gh-85283: Add PyMem_RawMalloc() to the limited C API

Add PyMem_RawMalloc(), PyMem_RawCalloc(), PyMem_RawRealloc() and
PyMem_RawFree() to the limited C API.

These functions were added by Python 3.4 and are needed to port
stdlib extensions to the limited C API, like grp and pwd.

Author: erlend-aasland

Doc/whatsnew/3.13.rst

@@ -886,6 +886,10 @@ New Features
   (with an underscore prefix).
   (Contributed by Victor Stinner in :gh:`108014`.)
 
+* Add :c:func:`PyMem_RawMalloc`, :c:func:`PyMem_RawCalloc`,
+  :c:func:`PyMem_RawRealloc` and :c:func:`PyMem_RawFree` to the limited C API.
+  (Contributed by Victor Stinner in :gh:`85283`.)
+
 Porting to Python 3.13
 ----------------------
 

Include/cpython/pymem.h

@@ -2,12 +2,6 @@
 #  error "this header file must not be included directly"
 #endif
 
-PyAPI_FUNC(void *) PyMem_RawMalloc(size_t size);
-PyAPI_FUNC(void *) PyMem_RawCalloc(size_t nelem, size_t elsize);
-PyAPI_FUNC(void *) PyMem_RawRealloc(void *ptr, size_t new_size);
-PyAPI_FUNC(void) PyMem_RawFree(void *ptr);
-
-
 typedef enum {
     /* PyMem_RawMalloc(), PyMem_RawRealloc() and PyMem_RawFree() */
     PYMEM_DOMAIN_RAW,

Include/pymem.h

@@ -91,6 +91,15 @@ PyAPI_FUNC(void) PyMem_Free(void *ptr);
 #define PyMem_DEL(p)              PyMem_Free((p))
 
 
+// Memory allocator which doesn't require the GIL to be held.
+// Usually, it's just a thin wrapper to functions of the standard C library:
+// malloc(), calloc(), realloc() and free(). The difference is that
+// tracemalloc can track these memory allocations.
+PyAPI_FUNC(void *) PyMem_RawMalloc(size_t size);
+PyAPI_FUNC(void *) PyMem_RawCalloc(size_t nelem, size_t elsize);
+PyAPI_FUNC(void *) PyMem_RawRealloc(void *ptr, size_t new_size);
+PyAPI_FUNC(void) PyMem_RawFree(void *ptr);
+
 #ifndef Py_LIMITED_API
 #  define Py_CPYTHON_PYMEM_H
 #  include "cpython/pymem.h"

Misc/NEWS.d/next/C API/2023-08-28-17-34-10.gh-issue-85283.f1zXcc.rst

@@ -0,0 +1,3 @@
+Add :c:func:`PyMem_RawMalloc`, :c:func:`PyMem_RawCalloc`,
+:c:func:`PyMem_RawRealloc` and :c:func:`PyMem_RawFree` to the limited C API.
+Patch by Victor Stinner.