ARGF#read_nonblock

argf_read_nonblock.patch

diff --git a/kernel/common/argf.rb b/kernel/common/argf.rb
index c9f80dd..c710116 100644
--- a/kernel/common/argf.rb
+++ b/kernel/common/argf.rb
@@ -402,6 +402,33 @@ module Rubinius
 
     alias_method :to_a, :readlines
 
+    def read_nonblock(maxlen, output=nil, opts={})
+      if output.is_a?(Hash)
+        opts = output
+        output = nil
+      end
+
+      output ||= default_value
+
+      unless advance!
+        output.clear
+        raise EOFError, "ARGF at end"
+      end
+
+      begin
+        ret = @stream.read_nonblock(maxlen, output, opts)
+        return ret unless ret.is_a?(Hash)
+      rescue EOFError => e
+        raise e if @use_stdin_only
+
+        @stream.close
+        @advance = true
+        advance! or raise e
+      end
+
+      return output
+    end
+
     def readpartial(maxlen, output=nil)
       output ||= default_value
 
diff --git a/spec/custom/helpers/ruby_exe_pipe.rb b/spec/custom/helpers/ruby_exe_pipe.rb
new file mode 100644
index 0000000..6ac99d0
--- /dev/null
+++ b/spec/custom/helpers/ruby_exe_pipe.rb
@@ -0,0 +1,9 @@
+class Object
+  def ruby_exe_pipe(code, opts={})
+    pipe_mode = opts.delete(:pipe_mode) || 'r'
+    f = IO.popen(ruby_cmd(code, opts), pipe_mode)
+    yield f
+  ensure
+    f.close if f && !f.closed?
+  end
+end
diff --git a/spec/custom/mspec.rb b/spec/custom/mspec.rb
index ee009a1..229d6b2 100644
--- a/spec/custom/mspec.rb
+++ b/spec/custom/mspec.rb
@@ -13,3 +13,4 @@ if defined?(RUBY_ENGINE) && RUBY_ENGINE == 'rbx'
 end
 
 require 'spec/custom/utils/script'
+require 'spec/custom/helpers/ruby_exe_pipe'
diff --git a/spec/ruby/core/argf/read_nonblock_spec.rb b/spec/ruby/core/argf/read_nonblock_spec.rb
new file mode 100644
index 0000000..7a53161
--- /dev/null
+++ b/spec/ruby/core/argf/read_nonblock_spec.rb
@@ -0,0 +1,78 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../shared/read', __FILE__)
+require File.expand_path('../shared/readpartial', __FILE__)
+
+describe "ARGF.read_nonblock" do
+  it_behaves_like :argf_read, :read_nonblock
+  it_behaves_like :argf_readpartial, :read_nonblock
+
+  context "when ARGF is not readable yet" do
+    context "when exception option is not passed" do
+      it "raises an IO::WaitReadable exception if ARGF is not readable yet" do
+        output = ruby_exe <<-STR, escape: true
+          begin
+            ARGF.read_nonblock(1)
+          rescue IO::WaitReadable => e
+            print "IO::WaitReadable raised"
+          end
+        STR
+        output.should == "IO::WaitReadable raised"
+      end
+    end
+
+    context "when exception option is set to false" do
+      it "returns :wait_readable" do
+        ruby_exe("print ARGF.read_nonblock(1, exception: false).inspect").should == ":wait_readable"
+      end
+    end
+  end
+
+  context "when there is nothing more to read" do
+    context "when exception option is not passed" do
+      it "raises EOFError when there is nothing more to read" do
+        ruby_exe_pipe(<<-STR, escape: true, pipe_mode: "r+") do |f|
+          $stdout.sync
+          begin
+            ARGF.read_nonblock(1)
+          rescue EOFError
+            print "EOFError raised"
+          end
+        STR
+          f.close_write
+          f.read.should == "EOFError raised"
+        end
+      end
+    end
+
+    context "when exception option is set to false" do
+      it "returns nil" do
+        ruby_exe_pipe(<<-STR, escape: true, pipe_mode: "r+") do |f|
+          $stdout.sync
+          print ARGF.read_nonblock(1, exception: false).inspect
+        STR
+          f.close_write
+          f.read.should == "nil"
+        end
+      end
+    end
+  end
+
+  it "reads a maximum number of bytes once it is ready for reading" do
+    ruby_exe_pipe("print ARGF.read_nonblock(1)", escape: true, pipe_mode: "r+") do |f|
+      f.write("a")
+      f.read(1).should == "a"
+    end
+  end
+
+  context "when exception option is set to false" do
+    it "raises an EOFError if the exception was raised while reading the last file" do
+      argv [@file1_name, @file2_name] do
+        ARGF.send(@method, @file1.size)
+        ARGF.send(@method, 1)
+        ARGF.send(@method, @file2.size)
+        ARGF.send(@method, 1, exception: false).should be_nil
+        lambda { ARGF.send(@method, 1, exception: false) }.should raise_error(EOFError)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/argf/readpartial_spec.rb b/spec/ruby/core/argf/readpartial_spec.rb
index bd3f8d9..237956b 100644
--- a/spec/ruby/core/argf/readpartial_spec.rb
+++ b/spec/ruby/core/argf/readpartial_spec.rb
@@ -1,75 +1,8 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../shared/read', __FILE__)
+require File.expand_path('../shared/readpartial', __FILE__)
 
