9 use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
16 our $VERSION = '0.04';
20 Fuse::DBI - mount your database as filesystem and use it
25 Fuse::DBI->mount( ... );
27 See C<run> below for examples how to set parameters.
31 This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
32 available at L<http://sourceforge.net/projects/avf> to mount
33 your database as file system.
35 That will give you possibility to use normal file-system tools (cat, grep, vi)
36 to manipulate data in database.
38 It's actually opposite of Oracle's intention to put everything into database.
47 Mount your database as filesystem.
49 Let's suppose that your database have table C<files> with following structure:
57 Following is example how to mount table like that to C</mnt>:
59 my $mnt = Fuse::DBI->mount({
60 'filenames' => 'select id,filename,size,writable from files',
61 'read' => 'select content from files where id = ?',
62 'update' => 'update files set content = ? where id = ?',
63 'dsn' => 'DBI:Pg:dbname=test_db',
64 'user' => 'database_user',
65 'password' => 'database_password',
66 'invalidate' => sub { ... },
75 SQL query which returns C<id> (unique id for that row), C<filename>,
76 C<size> and C<writable> boolean flag.
80 SQL query which returns only one column with content of file and has
81 placeholder C<?> for C<id>.
85 SQL query with two pace-holders, one for new content and one for C<id>.
89 C<DBI> dsn to connect to (contains database driver and name of database).
93 User with which to connect to database
97 Password for connecting to database
101 Optional anonymous code reference which will be executed when data is updated in
102 database. It can be used as hook to delete cache (for example on-disk-cache)
103 which is created from data edited through C<Fuse::DBI>.
107 Optional flag which forks after mount so that executing script will continue
108 running. Implementation is experimental.
119 sub fuse_module_loaded;
121 # evil, evil way to solve this. It makes this module non-reentrant. But, since
122 # fuse calls another copy of this script for each mount anyway, this shouldn't
129 bless($self, $class);
135 carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
136 carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
138 # save (some) arguments in self
139 foreach (qw(mount invalidate)) {
140 $self->{$_} = $arg->{$_};
143 foreach (qw(filenames read update)) {
144 carp "mount needs '$_' SQL" unless ($arg->{$_});
147 $ctime_start = time();
150 if ($arg->{'fork'}) {
152 die "fork() failed: $!" unless defined $pid;
153 # child will return to caller
159 $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
161 $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
163 $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
164 $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
167 $self->{'sth'} = $sth;
169 $self->{'read_filenames'} = sub { $self->read_filenames };
170 $self->read_filenames;
172 $self->{'mounted'} = 1;
177 mountpoint=>$arg->{'mount'},
178 getattr=>\&e_getattr,
185 truncate=>\&e_truncate,
191 $self->{'mounted'} = 0;
193 exit(0) if ($arg->{'fork'});
201 Unmount your database as filesystem.
205 This will also kill background process which is translating
206 database to filesystem.
213 if ($self->{'mounted'}) {
214 system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
221 print STDERR "umount called by SIG INT\n";
227 return if (! $self->{'mounted'});
228 print STDERR "umount called by DESTROY\n";
232 =head2 fuse_module_loaded
234 Checks if C<fuse> module is loaded in kernel.
236 die "no fuse module loaded in kernel"
237 unless (Fuse::DBI::fuse_module_loaded);
239 This function in called by C<mount>, but might be useful alone also.
243 sub fuse_module_loaded {
245 die "can't start lsmod: $!" unless ($lsmod);
246 if ($lsmod =~ m/fuse/s) {
259 my $sth = $self->{'sth'} || die "no sth argument";
261 # create empty filesystem
268 # cont => "File 'a'.\n",
270 # ctime => time()-2000
274 # fetch new filename list from database
275 $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
277 # read them in with sesible defaults
278 while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
279 $files{$row->{'filename'}} = {
280 size => $row->{'size'},
281 mode => $row->{'writable'} ? 0644 : 0444,
282 id => $row->{'id'} || 99,
286 foreach (split(m!/!, $row->{'filename'})) {
287 # first, entry is assumed to be file
308 print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
315 $file = '.' unless length($file);
320 my ($file) = filename_fixup(shift);
322 $file = '.' unless length($file);
323 return -ENOENT() unless exists($files{$file});
324 my ($size) = $files{$file}{size} || 1;
325 my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);
326 my ($atime, $ctime, $mtime);
327 $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
329 my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
331 # 2 possible types of return values:
332 #return -ENOENT(); # or any other error you care to
333 #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n");
334 return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
338 my ($dirname) = shift;
340 # return as many text filenames as you like, followed by the retval.
