Subject: bug#20006: Bash-specific performance by avoiding sed

From: Pavel Raiskup <[email-masked]>
Date: Wed, 07 Oct 2015 14:28:30 +0200

On Monday 05 of October 2015 15:28:56 Pavel Raiskup wrote:
> On Monday 05 of October 2015 09:47:05 Pavel Raiskup wrote:
> > On Monday 05 of October 2015 01:25:24 Pavel Raiskup wrote:
> > > On Monday 05 of October 2015 00:45:50 Pavel Raiskup wrote:
> > > > > should we test the size of the string first ?  i've written such raw shell 
> > > > > string parsing functions before, and once you hit a certain size (like 1k+ 
> > > > > iirc), forking out to sed is way faster, especially when running in multibyte 
> > > > > locales (like UTF8) which most people are doing nowadays.
> > > > > -mike
> > > > 
> > > > Well, that optimization would require (fast) strlen()-like construct.
> > > > Anyway, the vast majority of calls to func_quote () function will have
> > > > short ARG, and its complexity is still "just" linear.  We could optimize
> > > > later if that was a real issue.
> > > > 
> > > > I would like to propose solution based on Eric's one, without using of
> > > > '${VAR%.}' and '${VAR#.}' constructs -- sounds like this could be even
> > > > more portable while it keeps almost the same speed (if we can use += its
> > > > even faster).
> > > > 
> > > > I have yet a another patch trying to minimize option-parser overhead
> > > > (that is focused on the POV of Richard, but that needs to be cleaned up a
> > > > bit, I'll post hopefully tomorrow).
> > > > 
> > > > Any comment is welcome!
> > > 
> > > Re-attached (fixes for 'make syntax-check' and fixed one comment).
> > 
> > Hmm, one might-be-a-problem with this (catched by testsuite), when you
> > have:
> > 
> >   $ cat build-aux/test-quoting
> >   . `echo "$0" |${SED-sed} 's|[^/]*$||'`/funclib.sh
> >   # source this for "GNU m4" detection methods
> >   . `echo "$0" |${SED-sed} 's|[^/]*$||'`/extract-trace
> > 
> >   func_quote_for_eval "$@"
> >   echo "$func_quote_for_eval_result"
> > 
> > Then:
> > 
> >   $ ./build-aux/test-quoting '"a b"' # fine
> >   "\"a b\""
> > 
> >   $ ./build-aux/test-quoting '"*tool"' # broken
> >   ./build-aux/test-quoting '"*tool"'
> >   \"libtool\"
> > 
> > We would like to have an output \"*\".  I'm not aware of portable way
> > how to disable wildcard expansion in shell, and autoconf 'Shellology'
> > section haven't helped me.  In particular, the problem is here:
> > 
> >   x='a"[a-z]*"c'
> >   IFS='"'
> >   for i in $x; do # Here we wan't to disable wildcard expansion
> >     echo $i
> >   done
> > 
> > Any idea other than fallback to $sed_quote_subst in case of '*' or '['
> > exists in ARG?
> 
> Attaching two (yet to be cleaned) patches doing the optimization.  Is
> anybody able to test/comment on this particular solution?  That would be
> really appreciated.

The cleaned patches are attached.  I would like to push those very soon,
probably before weekend.  If you see any issues worth holding this change,
please let me know soon, thanks!

FWIW, some numbers (systemd.git build time, right after 'make clean'):

The old libtool v2.4.2:
  $ time make -j5
  real    2m3.163s
  user    3m54.849s
  sys     3m28.684s

The latest released libtool v2.4.6:
  $ time make -j5 LIBTOOL=/usr/bin/libtool
  real    8m24.604s
  user    9m56.977s
  sys     19m45.620s

The patched git libtool:
  $ time make -j5 LIBTOOL=~/rh/projects/libtool/libtool
  real    2m34.682s
  user    6m37.158s
  sys     2m21.123s

.. so it is (2.4.6 vs. 2.4.7~dev, user+sys) 7m23.5s vs 8m58.3s.  It's not
completely back yet but it's much better than v2.4.6.

Pavel
>From 74940e9306df18deddd11621791973df886e313a Mon Sep 17 00:00:00 2001
From: Pavel Raiskup <[email-masked]>
Date: Sun, 4 Oct 2015 21:55:03 +0200
Subject: [PATCH 1/2] libtool: mitigate the $sed_quote_subst slowdown

When it is reasonably possible, use shell implementation for
quoting.

