nptl/pt-system.c

   1 /* ABI compatibility for 'system' symbol in libpthread ABI.
   2    Copyright (C) 2002-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <stdlib.h>
  21 #include <shlib-compat.h>
  22
  23 /* libpthread once had its own 'system', though there was no apparent
  24    reason for it.  There is no use in having a separate symbol in
  25    libpthread, but the historical ABI requires it.  For static linking,
  26    there is no need to provide anything here--the libc version will be
  27    linked in.  For shared library ABI compatibility, there must be a
  28    'system' symbol in libpthread.so; so we define it using IFUNC to
  29    redirect to the libc function.  */
  30
  31 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
  32
  33 # if HAVE_IFUNC
  34
  35 static __typeof (system) *
  36 __attribute__ ((used))
  37 system_resolve (void)
  38 {
  39   return &__libc_system;
  40 }
  41
  42 asm (".globl system_ifunc\n"
  43      ".type system_ifunc, %gnu_indirect_function");
  44
  45 #  ifdef HAVE_ASM_SET_DIRECTIVE
  46 asm (".set system_ifunc, system_resolve");
  47 #  else
  48 asm ("system_ifunc = system_resolve");
  49 #  endif
  50
  51 # else  /* !HAVE_IFUNC */
  52
  53 static int __attribute__ ((used))
  54 system_compat (const char *line)
  55 {
  56   return __libc_system (line);
  57 }
  58 strong_alias (system_compat, system_ifunc)
  59
  60 # endif  /* HAVE_IFUNC */
  61
  62 compat_symbol (libpthread, system_ifunc, system, GLIBC_2_0);
  63
  64 #endif