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1 /*
2     pybind11/detail/internals.h: Internal data structure and related functions
3 
4     Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
5 
6     All rights reserved. Use of this source code is governed by a
7     BSD-style license that can be found in the LICENSE file.
8 */
9 
10 #pragma once
11 
12 #include "../pytypes.h"
13 
14 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
15 PYBIND11_NAMESPACE_BEGIN(detail)
16 // Forward declarations
17 inline PyTypeObject *make_static_property_type();
18 inline PyTypeObject *make_default_metaclass();
19 inline PyObject *make_object_base_type(PyTypeObject *metaclass);
20 
21 // The old Python Thread Local Storage (TLS) API is deprecated in Python 3.7 in favor of the new
22 // Thread Specific Storage (TSS) API.
23 #if PY_VERSION_HEX >= 0x03070000
24 #    define PYBIND11_TLS_KEY_INIT(var) Py_tss_t *var = nullptr
25 #    define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get((key))
26 #    define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set((key), (value))
27 #    define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set((key), nullptr)
28 #    define PYBIND11_TLS_FREE(key) PyThread_tss_free(key)
29 #else
30     // Usually an int but a long on Cygwin64 with Python 3.x
31 #    define PYBIND11_TLS_KEY_INIT(var) decltype(PyThread_create_key()) var = 0
32 #    define PYBIND11_TLS_GET_VALUE(key) PyThread_get_key_value((key))
33 #    if PY_MAJOR_VERSION < 3
34 #        define PYBIND11_TLS_DELETE_VALUE(key)                               \
35              PyThread_delete_key_value(key)
36 #        define PYBIND11_TLS_REPLACE_VALUE(key, value)                       \
37              do {                                                            \
38                  PyThread_delete_key_value((key));                           \
39                  PyThread_set_key_value((key), (value));                     \
40              } while (false)
41 #    else
42 #        define PYBIND11_TLS_DELETE_VALUE(key)                               \
43              PyThread_set_key_value((key), nullptr)
44 #        define PYBIND11_TLS_REPLACE_VALUE(key, value)                       \
45              PyThread_set_key_value((key), (value))
46 #    endif
47 #    define PYBIND11_TLS_FREE(key) (void)key
48 #endif
49 
50 // Python loads modules by default with dlopen with the RTLD_LOCAL flag; under libc++ and possibly
51 // other STLs, this means `typeid(A)` from one module won't equal `typeid(A)` from another module
52 // even when `A` is the same, non-hidden-visibility type (e.g. from a common include).  Under
53 // libstdc++, this doesn't happen: equality and the type_index hash are based on the type name,
54 // which works.  If not under a known-good stl, provide our own name-based hash and equality
55 // functions that use the type name.
56 #if defined(__GLIBCXX__)
same_type(const std::type_info & lhs,const std::type_info & rhs)57 inline bool same_type(const std::type_info &lhs, const std::type_info &rhs) { return lhs == rhs; }
58 using type_hash = std::hash<std::type_index>;
59 using type_equal_to = std::equal_to<std::type_index>;
60 #else
same_type(const std::type_info & lhs,const std::type_info & rhs)61 inline bool same_type(const std::type_info &lhs, const std::type_info &rhs) {
62     return lhs.name() == rhs.name() || std::strcmp(lhs.name(), rhs.name()) == 0;
63 }
64 
65 struct type_hash {
operatortype_hash66     size_t operator()(const std::type_index &t) const {
67         size_t hash = 5381;
68         const char *ptr = t.name();
69         while (auto c = static_cast<unsigned char>(*ptr++))
70             hash = (hash * 33) ^ c;
71         return hash;
72     }
73 };
74 
75 struct type_equal_to {
operatortype_equal_to76     bool operator()(const std::type_index &lhs, const std::type_index &rhs) const {
77         return lhs.name() == rhs.name() || std::strcmp(lhs.name(), rhs.name()) == 0;
78     }
79 };
80 #endif
81 
82 template <typename value_type>
83 using type_map = std::unordered_map<std::type_index, value_type, type_hash, type_equal_to>;
84 
85 struct override_hash {
operatoroverride_hash86     inline size_t operator()(const std::pair<const PyObject *, const char *>& v) const {
87         size_t value = std::hash<const void *>()(v.first);
88         value ^= std::hash<const void *>()(v.second) + 0x9e3779b9 + (value<<6) + (value>>2);
89         return value;
90     }
91 };
92 
93 /// Internal data structure used to track registered instances and types.
94 /// Whenever binary incompatible changes are made to this structure,
95 /// `PYBIND11_INTERNALS_VERSION` must be incremented.
