Backport trunk's r45715: Define MAXPATHLEN to be at least PATH_MAX, if that's defined. Python uses MAXPATHLEN-sized buffers for various output-buffers (like to realpath()), and that's correct on BSD platforms, but not Linux (which uses PATH_MAX, and does not define MAXPATHLEN.) Cursory googling suggests Linux is following a newer standard than BSD, but in cases like this, who knows. Using the greater of PATH_MAX and 1024 as a fallback for MAXPATHLEN seems to be the most portable solution.

/* 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>
#include "Python.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];
	PyOS_snprintf(buf, sizeof(buf), "Unknown errno %d", err);
	return buf;
}