add IO.read

README.md

@@ -18,7 +18,7 @@ IO, File module for mruby
 | IO.foreach                 |          |      |
 | IO.pipe                    |          |      |
 | IO.popen                   |    o     |      |
-| IO.read                    |          |      |
+| IO.read                    |    o     |      |
 | IO.readlines               |          |      |
 | IO.select                  |          |      |
 | IO.sysopen                 |    o     |      |

mrblib/io.rb

@@ -41,6 +41,54 @@ class IO
     end
   end
 
+
+  def self.read(path, length=nil, offset=nil, opt=nil)
+    if not opt.nil?        # 4 arguments
+      offset ||= 0
+    elsif not offset.nil?  # 3 arguments
+      if offset.is_a? Hash
+        opt = offset
+        offset = 0
+      else
+        opt = {}
+      end
+    elsif not length.nil?  # 2 arguments
+      if length.is_a? Hash
+        opt = length
+        offset = 0
+        length = nil
+      else
+        offset = 0
+        opt = {}
+      end
+    else                   # only 1 argument
+      opt = {}
+      offset = 0
+      length = nil
+    end
+
+    str = ""
+    fd = -1
+    io = nil
+    begin
+      if path[0] == "|"
+        io = IO.popen(path[1..-1], (opt[:mode] || "r"))
+      else
+        fd = IO.sysopen(path)
+        io = IO.open(fd, opt[:mode] || "r")
+      end
+      io.seek(offset) if offset > 0
+      str = io.read(length)
+    ensure
+      if io
+        io.close
+      elsif fd != -1
+        IO._sysclose(fd)
+      end
+    end
+    str
+  end
+
   def flush
     # mruby-io always writes immediately (no output buffer).
     self
@@ -130,7 +178,7 @@ class IO
       begin
         _read_buf
       rescue EOFError => e
-        str = nil  if str.empty?
+        str = nil if str.empty? and (not length.nil?) and length != 0
         break
       end
 

src/io.c

@@ -3,7 +3,6 @@
 */
 
 #include "mruby.h"
-
 #include "mruby/hash.h"
 #include "mruby/data.h"
 #include "mruby/khash.h"
@@ -372,6 +371,17 @@ mrb_io_s_for_fd(mrb_state *mrb, mrb_value klass)
   return mrb_io_initialize(mrb, io);
 }
 
+mrb_value
+mrb_io_s_sysclose(mrb_state *mrb, mrb_value klass)
+{
+  mrb_int fd;
+  mrb_get_args(mrb, "i", &fd);
+  if (close(fd) == -1) {
+    mrb_sys_fail(mrb, "close");
+  }
+  return mrb_fixnum_value(0);
+}
+
 mrb_value
 mrb_io_s_sysopen(mrb_state *mrb, mrb_value klass)
 {
@@ -741,9 +751,10 @@ mrb_init_io(mrb_state *mrb)
   mrb_include_module(mrb, io, mrb_module_get(mrb, "Enumerable")); /* 15.2.20.3 */
 
   mrb_define_class_method(mrb, io, "_popen",  mrb_io_s_popen,   MRB_ARGS_ANY());
+  mrb_define_class_method(mrb, io, "_sysclose",  mrb_io_s_sysclose, MRB_ARGS_REQ(1));
   mrb_define_class_method(mrb, io, "for_fd",  mrb_io_s_for_fd,  MRB_ARGS_REQ(1)|MRB_ARGS_OPT(2));
-  mrb_define_class_method(mrb, io, "sysopen", mrb_io_s_sysopen, MRB_ARGS_ANY());
   mrb_define_class_method(mrb, io, "select",  mrb_io_s_select,  MRB_ARGS_ANY());
+  mrb_define_class_method(mrb, io, "sysopen", mrb_io_s_sysopen, MRB_ARGS_ANY());
 
   mrb_define_method(mrb, io, "initialize", mrb_io_initialize, MRB_ARGS_ANY());    /* 15.2.20.5.21 (x)*/
   mrb_define_method(mrb, io, "sysread",    mrb_io_sysread,    MRB_ARGS_ANY());

test/io.rb

@@ -130,7 +130,7 @@ assert('IO#read') do
   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
+  assert_equal "", io.read
   io.close
   io.closed?
 end
@@ -251,6 +251,29 @@ assert('IO.popen') do
   io.closed?
 end
 
+assert('IO.read') do
+  # empty file
+  fd = IO.sysopen $mrbtest_io_wfname, "w"
+  io = IO.new fd, "w"
+  io.close
+  assert_equal "",  IO.read($mrbtest_io_wfname)
+  assert_equal nil, IO.read($mrbtest_io_wfname, 1)
+
+  # one byte file
+  fd = IO.sysopen $mrbtest_io_wfname, "w"
+  io = IO.new fd, "w"
+  io.write "123"
+  io.close
+  assert_equal "123", IO.read($mrbtest_io_wfname)
+  assert_equal "",    IO.read($mrbtest_io_wfname, 0)
+  assert_equal "1",   IO.read($mrbtest_io_wfname, 1)
+  assert_equal "",    IO.read($mrbtest_io_wfname, 0, 10)
+  assert_equal "23",  IO.read($mrbtest_io_wfname, 2, 1)
+  assert_equal "23",  IO.read($mrbtest_io_wfname, 10, 1)
+  assert_equal "",    IO.read($mrbtest_io_wfname, nil, 10)
+  assert_equal nil,   IO.read($mrbtest_io_wfname, 1, 10)
+end
+
 assert('IO#fileno') do
   fd = IO.sysopen $mrbtest_io_rfname
   io = IO.new fd