support for readonly buffers (#863) (#1466)
diff --git a/include/pybind11/buffer_info.h b/include/pybind11/buffer_info.h
index b106d2c..1f4115a 100644
--- a/include/pybind11/buffer_info.h
+++ b/include/pybind11/buffer_info.h
@@ -22,13 +22,14 @@
ssize_t ndim = 0; // Number of dimensions
std::vector<ssize_t> shape; // Shape of the tensor (1 entry per dimension)
std::vector<ssize_t> strides; // Number of bytes between adjacent entries (for each per dimension)
+ bool readonly = false; // flag to indicate if the underlying storage may be written to
buffer_info() { }
buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim,
- detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in)
+ detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, bool readonly=false)
: ptr(ptr), itemsize(itemsize), size(1), format(format), ndim(ndim),
- shape(std::move(shape_in)), strides(std::move(strides_in)) {
+ shape(std::move(shape_in)), strides(std::move(strides_in)), readonly(readonly) {
if (ndim != (ssize_t) shape.size() || ndim != (ssize_t) strides.size())
pybind11_fail("buffer_info: ndim doesn't match shape and/or strides length");
for (size_t i = 0; i < (size_t) ndim; ++i)
@@ -36,19 +37,23 @@
}
template <typename T>
- buffer_info(T *ptr, detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in)
- : buffer_info(private_ctr_tag(), ptr, sizeof(T), format_descriptor<T>::format(), static_cast<ssize_t>(shape_in->size()), std::move(shape_in), std::move(strides_in)) { }
+ buffer_info(T *ptr, detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, bool readonly=false)
+ : buffer_info(private_ctr_tag(), ptr, sizeof(T), format_descriptor<T>::format(), static_cast<ssize_t>(shape_in->size()), std::move(shape_in), std::move(strides_in), readonly) { }
- buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t size)
- : buffer_info(ptr, itemsize, format, 1, {size}, {itemsize}) { }
+ buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t size, bool readonly=false)
+ : buffer_info(ptr, itemsize, format, 1, {size}, {itemsize}, readonly) { }
template <typename T>
- buffer_info(T *ptr, ssize_t size)
- : buffer_info(ptr, sizeof(T), format_descriptor<T>::format(), size) { }
+ buffer_info(T *ptr, ssize_t size, bool readonly=false)
+ : buffer_info(ptr, sizeof(T), format_descriptor<T>::format(), size, readonly) { }
+
+ template <typename T>
+ buffer_info(const T *ptr, ssize_t size, bool readonly=true)
+ : buffer_info(const_cast<T*>(ptr), sizeof(T), format_descriptor<T>::format(), size, readonly) { }
explicit buffer_info(Py_buffer *view, bool ownview = true)
: buffer_info(view->buf, view->itemsize, view->format, view->ndim,
- {view->shape, view->shape + view->ndim}, {view->strides, view->strides + view->ndim}) {
+ {view->shape, view->shape + view->ndim}, {view->strides, view->strides + view->ndim}, view->readonly) {
this->view = view;
this->ownview = ownview;
}
@@ -70,6 +75,7 @@
strides = std::move(rhs.strides);
std::swap(view, rhs.view);
std::swap(ownview, rhs.ownview);
+ readonly = rhs.readonly;
return *this;
}
@@ -81,8 +87,8 @@
struct private_ctr_tag { };
buffer_info(private_ctr_tag, void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim,
- detail::any_container<ssize_t> &&shape_in, detail::any_container<ssize_t> &&strides_in)
- : buffer_info(ptr, itemsize, format, ndim, std::move(shape_in), std::move(strides_in)) { }
+ detail::any_container<ssize_t> &&shape_in, detail::any_container<ssize_t> &&strides_in, bool readonly)
+ : buffer_info(ptr, itemsize, format, ndim, std::move(shape_in), std::move(strides_in), readonly) { }
Py_buffer *view = nullptr;
bool ownview = false;
diff --git a/include/pybind11/detail/class.h b/include/pybind11/detail/class.h
