view mercurial/pythoncapi_compat.h @ 49275:c6a3243567b6

chg: replace mercurial.util.recvfds() by simpler pure Python implementation

On Python 3, we have socket.socket.recvmsg(). This makes it possible to receive
FDs in pure Python code. The new code behaves like the previous
implementations, except that it’s more strict about the format of the ancillary
data. This works because we know in which format the FDs are passed.

Because the code is (and always has been) specific to chg (payload is 1 byte,
number of passed FDs is limited) and we now have only one implementation and
the code is very short, I decided to stop exposing a function in
mercurial.util.

Note on terminology: The SCM_RIGHTS mechanism is used to share open file
descriptions to another process over a socket. The sending side passes an array
of file descriptors and the receiving side receives an array of file
descriptors. The file descriptors are different in general on both sides but
refer to the same open file descriptions. The two terms are often conflated,
even in the official documentation. That’s why I used “FD” above, which could
mean both “file descriptor” and “file description”.

// Header file providing new functions of the Python C API to old Python
// versions.
//
// File distributed under the MIT license.
//
// Homepage:
// https://github.com/pythoncapi/pythoncapi_compat
//
// Latest version:
// https://raw.githubusercontent.com/pythoncapi/pythoncapi_compat/master/pythoncapi_compat.h

#ifndef PYTHONCAPI_COMPAT
#define PYTHONCAPI_COMPAT

#ifdef __cplusplus
extern "C" {
#endif

#include <Python.h>
#include "frameobject.h"          // PyFrameObject, PyFrame_GetBack()


/* VC 2008 doesn't know about the inline keyword. */
#if defined(_MSC_VER) && _MSC_VER < 1900
#define inline __forceinline
#endif

// Cast argument to PyObject* type.
#ifndef _PyObject_CAST
#  define _PyObject_CAST(op) ((PyObject*)(op))
#endif


// bpo-42262 added Py_NewRef() to Python 3.10.0a3
#if PY_VERSION_HEX < 0x030a00A3 && !defined(Py_NewRef)
static inline PyObject* _Py_NewRef(PyObject *obj)
{
    Py_INCREF(obj);
    return obj;
}
#define Py_NewRef(obj) _Py_NewRef(_PyObject_CAST(obj))
#endif


// bpo-42262 added Py_XNewRef() to Python 3.10.0a3
#if PY_VERSION_HEX < 0x030a00A3 && !defined(Py_XNewRef)
static inline PyObject* _Py_XNewRef(PyObject *obj)
{
    Py_XINCREF(obj);
    return obj;
}
#define Py_XNewRef(obj) _Py_XNewRef(_PyObject_CAST(obj))
#endif


// bpo-39573 added Py_SET_REFCNT() to Python 3.9.0a4
#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_REFCNT)
static inline void _Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt)
{
    ob->ob_refcnt = refcnt;
}
#define Py_SET_REFCNT(ob, refcnt) _Py_SET_REFCNT((PyObject*)(ob), refcnt)
#endif


// bpo-39573 added Py_SET_TYPE() to Python 3.9.0a4
#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_TYPE)
static inline void
_Py_SET_TYPE(PyObject *ob, PyTypeObject *type)
{
    ob->ob_type = type;
}
#define Py_SET_TYPE(ob, type) _Py_SET_TYPE((PyObject*)(ob), type)
#endif


// bpo-39573 added Py_SET_SIZE() to Python 3.9.0a4
#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_SIZE)
static inline void
_Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
{
    ob->ob_size = size;
}
#define Py_SET_SIZE(ob, size) _Py_SET_SIZE((PyVarObject*)(ob), size)
#endif


// bpo-40421 added PyFrame_GetCode() to Python 3.9.0b1
#if PY_VERSION_HEX < 0x030900B1
static inline PyCodeObject*
PyFrame_GetCode(PyFrameObject *frame)
{
    PyCodeObject *code;
    assert(frame != NULL);
    code = frame->f_code;
    assert(code != NULL);
    Py_INCREF(code);
    return code;
}
#endif

static inline PyCodeObject*
_PyFrame_GetCodeBorrow(PyFrameObject *frame)
{
    PyCodeObject *code = PyFrame_GetCode(frame);
    Py_DECREF(code);
    return code;  // borrowed reference
}


// bpo-40421 added PyFrame_GetCode() to Python 3.9.0b1
#if PY_VERSION_HEX < 0x030900B1
static inline PyFrameObject*
PyFrame_GetBack(PyFrameObject *frame)
{
    PyFrameObject *back;
    assert(frame != NULL);
    back = frame->f_back;
    Py_XINCREF(back);
    return back;
}
#endif

static inline PyFrameObject*
_PyFrame_GetBackBorrow(PyFrameObject *frame)
{
    PyFrameObject *back = PyFrame_GetBack(frame);
    Py_XDECREF(back);
    return back;  // borrowed reference
}


