Implement `IO#pread` and `IO#pwrite`

It is available by default in environments where `__unix__` is defined.
Other environments are enabled by defining `MRB_WITH_IO_PREAD_PWRITE`
(requires an implementation of `pread()` and `pwrite()` functions).

In any case, you can disable it by defining
`MRB_WITHOUT_IO_PREAD_PWRITE`.

1 files changed, 28 insertions, 0 deletions

diff --git a/mrbgems/mruby-io/test/io.rb b/mrbgems/mruby-io/test/io.rb
index e3024cf9a..458d2cdc2 100644
--- a/mrbgems/mruby-io/test/io.rb
+++ b/mrbgems/mruby-io/test/io.rb
@@ -564,6 +564,34 @@ assert('IO#sysseek') do
   end
 end
 
+assert('IO#pread') do
+  skip "IO#pread is not implemented on this configuration" unless MRubyIOTestUtil::MRB_WITH_IO_PREAD_PWRITE
+
+  IO.open(IO.sysopen($mrbtest_io_rfname, 'r'), 'r') do |io|
+    assert_equal $mrbtest_io_msg.byteslice(5, 8), io.pread(8, 5)
+    assert_equal 0, io.pos
+    assert_equal $mrbtest_io_msg.byteslice(1, 5), io.pread(5, 1)
+    assert_equal 0, io.pos
+    assert_raise(RuntimeError) { io.pread(20, -9) }
+  end
+end
+
+assert('IO#pwrite') do
+  skip "IO#pwrite is not implemented on this configuration" unless MRubyIOTestUtil::MRB_WITH_IO_PREAD_PWRITE
+
+  IO.open(IO.sysopen($mrbtest_io_wfname, 'w+'), 'w+') do |io|
+    assert_equal 6, io.pwrite("Warld!", 7)
+    assert_equal 0, io.pos
+    assert_equal 7, io.pwrite("Hello, ", 0)
+    assert_equal 0, io.pos
+    assert_equal "Hello, Warld!", io.read
+    assert_equal 6, io.pwrite("world!", 7)
+    assert_equal 13, io.pos
+    io.pos = 0
+    assert_equal "Hello, world!", io.read
+  end
+end
+
 assert('IO.pipe') do
   begin
     called = false