python: Wrap objects implementing the buffer protocol.

* lang/python/Makefile.am: Add the toplevel source directory to CFLAGS
when compiling the bindings so that we can use private header files.
* lang/python/gpgme.i (gpgme_data_t): Rework the object wrapping.  Do
not create a Python wrapper object, merely a gpgme_data_t object, and
keep references to buffer objects, if any.  If necessary, update the
buffer after the function call.
(pygpgme_wrap_gpgme_data_t): New function.
* lang/python/helpers.c (object_to_gpgme_data_t): Rework object
wrapping.  Also wrap objects implementing the buffer protocol.
* lang/python/helpers.h (object_to_gpgme_data_t): Update prototype.
(pygpgme_wrap_gpgme_data_t): New prototype.
* lang/python/tests/t-idiomatic.py: Demonstrate this.

Signed-off-by: Justus Winter <[email protected]>

1 files changed, 27 insertions, 8 deletions

diff --git a/lang/python/tests/t-idiomatic.py b/lang/python/tests/t-idiomatic.py
index 37cfb64a..b2526902 100755
--- a/lang/python/tests/t-idiomatic.py
+++ b/lang/python/tests/t-idiomatic.py
@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU Lesser General Public
 # License along with this program; if not, see <http://www.gnu.org/licenses/>.
 
+import io
 import os
 import tempfile
 from pyme import core, constants, errors
@@ -33,14 +34,7 @@ with core.Context() as c, core.Data() as d:
 assert leak_c.wrapped == None
 assert leak_d.wrapped == None
 
-# Demonstrate automatic wrapping of file-like objects with 'fileno'
-# method.
-with tempfile.TemporaryFile() as source, \
-     tempfile.TemporaryFile() as signed, \
-     tempfile.TemporaryFile() as sink:
-    source.write(b"Hallo Leute\n")
-    source.seek(0, os.SEEK_SET)
-
+def sign_and_verify(source, signed, sink):
     with core.Context() as c:
         c.op_sign(source, signed, constants.SIG_MODE_NORMAL)
         signed.seek(0, os.SEEK_SET)
@@ -54,3 +48,28 @@ with tempfile.TemporaryFile() as source, \
 
     sink.seek(0, os.SEEK_SET)
     assert sink.read() == b"Hallo Leute\n"
+
+# Demonstrate automatic wrapping of file-like objects with 'fileno'
+# method.
+with tempfile.TemporaryFile() as source, \
+     tempfile.TemporaryFile() as signed, \
+     tempfile.TemporaryFile() as sink:
+    source.write(b"Hallo Leute\n")
+    source.seek(0, os.SEEK_SET)
+
+    sign_and_verify(source, signed, sink)
+
+# XXX: Python's io.BytesIo.truncate does not work as advertised.
+# http://bugs.python.org/issue27261
+bio = io.BytesIO()
+bio.truncate(1)
+if len(bio.getvalue()) != 1:
+    # This version of Python is affected, preallocate buffer.
+    preallocate = 128*b'\x00'
+else:
+    preallocate = b''
+
+# Demonstrate automatic wrapping of objects implementing the buffer
+# interface, and the use of data objects with the 'with' statement.
+with io.BytesIO(preallocate) as signed, core.Data() as sink:
+    sign_and_verify(b"Hallo Leute\n", signed, sink)