Truncate long filename before saving tempfile on cache!

Reinstates patch by @vrinek that got rejected on upgrade to v0.10
Avoids Errno::ENAMETOOLONG exception that mostly occurs when saving
a remote image with greek letters in the URL

lib/carrierwave/uploader/download.rb

@@ -10,6 +10,10 @@ module Download
       include CarrierWave::Uploader::Cache
 
       class RemoteFile
+        # 255 characters is the max size of a filename in modern filesystems
+        # and 100 characters are allocated for versions
+        MAX_FILENAME_LENGTH = 255 - 100
+
         def initialize(uri)
           @uri = uri
         end
@@ -20,6 +24,23 @@ def original_filename
           unless File.extname(filename).present? || mime_type.blank?
             filename = "#{filename}.#{mime_type.extensions.first}"
           end
+
+          if filename.size > MAX_FILENAME_LENGTH
+            # 32 for MD5 and 2 for the __ separator
+            split_position = MAX_FILENAME_LENGTH - 32 - 2
+            extension = File.extname(filename) if File.extname(filename).present?
+
+            if extension
+              split_position -= extension.size
+              filename = File.basename(filename, extension)
+            end
+
+            hex = Digest::MD5.hexdigest(filename[split_position, filename.size])
+
+            filename = filename[0, split_position] + '__' + hex
+            filename << extension if extension
+          end
+
           filename
         end
 

spec/uploader/download_spec.rb

@@ -12,9 +12,19 @@
   end
 
   describe '#download!' do
+    let(:long_filename) { 'TgFCbMcysSV0v3-JJyvP02lfjh-XzbRxjsNpECoDJEsnoUUro9me195pWTE597xl6p6vDjo5sn5bGMjS40MRwMIsAsbNpqKfqdO19xvFbyPrVeXrkUMDeF_YjMUPXeVkRGdE3nGkK2zgwBCMAMMu2aU06Vod1FvslJaoasIFwqqF_jzolk2ot8nXlwTFvXt82CAV-a6gwqXFFdIfwRlCSF3gLGlfuPqSPzPxamwyDhzcJaf-eSMrsLE1-YA4BUZmEwD9hDKWusnpQ4jqGEbPBP5BKkM-HWPmxkVzkcQahtvQnlA' }
+    let(:long_url_without_extension) { 'http://www.example.com/' + long_filename }
+    let(:long_url) { long_url_without_extension + '.jpg' }
+
     before do
       allow(CarrierWave).to receive(:generate_cache_id).and_return('1369894322-345-1234-2255')
 
+      stub_request(:get, "www.example.com/" + long_filename + ".jpg").
+        to_return(body: File.read(file_path('test.jpg')), headers: { "Content-Type" => 'image/jpg' })
+
+      stub_request(:get, "www.example.com/" + long_filename).
+        to_return(body: File.read(file_path('test.jpg')), headers: { "Content-Type" => 'image/jpg' })
+
       stub_request(:get, "www.example.com/test.jpg")
         .to_return(body: File.read(file_path("test.jpg")))
 
@@ -39,6 +49,35 @@
       expect(@uploader.file).to be_an_instance_of(CarrierWave::SanitizedFile)
     end
 
+    context "on a remote file with a long filename" do
+      context "when the remote filename has no extension" do
+        it "should only use part of the original filename" do
+          @uploader.download!(long_url_without_extension)
+          @uploader.filename.size.should <= 255
+          @uploader.filename.should =~ /^#{long_url.split("/").last[0,121]}__/
+
+          regexp = /#{@uploader.filename.split("__").first}/
+          long_url_without_extension.split("/").last.should =~ regexp
+        end
+      end
+
+      context "when the remote filename has a proper extension" do
+        it "should only use part of the original filename" do
+          @uploader.download!(long_url)
+          @uploader.filename.size.should <= 255
+          @uploader.filename.should =~ /^#{long_url.split("/").last[0,117]}__/
+
+          regexp = /#{@uploader.filename.split("__").first}/
+          long_url.split("/").last.should =~ regexp
+        end
+
+        it "should retain the extension" do
+          @uploader.download!(long_url)
+          @uploader.filename.should =~ /\.jpg$/
+        end
+      end
+    end
+
     it "should be cached" do
       @uploader.download!('http://www.example.com/test.jpg')
       expect(@uploader).to be_cached