References:
http://lists.gnu.org/archive/html/libtool/2015-03/msg00005.html
http://lists.gnu.org/archive/html/libtool/2015-02/msg00000.html
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20006

* gl/build-aux/funclib.sh (func_quote): New function that can be
used as substitution for '$SED $sed_quote_subst' call.
* build-aux/ltmain.in (func_emit_wrapper): Use func_quote instead
of '$SED $sed_quote_subst'.
(func_mode_link): Likewise.
* NEWS: Document.
* bootstrap: Sync with funclib.sh.
---
 NEWS                    |  3 +++
 bootstrap               | 56 +++++++++++++++++++++++++++++++++++++++++++++++--
 build-aux/ltmain.in     | 10 +++++----
 gl/build-aux/funclib.sh | 56 +++++++++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 117 insertions(+), 8 deletions(-)

diff --git a/NEWS b/NEWS
index a3c5b12..7c23d03 100644
--- a/NEWS
+++ b/NEWS
@@ -17,6 +17,9 @@ NEWS - list of user-visible changes between releases of GNU Libtool
   - Fix significant slowdown of libtoolize for certain projects (regression
     introduced in 2.4.3 release) caused by infinite m4 macro recursion.
 
+  - Mitigate the slowdown of libtool script (introduced in v2.4.3) caused by
+    increased number of calls to '$SED $sed_quote_subst' (bug#20006).
+
 * Noteworthy changes in release 2.4.6 (2015-02-15) [stable]
 
 ** New features:
diff --git a/bootstrap b/bootstrap
index c179f51..2649478 100755
--- a/bootstrap
+++ b/bootstrap
@@ -230,7 +230,7 @@ vc_ignore=
 
 # Source required external libraries:
 # Set a version string for this script.
-scriptversion=2015-01-20.17; # UTC
+scriptversion=2015-10-04.22; # UTC
 
 # General shell script boiler plate, and helper functions.
 # Written by Gary V. Vaughan, 2004
@@ -1257,6 +1257,57 @@ func_relative_path ()
 }

+# func_quote ARG
+# --------------
+# Aesthetically quote one ARG, store the result into $func_quote_result.  Note
+# that we keep attention to performance here (so far O(N) complexity as long as
+# func_append is O(1)).
+func_quote ()
+{
+    $debug_cmd
+
+    func_quote_result=$1
+
+    case $func_quote_result in
+      *[\\\`\"\$]*)
+        case $func_quote_result in
+          *'*'*|*'['*)
+            func_quote_result=`$ECHO "$func_quote_result" | $SED "$sed_quote_subst"`
+            return 0
+            ;;
+        esac
+
+        func_quote_old_IFS=$IFS
+        for _G_char in '\' '`' '"' '$'
+        do
+          # STATE($1) PREV($2) SEPARATOR($3)
+          set start "" ""
+          func_quote_result=dummy"$_G_char$func_quote_result$_G_char"dummy
+          IFS=$_G_char
+          for _G_part in $func_quote_result
+          do
+            case $1 in
+            quote)
+              func_append func_quote_result "$3$2"
+              set quote "$_G_part" "\\$_G_char"
+              ;;
+            start)
+              set first "" ""
+              func_quote_result=
+              ;;
+            first)
+              set quote "$_G_part" ""
+              ;;
+            esac
+          done
+          IFS=$func_quote_old_IFS
+        done
+        ;;
+      *) ;;
+    esac
+}
+
+
 # func_quote_for_eval ARG...
 # --------------------------
 # Aesthetically quote ARGs to be evaled later.
@@ -1275,7 +1326,8 @@ func_quote_for_eval ()
     while test 0 -lt $#; do
       case $1 in
         *[\\\`\"\$]*)
-	  _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;;
+          func_quote "$1"
+          _G_unquoted_arg=$func_quote_result ;;
         *)
           _G_unquoted_arg=$1 ;;
       esac
diff --git a/build-aux/ltmain.in b/build-aux/ltmain.in
index 0c40da0..24acefd 100644
--- a/build-aux/ltmain.in
+++ b/build-aux/ltmain.in
@@ -3346,7 +3346,8 @@ else
   if test \"\$libtool_execute_magic\" != \"$magic\"; then
     file=\"\$0\""
 
-    qECHO=`$ECHO "$ECHO" | $SED "$sed_quote_subst"`
+    func_quote "$ECHO"
+    qECHO=$func_quote_result
     $ECHO "\
 
 # A function that is used when there is no print builtin or printf.
@@ -8596,8 +8597,8 @@ EOF
 	    relink_command="$var=$func_quote_for_eval_result; export $var; $relink_command"
 	  fi
 	done
-	relink_command="(cd `pwd`; $relink_command)"
-	relink_command=`$ECHO "$relink_command" | $SED "$sed_quote_subst"`
+	func_quote "(cd `pwd`; $relink_command)"
+	relink_command=$func_quote_result
       fi
 
       # Only actually do things if not in dry run mode.
@@ -8843,7 +8844,8 @@ EOF
       done
       # Quote the link command for shipping.
       relink_command="(cd `pwd`; $SHELL \"$progpath\" $preserve_args --mode=relink $libtool_args @inst_prefix_dir@)"
-      relink_command=`$ECHO "$relink_command" | $SED "$sed_quote_subst"`
+      func_quote "$relink_command"
+      relink_command=$func_quote_result
       if test yes = "$hardcode_automatic"; then
 	relink_command=
       fi
diff --git a/gl/build-aux/funclib.sh b/gl/build-aux/funclib.sh
index 39d972e..8032e6b 100644
--- a/gl/build-aux/funclib.sh
+++ b/gl/build-aux/funclib.sh
@@ -1,5 +1,5 @@
 # Set a version string for this script.
-scriptversion=2015-01-20.17; # UTC
+scriptversion=2015-10-04.22; # UTC
 
