Tassilo Parseval <[EMAIL PROTECTED]> writes: > >My concern was with PerIO_fdopen(). I didn't know whether perl would >reuse the fd (and simply sort of wrap it in a PerlIO) or duplicate it.
There is a pod which tells you. >In case of duping, ignoring O_NONBLOCK would be bad. AFAIK a dup()ed fd inherits the non-blocking-ness along with all the other kernel level attributes like file position. > >The problem with fd-versus-FILE IO is eventually what bothers me. For Perl5.8+ you can avoid the buffering issues of that problem by just using :unix layer. >> >Going the other way (XSUB gets a glob-ref and needs FILE*/fd) isn't >> >always smooth either. >> >> >> First step is to get the IO * Perl_sv2io() does that. >> Next you get your PerlIO * - you have a choice of two the one for output >> and the one for input (often same but not for sockets or (some) ttys). >> >> Getting a FILE * isn't smooth, but we have an API for that. >> Getting a fd is just PerlIO_fileno(PerlIO *f) > >That reads amazingly simple as you describe it. Good that I can from now >on look it up for future reference. > >> >For that purpose, I made two macros: >> > >> > #ifdef _WIN32 >> > # define PerlIO_exportFILE(f,fl) ((FILE*)(f)) >> > #endif >> >> >Especially the _WIN32 branch is fishy. But it was on this list that >> >someone said that on windows a PerlIO* would just be an alias for FILE*. >> >> It was on perl5.6 - not on perl5.8. > >Bah! That means I have to change one of my modules. Quite >unsurprisingly, the branch of the code that converted a glob-ref to a >FILE* was not covered by the tests. :-( > >> > #define sv_to_file(sv) (PerlIO_exportFILE(IoIFP(sv_2io(sv)), NULL)) >> > >> That is "okay" anywhere with perl5.8+ - but please read the PODs. >> In perl5.8+ there isn't necessarily a FILE * in normal perl IO. >> So the above may have to >> >> FILE *stdio = fdopen(PerlIO_fileno(pio),mode)) > >Sigh, so not even my non-Win32 path is necessarily right. Why do you need a FILE *? Won't a PerlIO * do? - you always have one of those. IMHO you only need a FILE * for passing external C libraries that expect such a thing. > >Anyway, Nick, thanks for your patient attempts to explain this book >with 7^7 seals to me. I think I'm now able to find a way through this >muddle somehow. I will try and remember to add the essence of these discussions to the PODs.
