nptl/pt-vfork.c

   1 /* vfork ABI-compatibility entry points for libpthread.
   2    Copyright (C) 2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <unistd.h>
  20 #include <shlib-compat.h>
  21
  22 /* libpthread used to have its own vfork implementation that differed
  23    from libc's only in having a pointless micro-optimization.  There
  24    is no longer any use to having a separate copy in libpthread, but
  25    the historical ABI requires it.  For static linking, there is no
  26    need to provide anything here--the libc version will be linked in.
  27    For shared library ABI compatibility, there must be __vfork and
  28    vfork symbols in libpthread.so; so we define them using IFUNC to
  29    redirect to the libc function.  */
  30
  31 #if (SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20) \
  32      || SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20))
  33
  34 extern __typeof (vfork) __libc_vfork;   /* Defined in libc.  */
  35
  36 # ifdef HAVE_IFUNC
  37
  38 attribute_hidden __attribute__ ((used))
  39 __typeof (vfork) *
  40 vfork_ifunc (void)
  41 {
  42   return &__libc_vfork;
  43 }
  44
  45 #  ifdef HAVE_ASM_SET_DIRECTIVE
  46 #   define DEFINE_VFORK(name) \
  47   asm (".set " #name ", vfork_ifunc\n" \
  48        ".globl " #name "\n" \
  49        ".type " #name ", %gnu_indirect_function");
  50 #  else
  51 #   define DEFINE_VFORK(name) \
  52   asm (#name " = vfork_ifunc\n" \
  53        ".globl " #name "\n" \
  54        ".type " #name ", %gnu_indirect_function");
  55 #  endif
  56
  57 # else
  58
  59 attribute_hidden
  60 pid_t
  61 vfork_compat (void)
  62 {
  63   return __libc_vfork ();
  64 }
  65
  66 # define DEFINE_VFORK(name)     weak_alias (vfork_compat, name)
  67
  68 # endif
  69 #endif
  70
  71 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20)
  72 DEFINE_VFORK (vfork)
  73 #endif
  74
  75 #if SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20)
  76 DEFINE_VFORK (__vfork)
  77 #endif