 # General shell script boiler plate, and helper functions.
 # Written by Gary V. Vaughan, 2004
@@ -1026,6 +1026,57 @@ func_relative_path ()
 }

+# func_quote ARG
+# --------------
+# Aesthetically quote one ARG, store the result into $func_quote_result.  Note
+# that we keep attention to performance here (so far O(N) complexity as long as
+# func_append is O(1)).
+func_quote ()
+{
+    $debug_cmd
+
+    func_quote_result=$1
+
+    case $func_quote_result in
+      *[\\\`\"\$]*)
+        case $func_quote_result in
+          *'*'*|*'['*)
+            func_quote_result=`$ECHO "$func_quote_result" | $SED "$sed_quote_subst"`
+            return 0
+            ;;
+        esac
+
+        func_quote_old_IFS=$IFS
+        for _G_char in '\' '`' '"' '$'
+        do
+          # STATE($1) PREV($2) SEPARATOR($3)
+          set start "" ""
+          func_quote_result=dummy"$_G_char$func_quote_result$_G_char"dummy
+          IFS=$_G_char
+          for _G_part in $func_quote_result
+          do
+            case $1 in
+            quote)
+              func_append func_quote_result "$3$2"
+              set quote "$_G_part" "\\$_G_char"
+              ;;
+            start)
+              set first "" ""
+              func_quote_result=
+              ;;
+            first)
+              set quote "$_G_part" ""
+              ;;
+            esac
+          done
+          IFS=$func_quote_old_IFS
+        done
+        ;;
+      *) ;;
+    esac
+}
+
+
 # func_quote_for_eval ARG...
 # --------------------------
 # Aesthetically quote ARGs to be evaled later.
@@ -1044,7 +1095,8 @@ func_quote_for_eval ()
     while test 0 -lt $#; do
       case $1 in
         *[\\\`\"\$]*)
-	  _G_unquoted_arg=`printf '%s\n' "$1" |$SED "$sed_quote_subst"` ;;
+          func_quote "$1"
+          _G_unquoted_arg=$func_quote_result ;;
         *)
           _G_unquoted_arg=$1 ;;
       esac
-- 
2.5.0

>From 97d39fb30958e86e1fe4d5fc8c953c66183cba20 Mon Sep 17 00:00:00 2001
From: Pavel Raiskup <[email-masked]>
Date: Mon, 5 Oct 2015 13:16:08 +0200
Subject: [PATCH 2/2] libtool: optimizing options-parser hooks

Its not necessary to (re)func_quote_for_eval in each function in
the hook hierarchy.  Usually is enough if the leaf function
does func_quote_for_eval and its caller just re-uses the
<CALLEE>_return variable.

This is follow up for the previous commit.

* gl/build-aux/options-parser (func_run_hooks): Propagate
$EXIT_SUCCESS return code down to caller if *any* hook succeeded.
Never re-quote the result -- either the arguments are left
untouched, or the options have already been properly quoted by
succeeding hooks.
(func_parse_options): Quote '$@' and return $EXIT_SUCCESS only if
we changed something.
(func_validate_options): Likewise.
(func_options_prep): Likewise.
(func_options_finish): New hook-caller for 'func_options' hooks.
(func_options): Propagate return value down to top-level caller,
but pay attention we have always set $func_options_result.
* build-aux/ltmain.in (libtool_options_prep): Quote '$@' and
return $EXIT_SUCCESS only if we changed something.
(libtool_parse_options): Likewise.
* bootstrap: Sync gl/build-aux/with option-parser.
---
 bootstrap                   | 171 +++++++++++++++++++++++++++++++-------------
 build-aux/ltmain.in         |  35 ++++++---
 gl/build-aux/options-parser | 171 +++++++++++++++++++++++++++++++-------------
 3 files changed, 271 insertions(+), 106 deletions(-)

diff --git a/bootstrap b/bootstrap
index 2649478..f9aac68 100755
--- a/bootstrap
+++ b/bootstrap
@@ -1588,7 +1588,7 @@ func_lt_ver ()
 #! /bin/sh
 
 # Set a version string for this script.
-scriptversion=2014-01-07.03; # UTC
+scriptversion=2015-10-07.11; # UTC
 
 # A portable, pluggable option parser for Bourne shell.
 # Written by Gary V. Vaughan, 2010
@@ -1748,6 +1748,8 @@ func_run_hooks ()
 {
     $debug_cmd
 
