initial commit

16 files changed, 2387 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 000000000..ceeb05b41
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/tmp
diff --git a/README.md b/README.md
new file mode 100644
index 000000000..01d29521a
--- /dev/null
+++ b/README.md
@@ -0,0 +1,5 @@
+mruby-io
+========
+
+under construction
+
diff --git a/include/mruby/ext/io.h b/include/mruby/ext/io.h
new file mode 100644
index 000000000..7ecf0a4a4
--- /dev/null
+++ b/include/mruby/ext/io.h
@@ -0,0 +1,60 @@
+/*
+** io.h - IO class
+*/
+
+#ifndef MRUBY_IO_H
+#define MRUBY_IO_H
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#include <errno.h>
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+
+struct mrb_io {
+  int fd;                                 /* file descriptor          */
+  int fd2;                                /* file descriptor          */
+  int pid;                                /* child's pid (for pipes)  */
+};
+
+struct mrb_io_type {
+  const char *struct_name;
+  void (*dfree)(mrb_state *mrb, void *);
+};
+
+#define FMODE_READABLE             0x00000001
+#define FMODE_WRITABLE             0x00000002
+#define FMODE_READWRITE            (FMODE_READABLE|FMODE_WRITABLE)
+#define FMODE_BINMODE              0x00000004
+#define FMODE_SYNC                 0x00000008
+#define FMODE_TTY                  0x00000010
+#define FMODE_DUPLEX               0x00000020
+#define FMODE_APPEND               0x00000040
+#define FMODE_CREATE               0x00000080
+#define FMODE_WSPLIT               0x00000200
+#define FMODE_WSPLIT_INITIALIZED   0x00000400
+#define FMODE_TRUNC                0x00000800
+#define FMODE_TEXTMODE             0x00001000
+#define FMODE_SETENC_BY_BOM        0x00100000
+
+#define E_IO_ERROR                 (mrb_class_obj_get(mrb, "IOError"))
+#define E_EOF_ERROR                (mrb_class_obj_get(mrb, "EOFError"))
+
+mrb_value mrb_open_file(mrb_state *mrb, int argc, mrb_value *argv, mrb_value io);
+void fptr_finalize(mrb_state *mrb, struct mrb_io *fptr, int noraise);
+mrb_value mrb_file_exist(mrb_state *mrb, mrb_value fname);
+
+#if defined(__cplusplus)
+} /* extern "C" { */
+#endif
+#endif /* MRUBY_IO_H */
diff --git a/mrbgem.rake b/mrbgem.rake
new file mode 100644
index 000000000..10e192c45
--- /dev/null
+++ b/mrbgem.rake
@@ -0,0 +1,6 @@
+MRuby::Gem::Specification.new('mruby-io') do |spec|
+  spec.license = 'MIT'
+  spec.authors = 'Internet Initiative Japan'
+
+  spec.cc.include_paths << "#{build.root}/src"
+end
diff --git a/mrblib/file.rb b/mrblib/file.rb
new file mode 100644
index 000000000..566085066
--- /dev/null
+++ b/mrblib/file.rb
@@ -0,0 +1,108 @@
+class File < IO
+  include Enumerable
+
+  class FileError < Exception; end
+  class NoFileError < FileError; end
+  class UnableToStat < FileError; end
+  class PermissionError < FileError; end
+
+  attr_accessor :path
+
+  def initialize(fd_or_path, mode = "r", perm = 0666)
+    self._bless
+    if fd_or_path.kind_of? Fixnum
+      super(fd_or_path, mode)
+    else
+      @path = fd_or_path
+
+      perm = 0666  unless perm.is_a? Fixnum
+      fd = IO.sysopen(@path, mode, perm)
+      if fd < 0 && Object.const_defined?(:Errno)
+        begin
+          Errno.handle @path
+        rescue Errno::EMFILE
+          GC.run(true)
+          fd = IO.sysopen(@path, mode, perm)
+          Errno.handle if fd < 0
+        end
+      elsif fd < 0
+        raise NoFileError.new "no such file or directory"
+      end
+      super(fd, mode)
+    end
+  end
+
+  def self.join(*names)
+    if names.size == 0
+      ""
+    elsif names.size == 1
+      names[0]
+    else
+      if names[0][-1] == File::SEPARATOR
+        s = names[0][0..-2]
+      else
+        s = names[0].dup
+      end
+      (1..names.size-2).each { |i|
+        t = names[i]
+        if t[0] == File::SEPARATOR and t[-1] == File::SEPARATOR
+          t = t[1..-2]
+        elsif t[0] == File::SEPARATOR
+          t = t[1..-1]
+        elsif t[-1] == File::SEPARATOR
+          t = t[0..-2]
+        end
+        s += File::SEPARATOR + t if t != ""
+      }
+      if names[-1][0] == File::SEPARATOR
+        s += File::SEPARATOR + names[-1][1..-1]
+      else
+        s += File::SEPARATOR + names[-1]
+      end
+      s
+    end
+  end
+
+  def self.directory?(file)
+    FileTest.directory?(file)
+  end
+
+  def self.exist?(file)
+    FileTest.exist?(file)
+  end
+
+  def self.exists?(file)
+    FileTest.exists?(file)
+  end
+
+  def self.file?(file)
+    FileTest.file?(file)
+  end
+
+  def self.pipe?(file)
+    FileTest.pipe?(file)
+  end
+
+  def self.size?(file)
+    FileTest.size?(file)
+  end
+
+  def self.socket?(file)
+    FileTest.socket?(file)
+  end
+
+  def self.symlink?(file)
+    FileTest.symlink?(file)
+  end
+
+  def self.zero?(file)
+    FileTest.zero?(file)
+  end
+
+  def self.extname(filename)
+    fname = self.basename(filename)
+    return '' if fname[0] == '.' || fname.index('.').nil?
+    ext = fname.split('.').last
+    ext.empty? ? '' : ".#{ext}"
+  end
+end
diff --git a/mrblib/file_constants.rb b/mrblib/file_constants.rb
new file mode 100644
index 000000000..c2552bf56
--- /dev/null
+++ b/mrblib/file_constants.rb
@@ -0,0 +1,31 @@
+class File
+  module Constants
+    NULL = "/dev/null"
+
+    RDONLY   = 0
+    WRONLY   = 1
+    RDWR     = 2
+    NONBLOCK = 4
+    APPEND   = 8
+
+    BINARY   = 0
+    SYNC     = 128
+    NOFOLLOW = 256
+    CREAT    = 512
+    TRUNC    = 1024
+    EXCL     = 2048
+
+    NOCTTY   = 131072
+    DSYNC    = 4194304
+
+    FNM_SYSCASE  = 0
+    FNM_NOESCAPE = 1
+    FNM_PATHNAME = 2
+    FNM_DOTMATCH = 4
+    FNM_CASEFOLD = 8
+  end
+end
+
+class File
+  include File::Constants
+end
diff --git a/mrblib/io.rb b/mrblib/io.rb
new file mode 100644
index 000000000..3c679d3f7
--- /dev/null
+++ b/mrblib/io.rb
@@ -0,0 +1,271 @@
+##
+# IO
+
+class IOError < StandardError; end
+class EOFError < IOError; end
+
+class IO
+  SEEK_SET = 0
+  SEEK_CUR = 1
+  SEEK_END = 2
+
+  BUF_SIZE = 4096
+
+  def self.open(fd, mode = "r", opt = {}, &block)
+    io = self.new(fd, mode, opt)
+
+    return io  unless block
+
+    begin
+      yield io
+    ensure
+      begin
+        io.close unless io.closed?
+      rescue StandardError
+      end
+    end
+  end
+
+  def self.popen(command, mode = 'r', &block)
+    io = self._popen(command, mode)
+    return io unless block
+
+    begin
+      yield io
+    ensure
+      begin
+        io.close unless io.closed?
+      rescue IOError
+        # nothing
+      end
+    end
+  end
+
+  def write(string)
+    str = string.is_a?(String) ? string : string.to_s
+    return str.size unless str.size > 0
+
+    len = syswrite(str)
+    if str.size == len
+      @pos += len
+      return len
+    end
+
+    raise IOError
+  end
+
+  def eof?
+    # XXX: @buf のことを考えなくてよい？？
+    ret = false
+    char = ''
+
+    begin
+      char = sysread(1)
+    rescue EOFError => e
+      ret = true
+    ensure
+      _ungets(char)
+    end
+
+    ret
+  end
+  alias_method :eof, :eof?
+
+  def pos
+    raise IOError if closed?
+    @pos
+  end
+  alias_method :tell, :pos
+
+  def pos=(i)
+    seek(i, SEEK_SET)
+  end
+
+  def seek(i, whence = SEEK_SET)
+    raise IOError if closed?
+    @pos = sysseek(i, whence)
+    @buf = ''
+    0
+  end
+
+  def _read_buf
+    return @buf if @buf && @buf.size > 0
+    @buf = sysread(BUF_SIZE)
+  end
+
+  def _ungets(substr)
+    raise TypeError.new "expect String, got #{substr.class}" unless substr.is_a?(String)
+    raise IOError if @pos == 0 || @pos.nil?
+    @pos -= substr.size
+    if @buf.empty?
