ls: display command line symlinks that return ELOOP

* src/ls.c (gobble_file): Ensure we lstat() a symlink
specified on the command line, if we receive ELOOP from stat().
* tests/ls/symlink-loop.sh: Add a new test.
* tests/local.mk: Reference the new test.
* NEWS: Mention the bug fix.
Fixes https://bugs.gnu.org/63931

NEWS

@@ -18,6 +18,10 @@ GNU coreutils NEWS                                    -*- outline -*-
   Previously such file names would have caused the strip process to fail.
   [This bug was present in "the beginning".]
 
+  ls now shows symlinks specified on the command line that can't be traversed.
+  Previously a "Too many levels of symbolic links" diagnostic was given.
+  [This bug was present in "the beginning".]
+
   'pr --length=1 --double-space' no longer enters an infinite loop.
   [This bug was present in "the beginning".]
 

src/ls.c

@@ -3480,7 +3480,7 @@ gobble_file (char const *name, enum filetype type, ino_t inode,
                 break;
 
               need_lstat = (err < 0
-                            ? errno == ENOENT
+                            ? (errno == ENOENT || errno == ELOOP)
                             : ! S_ISDIR (f->stat.st_mode));
               if (!need_lstat)
                 break;

tests/local.mk

@@ -643,6 +643,7 @@ all_tests =					\
   tests/ls/stat-free-color.sh			\
   tests/ls/stat-free-symlinks.sh		\
   tests/ls/stat-vs-dirent.sh			\
+  tests/ls/symlink-loop.sh			\
   tests/ls/symlink-quote.sh			\
   tests/ls/symlink-slash.sh			\
   tests/ls/time-style-diag.sh			\

tests/ls/symlink-loop.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+# Exercise ls symlink ELOOP handling
+
+# Copyright (C) 2023 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program 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 General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ ls
+
+ln -s loop loop || framework_failure_
+cat loop >/dev/null 2>&1 && skip_ 'symlink loops not detected'
+
+# With coreutils <= 9.3 we would dereference symlinks on the command line
+# and thus fail to display a symlink that could not be traversed.
+ls loop || fail=1
+ls -l loop || fail=1
+ls -l --color=always loop || fail=1
+
+# Ensure these still fail
+returns_ 2 ls -H loop || fail=1
+returns_ 2 ls -L loop || fail=1
+
+Exit $fail