New files from gnulib.

Fixes: debbugs:12632

13 files changed, 1328 insertions, 0 deletions

diff --git a/lib/at-func.c b/lib/at-func.c
new file mode 100644
index 00000000000..481eea475a1
--- /dev/null
+++ b/lib/at-func.c
@@ -0,0 +1,146 @@
+/* Define at-style functions like fstatat, unlinkat, fchownat, etc.
+   Copyright (C) 2006, 2009-2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* written by Jim Meyering */
+
+#include "dosname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+
+#ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD
+# include <errno.h>
+# ifndef ENOTSUP
+#  define ENOTSUP EINVAL
+# endif
+#else
+# include "openat.h"
+# include "openat-priv.h"
+# include "save-cwd.h"
+#endif
+
+#ifdef AT_FUNC_USE_F1_COND
+# define CALL_FUNC(F)                           \
+  (flag == AT_FUNC_USE_F1_COND                  \
+    ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS)     \
+    : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
+# define VALIDATE_FLAG(F)                       \
+  if (flag & ~AT_FUNC_USE_F1_COND)              \
+    {                                           \
+      errno = EINVAL;                           \
+      return FUNC_FAIL;                         \
+    }
+#else
+# define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
+# define VALIDATE_FLAG(F) /* empty */
+#endif
+
+#ifdef AT_FUNC_RESULT
+# define FUNC_RESULT AT_FUNC_RESULT
+#else
+# define FUNC_RESULT int
+#endif
+
+#ifdef AT_FUNC_FAIL
+# define FUNC_FAIL AT_FUNC_FAIL
+#else
+# define FUNC_FAIL -1
+#endif
+
+/* Call AT_FUNC_F1 to operate on FILE, which is in the directory
+   open on descriptor FD.  If AT_FUNC_USE_F1_COND is defined to a value,
+   AT_FUNC_POST_FILE_PARAM_DECLS must include a parameter named flag;
+   call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
+   AT_FUNC_USE_F1_COND.  Return int and fail with -1 unless AT_FUNC_RESULT
+   or AT_FUNC_FAIL are defined.  If possible, do it without changing the
+   working directory.  Otherwise, resort to using save_cwd/fchdir,
+   then AT_FUNC_F?/restore_cwd.  If either the save_cwd or the restore_cwd
+   fails, then give a diagnostic and exit nonzero.  */
+FUNC_RESULT
+AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
+{
+  VALIDATE_FLAG (flag);
+
+  if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
+    return CALL_FUNC (file);
+
+#ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD
+  errno = ENOTSUP;
+  return FUNC_FAIL;
+#else
+  {
+  /* Be careful to choose names unlikely to conflict with
+     AT_FUNC_POST_FILE_PARAM_DECLS.  */
+  struct saved_cwd saved_cwd;
+  int saved_errno;
+  FUNC_RESULT err;
+
+  {
+    char proc_buf[OPENAT_BUFFER_SIZE];
+    char *proc_file = openat_proc_name (proc_buf, fd, file);
+    if (proc_file)
+      {
+        FUNC_RESULT proc_result = CALL_FUNC (proc_file);
+        int proc_errno = errno;
+        if (proc_file != proc_buf)
+          free (proc_file);
+        /* If the syscall succeeds, or if it fails with an unexpected
+           errno value, then return right away.  Otherwise, fall through
+           and resort to using save_cwd/restore_cwd.  */
+        if (FUNC_FAIL != proc_result)
+          return proc_result;
+        if (! EXPECTED_ERRNO (proc_errno))
+          {
+            errno = proc_errno;
+            return proc_result;
+          }
+      }
+  }
+
+  if (save_cwd (&saved_cwd) != 0)
+    openat_save_fail (errno);
+  if (0 <= fd && fd == saved_cwd.desc)
+    {
+      /* If saving the working directory collides with the user's
+         requested fd, then the user's fd must have been closed to
+         begin with.  */
+      free_cwd (&saved_cwd);
+      errno = EBADF;
+      return FUNC_FAIL;
+    }
+
+  if (fchdir (fd) != 0)
+    {
+      saved_errno = errno;
+      free_cwd (&saved_cwd);
+      errno = saved_errno;
+      return FUNC_FAIL;
+    }
+
+  err = CALL_FUNC (file);
+  saved_errno = (err == FUNC_FAIL ? errno : 0);
+
+  if (restore_cwd (&saved_cwd) != 0)
+    openat_restore_fail (errno);
+
+  free_cwd (&saved_cwd);
+
+  if (saved_errno)
+    errno = saved_errno;
+  return err;
+  }
+#endif
+}
+#undef CALL_FUNC
+#undef FUNC_RESULT
+#undef FUNC_FAIL
diff --git a/lib/euidaccess.c b/lib/euidaccess.c
new file mode 100644
index 00000000000..ca2ceca5d22
--- /dev/null
+++ b/lib/euidaccess.c
@@ -0,0 +1,221 @@
+/* euidaccess -- check if effective user id can access file
+
+   Copyright (C) 1990-1991, 1995, 1998, 2000, 2003-2006, 2008-2012 Free
+   Software Foundation, Inc.