+      @buf = substr
+    else
+      @buf = substr + @buf
+    end
+    nil
+  end
+
+  def ungetc(char)
+    raise IOError if @pos == 0 || @pos.nil?
+    _ungets(char)
+    nil
+  end
+
+  def read(length = nil)
+    unless length.nil? or length.class == Fixnum
+      raise TypeError.new "can't convert #{length.class} into Integer"
+    end
+    if length && length < 0
+      raise ArgumentError.new "negative length: #{length} given"
+    end
+
+    str = ''
+    while 1
+      begin
+        _read_buf
+      rescue EOFError => e
+        str = nil  if str.empty?
+        break
+      end
+
+      if length && (str.size + @buf.size) >= length
+        len = length - str.size
+        str += @buf[0, len]
+        @pos += len
+        @buf = @buf[len, @buf.size - len]
+        break
+      else
+        str += @buf
+        @pos += @buf.size
+        @buf = ''
+      end
+    end
+
+    str
+  end
+
+  def readline(arg = $/, limit = nil)
+    case arg
+    when String
+      rs = arg
+    when Fixnum
+      rs = $/
+      limit = arg
+    else
+      raise ArgumentError
+    end
+
+    if rs.nil?
+      return read
+    end
+
+    if rs == ""
+      rs = $/ + $/
+    end
+
+    str = ""
+    while 1
+      begin
+        _read_buf
+      rescue EOFError => e
+        str = nil  if str.empty?
+        break
+      end
+
+      if limit && (str.size + @buf.size) >= limit
+        len = limit - str.size
+        str += @buf[0, len]
+        @pos += len
+        @buf = @buf[len, @buf.size - len]
+        break
+      elsif idx = @buf.index(rs)
+        len = idx + rs.size
+        str += @buf[0, len]
+        @pos += len
+        @buf = @buf[len, @buf.size - len]
+        break
+      else
+        str += @buf
+        @pos += @buf.size
+        @buf = ''
+      end
+    end
+
+    raise EOFError.new "end of file reached" if str.nil?
+
+    str
+  end
+
+  def gets(*args)
+    begin
+      readline(*args)
+    rescue EOFError => e
+      nil
+    end
+  end
+
+  def readchar
+    _read_buf
+    c = @buf[0]
+    @buf = @buf[1, @buf.size]
+    @pos += 1
+    c
+  end
+
+  def getc
+    begin
+      readchar
+    rescue EOFError => e
+      nil
+    end
+  end
+
+  # 15.2.20.5.3
+  def each(&block)
+    while line = self.gets
+      block.call(line)
+    end
+    self
+  end
+
+  # 15.2.20.5.4
+  def each_byte(&block)
+    while char = self.getc
+      block.call(char)
+    end
+    self
+  end
+
+  # 15.2.20.5.5
+  alias each_line each
+
+  alias each_char each_byte
+
+  def readlines
+    ary = []
+    while (line = gets)
+      ary << line
+    end
+    ary
+  end
+
+  def puts(*args)
+    i = 0
+    len = args.size
+    while i < len
+      s = args[i].to_s
+      write s
+      write "\n" if (s[-1] != "\n")
+      i += 1
+    end
+    write "\n" if len == 0
+    nil
+  end
+
+  def printf(*args)
+    write sprintf(*args)
+    nil
+  end
+
+  alias_method :to_i, :fileno
+end
diff --git a/run_test.rb b/run_test.rb
new file mode 100644
index 000000000..e83b504be
--- /dev/null
+++ b/run_test.rb
@@ -0,0 +1,33 @@
+#!/usr/bin/env ruby
+#
+# mrbgems test runner
+#
+
+gemname = File.basename(File.dirname(File.expand_path __FILE__))
+
+if __FILE__ == $0
+  repository, dir = 'https://github.com/mruby/mruby.git', 'tmp/mruby'
+  build_args = ARGV
+  build_args = ['all', 'test']  if build_args.nil? or build_args.empty?
+
+  Dir.mkdir 'tmp'  unless File.exist?('tmp')
+  unless File.exist?(dir)
+    system "git clone #{repository} #{dir}"
+  end
+
+  exit system(%Q[cd #{dir}; MRUBY_CONFIG=#{File.expand_path __FILE__} ruby minirake #{build_args.join(' ')}])
+end
+
+MRuby::Build.new do |conf|
+  toolchain :gcc
+  conf.gems.clear
+
+  conf.gem "#{root}/mrbgems/mruby-sprintf"
+  conf.gem "#{root}/mrbgems/mruby-print"
+
+  Dir.glob("#{root}/mrbgems/mruby-*") do |x|
+    conf.gem x unless x =~ /\/mruby-(print|sprintf)$/
+  end
+
+  conf.gem File.expand_path(File.dirname(__FILE__))
+end
diff --git a/src/file.c b/src/file.c
new file mode 100644
index 000000000..fe6965943
--- /dev/null
+++ b/src/file.c
@@ -0,0 +1,294 @@
+/*
+** file.c - File class
+*/
+
+#include "mruby.h"
+
+#include "mruby/ext/io.h"
+#include "mruby/class.h"
+#include "mruby/data.h"
+#include "mruby/string.h"
+#include "error.h"
+
+#include <sys/file.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <pwd.h>
+
+#define FILE_SEPARATOR "/"
+
+#ifndef LOCK_SH
+#define LOCK_SH 1
+#endif
+#ifndef LOCK_EX
+#define LOCK_EX 2
+#endif
+#ifndef LOCK_NB
+#define LOCK_NB 4
+#endif
+#ifndef LOCK_UN
+#define LOCK_UN 8
+#endif
+
+#define STAT(p, s)        stat(p, s)
+
+mrb_value
+mrb_file_s_umask(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value *argv;
+  int argc;
+  mrb_get_args(mrb, "*", &argv, &argc);
+
+  int omask = 0;
+  if (argc == 0) {
+    omask = umask(0);
+    umask(omask);
+  } else if (argc == 1) {
+    mrb_value mask = argv[0];
+    if (!mrb_nil_p(mask) && !mrb_fixnum_p(mask)) {
+      mask = mrb_check_convert_type(mrb, mask, MRB_TT_FIXNUM, "Fixnum", "to_int");
+    }
+    if (!mrb_fixnum_p(mask)) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "invalid argument type");
+    }
+    omask = umask(mrb_fixnum(mask));
+  } else {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%d for 0..1)", argc);
+  }
+  return mrb_fixnum_value(omask);
+}
+
+static mrb_value
+mrb_file_s_unlink(mrb_state *mrb, mrb_value obj)
+{
+  mrb_value *argv;
+  int n, i, argc;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+  for (i = 0, n = 0; i < argc; i++) {
+    mrb_value pathv = argv[i];
+    if (mrb_type(pathv) != MRB_TT_STRING) {
+      mrb_raisef(mrb, E_TYPE_ERROR, "can't convert %s into String", mrb_obj_classname(mrb, pathv));
+    }
+    const char *path = mrb_string_value_cstr(mrb, &pathv);;
+    if (unlink(path) < 0) {
+      mrb_sys_fail(mrb, path);
+    } else {
+      n++;
+    }
+  }
+  return mrb_fixnum_value(n);
+}
+
+static mrb_value
+mrb_file_rename_internal(mrb_state *mrb, mrb_value from, mrb_value to)
+{
+  const char *src, *dst;
+  src = mrb_string_value_cstr(mrb, &from);
+  dst = mrb_string_value_cstr(mrb, &to);
+
+  if (rename(src, dst) < 0) {
+    if (chmod(dst, 0666) == 0 &&
+        unlink(dst) == 0 &&
+        rename(src, dst) == 0)
+      return mrb_fixnum_value(0);
+    mrb_sys_fail(mrb, "mrb_file_rename_internal failed.");
+  }
+
+  return mrb_fixnum_value(0);
+}
+
+static mrb_value
+mrb_file_s_rename(mrb_state *mrb, mrb_value obj)
+{
+  mrb_value *argv;
+  int argc;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+  if (argc != 2) {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%d for 2)", argc);
+    return mrb_nil_value();
+  }
+  if (mrb_type(argv[0]) != MRB_TT_STRING) {
+    mrb_raisef(mrb, E_TYPE_ERROR, "can't convert %s into String", mrb_obj_classname(mrb, argv[0]));
+    return mrb_nil_value();
+  }
+  if (mrb_type(argv[1]) != MRB_TT_STRING) {
+    mrb_raisef(mrb, E_TYPE_ERROR, "can't convert %s into String", mrb_obj_classname(mrb, argv[1]));
+    return mrb_nil_value();
+  }
+
+  return mrb_file_rename_internal(mrb, argv[0], argv[1]);
+}
+
+
+static mrb_value
+mrb_file_dirname(mrb_state *mrb, mrb_value klass)
