/[fuse_dbi]/trunk/DBI.pm
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Revision 53 - (hide annotations)
Sun Nov 28 20:20:36 2004 UTC (18 years ago) by dpavlin
File size: 13460 byte(s)
fixed work-around for non-working fusermount, removed some debugging output

1 dpavlin 1 #!/usr/bin/perl
2    
3 dpavlin 9 package Fuse::DBI;
4    
5     use 5.008;
6     use strict;
7     use warnings;
8    
9 dpavlin 7 use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
10 dpavlin 1 use Fuse;
11     use DBI;
12 dpavlin 11 use Carp;
13     use Data::Dumper;
14 dpavlin 1
15 dpavlin 47 our $VERSION = '0.07';
16 dpavlin 1
17 dpavlin 52 # block size for this filesystem
18     use constant BLOCK => 1024;
19    
20 dpavlin 9 =head1 NAME
21 dpavlin 1
22 dpavlin 9 Fuse::DBI - mount your database as filesystem and use it
23 dpavlin 1
24 dpavlin 9 =head1 SYNOPSIS
25 dpavlin 6
26 dpavlin 9 use Fuse::DBI;
27 dpavlin 11 Fuse::DBI->mount( ... );
28 dpavlin 1
29 dpavlin 28 See C<run> below for examples how to set parameters.
30 dpavlin 1
31 dpavlin 9 =head1 DESCRIPTION
32 dpavlin 1
33 dpavlin 23 This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
34 dpavlin 36 available at L<http://fuse.sourceforge.net/> to mount
35 dpavlin 9 your database as file system.
36 dpavlin 1
37 dpavlin 28 That will give you possibility to use normal file-system tools (cat, grep, vi)
38 dpavlin 9 to manipulate data in database.
39 dpavlin 1
40 dpavlin 9 It's actually opposite of Oracle's intention to put everything into database.
41 dpavlin 1
42    
43 dpavlin 9 =head1 METHODS
44    
45     =cut
46    
47 dpavlin 11 =head2 mount
48 dpavlin 9
49     Mount your database as filesystem.
50    
51 dpavlin 28 Let's suppose that your database have table C<files> with following structure:
52    
53     id: int
54     filename: text
55     size: int
56     content: text
57     writable: boolean
58    
59     Following is example how to mount table like that to C</mnt>:
60    
61 dpavlin 11 my $mnt = Fuse::DBI->mount({
62 dpavlin 28 '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 { ... },
69 dpavlin 9 });
70    
71 dpavlin 28 Options:
72    
73     =over 5
74    
75     =item filenames
76    
77     SQL query which returns C<id> (unique id for that row), C<filename>,
78     C<size> and C<writable> boolean flag.
79    
80     =item read
81    
82     SQL query which returns only one column with content of file and has
83     placeholder C<?> for C<id>.
84    
85     =item update
86    
87     SQL query with two pace-holders, one for new content and one for C<id>.
88    
89     =item dsn
90    
91     C<DBI> dsn to connect to (contains database driver and name of database).
92    
93     =item user
94    
95     User with which to connect to database
96    
97     =item password
98    
99     Password for connecting to database
100    
101     =item invalidate
102    
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>.
106    
107     =item fork
108    
109     Optional flag which forks after mount so that executing script will continue
110     running. Implementation is experimental.
111    
112     =back
113    
114 dpavlin 9 =cut
115    
116     my $dbh;
117     my $sth;
118     my $ctime_start;
119    
120 dpavlin 11 sub read_filenames;
121 dpavlin 21 sub fuse_module_loaded;
122 dpavlin 9
123 dpavlin 24 # 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
125     # be a problem.
