[BZ #15897] dlfcn: do not mark dlopen/dlclose as leaf functions

Since the dlopen funcs might invoke a constructor that calls a func
that is in the same compilation unit as the caller, we cannot mark
them as leaf funcs.

Similarly, dlclose might invoke a destructor that calls a func that
is in the same compilation unit as the caller.

URL: https://sourceware.org/bugzilla/show_bug.cgi?id=15897
Reportedy-by: Fabrice Bauzac <libnoon@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 71 insertions, 0 deletions

diff --git a/dlfcn/bug-dl-leaf-lib.c b/dlfcn/bug-dl-leaf-lib.c
new file mode 100644
index 0000000000..e5955422d1
--- /dev/null
+++ b/dlfcn/bug-dl-leaf-lib.c
@@ -0,0 +1,71 @@
+/* Make sure dlopen/dlclose are not marked as leaf functions.
+
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Mike Frysinger <vapier@gentoo.org>
+
+   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/>.  */
+
+/* The bug-dl-leaf.c file will call our lib_main directly.  We do this to
+   keep things simple -- no need to use --export-dynamic with the linker
+   or build the main ELF as a PIE.
+
+   The lib_main func will modify some of its state while dlopening and
+   dlclosing the bug-dl-leaf-lib-cb.so library.  The constructors and
+   destructors in that library will call back into this library to also
+   muck with state (the check_val_xxx funcs).
+
+   If dlclose/dlopen are marked as "leaf" functions, then with newer
+   versions of gcc, the state modification won't work correctly.  */
+
+#include <assert.h>
+#include <dlfcn.h>
+
+static int val = 1;
+static int called = 0;
+
+void check_val_init (void)
+{
+  called = 1;
+  assert (val == 2);
+}
+
+void check_val_fini (void)
+{
+  called = 2;
+  assert (val == 4);
+}
+
+int lib_main (void)
+{
+  int ret;
+  void *hdl;
+
+  /* Make sure the constructor sees the updated val.  */
+  val = 2;
+  hdl = dlopen ("bug-dl-leaf-lib-cb.so", RTLD_GLOBAL | RTLD_LAZY);
+  val = 3;
+  assert (hdl);
+  assert (called == 1);
+
+  /* Make sure the destructor sees the updated val.  */
+  val = 4;
+  ret = dlclose (hdl);
+  val = 5;
+  assert (ret == 0);
+  assert (called == 2);
+
+  return !val;
+}