341 print((scalar keys %files)." files total\n");
343 foreach my $f (sort keys %files) {
345 if ($f =~ s/^\E$dirname\Q\///) {
346 $out{$f}++ if ($f =~ /^[^\/]+$/);
349 $out{$f}++ if ($f =~ /^[^\/]+$/);
353 $out{'no files? bug?'}++;
355 print scalar keys %out," files in dir '$dirname'\n";
356 print "## ",join(" ",keys %out),"\n";
357 return (keys %out),0;
363 die "read_content needs file and id" unless ($file && $id);
365 $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
366 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
367 $files{$file}{ctime} = time();
368 print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
373 # VFS sanity check; it keeps all the necessary state, not much to do here.
374 my $file = filename_fixup(shift);
377 return -ENOENT() unless exists($files{$file});
378 return -EISDIR() unless exists($files{$file}{id});
380 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
382 print "open '$file' ",length($files{$file}{cont})," bytes\n";
387 # return an error numeric, or binary/text string.
388 # (note: 0 means EOF, "0" will give a byte (ascii "0")
389 # to the reading program)
390 my ($file) = filename_fixup(shift);
391 my ($buf_len,$off) = @_;
393 return -ENOENT() unless exists($files{$file});
395 my $len = length($files{$file}{cont});
397 print "read '$file' [$len bytes] offset $off length $buf_len\n";
399 return -EINVAL() if ($off > $len);
400 return 0 if ($off == $len);
402 $buf_len = $len-$off if ($len - $off < $buf_len);
404 return substr($files{$file}{cont},$off,$buf_len);
408 print "transaction rollback\n";
409 $dbh->rollback || die $dbh->errstr;
410 print "invalidate all cached content\n";
411 foreach my $f (keys %files) {
412 delete $files{$f}{cont};
414 print "begin new transaction\n";
415 #$dbh->begin_work || die $dbh->errstr;
420 my $file = shift || die;
422 $files{$file}{ctime} = time();
429 if (!$sth->{'update'}->execute($cont,$id)) {
430 print "update problem: ",$sth->{'update'}->errstr;
434 if (! $dbh->commit) {
435 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
439 print "updated '$file' [",$files{$file}{id},"]\n";
441 $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
447 my $file = filename_fixup(shift);
448 my ($buffer,$off) = @_;
450 return -ENOENT() unless exists($files{$file});
452 my $cont = $files{$file}{cont};
453 my $len = length($cont);
455 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
457 $files{$file}{cont} = "";
459 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
460 $files{$file}{cont} .= $buffer;
461 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
463 $files{$file}{size} = length($files{$file}{cont});
465 if (! update_db($file)) {
468 return length($buffer);
473 my $file = filename_fixup(shift);
476 print "truncate to $size\n";
478 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
479 $files{$file}{size} = $size;
485 my ($atime,$mtime,$file) = @_;
486 $file = filename_fixup($file);
488 return -ENOENT() unless exists($files{$file});
490 print "utime '$file' $atime $mtime\n";
492 $files{$file}{time} = $mtime;
496 sub e_statfs { return 255, 1, 1, 1, 1, 2 }
499 my $file = filename_fixup(shift);
501 if (exists( $dirs{$file} )) {
502 print "unlink '$file' will re-read template names\n";
503 print Dumper($fuse_self);
504 $$fuse_self->{'read_filenames'}->();
506 } elsif (exists( $files{$file} )) {
507 print "unlink '$file' will invalidate cache\n";
508 read_content($file,$files{$file}{id});
523 C<FUSE (Filesystem in USErspace)> website
524 L<http://sourceforge.net/projects/avf>
526 Example for WebGUI which comes with this distribution in
527 directory C<examples/webgui.pl>. It also contains a lot of documentation
528 about design of this module, usage and limitations.
532 Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
534 =head1 COPYRIGHT AND LICENSE
536 Copyright (C) 2004 by Dobrica Pavlinusic
538 This library is free software; you can redistribute it and/or modify
539 it under the same terms as Perl itself, either Perl version 5.8.4 or,
540 at your option, any later version of Perl 5 you may have available.