r5321: added a program that works out the minimal set of #include lines

needed for a C file in Samba. It tries compiling without each #include
line in turn, and looks for any changes in the compiler output.

Note that the output is not guaranteed correct, it might be that an
include is needed onlyu on some platforms. To cope with this, it
doesn't consider lines with the word "needed" on them. So add a
comment like this:

#include "foo.h" /* needed by systems without kerberos */

and it will know to skip it

It also skips any include lines in a #if section.

If you are brave, you can give it the option --remove and it will
remove lines it thinks are not needed. Please review carefully before
committing the results, and watch the build farm for breakage.

source/script/minimal_includes.pl

@@ -0,0 +1,150 @@
+#!/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;
+
+#####################################################################
+# 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 $obj;
+	if ($fname =~ s/(.*)\.c$/$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];
+
+	$lines->[$i] = "";
+	save_lines("_testcompile.c", $lines);
+	
+	my $out = test_compile("_testcompile.c");
+	$out =~ s/_testcompile.c/$fname/g;
+
+	if ($out eq $original) {
+		if ($opt_remove) {
+			print "$fname: removing $line\n";
+			save_lines($fname, $lines);
+			return;
+		}
+		print "$fname: might be able to remove $line\n";
+	}
+
+	$lines->[$i] = $line;
+	unlink("_testcompile.c");
+}
+
+sub process_file($)
+{
+	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, $original);
+		}
+	}
+}
+
+
+#########################################
+# display help text
+sub ShowHelp()
+{
+    print "
+           minimise includes
+           Copyright (C) tridge\@samba.org
+
+	   Usage: minimal_includes.pl [options] <C files....>
+	   
+	   Options:
+                 --help       show help
+                 --remove     remove includes, don't just list them
+";
+}
+
+
+# main program
+GetOptions (
+	    'h|help|?' => \$opt_help,
+	    'remove' => \$opt_remove,
+	    );
+
+if ($opt_help) {
+	ShowHelp();
+	exit(0);
+}
+
+for (my $i=0;$i<=$#ARGV;$i++) {
+	my $fname = $ARGV[$i];
+	process_file($fname);
+}