+
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by David MacKenzie and Torbjorn Granlund.
+   Adapted for GNU C library by Roland McGrath.  */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
+
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "root-uid.h"
+
+#if HAVE_LIBGEN_H
+# include <libgen.h>
+#endif
+
+#include <errno.h>
+#ifndef __set_errno
+# define __set_errno(val) errno = (val)
+#endif
+
+#if defined EACCES && !defined EACCESS
+# define EACCESS EACCES
+#endif
+
+#ifndef F_OK
+# define F_OK 0
+# define X_OK 1
+# define W_OK 2
+# define R_OK 4
+#endif
+
+
+#ifdef _LIBC
+
+# define access __access
+# define getuid __getuid
+# define getgid __getgid
+# define geteuid __geteuid
+# define getegid __getegid
+# define group_member __group_member
+# define euidaccess __euidaccess
+# undef stat
+# define stat stat64
+
+#endif
+
+/* Return 0 if the user has permission of type MODE on FILE;
+   otherwise, return -1 and set 'errno'.
+   Like access, except that it uses the effective user and group
+   id's instead of the real ones, and it does not always check for read-only
+   file system, text busy, etc.  */
+
+int
+euidaccess (const char *file, int mode)
+{
+#if HAVE_FACCESSAT                   /* glibc, AIX 7, Solaris 11, Cygwin 1.7 */
+  return faccessat (AT_FDCWD, file, mode, AT_EACCESS);
+#elif defined EFF_ONLY_OK               /* IRIX, OSF/1, Interix */
+  return access (file, mode | EFF_ONLY_OK);
+#elif defined ACC_SELF                  /* AIX */
+  return accessx (file, mode, ACC_SELF);
+#elif HAVE_EACCESS                      /* FreeBSD */
+  return eaccess (file, mode);
+#else       /* Mac OS X, NetBSD, OpenBSD, HP-UX, Solaris, Cygwin, mingw, BeOS */
+
+  uid_t uid = getuid ();
+  gid_t gid = getgid ();
+  uid_t euid = geteuid ();
+  gid_t egid = getegid ();
+  struct stat stats;
+
+# if HAVE_DECL_SETREGID && PREFER_NONREENTRANT_EUIDACCESS
+
+  /* Define PREFER_NONREENTRANT_EUIDACCESS 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.  */
+
+  if (mode == F_OK)
+    return stat (file, &stats);
+  else
+    {
+      int result;
+      int saved_errno;
+
+      if (uid != euid)
+        setreuid (euid, uid);
+      if (gid != egid)
+        setregid (egid, gid);
+
+      result = access (file, mode);
+      saved_errno = errno;
+
+      /* Restore them.  */
+      if (uid != euid)
+        setreuid (uid, euid);
+      if (gid != egid)
+        setregid (gid, egid);
+
+      errno = saved_errno;
+      return result;
+    }
+
+# else
+
+  /* The following code assumes the traditional Unix model, and is not
+     correct on systems that have ACLs or the like.  However, it's
+     better than nothing, and it is reentrant.  */
+
+  unsigned int granted;
+  if (uid == euid && gid == egid)
+    /* If we are not set-uid or set-gid, access does the same.  */
+    return access (file, mode);
+
+  if (stat (file, &stats) != 0)
+    return -1;
+
+  /* The super-user can read and write any file, and execute any file
+     that anyone can execute.  */