+{
+  char *cp, *dname;
+  mrb_int n;
+  mrb_value fname;
+
+  mrb_get_args(mrb, "s", &cp, &n);
+  fname = mrb_str_new(mrb, cp, n);
+
+  if ((dname = dirname(RSTRING_PTR(fname))) == NULL) {
+    mrb_sys_fail(mrb, "mrb_file_dirname failed.");
+  }
+
+  return mrb_str_new(mrb, dname, strlen(dname));
+}
+
+static mrb_value
+mrb_file_basename(mrb_state *mrb, mrb_value klass)
+{
+  char *cp, *bname;
+  mrb_int n;
+  mrb_value fname;
+
+  mrb_get_args(mrb, "s", &cp, &n);
+  fname = mrb_str_new(mrb, cp, n);
+
+  if ((bname = basename(RSTRING_PTR(fname))) == NULL) {
+    mrb_sys_fail(mrb, "mrb_file_basename failed.");
+  }
+
+  return mrb_str_new(mrb, bname, strlen(bname));
+}
+
+static mrb_value
+mrb_file_realpath(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value pathname, dir_string, s, result;
+  int argc;
+  char *cpath;
+
+  argc = mrb_get_args(mrb, "S|S", &pathname, &dir_string);
+  if (argc == 2) {
+    s = mrb_str_dup(mrb, dir_string);
+    s = mrb_str_append(mrb, s, mrb_str_new_cstr(mrb, FILE_SEPARATOR));
+    s = mrb_str_append(mrb, s, pathname);
+    pathname = s;
+  }
+  cpath = mrb_str_to_cstr(mrb, pathname);
+  result = mrb_str_buf_new(mrb, PATH_MAX);
+  if (realpath(cpath, RSTRING_PTR(result)) == NULL)
+    mrb_sys_fail(mrb, cpath);
+  mrb_str_resize(mrb, result, strlen(RSTRING_PTR(result)));
+  return result;
+}
+
+static mrb_value
+mrb_file_size(mrb_state *mrb, mrb_value klass)
+{
+  char *cp;
+  FILE *fp;
+  mrb_int n;
+  mrb_int filesize;
+  mrb_value filename;
+
+  mrb_get_args(mrb, "s", &cp, &n);
+  filename = mrb_str_new(mrb, cp, n);
+
+  fp = fopen(RSTRING_PTR(filename), "rb");
+  if (fp == NULL) {
+    mrb_sys_fail(mrb, "mrb_file_size failed.");
+    return mrb_nil_value();
+  }
+
+  fseek(fp, 0, SEEK_END);
+  filesize = (mrb_int) ftell(fp);
+
+  fclose(fp);
+
+  return mrb_fixnum_value(filesize);
+}
+
+mrb_value
+mrb_file__getwd(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value path;
+
+  path = mrb_str_buf_new(mrb, MAXPATHLEN);
+  if (getcwd(RSTRING_PTR(path), MAXPATHLEN) == NULL) {
+    mrb_sys_fail(mrb, "getcwd(2)");
+  }
+  mrb_str_resize(mrb, path, strlen(RSTRING_PTR(path)));
+  return path;
+}
+
+static int
+mrb_file_is_absolute_path(const char *path)
+{
+  if (path[0] == '/')
+    return 1;
+  return 0;
+}
+
+static mrb_value
+mrb_file__gethome(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value username, result;
+  char *cuser, *home;
+  int argc;
+  struct passwd *pwd;
+
+  argc = mrb_get_args(mrb, "|S", &username);
+
+  if (argc == 0) {
+    home = getenv("HOME");
+  } else {
+    cuser = mrb_str_to_cstr(mrb, username);
+    if ((pwd = getpwnam(cuser)) == NULL) {
+      return mrb_nil_value();
+    } else {
+      home = pwd->pw_dir;
+    }
+  }
+
+  if (!mrb_file_is_absolute_path(home)) {
+    if (argc && strlen(cuser) > 0) {
+      mrb_raisef(mrb, E_ARGUMENT_ERROR, "non-absolute home of ~%s", cuser);
+    } else {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "non-absolute home");
+    }
+  }
+
+  result = mrb_str_buf_new(mrb, strlen(home));
+  strcpy( RSTRING_PTR(result), home);
+  mrb_str_resize(mrb, result, strlen(RSTRING_PTR(result)));
+
+  return result;
+}
+
+void
+mrb_init_file(mrb_state *mrb)
+{
+  struct RClass *io, *file, *cnst;
+
+  io   = mrb_class_obj_get(mrb, "IO");
+  file = mrb_define_class(mrb, "File", io);
+  MRB_SET_INSTANCE_TT(file, MRB_TT_DATA);
+  mrb_define_class_method(mrb, file, "umask", mrb_file_s_umask, ARGS_REQ(1));
+  mrb_define_class_method(mrb, file, "unlink", mrb_file_s_unlink, ARGS_ANY());
+  mrb_define_class_method(mrb, file, "delete", mrb_file_s_unlink, ARGS_ANY());
+  mrb_define_class_method(mrb, file, "rename", mrb_file_s_rename, ARGS_REQ(2));
+
+  mrb_define_class_method(mrb, file, "dirname",   mrb_file_dirname,    ARGS_REQ(1));
+  mrb_define_class_method(mrb, file, "basename",  mrb_file_basename,   ARGS_REQ(1));
+  mrb_define_class_method(mrb, file, "realpath",  mrb_file_realpath,   ARGS_REQ(1)|ARGS_OPT(1));
+  mrb_define_class_method(mrb, file, "size",      mrb_file_size,       ARGS_REQ(1));
+  mrb_define_class_method(mrb, file, "_getwd", mrb_file__getwd, ARGS_NONE());
+  mrb_define_class_method(mrb, file, "_gethome", mrb_file__gethome, ARGS_OPT(1));
+
+  cnst = mrb_define_module_under(mrb, file, "Constants");
+  mrb_define_const(mrb, cnst, "LOCK_SH", mrb_fixnum_value(LOCK_SH));
+  mrb_define_const(mrb, cnst, "LOCK_EX", mrb_fixnum_value(LOCK_EX));
+  mrb_define_const(mrb, cnst, "LOCK_UN", mrb_fixnum_value(LOCK_UN));
+  mrb_define_const(mrb, cnst, "LOCK_NB", mrb_fixnum_value(LOCK_NB));
+  mrb_define_const(mrb, cnst, "SEPARATOR", mrb_str_new_cstr(mrb, FILE_SEPARATOR));
+}
diff --git a/src/file_test.c b/src/file_test.c
new file mode 100644
index 000000000..dcc6a2fd4
--- /dev/null
+++ b/src/file_test.c
@@ -0,0 +1,307 @@
+/*
+** file.c - File class
+*/
+
+#include "mruby.h"
+
+#include "mruby/ext/io.h"
+#include "mruby/class.h"
+#include "mruby/data.h"
+#include "mruby/string.h"
+#include "error.h"
+
+#include <sys/file.h>
+#include <libgen.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <pwd.h>
+
+extern struct mrb_data_type mrb_io_type;
+
+static int
+mrb_stat(mrb_state *mrb, mrb_value obj, struct stat *st)
+{
+  mrb_value tmp;
+  mrb_value io_klass, str_klass;
+
+  io_klass  = mrb_obj_value(mrb_class_obj_get(mrb, "IO"));
+  str_klass = mrb_obj_value(mrb_class_obj_get(mrb, "String"));
+
+  tmp = mrb_funcall(mrb, obj, "is_a?", 1, io_klass);
+  if (mrb_test(tmp)) {
+    struct mrb_io *fptr;
+    fptr = (struct mrb_io *)mrb_get_datatype(mrb, obj, &mrb_io_type);
+
+    if (fptr && fptr->fd >= 0) {
+      return fstat(fptr->fd, st);
+    }
+
+    mrb_raise(mrb, E_IO_ERROR, "closed stream");
+    return -1;
+  }
+
+  tmp = mrb_funcall(mrb, obj, "is_a?", 1, str_klass);
+  if (mrb_test(tmp)) {
+    return stat(mrb_string_value_cstr(mrb, &obj), st);
+  }
+
+  return -1;
+}
+
+/*
+ * Document-method: directory?
+ *
+ * call-seq:
+ *   File.directory?(file_name)   ->  true or false
+ *
+ * Returns <code>true</code> if the named file is a directory,
+ * or a symlink that points at a directory, and <code>false</code>
+ * otherwise.
+ *
+ *    File.directory?(".")
+ */
+
+mrb_value
+mrb_filetest_s_directory_p(mrb_state *mrb, mrb_value klass)
+{
+#ifndef S_ISDIR
+#   define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+#endif
+
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+  if (S_ISDIR(st.st_mode))
+    return mrb_true_value();
+
+  return mrb_false_value();
+}
+
+/*
+ * call-seq:
+ *   File.pipe?(file_name)   ->  true or false
+ *
+ * Returns <code>true</code> if the named file is a pipe.
+ */
+
+mrb_value
+mrb_filetest_s_pipe_p(mrb_state *mrb, mrb_value klass)
+{
+#ifdef S_IFIFO
+#  ifndef S_ISFIFO
+#    define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
+#  endif
+
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+  if (S_ISFIFO(st.st_mode))
+    return mrb_true_value();
+
+#endif
+  return mrb_false_value();
+}
+
+/*
+ * call-seq:
+ *   File.symlink?(file_name)   ->  true or false
+ *
+ * Returns <code>true</code> if the named file is a symbolic link.
