Re: fopen + mmap

[Andreas Schwab <schwab at suse dot de>]

Roland McGrath <roland@frob.com> writes:

|> > Are you sure that POSIX.1-1996 has this?  The C Standard has never
|> > defined fflush on input streams, and SUS2, which is based on
|> > POSIX.1-1996 IIRC, doesn't have it either.
|> 
|> I already cited the section.  It's 8.2.3(1)(g), p 213 ll 323-325:
|> 
|> 	(g) If the stream is open with a mode that allows reading and
|> 	    the underlying open file description refers to a device
|> 	    that is capable of seeking, either an fflush() shall occur
|> 	    or the stream shall be closed.
|> 
|> This is in the list of things to do on the first handle that are
|> sufficient to make the file position well-defined on the the next
|> handle used.

It only talks about a mode that _allows_ reading.  It does not make fflush
on an input stream, or an update stream that was last read, a defined
operation (you must call fclose instead to be compliant).

The whole section is about shared file descriptions, the actions to be
taken before a file descriptions may be accessed through a second handle.
It does not define the semantics of a non-shared stream.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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