// bpo-39947 added PyThreadState_GetInterpreter() to Python 3.9.0a5
#if PY_VERSION_HEX < 0x030900A5
static inline PyInterpreterState *
PyThreadState_GetInterpreter(PyThreadState *tstate)
{
    assert(tstate != NULL);
    return tstate->interp;
}
#endif


// bpo-40429 added PyThreadState_GetFrame() to Python 3.9.0b1
#if PY_VERSION_HEX < 0x030900B1
static inline PyFrameObject*
PyThreadState_GetFrame(PyThreadState *tstate)
{
    PyFrameObject *frame;
    assert(tstate != NULL);
    frame = tstate->frame;
    Py_XINCREF(frame);
    return frame;
}
#endif

static inline PyFrameObject*
_PyThreadState_GetFrameBorrow(PyThreadState *tstate)
{
    PyFrameObject *frame = PyThreadState_GetFrame(tstate);
    Py_XDECREF(frame);
    return frame;  // borrowed reference
}


// bpo-39947 added PyInterpreterState_Get() to Python 3.9.0a5
#if PY_VERSION_HEX < 0x030900A5
static inline PyInterpreterState *
PyInterpreterState_Get(void)
{
    PyThreadState *tstate;
    PyInterpreterState *interp;

    tstate = PyThreadState_GET();
    if (tstate == NULL) {
        Py_FatalError("GIL released (tstate is NULL)");
    }
    interp = tstate->interp;
    if (interp == NULL) {
        Py_FatalError("no current interpreter");
    }
    return interp;
}
#endif


// bpo-39947 added PyInterpreterState_Get() to Python 3.9.0a6
#if 0x030700A1 <= PY_VERSION_HEX && PY_VERSION_HEX < 0x030900A6
static inline uint64_t
PyThreadState_GetID(PyThreadState *tstate)
{
    assert(tstate != NULL);
    return tstate->id;
}
#endif


// bpo-37194 added PyObject_CallNoArgs() to Python 3.9.0a1
#if PY_VERSION_HEX < 0x030900A1
static inline PyObject*
PyObject_CallNoArgs(PyObject *func)
{
    return PyObject_CallFunctionObjArgs(func, NULL);
}
#endif


// bpo-39245 made PyObject_CallOneArg() public (previously called
// _PyObject_CallOneArg) in Python 3.9.0a4
#if PY_VERSION_HEX < 0x030900A4
static inline PyObject*
PyObject_CallOneArg(PyObject *func, PyObject *arg)
{
    return PyObject_CallFunctionObjArgs(func, arg, NULL);
}
#endif


// bpo-40024 added PyModule_AddType() to Python 3.9.0a5
#if PY_VERSION_HEX < 0x030900A5
static inline int
PyModule_AddType(PyObject *module, PyTypeObject *type)
{
    const char *name, *dot;

    if (PyType_Ready(type) < 0) {
        return -1;
    }

    // inline _PyType_Name()
    name = type->tp_name;
    assert(name != NULL);
    dot = strrchr(name, '.');
    if (dot != NULL) {
        name = dot + 1;
    }

    Py_INCREF(type);
    if (PyModule_AddObject(module, name, (PyObject *)type) < 0) {
        Py_DECREF(type);
        return -1;
    }

    return 0;
}
#endif


// bpo-40241 added PyObject_GC_IsTracked() to Python 3.9.0a6.
// bpo-4688 added _PyObject_GC_IS_TRACKED() to Python 2.7.0a2.
#if PY_VERSION_HEX < 0x030900A6
static inline int
PyObject_GC_IsTracked(PyObject* obj)
{
    return (PyObject_IS_GC(obj) && _PyObject_GC_IS_TRACKED(obj));
}
#endif

// bpo-40241 added PyObject_GC_IsFinalized() to Python 3.9.0a6.
// bpo-18112 added _PyGCHead_FINALIZED() to Python 3.4.0 final.
#if PY_VERSION_HEX < 0x030900A6 && PY_VERSION_HEX >= 0x030400F0
static inline int
PyObject_GC_IsFinalized(PyObject *obj)
{
    return (PyObject_IS_GC(obj) && _PyGCHead_FINALIZED((PyGC_Head *)(obj)-1));
}
#endif


// bpo-39573 added Py_IS_TYPE() to Python 3.9.0a4
#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_IS_TYPE)
static inline int
_Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {
    return ob->ob_type == type;
}
#define Py_IS_TYPE(ob, type) _Py_IS_TYPE((const PyObject*)(ob), type)
#endif


#ifdef __cplusplus
}
#endif
#endif  // PYTHONCAPI_COMPAT