[pypy-commit] cffi default: Issue #394
arigo
pypy.commits at gmail.com
Sun Dec 16 02:48:57 EST 2018
Author: Armin Rigo <arigo at tunes.org>
Branch:
Changeset: r3175:f4de3d6b3c34
Date: 2018-12-16 08:48 +0100
http://bitbucket.org/cffi/cffi/changeset/f4de3d6b3c34/
Log: Issue #394
Implement ffi.from_buffer(x, require_writable=True)
diff --git a/c/_cffi_backend.c b/c/_cffi_backend.c
--- a/c/_cffi_backend.c
+++ b/c/_cffi_backend.c
@@ -6741,7 +6741,8 @@
return 0;
}
-static PyObject *direct_from_buffer(CTypeDescrObject *ct, PyObject *x)
+static PyObject *direct_from_buffer(CTypeDescrObject *ct, PyObject *x,
+ int require_writable)
{
CDataObject *cd;
Py_buffer *view;
@@ -6761,7 +6762,7 @@
PyErr_NoMemory();
return NULL;
}
- if (_my_PyObject_GetContiguousBuffer(x, view, 0) < 0)
+ if (_my_PyObject_GetContiguousBuffer(x, view, require_writable) < 0)
goto error1;
cd = (CDataObject *)PyObject_GC_New(CDataObject_owngc_frombuf,
@@ -6789,15 +6790,17 @@
{
CTypeDescrObject *ct;
PyObject *x;
-
- if (!PyArg_ParseTuple(args, "O!O", &CTypeDescr_Type, &ct, &x))
+ int require_writable = 0;
+
+ if (!PyArg_ParseTuple(args, "O!O|i", &CTypeDescr_Type, &ct, &x,
+ &require_writable))
return NULL;
if (!(ct->ct_flags & CT_IS_UNSIZED_CHAR_A)) {
PyErr_Format(PyExc_TypeError, "needs 'char[]', got '%s'", ct->ct_name);
return NULL;
}
- return direct_from_buffer(ct, x);
+ return direct_from_buffer(ct, x, require_writable);
}
static int _fetch_as_buffer(PyObject *x, Py_buffer *view, int writable_only)
diff --git a/c/ffi_obj.c b/c/ffi_obj.c
--- a/c/ffi_obj.c
+++ b/c/ffi_obj.c
@@ -697,9 +697,16 @@
"containing large quantities of raw data in some other format, like\n"
"'array.array' or numpy arrays.");
-static PyObject *ffi_from_buffer(PyObject *self, PyObject *arg)
+static PyObject *ffi_from_buffer(PyObject *self, PyObject *args, PyObject *kwds)
{
- return direct_from_buffer(g_ct_chararray, arg);
+ PyObject *arg;
+ int require_writable = 0;
+ static char *keywords[] = {"python_buffer", "require_writable", NULL};
+
+ if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|i:from_buffer", keywords,
+ &arg, &require_writable))
+ return NULL;
+ return direct_from_buffer(g_ct_chararray, arg, require_writable);
}
PyDoc_STRVAR(ffi_gc_doc,
@@ -1072,7 +1079,7 @@
{"cast", (PyCFunction)ffi_cast, METH_VARARGS, ffi_cast_doc},
{"dlclose", (PyCFunction)ffi_dlclose, METH_VARARGS, ffi_dlclose_doc},
{"dlopen", (PyCFunction)ffi_dlopen, METH_VARARGS, ffi_dlopen_doc},
- {"from_buffer",(PyCFunction)ffi_from_buffer,METH_O, ffi_from_buffer_doc},
+ {"from_buffer",(PyCFunction)ffi_from_buffer,METH_VKW, ffi_from_buffer_doc},
{"from_handle",(PyCFunction)ffi_from_handle,METH_O, ffi_from_handle_doc},
{"gc", (PyCFunction)ffi_gc, METH_VKW, ffi_gc_doc},
{"getctype", (PyCFunction)ffi_getctype, METH_VKW, ffi_getctype_doc},
diff --git a/c/test_c.py b/c/test_c.py
--- a/c/test_c.py
+++ b/c/test_c.py
@@ -3741,6 +3741,18 @@
check(4 | 8, "CHB", "GTB")
check(4 | 16, "CHB", "ROB")
+def test_from_buffer_require_writable():
+ BChar = new_primitive_type("char")
+ BCharP = new_pointer_type(BChar)
+ BCharA = new_array_type(BCharP, None)
+ p1 = from_buffer(BCharA, b"foo", False)
+ assert p1 == from_buffer(BCharA, b"foo", False)
+ py.test.raises((TypeError, BufferError), from_buffer, BCharA, b"foo", True)
+ ba = bytearray(b"foo")
+ p1 = from_buffer(BCharA, ba, True)
+ p1[0] = b"g"
+ assert ba == b"goo"
+
def test_memmove():
Short = new_primitive_type("short")
ShortA = new_array_type(new_pointer_type(Short), None)
diff --git a/cffi/api.py b/cffi/api.py
--- a/cffi/api.py
+++ b/cffi/api.py
@@ -341,7 +341,7 @@
# """
# note that 'buffer' is a type, set on this instance by __init__
- def from_buffer(self, python_buffer):
+ def from_buffer(self, python_buffer, require_writable=False):
"""Return a <cdata 'char[]'> that points to the data of the
given Python object, which must support the buffer interface.
Note that this is not meant to be used on the built-in types
@@ -349,7 +349,8 @@
but only on objects containing large quantities of raw data
in some other format, like 'array.array' or numpy arrays.
