[Ruby] Fix Content-Transfer-Encoding binary unpacking (#19132)

modules/openapi-generator/src/main/resources/ruby-client/api_client_faraday_partial.mustache

@@ -117,16 +117,22 @@
       request.options.on_data = Proc.new do |chunk, overall_received_bytes|
         stream << chunk
       end
+
       stream
     end
 
     def deserialize_file(response, stream)
       body     = response.body
-      if @config.return_binary_data == true
-        # return byte stream
       encoding = body.encoding
-        stream.join.force_encoding(encoding)
+
-      else
+      # reconstruct content
+      content = stream.join
+      content = content.unpack('m').join if response.headers['Content-Transfer-Encoding'] == 'binary'
+      content = content.force_encoding(encoding)
+
+      # return byte stream
+      return content if @config.return_binary_data == true
+
       # return file instead of binary data
       content_disposition = response.headers['Content-Disposition']
       if content_disposition && content_disposition =~ /filename=/i
@@ -136,17 +142,17 @@
         prefix = 'download-'
       end
       prefix = prefix + '-' unless prefix.end_with?('-')
-        encoding = body.encoding
+
       tempfile = Tempfile.open(prefix, @config.temp_folder_path, encoding: encoding)
-        tempfile.write(stream.join.force_encoding(encoding))
+      tempfile.write(content)
       tempfile.close
+
       config.logger.info "Temp file written to #{tempfile.path}, please copy the file to a proper folder "\
                           "with e.g. `FileUtils.cp(tempfile.path, '/new/file/path')` otherwise the temp file "\
                           "will be deleted automatically with GC. It's also recommended to delete the temp file "\
                           "explicitly with `tempfile.delete`"
       tempfile
     end
-    end
 
     def connection(opts)
       opts[:header_params]['Content-Type'] == 'multipart/form-data' ? connection_multipart : connection_regular

samples/client/echo_api/ruby-faraday/lib/openapi_client/api_client.rb

@@ -164,16 +164,22 @@ module OpenapiClient
       request.options.on_data = Proc.new do |chunk, overall_received_bytes|
         stream << chunk
       end
+
       stream
     end
 
     def deserialize_file(response, stream)
       body     = response.body
-      if @config.return_binary_data == true
-        # return byte stream
       encoding = body.encoding
-        stream.join.force_encoding(encoding)
+
-      else
+      # reconstruct content
+      content = stream.join
+      content = content.unpack('m').join if response.headers['Content-Transfer-Encoding'] == 'binary'
+      content = content.force_encoding(encoding)
+
+      # return byte stream
+      return content if @config.return_binary_data == true
+
       # return file instead of binary data
       content_disposition = response.headers['Content-Disposition']
       if content_disposition && content_disposition =~ /filename=/i
@@ -183,17 +189,17 @@ module OpenapiClient
         prefix = 'download-'
       end
       prefix = prefix + '-' unless prefix.end_with?('-')
-        encoding = body.encoding
+
       tempfile = Tempfile.open(prefix, @config.temp_folder_path, encoding: encoding)
-        tempfile.write(stream.join.force_encoding(encoding))
+      tempfile.write(content)
       tempfile.close
+
       config.logger.info "Temp file written to #{tempfile.path}, please copy the file to a proper folder "\
                           "with e.g. `FileUtils.cp(tempfile.path, '/new/file/path')` otherwise the temp file "\
                           "will be deleted automatically with GC. It's also recommended to delete the temp file "\
                           "explicitly with `tempfile.delete`"
       tempfile
     end
-    end
 
     def connection(opts)
       opts[:header_params]['Content-Type'] == 'multipart/form-data' ? connection_multipart : connection_regular

samples/client/petstore/ruby-faraday/lib/petstore/api_client.rb

@@ -164,16 +164,22 @@ module Petstore
       request.options.on_data = Proc.new do |chunk, overall_received_bytes|
         stream << chunk
       end
+
       stream
     end
 
     def deserialize_file(response, stream)
       body     = response.body
-      if @config.return_binary_data == true
-        # return byte stream
       encoding = body.encoding
-        stream.join.force_encoding(encoding)
+
-      else
+      # reconstruct content
+      content = stream.join
+      content = content.unpack('m').join if response.headers['Content-Transfer-Encoding'] == 'binary'
+      content = content.force_encoding(encoding)
+
+      # return byte stream
+      return content if @config.return_binary_data == true
+
       # return file instead of binary data
       content_disposition = response.headers['Content-Disposition']
       if content_disposition && content_disposition =~ /filename=/i
@@ -183,17 +189,17 @@ module Petstore
         prefix = 'download-'
       end
       prefix = prefix + '-' unless prefix.end_with?('-')
-        encoding = body.encoding
+
       tempfile = Tempfile.open(prefix, @config.temp_folder_path, encoding: encoding)
-        tempfile.write(stream.join.force_encoding(encoding))
+      tempfile.write(content)
       tempfile.close
+
       config.logger.info "Temp file written to #{tempfile.path}, please copy the file to a proper folder "\
                           "with e.g. `FileUtils.cp(tempfile.path, '/new/file/path')` otherwise the temp file "\
                           "will be deleted automatically with GC. It's also recommended to delete the temp file "\
                           "explicitly with `tempfile.delete`"
       tempfile
     end
-    end
 
     def connection(opts)
       opts[:header_params]['Content-Type'] == 'multipart/form-data' ? connection_multipart : connection_regular