From d2f685eed74fb7b345bf1a75b6023d62d86a1a52 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 18 Dec 2017 07:15:07 +0000
Subject: [PATCH] io.c: opening external command

* io.c (rb_io_open_generic): try to open the named file as usual,
  if klass is not IO nor File, so that Errno::ENOENT will be
  raised probably.  calling on File will be same in the future.

From: Nobuyoshi Nakada <nobu@ruby-lang.org>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61320 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 io.c                 | 16 +++++-----------
 test/ruby/test_io.rb |  5 +++--
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/io.c b/io.c
index a8ed4f0433..24f721e8fd 100644
--- a/io.c
+++ b/io.c
@@ -7088,17 +7088,11 @@ rb_io_open_generic(VALUE klass, VALUE filename, int oflags, int fmode,
 		   const convconfig_t *convconfig, mode_t perm)
 {
     VALUE cmd;
-    if (!NIL_P(cmd = check_pipe_command(filename))) {
-	if (klass != rb_cIO) {
-	    ID func = rb_frame_this_func();
-	    VALUE fname = rb_id2str(func);
-	    static const char MSG[] = "IO.%"PRIsVALUE" called on %"PRIsVALUE" to invoke external command";
-	    if (klass == rb_cFile) {
-		rb_warn(MSG, fname, klass);
-	    }
-	    else {
-		rb_raise(rb_eArgError, MSG, fname, klass);
-	    }
+    const int warn = klass == rb_cFile;
+    if ((warn || klass == rb_cIO) && !NIL_P(cmd = check_pipe_command(filename))) {
+	if (warn) {
+	    rb_warn("IO.%"PRIsVALUE" called on File to invoke external command",
+		    rb_id2str(rb_frame_this_func()));
 	}
 	return pipe_open_s(cmd, rb_io_oflags_modestr(oflags), fmode, convconfig);
     }
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 4f6027d8c9..bb16953e99 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -2185,16 +2185,17 @@ class TestIO < Test::Unit::TestCase
   end
 
   def test_read_command
+    assert_equal("foo\n", IO.read("|echo foo"))
     assert_warn(/invoke external command/) do
       File.read("|#{EnvUtil.rubybin} -e puts")
     end
     assert_warn(/invoke external command/) do
       File.binread("|#{EnvUtil.rubybin} -e puts")
     end
-    assert_raise_with_message(ArgumentError, /invoke external command/) do
+    assert_raise(Errno::ENOENT) do
       Class.new(IO).read("|#{EnvUtil.rubybin} -e puts")
     end
-    assert_raise_with_message(ArgumentError, /invoke external command/) do
+    assert_raise(Errno::ENOENT) do
       Class.new(IO).binread("|#{EnvUtil.rubybin} -e puts")
     end
   end