6 files changed, 371 insertions, 0 deletions

diff --git a/m4/euidaccess.m4 b/m4/euidaccess.m4
new file mode 100644
index 00000000000..2de95b88ba8
--- /dev/null
+++ b/m4/euidaccess.m4
@@ -0,0 +1,52 @@
+# euidaccess.m4 serial 15
+dnl Copyright (C) 2002-2012 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_NONREENTRANT_EUIDACCESS],
+[
+  AC_REQUIRE([gl_FUNC_EUIDACCESS])
+  AC_CHECK_DECLS([setregid])
+  AC_DEFINE([PREFER_NONREENTRANT_EUIDACCESS], [1],
+    [Define this if you prefer euidaccess to return the correct result
+     even if this would make it nonreentrant.  Define this only if your
+     entire application is safe even if the uid or gid might temporarily
+     change.  If your application uses signal handlers or threads it
+     is probably not safe.])
+])
+
+AC_DEFUN([gl_FUNC_EUIDACCESS],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+
+  dnl Persuade glibc <unistd.h> to declare euidaccess().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_FUNCS([euidaccess])
+  if test $ac_cv_func_euidaccess = no; then
+    HAVE_EUIDACCESS=0
+  fi
+])
+
+# Prerequisites of lib/euidaccess.c.
+AC_DEFUN([gl_PREREQ_EUIDACCESS], [
+  dnl Prefer POSIX faccessat over non-standard euidaccess.
+  AC_CHECK_FUNCS_ONCE([faccessat])
+  dnl Try various other non-standard fallbacks.
+  AC_CHECK_HEADERS([libgen.h])
+  AC_FUNC_GETGROUPS
+
+  # Solaris 9 and 10 need -lgen to get the eaccess function.
+  # Save and restore LIBS so -lgen isn't added to it.  Otherwise, *all*
+  # programs in the package would end up linked with that potentially-shared
+  # library, inducing unnecessary run-time overhead.
+  LIB_EACCESS=
+  AC_SUBST([LIB_EACCESS])
+  gl_saved_libs=$LIBS
+    AC_SEARCH_LIBS([eaccess], [gen],
+                   [test "$ac_cv_search_eaccess" = "none required" ||
+                    LIB_EACCESS=$ac_cv_search_eaccess])
+    AC_CHECK_FUNCS([eaccess])
+  LIBS=$gl_saved_libs
+])
diff --git a/m4/faccessat.m4 b/m4/faccessat.m4
new file mode 100644
index 00000000000..82f3b1f8dde
--- /dev/null
+++ b/m4/faccessat.m4
@@ -0,0 +1,28 @@
+# serial 6
+# See if we need to provide faccessat replacement.
+
+dnl Copyright (C) 2009-2012 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Written by Eric Blake.
+
+AC_DEFUN([gl_FUNC_FACCESSAT],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+
+  dnl Persuade glibc <unistd.h> to declare faccessat().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_FUNCS_ONCE([faccessat])
+  if test $ac_cv_func_faccessat = no; then
+    HAVE_FACCESSAT=0
+  fi
+])
+
+# Prerequisites of lib/faccessat.m4.
+AC_DEFUN([gl_PREREQ_FACCESSAT],
+[
+  AC_CHECK_FUNCS([access])
+])
diff --git a/m4/fcntl_h.m4 b/m4/fcntl_h.m4
new file mode 100644
index 00000000000..cac28aeb283
--- /dev/null
+++ b/m4/fcntl_h.m4
@@ -0,0 +1,50 @@
+# serial 15
+# Configure fcntl.h.
+dnl Copyright (C) 2006-2007, 2009-2012 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Paul Eggert.
+
+AC_DEFUN([gl_FCNTL_H],
+[
+  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+  AC_REQUIRE([gl_FCNTL_O_FLAGS])
+  gl_NEXT_HEADERS([fcntl.h])
+
+  dnl Ensure the type pid_t gets defined.
+  AC_REQUIRE([AC_TYPE_PID_T])
+
+  dnl Ensure the type mode_t gets defined.
+  AC_REQUIRE([AC_TYPE_MODE_T])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, if it is not common
+  dnl enough to be declared everywhere.
