Re: unlink test failure on MacOS X

[Jim Meyering]

Bruno Haible wrote:
> The workaround below impacts only MacOS platforms. I'm applying it.
> It also fixes the 'unlinkat' test failure.
>
> 2010-03-20  Bruno Haible  <address@hidden>
>
>       Work around unlink() bug on MacOS X 10.5.6.
>       * lib/unlink.c (rpl_unlink): If UNLINK_PARENT_BUG is defined, fail when
>       attempting to unlink a parent directory.
>       * m4/unlink.m4 (gl_FUNC_UNLINK): Require AC_CANONICAL_HOST. Test for
>       MacOS X 10.5 bug. If the bug is present, define UNLINK_PARENT_BUG and
>       activate for the replacement function.
>       * doc/posix-functions/unlink.texi: Mention the MacOS X 10.5 bug.
>
...
> --- m4/unlink.m4.orig Sat Mar 20 15:16:31 2010
...
> +              (umask 077 && mkdir "$tmp")
> +            }; then
> +           mkdir "$tmp/subdir"
> +           export tmp
> +           AC_RUN_IFELSE(
> +             [AC_LANG_SOURCE([[
> +                #include <stdlib.h>
> +                #include <unistd.h>
> +                int main ()
> +                {
> +                  if (chdir (getenv ("tmp")) != 0)
> +                    return 1;
> +                  return unlink ("..") == 0;
> +                }

This all looks fine.
The only question I had was why bother to create "$tmp/subdir".
At first I though it was to ensure $tmp is not empty,
but that should not matter, since the unlink is being applied to $tmp/..
which, by definition, is not empty.