glibc/dlfcn/bug-dl-leaf-lib.c

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/* Make sure dlopen/dlclose are not marked as leaf functions.
Copyright (C) 2013-2015 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;
}