9 use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
15 our $VERSION = '0.07';
17 # block size for this filesystem
18 use constant BLOCK => 1024;
22 Fuse::DBI - mount your database as filesystem and use it
27 Fuse::DBI->mount( ... );
29 See C<run> below for examples how to set parameters.
33 This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
34 available at L<http://fuse.sourceforge.net/> to mount
35 your database as file system.
37 That will give you possibility to use normal file-system tools (cat, grep, vi)
38 to manipulate data in database.
40 It's actually opposite of Oracle's intention to put everything into database.
49 Mount your database as filesystem.
51 Let's suppose that your database have table C<files> with following structure:
59 Following is example how to mount table like that to C</mnt>:
61 my $mnt = Fuse::DBI->mount({
62 'filenames' => 'select id,filename,size,writable from files',
63 'read' => 'select content from files where id = ?',
64 'update' => 'update files set content = ? where id = ?',
65 'dsn' => 'DBI:Pg:dbname=test_db',
66 'user' => 'database_user',
67 'password' => 'database_password',
68 'invalidate' => sub { ... },
77 SQL query which returns C<id> (unique id for that row), C<filename>,
78 C<size> and C<writable> boolean flag.
82 SQL query which returns only one column with content of file and has
83 placeholder C<?> for C<id>.
87 SQL query with two pace-holders, one for new content and one for C<id>.
91 C<DBI> dsn to connect to (contains database driver and name of database).
95 User with which to connect to database
99 Password for connecting to database
103 Optional anonymous code reference which will be executed when data is updated in
104 database. It can be used as hook to delete cache (for example on-disk-cache)
105 which is created from data edited through C<Fuse::DBI>.
109 Optional flag which forks after mount so that executing script will continue
110 running. Implementation is experimental.
121 sub fuse_module_loaded;
123 # evil, evil way to solve this. It makes this module non-reentrant. But, since
124 # fuse calls another copy of this script for each mount anyway, this shouldn't
131 bless($self, $class);
137 unless ($self->fuse_module_loaded) {
138 print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n";
139 system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n";
142 carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
143 carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
145 # save (some) arguments in self
146 foreach (qw(mount invalidate)) {
147 $self->{$_} = $arg->{$_};
150 foreach (qw(filenames read update)) {
151 carp "mount needs '$_' SQL" unless ($arg->{$_});
154 $ctime_start = time();
157 if ($arg->{'fork'}) {
159 die "fork() failed: $!" unless defined $pid;
160 # child will return to caller
163 while ($counter && ! $self->is_mounted) {
164 select(undef, undef, undef, 0.5);
167 if ($self->is_mounted) {
175 $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
177 $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
179 $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
180 $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
183 $self->{'sth'} = $sth;
185 $self->{'read_filenames'} = sub { $self->read_filenames };
186 $self->read_filenames;
191 mountpoint=>$arg->{'mount'},
192 getattr=>\&e_getattr,
199 truncate=>\&e_truncate,
205 exit(0) if ($arg->{'fork'});
213 Check if fuse filesystem is mounted
215 if ($mnt->is_mounted) { ... }
223 my $mount = $self->{'mount'} || confess "can't find mount point!";
224 if (open(MTAB, "/etc/mtab")) {
226 $mounted = 1 if (/ $mount fuse /i);
230 warn "can't open /etc/mtab: $!";
239 Unmount your database as filesystem.
243 This will also kill background process which is translating
244 database to filesystem.
251 if ($self->{'mount'} && $self->is_mounted) {
252 system "( fusermount -u ".$self->{'mount'}." 2>&1 ) >/dev/null";
253 if ($self->is_mounted) {
254 system "sudo umount ".$self->{'mount'} ||
264 if ($fuse_self && $$fuse_self->umount) {
265 print STDERR "umount called by SIG INT\n";
270 if ($fuse_self && $$fuse_self->umount) {
271 print STDERR "umount called by SIG QUIT\n";
278 print STDERR "umount called by DESTROY\n";
282 =head2 fuse_module_loaded
284 Checks if C<fuse> module is loaded in kernel.
286 die "no fuse module loaded in kernel"
287 unless (Fuse::DBI::fuse_module_loaded);
289 This function in called by C<mount>, but might be useful alone also.
293 sub fuse_module_loaded {
295 die "can't start lsmod: $!" unless ($lsmod);
296 if ($lsmod =~ m/fuse/s) {
308 my $sth = $self->{'sth'} || die "no sth argument";
310 # create empty filesystem
321 # cont => "File 'a'.\n",
323 # ctime => time()-2000
327 # fetch new filename list from database
328 $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
330 # read them in with sesible defaults
331 while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
332 $files{$row->{'filename'}} = {
333 size => $row->{'size'},
334 mode => $row->{'writable'} ? 0644 : 0444,
335 id => $row->{'id'} || 99,
339 foreach (split(m!/!, $row->{'filename'})) {
340 # first, entry is assumed to be file
360 print "found ",scalar(keys %files)," files\n";
367 $file = '.' unless length($file);
372 my ($file) = filename_fixup(shift);
374 $file = '.' unless length($file);
375 return -ENOENT() unless exists($files{$file});
376 my ($size) = $files{$file}{size} || BLOCK;
377 my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+BLOCK-1)/BLOCK),0,0,1,BLOCK);
378 my ($atime, $ctime, $mtime);
379 $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
381 my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
383 # 2 possible types of return values:
384 #return -ENOENT(); # or any other error you care to
385 #print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n";
386 return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
390 my ($dirname) = shift;
392 # return as many text filenames as you like, followed by the retval.
