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python: Wrap objects implementing the buffer protocol.

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* 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 <justus@g10code.com>
This commit is contained in:
Justus Winter 2016-06-08 17:56:33 +02:00
parent 5464060bae
commit 616929b6ed
5 changed files with 180 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lang/python/Makefile.am
View File

@ -45,7 +45,7 @@ gpgme_wrap.c pyme/pygpgme.py: gpgme.i errors.i gpgme.h copystamp
$<
all-local: gpgme_wrap.c pyme/pygpgme.py copystamp
CFLAGS="$(CFLAGS)" \
CFLAGS="$(CFLAGS) -I$(top_srcdir)" \
$(PYTHON) setup.py build --verbose
clean-local:

98
lang/python/gpgme.i
View File

@ -114,17 +114,19 @@
}
// Special handling for references to our objects.
%typemap(in) gpgme_data_t DATAIN (PyObject *wrapper) {
%typemap(in) gpgme_data_t DATAIN (gpgme_data_t wrapper = NULL,
PyObject *bytesio = NULL, Py_buffer view) {
/* If we create a temporary wrapper object, we will store it in
wrapperN, where N is $argnum. Here in this fragment, SWIG will
automatically append $argnum. */
wrapper = NULL;
memset(&view, 0, sizeof view);
if ($input == Py_None)
$1 = NULL;
else {
PyObject *pypointer = NULL;
if((pypointer=object_to_gpgme_data_t($input, $argnum, &wrapper)) == NULL)
PyObject *pypointer;
pypointer = object_to_gpgme_data_t($input, $argnum, &wrapper,
&bytesio, &view);
if (pypointer == NULL)
return NULL;
/* input = $input, 1 = $1, 1_descriptor = $1_descriptor */
@ -141,8 +143,79 @@
}
%typemap(freearg) gpgme_data_t DATAIN {
/* See whether we need to update the Python buffer. */
if (resultobj && wrapper$argnum && view$argnum.buf
&& wrapper$argnum->data.mem.buffer != NULL)
{
/* The buffer is dirty. */
if (view$argnum.readonly)
{
Py_XDECREF(resultobj);
resultobj = NULL;
PyErr_SetString(PyExc_ValueError, "cannot update read-only buffer");
}
/* See if we need to truncate the buffer. */
if (resultobj && view$argnum.len != wrapper$argnum->data.mem.length)
{
if (bytesio$argnum == NULL)
{
Py_XDECREF(resultobj);
resultobj = NULL;
PyErr_SetString(PyExc_ValueError, "cannot resize buffer");
}
else
{
PyObject *retval;
PyBuffer_Release(&view$argnum);
retval = PyObject_CallMethod(bytesio$argnum, "truncate", "l",
(long)
wrapper$argnum->data.mem.length);
if (retval == NULL)
{
Py_XDECREF(resultobj);
resultobj = NULL;
}
else
{
Py_DECREF(retval);
retval = PyObject_CallMethod(bytesio$argnum, "getbuffer", NULL);
if (retval == NULL
|| PyObject_GetBuffer(retval, &view$argnum,
PyBUF_SIMPLE|PyBUF_WRITABLE) < 0)
{
Py_XDECREF(resultobj);
resultobj = NULL;
}
Py_XDECREF(retval);
if (resultobj && view$argnum.len
!= wrapper$argnum->data.mem.length)
{
Py_XDECREF(resultobj);
resultobj = NULL;
PyErr_Format(PyExc_ValueError,
"Expected buffer of length %zu, got %zi",
wrapper$argnum->data.mem.length,
view$argnum.len);
}
}
}
}
if (resultobj)
memcpy(view$argnum.buf, wrapper$argnum->data.mem.buffer,
wrapper$argnum->data.mem.length);
}
/* Free the temporary wrapper, if any. */
Py_XDECREF(wrapper$argnum);
if (wrapper$argnum)
gpgme_data_release(wrapper$argnum);
Py_XDECREF (bytesio$argnum);
if (wrapper$argnum && view$argnum.buf)
PyBuffer_Release(&view$argnum);
}
%apply gpgme_data_t DATAIN {gpgme_data_t plain, gpgme_data_t cipher,
@ -240,7 +313,10 @@
version for SWIG. We do, however, want to hide certain fields on
some structs, which we provide prior to including the version for
SWIG. */
%{ #include <gpgme.h> %}
%{
#include <gpgme.h>
#include "src/data.h" /* For struct gpgme_data. */
%}
/* This is for notations, where we want to hide the length fields, and
the unused bit field block. */
@ -291,5 +367,13 @@ FILE *fdopen(int fildes, const char *mode);
%{
#include "helpers.h"
/* SWIG support for helpers.c */
PyObject *
pygpgme_wrap_gpgme_data_t(gpgme_data_t data)
{
return SWIG_NewPointerObj(data, SWIGTYPE_p_gpgme_data, 0);
}
%}
%include "helpers.h"