+  if (euid == ROOT_UID
+      && ((mode & X_OK) == 0
+          || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
+    return 0;
+
+  /* Convert the mode to traditional form, clearing any bogus bits.  */
+  if (R_OK == 4 && W_OK == 2 && X_OK == 1 && F_OK == 0)
+    mode &= 7;
+  else
+    mode = ((mode & R_OK ? 4 : 0)
+            + (mode & W_OK ? 2 : 0)
+            + (mode & X_OK ? 1 : 0));
+
+  if (mode == 0)
+    return 0;                   /* The file exists.  */
+
+  /* Convert the file's permission bits to traditional form.  */
+  if (S_IRUSR == (4 << 6) && S_IWUSR == (2 << 6) && S_IXUSR == (1 << 6)
+      && S_IRGRP == (4 << 3) && S_IWGRP == (2 << 3) && S_IXGRP == (1 << 3)
+      && S_IROTH == (4 << 0) && S_IWOTH == (2 << 0) && S_IXOTH == (1 << 0))
+    granted = stats.st_mode;
+  else
+    granted = ((stats.st_mode & S_IRUSR ? 4 << 6 : 0)
+               + (stats.st_mode & S_IWUSR ? 2 << 6 : 0)
+               + (stats.st_mode & S_IXUSR ? 1 << 6 : 0)
+               + (stats.st_mode & S_IRGRP ? 4 << 3 : 0)
+               + (stats.st_mode & S_IWGRP ? 2 << 3 : 0)
+               + (stats.st_mode & S_IXGRP ? 1 << 3 : 0)
+               + (stats.st_mode & S_IROTH ? 4 << 0 : 0)
+               + (stats.st_mode & S_IWOTH ? 2 << 0 : 0)
+               + (stats.st_mode & S_IXOTH ? 1 << 0 : 0));
+
+  if (euid == stats.st_uid)
+    granted >>= 6;
+  else if (egid == stats.st_gid || group_member (stats.st_gid))
+    granted >>= 3;
+
+  if ((mode & ~granted) == 0)
+    return 0;
+  __set_errno (EACCESS);
+  return -1;
+
+# endif
+#endif
+}
+#undef euidaccess
+#ifdef weak_alias
+weak_alias (__euidaccess, euidaccess)
+#endif
+
+#ifdef TEST
+# include <error.h>
+# include <stdio.h>
+# include <stdlib.h>
+
+char *program_name;
+
+int
+main (int argc, char **argv)
+{
+  char *file;
+  int mode;
+  int err;
+
+  program_name = argv[0];
+  if (argc < 3)
+    abort ();
+  file = argv[1];
+  mode = atoi (argv[2]);
+
+  err = euidaccess (file, mode);
+  printf ("%d\n", err);
+  if (err != 0)
+    error (0, errno, "%s", file);
+  exit (0);
+}
+#endif
diff --git a/lib/faccessat.c b/lib/faccessat.c
new file mode 100644
index 00000000000..d11a3efaad6
--- /dev/null
+++ b/lib/faccessat.c
@@ -0,0 +1,45 @@
+/* Check the access rights of a file relative to an open directory.
+   Copyright (C) 2009-2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* written by Eric Blake */
+
+#include <config.h>
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#ifndef HAVE_ACCESS
+/* Mingw lacks access, but it also lacks real vs. effective ids, so
+   the gnulib euidaccess module is good enough.  */
+# undef access
+# define access euidaccess
+#endif
+
+/* Invoke access or euidaccess on file, FILE, using mode MODE, in the directory
+   open on descriptor FD.  If possible, do it without changing the
+   working directory.  Otherwise, resort to using save_cwd/fchdir, then
+   (access|euidaccess)/restore_cwd.  If either the save_cwd or the
+   restore_cwd fails, then give a diagnostic and exit nonzero.