+    _G_rc_run_hooks=false
+
     case " $hookable_fns " in
       *" $1 "*) ;;
       *) func_fatal_error "'$1' does not support hook funcions.n" ;;
@@ -1756,16 +1758,16 @@ func_run_hooks ()
     eval _G_hook_fns=\$$1_hooks; shift
 
     for _G_hook in $_G_hook_fns; do
-      eval $_G_hook '"$@"'
-
-      # store returned options list back into positional
-      # parameters for next 'cmd' execution.
-      eval _G_hook_result=\$${_G_hook}_result
-      eval set dummy "$_G_hook_result"; shift
+      if eval $_G_hook '"$@"'; then
+        # store returned options list back into positional
+        # parameters for next 'cmd' execution.
+        eval _G_hook_result=\$${_G_hook}_result
+        eval set dummy "$_G_hook_result"; shift
+        _G_rc_run_hooks=:
+      fi
     done
 
-    func_quote_for_eval ${1+"$@"}
-    func_run_hooks_result=$func_quote_for_eval_result
+    $_G_rc_run_hooks && func_run_hooks_result=$_G_hook_result
 }

@@ -1775,10 +1777,16 @@ func_run_hooks ()
 ## --------------- ##
 
 # In order to add your own option parsing hooks, you must accept the
-# full positional parameter list in your hook function, remove any
-# options that you action, and then pass back the remaining unprocessed
+# full positional parameter list in your hook function, you may remove/edit
+# any options that you action, and then pass back the remaining unprocessed
 # options in '<hooked_function_name>_result', escaped suitably for
-# 'eval'.  Like this:
+# 'eval'.  In this case you also must return $EXIT_SUCCESS to let the
+# hook's caller know that it should pay attention to
+# '<hooked_function_name>_result'.  Returning $EXIT_FAILURE signalizes that
+# arguments are left untouched by the hook and therefore caller will ignore the
+# result variable.
+#
+# Like this:
 #
 #    my_options_prep ()
 #    {
@@ -1788,9 +1796,11 @@ func_run_hooks ()
 #        usage_message=$usage_message'
 #      -s, --silent       don'\''t print informational messages
 #    '
-#
-#        func_quote_for_eval ${1+"$@"}
-#        my_options_prep_result=$func_quote_for_eval_result
+#        # No change in '$@' (ignored completely by this hook).  There is
+#        # no need to do the equivalent (but slower) action:
+#        # func_quote_for_eval ${1+"$@"}
+#        # my_options_prep_result=$func_quote_for_eval_result
+#        false
 #    }
 #    func_add_hook func_options_prep my_options_prep
 #
@@ -1799,25 +1809,37 @@ func_run_hooks ()
 #    {
 #        $debug_cmd
 #
+#        args_changed=false
+#
 #        # Note that for efficiency, we parse as many options as we can
 #        # recognise in a loop before passing the remainder back to the
 #        # caller on the first unrecognised argument we encounter.
 #        while test $# -gt 0; do
 #          opt=$1; shift
 #          case $opt in
-#            --silent|-s) opt_silent=: ;;
+#            --silent|-s) opt_silent=:
+#                         args_changed=:
+#                         ;;
 #            # Separate non-argument short options:
 #            -s*)         func_split_short_opt "$_G_opt"
 #                         set dummy "$func_split_short_opt_name" \
 #                             "-$func_split_short_opt_arg" ${1+"$@"}
 #                         shift
+#                         args_changed=:
 #                         ;;
-#            *)            set dummy "$_G_opt" "$*"; shift; break ;;
+#            *)           # Make sure the first unrecognised option "$_G_opt"
+#                         # is added back to "$@", we could need that later
+#                         # if $args_changed is true.
+#                         set dummy "$_G_opt" ${1+"$@"}; shift; break ;;
 #          esac
 #        done
 #
-#        func_quote_for_eval ${1+"$@"}
-#        my_silent_option_result=$func_quote_for_eval_result
+#        if $args_changed; then
+#          func_quote_for_eval ${1+"$@"}
+#          my_silent_option_result=$func_quote_for_eval_result
+#        fi
+#
+#        $args_changed
 #    }
 #    func_add_hook func_parse_options my_silent_option
 #
@@ -1829,16 +1851,32 @@ func_run_hooks ()
 #        $opt_silent && $opt_verbose && func_fatal_help "\
 #    '--silent' and '--verbose' options are mutually exclusive."
 #
-#        func_quote_for_eval ${1+"$@"}
-#        my_option_validation_result=$func_quote_for_eval_result
+#        false
 #    }
 #    func_add_hook func_validate_options my_option_validation
 #
-# You'll alse need to manually amend $usage_message to reflect the extra
+# You'll also need to manually amend $usage_message to reflect the extra
 # options you parse.  It's preferable to append if you can, so that
 # multiple option parsing hooks can be added safely.

