source: vendor/3.6.0/source4/script/minimal_includes.pl

#!/usr/bin/perl -w
# find a list of #include lines in C code that might not be needed
# usually called with something like this:
#    minimal_includes.pl `find . -name "*.c"`
# Andrew Tridgell <tridge@samba.org>

use strict;
use Data::Dumper;
use Getopt::Long;

my $opt_help = 0;
my $opt_remove = 0;
my $opt_skip_system = 0;
my $opt_waf = 0;

#####################################################################
# write a string into a file
sub FileSave($$)
{
    my($filename) = shift;
    my($v) = shift;
    local(*FILE);
    open(FILE, ">$filename") || die "can't open $filename";    
    print FILE $v;
    close(FILE);
}

sub load_lines($)
{
        my $fname = shift;
        my @lines = split(/^/m, `cat $fname`);
        return @lines;
}

sub save_lines($$)
{
        my $fname = shift;
        my $lines = shift;
        my $data = join('', @{$lines});
        FileSave($fname, $data);
}

sub test_compile($)
{
        my $fname = shift;
        my $obj;
        if ($opt_waf) {
                my $ret = `../buildtools/bin/waf $fname 2>&1`;
                return $ret
        }
        if ($fname =~ s/(.*)\..*$/$1.o/) {
                $obj = "$1.o";
        } else {
                return "NOT A C FILE";
        }
        unlink($obj);
        my $ret = `make $obj 2>&1`;
        if (!unlink("$obj")) {
                return "COMPILE FAILED";
        }
        return $ret;
}

sub test_include($$$$)
{
        my $fname = shift;
        my $lines = shift;
        my $i = shift;
        my $original = shift;
        my $line = $lines->[$i];
        my $testfname;

        $lines->[$i] = "";

        my $mname = $fname . ".misaved";

        unlink($mname);
        rename($fname, $mname) || die "failed to rename $fname";
        save_lines($fname, $lines);
        
        my $out = test_compile($fname);

        if ($out eq $original) {
                if ($opt_remove) {
                        if ($opt_skip_system && 
                            $line =~ /system\//) {
                                print "$fname: not removing system include $line\n";
                        } else {
                                print "$fname: removing $line\n";
                                unlink($mname);
                                return;
                        }
                } else {
                        print "$fname: might be able to remove $line\n";
                }
        }

        $lines->[$i] = $line;
        rename($mname, $fname) || die "failed to restore $fname";
}

sub process_file($)
{
        my $fname = shift;
        my @lines = load_lines($fname);
        my $num_lines = $#lines;

        my $original = test_compile($fname);

        if ($original eq "COMPILE FAILED") {
                print "Failed to compile $fname\n";
                return;
        }

        print "Processing $fname (with $num_lines lines)\n";
        
        my $if_level = 0;

        for (my $i=0;$i<=$num_lines;$i++) {
                my $line = $lines[$i];
                if ($line =~ /^\#\s*if/) {
                        $if_level++;
                }
                if ($line =~ /^\#\s*endif/) {
                        $if_level--;
                }
                if ($if_level == 0 &&
                    $line =~ /^\#\s*include/ && 
                    !($line =~ /needed/)) {
                        test_include($fname, \@lines, $i, $original);
                }
        }
}


#########################################
# display help text
sub ShowHelp()
{
    print "
           minimise includes
           Copyright (C) tridge\@samba.org

           Usage: minimal_includes.pl [options] <C files....>
           
           Options:
                 --help         show help
                 --remove       remove includes, don't just list them
                 --skip-system  don't remove system/ includes
                 --waf          use waf target conventions
";
}


# main program
GetOptions (
            'h|help|?' => \$opt_help,
            'remove' => \$opt_remove,
            'skip-system' => \$opt_skip_system,
            'waf' => \$opt_waf,
            );

if ($opt_help) {
        ShowHelp();
        exit(0);
}

for (my $i=0;$i<=$#ARGV;$i++) {
        my $fname = $ARGV[$i];
        process_file($fname);
}