Xref: utzoo comp.unix.questions:6677 comp.unix.wizards:7975 comp.lang.c:9554
Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mcgill-vision!mouse
From: mouse@mcgill-vision.UUCP (der Mouse)
Newsgroups: comp.unix.questions,comp.unix.wizards,comp.lang.c
Subject: Re: Writing to A NON-Existing File in "C"
Message-ID: <1075@mcgill-vision.UUCP>
Date: 23 Apr 88 08:08:34 GMT
References: <9654@jplgodo.UUCP> <10285@steinmetz.steinmetz.ge.com> <147@obie.UUCP>
Distribution: na
Organization: McGill University, Montreal
Lines: 16
Keywords: C program, NON-EXISTING File, flushed results

In article <147@obie.UUCP>, wes@obie.UUCP (Barnacle Wes) writes:
> I'd do it slightly different.  Unless you need speed, try using
> access(2) to determine if the file is available to you, and if not
> open /dev/null for writing:
[code which is supposed to do that - I didn't check it]

This is wrong if the program might ever run setuid.  access() does not
exist to allow vanilla users to find out whether files are accessible;
it's for setuid programs to determine whether the real user can access
a file.  (It's the wrong way to do even that, because of the resulting
window, but that's another can of worms.)  The right way to find out
whether you can open a file for write is...try it!

					der Mouse

			uucp: mouse@mcgill-vision.uucp
			arpa: mouse@larry.mcrcim.mcgill.edu