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.