126     my $fuse_self;
127    
128 dpavlin 11 sub mount {
129     my $class = shift;
130     my $self = {};
131     bless($self, $class);
132 dpavlin 9
133 dpavlin 11 my $arg = shift;
134 dpavlin 9
135 dpavlin 11 print Dumper($arg);
136    
137 dpavlin 51 unless ($self->fuse_module_loaded) {
138     print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n";
139     system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n";
140     }
141    
142 dpavlin 11 carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
143     carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
144    
145 dpavlin 12 # save (some) arguments in self
146 dpavlin 24 foreach (qw(mount invalidate)) {
147     $self->{$_} = $arg->{$_};
148     }
149 dpavlin 12
150 dpavlin 9 foreach (qw(filenames read update)) {
151 dpavlin 11 carp "mount needs '$_' SQL" unless ($arg->{$_});
152 dpavlin 9 }
153    
154 dpavlin 21 $ctime_start = time();
155 dpavlin 9
156 dpavlin 22 my $pid;
157 dpavlin 21 if ($arg->{'fork'}) {
158 dpavlin 22 $pid = fork();
159 dpavlin 21 die "fork() failed: $!" unless defined $pid;
160     # child will return to caller
161     if ($pid) {
162 dpavlin 47 my $counter = 4;
163     while ($counter && ! $self->is_mounted) {
164     select(undef, undef, undef, 0.5);
165     $counter--;
166     }
167     if ($self->is_mounted) {
168     return $self;
169     } else {
170     return undef;
171     }
172 dpavlin 21 }
173     }
174 dpavlin 9
175 dpavlin 21 $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
176    
177 dpavlin 26 $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
178 dpavlin 9
179     $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
180     $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
181    
182 dpavlin 26
183     $self->{'sth'} = $sth;
184    
185     $self->{'read_filenames'} = sub { $self->read_filenames };
186 dpavlin 21 $self->read_filenames;
187 dpavlin 9
188 dpavlin 26 $fuse_self = \$self;
189    
190 dpavlin 22 Fuse::main(
191 dpavlin 21 mountpoint=>$arg->{'mount'},
192     getattr=>\&e_getattr,
193     getdir=>\&e_getdir,
194     open=>\&e_open,
195     statfs=>\&e_statfs,
196     read=>\&e_read,
197     write=>\&e_write,
198     utime=>\&e_utime,
199     truncate=>\&e_truncate,
200     unlink=>\&e_unlink,
201 dpavlin 26 rmdir=>\&e_unlink,
202 dpavlin 21 debug=>0,
203     );
204 dpavlin 26
205 dpavlin 22 exit(0) if ($arg->{'fork'});
206    
207     return 1;
208    
209 dpavlin 9 };
210    
211 dpavlin 47 =head2 is_mounted
212    
213     Check if fuse filesystem is mounted
214    
215     if ($mnt->is_mounted) { ... }
216    
217     =cut
218    
219     sub is_mounted {
220     my $self = shift;
221    
222     my $mounted = 0;
223     my $mount = $self->{'mount'} || confess "can't find mount point!";
224     if (open(MTAB, "/etc/mtab")) {
225     while(<MTAB>) {
226     $mounted = 1 if (/ $mount fuse /i);
227     }
228     close(MTAB);
229     } else {
230     warn "can't open /etc/mtab: $!";
231     }
232    
233     return $mounted;
234     }
235    
236    
237 dpavlin 11 =head2 umount
238    
239     Unmount your database as filesystem.
240    
241     $mnt->umount;
242    
243     This will also kill background process which is translating
244     database to filesystem.
245    
246     =cut
247    
248     sub umount {
249     my $self = shift;
250    
251 dpavlin 47 if ($self->{'mount'} && $self->is_mounted) {
252 dpavlin 53 system "( fusermount -u ".$self->{'mount'}." 2>&1 ) >/dev/null";
253     if ($self->is_mounted) {
254 dpavlin 51 system "sudo umount ".$self->{'mount'} ||
255     return 0;
256 dpavlin 53 }
257 dpavlin 47 return 1;
258     }
259 dpavlin 40
260 dpavlin 47 return 0;
261 dpavlin 21 }
262    
263 dpavlin 26 $SIG{'INT'} = sub {
264 dpavlin 40 if ($fuse_self && $$fuse_self->umount) {
265     print STDERR "umount called by SIG INT\n";
266     }
267 dpavlin 26 };
268 dpavlin 24
269 dpavlin 40 $SIG{'QUIT'} = sub {
270     if ($fuse_self && $$fuse_self->umount) {
271     print STDERR "umount called by SIG QUIT\n";
272     }
273     };
274    
275 dpavlin 24 sub DESTROY {
276     my $self = shift;
277 dpavlin 40 if ($self->umount) {
278     print STDERR "umount called by DESTROY\n";
279     }
280 dpavlin 24 }
281    
282 dpavlin 21 =head2 fuse_module_loaded
283    
284     Checks if C<fuse> module is loaded in kernel.
285    
286     die "no fuse module loaded in kernel"
287     unless (Fuse::DBI::fuse_module_loaded);
288    
289 dpavlin 28 This function in called by C<mount>, but might be useful alone also.