+# func_options_finish [ARG]...
+# ----------------------------
+# Finishing the option parse loop (call 'func_options' hooks ATM).
+func_options_finish ()
+{
+    $debug_cmd
+
+    _G_func_options_finish_exit=false
+    if func_run_hooks func_options ${1+"$@"}; then
+      func_options_finish_result=$func_run_hooks_result
+      _G_func_options_finish_exit=:
+    fi
+
+    $_G_func_options_finish_exit
+}
+
+
 # func_options [ARG]...
 # ---------------------
 # All the functions called inside func_options are hookable. See the
@@ -1848,17 +1886,28 @@ func_options ()
 {
     $debug_cmd
 
-    func_options_prep ${1+"$@"}
-    eval func_parse_options \
-        ${func_options_prep_result+"$func_options_prep_result"}
-    eval func_validate_options \
-        ${func_parse_options_result+"$func_parse_options_result"}
+    _G_rc_options=false
 
-    eval func_run_hooks func_options \
-        ${func_validate_options_result+"$func_validate_options_result"}
+    for my_func in options_prep parse_options validate_options options_finish
+    do
+      if eval func_$my_func '${1+"$@"}'; then
+        eval _G_res_var='$'"func_${my_func}_result"
+        eval set dummy "$_G_res_var" ; shift
+        _G_rc_options=:
+      fi
+    done
 
-    # save modified positional parameters for caller
-    func_options_result=$func_run_hooks_result
+    # Save modified positional parameters for caller.  As a top-level
+    # options-parser function we always need to set the 'func_options_result'
+    # variable (regardless the $_G_rc_options value).
+    if $_G_rc_options; then
+      func_options_result=$_G_res_var
+    else
+      func_quote_for_eval ${1+"$@"}
+      func_options_result=$func_quote_for_eval_result
+    fi
+
+    $_G_rc_options
 }

@@ -1867,9 +1916,9 @@ func_options ()
 # All initialisations required before starting the option parse loop.
 # Note that when calling hook functions, we pass through the list of
 # positional parameters.  If a hook function modifies that list, and
-# needs to propogate that back to rest of this script, then the complete
+# needs to propagate that back to rest of this script, then the complete
 # modified list must be put in 'func_run_hooks_result' before
-# returning.
+# returning $EXIT_SUCCESS (otherwise $EXIT_FAILURE is returned).
 func_hookable func_options_prep
 func_options_prep ()
 {
@@ -1879,10 +1928,14 @@ func_options_prep ()
     opt_verbose=false
     opt_warning_types=
 
-    func_run_hooks func_options_prep ${1+"$@"}
+    _G_rc_options_prep=false
+    if func_run_hooks func_options_prep ${1+"$@"}; then
+      _G_rc_options_prep=:
+      # save modified positional parameters for caller
+      func_options_prep_result=$func_run_hooks_result
+    fi
 
-    # save modified positional parameters for caller
-    func_options_prep_result=$func_run_hooks_result
+    $_G_rc_options_prep
 }

@@ -1896,18 +1949,20 @@ func_parse_options ()
 
     func_parse_options_result=
 
+    _G_rc_parse_options=false
     # this just eases exit handling
     while test $# -gt 0; do
       # Defer to hook functions for initial option parsing, so they
       # get priority in the event of reusing an option name.
-      func_run_hooks func_parse_options ${1+"$@"}
-
-      # Adjust func_parse_options positional parameters to match
-      eval set dummy "$func_run_hooks_result"; shift
+      if func_run_hooks func_parse_options ${1+"$@"}; then
+        eval set dummy "$func_run_hooks_result"; shift
+        _G_rc_parse_options=:
+      fi
 
       # Break out of the loop if we already parsed every option.
       test $# -gt 0 || break
 
+      _G_match_parse_options=:
       _G_opt=$1
       shift
       case $_G_opt in
@@ -1922,7 +1977,10 @@ func_parse_options ()
 		      ;;
 
         --warnings|--warning|-W)
-                      test $# = 0 && func_missing_arg $_G_opt && break
+                      if test $# = 0 && func_missing_arg $_G_opt; then
+                        _G_rc_parse_options=:
+                        break
+                      fi
                       case " $warning_categories $1" in
                         *" $1 "*)
                           # trailing space prevents matching last $1 above
@@ -1975,15 +2033,25 @@ func_parse_options ()
                       shift
                       ;;
 
-        --)           break ;;
+        --)           _G_rc_parse_options=: ; break ;;
         -*)           func_fatal_help "unrecognised option: '$_G_opt'" ;;
-        *)            set dummy "$_G_opt" ${1+"$@"}; shift; break ;;
+        *)            set dummy "$_G_opt" ${1+"$@"}; shift
+                      _G_match_parse_options=false
+                      break
+                      ;;
       esac
+
+      $_G_match_parse_options && _G_rc_parse_options=:
     done
 
-    # save modified positional parameters for caller
-    func_quote_for_eval ${1+"$@"}
-    func_parse_options_result=$func_quote_for_eval_result
+
+    if $_G_rc_parse_options; then
+      # save modified positional parameters for caller
+      func_quote_for_eval ${1+"$@"}
+      func_parse_options_result=$func_quote_for_eval_result
+    fi
+
+    $_G_rc_parse_options
 }

