--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-06-28  Jim Meyering  <meyering@redhat.com>
+
+	bootstrap: sync from coreutils
+	* build-aux/bootstrap: Honor variables like $ACLOCAL, etc.,
+	just as autoreconf does.  Verify a list of prerequisite
+	package-name,version-number pairs if defined in bootstrap.conf.
+	Refer to README-prereq, if prerequisites are not satisfied.
+
 2009-06-27  Eric Blake  <ebb9@byu.net>
 
 	tests: add test for bogus NULL definition

--- a/build-aux/bootstrap
+++ b/build-aux/bootstrap
@@ -2,7 +2,7 @@
 
 # Bootstrap this package from checked-out sources.
 
-# Copyright (C) 2003-2008 Free Software Foundation, Inc.
+# Copyright (C) 2003-2009 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
@@ -52,6 +52,9 @@
 If the file $0.conf exists in the same directory as this script, its
 contents are read as shell variables to configure the bootstrap.
 
+For build prerequisites, environment variables like \$AUTOCONF and \$AMTAR
+are honored.
+
 Running without arguments will suffice in most cases.
 "
 }
@@ -195,7 +198,7 @@
   file=$1
   str=$2
   test -f $file || touch $file
-  echo "$str" | sort -u - $file | cmp -s - $file \
+  echo "$str" | sort -u - $file | cmp - $file > /dev/null \
     || echo "$str" | sort -u - $file -o $file \
     || exit 1
 }
@@ -222,6 +225,100 @@
   done
 fi
 
+# Note this deviates from the version comparison in automake
+# in that it treats 1.5 < 1.5.0, and treats 1.4.4a < 1.4-p3a
+# but this should suffice as we won't be specifying old
+# version formats or redundant trailing .0 in bootstrap.conf.
+# If we did want full compatibility then we should probably
+# use m4_version_compare from autoconf.
+sort_ver() { # sort -V is not generally available
+  ver1="$1"
+  ver2="$2"
+
+  # split on '.' and compare each component
+  i=1
+  while : ; do
+    p1=$(echo "$ver1" | cut -d. -f$i)
+    p2=$(echo "$ver2" | cut -d. -f$i)
+    if [ ! "$p1" ]; then
+      echo "$1 $2"
+      break
+    elif [ ! "$p2" ]; then
+      echo "$2 $1"
+      break
+    elif [ ! "$p1" = "$p2" ]; then
+      if [ "$p1" -gt "$p2" ] 2>/dev/null; then # numeric comparison
+        echo "$2 $1"
+      elif [ "$p2" -gt "$p1" ] 2>/dev/null; then # numeric comparison
+        echo "$1 $2"
+      else # numeric, then lexicographic comparison
+        lp=$(printf "$p1\n$p2\n" | LANG=C sort -n | tail -n1)
+        if [ "$lp" = "$p2" ]; then
+          echo "$1 $2"
+        else
+          echo "$2 $1"
+        fi
+      fi
+      break
+    fi
+    i=$(($i+1))
+  done
+}
+
+get_version() {
+  app=$1
+
+  $app --version >/dev/null 2>&1 || return 1
+
+  $app --version 2>&1 |
+  sed -n 's/[^0-9.]*\([0-9]\{1,\}\.[.a-z0-9-]*\).*/\1/p
+	  t done
+	  d
+	  :done
+	  q'
+}
+
+check_versions() {
+  ret=0
+
+  while read app req_ver; do
+    # Honor $APP variables ($TAR, $AUTOCONF, etc.)
+    appvar=`echo $app | tr '[a-z]' '[A-Z]'`
+    test "$appvar" = TAR && appvar=AMTAR
+    eval "app=\${$appvar-$app}"
+    inst_ver=$(get_version $app)
+    if [ ! "$inst_ver" ]; then
+      echo "Error: '$app' not found" >&2
+      ret=1
+    elif [ ! "$req_ver" = "-" ]; then
+      latest_ver=$(sort_ver $req_ver $inst_ver | cut -d' ' -f2)
+      if [ ! "$latest_ver" = "$inst_ver" ]; then
+        echo "Error: '$app' version == $inst_ver is too old" >&2
+        echo "       '$app' version >= $req_ver is required" >&2
+        ret=1
+      fi
+    fi
+  done
+
+  return $ret
+}
+
+print_versions() {
+  echo "Program    Min_version"
+  echo "----------------------"
+  printf "$buildreq"
+  echo "----------------------"
+  # can't depend on column -t
+}
+
+if ! printf "$buildreq" | check_versions; then
+  test -f README-prereq &&
+  echo "Please see README-prereq for notes on obtaining these prerequisite programs:" >&2
+  echo
+  print_versions
+  exit 1
+fi
+
 echo "$0: Bootstrapping from checked-out $package sources..."
 
 # See if we can use gnulib's git-merge-changelog merge driver.
@@ -323,9 +420,9 @@
     cksum_file="$ref_po_dir/$po.s1"
     if ! test -f "$cksum_file" ||
 	! test -f "$po_dir/$po.po" ||
-	! sha1sum -c --status "$cksum_file" < "$new_po" > /dev/null; then
+	! ${SHA1SUM-sha1sum} -c --status "$cksum_file" < "$new_po" > /dev/null; then
       echo "updated $po_dir/$po.po..."
-      cp "$new_po" "$po_dir/$po.po" && sha1sum < "$new_po" > "$cksum_file"
+      cp "$new_po" "$po_dir/$po.po" && ${SHA1SUM-sha1sum} < "$new_po" > "$cksum_file"
     fi
   done
 }
@@ -487,7 +584,7 @@
       if test $file = Makefile.am; then
         copied=$copied${sep}$gnulib_mk; sep=$nl
 	remove_intl='/^[^#].*\/intl/s/^/#/;'"s!$bt_regex/!!g"
-        sed "$remove_intl" $1/$dir/$file | cmp -s - $dir/$gnulib_mk || {
+        sed "$remove_intl" $1/$dir/$file | cmp - $dir/$gnulib_mk > /dev/null || {
 	  echo "$0: Copying $1/$dir/$file to $dir/$gnulib_mk ..." &&
 	  rm -f $dir/$gnulib_mk &&
 	  sed "$remove_intl" $1/$dir/$file >$dir/$gnulib_mk
@@ -569,9 +666,9 @@
     with_gettext=no
 
 if test $with_gettext = yes; then
-  echo "$0: (cd $bt2; autopoint) ..."
+  echo "$0: (cd $bt2; ${AUTOPOINT-autopoint}) ..."
   cp configure.ac $bt2 &&
-  (cd $bt2 && autopoint && rm configure.ac) &&
+  (cd $bt2 && ${AUTOPOINT-autopoint} && rm configure.ac) &&
   slurp $bt2 $bt || exit
 fi
 rm -fr $bt $bt2 || exit
@@ -592,10 +689,10 @@
 
 for command in \
   libtool \
-  'aclocal --force -I m4' \
-  'autoconf --force' \
-  'autoheader --force' \
-  'automake --add-missing --copy --force-missing';
+  "${ACLOCAL-aclocal} --force -I m4" \
+  "${AUTOCONF-autoconf} --force" \
+  "${AUTOHEADER-autoheader} --force" \
+  "${AUTOMAKE-automake} --add-missing --copy --force-missing"
 do
   if test "$command" = libtool; then
     use_libtool=0
@@ -608,7 +705,7 @@
       && use_libtool=1
     test $use_libtool = 0 \
       && continue
-    command='libtoolize -c -f'
+    command="${LIBTOOLIZE-libtoolize} -c -f"
   fi
   echo "$0: $command ..."
   $command || exit