Avoid crashing in LD_DEBUG when program name is unavailable

Resolves: #15465

The program name may be unavailable if the user application tampers
with argc and argv[].  Some parts of the dynamic linker caters for
this while others don't, so this patch consolidates the check and
fallback into a single macro and updates all users.

1 files changed, 35 insertions, 0 deletions

diff --git a/elf/tst-null-argv.c b/elf/tst-null-argv.c
new file mode 100644
index 0000000000..dc242e495d
--- /dev/null
+++ b/elf/tst-null-argv.c
@@ -0,0 +1,35 @@
+/* Verify that program does not crash when LD_DEBUG is set and the program name
+   is not available.
+   Copyright (C) 2013 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
+   <http://www.gnu.org/licenses/>.  */
+
+extern void foo (void);
+
+int
+do_test (int argc, char **argv)
+{
+  argv[0] = argv[1];
+  argc--;
+
+  /* This should result in a symbol lookup, causing a volley of debug output
+     when LD_DEBUG=symbols.  */
+  foo ();
+
+  return 0;
+}
+
+#include <test-skeleton.c>