diff --git a/BUILD b/BUILD index 25bd717f4e..c4b517cfa7 100644 --- a/BUILD +++ b/BUILD @@ -671,6 +671,7 @@ cc_binary( linkstatic = 1, deps = [ ":protobuf", + ":proto_api", ] + select({ "//conditions:default": [], ":use_fast_cpp_protos": ["//external:python_headers"], @@ -813,6 +814,15 @@ internal_protobuf_py_tests( deps = [":python_tests"], ) +cc_library( + name = "proto_api", + hdrs = ["python/google/protobuf/proto_api.h"], + deps = [ + ":protobuf_python", + "//external:python_headers", + ], +) + proto_lang_toolchain( name = "cc_toolchain", command_line = "--cpp_out=$(OUT)", diff --git a/Makefile.am b/Makefile.am index 8334db6095..ac87e8a396 100644 --- a/Makefile.am +++ b/Makefile.am @@ -804,6 +804,7 @@ python_EXTRA_DIST= \ python/google/protobuf/message.py \ python/google/protobuf/message_factory.py \ python/google/protobuf/python_protobuf.h \ + python/google/protobuf/proto_api.h \ python/google/protobuf/proto_builder.py \ python/google/protobuf/pyext/README \ python/google/protobuf/pyext/__init__.py \ diff --git a/python/google/protobuf/proto_api.h b/python/google/protobuf/proto_api.h new file mode 100644 index 0000000000..64d8dda983 --- /dev/null +++ b/python/google/protobuf/proto_api.h @@ -0,0 +1,92 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// This file can be included by other C++ libraries, typically extension modules +// which want to interact with the Python Messages coming from the "cpp" +// implementation of protocol buffers. +// +// Usage: +// Declare a (probably static) variable to hold the API: +// const PyProto_API* py_proto_api; +// In some initialization function, write: +// py_proto_api = static_cast(PyCapsule_Import( +// PyProtoAPICapsuleName(), 0)); +// if (!py_proto_api) { ...handle ImportError... } +// Then use the methods of the returned class: +// py_proto_api->GetMessagePointer(...); + +#ifndef PYTHON_GOOGLE_PROTOBUF_PROTO_API_H__ +#define PYTHON_GOOGLE_PROTOBUF_PROTO_API_H__ + +#include + +namespace google { +namespace protobuf { + +class Message; + +namespace python { + +// Note on the implementation: +// This API is designed after +// https://docs.python.org/3/extending/extending.html#providing-a-c-api-for-an-extension-module +// The class below contains no mutable state, and all methods are "const"; +// we use a C++ class instead of a C struct with functions pointers just because +// the code looks more readable. +struct PyProto_API { + // The API object is created at initialization time and never freed. + // This destructor is never called. + virtual ~PyProto_API() {} + + // Operations on Messages. + + // If the passed object is a Python Message, returns its internal pointer. + // Otherwise, returns NULL with an exception set. + virtual const Message* GetMessagePointer(PyObject* msg) const = 0; + + // If the passed object is a Python Message, returns a mutable pointer. + // Otherwise, returns NULL with an exception set. + // This function will succeed only if there are no other Python objects + // pointing to the message, like submessages or repeated containers. + // With the current implementation, only empty messages are in this case. + virtual Message* GetMutableMessagePointer(PyObject* msg) const = 0; +}; + +inline const char* PyProtoAPICapsuleName() { + static const char kCapsuleName[] = + "protobuf.python.google.protobuf.cpp._message.proto_API"; + return kCapsuleName; +} + +} // namespace python +} // namespace protobuf +} // namespace google + +#endif // PYTHON_GOOGLE_PROTOBUF_PROTO_API_H__ diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc index 5893533adf..53736b9c9f 100644 --- a/python/google/protobuf/pyext/message.cc +++ b/python/google/protobuf/pyext/message.cc @@ -2866,17 +2866,38 @@ const Message* (*GetCProtoInsidePyProtoPtr)(PyObject* msg); Message* (*MutableCProtoInsidePyProtoPtr)(PyObject* msg); static const Message* GetCProtoInsidePyProtoImpl(PyObject* msg) { + const Message* message = PyMessage_GetMessagePointer(msg); + if (message == NULL) { + PyErr_Clear(); + return NULL; + } + return message; +} + +static Message* MutableCProtoInsidePyProtoImpl(PyObject* msg) { + Message* message = PyMessage_GetMutableMessagePointer(msg); + if (message == NULL) { + PyErr_Clear(); + return NULL; + } + return message; +} + +const Message* PyMessage_GetMessagePointer(PyObject* msg) { if (!PyObject_TypeCheck(msg, &CMessage_Type)) { + PyErr_SetString(PyExc_TypeError, "Not a Message instance"); return NULL; } CMessage* cmsg = reinterpret_cast(msg); return cmsg->message; } -static Message* MutableCProtoInsidePyProtoImpl(PyObject* msg) { +Message* PyMessage_GetMutableMessagePointer(PyObject* msg) { if (!PyObject_TypeCheck(msg, &CMessage_Type)) { + PyErr_SetString(PyExc_TypeError, "Not a Message instance"); return NULL; } + CMessage* cmsg = reinterpret_cast(msg); if ((cmsg->composite_fields && PyDict_Size(cmsg->composite_fields) != 0) || (cmsg->extensions != NULL && @@ -2885,6 +2906,9 @@ static Message* MutableCProtoInsidePyProtoImpl(PyObject* msg) { // the underlying C++ message back to the CMessage (e.g. removed repeated // composite containers). We only allow direct mutation of the underlying // C++ message if there is no child data in the CMessage. + PyErr_SetString(PyExc_ValueError, + "Cannot reliably get a mutable pointer " + "to a message with extra references"); return NULL; } cmessage::AssureWritable(cmsg); diff --git a/python/google/protobuf/pyext/message.h b/python/google/protobuf/pyext/message.h index 72bcfa83d9..d754e62adc 100644 --- a/python/google/protobuf/pyext/message.h +++ b/python/google/protobuf/pyext/message.h @@ -341,6 +341,9 @@ bool CheckFieldBelongsToMessage(const FieldDescriptor* field_descriptor, extern PyObject* PickleError_class; +const Message* PyMessage_GetMessagePointer(PyObject* msg); +Message* PyMessage_GetMutableMessagePointer(PyObject* msg); + bool InitProto2MessageModule(PyObject *m); #if LANG_CXX11 diff --git a/python/google/protobuf/pyext/message_module.cc b/python/google/protobuf/pyext/message_module.cc index 7c4df47f45..f5c8f2956e 100644 --- a/python/google/protobuf/pyext/message_module.cc +++ b/python/google/protobuf/pyext/message_module.cc @@ -31,9 +31,26 @@ #include #include +#include #include +namespace { + +// C++ API. Clients get at this via proto_api.h +struct ApiImplementation : google::protobuf::python::PyProto_API { + const google::protobuf::Message* + GetMessagePointer(PyObject* msg) const override { + return google::protobuf::python::PyMessage_GetMessagePointer(msg); + } + google::protobuf::Message* + GetMutableMessagePointer(PyObject* msg) const override { + return google::protobuf::python::PyMessage_GetMutableMessagePointer(msg); + } +}; + +} // namespace + static PyObject* GetPythonProto3PreserveUnknownsDefault( PyObject* /*m*/, PyObject* /*args*/) { if (google::protobuf::internal::GetProto3PreserveUnknownsDefault()) {