On Mon, Apr 04, 2005 at 12:24:26PM +0100, John Maddock wrote:
The code in question is:
# if defined(_POSIX_THREAD_SAFE_FUNCTIONS) \ && defined(_SC_THREAD_SAFE_FUNCTIONS) \ && _POSIX_THREAD_SAFE_FUNCTIONS >= 0 if ( ::sysconf( _SC_THREAD_SAFE_FUNCTIONS ) >= 0 ) { return ::readdir_r( dirp, entry, result ); } # endif
Seems like _POSIX_THREAD_SAFE_FUNCTIONS but doesn't expand to anything.
That's a common problem with the POSIX feature test macros, the workaround is to use :
(_POSIX_THREAD_SAFE_FUNCTIONS+0 >= 0)
Out of interest, why can't you just use _SC_THREAD_SAFE_FUNCTIONS if it's defined? Also, if _POSIX_THREAD_SAFE_FUNCTIONS == 0, I thought that meant *not* supported (in which case sysconf() would return -1) ? Does the test have to be >= not just > ? I'd have written it: # if defined(_SC_THREAD_SAFE_FUNCTIONS) if ( ::sysconf( _SC_THREAD_SAFE_FUNCTIONS ) > 0 ) { return ::readdir_r( dirp, entry, result ); } # endif But I didn't realise this wasn't good enough :-| Finally, readdir_r() is available on FreeBSD even though neither _POSIX_THREAD_SAFE_FUNCTIONS not _SC_THREAD_SAFE_FUNCTIONS is defined. I don't know how to test for it though, FreeBSD's sysconf() only claims to support POSIX 1990, even though some later interfaces are available. jon