linuxboot/bin/nvram-compact

#!/usr/bin/perl
# Remove invalid and non-data entries from an NVRAM section
# This only handles the common cases

use strict;
use warnings;
use FindBin;
use lib "$FindBin::Bin/../lib";
use EFI;
use Getopt::Long;
use File::Basename;
use File::Temp 'tempfile';
use Data::Dumper;

my $nvram_guid = "cef5b9a3-476d-497f-9fdc-e98143e0422c";
my $verbose = 0;

local $/;
my $ffs = <>;

my $file_guid = EFI::read_guid($ffs, 0x00);
die "$file_guid != nvram guid $nvram_guid\n"
	unless $file_guid eq $nvram_guid;

# should check for FFS header 2, as well as confirm length
my $offset = 0x18;
my $ffs_hdr = substr($ffs, 0x00, $offset);
my $ffs_len = length($ffs);
my $data = '';



while($offset < $ffs_len - 0x08)
{
	my $nvar = EFI::NVRAM::NVAR->parse($ffs, $offset)
		or last;

	$offset += $nvar->length();

	# Decide if we keep it:
	# No valid bit? do not keep
	next unless $nvar->valid();

	# if this is not an ASCII name variable
	# we probably have already copied its data by
	# following the linked list
	my $name = $nvar->name()
		or next;
	my $guid = $nvar->guid();
	my $attr = $nvar->{attr};

	# Linked? Superceded. We don't want to keep it
	# but we need to follow the linked list to
	# find the latest version of the data

	while(1)
	{
		my $next = $nvar->next()
			or last;

		$nvar = EFI::NVRAM::NVAR->parse($ffs, $next);

		die sprintf "offset 0x%x: next failed?\n", $next
			unless $nvar;

		die sprintf "offset 0x%x: nvar is not valid?\n", $next
			unless $nvar->valid();
	}

	# Replace the name and guid with that of our first one
	# in the linked list of nvars
	$nvar->{name} = $name;
	$nvar->{guid} = $guid;
	$nvar->{attr} = $attr;

	warn "$name\n"
		if $verbose;

	$data .= $nvar->output();
}

# Create the new FFS and pad it to the end
my $new_ffs = $ffs_hdr . $data;
$new_ffs .= chr(0xFF) x ($ffs_len - length($new_ffs));

# Look to see if there is a GUID store?
while($offset < $ffs_len)
{
	if (substr($ffs, $offset, 1) eq chr(0xFF))
	{
		$offset++;
		next;
	}

	# Non-empty space. copy it to the end
	warn sprintf "offset 0x%x: GUID store found\n", $offset;
	my $guid_store = substr($ffs, $offset);
	substr($new_ffs, $offset) = $guid_store;
	last;
}


print $new_ffs;