+   Note that this implementation only supports AT_EACCESS, although some
+   native versions also support AT_SYMLINK_NOFOLLOW.  */
+
+#define AT_FUNC_NAME faccessat
+#define AT_FUNC_F1 euidaccess
+#define AT_FUNC_F2 access
+#define AT_FUNC_USE_F1_COND AT_EACCESS
+#define AT_FUNC_POST_FILE_PARAM_DECLS , int mode, int flag
+#define AT_FUNC_POST_FILE_ARGS        , mode
+#include "at-func.c"
diff --git a/lib/fcntl.in.h b/lib/fcntl.in.h
new file mode 100644
index 00000000000..5fdac2313d0
--- /dev/null
+++ b/lib/fcntl.in.h
@@ -0,0 +1,347 @@
+/* Like <fcntl.h>, but with non-working flags defined to 0.
+
+   Copyright (C) 2006-2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* written by Paul Eggert */
+
+#if __GNUC__ >= 3
+@PRAGMA_SYSTEM_HEADER@
+#endif
+@PRAGMA_COLUMNS@
+
+#if defined __need_system_fcntl_h
+/* Special invocation convention.  */
+
+/* Needed before <sys/stat.h>.
+   May also define off_t to a 64-bit type on native Windows.  */
+#include <sys/types.h>
+/* On some systems other than glibc, <sys/stat.h> is a prerequisite of
+   <fcntl.h>.  On glibc systems, we would like to avoid namespace pollution.
+   But on glibc systems, <fcntl.h> includes <sys/stat.h> inside an
+   extern "C" { ... } block, which leads to errors in C++ mode with the
+   overridden <sys/stat.h> from gnulib.  These errors are known to be gone
+   with g++ version >= 4.3.  */
+#if !(defined __GLIBC__ || defined __UCLIBC__) || (defined __cplusplus && defined GNULIB_NAMESPACE && !(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
+# include <sys/stat.h>
+#endif
+#@INCLUDE_NEXT@ @NEXT_FCNTL_H@
+
+#else
+/* Normal invocation convention.  */
+
+#ifndef _@GUARD_PREFIX@_FCNTL_H
+
+/* Needed before <sys/stat.h>.
+   May also define off_t to a 64-bit type on native Windows.  */
+#include <sys/types.h>
+/* On some systems other than glibc, <sys/stat.h> is a prerequisite of
+   <fcntl.h>.  On glibc systems, we would like to avoid namespace pollution.
+   But on glibc systems, <fcntl.h> includes <sys/stat.h> inside an
+   extern "C" { ... } block, which leads to errors in C++ mode with the
+   overridden <sys/stat.h> from gnulib.  These errors are known to be gone
+   with g++ version >= 4.3.  */
+#if !(defined __GLIBC__ || defined __UCLIBC__) || (defined __cplusplus && defined GNULIB_NAMESPACE && !(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
+# include <sys/stat.h>
+#endif
+/* The include_next requires a split double-inclusion guard.  */
+#@INCLUDE_NEXT@ @NEXT_FCNTL_H@
+
+#ifndef _@GUARD_PREFIX@_FCNTL_H
+#define _@GUARD_PREFIX@_FCNTL_H
+
+#ifndef __GLIBC__ /* Avoid namespace pollution on glibc systems.  */
+# include <unistd.h>
+#endif
+
+/* Native Windows platforms declare open(), creat() in <io.h>.  */
+#if (@GNULIB_OPEN@ || defined GNULIB_POSIXCHECK) \
+    && ((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)
+# include <io.h>
+#endif
+
+
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_ARG_NONNULL is copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
+
+/* Declare overridden functions.  */
+
+#if @GNULIB_FCNTL@
+# if @REPLACE_FCNTL@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef fcntl
+#   define fcntl rpl_fcntl
+#  endif
+_GL_FUNCDECL_RPL (fcntl, int, (int fd, int action, ...));
+_GL_CXXALIAS_RPL (fcntl, int, (int fd, int action, ...));
+# else
+#  if !@HAVE_FCNTL@
