1 package DBM::Deep::Engine;
5 use Fcntl qw( :DEFAULT :flock :seek );
9 # Open a fh to the database, create if nonexistent.
10 # Make sure file signature matches DBM::Deep spec.
15 if (defined($obj->_fh)) { $self->close( $obj ); }
18 local $SIG{'__DIE__'};
19 # Theoretically, adding O_BINARY should remove the need for the binmode
20 # Of course, testing it is going to be ... interesting.
21 my $flags = O_RDWR | O_CREAT | O_BINARY;
24 sysopen( $fh, $obj->_root->{file}, $flags )
26 $obj->_root->{fh} = $fh;
27 }; if ($@ ) { $obj->_throw_error( "Received error: $@\n" ); }
28 if (! defined($obj->_fh)) {
29 return $obj->_throw_error("Cannot sysopen file: " . $obj->_root->{file} . ": $!");
34 #XXX Can we remove this by using the right sysopen() flags?
35 # Maybe ... q.v. above
36 binmode $fh; # for win32
38 if ($obj->_root->{autoflush}) {
44 seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET);
47 my $bytes_read = read( $fh, $signature, length(DBM::Deep->SIG_FILE));
50 # File is empty -- write signature and master index
53 seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET);
54 print( $fh DBM::Deep->SIG_FILE);
55 $self->create_tag($obj, $obj->_base_offset, $obj->_type, chr(0) x $DBM::Deep::INDEX_SIZE);
57 my $plain_key = "[base]";
58 print( $fh pack($DBM::Deep::DATA_LENGTH_PACK, length($plain_key)) . $plain_key );
60 # Flush the filehandle
61 my $old_fh = select $fh;
62 my $old_af = $|; $| = 1; $| = $old_af;
65 my @stats = stat($fh);
66 $obj->_root->{inode} = $stats[1];
67 $obj->_root->{end} = $stats[7];
73 # Check signature was valid
75 unless ($signature eq DBM::Deep->SIG_FILE) {
77 return $obj->_throw_error("Signature not found -- file is not a Deep DB");
80 my @stats = stat($fh);
81 $obj->_root->{inode} = $stats[1];
82 $obj->_root->{end} = $stats[7];
85 # Get our type from master index signature
87 my $tag = $self->load_tag($obj, $obj->_base_offset);
89 #XXX We probably also want to store the hash algorithm name and not assume anything
90 #XXX The cool thing would be to allow a different hashing algorithm at every level
93 return $obj->_throw_error("Corrupted file, no master index record");
95 if ($obj->{type} ne $tag->{signature}) {
96 return $obj->_throw_error("File type mismatch");
106 if ( my $fh = $obj->_root->{fh} ) {
109 $obj->_root->{fh} = undef;
116 # Given offset, signature and content, create tag and write to disk
119 my ($obj, $offset, $sig, $content) = @_;
120 my $size = length($content);
124 seek($fh, $offset + $obj->_root->{file_offset}, SEEK_SET);
125 print( $fh $sig . pack($DBM::Deep::DATA_LENGTH_PACK, $size) . $content );
127 if ($offset == $obj->_root->{end}) {
128 $obj->_root->{end} += DBM::Deep->SIG_SIZE + $DBM::Deep::DATA_LENGTH_SIZE + $size;
134 offset => $offset + DBM::Deep->SIG_SIZE + $DBM::Deep::DATA_LENGTH_SIZE,
141 # Given offset, load single tag and return signature, size and data
144 my ($obj, $offset) = @_;
148 seek($fh, $offset + $obj->_root->{file_offset}, SEEK_SET);
149 if (eof $fh) { return undef; }
152 read( $fh, $b, DBM::Deep->SIG_SIZE + $DBM::Deep::DATA_LENGTH_SIZE );
153 my ($sig, $size) = unpack( "A $DBM::Deep::DATA_LENGTH_PACK", $b );
156 read( $fh, $buffer, $size);
161 offset => $offset + DBM::Deep->SIG_SIZE + $DBM::Deep::DATA_LENGTH_SIZE,
168 # Given index tag, lookup single entry in index and return .
171 my ($obj, $tag, $index) = @_;
173 my $location = unpack($DBM::Deep::LONG_PACK, substr($tag->{content}, $index * $DBM::Deep::LONG_SIZE, $DBM::Deep::LONG_SIZE) );
174 if (!$location) { return; }
176 return $self->load_tag( $obj, $location );