#! /bin/sh

# Extract macro arguments from autotools input with GNU M4.
# Written by Gary V. Vaughan, 2010
#
# This is free software.  There is NO warranty; not even for
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#
# Copyright (C) 2010-2019, 2021 Bootstrap Authors
#
# This file is dual licensed under the terms of the MIT license
# <https://opensource.org/license/MIT>, and GPL version 2 or later
# <http://www.gnu.org/licenses/gpl-2.0.html>.  You must apply one of
# these licenses when using or redistributing this software or any of
# the files within it.  See the URLs above, or the file `LICENSE`
# included in the Bootstrap distribution for the full license texts.

# Please report bugs or propose patches to:
# <https://github.com/gnulib-modules/bootstrap/issues>

# Make sure we've evaluated scripts we depend on.
test -z "$progpath" && . `echo "$0" |${SED-sed} 's|[^/]*$||'`/funclib.sh
test extract-trace = "$progname" && . `echo "$0" |${SED-sed} 's|[^/]*$||'`/options-parser

# Set a version string.
scriptversion=2019-02-19.15; # UTC


## ------ ##
## Usage. ##
## ------ ##

# Run './extract-trace --help' for help with using this script from the
# command line.
#
# Or source first 'options-parser' and then this file into your own
# scripts in order to make use of the function and variable framework
# they define, and also to avoid the overhead of forking to run this
# script in its own process on every call.



## ----------------- ##
## Helper functions. ##
## ----------------- ##

# This section contains the helper functions used by the rest of
# 'extract-trace'.


# func_autoconf_configure MAYBE-CONFIGURE-FILE
# --------------------------------------------
# Ensure that MAYBE-CONFIGURE-FILE is the name of a file in the current
# directory that contains an uncommented call to AC_INIT.
func_autoconf_configure ()
{
    $debug_cmd

    _G_sed_no_comment='
      s|#.*$||
      s|^dnl .*$||
      s| dnl .*$||'
    _G_ac_init=

    # If we were passed a genuine file, make sure it calls AC_INIT.
    test -f "$1" \
      && _G_ac_init=`$SED "$_G_sed_no_comment" "$1" |$GREP AC_INIT`

    # Otherwise it is not a genuine Autoconf input file.
    test -n "$_G_ac_init"
    _G_status=$?

    test 0 -ne "$_G_status" \
      && func_verbose "'$1' not using Autoconf"

    (exit $_G_status)
}


# func_tool_version_output CMD [FATAL-ERROR-MSG]
# ----------------------------------------------
# Attempt to run 'CMD --version', discarding errors.  The output can be
# ignored by redirecting stdout, and this function used simply to test
# whether the command exists and exits normally when passed a
# '--version' argument.
# When FATAL-ERROR-MSG is given, then this function will display the
# message and exit if running 'CMD --version' returns a non-zero exit
# status.
func_tool_version_output ()
{
    $debug_cmd

    _G_cmd=$1
    _G_fatal_error_msg=$2

    # Some tools, like 'git2cl' produce thousands of lines of output
    # unless stdin is /dev/null - in that case we want to return
    # successfully without saving all of that output.  Other tools,
    # such as 'help2man' exit with a non-zero status when stdin comes
    # from /dev/null, so we re-execute without /dev/null if that
    # happens.  This means that occasionally, the output from both calls
    # ends up in the result, but the alternative would be to discard the
    # output from one call, and hope the other produces something useful.
    { $_G_cmd --version </dev/null || $_G_cmd --version; } 2>/dev/null
    _G_status=$?

    test 0 -ne "$_G_status" && test -n "$_G_fatal_error_msg" \
        && func_fatal_error "$_G_fatal_error_msg"

    (exit $_G_status)
}


# func_tool_version_number CMD [FATAL-ERROR-MSG]
# ----------------------------------------------
# Pass arguments to func_tool_version_output, but set
# $func_tool_version_number_result to the last dot delimited digit string
# on the first line of output.
func_tool_version_number ()
{
    $debug_cmd

    _G_verout=`func_tool_version_output "$@"`
    _G_status=$?

