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pybind11_abseil
Commit 6776a520 by Ralf W. Grosse-Kunstleve Committed by Copybara-Service
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Add doc-comment for `RawPtrFromCapsule()` and factor out `VoidPtrFromCapsule()`. 

PiperOrigin-RevId: 487943835
parent 9f13dde9
Showing with 137 additions and 88 deletions
pybind11_abseil/BUILD
......@@ -77,6 +77,7 @@ cc_library(
cc_library(
name = "raw_ptr_from_capsule",
srcs = ["raw_ptr_from_capsule.cc"],
hdrs = ["raw_ptr_from_capsule.h"],
visibility = ["//visibility:private"],
deps = [
......
pybind11_abseil/raw_ptr_from_capsule.cc 0 → 100644
#include "pybind11_abseil/raw_ptr_from_capsule.h"
#include <Python.h>
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/str_cat.h"
namespace pybind11_abseil {
namespace raw_ptr_from_capsule {
namespace {
// Copied from pybind11/pytypes.h, to decouple from exception handling
// requirement.
// Equivalent to obj.__class__.__name__ (or obj.__name__ if obj is a class).
const char* obj_class_name(PyObject* obj) {
if (Py_TYPE(obj) == &PyType_Type) {
return reinterpret_cast<PyTypeObject*>(obj)->tp_name;
}
return Py_TYPE(obj)->tp_name;
}
std::string quoted_name_or_null_indicator(
const char* name, const char* quote = "\"",
const char* null_indicator = "NULL") {
return (name == nullptr ? null_indicator : absl::StrCat(quote, name, quote));
}
} // namespace
absl::StatusOr<void*> VoidPtrFromCapsule(PyObject* py_obj, const char* name,
const char* as_capsule_method_name) {
// Note: https://docs.python.org/3/c-api/capsule.html:
// The pointer argument may not be NULL.
if (PyCapsule_CheckExact(py_obj)) {
void* void_ptr = PyCapsule_GetPointer(py_obj, name);
if (PyErr_Occurred()) {
PyErr_Clear();
return absl::InvalidArgumentError(absl::StrCat(
"obj is a capsule with name ",
quoted_name_or_null_indicator(PyCapsule_GetName(py_obj)), " but ",
quoted_name_or_null_indicator(name), " is expected."));
}
return void_ptr;
}
if (as_capsule_method_name == nullptr) {
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), " object is not a capsule."));
}
PyObject* from_method =
PyObject_CallMethod(py_obj, as_capsule_method_name, nullptr);
if (from_method == nullptr) {
PyObject *ptype = nullptr, *pvalue = nullptr, *ptraceback = nullptr;
PyErr_Fetch(&ptype, &pvalue, &ptraceback);
PyErr_NormalizeException(&ptype, &pvalue, &ptraceback);
PyObject* err_msg_str = PyObject_Str(pvalue);
std::string err_msg;
if (err_msg_str == nullptr) {
PyErr_Clear();
err_msg = "<message unavailable>";
} else {
PyObject* err_msg_bytes =
PyUnicode_AsEncodedString(err_msg_str, "UTF-8", "replace");
Py_DECREF(err_msg_str);
if (err_msg_bytes == nullptr) {
PyErr_Clear();
err_msg = "<message unavailable>";
} else {
const char* err_msg_char_ptr = PyBytes_AsString(err_msg_bytes);
if (err_msg_char_ptr == nullptr) {
PyErr_Clear();
err_msg = "<message unavailable>";
} else {
err_msg = err_msg_char_ptr;
}
Py_DECREF(err_msg_bytes);
}
}
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), ".", as_capsule_method_name,
"() call failed: ", obj_class_name(ptype), ": ", err_msg));
}
if (!PyCapsule_CheckExact(from_method)) {
std::string returned_obj_type = obj_class_name(from_method);
Py_DECREF(from_method);
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), ".", as_capsule_method_name,
"() returned an object (", returned_obj_type,
") that is not a capsule."));
}
void* void_ptr = PyCapsule_GetPointer(from_method, name);
if (!PyErr_Occurred()) {
Py_DECREF(from_method);
return void_ptr;
}
PyErr_Clear();
std::string capsule_name =
quoted_name_or_null_indicator(PyCapsule_GetName(from_method));
Py_DECREF(from_method);
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), ".", as_capsule_method_name,
"() returned a capsule with name ", capsule_name, " but ",
quoted_name_or_null_indicator(name), " is expected."));
}
} // namespace raw_ptr_from_capsule
} // namespace pybind11_abseil
pybind11_abseil/raw_ptr_from_capsule.h
......@@ -4,103 +4,43 @@
// Must be first include (https://docs.python.org/3/c-api/intro.html).
#include <Python.h>
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/str_cat.h"
namespace pybind11_abseil {
namespace raw_ptr_from_capsule {
// Copied from pybind11/pytypes.h, to decouple from exception handling
// requirement.