290 dpavlin 21
291     =cut
292    
293     sub fuse_module_loaded {
294     my $lsmod = `lsmod`;
295     die "can't start lsmod: $!" unless ($lsmod);
296     if ($lsmod =~ m/fuse/s) {
297     return 1;
298 dpavlin 12 } else {
299 dpavlin 21 return 0;
300 dpavlin 12 }
301 dpavlin 11 }
302    
303 dpavlin 9 my %files;
304 dpavlin 1
305 dpavlin 9 sub read_filenames {
306 dpavlin 11 my $self = shift;
307    
308 dpavlin 26 my $sth = $self->{'sth'} || die "no sth argument";
309    
310 dpavlin 9 # create empty filesystem
311     (%files) = (
312     '.' => {
313     type => 0040,
314     mode => 0755,
315     },
316 dpavlin 40 '..' => {
317     type => 0040,
318     mode => 0755,
319     },
320 dpavlin 9 # a => {
321     # cont => "File 'a'.\n",
322     # type => 0100,
323     # ctime => time()-2000
324     # },
325     );
326 dpavlin 1
327 dpavlin 9 # fetch new filename list from database
328     $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
329    
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,
336     };
337    
338     my $d;
339     foreach (split(m!/!, $row->{'filename'})) {
340     # first, entry is assumed to be file
341     if ($d) {
342     $files{$d} = {
343     mode => 0755,
344     type => 0040
345     };
346     $files{$d.'/.'} = {
347     mode => 0755,
348     type => 0040
349     };
350     $files{$d.'/..'} = {
351     mode => 0755,
352     type => 0040
353     };
354     }
355     $d .= "/" if ($d);
356     $d .= "$_";
357 dpavlin 1 }
358     }
359 dpavlin 9
360 dpavlin 51 print "found ",scalar(keys %files)," files\n";
361 dpavlin 1 }
362    
363    
364     sub filename_fixup {
365     my ($file) = shift;
366     $file =~ s,^/,,;
367     $file = '.' unless length($file);
368     return $file;
369     }
370    
371     sub e_getattr {
372     my ($file) = filename_fixup(shift);
373     $file =~ s,^/,,;
374     $file = '.' unless length($file);
375     return -ENOENT() unless exists($files{$file});
376 dpavlin 52 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 dpavlin 1 my ($atime, $ctime, $mtime);
379     $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
380    
381     my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
382    
383     # 2 possible types of return values:
384     #return -ENOENT(); # or any other error you care to
385 dpavlin 53 #print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n";
386 dpavlin 1 return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
387     }
388    
389     sub e_getdir {
390     my ($dirname) = shift;
391     $dirname =~ s!^/!!;
392     # return as many text filenames as you like, followed by the retval.
393     print((scalar keys %files)." files total\n");
394     my %out;
395 dpavlin 13 foreach my $f (sort keys %files) {
396 dpavlin 1 if ($dirname) {
397 dpavlin 32 if ($f =~ s/^\Q$dirname\E\///) {
398 dpavlin 13 $out{$f}++ if ($f =~ /^[^\/]+$/);
399     }
400 dpavlin 1 } else {
401     $out{$f}++ if ($f =~ /^[^\/]+$/);
402     }
403     }
404     if (! %out) {
405     $out{'no files? bug?'}++;
406     }
407 dpavlin 8 print scalar keys %out," files in dir '$dirname'\n";
408 dpavlin 13 print "## ",join(" ",keys %out),"\n";
409 dpavlin 1 return (keys %out),0;
410     }
411    
412 dpavlin 21 sub read_content {
413     my ($file,$id) = @_;
414    
415     die "read_content needs file and id" unless ($file && $id);
416    
417     $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
418     $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
419 dpavlin 31 # I should modify ctime only if content in database changed
420     #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
421 dpavlin 21 print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
422     }
423    
424    
425 dpavlin 1 sub e_open {
426     # VFS sanity check; it keeps all the necessary state, not much to do here.
427 dpavlin 6 my $file = filename_fixup(shift);
428     my $flags = shift;
429    
430 dpavlin 1 return -ENOENT() unless exists($files{$file});
431     return -EISDIR() unless exists($files{$file}{id});
432 dpavlin 6
433 dpavlin 21 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
434    
435 dpavlin 3 print "open '$file' ",length($files{$file}{cont})," bytes\n";
436 dpavlin 1 return 0;
437     }
438    
439     sub e_read {
440 dpavlin 3 # return an error numeric, or binary/text string.
