gh-111140: Adds PyLong_AsNativeBytes and PyLong_FromNative[Unsigned]Bytes functions (GH-114886)

Include/cpython/longobject.h

@@ -4,6 +4,40 @@
 
 PyAPI_FUNC(PyObject*) PyLong_FromUnicodeObject(PyObject *u, int base);
 
+/* PyLong_AsNativeBytes: Copy the integer value to a native variable.
+   buffer points to the first byte of the variable.
+   n_bytes is the number of bytes available in the buffer. Pass 0 to request
+   the required size for the value.
+   endianness is -1 for native endian, 0 for big endian or 1 for little.
+   Big endian mode will write the most significant byte into the address
+   directly referenced by buffer; little endian will write the least significant
+   byte into that address.
+
+   If an exception is raised, returns a negative value.
+   Otherwise, returns the number of bytes that are required to store the value.
+   To check that the full value is represented, ensure that the return value is
+   equal or less than n_bytes.
+   All n_bytes are guaranteed to be written (unless an exception occurs), and
+   so ignoring a positive return value is the equivalent of a downcast in C.
+   In cases where the full value could not be represented, the returned value
+   may be larger than necessary - this function is not an accurate way to
+   calculate the bit length of an integer object.
+   */
+PyAPI_FUNC(Py_ssize_t) PyLong_AsNativeBytes(PyObject* v, void* buffer,
+    Py_ssize_t n_bytes, int endianness);
+
+/* PyLong_FromNativeBytes: Create an int value from a native integer
+   n_bytes is the number of bytes to read from the buffer. Passing 0 will
+   always produce the zero int.
+   PyLong_FromUnsignedNativeBytes always produces a non-negative int.
+   endianness is -1 for native endian, 0 for big endian or 1 for little.
+
+   Returns the int object, or NULL with an exception set. */
+PyAPI_FUNC(PyObject*) PyLong_FromNativeBytes(const void* buffer, size_t n_bytes,
+    int endianness);
+PyAPI_FUNC(PyObject*) PyLong_FromUnsignedNativeBytes(const void* buffer,
+    size_t n_bytes, int endianness);
+
 PyAPI_FUNC(int) PyUnstable_Long_IsCompact(const PyLongObject* op);
 PyAPI_FUNC(Py_ssize_t) PyUnstable_Long_CompactValue(const PyLongObject* op);
 
@@ -50,7 +84,7 @@ PyAPI_FUNC(PyObject *) _PyLong_FromByteArray(
 */
 PyAPI_FUNC(int) _PyLong_AsByteArray(PyLongObject* v,
     unsigned char* bytes, size_t n,
-    int little_endian, int is_signed);
+    int little_endian, int is_signed, int with_exceptions);
 
 /* For use by the gcd function in mathmodule.c */
 PyAPI_FUNC(PyObject *) _PyLong_GCD(PyObject *, PyObject *);