    # A version number starts with a digit following a space on the first
    # line of output from `--version`.
    _G_verout=`echo "$_G_verout" |sed 1q`
    if test -n "$_G_verout"; then
      _G_vernum=`expr "$_G_verout" : '.* \([0-9][^ ]*\)'`
    fi

    if test -n "$_G_vernum"; then
      printf '%s\n' "$_G_vernum"
    else
      printf '%s\n' "$_G_verout"
    fi

    (exit $_G_status)
}


# func_find_tool ENVVAR NAMES...
# ------------------------------
# Search for a required program.  Use the value of ENVVAR, if set,
# otherwise find the first of the NAMES that can be run (i.e.,
# supports --version).  If found, set ENVVAR to the program name,
# die otherwise.
func_find_tool ()
{
    $debug_cmd

    _G_find_tool_envvar=$1
    shift
    _G_find_tool_names=$@
    eval "_G_find_tool_res=\$$_G_find_tool_envvar"
    if test -n "$_G_find_tool_res"; then
      _G_find_tool_error_prefix="\$$find_tool_envvar: "
    else
      _G_find_tool_res=
      _G_bestver=
      for _G_prog
      do
        _G_find_tool_save_IFS=$IFS
        IFS=${PATH_SEPARATOR-:}
	for _G_dir in $PATH; do
	  IFS=$_G_find_tool_save_IFS
	  _G_progpath=$_G_dir/$_G_prog
          test -r "$_G_progpath" && {
            _G_curver=`func_tool_version_number $_G_progpath`
	    case $_G_bestver,$_G_curver in
	    ,)
	      # first non--version responsive prog sticks!
              test -n "$_G_progpath" || _G_find_tool_res=$_G_progpath
              ;;
            ,*)
	      # first --version responsive prog beats non--version responsive!
	      _G_find_tool_res=$_G_progpath
	      _G_bestver=$_G_curver
	      ;;
	    *,*)
	      # another --version responsive prog must be newer to beat previous one!
	      test "x$_G_curver" = "x$_G_bestver" \
		|| func_lt_ver "$_G_curver" "$_G_bestver" \
		|| {
		     _G_find_tool_res=$_G_progpath
		     _G_bestver=$_G_curver
	           }
	      ;;
	    esac
          }
	done
	IFS=$_G_find_tool_save_IFS
      done
    fi
    if test -n "$_G_find_tool_res"; then
      func_tool_version_number >/dev/null $_G_find_tool_res "\
${_G_find_tool_error_prefix}Cannot run '$_G_find_tool_res --version'"

      # Make sure the result is exported to the environment for children
      # to use.
      eval "$_G_find_tool_envvar=\$_G_find_tool_res"
      eval "export $_G_find_tool_envvar"
    else
      func_error "\
One of these is required:
       $_G_find_tool_names"
    fi
}



## -------------------- ##
## Resource management. ##
## -------------------- ##

# This section contains definitions for functions that each ensure a
# particular resource (a file, or a non-empty configuration variable for
# example) is available, and if appropriate to extract default values
# from pertinent package files.  Where a variable already has a non-
# empty value (as set by the package's 'bootstrap.conf'), that value is
# used in preference to deriving the default. Call them using their
# associated 'require_*' variable to ensure that they are executed, at
# most, once.
#
# It's entirely deliberate that calling these functions can set
# variables that don't obey the namespace limitations obeyed by the rest
# of this file, in order that that they be as useful as possible to
# callers.


# require_configure_ac
# --------------------
# Ensure that there is a 'configure.ac' or 'configure.in' file in the
# current directory that contains an uncommented call to AC_INIT, and
# that '$configure_ac' contains its name.
require_configure_ac=func_require_configure_ac
func_require_configure_ac ()
{
    $debug_cmd

    test -z "$configure_ac" \
      && func_autoconf_configure configure.ac && configure_ac=configure.ac
    test -z "$configure_ac" \
      && func_autoconf_configure configure.in && configure_ac=configure.in
    test -z "$configure_ac" \
      || func_verbose "found '$configure_ac'"

    require_configure_ac=:
}


# require_gnu_m4
# --------------
# Search for GNU M4, and export it in $M4.
require_gnu_m4=func_require_gnu_m4
func_require_gnu_m4 ()
{
    $debug_cmd

    test -n "$M4" || {
      # Find the first m4 binary that responds to --version.
      func_find_tool M4 gm4 gnum4 m4
    }

    test -n "$M4" || func_fatal_error "\
Please install GNU M4, or 'export M4=/path/to/gnu/m4'."