+_GL_FUNCDECL_SYS (fcntl, int, (int fd, int action, ...));
+#  endif
+_GL_CXXALIAS_SYS (fcntl, int, (int fd, int action, ...));
+# endif
+_GL_CXXALIASWARN (fcntl);
+#elif defined GNULIB_POSIXCHECK
+# undef fcntl
+# if HAVE_RAW_DECL_FCNTL
+_GL_WARN_ON_USE (fcntl, "fcntl is not always POSIX compliant - "
+                 "use gnulib module fcntl for portability");
+# endif
+#endif
+
+#if @GNULIB_OPEN@
+# if @REPLACE_OPEN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef open
+#   define open rpl_open
+#  endif
+_GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
+                             _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
+# else
+_GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
+# endif
+/* On HP-UX 11, in C++ mode, open() is defined as an inline function with a
+   default argument.  _GL_CXXALIASWARN does not work in this case.  */
+# if !defined __hpux
+_GL_CXXALIASWARN (open);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef open
+/* Assume open is always declared.  */
+_GL_WARN_ON_USE (open, "open is not always POSIX compliant - "
+                 "use gnulib module open for portability");
+#endif
+
+#if @GNULIB_OPENAT@
+# if @REPLACE_OPENAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef openat
+#   define openat rpl_openat
+#  endif
+_GL_FUNCDECL_RPL (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...)
+                  _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...));
+# else
+#  if !@HAVE_OPENAT@
+_GL_FUNCDECL_SYS (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...)
+                  _GL_ARG_NONNULL ((2)));
+#  endif
+_GL_CXXALIAS_SYS (openat, int,
+                  (int fd, char const *file, int flags, /* mode_t mode */ ...));
+# endif
+_GL_CXXALIASWARN (openat);
+#elif defined GNULIB_POSIXCHECK
+# undef openat
+# if HAVE_RAW_DECL_OPENAT
+_GL_WARN_ON_USE (openat, "openat is not portable - "
+                 "use gnulib module openat for portability");
+# endif
+#endif
+
+
+/* Fix up the FD_* macros, only known to be missing on mingw.  */
+
+#ifndef FD_CLOEXEC
+# define FD_CLOEXEC 1
+#endif
+
+/* Fix up the supported F_* macros.  Intentionally leave other F_*
+   macros undefined.  Only known to be missing on mingw.  */
+
+#ifndef F_DUPFD_CLOEXEC
+# define F_DUPFD_CLOEXEC 0x40000000
+/* Witness variable: 1 if gnulib defined F_DUPFD_CLOEXEC, 0 otherwise.  */
+# define GNULIB_defined_F_DUPFD_CLOEXEC 1
+#else
+# define GNULIB_defined_F_DUPFD_CLOEXEC 0
+#endif
+
+#ifndef F_DUPFD
+# define F_DUPFD 1
+#endif
+
+#ifndef F_GETFD
+# define F_GETFD 2
+#endif
+
+/* Fix up the O_* macros.  */
+
+#if !defined O_DIRECT && defined O_DIRECTIO
+/* Tru64 spells it 'O_DIRECTIO'.  */
+# define O_DIRECT O_DIRECTIO
+#endif
+
+#if !defined O_CLOEXEC && defined O_NOINHERIT
+/* Mingw spells it 'O_NOINHERIT'.  */
+# define O_CLOEXEC O_NOINHERIT
+#endif
+
+#ifndef O_CLOEXEC
+# define O_CLOEXEC 0
+#endif
+
+#ifndef O_DIRECT
+# define O_DIRECT 0
+#endif
+
+#ifndef O_DIRECTORY
+# define O_DIRECTORY 0
+#endif
+
+#ifndef O_DSYNC
+# define O_DSYNC 0
+#endif
+
+#ifndef O_EXEC
+# define O_EXEC O_RDONLY /* This is often close enough in older systems.  */
+#endif
+
+#ifndef O_IGNORE_CTTY
+# define O_IGNORE_CTTY 0
+#endif
+
+#ifndef O_NDELAY
+# define O_NDELAY 0
+#endif
+
+#ifndef O_NOATIME
+# define O_NOATIME 0
+#endif
+
+#ifndef O_NONBLOCK
+# define O_NONBLOCK O_NDELAY