+  gl_WARN_ON_USE_PREPARE([[#include <fcntl.h>
+    ]], [fcntl openat])
+])
+
+AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_FCNTL_H_DEFAULTS],
+[
+  GNULIB_FCNTL=0;        AC_SUBST([GNULIB_FCNTL])
+  GNULIB_NONBLOCKING=0;  AC_SUBST([GNULIB_NONBLOCKING])
+  GNULIB_OPEN=0;         AC_SUBST([GNULIB_OPEN])
+  GNULIB_OPENAT=0;       AC_SUBST([GNULIB_OPENAT])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_FCNTL=1;          AC_SUBST([HAVE_FCNTL])
+  HAVE_OPENAT=1;         AC_SUBST([HAVE_OPENAT])
+  REPLACE_FCNTL=0;       AC_SUBST([REPLACE_FCNTL])
+  REPLACE_OPEN=0;        AC_SUBST([REPLACE_OPEN])
+  REPLACE_OPENAT=0;      AC_SUBST([REPLACE_OPENAT])
+])
diff --git a/m4/getgroups.m4 b/m4/getgroups.m4
new file mode 100644
index 00000000000..17473af486b
--- /dev/null
+++ b/m4/getgroups.m4
@@ -0,0 +1,107 @@
+# serial 18
+
+dnl From Jim Meyering.
+dnl A wrapper around AC_FUNC_GETGROUPS.
+
+# Copyright (C) 1996-1997, 1999-2004, 2008-2012 Free Software Foundation, Inc.
+#
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+m4_version_prereq([2.70], [] ,[
+
+# This is taken from the following Autoconf patch:
+# http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
+AC_DEFUN([AC_FUNC_GETGROUPS],
+[
+  AC_REQUIRE([AC_TYPE_GETGROUPS])dnl
+  AC_REQUIRE([AC_TYPE_SIZE_T])dnl
+  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
+  AC_CHECK_FUNC([getgroups])
+
+  # If we don't yet have getgroups, see if it's in -lbsd.
+  # This is reported to be necessary on an ITOS 3000WS running SEIUX 3.1.
+  ac_save_LIBS=$LIBS
+  if test $ac_cv_func_getgroups = no; then
+    AC_CHECK_LIB(bsd, getgroups, [GETGROUPS_LIB=-lbsd])
+  fi
+
+  # Run the program to test the functionality of the system-supplied
+  # getgroups function only if there is such a function.
+  if test $ac_cv_func_getgroups = yes; then
+    AC_CACHE_CHECK([for working getgroups], [ac_cv_func_getgroups_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+            [AC_INCLUDES_DEFAULT],
+            [[/* On Ultrix 4.3, getgroups (0, 0) always fails.  */
+              return getgroups (0, 0) == -1;]])
+         ],
+         [ac_cv_func_getgroups_works=yes],
+         [ac_cv_func_getgroups_works=no],
+         [case "$host_os" in # ((
+                    # Guess yes on glibc systems.
+            *-gnu*) ac_cv_func_getgroups_works="guessing yes" ;;
+                    # If we don't know, assume the worst.
+            *)      ac_cv_func_getgroups_works="guessing no" ;;
+          esac
+         ])
+      ])
+  else
+    ac_cv_func_getgroups_works=no
+  fi
+  case "$ac_cv_func_getgroups_works" in
+    *yes)
+      AC_DEFINE([HAVE_GETGROUPS], [1],
+        [Define to 1 if your system has a working `getgroups' function.])
+      ;;
+  esac
+  LIBS=$ac_save_LIBS
+])# AC_FUNC_GETGROUPS
+
+])
+
+AC_DEFUN([gl_FUNC_GETGROUPS],
+[
+  AC_REQUIRE([AC_TYPE_GETGROUPS])
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+  AC_FUNC_GETGROUPS
+  if test $ac_cv_func_getgroups != yes; then
+    HAVE_GETGROUPS=0
+  else
+    if test "$ac_cv_type_getgroups" != gid_t \
+       || { case "$ac_cv_func_getgroups_works" in
+              *yes) false;;
+              *) true;;
+            esac
+          }; then
+      REPLACE_GETGROUPS=1
+      AC_DEFINE([GETGROUPS_ZERO_BUG], [1], [Define this to 1 if
+        getgroups(0,NULL) does not return the number of groups.])
