#!/usr/bin/perl
#
# Converts a git repository from hex to base32
#
use Compress::Zlib;
use Digest::SHA1 qw(sha1 sha1_hex);
use bytes;
$flat = 1; # Set to 1 to use flat base64 representation
sub sha1_base32($)
{
my($data) = @_;
my(@hash) = unpack("C*", sha1($data));
my($i, $c, $b, $v, $n);
my($out) = '';
die unless ( scalar(@hash) == 20 );
$b = 0;
$v = 0;
foreach $c ( @hash ) {
$v = ($v << 8) + $c;
$b += 8;
while ( $b >= 5 ) {
$b -= 5;
$n = ($v >> $b) & 0x1f;
$out .= substr("abcdefghijklmnopqrstuvwxyz234567", $n, 1);
}
}
die unless ( $b == 0 && length($out) == 32 );
return $out;
}
sub get_hex_file($$)
{
my($root, $hex) = @_;
my($h1) = substr($hex,0,2);
my($h2) = substr($hex,2);
my($data, @st, $sig);
open(HX, '<', "$root/$h1/$h2") or die "$0: $root/$h1/$h2: $!\n";
@st = stat(HX);
if ( read(HX, $data, $st[7]) != $st[7] ) {
die "$0: $root/$h1/$h2: read error: $!\n";
}
$sig = sha1_hex($data);
close(HX);
if ( $sig ne $hex ) {
die "$0: $root/$h1/$h2 doesn\'t match its own signature: $sig\n";
}
return $data;
}
sub write_file($$)
{
my($root, $data) = @_;
my($name) = sha1_base32($data);
$name =~ tr/\//_/; # Hybrid of regular and filesystem safe base64
my($pf);
if ( $flat ) {
$pf = $name;
} else {
my($px) = substr($name,0,2);
$pf = $px.'/'.substr($name,2);
mkdir("$root/$px", 0777);
}
open(WF, '>', "$root/$pf") or die "$0: $root/$pf: $!\n";
if ( !print WF $data ) {
die "$0: $root/$pf: write error: $!\n";
}
close(WF);
return $name;
}
sub handle_file($$$)
{
my($root, $newroot, $hex) = @_;
my($cdata, $data, $tdata, $odata, $object_type, $he);
$cdata = get_hex_file($root, $hex);
$data = uncompress($cdata);
if ( !defined($data) ) {
die "$0: $hex: failed to uncompress\n";
}
$data =~ /^((\S+) ([0-9]+)\0)/s;
$tdata = $1;
$odata = "$'";
$object_type = $2;
# Did we already do this file?
$he = $hash_equiv{$hex};
return $he if ( defined($he) );
if ( $object_type eq 'commit' ) {
while ( $odata =~ /^(\S+ )([0-9a-f]{40})$/m ) {
my($h) = $2;
my($pre) = $`.$1;
my($suf) = "$'";
# Make sure we process precedents
$he = handle_file($root, $newroot, $h);
if ( !defined($he) ) {
die "$0: unhandled hash: $h\n";
}
$odata = $pre.$he.$suf;
}
$cdata = compress($tdata.$odata, Z_BEST_COMPRESSION);
if ( !defined($data) ) {
die "$0: $hex: failed to compress\n";
}
}
$he = write_file($newroot, $cdata);
$hash_equiv{$hex} = $he;
return $he;
}
sub recurse($$)
{
my($root, $newroot) = @_;
my($i,$x,$e);
%hash_equiv = ();
for ( $i = 0 ; $i < 256 ; $i++ ) {
$x = sprintf("%02x", $i);
next unless ( opendir(RDIR, "$root/$x") );
while ( $e = readdir(RDIR) ) {
if ( $e =~ /^[0-9a-f]{38}$/ ) {
handle_file($root, $newroot, "$x$e");
}
}
closedir(RDIR);
}
}
($old_root, $new_root) = @ARGV;
mkdir($new_root, 0777) or die "$0: cannot mkdir $new_root: $!\n";
mkdir("$new_root/objects", 0777) or die "$0: cannot mkdir $new_root/objects: $!\n";
recurse("$old_root/objects", "$new_root/objects");
open(HEAD, '<', "$old_root/HEAD") or exit 0;
$head = <HEAD>;
chomp $head;
if ( defined($hash_equiv{$head}) ) {
$head = $hash_equiv{$head};
} else {
print STDERR "Warning: HEAD not found: $head\n";
exit 1;
}
close(HEAD);
open(NEWHEAD, '>', "$new_root/HEAD") or die "$0: cannot write new HEAD file\n";
print NEWHEAD $head, "\n";
close(NEWHEAD);