First step in porting MacPython modules to OSX/unix: break all references between modules except for the obj_New() and obj_Convert() routines, the PyArg_Parse and Py_BuildValue helpers. And these can now be vectored through glue routines (by defining USE_TOOLBOX_OBJECT_GLUE) which will do the necessary imports, whereupon the module's init routine will tell the glue routine about the real conversion routine address and everything is fine again.

/* PD implementation of strerror() for systems that don't have it.
   Author: Guido van Rossum, CWI Amsterdam, Oct. 1990, <guido@cwi.nl>. */

#include <stdio.h>

extern int sys_nerr;
extern char *sys_errlist[];

char *
strerror(int err)
{
	static char buf[20];
	if (err >= 0 && err < sys_nerr)
		return sys_errlist[err];
	sprintf(buf, "Unknown errno %d", err);
	return buf;
}

#ifdef macintosh
int sys_nerr = 0;
char *sys_errlist[1] = 0;
#endif