+ */
+
+mrb_value
+mrb_filetest_s_symlink_p(mrb_state *mrb, mrb_value klass)
+{
+#ifndef S_ISLNK
+#  ifdef _S_ISLNK
+#    define S_ISLNK(m) _S_ISLNK(m)
+#  else
+#    ifdef _S_IFLNK
+#      define S_ISLNK(m) (((m) & S_IFMT) == _S_IFLNK)
+#    else
+#      ifdef S_IFLNK
+#        define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
+#      endif
+#    endif
+#  endif
+#endif
+
+#ifdef S_ISLNK
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+  if (S_ISLNK(st.st_mode))
+    return mrb_true_value();
+#endif
+
+  return mrb_false_value();
+}
+
+/*
+ * call-seq:
+ *   File.socket?(file_name)   ->  true or false
+ *
+ * Returns <code>true</code> if the named file is a socket.
+ */
+
+mrb_value
+mrb_filetest_s_socket_p(mrb_state *mrb, mrb_value klass)
+{
+#ifndef S_ISSOCK
+#  ifdef _S_ISSOCK
+#    define S_ISSOCK(m) _S_ISSOCK(m)
+#  else
+#    ifdef _S_IFSOCK
+#      define S_ISSOCK(m) (((m) & S_IFMT) == _S_IFSOCK)
+#    else
+#      ifdef S_IFSOCK
+#        define S_ISSOCK(m) (((m) & S_IFMT) == S_IFSOCK)
+#      endif
+#    endif
+#  endif
+#endif
+
+#ifdef S_ISSOCK
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+  if (S_ISSOCK(st.st_mode))
+    return mrb_true_value();
+#endif
+
+  return mrb_false_value();
+}
+
+/*
+ * call-seq:
+ *    File.exist?(file_name)    ->  true or false
+ *    File.exists?(file_name)   ->  true or false
+ *
+ * Return <code>true</code> if the named file exists.
+ */
+
+mrb_value
+mrb_filetest_s_exist_p(mrb_state *mrb, mrb_value klass)
+{
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+
+  return mrb_true_value();
+}
+
+/*
+ * call-seq:
+ *    File.file?(file_name)   -> true or false
+ *
+ * Returns <code>true</code> if the named file exists and is a
+ * regular file.
+ */
+
+mrb_value
+mrb_filetest_s_file_p(mrb_state *mrb, mrb_value klass)
+{
+#ifndef S_ISREG
+#   define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
+#endif
+
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+  if (S_ISREG(st.st_mode))
+    return mrb_true_value();
+
+  return mrb_false_value();
+}
+
+/*
+ * call-seq:
+ *    File.zero?(file_name)   -> true or false
+ *
+ * Returns <code>true</code> if the named file exists and has
+ * a zero size.
+ */
+
+mrb_value
+mrb_filetest_s_zero_p(mrb_state *mrb, mrb_value klass)
+{
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_false_value();
+  if (st.st_size == 0)
+    return mrb_true_value();
+
+  return mrb_false_value();
+}
+
+/*
+ * call-seq:
+ *    File.size?(file_name)   -> Integer or nil
+ *
+ * Returns +nil+ if +file_name+ doesn't exist or has zero size, the size of the
+ * file otherwise.
+ */
+
+mrb_value
+mrb_filetest_s_size_p(mrb_state *mrb, mrb_value klass)
+{
+  struct stat st;
+  mrb_value obj;
+
+  mrb_get_args(mrb, "o", &obj);
+
+  if (mrb_stat(mrb, obj, &st) < 0)
+    return mrb_nil_value();
+  if (st.st_size == 0)
+    return mrb_nil_value();
+
+  return mrb_fixnum_value(st.st_size);
+}
+
+
+void
+mrb_init_file_test(mrb_state *mrb)
+{
+  struct RClass *f;
+
+  f = mrb_define_class(mrb, "FileTest", mrb->object_class);
+
+  mrb_define_class_method(mrb, f, "directory?", mrb_filetest_s_directory_p, ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "exist?",     mrb_filetest_s_exist_p,     ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "exists?",    mrb_filetest_s_exist_p,     ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "file?",      mrb_filetest_s_file_p,      ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "pipe?",      mrb_filetest_s_pipe_p,      ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "size?",      mrb_filetest_s_size_p,      ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "socket?",    mrb_filetest_s_socket_p,    ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "symlink?",   mrb_filetest_s_symlink_p,   ARGS_REQ(1));
+  mrb_define_class_method(mrb, f, "zero?",      mrb_filetest_s_zero_p,      ARGS_REQ(1));
+}
diff --git a/src/io.c b/src/io.c
new file mode 100644
index 000000000..e5fe6a73f
--- /dev/null
+++ b/src/io.c
@@ -0,0 +1,755 @@
+/*
+** io.c - IO class
+*/
+
+#include "mruby.h"
+
+#include "mruby/hash.h"
+#include "mruby/data.h"
+#include "mruby/khash.h"
+#include "mruby/array.h"
+#include "mruby/class.h"
+#include "mruby/string.h"
+#include "mruby/variable.h"
+#include "mruby/ext/io.h"
+#include "error.h"
+
+static int mrb_io_modestr_to_flags(mrb_state *mrb, const char *modestr);
+static int mrb_io_modenum_to_flags(mrb_state *mrb, int modenum);
+static int mrb_io_flags_to_modenum(mrb_state *mrb, int flags);
+
+static int
+mrb_io_modestr_to_flags(mrb_state *mrb, const char *mode)
+{
+  int flags = 0;
+  const char *m = mode;
+
+  switch (*m++) {
+    case 'r':
+      flags |= FMODE_READABLE;
+      break;
+    case 'w':
+      flags |= FMODE_WRITABLE | FMODE_CREATE;
+      break;
+    case 'a':
+      flags |= FMODE_WRITABLE | FMODE_APPEND | FMODE_CREATE;
+      break;
+    default:
+      mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal access mode %s", mode);
+  }
+
+  while (*m) {
+    switch (*m++) {
+      case 'b':
+        flags |= FMODE_BINMODE;
+        break;
+      case '+':
+        flags |= FMODE_READWRITE;
+        break;
+      case ':':
+        /* XXX: PASSTHROUGH*/
+      default:
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal access mode %s", mode);
+    }
+  }
+
+  return flags;
+}
+
+static int
+mrb_io_modenum_to_flags(mrb_state *mrb, int modenum)
+{
+  int flags = 0;
+
+  switch (modenum & (O_RDONLY|O_WRONLY|O_RDWR)) {
+    case O_RDONLY:
+      flags = FMODE_READABLE;
+      break;
+    case O_WRONLY:
+      flags = FMODE_WRITABLE;
+      break;
+    case O_RDWR:
+      flags = FMODE_READWRITE;
+      break;
+  }
+
+  if (modenum & O_APPEND) {
+    flags |= FMODE_APPEND;
+  }
+  if (modenum & O_TRUNC) {
+    flags |= FMODE_TRUNC;
+  }
+  if (modenum & O_CREAT) {
+    flags |= FMODE_CREATE;
+  }
+#ifdef O_BINARY
+  if (modenum & O_BINARY) {
+    flags |= FMODE_BINMODE;
+  }
+#endif
+
+  return flags;
+}
+
+static int
+mrb_io_flags_to_modenum(mrb_state *mrb, int flags)
+{
+  int modenum = 0;
+
+  switch(flags & (FMODE_READABLE|FMODE_WRITABLE|FMODE_READWRITE)) {
+    case FMODE_READABLE:
+      modenum = O_RDONLY;
+      break;
+    case FMODE_WRITABLE:
+      modenum = O_WRONLY;
+      break;
+    case FMODE_READWRITE:
+      modenum = O_RDWR;
+      break;
+  }
+
+  if (flags & FMODE_APPEND) {
+    modenum |= O_APPEND;
+  }
+  if (flags & FMODE_TRUNC) {
+    modenum |= O_TRUNC;
+  }
+  if (flags & FMODE_CREATE) {
+    modenum |= O_CREAT;
+  }
+#ifdef O_BINARY
+  if (flags & FMODE_BINMODE) {
+    modenum |= O_BINARY
+  }
+#endif
+
+  return modenum;
+}
+
+static int
+mrb_proc_exec(const char *pname)
+{
+  const char *s;
+  s = pname;
+
+  while (*s == ' ' || *s == '\t' || *s == '\n')
+    s++;
+
+  if (!*s) {
+    errno = ENOENT;
+    return -1;
+  }
+
+  execl("/bin/sh", "sh", "-c", pname, (char *)NULL);
+  return -1;
+}
+
+static void
+mrb_io_free(mrb_state *mrb, void *ptr)
+{
+  struct mrb_io *io = (struct mrb_io *)ptr;
+  if (io != NULL) {
+    fptr_finalize(mrb, io, TRUE);
+    mrb_free(mrb, io);
+  }
+}
+
+struct mrb_data_type mrb_io_type = { "IO", mrb_io_free };
+
+static struct mrb_io*
+mrb_io_alloc(mrb_state *mrb)
+{
+  struct mrb_io *fptr;
+
+  fptr = (struct mrb_io *)mrb_malloc(mrb, sizeof(struct mrb_io));
+  fptr->fd       = -1;
+  fptr->fd2      = -1;
+  fptr->pid      = 0;
+
+  return fptr;
+}
+
+static int
+io_open(mrb_state *mrb, mrb_value path, int flags, int perm)
+{
+  const char *pat;
+  int modenum;
+
+  pat = mrb_string_value_cstr(mrb, &path);
+  modenum = mrb_io_flags_to_modenum(mrb, flags);
+
+  return open(pat, modenum, perm);
