Date: Sun, 24 Jul 2016 21:49:15 +0200 From: Daniel Cegiełka <daniel.cegielka@...il.com> To: musl@...ts.openwall.com Subject: Re: dirname() / basename() - musl vs FreeBSD and OpenBSD 2016-07-24 21:21 GMT+02:00 Rich Felker <dalias@...c.org>: > On Sun, Jul 24, 2016 at 09:12:49PM +0200, Daniel Cegiełka wrote: >> Hi, >> >> I came across a very strange problem when I ports code from OpenBSD to >> musl-libc, and it seems, that a lot of problems can be caused by >> dirname(). >> >> http://pubs.opengroup.org/onlinepubs/009695399/functions/dirname.html >> >> "The dirname() function >>> may <<< modify the string pointed to by >> path, and may return a pointer to static storage that may then be >> overwritten by subsequent calls to dirname()." > > There is actually no other option for implementing this function. The > contract does not require that the argument string be a valid pathname > or have a bounded length like PATH_MAX; it operates on general > strings. And "No errors are defined", so failure is not an option. The > only way to implement this function is for it to modify its argument. Thank you for your answer. dirname() and basename() in OpenBSD compare length against PATH_MAX: http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/lib/libc/gen/dirname.c?rev=1.15 http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/lib/libc/gen/basename.c?rev=1.15 So if someone uses the code from OpenBSD/FreeBSD needs to be careful not to use the argument after dirname() or basename(). Best regards, Daniel > > Rich
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