    func_verbose "export M4='$M4'"

    # Make sure the search result is visible to subshells
    export M4

    require_gnu_m4=:
}


## --------------- ##
## Core functions. ##
## --------------- ##

# This section contains the high level functions used when calling this
# file as a script. 'func_extract_trace' is probably the only one that you
# won't want to replace if you source this file into your own script.


# func_extract_trace MACRO_NAMES [FILENAME]...
# --------------------------------------------
# set '$func_extract_trace_result' to a colon delimited list of arguments
# to any of the comma separated list of MACRO_NAMES in FILENAME. If no
# FILENAME is given, then '$configure_ac' is assumed.
func_extract_trace ()
{
    $debug_cmd

    $require_configure_ac
    $require_gnu_m4

    _G_m4_traces=`$ECHO "--trace=$1" |$SED 's%,% --trace=%g'`
    _G_re_macros=`$ECHO "($1)" |$SED 's%,%|%g'`
    _G_macros="$1"; shift
    test $# -gt 0 || {
      set dummy $configure_ac
      shift
    }

    # Generate an error if the first file is missing
    <"$1"

    # Sadly, we can't use 'autom4te' tracing to extract macro arguments,
    # because it complains about things we want to ignore at bootstrap
    # time - like missing m4_include files; AC_PREREQ being newer than
    # the installed autoconf; and returns nothing when tracing
    # 'AM_INIT_AUTOMAKE' when aclocal hasn't been generated yet.
    #
    # The following tries to emulate a less persnickety version of (and
    # due to not having to wait for Perl startup on every invocation,
    # it's probably faster too):
    #
    #    autom4te --language=Autoconf --trace=$my_macro:\$% "$@"
    #
    # First we give a minimal set of macro declarations to M4 to prime
    # it for reading Autoconf macros, while still providing some of the
    # functionality generally used at m4-time to supply dynamic
    # arguments to Autocof functions, but without following
    # 'm4_s?include' files.
    _G_mini='
        dnl  Initialisation.
        m4_changequote([,])
        m4_define([m4_copy],   [m4_define([$2], m4_defn([$1]))])
        m4_define([m4_rename], [m4_copy([$1], [$2])m4_undefine([$1])])

        dnl  Replace macros which may abort m4 with a no-op variant.
        m4_pushdef([m4_assert])
        m4_pushdef([m4_exit])
        m4_pushdef([m4_fatal])
        m4_pushdef([m4_m4exit])

        dnl  Replace macros that might break stderr of m4.
        m4_pushdef([m4_errprint])
        m4_pushdef([m4_errprintn])
        m4_pushdef([m4_include])
        m4_pushdef([m4_warn])

        dnl  Avoid side-effects of tracing by extract-trace.
        m4_pushdef([m4_maketemp])
        m4_pushdef([m4_mkstemp])

        dnl  TODO: reasons for this
        m4_pushdef([m4_dnl])
        m4_pushdef([m4_m4wrap])

        dnl  Copy and rename macros not handled by "m4 --prefix".
        m4_define([dnl],         [m4_builtin([dnl])])
        m4_copy([m4_define],     [m4_defun])
        m4_rename([m4_ifelse],   [m4_if])
        m4_rename([m4_patsubst], [m4_bpatsubst])
        m4_rename([m4_regexp],   [m4_bregexp])

