glibc/sysdeps/unix/configure.in

sinclude(./aclocal.m4)dnl Autoconf lossage.
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc.
# This file is part of the GNU C Library.

# The GNU C Library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Library General Public License
# as published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.

# The GNU C Library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Library General Public License for more details.

# You should have received a copy of the GNU Library General Public
# License along with the GNU C Library; see the file COPYING.LIB.  If
# not, write to the Free Software Foundation, Inc., 675 Mass Ave,
# Cambridge, MA 02139, USA.

dnl configure fragment for Unix-based systems.  This is processed by Autoconf,
dnl but we just use the AC_MSG_* macros.  This file is sourced by the
dnl top-level configure script.  Note that we use the prefix `unix_' on all
dnl shell variables here, to avoid conflicting with any variables the
dnl top-level script might be using.

sysincludedir=/usr/include # XXX

# Find the <syscall.h> file we will be using, or something like it.
unix_found=
for unix_dir in $sysnames; do
  if test -r $sysdep_dir/$unix_dir/syscall.h; then
    unix_found=$unix_dir
    break
  fi
done
if test $unix_found = stub; then
  # XXX This list of possibilities duplicates the list in Makefile.
  for try in sys.s sys/sys.s sys.S sys/sys.S syscall.h sys/syscall.h; do
    if test -r $sysincludedir/$try; then
      unix_syscall_h=$sysincludedir/$try
      break
    fi
  done
else
  unix_syscall_h=$sysdep_dir/$unix_dir/syscall.h
fi

test -n "$unix_syscall_h" && {

# Where to put the .S files we write.
if test "`pwd`" = "`(cd $srcdir; pwd)`"; then
  unix_generated_dirpfx=sysdeps/unix/
else
  # We are running in a separate build directory.
  unix_generated_dirpfx=
fi

# This variable will collect the names of the files we create.
unix_generated=
unix_srcs=
unix_dests=

# These several functions are system calls on Unix systems which have them.
# The details of these calls are universal enough that if a system's
# <syscall.h> defines the system call number, we know that the simple
# system call implementations in unix/common will be sufficient.

for unix_function in \
  dup2 lstat mkdir rmdir readlink symlink rename swapon \
  access select getgroups setgroups \
  getitimer setitimer \
  getdomainname:getdomain=bsd/bsd4.4 \
  setdomainname:setdomain=bsd/bsd4.4 \
  fchdir=bsd/bsd4.4 \
  profil=bsd readv=bsd writev=bsd \
  getpriority setpriority \
  getrlimit setrlimit
do

  # $unix_function  =>	$unix_syscall		$unix_srcname
  #	CALL			CALL			CALL
  #	CALL/NAME		CALL			NAME
  unix_srcname=
  unix_srcdir=common
  eval "unix_syscall=`echo $unix_function | \
		      sed -e 's@=\(.*\)$@ unix_srcdir=\1@' \
			  -e 's@:\(.*\)@ unix_srcname=\1@'`"
  test -z "$unix_srcname" && unix_srcname=$unix_syscall

  unix_implementor=none
  for unix_dir in $sysnames; do
    if test -r $sysdep_dir/$unix_dir/${unix_srcname}.c ||
       test -r $sysdep_dir/$unix_dir/${unix_srcname}.S ||
       test -r $sysdep_dir/$unix_dir/${unix_srcname}.s; then
      unix_implementor=$unix_dir
      break
    fi
  done

  case $unix_syscall in
  mkdir|rmdir) 
    # mkdir and rmdir have implementations in unix/sysv, but
    # the simple syscall versions are preferable if available.
    test $unix_implementor = unix/sysv && unix_implementor=generic
    ;;
  esac

  case $unix_implementor in
  none|stub|generic|posix)
    # The chosen implementation of ${unix_syscall} is a boring one.
    # We want to use the unix/common implementation instead iff
    # ${unix_syscall} appears in <syscall.h>.
    AC_MSG_CHECKING(for ${unix_syscall} system call)
changequote(,)dnl We need to use [ and ] for real now.
    if grep -i "[ 	_]${unix_syscall}[ 	]" $unix_syscall_h >/dev/null
changequote([,])dnl Back to Autoconf land.
    then
      # It does seem to be present in <syscall.h>.
      AC_MSG_RESULT(yes)
      unix_dests="$unix_dests ${unix_generated_dirpfx}${unix_srcname}.S"
      unix_srcs="$unix_srcs sysdeps/unix/${unix_srcdir}/${unix_srcname}.S"
      unix_generated="$unix_generated $unix_generated_dirpfx${unix_srcname}.S"
    else
      AC_MSG_RESULT(no)
    fi
  ;;
  *) ;;
  esac

done

# Autoconf magic in the top-level configure.in causes config.status to
# actually make the links.
libc_link_dests="$libc_link_dests $unix_dests"
libc_link_sources="$libc_link_sources $unix_srcs"

# Store the list of files we created in config.make; Makefile uses it.
test -n "$unix_generated" && config_vars="$config_vars
unix-generated := \$(addprefix \$(objpfx),${unix_generated})"

}