+    else
+      dnl Detect FreeBSD bug; POSIX requires getgroups(-1,ptr) to fail.
+      AC_CACHE_CHECK([whether getgroups handles negative values],
+        [gl_cv_func_getgroups_works],
+        [AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
+          [[int size = getgroups (0, 0);
+            gid_t *list = malloc (size * sizeof *list);
+            return getgroups (-1, list) != -1;]])],
+          [gl_cv_func_getgroups_works=yes],
+          [gl_cv_func_getgroups_works=no],
+          [case "$host_os" in
+                     # Guess yes on glibc systems.
+             *-gnu*) gl_cv_func_getgroups_works="guessing yes" ;;
+                     # If we don't know, assume the worst.
+             *)      gl_cv_func_getgroups_works="guessing no" ;;
+           esac
+          ])])
+      case "$gl_cv_func_getgroups_works" in
+        *yes) ;;
+        *) REPLACE_GETGROUPS=1 ;;
+      esac
+    fi
+  fi
+  test -n "$GETGROUPS_LIB" && LIBS="$GETGROUPS_LIB $LIBS"
+])
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 5cd278454e7..30f81b4781f 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -54,18 +54,23 @@ AC_DEFUN([gl_EARLY],
   # Code from module dtotimespec:
   # Code from module dup2:
   # Code from module environ:
+  # Code from module euidaccess:
   # Code from module execinfo:
   # Code from module extensions:
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   # Code from module extern-inline:
+  # Code from module faccessat:
+  # Code from module fcntl-h:
   # Code from module filemode:
   # Code from module fpending:
+  # Code from module getgroups:
   # Code from module getloadavg:
   # Code from module getopt-gnu:
   # Code from module getopt-posix:
   # Code from module gettext-h:
   # Code from module gettime:
   # Code from module gettimeofday:
+  # Code from module group-member:
   # Code from module ignore-value:
   # Code from module include_next:
   # Code from module intprops:
@@ -81,6 +86,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module pselect:
   # Code from module pthread_sigmask:
   # Code from module readlink:
+  # Code from module root-uid:
   # Code from module signal-h:
   # Code from module snippet/_Noreturn:
   # Code from module snippet/arg-nonnull:
@@ -122,6 +128,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module utimens:
   # Code from module verify:
   # Code from module warnings:
+  # Code from module xalloc-oversized:
 ])
 
 # This macro should be invoked from ./configure.ac, in the section
@@ -160,6 +167,14 @@ AC_DEFUN([gl_INIT],
   gl_UNISTD_MODULE_INDICATOR([environ])
   gl_EXECINFO_H
   AC_REQUIRE([gl_EXTERN_INLINE])
+  gl_FUNC_FACCESSAT
+  if test $HAVE_FACCESSAT = 0; then
+    AC_LIBOBJ([faccessat])
+    gl_PREREQ_FACCESSAT
+  fi
+  gl_MODULE_INDICATOR([faccessat])
+  gl_UNISTD_MODULE_INDICATOR([faccessat])
+  gl_FCNTL_H
   gl_FILEMODE
   gl_FUNC_FPENDING
   if test $ac_cv_func___fpending = no; then
@@ -278,18 +293,53 @@ AC_DEFUN([gl_INIT],
   gl_UNISTD_H
   gl_UTIMENS
   gl_gnulib_enabled_dosname=false
+  gl_gnulib_enabled_euidaccess=false
+  gl_gnulib_enabled_getgroups=false
   gl_gnulib_enabled_be453cec5eecf5731a274f2de7f2db36=false
+  gl_gnulib_enabled_a9786850e999ae65a836a6041e8e5ed1=false
   gl_gnulib_enabled_pathmax=false
+  gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c=false
   gl_gnulib_enabled_stat=false
   gl_gnulib_enabled_strtoll=false
   gl_gnulib_enabled_strtoull=false
   gl_gnulib_enabled_verify=false
