Allow any buffer type to be written to SFTPFile

Fixes #967 #968

Rollup of earlier branches proposed as #969 and #970 with
additional fix inside sftp_client.

Includes new tests for SFTPFile usage.

Change against the 1.17 branch.

2 files changed, 32 insertions, 4 deletions

diff --git a/paramiko/sftp_client.py b/paramiko/sftp_client.py
index 12a9506f..06637ca2 100644
--- a/paramiko/sftp_client.py
+++ b/paramiko/sftp_client.py
@@ -28,7 +28,7 @@ from paramiko import util
 from paramiko.channel import Channel
 from paramiko.message import Message
 from paramiko.common import INFO, DEBUG, o777
-from paramiko.py3compat import bytestring, b, u, long, string_types, bytes_types
+from paramiko.py3compat import bytestring, b, u, long
 from paramiko.sftp import BaseSFTP, CMD_OPENDIR, CMD_HANDLE, SFTPError, CMD_READDIR, \
     CMD_NAME, CMD_CLOSE, SFTP_FLAG_READ, SFTP_FLAG_WRITE, SFTP_FLAG_CREATE, \
     SFTP_FLAG_TRUNC, SFTP_FLAG_APPEND, SFTP_FLAG_EXCL, CMD_OPEN, CMD_REMOVE, \
@@ -740,12 +740,10 @@ class SFTPClient(BaseSFTP, ClosingContextManager):
                     msg.add_int64(item)
                 elif isinstance(item, int):
                     msg.add_int(item)
-                elif isinstance(item, (string_types, bytes_types)):
-                    msg.add_string(item)
                 elif isinstance(item, SFTPAttributes):
                     item._pack(msg)
                 else:
-                    raise Exception('unknown type for %r type %r' % (item, type(item)))
+                    msg.add_string(item)
             num = self.request_number
             self._expecting[num] = fileobj
             self.request_number += 1
diff --git a/tests/test_sftp.py b/tests/test_sftp.py
index d3064fff..98a9cebb 100755
--- a/tests/test_sftp.py
+++ b/tests/test_sftp.py
@@ -35,6 +35,7 @@ from tempfile import mkstemp
 import paramiko
 from paramiko.py3compat import PY2, b, u, StringIO
 from paramiko.common import o777, o600, o666, o644
+from tests import skipUnlessBuiltin
 from tests.stub_sftp import StubServer, StubSFTPServer
 from tests.loop import LoopSocket
 from tests.util import test_path
@@ -817,6 +818,35 @@ class SFTPTest (unittest.TestCase):
         sftp_attributes = SFTPAttributes()
         self.assertEqual(str(sftp_attributes), "?---------   1 0        0               0 (unknown date) ?")
 
+    @skipUnlessBuiltin('buffer')
+    def test_write_buffer(self):
+        """Test write() using a buffer instance."""
+        data = 3 * b'A potentially large block of data to chunk up.\n'
+        try:
+            with sftp.open('%s/write_buffer' % FOLDER, 'wb') as f:
+                for offset in range(0, len(data), 8):
+                    f.write(buffer(data, offset, 8))
+
+            with sftp.open('%s/write_buffer' % FOLDER, 'rb') as f:
+                self.assertEqual(f.read(), data)
+        finally:
+            sftp.remove('%s/write_buffer' % FOLDER)
+
+    @skipUnlessBuiltin('memoryview')
+    def test_write_memoryview(self):
+        """Test write() using a memoryview instance."""
+        data = 3 * b'A potentially large block of data to chunk up.\n'
+        try:
+            with sftp.open('%s/write_memoryview' % FOLDER, 'wb') as f:
+                view = memoryview(data)
+                for offset in range(0, len(data), 8):
+                    f.write(view[offset:offset+8])
+
+            with sftp.open('%s/write_memoryview' % FOLDER, 'rb') as f:
+                self.assertEqual(f.read(), data)
+        finally:
+            sftp.remove('%s/write_memoryview' % FOLDER)
+
 
 if __name__ == '__main__':
     SFTPTest.init_loopback()