+}
+
+#ifndef NOFILE
+#define NOFILE 64
+#endif
+
+mrb_value
+mrb_io_s_popen(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value cmd, io;
+  mrb_value mode = mrb_str_new_cstr(mrb, "r");
+  mrb_value opt  = mrb_hash_new(mrb);
+
+  struct mrb_io *fptr;
+  const char *pname;
+  int pid, flags, fd, write_fd = -1;
+  int pr[2], pw[2];
+  int doexec;
+
+  mrb_get_args(mrb, "S|SH", &cmd, &mode, &opt);
+  io = mrb_obj_value(mrb_data_object_alloc(mrb, mrb_class_ptr(klass), NULL, &mrb_io_type));
+
+  pname = mrb_string_value_cstr(mrb, &cmd);
+  flags = mrb_io_modestr_to_flags(mrb, mrb_string_value_cstr(mrb, &mode));
+
+  doexec = (strcmp("-", pname) != 0);
+
+  if (((flags & FMODE_READABLE) && pipe(pr) == -1)
+      || ((flags & FMODE_WRITABLE) && pipe(pw) == -1)) {
+    mrb_sys_fail(mrb, "pipe_open failed.");
+    return mrb_nil_value();
+  }
+
+  if (!doexec) {
+    // XXX
+    fflush(stdin);
+    fflush(stdout);
+    fflush(stderr);
+  }
+
+retry:
+  switch (pid = fork()) {
+    case 0: /* child */
+      if (flags & FMODE_READABLE) {
+        close(pr[0]);
+        if (pr[1] != 1) {
+          dup2(pr[1], 1);
+          close(pr[1]);
+        }
+      }
+      if (flags & FMODE_WRITABLE) {
+        close(pw[1]);
+        if (pw[0] != 0) {
+          dup2(pw[0], 0);
+          close(pw[0]);
+        }
+      }
+
+      if (doexec) {
+        for (fd = 3; fd < NOFILE; fd++) {
+          close(fd);
+        }
+        mrb_proc_exec(pname);
+        mrb_raisef(mrb, E_IO_ERROR, "command not found: %s", pname);
+        _exit(127);
+      }
+      return mrb_nil_value();
+    case -1: /* error */
+      if (errno == EAGAIN) {
+        goto retry;
+      } else {
+        int e = errno;
+        if (flags & FMODE_READABLE) {
+          close(pr[0]);
+          close(pr[1]);
+        }
+        if (flags & FMODE_WRITABLE) {
+          close(pw[0]);
+          close(pw[1]);
+        }
+
+        errno = e;
+        mrb_sys_fail(mrb, "pipe_open failed.");
+      }
+      break;
+    default: /* parent */
+      if (pid < 0) {
+        mrb_sys_fail(mrb, "pipe_open failed.");
+        return mrb_nil_value();
+      } else {
+        if ((flags & FMODE_READABLE) && (flags & FMODE_WRITABLE)) {
+          close(pr[1]);
+          fd = pr[0];
+          close(pw[0]);
+          write_fd = pw[1];
+        } else if (flags & FMODE_READABLE) {
+          close(pr[1]);
+          fd = pr[0];
+        } else {
+          close(pw[0]);
+          fd = pw[1];
+        }
+
+        mrb_iv_set(mrb, io, mrb_intern(mrb, "@buf"), mrb_str_new_cstr(mrb, ""));
+        mrb_iv_set(mrb, io, mrb_intern(mrb, "@pos"), mrb_fixnum_value(0));
+
+        fptr = mrb_io_alloc(mrb);
+        fptr->fd   = fd;
+        fptr->fd2  = write_fd;
+        fptr->pid  = pid;
+
+        DATA_TYPE(io) = &mrb_io_type;
+        DATA_PTR(io)  = fptr;
+        return io;
+      }
+  }
+
+  return mrb_nil_value();
+}
+
+mrb_value
+mrb_io_initialize(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  mrb_int fd, flags;
+  mrb_value mode, opt;
+
+  DATA_TYPE(io) = &mrb_io_type;
+  DATA_PTR(io)  = NULL;
+
+  mode = opt = mrb_nil_value();
+
+  mrb_get_args(mrb, "i|So", &fd, &mode, &opt);
+  if (mrb_nil_p(mode)) {
+    mode = mrb_str_new_cstr(mrb, "r");
+  }
+  if (mrb_nil_p(opt)) {
+    opt = mrb_hash_new(mrb);
+  }
+
+  flags   = mrb_io_modestr_to_flags(mrb, mrb_string_value_cstr(mrb, &mode));
+
+  mrb_iv_set(mrb, io, mrb_intern(mrb, "@buf"), mrb_str_new_cstr(mrb, ""));
+  mrb_iv_set(mrb, io, mrb_intern(mrb, "@pos"), mrb_fixnum_value(0));
+
+  fptr = DATA_PTR(io);
+  if (fptr == NULL) {
+    fptr = mrb_io_alloc(mrb);
+  }
+  fptr->fd    = fd;
+
+  DATA_PTR(io) = fptr;
+
+  return io;
+}
+
+void
+fptr_finalize(mrb_state *mrb, struct mrb_io *fptr, int noraise)
+{
+  int n = 0;
+
+  if (fptr == NULL) {
+    return;
+  }
+
+  if (fptr->fd > 2) {
+    n = close(fptr->fd);
+    if (n == 0) {
+      fptr->fd = -1;
+    }
+  }
+  if (fptr->fd2 > 2) {
+    n = close(fptr->fd2);
+    if (n == 0) {
+      fptr->fd2 = -1;
+    }
+  }
+
+  if (!noraise && n != 0) {
+    mrb_sys_fail(mrb, "fptr_finalize failed.");
+  }
+}
+
+mrb_value
+mrb_io_bless(mrb_state *mrb, mrb_value io)
+{
+  if (mrb_type(io) != MRB_TT_DATA) {
+    mrb_raise(mrb, E_TYPE_ERROR, "expected IO object");
+    return mrb_nil_value();
+  }
+
+  DATA_TYPE(io) = &mrb_io_type;
+  DATA_PTR(io)  = NULL;
+  DATA_PTR(io)  = mrb_io_alloc(mrb);
+
+  return io;
+}
+
+mrb_value
+mrb_io_s_for_fd(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value io = mrb_obj_value(mrb_data_object_alloc(mrb, mrb_class_ptr(klass), NULL, &mrb_io_type));
+
+  return mrb_io_initialize(mrb, io);
+}
+
+mrb_value
+mrb_io_s_sysopen(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value path = mrb_nil_value();
+  mrb_value mode = mrb_nil_value();
+  mrb_int fd, flags, perm = -1;
+
+  mrb_get_args(mrb, "S|Si", &path, &mode, &perm);
+  if (mrb_nil_p(mode)) {
+    mode = mrb_str_new_cstr(mrb, "r");
+  }
+  if (perm < 0) {
+    perm = 0666;
+  }
+
+  flags = mrb_io_modestr_to_flags(mrb, mrb_string_value_cstr(mrb, &mode));
+  fd = io_open(mrb, path, flags, perm);
+
+  return mrb_fixnum_value(fd);
+}
+
+mrb_value
+mrb_io_sysread(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  mrb_value buf = mrb_nil_value();
+  int maxlen, ret;
+
+  mrb_get_args(mrb, "i|S", &maxlen, &buf);
+  if (maxlen < 0) {
+    return mrb_nil_value();
+  }
+
+  if (mrb_nil_p(buf)) {
+    buf = mrb_str_new(mrb, "", maxlen);
+  }
+  if (RSTRING_LEN(buf) != maxlen) {
+    buf = mrb_str_resize(mrb, buf, maxlen);
+  }
+
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+  ret = read(fptr->fd, RSTRING_PTR(buf), maxlen);
+  switch (ret) {
+    case 0: /* EOF */
+      if (maxlen == 0) {
+        buf = mrb_str_new_cstr(mrb, "");
+      } else {
+        mrb_raise(mrb, E_EOF_ERROR, "sysread failed: End of File");
+        return mrb_nil_value();
+      }
+      break;
+    case -1: /* Error */
+      mrb_raise(mrb, E_IO_ERROR, "sysread failed");
+      return mrb_nil_value();
+      break;
+    default:
+      if (RSTRING_LEN(buf) != ret) {
+        buf = mrb_str_resize(mrb, buf, ret);
+      }
+      break;
+  }
+
+  return buf;
+}
+
+mrb_value
+mrb_io_sysseek(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  int pos, offset, whence = -1;
+
+  mrb_get_args(mrb, "i|i", &offset, &whence);
+  if (whence < 0) {
+    whence = 0;
+  }
+
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+  pos = lseek(fptr->fd, offset, whence);
+  if (pos < 0) {
+    mrb_raise(mrb, E_IO_ERROR, "sysseek faield");
+    return mrb_nil_value();
+  }
+
+  return mrb_fixnum_value(pos);
+}
+
+mrb_value
+mrb_io_syswrite(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  mrb_value str, buf;
+  int length;
+
+  mrb_get_args(mrb, "S", &str);
+  if (mrb_type(str) != MRB_TT_STRING) {
+    buf = mrb_funcall(mrb, str, "to_s", 0);
+  } else {
+    buf = str;
+  }
+
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+  length = write(fptr->fd, RSTRING_PTR(buf), RSTRING_LEN(buf));
+
+  return mrb_fixnum_value(length);
+}
+
+mrb_value
+mrb_io_close(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+  if (fptr && fptr->fd < 0) {
+    mrb_raise(mrb, E_IO_ERROR, "closed stream.");
+    return mrb_nil_value();
+  }
+
+  fptr_finalize(mrb, fptr, FALSE);
+  return mrb_nil_value();
+}
+
+mrb_value
+mrb_io_closed(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+
+  if (fptr->fd >= 0) {
+    return mrb_false_value();
+  }
+
+  return mrb_true_value();
+}
+
+mrb_value
+mrb_io_pid(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+
+  if (fptr->pid > 0) {
+    return mrb_fixnum_value(fptr->pid);
+  }
