source: vendor/3.6.0/script/findstatic.pl

#!/usr/bin/perl -w
# find a list of fns and variables in the code that could be static
# usually called with something like this:
#    findstatic.pl `find . -name "*.o"`
# Andrew Tridgell <tridge@samba.org>

use strict;

# use nm to find the symbols
my($saved_delim) = $/;
undef $/;
my($syms) = `nm -o @ARGV`;
$/ = $saved_delim;

my(@lines) = split(/\n/s, $syms);

my(%def);
my(%undef);
my(%stype);

my(%typemap) = (
               "T" => "function",
               "C" => "uninitialised variable",
               "D" => "initialised variable"
                );


# parse the symbols into defined and undefined 
for (my($i)=0; $i <= $#{@lines}; $i++) {
        my($line) = $lines[$i];
        if ($line =~ /(.*):[a-f0-9]* ([TCD]) (.*)/) {
                my($fname) = $1;
                my($symbol) = $3;
                push(@{$def{$fname}}, $symbol);
                $stype{$symbol} = $2;
        }
        if ($line =~ /(.*):\s* U (.*)/) {
                my($fname) = $1;
                my($symbol) = $2;
                push(@{$undef{$fname}}, $symbol);
        }
}

# look for defined symbols that are never referenced outside the place they 
# are defined
foreach my $f (keys %def) {
        print "Checking $f\n";
        my($found_one) = 0;
        foreach my $s (@{$def{$f}}) {
                my($found) = 0;
                foreach my $f2 (keys %undef) {
                        if ($f2 ne $f) {
                                foreach my $s2 (@{$undef{$f2}}) {
                                        if ($s2 eq $s) {
                                                $found = 1;
                                                $found_one = 1;
                                        }
                                }
                        }
                }
                if ($found == 0) {
                        my($t) = $typemap{$stype{$s}};
                        print "  '$s' is unique to $f  ($t)\n";
                }
        }
        if ($found_one == 0) {
                print "  all symbols in '$f' are unused (main program?)\n";
        }
}