@@ -1996,16 +2064,21 @@ func_validate_options ()
 {
     $debug_cmd
 
+    _G_rc_validate_options=false
+
     # Display all warnings if -W was not given.
     test -n "$opt_warning_types" || opt_warning_types=" $warning_categories"
 
-    func_run_hooks func_validate_options ${1+"$@"}
+    if func_run_hooks func_validate_options ${1+"$@"}; then
+      # save modified positional parameters for caller
+      func_validate_options_result=$func_run_hooks_result
+      _G_rc_validate_options=:
+    fi
 
     # Bail if the options were screwed!
     $exit_cmd $EXIT_FAILURE
 
-    # save modified positional parameters for caller
-    func_validate_options_result=$func_run_hooks_result
+    $_G_rc_validate_options
 }

diff --git a/build-aux/ltmain.in b/build-aux/ltmain.in
index 24acefd..b4c6bcd 100644
--- a/build-aux/ltmain.in
+++ b/build-aux/ltmain.in
@@ -358,6 +358,8 @@ libtool_options_prep ()
     nonopt=
     preserve_args=
 
+    _G_rc_lt_options_prep=:
+
     # Shorthand for --mode=foo, only valid as the first argument
     case $1 in
     clean|clea|cle|cl)
@@ -381,11 +383,18 @@ libtool_options_prep ()
     uninstall|uninstal|uninsta|uninst|unins|unin|uni|un|u)
       shift; set dummy --mode uninstall ${1+"$@"}; shift
       ;;
+    *)
+      _G_rc_lt_options_prep=false
+      ;;
     esac
 
-    # Pass back the list of options.
-    func_quote_for_eval ${1+"$@"}
-    libtool_options_prep_result=$func_quote_for_eval_result
+    if $_G_rc_lt_options_prep; then
+      # Pass back the list of options.
+      func_quote_for_eval ${1+"$@"}
+      libtool_options_prep_result=$func_quote_for_eval_result
+    fi
+
+    $_G_rc_lt_options_prep
 }
 func_add_hook func_options_prep libtool_options_prep
 
@@ -397,9 +406,12 @@ libtool_parse_options ()
 {
     $debug_cmd
 
+    _G_rc_lt_parse_options=false
+
     # Perform our own loop to consume as many options as possible in
     # each iteration.
     while test $# -gt 0; do
+      _G_match_lt_parse_options=:
       _G_opt=$1
       shift
       case $_G_opt in
@@ -474,15 +486,22 @@ libtool_parse_options ()
                         func_append preserve_args " $_G_opt"
                         ;;
 
-	# An option not handled by this hook function:
-        *)		set dummy "$_G_opt" ${1+"$@"};	shift; break  ;;
+        # An option not handled by this hook function:
+        *)              set dummy "$_G_opt" ${1+"$@"} ; shift
+                        _G_match_lt_parse_options=false
+                        break
+                        ;;
       esac
+      $_G_match_lt_parse_options && _G_rc_lt_parse_options=:
     done
 
+    if $_G_rc_lt_parse_options; then
+      # save modified positional parameters for caller
+      func_quote_for_eval ${1+"$@"}
+      libtool_parse_options_result=$func_quote_for_eval_result
+    fi
 
-    # save modified positional parameters for caller
-    func_quote_for_eval ${1+"$@"}
-    libtool_parse_options_result=$func_quote_for_eval_result
+    $_G_rc_lt_parse_options
 }
 func_add_hook func_parse_options libtool_parse_options
 
diff --git a/gl/build-aux/options-parser b/gl/build-aux/options-parser
index d651f1d..4c7e9cb 100644
--- a/gl/build-aux/options-parser
+++ b/gl/build-aux/options-parser
@@ -1,7 +1,7 @@
 #! /bin/sh
 
 # Set a version string for this script.
-scriptversion=2014-01-07.03; # UTC
+scriptversion=2015-10-07.11; # UTC
 
 # A portable, pluggable option parser for Bourne shell.
 # Written by Gary V. Vaughan, 2010
@@ -161,6 +161,8 @@ func_run_hooks ()
 {
     $debug_cmd
 
+    _G_rc_run_hooks=false
+
     case " $hookable_fns " in
       *" $1 "*) ;;
       *) func_fatal_error "'$1' does not support hook funcions.n" ;;
@@ -169,16 +171,16 @@ func_run_hooks ()
     eval _G_hook_fns=\$$1_hooks; shift
 
     for _G_hook in $_G_hook_fns; do
-      eval $_G_hook '"$@"'
-
-      # store returned options list back into positional
-      # parameters for next 'cmd' execution.
-      eval _G_hook_result=\$${_G_hook}_result
-      eval set dummy "$_G_hook_result"; shift
+      if eval $_G_hook '"$@"'; then
+        # store returned options list back into positional
+        # parameters for next 'cmd' execution.
+        eval _G_hook_result=\$${_G_hook}_result
+        eval set dummy "$_G_hook_result"; shift
+        _G_rc_run_hooks=:
+      fi
     done
 