 describe "ARGF.readpartial" do
   it_behaves_like :argf_read, :readpartial
-
-  before :each do
-    @file1_name = fixture __FILE__, "file1.txt"
-    @file2_name = fixture __FILE__, "file2.txt"
-    @stdin_name = fixture __FILE__, "stdin.txt"
-
-    @file1 = File.read @file1_name
-    @file2 = File.read @file2_name
-    @stdin = File.read @stdin_name
-  end
-
-  it "raises an ArgumentError if called without a maximum read length" do
-    argv [@file1_name] do
-      lambda { ARGF.readpartial }.should raise_error(ArgumentError)
-    end
-  end
-
-  it "reads maximum number of bytes from one file at a time" do
-    argv [@file1_name, @file2_name] do
-      len = @file1.size + @file2.size
-      ARGF.readpartial(len).should == @file1
-    end
-  end
-
-  it "clears output buffer even if EOFError is raised because ARGF is at end" do
-    begin
-      output = "to be cleared"
-
-      argv [@file1_name] do
-        ARGF.read
-        ARGF.readpartial(1, output)
-      end
-    rescue EOFError
-      output.should == ""
-    end
-  end
-
-  it "reads maximum number of bytes from one file at a time" do
-    argv [@file1_name, @file2_name] do
-      len = @file1.size + @file2.size
-      ARGF.readpartial(len).should == @file1
-    end
-  end
-
-  it "returns an empty string if EOFError is raised while reading any but the last file" do
-    argv [@file1_name, @file2_name] do
-      ARGF.readpartial(@file1.size)
-      ARGF.readpartial(1).should == ""
-    end
-  end
-
-  it "raises an EOFError if the exception was raised while reading the last file" do
-    argv [@file1_name, @file2_name] do
-      ARGF.readpartial(@file1.size)
-      ARGF.readpartial(1)
-      ARGF.readpartial(@file2.size)
-      lambda { ARGF.readpartial(1) }.should raise_error(EOFError)
-      lambda { ARGF.readpartial(1) }.should raise_error(EOFError)
-    end
-  end
-
-  it "raises an EOFError if the exception was raised while reading STDIN" do
-    ruby_str = <<-STR
-      print ARGF.readpartial(#{@stdin.size})
-      ARGF.readpartial(1) rescue print $!.class
-    STR
-    stdin = ruby_exe(ruby_str, args: "< #{@stdin_name}", escape: true)
-    stdin.should == @stdin + "EOFError"
-  end
+  it_behaves_like :argf_readpartial, :readpartial
 end
diff --git a/spec/ruby/core/argf/shared/readpartial.rb b/spec/ruby/core/argf/shared/readpartial.rb
new file mode 100644
index 0000000..bd777c1
--- /dev/null
+++ b/spec/ruby/core/argf/shared/readpartial.rb
@@ -0,0 +1,70 @@
+describe :argf_readpartial, shared: true do
+  before :each do
+    @file1_name = fixture __FILE__, "file1.txt"
+    @file2_name = fixture __FILE__, "file2.txt"
+    @stdin_name = fixture __FILE__, "stdin.txt"
+
+    @file1 = File.read @file1_name
+    @file2 = File.read @file2_name
+    @stdin = File.read @stdin_name
+  end
+
+  it "raises an ArgumentError if called without a maximum read length" do
+    argv [@file1_name] do
+      lambda { ARGF.send(@method) }.should raise_error(ArgumentError)
+    end
+  end
+
+  it "reads maximum number of bytes from one file at a time" do
+    argv [@file1_name, @file2_name] do
+      len = @file1.size + @file2.size
+      ARGF.send(@method, len).should == @file1
+    end
+  end
+
+  it "clears output buffer even if EOFError is raised because ARGF is at end" do
+    begin
+      output = "to be cleared"
+
+      argv [@file1_name] do
+        ARGF.read
+        ARGF.send(@method, 1, output)
+      end
+    rescue EOFError
+      output.should == ""
+    end
+  end
+
+  it "reads maximum number of bytes from one file at a time" do
+    argv [@file1_name, @file2_name] do
+      len = @file1.size + @file2.size
+      ARGF.send(@method, len).should == @file1
+    end
+  end
+
+  it "returns an empty string if EOFError is raised while reading any but the last file" do
+    argv [@file1_name, @file2_name] do
+      ARGF.send(@method, @file1.size)
+      ARGF.send(@method, 1).should == ""
+    end
+  end
+
+  it "raises an EOFError if the exception was raised while reading the last file" do
+    argv [@file1_name, @file2_name] do
+      ARGF.send(@method, @file1.size)
+      ARGF.send(@method, 1)
+      ARGF.send(@method, @file2.size)
+      lambda { ARGF.send(@method, 1) }.should raise_error(EOFError)
+      lambda { ARGF.send(@method, 1) }.should raise_error(EOFError)
+    end
+  end
+
+  it "raises an EOFError if the exception was raised while reading STDIN" do
+    ruby_str = <<-STR
+      print ARGF.#{@method}(#{@stdin.size})
+      ARGF.#{@method}(1) rescue print $!.class
+    STR
+    stdin = ruby_exe(ruby_str, args: "< #{@stdin_name}", escape: true)
+    stdin.should == @stdin + "EOFError"
+  end
+end