dlfcn/bug-dl-leaf-lib.c

   1 /* Make sure dlopen/dlclose are not marked as leaf functions.
   2
   3    Copyright (C) 2013-2024 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 /* The bug-dl-leaf.c file will call our lib_main directly.  We do this to
  21    keep things simple -- no need to use --export-dynamic with the linker
  22    or build the main ELF as a PIE.
  23
  24    The lib_main func will modify some of its state while dlopening and
  25    dlclosing the bug-dl-leaf-lib-cb.so library.  The constructors and
  26    destructors in that library will call back into this library to also
  27    muck with state (the check_val_xxx funcs).
  28
  29    If dlclose/dlopen are marked as "leaf" functions, then with newer
  30    versions of gcc, the state modification won't work correctly.  */
  31
  32 #include <assert.h>
  33 #include <dlfcn.h>
  34
  35 static int val = 1;
  36 static int called = 0;
  37
  38 void check_val_init (void)
  39 {
  40   called = 1;
  41   assert (val == 2);
  42 }
  43
  44 void check_val_fini (void)
  45 {
  46   called = 2;
  47   assert (val == 4);
  48 }
  49
  50 int lib_main (void)
  51 {
  52   int ret __attribute__ ((unused));
  53   void *hdl;
  54
  55   /* Make sure the constructor sees the updated val.  */
  56   val = 2;
  57   hdl = dlopen ("bug-dl-leaf-lib-cb.so", RTLD_GLOBAL | RTLD_LAZY);
  58   val = 3;
  59   assert (hdl);
  60   assert (called == 1);
  61
  62   /* Make sure the destructor sees the updated val.  */
  63   val = 4;
  64   ret = dlclose (hdl);
  65   val = 5;
  66   assert (ret == 0);
  67   assert (called == 2);
  68
  69   return !val;
  70 }