Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!hp4nl!star.cs.vu.nl!maart
From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.unix.wizards
Subject: of course! (was: Anything faster than stat(S)? [...])
Message-ID: <4526@ski.cs.vu.nl>
Date: 13 Nov 89 22:32:29 GMT
References: <152@norsat.UUCP> <2586@unisoft.UUCP> <15769@bloom-beacon.MIT.EDU> <17264@rpp386.cactus.org>
Reply-To: maart@cs.vu.nl (Maarten Litmaath)
Organization: VU Informatica, Amsterdam
Lines: 39

In article <17264@rpp386.cactus.org> jfh@rpp386.cactus.org (John F. Haugh II) writes:
\...
\	isadir (char *path)
\	{
\		char dir[PATH_MAX];
\
\		if (access (path, 0))
\			return 0;
\
\		strcpy (dir, path);
\		strcat (dir, "/x");
\
\		errno = 0;
\		access (dir, 0);
\
\		return errno == 0 || errno == ENOENT;
\	}
\
\We know all of the initial path exists because of the first access()
\call.

Can you say `race condition'?

\And with the second access() call we can discover if the
\last component of `path' isn't a directory since errno would be ENOTDIR
\rather than ENOENT.

	isadir(char *path)
	{
		char dir[PATH_MAX];

		strcpy(dir, path);
		strcat(dir, "/.");

		return access(dir, 0);
	}
-- 
"Richard Sexton is actually an AI program (or Construct, if you will) running
on some AT&T (R) 3B" (Richard Brosseau) | maart@cs.vu.nl, mcsun!botter!maart