dlfcn/bug-dl-leaf-lib.c

   1 /* Make sure dlopen/dlclose are not marked as leaf functions.
   2
   3    Copyright (C) 2013-2020 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Mike Frysinger <vapier@gentoo.org>
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <https://www.gnu.org/licenses/>.  */
  20
  21 /* The bug-dl-leaf.c file will call our lib_main directly.  We do this to
  22    keep things simple -- no need to use --export-dynamic with the linker
  23    or build the main ELF as a PIE.
  24
  25    The lib_main func will modify some of its state while dlopening and
  26    dlclosing the bug-dl-leaf-lib-cb.so library.  The constructors and
  27    destructors in that library will call back into this library to also
  28    muck with state (the check_val_xxx funcs).
  29
  30    If dlclose/dlopen are marked as "leaf" functions, then with newer
  31    versions of gcc, the state modification won't work correctly.  */
  32
  33 #include <assert.h>
  34 #include <dlfcn.h>
  35
  36 static int val = 1;
  37 static int called = 0;
  38
  39 void check_val_init (void)
  40 {
  41   called = 1;
  42   assert (val == 2);
  43 }
  44
  45 void check_val_fini (void)
  46 {
  47   called = 2;
  48   assert (val == 4);
  49 }
  50
  51 int lib_main (void)
  52 {
  53   int ret __attribute__ ((unused));
  54   void *hdl;
  55
  56   /* Make sure the constructor sees the updated val.  */
  57   val = 2;
  58   hdl = dlopen ("bug-dl-leaf-lib-cb.so", RTLD_GLOBAL | RTLD_LAZY);
  59   val = 3;
  60   assert (hdl);
  61   assert (called == 1);
  62
  63   /* Make sure the destructor sees the updated val.  */
  64   val = 4;
  65   ret = dlclose (hdl);
  66   val = 5;
  67   assert (ret == 0);
  68   assert (called == 2);
  69
  70   return !val;
  71 }