Use String#dup in Excon::Utils#binary_encode for frozen string

.travis.yml

@@ -12,7 +12,12 @@ rvm:
   - 2.4
   - 2.5
   - 2.6
+  - ruby-head
 script:
   - "bundle exec shindont"
   - "bundle exec rake spec[progress]"
 sudo: false
+
+matrix:
+  allow_failures:
+  - rvm: ruby-head

lib/excon/connection.rb

@@ -161,7 +161,7 @@ def request_call(datum)
             socket.write(request) # write out request + headers
             while true # write out body with chunked encoding
               chunk = datum[:request_block].call
-              binary_encode(chunk)
+              chunk = binary_encode(chunk)
               if chunk.length > 0
                 socket.write(chunk.length.to_s(16) << CR_NL << chunk << CR_NL)
               else
@@ -180,10 +180,10 @@ def request_call(datum)
             end
 
             # if request + headers is less than chunk size, fill with body
-            binary_encode(request)
+            request = binary_encode(request)
             chunk = body.read([datum[:chunk_size] - request.length, 0].max)
             if chunk
-              binary_encode(chunk)
+              chunk = binary_encode(chunk)
               socket.write(request << chunk)
             else
               socket.write(request) # write out request + headers

lib/excon/socket.rb

@@ -237,7 +237,7 @@ def read_block(max_length)
     end
 
     def write_nonblock(data)
-      binary_encode(data)
+      data = binary_encode(data)
       loop do
         written = nil
         begin

lib/excon/utils.rb

@@ -12,7 +12,13 @@ module Utils
 
     def binary_encode(string)
       if FORCE_ENC && string.encoding != Encoding::ASCII_8BIT
-        string.force_encoding('BINARY')
+        if string.frozen?
+          string.dup.force_encoding('BINARY')
+        else
+          string.force_encoding('BINARY')
+        end
+      else
+        string
       end
     end
 
@@ -89,29 +95,29 @@ def query_string(datum)
     def split_header_value(str)
       return [] if str.nil?
       str = str.dup.strip
-      binary_encode(str)
+      str = binary_encode(str)
       str.scan(%r'\G((?:"(?:\\.|[^"])+?"|[^",]+)+)
                     (?:,\s*|\Z)'xn).flatten
     end
 
     # Escapes HTTP reserved and unwise characters in +str+
     def escape_uri(str)
       str = str.dup
-      binary_encode(str)
+      str = binary_encode(str)
       str.gsub(UNESCAPED) { "%%%02X" % $1[0].ord }
     end
 
     # Unescapes HTTP reserved and unwise characters in +str+
     def unescape_uri(str)
       str = str.dup
-      binary_encode(str)
+      str = binary_encode(str)
       str.gsub(ESCAPED) { $1.hex.chr }
     end
 
     # Unescape form encoded values in +str+
     def unescape_form(str)
       str = str.dup
-      binary_encode(str)
+      str = binary_encode(str)
       str.gsub!(/\+/, ' ')
       str.gsub(ESCAPED) { $1.hex.chr }
     end