--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/fuse	Tue Jul 12 00:21:58 2011 +0200
@@ -0,0 +1,157 @@
+#! /usr/bin/perl
+
+use 5.010;
+use strict;
+use warnings;
+use autodie qw(:all);
+
+use Fuse;
+
+my $src = shift // die "need source directory\n";
+my $mp = shift // die "need mountpoint\n";
+
+$fs::DATA = "$src/data";
+$fs::IDX = "$src/idx";
+
+Fuse::main(mountpoint => $mp,
+    debug => 0,
+    getattr => "fs::getattr",
+    getdir => "fs::getdir",
+    open => "fs::openfile",
+    read => "fs::readbuffer",
+    write => "fs::writebuffer",
+    );
+
+
+{ package fs;
+  use strict;
+  use warnings;
+  use POSIX qw(:errno_h);
+  use autodie qw(:all);
+
+  our ($ROOT, $DATA, $IDX);
+  my %FILE;
+  my %CACHE;
+
+    sub getattr {
+	my $path = $IDX . shift;
+	return stat $path if $path eq "$IDX/";
+	# rest are the idx
+	my @attr = stat $path or return -(ENOENT);
+	my %meta = _get_meta($path);
+	$attr[7] = $meta{devsize};
+	$attr[9] = $meta{timestamp};
+	$attr[2] &= ~0222;		# r/o
+	return @attr;
+    }
+
+    sub getdir {
+	my $path = $IDX . shift;
+	opendir(my $dh, $path) or return 0;
+	return (readdir($dh), 0);
+    }
+
+
+    sub openfile {
+	my $path = $IDX . shift;
+	return 0 if exists $FILE{$path};
+	$FILE{$path}{meta} = { _get_meta($path) };
+	$FILE{$path}{blocklist} = {};
+
+	open(my $fh => $path);
+	{   # the file header
+	    local $/ = "";
+	    scalar <$fh>;
+	}
+	while (<$fh>) {
+	    /^#/ and last;
+	    my ($block, $cs, $file) = split;
+	    $block-- if not $FILE{$path}{meta}{format};
+	    $FILE{$path}{blocklist}{$block} = $file;
+	}
+	return 0;
+    }
+
+    sub readbuffer {
+	my $path = $IDX . shift;
+	my ($size, $offset) = @_;
+	my $finfo = $FILE{$path} or die "File $path is not opened!";
+	return "" if $offset >= $finfo->{meta}{devsize};
+
+	my $buffer = "";
+	for (my $need = $size; $need; $need = $size - length($buffer)) {
+	    $buffer .= _readblock($finfo, $need, $offset + length($buffer));
+	}
+
+	return $buffer;
+    }
+
+    sub _readblock {
+	my ($finfo, $size, $offset) = @_;
+
+	my $block = int($offset / $finfo->{meta}{blocksize});
+	my $blockoffset = $offset % $finfo->{meta}{blocksize};
+
+	my $length = $finfo->{meta}{blocksize} - $blockoffset;
+	$length = $size if $size <= $length;
+
+	if (exists $CACHE{$finfo}{$block}) {
+	    return substr $CACHE{$finfo}{$block}, $blockoffset, $length;
+	}
+
+	open(my $fh => "$DATA/" . $finfo->{blocklist}{$block});
+	seek($fh => $blockoffset, 0) or die "seek: $!";
+	local $/ = \$length;
+	return scalar <$fh>;
+    }
+
+    sub writebuffer {
+	my $path = $IDX . shift;
+	my ($buffer, $offset) = @_;
+	my $size = length($buffer);
+	my $finfo = $FILE{$path} or die "File $path is not opened!";
+
+	my $written = 0;
+	while ($written < $size) {
+	     my $n = _writeblock($finfo, substr($buffer, $written), $offset + $written); 
+	     return $written if not $n;
+	     $written += $n;
+	}
+	return $size;
+    }
+
+    sub _writeblock {
+	my ($finfo, $buffer, $offset) = @_;
+	my $size = length($buffer);
+
+	my $block = int($offset / $finfo->{meta}{blocksize});
+	my $blockoffset = $offset % $finfo->{meta}{blocksize};
+
+	if (not exists $CACHE{$finfo}{$block}) {
+	    open(my $fh => "$DATA/" . $finfo->{blocklist}{$block});
+	    local $/ = undef;
+	    $CACHE{$finfo}{$block} = <$fh>;
+	    close($fh);
+	}
+
+	my $length = $finfo->{meta}{blocksize} - $blockoffset;
+	$length = $size if $size <= $length;
+
+	substr($CACHE{$finfo}{$block}, $blockoffset, $length)
+	    = substr($buffer, 0, $length);
+
+	return $length;
+    }
+
+    sub _get_meta {
+	my $path = shift;
+	my %meta;
+	open(my $fh => $path);
+	while(<$fh>) {
+	    last if /^$/;
+	    /^(?<k>\S+):\s+(?<v>.*?)\s*$/ and do { $meta{$+{k}} = $+{v}; next; };
+	}
+	return %meta;
+    }
+
+}