new file mode 100644
--- /dev/null
+++ b/m4/largefile.m4
@@ -0,0 +1,115 @@
+#serial 4
+
+dnl By default, many hosts won't let programs access large files;
+dnl one must use special compiler options to get large-file access to work.
+dnl For more details about this brain damage please see:
+dnl http://www.sas.com/standards/large.file/x_open.20Mar96.html
+
+dnl Written by Paul Eggert <eggert@twinsun.com>.
+
+dnl Internal subroutine of AC_SYS_LARGEFILE.
+dnl AC_SYS_LARGEFILE_FLAGS(FLAGSNAME)
+AC_DEFUN(AC_SYS_LARGEFILE_FLAGS,
+  [AC_CACHE_CHECK([for $1 value to request large file support],
+     ac_cv_sys_largefile_$1,
+     [ac_cv_sys_largefile_$1=`($GETCONF LFS_$1) 2>/dev/null` || {
+	ac_cv_sys_largefile_$1=no
+	ifelse($1, CFLAGS,
+	  [case "$host_os" in
+	   # IRIX 6.2 and later require cc -n32.
+changequote(, )dnl
+	   irix6.[2-9]* | irix6.1[0-9]* | irix[7-9].* | irix[1-9][0-9]*)
+changequote([, ])dnl
+	     if test "$GCC" != yes; then
+	       ac_cv_sys_largefile_CFLAGS=-n32
+	     fi
+	     ac_save_CC="$CC"
+	     CC="$CC $ac_cv_sys_largefile_CFLAGS"
+	     AC_TRY_LINK(, , , ac_cv_sys_largefile_CFLAGS=no)
+	     CC="$ac_save_CC"
+	   esac])
+      }])])
+
+dnl Internal subroutine of AC_SYS_LARGEFILE.
+dnl AC_SYS_LARGEFILE_SPACE_APPEND(VAR, VAL)
+AC_DEFUN(AC_SYS_LARGEFILE_SPACE_APPEND,
+  [case $2 in
+   no) ;;
+   ?*)
+     case "[$]$1" in
+     '') $1=$2 ;;
+     *) $1=[$]$1' '$2 ;;
+     esac ;;
+   esac])
+
+dnl Internal subroutine of AC_SYS_LARGEFILE.
+dnl AC_SYS_LARGEFILE_MACRO_VALUE(C-MACRO, CACHE-VAR, COMMENT, CODE-TO-SET-DEFAULT)
+AC_DEFUN(AC_SYS_LARGEFILE_MACRO_VALUE,
+  [AC_CACHE_CHECK([for $1], $2,
+     [$2=no
+changequote(, )dnl
+      $4
+      for ac_flag in $ac_cv_sys_largefile_CFLAGS no; do
+	case "$ac_flag" in
+	-D$1)
+	  $2=1 ;;
+	-D$1=*)
+	  $2=`expr " $ac_flag" : '[^=]*=\(.*\)'` ;;
+	esac
+      done
+changequote([, ])dnl
+      ])
+   if test "[$]$2" != no; then
+     AC_DEFINE_UNQUOTED([$1], [$]$2, [$3])
+   fi])
+
+AC_DEFUN(AC_SYS_LARGEFILE,
+  [AC_REQUIRE([AC_CANONICAL_HOST])
+   AC_ARG_ENABLE(largefile,
+     [  --disable-largefile     omit support for large files])
+   if test "$enable_largefile" != no; then
+     AC_CHECK_TOOL(GETCONF, getconf)
+     AC_SYS_LARGEFILE_FLAGS(CFLAGS)
+     AC_SYS_LARGEFILE_FLAGS(LDFLAGS)
+     AC_SYS_LARGEFILE_FLAGS(LIBS)
+
+     for ac_flag in $ac_cv_sys_largefile_CFLAGS no; do
+       case "$ac_flag" in
+       no) ;;
+       -D_FILE_OFFSET_BITS=*) ;;
+       -D_LARGEFILE_SOURCE | -D_LARGEFILE_SOURCE=*) ;;
+       -D_LARGE_FILES | -D_LARGE_FILES=*) ;;
+       -D?* | -I?*)
+	 AC_SYS_LARGEFILE_SPACE_APPEND(CPPFLAGS, "$ac_flag") ;;
+       *)
+	 AC_SYS_LARGEFILE_SPACE_APPEND(CFLAGS, "$ac_flag") ;;
+       esac
+     done
+     AC_SYS_LARGEFILE_SPACE_APPEND(LDFLAGS, "$ac_cv_sys_largefile_LDFLAGS")
+     AC_SYS_LARGEFILE_SPACE_APPEND(LIBS, "$ac_cv_sys_largefile_LIBS")
+     AC_SYS_LARGEFILE_MACRO_VALUE(_FILE_OFFSET_BITS,
+       ac_cv_sys_file_offset_bits,
+       [Number of bits in a file offset, on hosts where this is settable.]
+       [case "$host_os" in
+	# HP-UX 10.20 and later
+	hpux10.[2-9][0-9]* | hpux1[1-9]* | hpux[2-9][0-9]*)
+	  ac_cv_sys_file_offset_bits=64 ;;
+	esac])
+     AC_SYS_LARGEFILE_MACRO_VALUE(_LARGEFILE_SOURCE,
+       ac_cv_sys_largefile_source,
+       [Define to make fseeko etc. visible, on some hosts.],
+       [case "$host_os" in
+	# HP-UX 10.20 and later
+	hpux10.[2-9][0-9]* | hpux1[1-9]* | hpux[2-9][0-9]*)
+	  ac_cv_sys_largefile_source=1 ;;
+	esac])
+     AC_SYS_LARGEFILE_MACRO_VALUE(_LARGE_FILES,
+       ac_cv_sys_large_files,
+       [Define for large files, on AIX-style hosts.],
+       [case "$host_os" in
+	# AIX 4.2 and later
+	aix4.[2-9]* | aix4.1[0-9]* | aix[5-9].* | aix[1-9][0-9]*)
+	  ac_cv_sys_large_files=1 ;;
+	esac])
+   fi
+  ])