// Equivalent to obj.__class__.__name__ (or obj.__name__ if obj is a class).
inline const char* obj_class_name(PyObject* obj) {
if (Py_TYPE(obj) == &PyType_Type) {
return reinterpret_cast<PyTypeObject*>(obj)->tp_name;
}
return Py_TYPE(obj)->tp_name;
}
inline std::string quoted_name_or_null_indicator(
const char* name, const char* quote = "\"",
const char* null_indicator = "NULL") {
return (name == nullptr ? null_indicator : absl::StrCat(quote, name, quote));
}
// Prefer RawPtrFromCapsule<T>(), to minimize the use of static_casts, and
// to keep them as close as possible to the context establishing type safety
// (via the capsule name).
absl::StatusOr<void*> VoidPtrFromCapsule(PyObject* py_obj, const char* name,
const char* as_capsule_method_name);
// Extract a raw pointer from a PyCapsule or return absl::InvalidArgumentError,
// with a detailed message.
// CAUTION: The returned raw pointer does (of course) not manage the lifetime
// of the pointee! It is best to use the raw pointer only for the
// duration of a function call, similar to e.g. std::string::c_str(),
// but not to store it in any way (e.g. as a data member of a
// long-lived object).
// If py_obj is a capsule, the capsule name is inspected. If it matches the
// name argument, the raw pointer is returned. Otherwise
// absl::InvalidArgumentError is returned. - Note that name can be nullptr,
// and can match a nullptr capsule name.
// If py_obj is not a capsule, and as_capsule_method_name is given (i.e. it is
// not nullptr), the py_obj method with that name will be called without
// arguments, with the expectation to receive a capsule object in return, from
// which the raw pointer is then extracted exactly as described above.
// A specific error message is generated for every possible error condition
// (most of the code in this function is for error handling).
template <typename T>
absl::StatusOr<T*> RawPtrFromCapsule(PyObject* py_obj, const char* name,
const char* as_capsule_method_name) {
// Note: https://docs.python.org/3/c-api/capsule.html:
// The pointer argument may not be NULL.
if (PyCapsule_CheckExact(py_obj)) {
void* void_ptr = PyCapsule_GetPointer(py_obj, name);
if (PyErr_Occurred()) {
PyErr_Clear();
return absl::InvalidArgumentError(absl::StrCat(
"obj is a capsule with name ",
quoted_name_or_null_indicator(PyCapsule_GetName(py_obj)), " but ",
quoted_name_or_null_indicator(name), " is expected."));
}
return static_cast<T*>(void_ptr);
}
if (as_capsule_method_name == nullptr) {
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), " object is not a capsule."));
}
PyObject* from_method =
PyObject_CallMethod(py_obj, as_capsule_method_name, nullptr);
if (from_method == nullptr) {
PyObject *ptype = nullptr, *pvalue = nullptr, *ptraceback = nullptr;
PyErr_Fetch(&ptype, &pvalue, &ptraceback);
PyErr_NormalizeException(&ptype, &pvalue, &ptraceback);
PyObject* err_msg_str = PyObject_Str(pvalue);
std::string err_msg;
if (err_msg_str == nullptr) {
PyErr_Clear();
err_msg = "<message unavailable>";
} else {
PyObject* err_msg_bytes =
PyUnicode_AsEncodedString(err_msg_str, "UTF-8", "replace");
Py_DECREF(err_msg_str);
if (err_msg_bytes == nullptr) {
PyErr_Clear();
err_msg = "<message unavailable>";
} else {
const char* err_msg_char_ptr = PyBytes_AsString(err_msg_bytes);
if (err_msg_char_ptr == nullptr) {
PyErr_Clear();
err_msg = "<message unavailable>";
} else {
err_msg = err_msg_char_ptr;
}
Py_DECREF(err_msg_bytes);
}
}
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), ".", as_capsule_method_name,
"() call failed: ", obj_class_name(ptype), ": ", err_msg));
}
if (!PyCapsule_CheckExact(from_method)) {
std::string returned_obj_type = obj_class_name(from_method);
Py_DECREF(from_method);
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), ".", as_capsule_method_name,
"() returned an object (", returned_obj_type,
") that is not a capsule."));
}
void* void_ptr = PyCapsule_GetPointer(from_method, name);
if (!PyErr_Occurred()) {
Py_DECREF(from_method);
return static_cast<T*>(void_ptr);
absl::StatusOr<void*> statusor_void_ptr =
VoidPtrFromCapsule(py_obj, name, as_capsule_method_name);
if (!statusor_void_ptr.ok()) {
return statusor_void_ptr.status();
}
PyErr_Clear();
std::string capsule_name =
quoted_name_or_null_indicator(PyCapsule_GetName(from_method));
Py_DECREF(from_method);
return absl::InvalidArgumentError(
absl::StrCat(obj_class_name(py_obj), ".", as_capsule_method_name,
"() returned a capsule with name ", capsule_name, " but ",
quoted_name_or_null_indicator(name), " is expected."));
return static_cast<T*>(statusor_void_ptr.value());
}
} // namespace raw_ptr_from_capsule
......
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