nptl/pt-fork.c

   1 /* ABI compatibility for 'fork' symbol in libpthread ABI.
   2    Copyright (C) 2002-2016 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 <unistd.h>
  21 #include <shlib-compat.h>
  22
  23 /* libpthread once had its own fork, though there was no apparent reason
  24    for it.  There is no use in having a separate symbol in libpthread, but
  25    the historical ABI requires it.  For static linking, there is no need to
  26    provide anything here--the libc version will be linked in.  For shared
  27    library ABI compatibility, there must be __fork and fork symbols in
  28    libpthread.so; so we define them using IFUNC to redirect to the libc
  29    function.  */
  30
  31 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
  32
  33 # if HAVE_IFUNC
  34
  35 static __typeof (fork) *
  36 __attribute__ ((used))
  37 fork_resolve (void)
  38 {
  39   return &__libc_fork;
  40 }
  41
  42 #  ifdef HAVE_ASM_SET_DIRECTIVE
  43 #   define DEFINE_FORK(name) \
  44   asm (".set " #name ", fork_resolve\n" \
  45        ".globl " #name "\n" \
  46        ".type " #name ", %gnu_indirect_function");
  47 #  else
  48 #   define DEFINE_FORK(name) \
  49   asm (#name " = fork_resolve\n" \
  50        ".globl " #name "\n" \
  51        ".type " #name ", %gnu_indirect_function");
  52 #  endif
  53
  54 # else  /* !HAVE_IFUNC */
  55
  56 static pid_t __attribute__ ((used))
  57 fork_compat (void)
  58 {
  59   return __libc_fork ();
  60 }
  61
  62 # define DEFINE_FORK(name) strong_alias (fork_compat, name)
  63
  64 # endif  /* HAVE_IFUNC */
  65
  66 DEFINE_FORK (fork_ifunc)
  67 compat_symbol (libpthread, fork_ifunc, fork, GLIBC_2_0);
  68
  69 DEFINE_FORK (__fork_ifunc)
  70 compat_symbol (libpthread, __fork_ifunc, __fork, GLIBC_2_0);
  71
  72 #endif