+
+  return mrb_nil_value();
+}
+
+static struct timeval
+time2timeval(mrb_state *mrb, mrb_value time)
+{
+  struct timeval t;
+
+  switch (mrb_type(time)) {
+    case MRB_TT_FIXNUM:
+      t.tv_sec = mrb_fixnum(time);
+      t.tv_usec = 0;
+      break;
+
+    case MRB_TT_FLOAT:
+      t.tv_sec = mrb_float(time);
+      t.tv_usec = (mrb_float(time) - t.tv_sec) * 1000000.0;
+      break;
+
+    default:
+      mrb_raise(mrb, E_TYPE_ERROR, "wrong argument class");
+  }
+
+  return t;
+}
+
+static mrb_value
+mrb_io_select(mrb_state *mrb, mrb_value klass)
+{
+  mrb_value *argv;
+  int argc;
+  mrb_value read, write, except, timeout, list;
+  struct timeval *tp, timerec;
+  fd_set pset, rset, wset, eset;
+  fd_set *rp, *wp, *ep;
+  struct mrb_io *fptr;
+  int pending = 0;
+  mrb_value result;
+  int max = 0;
+  int interrupt_flag = 0;
+  int i, n;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+
+  if (argc < 1 || argc > 4) {
+    mrb_raisef(mrb, E_ARGUMENT_ERROR,
+        "wrong number of arguments (%d for 1..4)", argc);
+    return mrb_nil_value();
+  }
+
+  timeout = mrb_nil_value();
+  except = mrb_nil_value();
+  write = mrb_nil_value();
+  if (argc > 3)
+    timeout = argv[3];
+  if (argc > 2)
+    except = argv[2];
+  if (argc > 1)
+    write = argv[1];
+  read = argv[0];
+
+  if (mrb_nil_p(timeout)) {
+    tp = NULL;
+  } else {
+    timerec = time2timeval(mrb, timeout);
+    tp = &timerec;
+  }
+
+  FD_ZERO(&pset);
+  if (!mrb_nil_p(read)) {
+    mrb_check_type(mrb, read, MRB_TT_ARRAY);
+    rp = &rset;
+    FD_ZERO(rp);
+    for (i = 0; i < RARRAY_LEN(read); i++) {
+      fptr = (struct mrb_io *)mrb_get_datatype(mrb, RARRAY_PTR(read)[i], &mrb_io_type);
+      FD_SET(fptr->fd, rp);
+      /* XXX: .....
+      if (READ_DATA_PENDING(fptr->f)) {
+        pending++;
+        FD_SET(fileno(fptr->f), &pset);
+      }
+      */
+      if (max < fptr->fd)
+        max = fptr->fd;
+    }
+    if (pending) {
+      timerec.tv_sec = timerec.tv_usec = 0;
+      tp = &timerec;
+    }
+  } else {
+    rp = NULL;
+  }
+
+  if (!mrb_nil_p(write)) {
+    mrb_check_type(mrb, write, MRB_TT_ARRAY);
+    wp = &wset;
+    FD_ZERO(wp);
+    for (i = 0; i < RARRAY_LEN(write); i++) {
+      fptr = (struct mrb_io *)mrb_get_datatype(mrb, RARRAY_PTR(write)[i], &mrb_io_type);
+      FD_SET(fptr->fd, wp);
+      if (max < fptr->fd)
+        max = fptr->fd;
+      if (fptr->fd2 >= 0) {
+        FD_SET(fptr->fd2, wp);
+        if (max < fptr->fd2)
+          max = fptr->fd2;
+      }
+    }
+  } else {
+    wp = NULL;
+  }
+
+  if (!mrb_nil_p(except)) {
+    mrb_check_type(mrb, except, MRB_TT_ARRAY);
+    ep = &eset;
+    FD_ZERO(ep);
+    for (i = 0; i < RARRAY_LEN(except); i++) {
+      fptr = (struct mrb_io *)mrb_get_datatype(mrb, RARRAY_PTR(except)[i], &mrb_io_type);
+      FD_SET(fptr->fd, ep);
+      if (max < fptr->fd)
+        max = fptr->fd;
+      if (fptr->fd2) {
+        FD_SET(fptr->fd2, ep);
+        if (max < fptr->fd2)
+          max = fptr->fd2;
+      }
+    }
+  } else {
+    ep = NULL;
+  }
+
+  max++;
+
+retry:
+  n = select(max, rp, wp, ep, tp);
+  if (n < 0) {
+    if (errno != EINTR)
+      mrb_sys_fail(mrb, "select failed");
+    if (tp == NULL)
+      goto retry;
+    interrupt_flag = 1;
+  }
+
+  if (!pending && n == 0)
+    return mrb_nil_value();
+
+  result = mrb_ary_new_capa(mrb, 3);
+  mrb_ary_push(mrb, result, rp? mrb_ary_new(mrb) : mrb_ary_new_capa(mrb, 0));
+  mrb_ary_push(mrb, result, wp? mrb_ary_new(mrb) : mrb_ary_new_capa(mrb, 0));
+  mrb_ary_push(mrb, result, ep? mrb_ary_new(mrb) : mrb_ary_new_capa(mrb, 0));
+
+  if (interrupt_flag == 0) {
+    if (rp) {
+      list = RARRAY_PTR(result)[0];
+      for (i = 0; i < RARRAY_LEN(read); i++) {
+        fptr = (struct mrb_io *)mrb_get_datatype(mrb, RARRAY_PTR(read)[i], &mrb_io_type);
+        if (FD_ISSET(fptr->fd, rp) ||
+            FD_ISSET(fptr->fd, &pset)) {
+          mrb_ary_push(mrb, list, RARRAY_PTR(read)[i]);
+        }
+      }
+    }
+
+    if (wp) {
+      list = RARRAY_PTR(result)[1];
+      for (i = 0; i < RARRAY_LEN(write); i++) {
+        fptr = (struct mrb_io *)mrb_get_datatype(mrb, RARRAY_PTR(write)[i], &mrb_io_type);
+        if (FD_ISSET(fptr->fd, wp)) {
+          mrb_ary_push(mrb, list, RARRAY_PTR(write)[i]);
+        } else if (fptr->fd2 && FD_ISSET(fptr->fd2, wp)) {
+          mrb_ary_push(mrb, list, RARRAY_PTR(write)[i]);
+        }
+      }
+    }
+
+    if (ep) {
+      list = RARRAY_PTR(result)[2];
+      for (i = 0; i < RARRAY_LEN(except); i++) {
+        fptr = (struct mrb_io *)mrb_get_datatype(mrb, RARRAY_PTR(except)[i], &mrb_io_type);
+        if (FD_ISSET(fptr->fd, ep)) {
+          mrb_ary_push(mrb, list, RARRAY_PTR(except)[i]);
+        } else if (fptr->fd2 && FD_ISSET(fptr->fd2, wp)) {
+          mrb_ary_push(mrb, list, RARRAY_PTR(except)[i]);
+        }
+      }
+    }
+  }
+
+  return result;
+}
+
+mrb_value
+mrb_io_fileno(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+  return mrb_fixnum_value(fptr->fd);
+}
+
+void
+mrb_init_io(mrb_state *mrb)
+{
+  struct RClass *io;
+
+  io      = mrb_define_class(mrb, "IO", mrb->object_class);
+  MRB_SET_INSTANCE_TT(io, MRB_TT_DATA);
+
+  mrb_include_module(mrb, io, mrb_class_get(mrb, "Enumerable")); /* 15.2.20.3 */
+
+  mrb_define_class_method(mrb, io, "_popen",  mrb_io_s_popen,   ARGS_ANY());
+  mrb_define_class_method(mrb, io, "for_fd",  mrb_io_s_for_fd,  ARGS_REQ(1)|ARGS_OPT(2));
+  mrb_define_class_method(mrb, io, "sysopen", mrb_io_s_sysopen, ARGS_ANY());
+
+  mrb_define_method(mrb, io, "_bless",     mrb_io_bless,       ARGS_NONE());
+  mrb_define_method(mrb, io, "initialize", mrb_io_initialize,  ARGS_ANY());    /* 15.2.20.5.21 (x)*/
+  mrb_define_method(mrb, io, "sysread",    mrb_io_sysread,     ARGS_ANY());
+  mrb_define_method(mrb, io, "sysseek",    mrb_io_sysseek,     ARGS_REQ(1));
+  mrb_define_method(mrb, io, "syswrite",   mrb_io_syswrite,    ARGS_REQ(1));
+  mrb_define_method(mrb, io, "close",      mrb_io_close,       ARGS_NONE());   /* 15.2.20.5.1 */
+  mrb_define_method(mrb, io, "closed?",    mrb_io_closed,      ARGS_NONE());   /* 15.2.20.5.2 */
+  mrb_define_method(mrb, io, "pid",        mrb_io_pid,         ARGS_NONE());   /* 15.2.20.5.2 */
+  mrb_define_method(mrb, io, "fileno",     mrb_io_fileno,      ARGS_NONE());
+
+  mrb_gv_set(mrb, mrb_intern(mrb, "$/"), mrb_str_new_cstr(mrb, "\n"));
+}
diff --git a/src/mruby_io_gem.c b/src/mruby_io_gem.c
new file mode 100644
index 000000000..6880e6678
--- /dev/null
+++ b/src/mruby_io_gem.c
@@ -0,0 +1,20 @@
+#include "mruby.h"
+
+void mrb_init_io(mrb_state *mrb);
+void mrb_init_file(mrb_state *mrb);
+void mrb_init_file_test(mrb_state *mrb);
+
+#define DONE mrb_gc_arena_restore(mrb, 0)
+
+void
+mrb_mruby_io_gem_init(mrb_state* mrb)
+{
+  mrb_init_io(mrb); DONE;
+  mrb_init_file(mrb); DONE;
+  mrb_init_file_test(mrb); DONE;
+}
+
+void
+mrb_mruby_io_gem_final(mrb_state* mrb)
+{
+}
diff --git a/test/file.rb b/test/file.rb
new file mode 100644
index 000000000..f1bef32e5
--- /dev/null
+++ b/test/file.rb
@@ -0,0 +1,75 @@
+##
+# IO Test
+
+assert('File', '15.2.21') do
+  File.class == Class
+end
+
+assert('File', '15.2.21.2') do
+  File.superclass == IO
+end
+
+assert('File TEST SETUP') do
+  MRubyIOTestUtil.io_test_setup
+end
+
+assert('File#initialize', '15.2.21.4.1') do
+  io = File.open($mrbtest_io_rfname, "r")
+  assert_nil io.close
+  assert_raise IOError do
+    io.close
+  end
+end
+
+assert('File#path', '15.2.21.4.2') do
+  io = File.open($mrbtest_io_rfname, "r")
+  assert_equal $mrbtest_io_msg + "\n", io.read
+  assert_equal $mrbtest_io_rfname, io.path
+  io.close
+  assert_equal $mrbtest_io_rfname, io.path
+  io.closed?