"""
- return self._backend.from_buffer(self.BCharA, python_buffer)
+ return self._backend.from_buffer(self.BCharA, python_buffer,
+ require_writable)
def memmove(self, dest, src, n):
"""ffi.memmove(dest, src, n) copies n bytes of memory from src to dest.
diff --git a/doc/source/ref.rst b/doc/source/ref.rst
--- a/doc/source/ref.rst
+++ b/doc/source/ref.rst
@@ -188,7 +188,8 @@
*New in version 1.10:* ``ffi.buffer`` is now the type of the returned
buffer objects; ``ffi.buffer()`` actually calls the constructor.
-**ffi.from_buffer(python_buffer)**: return a ``<cdata 'char[]'>`` that
+**ffi.from_buffer(python_buffer, require_writable=False)**:
+return a ``<cdata 'char[]'>`` that
points to the data of the given Python object, which must support the
buffer interface. This is the opposite of ``ffi.buffer()``. It gives
a reference to the existing data, not a copy.
@@ -216,6 +217,18 @@
resize the bytearray, the ``<cdata>`` object will point to freed
memory); and byte strings were supported in version 1.8 onwards.
+*New in version 1.12:* added the ``require_writable`` argument. If set to
+True, the function fails if the buffer obtained from ``python_buffer`` is
+read-only (e.g. if ``python_buffer`` is a byte string). The exact exception is
+raised by the object itself, and for things like bytes it varies with the
+Python version, so don't rely on it. (Before version 1.12, the same effect can
+be achieved with a hack: call ``ffi.memmove(python_buffer, b"", 0)``. This has
+no effect if the object is writable, but fails if it is read-only.)
+
+Please keep in mind that CFFI does not implement the C keyword ``const``: even
+if you set ``require_writable`` to False explicitly, you still get a regular
+read-write cdata pointer.
+
ffi.memmove()
+++++++++++++
diff --git a/doc/source/whatsnew.rst b/doc/source/whatsnew.rst
--- a/doc/source/whatsnew.rst
+++ b/doc/source/whatsnew.rst
@@ -23,6 +23,10 @@
* CPython 2.x: ``ffi.dlopen()`` failed with non-ascii file names on Posix
+* ``ffi.from_buffer()`` takes a new keyword argument ``require_writable``.
+ When set to True, it asks the object passed in to raise an exception if
+ it is read-only.
+
v1.11.5
=======
diff --git a/testing/cffi0/test_ffi_backend.py b/testing/cffi0/test_ffi_backend.py
--- a/testing/cffi0/test_ffi_backend.py
+++ b/testing/cffi0/test_ffi_backend.py
@@ -326,6 +326,16 @@
assert ffi.typeof(c) is ffi.typeof("char[]")
ffi.cast("unsigned short *", c)[1] += 500
assert list(a) == [10000, 20500, 30000]
+ assert c == ffi.from_buffer(a, True)
+ assert c == ffi.from_buffer(a, require_writable=True)
+ #
+ p = ffi.from_buffer(b"abcd")
+ assert p[2] == b"c"
+ #
+ assert p == ffi.from_buffer(b"abcd", False)
+ py.test.raises((TypeError, BufferError), ffi.from_buffer, b"abcd", True)
+ py.test.raises((TypeError, BufferError), ffi.from_buffer, b"abcd",
+ require_writable=True)
def test_memmove(self):
ffi = FFI()
diff --git a/testing/cffi1/test_ffi_obj.py b/testing/cffi1/test_ffi_obj.py
--- a/testing/cffi1/test_ffi_obj.py
+++ b/testing/cffi1/test_ffi_obj.py
@@ -243,6 +243,16 @@
assert ffi.typeof(c) is ffi.typeof("char[]")
ffi.cast("unsigned short *", c)[1] += 500
assert list(a) == [10000, 20500, 30000]
+ assert c == ffi.from_buffer(a, True)
+ assert c == ffi.from_buffer(a, require_writable=True)
+ #
+ p = ffi.from_buffer(b"abcd")
+ assert p[2] == b"c"
+ #
+ assert p == ffi.from_buffer(b"abcd", False)
+ py.test.raises((TypeError, BufferError), ffi.from_buffer, b"abcd", True)
+ py.test.raises((TypeError, BufferError), ffi.from_buffer, b"abcd",
+ require_writable=True)
def test_memmove():
ffi = _cffi1_backend.FFI()
diff --git a/testing/cffi1/test_new_ffi_1.py b/testing/cffi1/test_new_ffi_1.py
--- a/testing/cffi1/test_new_ffi_1.py
+++ b/testing/cffi1/test_new_ffi_1.py
@@ -1653,6 +1653,16 @@
assert ffi.typeof(c) is ffi.typeof("char[]")
ffi.cast("unsigned short *", c)[1] += 500
assert list(a) == [10000, 20500, 30000]
+ assert c == ffi.from_buffer(a, True)
+ assert c == ffi.from_buffer(a, require_writable=True)
+ #
+ p = ffi.from_buffer(b"abcd")
+ assert p[2] == b"c"
+ #
+ assert p == ffi.from_buffer(b"abcd", False)
+ py.test.raises((TypeError, BufferError), ffi.from_buffer, b"abcd", True)
+ py.test.raises((TypeError, BufferError), ffi.from_buffer, b"abcd",
+ require_writable=True)
def test_all_primitives(self):
assert set(PRIMITIVE_TO_INDEX) == set([
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