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From: guy%gorodish@Sun.COM (Guy Harris)
Newsgroups: comp.lang.c
Subject: Re: What real non-UNIX 'C' compilers implement...
Message-ID: <29156@sun.uucp>
Date: Fri, 25-Sep-87 16:41:05 EDT
Article-I.D.: sun.29156
Posted: Fri Sep 25 16:41:05 1987
Date-Received: Sun, 27-Sep-87 07:03:42 EDT
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> Except that the O/S *manuals* follow the SVID.

*Which* OS manuals follow the SVID?  AT&T's certainly don't; in the S5R3
documentation, "read" is in section 2, and "fread" is in section 3S (same as it
ever was).

Frankly, *I*'d like to see the distinction between section 2 and section 3
erased completely, so that you don't know which library routines consist of a
little glue and a "trap" call and which don't.

Note that people *already* can't determine what is a "system call" based merely
on which manual section it's in.  If you think, for example, that "sigvec", on
systems that support it, consists merely of a little glue and a "trap" call
just because it's in section 2, think again; on Suns, it's actually a
non-trivial piece of C code maintaining its own signal vector.  This is
probably true of "signal" on a lot of machines as well.

> And except that it confuses people. "Hey, peter, how come they have read
> and fread?" "Well, fread is a library routine."

What "confuses people" here is not that this is somehow intrinsically
confusing, but that "Well, 'fread' is a library routine" is a lousy
explanation.  The difference is not "'fread' is a library routine" (in fact,
they're *both* library routines on most implementations, one just happens to be
relatively trivial - at least on UNIX systems), but "'fread' deals with
standard I/O streams and 'read' deals with UNIX file descriptors"; this
explanation may not make sense to somebody not familiar with standard I/O
streams and UNIX file descriptors, but it's not clear any *other* explanation
of this will make sense if you're not familiar with those objects.
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com