Re: HAVE_FLUSHIO

At 11:28 PM 2/17/2002 +0000, Wez Furlong wrote:

Can someone (Sascha?) refresh my memory about HAVE_FLUSHIO ?

"Sasha" != "Sascha" ;-)

I'm wondering how it will affect the php_streams implementation. This is what I recall about it: On some systems it is necessary to fflush before reading/writing if you have been fseeking. Is this true/false/slightly incorrect?

AFAIR the ANSI standard says that for files opened in read/write mode fseek should be called (for flushing) whenever your process switches from reading to writing or vice versa. Linux' glibc is smart, of course, and a problem doesn't occur there. However more compliant platforms like Solaris and BSD have trouble if you call read, write, read for example.

Should I keep a flag to track if we have just been seeking for stdio based streams and move the HAVE_FLUSHIO logic into the stdio stream implementation?

If you use buffered I/O functions and open files in rw modes - yes (??? do you need this for the streams implementation - should read the document once more). However I would strongly recommend the PHP I/O system to organize file buffering internally (something the current implementation does partially and in quite fancy way) and to use unbuffered system I/O. If I am not clear enough - drop me a note and I will try to dig out the C and PHP examples that reproduced the problem... Rgds: -- Alex

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