From 72bf77fb30fbc97e9dcbfe50d0f62f2f40c93ae3 Mon Sep 17 00:00:00 2001
From: matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 25 Dec 2007 06:44:58 +0000
Subject: * io.c (rb_io_external_encoding): should return nil for  
 pass-through write IO.  [ruby-dev:32740]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14672 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 io.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'io.c')

diff --git a/io.c b/io.c
index 9556b98ff6..41449beb33 100644
--- a/io.c
+++ b/io.c
@@ -5921,6 +5921,7 @@ rb_io_s_read(int argc, VALUE *argv, VALUE io)
  *     io.external_encoding   => encoding
  *
  *  Returns the Encoding object that represents the encoding of the file.
+ *  If io is write mode and no encoding is specified, returns <code>nil</code>.
  */
 
 static VALUE
@@ -5935,6 +5936,11 @@ rb_io_external_encoding(VALUE io)
     if (!fptr->enc && fptr->fd == 0) {
 	fptr->enc = rb_default_external_encoding();
     }
+    if (fptr->mode & FMODE_WRITABLE) {
+	if (fptr->enc)
+	    return rb_enc_from_encoding(fptr->enc);
+	return Qnil;
+    }
     return rb_enc_from_encoding(io_read_encoding(fptr));
 }
 
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