mirror of
https://github.com/linuxboot/heads.git
synced 2024-12-18 20:47:55 +00:00
151 lines
3.6 KiB
Perl
Executable File
151 lines
3.6 KiB
Perl
Executable File
#!/usr/bin/perl
|
|
# Clean all non-deterministric fields in a newc cpio file
|
|
#
|
|
# Items fixed:
|
|
# Files are sorted by name
|
|
# Inode numbers are based on the hash of the filename
|
|
# File timestamp is set to 1970-01-01T00:00:00
|
|
# uid/gid are set to root
|
|
# check field is zeroed
|
|
# nlinks is set to zero, since the filesystem manages it
|
|
#
|
|
use warnings;
|
|
use strict;
|
|
use Data::Dumper;
|
|
use Digest::MD5 'md5_hex';
|
|
|
|
# struct cpio_newc_header {
|
|
# char c_magic[6]; -6
|
|
# char c_ino[8]; -- set to a monotonic value 0
|
|
# char c_mode[8]; 8
|
|
# char c_uid[8]; 16
|
|
# char c_gid[8]; 24
|
|
# char c_nlink[8]; 32
|
|
# char c_mtime[8]; 40 -- set to zero
|
|
# char c_filesize[8]; 48
|
|
# char c_devmajor[8]; 56
|
|
# char c_devminor[8]; 64
|
|
# char c_rdevmajor[8]; 72
|
|
# char c_rdevminor[8]; 80
|
|
# char c_namesize[8]; 88
|
|
# char c_check[8]; 96
|
|
# }; // 104
|
|
# followed by namesize bytes of name (padded to be a multiple of 4)
|
|
# followed dby filesize bytes of file (padded to be a multiple of 4)
|
|
|
|
# Read the entire file at once
|
|
undef $/;
|
|
|
|
# Generate a map of all of the files in the cpio archive
|
|
# This will also merge multiple cpio files
|
|
my %entries;
|
|
my $trailer;
|
|
|
|
while(<>)
|
|
{
|
|
for(my $i = 0 ; $i < length $_ ; )
|
|
{
|
|
my $magic = substr($_, $i, 6);
|
|
if ($magic ne "070701")
|
|
{
|
|
die "$ARGV: offset $i: invalid magic '$magic'\n";
|
|
}
|
|
|
|
my $namesize = substr($_, $i + 6+88, 8);
|
|
my $filesize = substr($_, $i + 6+48, 8);
|
|
|
|
if ($namesize =~ /[^0-9A-Fa-f]/)
|
|
{
|
|
die "$ARGV: offset $i: invalid characters in namesize '$namesize'\n";
|
|
}
|
|
|
|
if ($filesize =~ /[^0-9A-Fa-f]/)
|
|
{
|
|
die "$ARGV: offset $i: invalid characters in filesize '$filesize'\n";
|
|
}
|
|
|
|
# Convert them to hex
|
|
$namesize = hex $namesize;
|
|
$filesize = hex $filesize;
|
|
|
|
#print STDERR "name: '$namesize', filesize: '$filesize'\n";
|
|
|
|
my $name = substr($_, $i + 6+104, $namesize);
|
|
#print STDERR Dumper($name);
|
|
|
|
# Align the header size to be a multiple of four bytes
|
|
my $entry_size = (6+104 + $namesize + 3) & ~3;
|
|
$entry_size += ($filesize + 3) & ~3;
|
|
|
|
my $entry = substr($_, $i, $entry_size);
|
|
$i += $entry_size;
|
|
|
|
if ($name =~ /^TRAILER!!!/)
|
|
{
|
|
$trailer = $entry;
|
|
last;
|
|
}
|
|
|
|
$entries{$name} = $entry;
|
|
}
|
|
|
|
die "$ARGV: No trailer!\n" unless $trailer;
|
|
}
|
|
|
|
# Apply the cleaning to each one
|
|
for my $filename (sort keys %entries)
|
|
{
|
|
my $entry = $entries{$filename};
|
|
my $zero = sprintf "%08x", 0;
|
|
|
|
# inodes are hashed to be deterministic
|
|
# and hopefully not colliding
|
|
my $md5 = md5_hex($filename);
|
|
my $d0 = hex substr($md5, 0, 8) ;
|
|
my $d1 = hex substr($md5, 8, 8) ;
|
|
my $d2 = hex substr($md5, 16, 8) ;
|
|
my $d3 = hex substr($md5, 24, 8) ;
|
|
my $hash = sprintf "%08x", $d0 ^ $d1 ^ $d2 ^ $d3;
|
|
|
|
#warn "$filename: $md5 -> $hash\n";
|
|
substr($entry, 6 + 0, 8) = $hash;
|
|
|
|
# set timestamps to zero
|
|
substr($entry, 6 + 40, 8) = $zero;
|
|
|
|
# remove group/user permissions, leaving only
|
|
# the owner bits intact.
|
|
my $mode = hex substr($entry, 6 + 8, 8);
|
|
$mode &= ~0077;
|
|
#$mode |= $mode >> 3 | $mode >> 6;
|
|
substr($entry, 6 + 8, 8) = sprintf "%08X", $mode;
|
|
|
|
# set uid/gid to zero
|
|
substr($entry, 6 + 16, 8) = $zero;
|
|
substr($entry, 6 + 24, 8) = $zero;
|
|
|
|
# zero out the nlinks, since it is managed by the real fs
|
|
substr($entry, 6 + 32, 8) = $zero;
|
|
|
|
# set the device major/minor to zero
|
|
substr($entry, 6 + 56, 8) = $zero;
|
|
substr($entry, 6 + 64, 8) = $zero;
|
|
|
|
# set check to zero
|
|
substr($entry, 6 + 96, 8) = $zero;
|
|
|
|
$entries{$filename} = $entry;
|
|
}
|
|
|
|
|
|
# Print them in sorted order
|
|
for my $filename (sort keys %entries)
|
|
{
|
|
my $entry = $entries{$filename};
|
|
print $entry;
|
|
}
|
|
|
|
# Output the trailer to mark the end of the archive
|
|
print $trailer;
|
|
__END__
|