-    func_quote_for_eval ${1+"$@"}
-    func_run_hooks_result=$func_quote_for_eval_result
+    $_G_rc_run_hooks && func_run_hooks_result=$_G_hook_result
 }

@@ -188,10 +190,16 @@ func_run_hooks ()
 ## --------------- ##
 
 # In order to add your own option parsing hooks, you must accept the
-# full positional parameter list in your hook function, remove any
-# options that you action, and then pass back the remaining unprocessed
+# full positional parameter list in your hook function, you may remove/edit
+# any options that you action, and then pass back the remaining unprocessed
 # options in '<hooked_function_name>_result', escaped suitably for
-# 'eval'.  Like this:
+# 'eval'.  In this case you also must return $EXIT_SUCCESS to let the
+# hook's caller know that it should pay attention to
+# '<hooked_function_name>_result'.  Returning $EXIT_FAILURE signalizes that
+# arguments are left untouched by the hook and therefore caller will ignore the
+# result variable.
+#
+# Like this:
 #
 #    my_options_prep ()
 #    {
@@ -201,9 +209,11 @@ func_run_hooks ()
 #        usage_message=$usage_message'
 #      -s, --silent       don'\''t print informational messages
 #    '
-#
-#        func_quote_for_eval ${1+"$@"}
-#        my_options_prep_result=$func_quote_for_eval_result
+#        # No change in '$@' (ignored completely by this hook).  There is
+#        # no need to do the equivalent (but slower) action:
+#        # func_quote_for_eval ${1+"$@"}
+#        # my_options_prep_result=$func_quote_for_eval_result
+#        false
 #    }
 #    func_add_hook func_options_prep my_options_prep
 #
@@ -212,25 +222,37 @@ func_run_hooks ()
 #    {
 #        $debug_cmd
 #
+#        args_changed=false
+#
 #        # Note that for efficiency, we parse as many options as we can
 #        # recognise in a loop before passing the remainder back to the
 #        # caller on the first unrecognised argument we encounter.
 #        while test $# -gt 0; do
 #          opt=$1; shift
 #          case $opt in
-#            --silent|-s) opt_silent=: ;;
+#            --silent|-s) opt_silent=:
+#                         args_changed=:
+#                         ;;
 #            # Separate non-argument short options:
 #            -s*)         func_split_short_opt "$_G_opt"
 #                         set dummy "$func_split_short_opt_name" \
 #                             "-$func_split_short_opt_arg" ${1+"$@"}
 #                         shift
+#                         args_changed=:
 #                         ;;
-#            *)            set dummy "$_G_opt" "$*"; shift; break ;;
+#            *)           # Make sure the first unrecognised option "$_G_opt"
+#                         # is added back to "$@", we could need that later
+#                         # if $args_changed is true.
+#                         set dummy "$_G_opt" ${1+"$@"}; shift; break ;;
 #          esac
 #        done
 #
-#        func_quote_for_eval ${1+"$@"}
-#        my_silent_option_result=$func_quote_for_eval_result
+#        if $args_changed; then
+#          func_quote_for_eval ${1+"$@"}
+#          my_silent_option_result=$func_quote_for_eval_result
+#        fi
+#
+#        $args_changed
 #    }
 #    func_add_hook func_parse_options my_silent_option
 #
@@ -242,16 +264,32 @@ func_run_hooks ()
 #        $opt_silent && $opt_verbose && func_fatal_help "\
 #    '--silent' and '--verbose' options are mutually exclusive."
 #
-#        func_quote_for_eval ${1+"$@"}
-#        my_option_validation_result=$func_quote_for_eval_result
+#        false
 #    }
 #    func_add_hook func_validate_options my_option_validation
 #
-# You'll alse need to manually amend $usage_message to reflect the extra
+# You'll also need to manually amend $usage_message to reflect the extra
 # options you parse.  It's preferable to append if you can, so that
 # multiple option parsing hooks can be added safely.

+# func_options_finish [ARG]...
+# ----------------------------
+# Finishing the option parse loop (call 'func_options' hooks ATM).
+func_options_finish ()
+{
+    $debug_cmd
+
+    _G_func_options_finish_exit=false
+    if func_run_hooks func_options ${1+"$@"}; then
+      func_options_finish_result=$func_run_hooks_result
+      _G_func_options_finish_exit=:
+    fi
+
+    $_G_func_options_finish_exit
+}
+
+
 # func_options [ARG]...
 # ---------------------
 # All the functions called inside func_options are hookable. See the
@@ -261,17 +299,28 @@ func_options ()
 {
     $debug_cmd
 
-    func_options_prep ${1+"$@"}
-    eval func_parse_options \
-        ${func_options_prep_result+"$func_options_prep_result"}
-    eval func_validate_options \
-        ${func_parse_options_result+"$func_parse_options_result"}
+    _G_rc_options=false
 
