support buflen=-1 and readall like FileIO does

required to make pytest work with an active eventlet.monkey_patch() on py3

https://github.com/eventlet/eventlet/pull/239

eventlet/greenio/py3.py

@@ -75,10 +75,26 @@ class GreenFileIO(_OriginalIOBase):
     def fileno(self):
         return self._fileno
 
-    def read(self, buflen):
+    def read(self, size=-1):
+        if size == -1:
+            return self.readall()
+
         while True:
             try:
-                return _original_os.read(self._fileno, buflen)
+                return _original_os.read(self._fileno, size)
+            except OSError as e:
+                if get_errno(e) not in SOCKET_BLOCKING:
+                    raise IOError(*e.args)
+            self._trampoline(self, read=True)
+
+    def readall(self):
+        buf = []
+        while True:
+            try:
+                chunk = _original_os.read(self._fileno, DEFAULT_BUFFER_SIZE)
+                if chunk == b'':
+                    return b''.join(buf)
+                buf.append(chunk)
             except OSError as e:
                 if get_errno(e) not in SOCKET_BLOCKING:
                     raise IOError(*e.args)

tests/greenio_test.py

@@ -3,6 +3,7 @@ import errno
 import eventlet
 import fcntl
 import gc
+from io import DEFAULT_BUFFER_SIZE
 import os
 import shutil
 import socket as _orig_sock
@@ -711,6 +712,20 @@ class TestGreenPipe(tests.LimitedTestCase):
 
         gt.wait()
 
+    def test_pip_read_until_end(self):
+        # similar to test_pip_read above but reading until eof
+        r, w = os.pipe()
+
+        r = greenio.GreenPipe(r, 'rb')
+        w = greenio.GreenPipe(w, 'wb')
+
+        w.write(b'c' * DEFAULT_BUFFER_SIZE * 2)
+        w.close()
+
+        buf = r.read()  # no chunk size specified; read until end
+        self.assertEqual(len(buf), 2 * DEFAULT_BUFFER_SIZE)
+        self.assertEqual(buf[:3], b'ccc')
+
     def test_pipe_writes_large_messages(self):
         r, w = os.pipe()