+end
+
+assert('File.dirname') do
+  path = File.dirname("filename")
+  "." == path
+end
+
+assert('File.basename') do
+  name = File.basename("../somewhere/filename")
+  name == "filename"
+end
+
+assert('File.extname') do
+  assert_equal '.txt', File.extname('foo/foo.txt')
+  assert_equal '.gz',  File.extname('foo/foo.tar.gz')
+  assert_equal '', File.extname('foo/bar')
+  assert_equal '', File.extname('foo/.bar')
+  assert_equal '', File.extname('foo.txt/bar')
+  assert_equal '', File.extname('.foo')
+end
+
+assert('File.size') do
+  File.size($mrbtest_io_rfname) == $mrbtest_io_msg.size + 1  and
+  File.size($mrbtest_io_wfname) == 0
+end
+
+assert('File.join') do
+  File.join() == "" and
+  File.join("a") == "a" and
+  File.join("/a") == "/a" and
+  File.join("a/") == "a/" and
+  File.join("a", "b", "c") == "a/b/c" and
+  File.join("/a", "b", "c") == "/a/b/c" and
+  File.join("a", "b", "c/") == "a/b/c/" and
+  File.join("a/", "/b/", "/c") == "a/b/c"
+end
+
+assert('File.realpath') do
+  usrbin = IO.popen("cd bin; /bin/pwd -P") { |f| f.read.chomp }
+  assert_equal usrbin, File.realpath("bin")
+end
+
+assert('File TEST CLEANUP') do
+  assert_nil MRubyIOTestUtil.io_test_cleanup
+end
diff --git a/test/file_test.rb b/test/file_test.rb
new file mode 100644
index 000000000..296679a6b
--- /dev/null
+++ b/test/file_test.rb
@@ -0,0 +1,90 @@
+##
+# FileTest
+
+assert('FileTest TEST SETUP') do
+  MRubyIOTestUtil.io_test_setup
+end
+
+assert("FileTest.directory?") do
+  assert_equal true,  FileTest.directory?("/tmp")
+  assert_equal false, FileTest.directory?("/bin/sh")
+end
+
+assert("FileTest.exist?") do
+  assert_equal true,  FileTest.exist?($mrbtest_io_rfname), "filename - exist"
+  assert_equal false, FileTest.exist?($mrbtest_io_rfname + "-"), "filename - not exist"
+  io = IO.new(IO.sysopen($mrbtest_io_rfname))
+  assert_equal true,  FileTest.exist?(io), "io obj - exist"
+  io.close
+  assert_equal true, io.closed?
+  assert_raise IOError do
+    FileTest.exist?(io)
+  end
+end
+
+assert("FileTest.file?") do
+  assert_equal false, FileTest.file?("/tmp")
+  assert_equal true,  FileTest.file?("/bin/sh")
+end
+
+assert("FileTest.pipe?") do
+  io = IO.popen("ls")
+  assert_equal true,  FileTest.pipe?(io)
+  assert_equal false, FileTest.pipe?("/tmp")
+end
+
+assert("FileTest.size?") do
+  assert_equal $mrbtest_io_msg.size+1, FileTest.size?($mrbtest_io_rfname)
+  assert_equal nil, FileTest.size?($mrbtest_io_wfname)
+  assert_equal nil, FileTest.size?("not-exist-test-target-file")
+
+  fp1 = File.open($mrbtest_io_rfname)
+  fp2 = File.open($mrbtest_io_wfname)
+  assert_equal $mrbtest_io_msg.size+1,  FileTest.size?(fp1)
+  assert_equal nil, FileTest.size?(fp2)
+  fp1.close
+  fp2.close
+
+  assert_raise IOError do
+    FileTest.size?(fp1)
+  end
+  assert_raise IOError do
+    FileTest.size?(fp2)
+  end
+
+  fp1.closed? && fp2.closed?
+end
+
+assert("FileTest.socket?") do
+  skip
+end
+
+assert("FileTest.symlink?") do
+  skip
+end
+
+assert("FileTest.zero?") do
+  assert_equal false, FileTest.zero?($mrbtest_io_rfname)
+  assert_equal true,  FileTest.zero?($mrbtest_io_wfname)
+  assert_equal false, FileTest.zero?("not-exist-test-target-file")
+
+  fp1 = File.open($mrbtest_io_rfname)
+  fp2 = File.open($mrbtest_io_wfname)
+  assert_equal false, FileTest.zero?(fp1)
+  assert_equal true,  FileTest.zero?(fp2)
+  fp1.close
+  fp2.close
+
+  assert_raise IOError do
+    FileTest.zero?(fp1)
+  end
+  assert_raise IOError do
+    FileTest.zero?(fp2)
+  end
+
+  fp1.closed? && fp2.closed?
+end
+
+assert('FileTest TEST CLEANUP') do
+  assert_nil MRubyIOTestUtil.io_test_cleanup
+end
diff --git a/test/io.rb b/test/io.rb
new file mode 100644
index 000000000..727c67303
--- /dev/null
+++ b/test/io.rb
@@ -0,0 +1,237 @@
+##
+# IO Test
+
+assert('IO', '15.2.20') do
+  assert_equal(Class, IO.class)
+end
+
+assert('IO', '15.2.20.2') do
+  assert_equal(Object, IO.superclass)
+end
+
+assert('IO', '15.2.20.3') do
+  assert_include(IO.included_modules, Enumerable)
+end
+
+assert('IO.new') do
+  IO.new(0)
+end
+
+assert('IO gc check') do
+  100.times { IO.new(0) }
+end
+
+assert('IO TEST SETUP') do
+  MRubyIOTestUtil.io_test_setup
+end
+
+assert('IO.sysopen, IO#close, IO#closed?') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  assert_equal Fixnum, fd.class
+  io = IO.new fd
+  assert_equal IO, io.class
+  assert_equal false, io.closed?, "IO not closed"
+  assert_equal nil,   io.close,   "IO#close should return nil"
+  assert_equal true,  io.closed?, "IO#closed? should return true"
+end
+
+assert('IO.sysopen, IO#sysread') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  str1 = "     "
+  str2 = io.sysread(5, str1)
+  assert_equal $mrbtest_io_msg[0,5], str1
+  assert_equal $mrbtest_io_msg[0,5], str2
+  assert_raise EOFError do
+    io.sysread(10000)
+    io.sysread(10000)
+  end
+  io.close
+  io.closed?
+end
+
+assert('IO.sysopen, IO#syswrite') do
+  fd = IO.sysopen $mrbtest_io_wfname, "w"
+  io = IO.new fd, "w"
+  str = "abcdefg"
+  len = io.syswrite(str)
+  assert_equal str.size, len
+  io.close
+  io.closed?