-    eval func_run_hooks func_options \
-        ${func_validate_options_result+"$func_validate_options_result"}
+    for my_func in options_prep parse_options validate_options options_finish
+    do
+      if eval func_$my_func '${1+"$@"}'; then
+        eval _G_res_var='$'"func_${my_func}_result"
+        eval set dummy "$_G_res_var" ; shift
+        _G_rc_options=:
+      fi
+    done
 
-    # save modified positional parameters for caller
-    func_options_result=$func_run_hooks_result
+    # Save modified positional parameters for caller.  As a top-level
+    # options-parser function we always need to set the 'func_options_result'
+    # variable (regardless the $_G_rc_options value).
+    if $_G_rc_options; then
+      func_options_result=$_G_res_var
+    else
+      func_quote_for_eval ${1+"$@"}
+      func_options_result=$func_quote_for_eval_result
+    fi
+
+    $_G_rc_options
 }

@@ -280,9 +329,9 @@ func_options ()
 # All initialisations required before starting the option parse loop.
 # Note that when calling hook functions, we pass through the list of
 # positional parameters.  If a hook function modifies that list, and
-# needs to propogate that back to rest of this script, then the complete
+# needs to propagate that back to rest of this script, then the complete
 # modified list must be put in 'func_run_hooks_result' before
-# returning.
+# returning $EXIT_SUCCESS (otherwise $EXIT_FAILURE is returned).
 func_hookable func_options_prep
 func_options_prep ()
 {
@@ -292,10 +341,14 @@ func_options_prep ()
     opt_verbose=false
     opt_warning_types=
 
-    func_run_hooks func_options_prep ${1+"$@"}
+    _G_rc_options_prep=false
+    if func_run_hooks func_options_prep ${1+"$@"}; then
+      _G_rc_options_prep=:
+      # save modified positional parameters for caller
+      func_options_prep_result=$func_run_hooks_result
+    fi
 
-    # save modified positional parameters for caller
-    func_options_prep_result=$func_run_hooks_result
+    $_G_rc_options_prep
 }

@@ -309,18 +362,20 @@ func_parse_options ()
 
     func_parse_options_result=
 
+    _G_rc_parse_options=false
     # this just eases exit handling
     while test $# -gt 0; do
       # Defer to hook functions for initial option parsing, so they
       # get priority in the event of reusing an option name.
-      func_run_hooks func_parse_options ${1+"$@"}
-
-      # Adjust func_parse_options positional parameters to match
-      eval set dummy "$func_run_hooks_result"; shift
+      if func_run_hooks func_parse_options ${1+"$@"}; then
+        eval set dummy "$func_run_hooks_result"; shift
+        _G_rc_parse_options=:
+      fi
 
       # Break out of the loop if we already parsed every option.
       test $# -gt 0 || break
 
+      _G_match_parse_options=:
       _G_opt=$1
       shift
       case $_G_opt in
@@ -335,7 +390,10 @@ func_parse_options ()
 		      ;;
 
         --warnings|--warning|-W)
-                      test $# = 0 && func_missing_arg $_G_opt && break
+                      if test $# = 0 && func_missing_arg $_G_opt; then
+                        _G_rc_parse_options=:
+                        break
+                      fi
                       case " $warning_categories $1" in
                         *" $1 "*)
                           # trailing space prevents matching last $1 above
@@ -388,15 +446,25 @@ func_parse_options ()
                       shift
                       ;;
 
-        --)           break ;;
+        --)           _G_rc_parse_options=: ; break ;;
         -*)           func_fatal_help "unrecognised option: '$_G_opt'" ;;
-        *)            set dummy "$_G_opt" ${1+"$@"}; shift; break ;;
+        *)            set dummy "$_G_opt" ${1+"$@"}; shift
+                      _G_match_parse_options=false
+                      break
+                      ;;
       esac
+
+      $_G_match_parse_options && _G_rc_parse_options=:
     done
 
-    # save modified positional parameters for caller
-    func_quote_for_eval ${1+"$@"}
-    func_parse_options_result=$func_quote_for_eval_result
+
+    if $_G_rc_parse_options; then
+      # save modified positional parameters for caller
+      func_quote_for_eval ${1+"$@"}
+      func_parse_options_result=$func_quote_for_eval_result
+    fi
+
+    $_G_rc_parse_options
 }

@@ -409,16 +477,21 @@ func_validate_options ()
 {
     $debug_cmd
 
+    _G_rc_validate_options=false
+
     # Display all warnings if -W was not given.
     test -n "$opt_warning_types" || opt_warning_types=" $warning_categories"
 
-    func_run_hooks func_validate_options ${1+"$@"}
+    if func_run_hooks func_validate_options ${1+"$@"}; then
+      # save modified positional parameters for caller
+      func_validate_options_result=$func_run_hooks_result
+      _G_rc_validate_options=:
+    fi
 
     # Bail if the options were screwed!
     $exit_cmd $EXIT_FAILURE
 
-    # save modified positional parameters for caller
-    func_validate_options_result=$func_run_hooks_result
+    $_G_rc_validate_options
 }

-- 
2.5.0