+#endif
+
+/* If the gnulib module 'nonblocking' is in use, guarantee a working non-zero
+   value of O_NONBLOCK.  Otherwise, O_NONBLOCK is defined (above) to O_NDELAY
+   or to 0 as fallback.  */
+#if @GNULIB_NONBLOCKING@
+# if O_NONBLOCK
+#  define GNULIB_defined_O_NONBLOCK 0
+# else
+#  define GNULIB_defined_O_NONBLOCK 1
+#  undef O_NONBLOCK
+#  define O_NONBLOCK 0x40000000
+# endif
+#endif
+
+#ifndef O_NOCTTY
+# define O_NOCTTY 0
+#endif
+
+#ifndef O_NOFOLLOW
+# define O_NOFOLLOW 0
+#endif
+
+#ifndef O_NOLINK
+# define O_NOLINK 0
+#endif
+
+#ifndef O_NOLINKS
+# define O_NOLINKS 0
+#endif
+
+#ifndef O_NOTRANS
+# define O_NOTRANS 0
+#endif
+
+#ifndef O_RSYNC
+# define O_RSYNC 0
+#endif
+
+#ifndef O_SEARCH
+# define O_SEARCH O_RDONLY /* This is often close enough in older systems.  */
+#endif
+
+#ifndef O_SYNC
+# define O_SYNC 0
+#endif
+
+#ifndef O_TTY_INIT
+# define O_TTY_INIT 0
+#endif
+
+#if O_ACCMODE != (O_RDONLY | O_WRONLY | O_RDWR | O_EXEC | O_SEARCH)
+# undef O_ACCMODE
+# define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR | O_EXEC | O_SEARCH)
+#endif
+
+/* For systems that distinguish between text and binary I/O.
+   O_BINARY is usually declared in fcntl.h  */
+#if !defined O_BINARY && defined _O_BINARY
+  /* For MSC-compatible compilers.  */
+# define O_BINARY _O_BINARY
+# define O_TEXT _O_TEXT
+#endif
+
+#if defined __BEOS__ || defined __HAIKU__
+  /* BeOS 5 and Haiku have O_BINARY and O_TEXT, but they have no effect.  */
+# undef O_BINARY
+# undef O_TEXT
+#endif
+
+#ifndef O_BINARY
+# define O_BINARY 0
+# define O_TEXT 0
+#endif
+
+/* Fix up the AT_* macros.  */
+
+/* Work around a bug in Solaris 9 and 10: AT_FDCWD is positive.  Its
+   value exceeds INT_MAX, so its use as an int doesn't conform to the
+   C standard, and GCC and Sun C complain in some cases.  If the bug
+   is present, undef AT_FDCWD here, so it can be redefined below.  */
+#if 0 < AT_FDCWD && AT_FDCWD == 0xffd19553
+# undef AT_FDCWD
+#endif
+
+/* Use the same bit pattern as Solaris 9, but with the proper
+   signedness.  The bit pattern is important, in case this actually is
+   Solaris with the above workaround.  */
+#ifndef AT_FDCWD
+# define AT_FDCWD (-3041965)
+#endif
+
+/* Use the same values as Solaris 9.  This shouldn't matter, but
+   there's no real reason to differ.  */
+#ifndef AT_SYMLINK_NOFOLLOW
+# define AT_SYMLINK_NOFOLLOW 4096
+#endif
+
+#ifndef AT_REMOVEDIR
+# define AT_REMOVEDIR 1
+#endif
+
+/* Solaris 9 lacks these two, so just pick unique values.  */
+#ifndef AT_SYMLINK_FOLLOW
+# define AT_SYMLINK_FOLLOW 2
+#endif
+
+#ifndef AT_EACCESS
+# define AT_EACCESS 4
+#endif
+
+
+#endif /* _@GUARD_PREFIX@_FCNTL_H */
+#endif /* _@GUARD_PREFIX@_FCNTL_H */
+#endif
diff --git a/lib/getgroups.c b/lib/getgroups.c
new file mode 100644
index 00000000000..f9d36236afe
--- /dev/null
+++ b/lib/getgroups.c
@@ -0,0 +1,116 @@
+/* provide consistent interface to getgroups for systems that don't allow N==0
+
+   Copyright (C) 1996, 1999, 2003, 2006-2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* written by Jim Meyering */
+
+#include <config.h>
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#if !HAVE_GETGROUPS
+
+/* Provide a stub that fails with ENOSYS, since there is no group
+   information available on mingw.  */
+int
+getgroups (int n _GL_UNUSED, GETGROUPS_T *groups _GL_UNUSED)
+{
