[PATCH v2] iconv: Fix iconv functions not following symlinks [BZ #32339]

[Avinal Kumar]

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().

The test works by creating a temporary directory and placing a symbolic
link inside it that points to a configuration file.  It then runs
iconvconfig on this directory.

The test passes if iconvconfig successfully follows the symlink and
generates the cache correctly, confirming that the directory traversal
logic now properly handles symbolic links.

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>
Co-authored-by: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
---
It took some time and help to figure out how to cleanly apply the patches,
there were some whitespace issues and my first time going though a series.
Thanks Arjun for the help :)

I tested it with and without the patch and I think it is good for now. Thank
you Adhemerval for the tests.
---
 iconv/Makefile             |  6 +++++
 iconv/gconv_parseconfdir.h |  8 ++++---
 iconv/tst-iconvconfig.sh   | 48 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 3 deletions(-)
 create mode 100755 iconv/tst-iconvconfig.sh

diff --git a/iconv/Makefile b/iconv/Makefile
index 9a94a41ba4..3ed30dc89b 100644
--- a/iconv/Makefile
+++ b/iconv/Makefile
@@ -85,6 +85,7 @@ tests-special += \
 	$(objpfx)tst-iconv_prog-buffer-tiny.out \
 	$(objpfx)tst-iconv_prog-buffer.out \
 	$(objpfx)tst-iconv_prog.out \
+       $(objpfx)tst-iconvconfig.out \
 	$(objpfx)tst-translit-mchar.out \
 	# tests-special
 endif
@@ -164,3 +165,8 @@ $(objpfx)tst-iconv_prog-buffer-large.out: \
   tst-iconv_prog-buffer.sh $(objpfx)iconv_prog
 	$(BASH) $< $(common-objdir) '$(run-program-prefix)' '' '22' > $@; \
 	$(evaluate-test)
+
+$(objpfx)tst-iconvconfig.out: tst-iconvconfig.sh $(objpfx)iconvconfig
+	$(BASH) $< $(common-objdir) '$(test-wrapper-env)' \
+		'$(run-program-env)' > $@; \
+    $(evaluate-test)
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);
diff --git a/iconv/tst-iconvconfig.sh b/iconv/tst-iconvconfig.sh
new file mode 100755
index 0000000000..0b16b17f0d
--- /dev/null
+++ b/iconv/tst-iconvconfig.sh
@@ -0,0 +1,48 @@
+#!/bin/bash
+# Check if iconvconfig correctly handle config links (BZ 32339)
+# Copyright (C) 2025 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <https://www.gnu.org/licenses/>.
+
+set -e
+
+build_dir=$1
+test_wrapper_env="$2"
+run_program_env="$3"
+
+# We have to have some directories in the library path.
+LIBPATH=$build_dir:$build_dir/iconvdata
+
+ICONVCONFIG="
+$build_dir/elf/ld.so --library-path $LIBPATH $build_dir/iconv/iconvconfig
+"
+
+ICONVCONFIG="$test_wrapper_env $run_program_env $ICONVCONFIG"
+
+TIMEOUTFACTOR=${TIMEOUTFACTOR:-1}
+
+tmpdir=$(mktemp -d $build_dir/iconv/tst-iconvconfig.XXXXXX)
+#trap 'rm -fr $tmpdir' 0 1 2 3 15 EXIT
+
+touch $tmpdir/gconv-modules-extra.conf
+mkdir $tmpdir/gconv-modules.d
+cd $tmpdir/gconv-modules.d && ln -s ../gconv-modules-extra.conf . && cd -
+
+$ICONVCONFIG --nostdlib $tmpdir -o $tmpdir/gconv-modules.cache
+
+[ ! -e $tmpdir/tmpdir/gconv-modules.cache ] || exit 1
+
+exit 0
-- 
2.50.1