102
lang/python/helpers.c
View File

@ -206,64 +206,72 @@ object_to_gpgme_t(PyObject *input, const char *objtype, int argnum)
objects with a fileno method, returning it in WRAPPER. This object
must be de-referenced when no longer needed. */
PyObject *
object_to_gpgme_data_t(PyObject *input, int argnum, PyObject **wrapper)
object_to_gpgme_data_t(PyObject *input, int argnum, gpgme_data_t *wrapper,
PyObject **bytesio, Py_buffer *view)
{
static PyObject *Data = NULL;
PyObject *data = input;
gpgme_error_t err;
PyObject *data;
PyObject *fd;
PyObject *result;
*wrapper = NULL;
if (Data == NULL) {
PyObject *core;
PyObject *from_list = PyList_New(0);
core = PyImport_ImportModuleLevel("core", PyEval_GetGlobals(),
PyEval_GetLocals(), from_list, 1);
Py_XDECREF(from_list);
if (core) {
Data = PyDict_GetItemString(PyModule_GetDict(core), "Data");
Py_XINCREF(Data);
}
else
return NULL;
}
/* See if it is a file-like object with file number. */
fd = PyObject_CallMethod(input, "fileno", NULL);
if (fd) {
/* File-like object with file number. */
PyObject *args = NULL;
PyObject *kw = NULL;
/* We don't need the fd, as we have no constructor accepting file
descriptors directly. */
err = gpgme_data_new_from_fd(wrapper, (int) PyLong_AsLong(fd));
Py_DECREF(fd);
if (err)
return pygpgme_raise_exception (err);
args = PyTuple_New(0);
kw = PyDict_New();
if (args == NULL || kw == NULL)
{
fail:
Py_XDECREF(args);
Py_XDECREF(kw);
return NULL;
}
if (PyDict_SetItemString(kw, "file", input) < 0)
goto fail;
*wrapper = PyObject_Call(Data, args, kw);
if (*wrapper == NULL)
goto fail;
Py_DECREF(args);
Py_DECREF(kw);
data = *wrapper;
return pygpgme_wrap_gpgme_data_t(*wrapper);
}
else
PyErr_Clear();
result = object_to_gpgme_t(data, "gpgme_data_t", argnum);
return result;
/* No? Maybe it implements the buffer protocol. */
data = PyObject_CallMethod(input, "getbuffer", NULL);
if (data)
{
/* Save a reference to input, which seems to be a BytesIO
object. */
Py_INCREF(input);
*bytesio = input;
}
else
{
PyErr_Clear();
/* No, but maybe the user supplied a buffer object? */
data = input;
}
/* Do we have a buffer object? */
if (PyObject_CheckBuffer(data))
{
if (PyObject_GetBuffer(data, view, PyBUF_SIMPLE) < 0)
return NULL;
if (data != input)
Py_DECREF(data);
assert (view->ndim == 1);
assert (view->shape == NULL);
assert (view->strides == NULL);
assert (view->suboffsets == NULL);
err = gpgme_data_new_from_mem(wrapper, view->buf, (size_t) view->len, 0);
if (err)
return pygpgme_raise_exception (err);
return pygpgme_wrap_gpgme_data_t(*wrapper);
}
/* As last resort we assume it is a wrapped data object. */
if (PyObject_HasAttrString(data, "_getctype"))
return object_to_gpgme_t(data, "gpgme_data_t", argnum);
return PyErr_Format(PyExc_TypeError,
"arg %d: expected pyme.Data, file, or an object "
"implementing the buffer protocol, got %s",
argnum, data->ob_type->tp_name);
}

7
lang/python/helpers.h
View File

@ -1,4 +1,5 @@
/*
# Copyright (C) 2016 g10 Code GmbH
# Copyright (C) 2004 Igor Belyi <belyi@users.sourceforge.net>
# Copyright (C) 2002 John Goerzen <jgoerzen@complete.org>
#
@ -30,7 +31,8 @@ gpgme_error_t pygpgme_exception2code(void);
PyObject *object_to_gpgme_t(PyObject *input, const char *objtype, int argnum);
PyObject *object_to_gpgme_data_t(PyObject *input, int argnum,
PyObject **wrapper);
gpgme_data_t *wrapper,
PyObject **bytesio, Py_buffer *view);
void pygpgme_clear_generic_cb(PyObject **cb);
PyObject *pygpgme_raise_callback_exception(PyObject *self);
@ -47,3 +49,6 @@ gpgme_error_t pyEditCb(void *opaque, gpgme_status_code_t status,
gpgme_error_t pygpgme_data_new_from_cbs(gpgme_data_t *r_data,
PyObject *pycbs,
PyObject **freelater);
/* SWIG support for helpers.c */
PyObject *pygpgme_wrap_gpgme_data_t(gpgme_data_t data);

35
lang/python/tests/t-idiomatic.py
View File

@ -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)