+  errno = ENOSYS;
+  return -1;
+}
+
+#else /* HAVE_GETGROUPS */
+
+# undef getgroups
+# ifndef GETGROUPS_ZERO_BUG
+#  define GETGROUPS_ZERO_BUG 0
+# endif
+
+/* On at least Ultrix 4.3 and NextStep 3.2, getgroups (0, NULL) always
+   fails.  On other systems, it returns the number of supplemental
+   groups for the process.  This function handles that special case
+   and lets the system-provided function handle all others.  However,
+   it can fail with ENOMEM if memory is tight.  It is unspecified
+   whether the effective group id is included in the list.  */
+
+int
+rpl_getgroups (int n, gid_t *group)
+{
+  int n_groups;
+  GETGROUPS_T *gbuf;
+  int saved_errno;
+
+  if (n < 0)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+
+  if (n != 0 || !GETGROUPS_ZERO_BUG)
+    {
+      int result;
+      if (sizeof *group == sizeof *gbuf)
+        return getgroups (n, (GETGROUPS_T *) group);
+
+      if (SIZE_MAX / sizeof *gbuf <= n)
+        {
+          errno = ENOMEM;
+          return -1;
+        }
+      gbuf = malloc (n * sizeof *gbuf);
+      if (!gbuf)
+        return -1;
+      result = getgroups (n, gbuf);
+      if (0 <= result)
+        {
+          n = result;
+          while (n--)
+            group[n] = gbuf[n];
+        }
+      saved_errno = errno;
+      free (gbuf);
+      errno == saved_errno;
+      return result;
+    }
+
+  n = 20;
+  while (1)
+    {
+      /* No need to worry about address arithmetic overflow here,
+         since the ancient systems that we're running on have low
+         limits on the number of secondary groups.  */
+      gbuf = malloc (n * sizeof *gbuf);
+      if (!gbuf)
+        return -1;
+      n_groups = getgroups (n, gbuf);
+      if (n_groups == -1 ? errno != EINVAL : n_groups < n)
+        break;
+      free (gbuf);
+      n *= 2;
+    }
+
+  saved_errno = errno;
+  free (gbuf);
+  errno = saved_errno;
+
+  return n_groups;
+}
+
+#endif /* HAVE_GETGROUPS */
diff --git a/lib/group-member.c b/lib/group-member.c
new file mode 100644
index 00000000000..5fcc7e01d0c
--- /dev/null
+++ b/lib/group-member.c
@@ -0,0 +1,119 @@
+/* group-member.c -- determine whether group id is in calling user's group list
+
+   Copyright (C) 1994, 1997-1998, 2003, 2005-2006, 2009-2012 Free Software
+   Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <stdlib.h>
+
+#include "xalloc-oversized.h"
+
+/* Most processes have no more than this many groups, and for these
+   processes we can avoid using malloc.  */
+enum { GROUPBUF_SIZE = 100 };
+
+struct group_info
+  {
+    gid_t *group;
+    gid_t groupbuf[GROUPBUF_SIZE];
+  };
+
+static void
+free_group_info (struct group_info const *g)
+{
+  if (g->group != g->groupbuf)
+    free (g->group);
+}
+
+static int
+get_group_info (struct group_info *gi)
+{
+  int n_groups = getgroups (GROUPBUF_SIZE, gi->groupbuf);
+  gi->group = gi->groupbuf;
+
+  if (n_groups < 0)
+    {
+      int n_group_slots = getgroups (0, NULL);
+      if (0 <= n_group_slots
+          && ! xalloc_oversized (n_group_slots, sizeof *gi->group))
+        {
+          gi->group = malloc (n_group_slots * sizeof *gi->group);
+          if (gi->group)
+            n_groups = getgroups (n_group_slots, gi->group);
+        }
+    }
+
+  /* In case of error, the user loses.  */
+  return n_groups;
+}
+
+/* Return non-zero if GID is one that we have in our groups list.