+  gl_gnulib_enabled_682e609604ccaac6be382e4ee3a4eaec=false
   func_gl_gnulib_m4code_dosname ()
   {
     if ! $gl_gnulib_enabled_dosname; then
       gl_gnulib_enabled_dosname=true
     fi
   }
+  func_gl_gnulib_m4code_euidaccess ()
+  {
+    if ! $gl_gnulib_enabled_euidaccess; then
+      gl_FUNC_EUIDACCESS
+      if test $HAVE_EUIDACCESS = 0; then
+        AC_LIBOBJ([euidaccess])
+        gl_PREREQ_EUIDACCESS
+      fi
+      gl_UNISTD_MODULE_INDICATOR([euidaccess])
+      gl_gnulib_enabled_euidaccess=true
+      if test $HAVE_EUIDACCESS = 0; then
+        func_gl_gnulib_m4code_a9786850e999ae65a836a6041e8e5ed1
+      fi
+      func_gl_gnulib_m4code_6099e9737f757db36c47fa9d9f02e88c
+      if test $HAVE_EUIDACCESS = 0; then
+        func_gl_gnulib_m4code_stat
+      fi
+    fi
+  }
+  func_gl_gnulib_m4code_getgroups ()
+  {
+    if ! $gl_gnulib_enabled_getgroups; then
+      gl_FUNC_GETGROUPS
+      if test $HAVE_GETGROUPS = 0 || test $REPLACE_GETGROUPS = 1; then
+        AC_LIBOBJ([getgroups])
+      fi
+      gl_UNISTD_MODULE_INDICATOR([getgroups])
+      gl_gnulib_enabled_getgroups=true
+    fi
+  }
   func_gl_gnulib_m4code_be453cec5eecf5731a274f2de7f2db36 ()
   {
     if ! $gl_gnulib_enabled_be453cec5eecf5731a274f2de7f2db36; then
@@ -298,6 +348,24 @@ AC_DEFUN([gl_INIT],
       gl_gnulib_enabled_be453cec5eecf5731a274f2de7f2db36=true
     fi
   }
+  func_gl_gnulib_m4code_a9786850e999ae65a836a6041e8e5ed1 ()
+  {
+    if ! $gl_gnulib_enabled_a9786850e999ae65a836a6041e8e5ed1; then
+      gl_FUNC_GROUP_MEMBER
+      if test $HAVE_GROUP_MEMBER = 0; then
+        AC_LIBOBJ([group-member])
+        gl_PREREQ_GROUP_MEMBER
+      fi
+      gl_UNISTD_MODULE_INDICATOR([group-member])
+      gl_gnulib_enabled_a9786850e999ae65a836a6041e8e5ed1=true
+      if test $HAVE_GROUP_MEMBER = 0; then
+        func_gl_gnulib_m4code_getgroups
+      fi
+      if test $HAVE_GROUP_MEMBER = 0; then
+        func_gl_gnulib_m4code_682e609604ccaac6be382e4ee3a4eaec
+      fi
+    fi
+  }
   func_gl_gnulib_m4code_pathmax ()
   {
     if ! $gl_gnulib_enabled_pathmax; then
@@ -305,6 +373,12 @@ AC_DEFUN([gl_INIT],
       gl_gnulib_enabled_pathmax=true
     fi
   }
+  func_gl_gnulib_m4code_6099e9737f757db36c47fa9d9f02e88c ()
+  {
+    if ! $gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c; then
+      gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c=true
+    fi
+  }
   func_gl_gnulib_m4code_stat ()
   {
     if ! $gl_gnulib_enabled_stat; then
@@ -356,6 +430,18 @@ AC_DEFUN([gl_INIT],
       gl_gnulib_enabled_verify=true
     fi
   }
+  func_gl_gnulib_m4code_682e609604ccaac6be382e4ee3a4eaec ()
+  {
+    if ! $gl_gnulib_enabled_682e609604ccaac6be382e4ee3a4eaec; then
+      gl_gnulib_enabled_682e609604ccaac6be382e4ee3a4eaec=true
+    fi
+  }
+  if test $HAVE_FACCESSAT = 0; then
+    func_gl_gnulib_m4code_dosname
+  fi
+  if test $HAVE_FACCESSAT = 0; then
+    func_gl_gnulib_m4code_euidaccess
+  fi
   if test $REPLACE_GETOPT = 1; then
     func_gl_gnulib_m4code_be453cec5eecf5731a274f2de7f2db36
   fi
@@ -382,12 +468,17 @@ AC_DEFUN([gl_INIT],
   fi
