[PATCH] iconv: Fix iconv functions not following symlinks [BZ #32339]

[Avinal Kumar]

I looked into the test case since I am new to glibc, and I can only work on
it in my spare time, it will take some time for me. Would you be willing to
move this forward? I promise I will put another patch as soon as I am able
to create a test case. I can open a Bugzilla issue to track testcase.
Thanks.

On Wed, Jun 18, 2025 at 10:11 PM Adhemerval Zanella Netto <
adhemerval.zanella@linaro.org> wrote:

>
>
> On 16/06/25 06:59, avinal.xlvii@gmail.com wrote:
> > From: Avinal Kumar <avinal.xlvii@gmail.com>
> >
> > On some file systems iconv do not follow symlinks.  This happens because
> > read_conf_file() function's directory traversal loop reject symbolic
> > links and then lstat64() call do not follow symlinks.
> >
> > This commit fixes the directory traversal loop to accept symbolic links
> > and then follow the link using stat64().
> >
> > Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>
> > ---
> > As per discussion in BZ #32339, these changes should fix the issue. I
> need help
> > testing it. It would be helpful if John can please test this on the
> particular
> > system mentioned in the bug report. Looking forward for comments.
>
> LGTM, I was wondering how hard would be to create a testcase.  We have
> --nostdlib, so it would a matter to create a temporary directory with a
> configuration and a symlink, and check if the resulting cache has the
> symlink config (which I think it would be most hard part).
>
> > ---
> >  iconv/gconv_parseconfdir.h | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/iconv/gconv_parseconfdir.h b/iconv/gconv_parseconfdir.h
> > index a7ebfd80cc..31f8f1c421 100644
> > --- a/iconv/gconv_parseconfdir.h
> > +++ b/iconv/gconv_parseconfdir.h
> > @@ -33,9 +33,10 @@
> >  # define closedir __closedir
> >  # define mempcpy __mempcpy
> >  # define struct_stat64 struct __stat64_t64
> > -# define lstat64 __lstat64_time64
> > +# define stat64_impl __stat64_time64
> >  # define feof_unlocked __feof_unlocked
> >  #else
> > +# define stat64_impl stat64
> >  # define struct_stat64 struct stat64
> >  #endif
> >
> > @@ -151,7 +152,8 @@ gconv_parseconfdir (const char *prefix, const char
> *dir, size_t dir_len)
> >        struct dirent64 *ent;
> >        while ((ent = readdir64 (confdir)) != NULL)
> >       {
> > -       if (ent->d_type != DT_REG && ent->d_type != DT_UNKNOWN)
> > +       if (ent->d_type != DT_REG && ent->d_type != DT_UNKNOWN
> > +           && ent->d_type != DT_LNK)
> >           continue;
> >
> >         size_t len = strlen (ent->d_name);
> > @@ -166,7 +168,7 @@ gconv_parseconfdir (const char *prefix, const char
> *dir, size_t dir_len)
> >               continue;
> >
> >             if (ent->d_type != DT_UNKNOWN
> > -               || (lstat64 (conf, &st) != -1 && S_ISREG (st.st_mode)))
> > +               || (stat64_impl (conf, &st) != -1 && S_ISREG
> (st.st_mode)))
> >               found |= read_conf_file (conf, dir, dir_len);
> >
> >             free (conf);
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://sourceware.org/pipermail/libc-alpha/attachments/20250625/7e6c47e9/attachment.htm>