Re: ftw must *not* strip trailing slashes

[Jim Meyering]

Hi Uli,

Regarding this,

   http://sources.redhat.com/ml/bug-glibc/2003-01/msg00074.html

you asked for more details.
POSIX's section 4.11 on Pathname Resolution says in part that

  A pathname that contains at least one non-slash character and that ends
  with one or more trailing slashes shall be resolved as if a single dot
  character ('.') were appended to the pathname.

Here's the test program I described in the message listed above.

=============================
$ cat ftw-test.c
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <ftw.h>

static int
cb (const char *file, const struct stat64 *sb, int file_type, struct FTW *info)
{
  printf ("%s\n", file);
  return 0;
}

int
main (int argc, char **argv)
{
  int flags = FTW_PHYS | FTW_MOUNT | FTW_CHDIR;
  int err;
  if (argc < 2)
    exit (2);
  err = nftw64 (argv[1], cb, 30, flags);
  exit (err);
}
=============================
When linking with the version of nftw64 from GNU libc, I get this output:

  $ ./a.out slink/
  slink

When linking with the patched version (the patch in the above message),
I get this:

  $ ./a.out slink/
  slink/
  slink/x

I think the latter is more in line with the standard.
The reasoning is identical to that requiring `stat ("symlink-to-dir/", &sb)'
to dereference the symlink.

Jim

I wrote:
> Currently, ftw and nftw strip trailing slashes.
> Isn't that contrary to POSIX?  In the section on pathname resolution,
> it says that a symlink to a directory that is specified with a trailing
> slash must be treated as if `.' were appended.
>
> Accordingly, these commands
>
>   mkdir -p d/x
>   ln -s d slink
>   a.out slink/
>
> should produce output like this:
>
>   slink/
>   slink/x
...

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