+   Note that the groups list is not guaranteed to contain the current
+   or effective group ID, so they should generally be checked
+   separately.  */
+
+int
+group_member (gid_t gid)
+{
+  int i;
+  int found;
+  struct group_info gi;
+  int n_groups = get_group_info (&gi);
+
+  /* Search through the list looking for GID. */
+  found = 0;
+  for (i = 0; i < n_groups; i++)
+    {
+      if (gid == gi.group[i])
+        {
+          found = 1;
+          break;
+        }
+    }
+
+  free_group_info (&gi);
+
+  return found;
+}
+
+#ifdef TEST
+
+char *program_name;
+
+int
+main (int argc, char **argv)
+{
+  int i;
+
+  program_name = argv[0];
+
+  for (i = 1; i < argc; i++)
+    {
+      gid_t gid;
+
+      gid = atoi (argv[i]);
+      printf ("%d: %s\n", gid, group_member (gid) ? "yes" : "no");
+    }
+  exit (0);
+}
+
+#endif /* TEST */
diff --git a/lib/root-uid.h b/lib/root-uid.h
new file mode 100644
index 00000000000..2379773c291
--- /dev/null
+++ b/lib/root-uid.h
@@ -0,0 +1,30 @@
+/* The user ID that always has appropriate privileges in the POSIX sense.
+
+   Copyright 2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+   Written by Paul Eggert.  */
+
+#ifndef ROOT_UID_H_
+#define ROOT_UID_H_
+
+/* The user ID that always has appropriate privileges in the POSIX sense.  */
+#ifdef __TANDEM
+# define ROOT_UID 65535
+#else
+# define ROOT_UID 0
+#endif
+
+#endif
diff --git a/lib/xalloc-oversized.h b/lib/xalloc-oversized.h
new file mode 100644
index 00000000000..ad777d8dd79
--- /dev/null
+++ b/lib/xalloc-oversized.h
@@ -0,0 +1,38 @@
+/* xalloc-oversized.h -- memory allocation size checking
+
+   Copyright (C) 1990-2000, 2003-2004, 2006-2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef XALLOC_OVERSIZED_H_
+# define XALLOC_OVERSIZED_H_
+
+# include <stddef.h>
+
+/* Return 1 if an array of N objects, each of size S, cannot exist due
+   to size arithmetic overflow.  S must be positive and N must be
+   nonnegative.  This is a macro, not a function, so that it
+   works correctly even when SIZE_MAX < N.
+
+   By gnulib convention, SIZE_MAX represents overflow in size
+   calculations, so the conservative dividend to use here is
+   SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
+   However, malloc (SIZE_MAX) fails on all known hosts where
+   sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
+   exactly-SIZE_MAX allocations on such hosts; this avoids a test and
+   branch when S is known to be 1.  */
+# define xalloc_oversized(n, s) \
+    ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
+
+#endif /* !XALLOC_OVERSIZED_H_ */
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/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])
+])