index 230ae81..edfa7de 100644
--- a/include/pybind11/detail/class.h
+++ b/include/pybind11/detail/class.h
@@ -491,6 +491,13 @@
view->len = view->itemsize;
for (auto s : info->shape)
view->len *= s;
+ view->readonly = info->readonly;
+ if ((flags & PyBUF_WRITABLE) == PyBUF_WRITABLE && info->readonly) {
+ if (view)
+ view->obj = nullptr;
+ PyErr_SetString(PyExc_BufferError, "Writable buffer requested for readonly storage");
+ return -1;
+ }
if ((flags & PyBUF_FORMAT) == PyBUF_FORMAT)
view->format = const_cast<char *>(info->format.c_str());
if ((flags & PyBUF_STRIDES) == PyBUF_STRIDES) {
diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index 96eab96..4003d69 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -1345,7 +1345,7 @@
buf.strides = py_strides.data();
buf.shape = py_shape.data();
buf.suboffsets = nullptr;
- buf.readonly = false;
+ buf.readonly = info.readonly;
buf.internal = nullptr;
m_ptr = PyMemoryView_FromBuffer(&buf);
diff --git a/tests/constructor_stats.h b/tests/constructor_stats.h
index f026e70..431e5ac 100644
--- a/tests/constructor_stats.h
+++ b/tests/constructor_stats.h
@@ -180,7 +180,7 @@
}
}
}
- catch (const std::out_of_range &) {}
+ catch (const std::out_of_range&) {}
if (!t1) throw std::runtime_error("Unknown class passed to ConstructorStats::get()");
auto &cs1 = get(*t1);
// If we have both a t1 and t2 match, one is probably the trampoline class; return whichever
diff --git a/tests/test_buffers.cpp b/tests/test_buffers.cpp
index 433dfee..1bc67ff 100644
--- a/tests/test_buffers.cpp
+++ b/tests/test_buffers.cpp
@@ -166,4 +166,30 @@
.def_readwrite("value", (int32_t DerivedBuffer::*) &DerivedBuffer::value)
.def_buffer(&DerivedBuffer::get_buffer_info);
+ struct BufferReadOnly {
+ const uint8_t value = 0;
+ BufferReadOnly(uint8_t value): value(value) {}
+
+ py::buffer_info get_buffer_info() {
+ return py::buffer_info(&value, 1);
+ }
+ };
+ py::class_<BufferReadOnly>(m, "BufferReadOnly", py::buffer_protocol())
+ .def(py::init<uint8_t>())
+ .def_buffer(&BufferReadOnly::get_buffer_info);
+
+ struct BufferReadOnlySelect {
+ uint8_t value = 0;
+ bool readonly = false;
+
+ py::buffer_info get_buffer_info() {
+ return py::buffer_info(&value, 1, readonly);
+ }
+ };
+ py::class_<BufferReadOnlySelect>(m, "BufferReadOnlySelect", py::buffer_protocol())
+ .def(py::init<>())
+ .def_readwrite("value", &BufferReadOnlySelect::value)
+ .def_readwrite("readonly", &BufferReadOnlySelect::readonly)
+ .def_buffer(&BufferReadOnlySelect::get_buffer_info);
+
}
diff --git a/tests/test_buffers.py b/tests/test_buffers.py
index f006552..bf7aaed 100644
--- a/tests/test_buffers.py
+++ b/tests/test_buffers.py
@@ -1,8 +1,14 @@
+import io
import struct
+import sys
+
import pytest
+
from pybind11_tests import buffers as m
from pybind11_tests import ConstructorStats
+PY3 = sys.version_info[0] >= 3
+
pytestmark = pytest.requires_numpy
with pytest.suppress(ImportError):
@@ -85,3 +91,28 @@
buf.value = 0x12345678
value = struct.unpack('i', bytearray(buf))[0]
assert value == 0x12345678
+
+
+@pytest.unsupported_on_pypy
+def test_readonly_buffer():
+ buf = m.BufferReadOnly(0x64)
+ view = memoryview(buf)
+ assert view[0] == 0x64 if PY3 else b'd'
+ assert view.readonly
+
+
+@pytest.unsupported_on_pypy
+def test_selective_readonly_buffer():
+ buf = m.BufferReadOnlySelect()
+
+ memoryview(buf)[0] = 0x64 if PY3 else b'd'
+ assert buf.value == 0x64
+
+ io.BytesIO(b'A').readinto(buf)
+ assert buf.value == ord(b'A')
+
+ buf.readonly = True
+ with pytest.raises(TypeError):
+ memoryview(buf)[0] = 0 if PY3 else b'\0'
+ with pytest.raises(TypeError):
+ io.BytesIO(b'1').readinto(buf)