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 system "sudo umount ".$self->{'mount'} ||
262 if ($fuse_self && $$fuse_self->umount) {
263 print STDERR "umount called by SIG INT\n";
268 if ($fuse_self && $$fuse_self->umount) {
269 print STDERR "umount called by SIG QUIT\n";
276 print STDERR "umount called by DESTROY\n";
280 =head2 fuse_module_loaded
282 Checks if C<fuse> module is loaded in kernel.
284 die "no fuse module loaded in kernel"
285 unless (Fuse::DBI::fuse_module_loaded);
287 This function in called by C<mount>, but might be useful alone also.
291 sub fuse_module_loaded {
293 die "can't start lsmod: $!" unless ($lsmod);
294 if ($lsmod =~ m/fuse/s) {
306 my $sth = $self->{'sth'} || die "no sth argument";
308 # create empty filesystem
319 # cont => "File 'a'.\n",
321 # ctime => time()-2000
325 # fetch new filename list from database
326 $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
328 # read them in with sesible defaults
329 while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
330 $files{$row->{'filename'}} = {
331 size => $row->{'size'},
332 mode => $row->{'writable'} ? 0644 : 0444,
333 id => $row->{'id'} || 99,
337 foreach (split(m!/!, $row->{'filename'})) {
338 # first, entry is assumed to be file
358 print "found ",scalar(keys %files)," files\n";
365 $file = '.' unless length($file);
370 my ($file) = filename_fixup(shift);
372 $file = '.' unless length($file);
373 return -ENOENT() unless exists($files{$file});
374 my ($size) = $files{$file}{size} || BLOCK;
375 my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+BLOCK-1)/BLOCK),0,0,1,BLOCK);
376 my ($atime, $ctime, $mtime);
377 $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
379 my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
381 # 2 possible types of return values:
382 #return -ENOENT(); # or any other error you care to
383 print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n";
384 return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
388 my ($dirname) = shift;
390 # return as many text filenames as you like, followed by the retval.
391 print((scalar keys %files)." files total\n");
393 foreach my $f (sort keys %files) {
395 if ($f =~ s/^\Q$dirname\E\///) {
396 $out{$f}++ if ($f =~ /^[^\/]+$/);
399 $out{$f}++ if ($f =~ /^[^\/]+$/);
403 $out{'no files? bug?'}++;
405 print scalar keys %out," files in dir '$dirname'\n";
406 print "## ",join(" ",keys %out),"\n";
407 return (keys %out),0;
413 die "read_content needs file and id" unless ($file && $id);
415 $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
416 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
417 # I should modify ctime only if content in database changed
418 #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
419 print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
424 # VFS sanity check; it keeps all the necessary state, not much to do here.
425 my $file = filename_fixup(shift);
428 return -ENOENT() unless exists($files{$file});
429 return -EISDIR() unless exists($files{$file}{id});
431 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
433 print "open '$file' ",length($files{$file}{cont})," bytes\n";
438 # return an error numeric, or binary/text string.
439 # (note: 0 means EOF, "0" will give a byte (ascii "0")
440 # to the reading program)
441 my ($file) = filename_fixup(shift);
442 my ($buf_len,$off) = @_;
444 return -ENOENT() unless exists($files{$file});
446 my $len = length($files{$file}{cont});
448 print "read '$file' [$len bytes] offset $off length $buf_len\n";
450 return -EINVAL() if ($off > $len);
451 return 0 if ($off == $len);
453 $buf_len = $len-$off if ($len - $off < $buf_len);
455 return substr($files{$file}{cont},$off,$buf_len);
459 print "transaction rollback\n";
460 $dbh->rollback || die $dbh->errstr;
461 print "invalidate all cached content\n";
462 foreach my $f (keys %files) {
463 delete $files{$f}{cont};
464 delete $files{$f}{ctime};
466 print "begin new transaction\n";
467 #$dbh->begin_work || die $dbh->errstr;
472 my $file = shift || die;
474 $files{$file}{ctime} = time();
481 if (!$sth->{'update'}->execute($cont,$id)) {
482 print "update problem: ",$sth->{'update'}->errstr;
486 if (! $dbh->commit) {
487 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
491 print "updated '$file' [",$files{$file}{id},"]\n";
493 $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
499 my $file = filename_fixup(shift);
500 my ($buffer,$off) = @_;
502 return -ENOENT() unless exists($files{$file});
504 my $cont = $files{$file}{cont};
505 my $len = length($cont);
507 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
509 $files{$file}{cont} = "";
511 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
512 $files{$file}{cont} .= $buffer;
513 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
515 $files{$file}{size} = length($files{$file}{cont});
517 if (! update_db($file)) {
520 return length($buffer);
525 my $file = filename_fixup(shift);
528 print "truncate to $size\n";
530 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
531 $files{$file}{size} = $size;
537 my ($atime,$mtime,$file) = @_;
538 $file = filename_fixup($file);
540 return -ENOENT() unless exists($files{$file});
542 print "utime '$file' $atime $mtime\n";
544 $files{$file}{time} = $mtime;
553 foreach my $f (keys %files) {
554 if ($f !~ /(^|\/)\.\.?$/) {
555 $size += $files{$f}{size} || 0;
558 print "$inodes: $f [$size]\n";
561 $size = int(($size+BLOCK-1)/BLOCK);
563 my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
565 print "statfs: ",join(",",@ret),"\n";
571 my $file = filename_fixup(shift);
573 # if (exists( $dirs{$file} )) {
574 # print "unlink '$file' will re-read template names\n";
575 # print Dumper($fuse_self);
576 # $$fuse_self->{'read_filenames'}->();
578 if (exists( $files{$file} )) {
579 print "unlink '$file' will invalidate cache\n";
580 read_content($file,$files{$file}{id});
595 Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
596 (for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
597 automagically pick it up.
601 C<FUSE (Filesystem in USErspace)> website
602 L<http://fuse.sourceforge.net/>
604 Example for WebGUI which comes with this distribution in
605 directory C<examples/webgui.pl>. It also contains a lot of documentation
606 about design of this module, usage and limitations.
610 Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
612 =head1 COPYRIGHT AND LICENSE
614 Copyright (C) 2004 by Dobrica Pavlinusic
616 This library is free software; you can redistribute it and/or modify
617 it under the same terms as Perl itself, either Perl version 5.8.4 or,
618 at your option, any later version of Perl 5 you may have available.