393 print((scalar keys %files)." files total\n");
395 foreach my $f (sort keys %files) {
397 if ($f =~ s/^\Q$dirname\E\///) {
398 $out{$f}++ if ($f =~ /^[^\/]+$/);
401 $out{$f}++ if ($f =~ /^[^\/]+$/);
405 $out{'no files? bug?'}++;
407 print scalar keys %out," files in dir '$dirname'\n";
408 print "## ",join(" ",keys %out),"\n";
409 return (keys %out),0;
415 die "read_content needs file and id" unless ($file && $id);
417 $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
418 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
419 # I should modify ctime only if content in database changed
420 #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
421 print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
426 # VFS sanity check; it keeps all the necessary state, not much to do here.
427 my $file = filename_fixup(shift);
430 return -ENOENT() unless exists($files{$file});
431 return -EISDIR() unless exists($files{$file}{id});
433 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
435 print "open '$file' ",length($files{$file}{cont})," bytes\n";
440 # return an error numeric, or binary/text string.
441 # (note: 0 means EOF, "0" will give a byte (ascii "0")
442 # to the reading program)
443 my ($file) = filename_fixup(shift);
444 my ($buf_len,$off) = @_;
446 return -ENOENT() unless exists($files{$file});
448 my $len = length($files{$file}{cont});
450 print "read '$file' [$len bytes] offset $off length $buf_len\n";
452 return -EINVAL() if ($off > $len);
453 return 0 if ($off == $len);
455 $buf_len = $len-$off if ($len - $off < $buf_len);
457 return substr($files{$file}{cont},$off,$buf_len);
461 print "transaction rollback\n";
462 $dbh->rollback || die $dbh->errstr;
463 print "invalidate all cached content\n";
464 foreach my $f (keys %files) {
465 delete $files{$f}{cont};
466 delete $files{$f}{ctime};
468 print "begin new transaction\n";
469 #$dbh->begin_work || die $dbh->errstr;
474 my $file = shift || die;
476 $files{$file}{ctime} = time();
483 if (!$sth->{'update'}->execute($cont,$id)) {
484 print "update problem: ",$sth->{'update'}->errstr;
488 if (! $dbh->commit) {
489 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
493 print "updated '$file' [",$files{$file}{id},"]\n";
495 $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
501 my $file = filename_fixup(shift);
502 my ($buffer,$off) = @_;
504 return -ENOENT() unless exists($files{$file});
506 my $cont = $files{$file}{cont};
507 my $len = length($cont);
509 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
511 $files{$file}{cont} = "";
513 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
514 $files{$file}{cont} .= $buffer;
515 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
517 $files{$file}{size} = length($files{$file}{cont});
519 if (! update_db($file)) {
522 return length($buffer);
527 my $file = filename_fixup(shift);
530 print "truncate to $size\n";
532 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
533 $files{$file}{size} = $size;
539 my ($atime,$mtime,$file) = @_;
540 $file = filename_fixup($file);
542 return -ENOENT() unless exists($files{$file});
544 print "utime '$file' $atime $mtime\n";
546 $files{$file}{time} = $mtime;
555 foreach my $f (keys %files) {
556 if ($f !~ /(^|\/)\.\.?$/) {
557 $size += $files{$f}{size} || 0;
560 print "$inodes: $f [$size]\n";
563 $size = int(($size+BLOCK-1)/BLOCK);
565 my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
567 #print "statfs: ",join(",",@ret),"\n";
573 my $file = filename_fixup(shift);
575 # if (exists( $dirs{$file} )) {
576 # print "unlink '$file' will re-read template names\n";
577 # print Dumper($fuse_self);
578 # $$fuse_self->{'read_filenames'}->();
580 if (exists( $files{$file} )) {
581 print "unlink '$file' will invalidate cache\n";
582 read_content($file,$files{$file}{id});
597 Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
598 (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
599 automagically pick it up.
603 C<FUSE (Filesystem in USErspace)> website
604 L<http://fuse.sourceforge.net/>
606 Example for WebGUI which comes with this distribution in
607 directory C<examples/webgui.pl>. It also contains a lot of documentation
608 about design of this module, usage and limitations.
612 Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
614 =head1 COPYRIGHT AND LICENSE
616 Copyright (C) 2004 by Dobrica Pavlinusic
618 This library is free software; you can redistribute it and/or modify
619 it under the same terms as Perl itself, either Perl version 5.8.4 or,
620 at your option, any later version of Perl 5 you may have available.