+end
+
+assert('IO#_read_buf') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  def io._buf
+    @buf
+  end
+  msg_len = $mrbtest_io_msg.size + 1
+  assert_equal '', io._buf
+  assert_equal $mrbtest_io_msg + "\n", io._read_buf
+  assert_equal $mrbtest_io_msg + "\n", io._buf
+  assert_equal 'mruby', io.read(5)
+  assert_equal 5, io.pos
+  assert_equal msg_len - 5, io._buf.size
+  assert_equal $mrbtest_io_msg[5,100] + "\n", io.read
+  assert_equal 0, io._buf.size
+  assert_raise EOFError do
+    io._read_buf
+  end
+  assert_equal true, io.eof
+  assert_equal true, io.eof?
+  io.close
+  io.closed?
+end
+
+assert('IO#read argument check') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  assert_raise TypeError do
+    io.read("str")
+  end
+  assert_raise ArgumentError do
+    io.read(-5)
+  end
+  io.close
+  io.closed?
+end
+
+assert('IO#read') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  assert_equal 'mruby', io.read(5)
+  assert_equal $mrbtest_io_msg[5,100] + "\n", io.read
+  assert_equal nil,  io.read
+  io.close
+  io.closed?
+end
+
+assert('IO#readchar, IO#getc') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  def io._buf
+    @buf
+  end
+  assert_equal 'm', io.readchar
+  assert_equal 1, io.pos
+  assert_equal 'r', io.getc
+  assert_equal 2, io.pos
+  io.gets
+  assert_raise EOFError do
+    io.readchar
+  end
+  assert_equal nil, io.getc
+  io.close
+  io.closed?
+end
+
+assert('IO#pos=, IO#seek') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  def io._buf
+    @buf
+  end
+  assert_equal 'm', io.getc
+  assert_equal 1, io.pos
+  assert_equal 0, io.seek(0)
+  assert_equal 0, io.pos
+  io.close
+  io.closed?
+end
+
+
+assert('IO#gets') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+
+  # gets without arguments
+  assert_equal $mrbtest_io_msg + "\n", io.gets, "gets without arguments"
+  assert_equal nil, io.gets, "gets returns nil, when EOF"
+
+  # gets with limit
+  io.pos = 0
+  assert_equal $mrbtest_io_msg[0, 5], io.gets(5), "gets with limit"
+
+  # gets with rs
+  io.pos = 0
+  assert_equal $mrbtest_io_msg[0, 6], io.gets(' '), "gets with rs"
+
+  # gets with rs, limit
+  io.pos = 0
+  assert_equal $mrbtest_io_msg[0, 5], io.gets(' ', 5), "gets with rs, limit"
+  io.close
+  assert_equal true, io.closed?, "close success"
+
+  # reading many-lines file.
+  fd = IO.sysopen $mrbtest_io_wfname, "w"
+  io = IO.new fd, "w"
+  io.write "0123456789" * 2 + "\na"
+  assert_equal 22, io.pos
+  io.close
+  assert_equal true, io.closed?
+
+  fd = IO.sysopen $mrbtest_io_wfname
+  io = IO.new fd
+  line = io.gets
+
+  # gets first line
+  assert_equal "0123456789" * 2 + "\n", line, "gets first line"
+  assert_equal 21, line.size
+  assert_equal 21, io.pos
+
+  # gets second line
+  assert_equal "a", io.gets, "gets second line"
+
+  # gets third line
+  assert_equal nil, io.gets, "gets third line; returns nil"
+
+  io.close
+  io.closed?
+end
+
+assert('IO#gets - paragraph mode') do
+  fd = IO.sysopen $mrbtest_io_wfname, "w"
+  io = IO.new fd, "w"
+  io.write "0" * 10 + "\n"
+  io.write "1" * 10 + "\n\n"
+  io.write "2" * 10 + "\n"
+  assert_equal 34, io.pos
+  io.close
+  assert_equal true, io.closed?
+
+  fd = IO.sysopen $mrbtest_io_wfname
+  io = IO.new fd
+  para1 = "#{'0' * 10}\n#{'1' * 10}\n\n"
+  text1 = io.gets("")
+  assert_equal para1, text1
+  para2 = "#{'2' * 10}\n"
+  text2 = io.gets("")
+  assert_equal para2, text2
+  io.close
+  io.closed?
+end
+
+assert('IO.popen') do
+  io = IO.popen("ls")
+  assert_equal Fixnum, io.pid.class
+  ls = io.read
+  assert_equal ls.class, String
+  assert_include ls, 'AUTHORS'
+  assert_include ls, 'mrblib'
+  io.close
+  io.closed?
+end
+
+assert('IO#fileno') do
+  fd = IO.sysopen $mrbtest_io_rfname
+  io = IO.new fd
+  assert_equal io.fileno, fd
+  assert_equal io.to_i, fd
+  io.close
+  io.closed?
+end
+
+assert('IO TEST CLEANUP') do
+  assert_nil MRubyIOTestUtil.io_test_cleanup
+end
diff --git a/test/mruby_io_test.c b/test/mruby_io_test.c
new file mode 100644
index 000000000..71ef715a5
--- /dev/null
+++ b/test/mruby_io_test.c
@@ -0,0 +1,94 @@
+#include "mruby.h"
+#include "mruby/array.h"
+#include "mruby/string.h"
+#include "mruby/variable.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static mrb_value
+mrb_io_test_io_setup(mrb_state *mrb, mrb_value self)
+{
+  char rfname[] = "tmp.XXXXXXXX";
+  char wfname[] = "tmp.XXXXXXXX";
+  char msg[] = "mruby io test";
+  FILE *fp;
+  mrb_value ary = mrb_ary_new(mrb);
+
+  mktemp(rfname);
+  mktemp(wfname);
+  mrb_gv_set(mrb, mrb_intern(mrb, "$mrbtest_io_rfname"), mrb_str_new_cstr(mrb, rfname));
+  mrb_gv_set(mrb, mrb_intern(mrb, "$mrbtest_io_wfname"), mrb_str_new_cstr(mrb, wfname));
+  mrb_gv_set(mrb, mrb_intern(mrb, "$mrbtest_io_msg"), mrb_str_new_cstr(mrb, msg));
+
+  mrb_ary_push(mrb, ary, mrb_str_new_cstr(mrb, rfname));
+  mrb_ary_push(mrb, ary, mrb_str_new_cstr(mrb, wfname));
+  mrb_ary_push(mrb, ary, mrb_str_new_cstr(mrb, msg));
+
+  fp = fopen(rfname, "w");
+  if (fp == NULL) {
+    mrb_raise(mrb, E_RUNTIME_ERROR, "can't open temporary file");
+    return mrb_nil_value();
+  }
+  fprintf(fp, "%s\n", msg);
+  fclose(fp);
+
+  fp = fopen(wfname, "w");
+  if (fp == NULL) {
+    mrb_raise(mrb, E_RUNTIME_ERROR, "can't open temporary file");
+    return mrb_nil_value();
+  }
+  fclose(fp);
+
+  return ary;
+}
+
+static mrb_value
+mrb_io_test_io_cleanup(mrb_state *mrb, mrb_value self)
+{
+  mrb_value rfname = mrb_gv_get(mrb, mrb_intern(mrb, "$mrbtest_io_rfname"));
+  mrb_value wfname = mrb_gv_get(mrb, mrb_intern(mrb, "$mrbtest_io_wfname"));
+
+  if (mrb_type(rfname) == MRB_TT_STRING) {
+    remove(RSTRING_PTR(rfname));
+  }
+  if (mrb_type(wfname) == MRB_TT_STRING) {
+    remove(RSTRING_PTR(wfname));
+  }
+
+  mrb_gv_set(mrb, mrb_intern(mrb, "$mrbtest_io_rfname"), mrb_nil_value());
+  mrb_gv_set(mrb, mrb_intern(mrb, "$mrbtest_io_wfname"), mrb_nil_value());
+  mrb_gv_set(mrb, mrb_intern(mrb, "$mrbtest_io_msg"), mrb_nil_value());
+
+  return mrb_nil_value();
+}
+
+static mrb_value
+mrb_io_test_file_setup(mrb_state *mrb, mrb_value self)
+{
+  mrb_value ary = mrb_io_test_io_setup(mrb, self);
+  symlink("/usr/bin", "test-bin");
+
+  return ary;
+}
+
+static mrb_value
+mrb_io_test_file_cleanup(mrb_state *mrb, mrb_value self)
+{
+  mrb_io_test_io_cleanup(mrb, self);
+  remove("test-bin");
+
+  return mrb_nil_value();
+}
+
+void
+mrb_mruby_io_gem_test(mrb_state* mrb)
+{
+  struct RClass *io_test = mrb_define_module(mrb, "MRubyIOTestUtil");
+  mrb_define_class_method(mrb, io_test, "io_test_setup", mrb_io_test_io_setup, ARGS_NONE());
+  mrb_define_class_method(mrb, io_test, "io_test_cleanup", mrb_io_test_io_cleanup, ARGS_NONE());
+
+  mrb_define_class_method(mrb, io_test, "file_test_setup", mrb_io_test_file_setup, ARGS_NONE());
+  mrb_define_class_method(mrb, io_test, "file_test_cleanup", mrb_io_test_file_cleanup, ARGS_NONE());
+
+}