        dnl  "m4sugar.mini" - useful m4-time macros for dynamic arguments.
        dnl  If we discover packages that need more m4 macros defined in
        dnl  order to bootstrap correctly, add them here:
        m4_define([m4_bmatch],
            [m4_if([$#], 0, [], [$#], 1, [], [$#], 2, [$2],
                   [m4_if(m4_bregexp([$1], [$2]), -1,
                          [$0([$1], m4_shift3($@))], [$3])])])
        m4_define([m4_ifndef], [m4_ifdef([$1], [$3], [$2])])
        m4_define([m4_ifset],
            [m4_ifdef([$1], [m4_ifval(m4_defn([$1]), [$2], [$3])], [$3])])
        m4_define([m4_require], [$1])
        m4_define([m4_shift3], [m4_shift(m4shift(m4shift($@)))])

        dnl  "autoconf.mini" - things from autoconf macros we care about.
        m4_copy([m4_defun], [AC_DEFUN])

        dnl  Dummy definitions for the macros we want to trace.
        dnl  AM_INIT_AUTOMAKE at least produces no trace without this.
    '

    _G_save=$IFS
    IFS=,
    for _G_macro in $_G_macros; do
      IFS=$_G_save
      func_append _G_mini "AC_DEFUN([$_G_macro])$nl"
    done
    IFS=$_G_save

    # We discard M4's stdout, but the M4 trace output from reading our
    # "autoconf.mini" followed by any other files passed to this
    # function is then scanned by sed to transform it into a colon
    # delimited argument list assigned to a shell variable.
    _G_transform='s|#.*$||; s|^dnl .*$||; s| dnl .*$||;'

    # Unfortunately, alternation in regexp addresses doesn't work in at
    # least BSD (and hence Mac OS X) sed, so we have to append a capture
    # and print block for each traced macro to the sed transform script.
    _G_save=$IFS
    IFS=,
    for _G_macro in $_G_macros; do
      IFS=$_G_save
      func_append _G_transform '
        /^m4trace: -1- '"$_G_macro"'/ {
          s|^m4trace: -1- '"$_G_macro"'[([]*||
          s|], [[]|:|g
          s|[])]*$|:|
          s|\(.\):$|\1|
          p
        }'
    done
    IFS=$_G_save

    # Save the command pipeline results for further use by callers of
    # this function.
    func_extract_trace_result=`$ECHO "$_G_mini" \
      |$M4 -daq --prefix $_G_m4_traces - "$@" 2>&1 1>/dev/null \
      |$SED -n -e "$_G_transform"`
}


# func_extract_trace_first MACRO_NAMES [FILENAME]...
# --------------------------------------------------
# Exactly like func_extract_trace, except that only the first argument
# to the first invocation of one of the comma separated MACRO_NAMES is
# returned in '$func_extract_trace_first_result'.
func_extract_trace_first ()
{
    $debug_cmd

    func_extract_trace ${1+"$@"}
    func_extract_trace_first_result=`$ECHO "$func_extract_trace_result" \
      |$SED -e 's|:.*$||g' -e 1q`
}


# func_main [ARG]...
# ------------------
func_main ()
{
    $debug_cmd

    # Configuration.
    usage='$progname MACRO_NAME FILE [...]'

    long_help_message='
The first argument to this program is the name of an autotools macro
whose arguments you want to extract by examining the files listed in the
remaining arguments using the same tool that Autoconf and Automake use,
GNU M4.

The arguments are returned separated by colons, with each traced call
on a separate line.'

    # Option processing.
    func_options "$@"
    eval set dummy "$func_options_result"; shift

    # Validate remaining non-option arguments.
    test $# -gt 1 \
        || func_fatal_help "not enough arguments"

    # Pass non-option arguments to extraction function.
    func_extract_trace "$@"

    # Display results.
    test -n "$func_extract_trace_result" \
        && $ECHO "$func_extract_trace_result"

    # The End.
    exit $EXIT_SUCCESS
}


## --------------------------- ##
## Actually perform the trace. ##
## --------------------------- ##

# Only call 'func_main' if this script was called directly.
test extract-trace = "$progname" && func_main "$@"

# Local variables:
# mode: shell-script
# sh-indentation: 2
# eval: (add-hook 'before-save-hook 'time-stamp)
# time-stamp-pattern: "50/scriptversion=%:y-%02m-%02d.%02H; # UTC"
# time-stamp-time-zone: "UTC"
# End:
