Date: Thu, 02 May 1996 11:14:25 -0700 From: Josh MacDonald <jmacd@CS.Berkeley.EDU> To: Poul-Henning Kamp <phk@critter.tfs.com> Cc: freebsd-hackers@freebsd.org Subject: Re: stdio problem Message-ID: <199605021814.LAA16901@paris.CS.Berkeley.EDU> In-Reply-To: Your message of "Thu, 02 May 1996 14:11:36 -0000." <3259.831046296@critter.tfs.com>
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> > close(0);
> > if(!freopen(argv[1], "r", stdin)) {
>
> doing a "close(0)" is bound to confuse the stdio library.
> don't do that.
> freopen will close the filedesriptor and thud DTRT.
>
> --
> Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team.
> http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox.
> whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, In
>c.
> Future will arrive by its own means, progress not so.
The comment below disagrees. I was kind of hoping someone familiar
with this code and ANSI and all that could explain or fix this. This
is from the top of lib/libc/stdio/freopen.c
One such program which depends on being able to freopen a descriptor
that wasn't originally open is GNU diff3. Should I report that as a
bug to its maintainer? Or, am I Wrong to exec diff3 without an open
standard input.
Who is wrong? Someone is.
-josh
/*
* Re-direct an existing, open (probably) file to some other file.
* ANSI is written such that the original file gets closed if at
* all possible, no matter what.
*/
FILE *
freopen(file, mode, fp)
const char *file, *mode;
register FILE *fp;
{
register int f;
int flags, isopen, oflags, sverrno, wantfd;
if ((flags = __sflags(mode, &oflags)) == 0) {
(void) fclose(fp);
return (NULL);
}
if (!__sdidinit)
__sinit();
/*
* There are actually programs that depend on being able to "freopen"
* descriptors that weren't originally open. Keep this from breaking.
* Remember whether the stream was open to begin with, and which file
* descriptor (if any) was associated with it. If it was attached to
* a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
* should work. This is unnecessary if it was not a Unix file.
*/
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