96 struct internals {
97     type_map<type_info *> registered_types_cpp; // std::type_index -> pybind11's type information
98     std::unordered_map<PyTypeObject *, std::vector<type_info *>> registered_types_py; // PyTypeObject* -> base type_info(s)
99     std::unordered_multimap<const void *, instance*> registered_instances; // void * -> instance*
100     std::unordered_set<std::pair<const PyObject *, const char *>, override_hash> inactive_override_cache;
101     type_map<std::vector<bool (*)(PyObject *, void *&)>> direct_conversions;
102     std::unordered_map<const PyObject *, std::vector<PyObject *>> patients;
103     std::forward_list<void (*) (std::exception_ptr)> registered_exception_translators;
104     std::unordered_map<std::string, void *> shared_data; // Custom data to be shared across extensions
105     std::vector<PyObject *> loader_patient_stack; // Used by `loader_life_support`
106     std::forward_list<std::string> static_strings; // Stores the std::strings backing detail::c_str()
107     PyTypeObject *static_property_type;
108     PyTypeObject *default_metaclass;
109     PyObject *instance_base;
110 #if defined(WITH_THREAD)
111     PYBIND11_TLS_KEY_INIT(tstate);
112     PyInterpreterState *istate = nullptr;
~internalsinternals113     ~internals() {
114         // This destructor is called *after* Py_Finalize() in finalize_interpreter().
115         // That *SHOULD BE* fine. The following details what happens when PyThread_tss_free is called.
116         // PYBIND11_TLS_FREE is PyThread_tss_free on python 3.7+. On older python, it does nothing.
117         // PyThread_tss_free calls PyThread_tss_delete and PyMem_RawFree.
118         // PyThread_tss_delete just calls TlsFree (on Windows) or pthread_key_delete (on *NIX). Neither
119         // of those have anything to do with CPython internals.
120         // PyMem_RawFree *requires* that the `tstate` be allocated with the CPython allocator.
121         PYBIND11_TLS_FREE(tstate);
122     }
123 #endif
124 };
125 
126 /// Additional type information which does not fit into the PyTypeObject.
127 /// Changes to this struct also require bumping `PYBIND11_INTERNALS_VERSION`.
128 struct type_info {
129     PyTypeObject *type;
130     const std::type_info *cpptype;
131     size_t type_size, type_align, holder_size_in_ptrs;
132     void *(*operator_new)(size_t);
133     void (*init_instance)(instance *, const void *);
134     void (*dealloc)(value_and_holder &v_h);
135     std::vector<PyObject *(*)(PyObject *, PyTypeObject *)> implicit_conversions;
136     std::vector<std::pair<const std::type_info *, void *(*)(void *)>> implicit_casts;
137     std::vector<bool (*)(PyObject *, void *&)> *direct_conversions;
138     buffer_info *(*get_buffer)(PyObject *, void *) = nullptr;
139     void *get_buffer_data = nullptr;
140     void *(*module_local_load)(PyObject *, const type_info *) = nullptr;
141     /* A simple type never occurs as a (direct or indirect) parent
142      * of a class that makes use of multiple inheritance */
143     bool simple_type : 1;
144     /* True if there is no multiple inheritance in this type's inheritance tree */
145     bool simple_ancestors : 1;
146     /* for base vs derived holder_type checks */
147     bool default_holder : 1;
148     /* true if this is a type registered with py::module_local */
149     bool module_local : 1;
150 };
151 
152 /// Tracks the `internals` and `type_info` ABI version independent of the main library version
153 #define PYBIND11_INTERNALS_VERSION 4
154 
155 /// On MSVC, debug and release builds are not ABI-compatible!
156 #if defined(_MSC_VER) && defined(_DEBUG)
157 #  define PYBIND11_BUILD_TYPE "_debug"
158 #else
159 #  define PYBIND11_BUILD_TYPE ""
160 #endif
161 
162 /// Let's assume that different compilers are ABI-incompatible.
163 /// A user can manually set this string if they know their
164 /// compiler is compatible.
