tempfile.new("f")
+      tempfile_additional_chars = tempfile.path.split("/")[-1].length + 15
+      image_file = File.new(fixture_file("5k.png"), "rb")
+      @file = Tempfile.new("f" * (255 - tempfile_additional_chars))
+      @file.write(image_file.read)
+      @file.rewind
+    end
+
+    it "does not throw Errno::ENAMETOOLONG" do
+      thumb = Paperclip::Thumbnail.new(@file, geometry: "50x50", format: :gif)
+      expect { thumb.make }.to_not raise_error
+    end
+  end
 end