   m4_pattern_allow([^gl_GNULIB_ENABLED_])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_dosname], [$gl_gnulib_enabled_dosname])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_euidaccess], [$gl_gnulib_enabled_euidaccess])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_getgroups], [$gl_gnulib_enabled_getgroups])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36], [$gl_gnulib_enabled_be453cec5eecf5731a274f2de7f2db36])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1], [$gl_gnulib_enabled_a9786850e999ae65a836a6041e8e5ed1])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_pathmax], [$gl_gnulib_enabled_pathmax])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_6099e9737f757db36c47fa9d9f02e88c], [$gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_stat], [$gl_gnulib_enabled_stat])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_strtoll], [$gl_gnulib_enabled_strtoll])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_strtoull], [$gl_gnulib_enabled_strtoull])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_verify], [$gl_gnulib_enabled_verify])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_682e609604ccaac6be382e4ee3a4eaec], [$gl_gnulib_enabled_682e609604ccaac6be382e4ee3a4eaec])
   # End of code from modules
   m4_ifval(gl_LIBSOURCES_LIST, [
     m4_syscmd([test ! -d ]m4_defn([gl_LIBSOURCES_DIR])[ ||
@@ -536,6 +627,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/alloca.in.h
   lib/allocator.c
   lib/allocator.h
+  lib/at-func.c
   lib/c-ctype.c
   lib/c-ctype.h
   lib/c-strcase.h
@@ -549,14 +641,18 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/dtoastr.c
   lib/dtotimespec.c
   lib/dup2.c
+  lib/euidaccess.c
   lib/execinfo.c
   lib/execinfo.in.h
+  lib/faccessat.c
+  lib/fcntl.in.h
   lib/filemode.c
   lib/filemode.h
   lib/fpending.c
   lib/fpending.h
   lib/ftoastr.c
   lib/ftoastr.h
+  lib/getgroups.c
   lib/getloadavg.c
   lib/getopt.c
   lib/getopt.in.h
@@ -565,6 +661,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/gettext.h
   lib/gettime.c
   lib/gettimeofday.c
+  lib/group-member.c
   lib/ignore-value.h
   lib/intprops.h
   lib/inttypes.in.h
@@ -577,6 +674,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/pselect.c
   lib/pthread_sigmask.c
   lib/readlink.c
+  lib/root-uid.h
   lib/sha1.c
   lib/sha1.h
   lib/sha256.c
@@ -618,6 +716,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/utimens.c
   lib/utimens.h
   lib/verify.h
+  lib/xalloc-oversized.h
   m4/00gnulib.m4
   m4/alloca.m4
   m4/c-strtod.m4
@@ -625,16 +724,22 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/close-stream.m4
   m4/dup2.m4
   m4/environ.m4
+  m4/euidaccess.m4
   m4/execinfo.m4
   m4/extensions.m4
   m4/extern-inline.m4
+  m4/faccessat.m4
+  m4/fcntl-o.m4
+  m4/fcntl_h.m4
   m4/filemode.m4
   m4/fpending.m4
+  m4/getgroups.m4
   m4/getloadavg.m4
   m4/getopt.m4
   m4/gettime.m4
   m4/gettimeofday.m4
   m4/gnulib-common.m4
+  m4/group-member.m4
   m4/include_next.m4
   m4/inttypes.m4
   m4/largefile.m4
diff --git a/m4/group-member.m4 b/m4/group-member.m4
new file mode 100644
index 00000000000..c393b5b1303
--- /dev/null
+++ b/m4/group-member.m4
@@ -0,0 +1,29 @@
+# serial 14
+
+# Copyright (C) 1999-2001, 2003-2007, 2009-2012 Free Software Foundation, Inc.
+
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+dnl Written by Jim Meyering
+
+AC_DEFUN([gl_FUNC_GROUP_MEMBER],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+
+  dnl Persuade glibc <unistd.h> to declare group_member().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  dnl Do this replacement check manually because I want the hyphen
+  dnl (not the underscore) in the filename.
+  AC_CHECK_FUNC([group_member], , [
+    HAVE_GROUP_MEMBER=0
+  ])
+])
+
+# Prerequisites of lib/group-member.c.
+AC_DEFUN([gl_PREREQ_GROUP_MEMBER],
+[
+  AC_REQUIRE([AC_FUNC_GETGROUPS])
+])