165 #ifndef PYBIND11_COMPILER_TYPE
166 #  if defined(_MSC_VER)
167 #    define PYBIND11_COMPILER_TYPE "_msvc"
168 #  elif defined(__INTEL_COMPILER)
169 #    define PYBIND11_COMPILER_TYPE "_icc"
170 #  elif defined(__clang__)
171 #    define PYBIND11_COMPILER_TYPE "_clang"
172 #  elif defined(__PGI)
173 #    define PYBIND11_COMPILER_TYPE "_pgi"
174 #  elif defined(__MINGW32__)
175 #    define PYBIND11_COMPILER_TYPE "_mingw"
176 #  elif defined(__CYGWIN__)
177 #    define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
178 #  elif defined(__GNUC__)
179 #    define PYBIND11_COMPILER_TYPE "_gcc"
180 #  else
181 #    define PYBIND11_COMPILER_TYPE "_unknown"
182 #  endif
183 #endif
184 
185 /// Also standard libs
186 #ifndef PYBIND11_STDLIB
187 #  if defined(_LIBCPP_VERSION)
188 #    define PYBIND11_STDLIB "_libcpp"
189 #  elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
190 #    define PYBIND11_STDLIB "_libstdcpp"
191 #  else
192 #    define PYBIND11_STDLIB ""
193 #  endif
194 #endif
195 
196 /// On Linux/OSX, changes in __GXX_ABI_VERSION__ indicate ABI incompatibility.
197 #ifndef PYBIND11_BUILD_ABI
198 #  if defined(__GXX_ABI_VERSION)
199 #    define PYBIND11_BUILD_ABI "_cxxabi" PYBIND11_TOSTRING(__GXX_ABI_VERSION)
200 #  else
201 #    define PYBIND11_BUILD_ABI ""
202 #  endif
203 #endif
204 
205 #ifndef PYBIND11_INTERNALS_KIND
206 #  if defined(WITH_THREAD)
207 #    define PYBIND11_INTERNALS_KIND ""
208 #  else
209 #    define PYBIND11_INTERNALS_KIND "_without_thread"
210 #  endif
211 #endif
212 
213 #define PYBIND11_INTERNALS_ID "__pybind11_internals_v" \
214     PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION) PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
215 
216 #define PYBIND11_MODULE_LOCAL_ID "__pybind11_module_local_v" \
217     PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION) PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
218 
219 /// Each module locally stores a pointer to the `internals` data. The data
220 /// itself is shared among modules with the same `PYBIND11_INTERNALS_ID`.
get_internals_pp()221 inline internals **&get_internals_pp() {
222     static internals **internals_pp = nullptr;
223     return internals_pp;
224 }
225 
translate_exception(std::exception_ptr p)226 inline void translate_exception(std::exception_ptr p) {
227     try {
228         if (p) std::rethrow_exception(p);
229     } catch (error_already_set &e)           { e.restore();                                    return;
230     } catch (const builtin_exception &e)     { e.set_error();                                  return;
231     } catch (const std::bad_alloc &e)        { PyErr_SetString(PyExc_MemoryError,   e.what()); return;
232     } catch (const std::domain_error &e)     { PyErr_SetString(PyExc_ValueError,    e.what()); return;
233     } catch (const std::invalid_argument &e) { PyErr_SetString(PyExc_ValueError,    e.what()); return;
234     } catch (const std::length_error &e)     { PyErr_SetString(PyExc_ValueError,    e.what()); return;
235     } catch (const std::out_of_range &e)     { PyErr_SetString(PyExc_IndexError,    e.what()); return;
236     } catch (const std::range_error &e)      { PyErr_SetString(PyExc_ValueError,    e.what()); return;
237     } catch (const std::overflow_error &e)   { PyErr_SetString(PyExc_OverflowError, e.what()); return;
238     } catch (const std::exception &e)        { PyErr_SetString(PyExc_RuntimeError,  e.what()); return;
239     } catch (...) {
240         PyErr_SetString(PyExc_RuntimeError, "Caught an unknown exception!");
241         return;
242     }
243 }
244 
245 #if !defined(__GLIBCXX__)
translate_local_exception(std::exception_ptr p)246 inline void translate_local_exception(std::exception_ptr p) {
247     try {
248         if (p) std::rethrow_exception(p);
249     } catch (error_already_set &e)       { e.restore();   return;
250     } catch (const builtin_exception &e) { e.set_error(); return;
251     }
252 }
253 #endif
254 
255 /// Return a reference to the current `internals` data
get_internals()256 PYBIND11_NOINLINE inline internals &get_internals() {
257     auto **&internals_pp = get_internals_pp();
258     if (internals_pp && *internals_pp)
259         return **internals_pp;
260 
261     // Ensure that the GIL is held since we will need to make Python calls.
262     // Cannot use py::gil_scoped_acquire here since that constructor calls get_internals.
263     struct gil_scoped_acquire_local {
264         gil_scoped_acquire_local() : state (PyGILState_Ensure()) {}
265         ~gil_scoped_acquire_local() { PyGILState_Release(state); }
266         const PyGILState_STATE state;
267     } gil;
268 
269     PYBIND11_STR_TYPE id(PYBIND11_INTERNALS_ID);
270     auto builtins = handle(PyEval_GetBuiltins());
271     if (builtins.contains(id) && isinstance<capsule>(builtins[id])) {
272         internals_pp = static_cast<internals **>(capsule(builtins[id]));
273 
274         // We loaded builtins through python's builtins, which means that our `error_already_set`
275         // and `builtin_exception` may be different local classes than the ones set up in the
276         // initial exception translator, below, so add another for our local exception classes.
277         //
278         // libstdc++ doesn't require this (types there are identified only by name)
279 #if !defined(__GLIBCXX__)
280         (*internals_pp)->registered_exception_translators.push_front(&translate_local_exception);
281 #endif
282     } else {
283         if (!internals_pp) internals_pp = new internals*();
284         auto *&internals_ptr = *internals_pp;
285         internals_ptr = new internals();
286 #if defined(WITH_THREAD)
287 
288         #if PY_VERSION_HEX < 0x03090000
289                 PyEval_InitThreads();
290         #endif
291         PyThreadState *tstate = PyThreadState_Get();
292         #if PY_VERSION_HEX >= 0x03070000
293             internals_ptr->tstate = PyThread_tss_alloc();
294             if (!internals_ptr->tstate || PyThread_tss_create(internals_ptr->tstate))
295                 pybind11_fail("get_internals: could not successfully initialize the TSS key!");
296             PyThread_tss_set(internals_ptr->tstate, tstate);
297         #else
298             internals_ptr->tstate = PyThread_create_key();
299             if (internals_ptr->tstate == -1)
300                 pybind11_fail("get_internals: could not successfully initialize the TLS key!");
301             PyThread_set_key_value(internals_ptr->tstate, tstate);
302         #endif
303         internals_ptr->istate = tstate->interp;
304 #endif
305         builtins[id] = capsule(internals_pp);
306         internals_ptr->registered_exception_translators.push_front(&translate_exception);
307         internals_ptr->static_property_type = make_static_property_type();
308         internals_ptr->default_metaclass = make_default_metaclass();
309         internals_ptr->instance_base = make_object_base_type(internals_ptr->default_metaclass);
310     }
311     return **internals_pp;
312 }
313 
314 /// Works like `internals.registered_types_cpp`, but for module-local registered types:
registered_local_types_cpp()315 inline type_map<type_info *> &registered_local_types_cpp() {
316     static type_map<type_info *> locals{};
317     return locals;
318 }
319 
320 /// Constructs a std::string with the given arguments, stores it in `internals`, and returns its
321 /// `c_str()`.  Such strings objects have a long storage duration -- the internal strings are only
322 /// cleared when the program exits or after interpreter shutdown (when embedding), and so are
323 /// suitable for c-style strings needed by Python internals (such as PyTypeObject's tp_name).
324 template <typename... Args>
c_str(Args &&...args)325 const char *c_str(Args &&...args) {
326     auto &strings = get_internals().static_strings;
327     strings.emplace_front(std::forward<Args>(args)...);
328     return strings.front().c_str();
329 }
330 
PYBIND11_NAMESPACE_END(detail)331 PYBIND11_NAMESPACE_END(detail)
332 
333 /// Returns a named pointer that is shared among all extension modules (using the same
334 /// pybind11 version) running in the current interpreter. Names starting with underscores
335 /// are reserved for internal usage. Returns `nullptr` if no matching entry was found.
336 inline PYBIND11_NOINLINE void *get_shared_data(const std::string &name) {
337     auto &internals = detail::get_internals();
338     auto it = internals.shared_data.find(name);
339     return it != internals.shared_data.end() ? it->second : nullptr;
340 }
341 
342 /// Set the shared data that can be later recovered by `get_shared_data()`.
set_shared_data(const std::string & name,void * data)343 inline PYBIND11_NOINLINE void *set_shared_data(const std::string &name, void *data) {
344     detail::get_internals().shared_data[name] = data;
345     return data;
346 }
347 
348 /// Returns a typed reference to a shared data entry (by using `get_shared_data()`) if
349 /// such entry exists. Otherwise, a new object of default-constructible type `T` is
350 /// added to the shared data under the given name and a reference to it is returned.
351 template<typename T>
get_or_create_shared_data(const std::string & name)352 T &get_or_create_shared_data(const std::string &name) {
353     auto &internals = detail::get_internals();
354     auto it = internals.shared_data.find(name);
355     T *ptr = (T *) (it != internals.shared_data.end() ? it->second : nullptr);
356     if (!ptr) {
357         ptr = new T();
358         internals.shared_data[name] = ptr;
359     }
360     return *ptr;
361 }
362 
363 PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
364