441     # (note: 0 means EOF, "0" will give a byte (ascii "0")
442     # to the reading program)
443 dpavlin 1 my ($file) = filename_fixup(shift);
444 dpavlin 8 my ($buf_len,$off) = @_;
445 dpavlin 3
446 dpavlin 1 return -ENOENT() unless exists($files{$file});
447 dpavlin 3
448     my $len = length($files{$file}{cont});
449    
450 dpavlin 8 print "read '$file' [$len bytes] offset $off length $buf_len\n";
451 dpavlin 3
452     return -EINVAL() if ($off > $len);
453     return 0 if ($off == $len);
454    
455 dpavlin 21 $buf_len = $len-$off if ($len - $off < $buf_len);
456 dpavlin 3
457 dpavlin 8 return substr($files{$file}{cont},$off,$buf_len);
458 dpavlin 1 }
459    
460 dpavlin 6 sub clear_cont {
461 dpavlin 7 print "transaction rollback\n";
462     $dbh->rollback || die $dbh->errstr;
463 dpavlin 6 print "invalidate all cached content\n";
464     foreach my $f (keys %files) {
465     delete $files{$f}{cont};
466 dpavlin 31 delete $files{$f}{ctime};
467 dpavlin 6 }
468 dpavlin 7 print "begin new transaction\n";
469 dpavlin 21 #$dbh->begin_work || die $dbh->errstr;
470 dpavlin 6 }
471    
472    
473     sub update_db {
474     my $file = shift || die;
475    
476 dpavlin 8 $files{$file}{ctime} = time();
477    
478 dpavlin 21 my ($cont,$id) = (
479     $files{$file}{cont},
480     $files{$file}{id}
481     );
482    
483     if (!$sth->{'update'}->execute($cont,$id)) {
484 dpavlin 9 print "update problem: ",$sth->{'update'}->errstr;
485 dpavlin 6 clear_cont;
486     return 0;
487     } else {
488 dpavlin 7 if (! $dbh->commit) {
489 dpavlin 9 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
490 dpavlin 6 clear_cont;
491     return 0;
492     }
493     print "updated '$file' [",$files{$file}{id},"]\n";
494 dpavlin 24
495 dpavlin 26 $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
496 dpavlin 6 }
497     return 1;
498     }
499    
500     sub e_write {
501     my $file = filename_fixup(shift);
502 dpavlin 18 my ($buffer,$off) = @_;
503 dpavlin 6
504     return -ENOENT() unless exists($files{$file});
505    
506 dpavlin 18 my $cont = $files{$file}{cont};
507     my $len = length($cont);
508 dpavlin 6
509 dpavlin 18 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
510 dpavlin 6
511 dpavlin 18 $files{$file}{cont} = "";
512 dpavlin 6
513 dpavlin 18 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
514     $files{$file}{cont} .= $buffer;
515 dpavlin 21 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
516 dpavlin 18
517     $files{$file}{size} = length($files{$file}{cont});
518    
519 dpavlin 6 if (! update_db($file)) {
520     return -ENOSYS();
521     } else {
522 dpavlin 18 return length($buffer);
523 dpavlin 6 }
524     }
525    
526     sub e_truncate {
527     my $file = filename_fixup(shift);
528     my $size = shift;
529    
530 dpavlin 18 print "truncate to $size\n";
531    
532 dpavlin 6 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
533 dpavlin 18 $files{$file}{size} = $size;
534 dpavlin 6 return 0
535     };
536    
537    
538     sub e_utime {
539     my ($atime,$mtime,$file) = @_;
540     $file = filename_fixup($file);
541    
542     return -ENOENT() unless exists($files{$file});
543    
544 dpavlin 8 print "utime '$file' $atime $mtime\n";
545    
546 dpavlin 6 $files{$file}{time} = $mtime;
547     return 0;
548     }
549    
550 dpavlin 51 sub e_statfs {
551 dpavlin 1
552 dpavlin 51 my $size = 0;
553     my $inodes = 0;
554    
555     foreach my $f (keys %files) {
556     if ($f !~ /(^|\/)\.\.?$/) {
557     $size += $files{$f}{size} || 0;
558     $inodes++;
559     }
560     print "$inodes: $f [$size]\n";
561     }
562    
563 dpavlin 52 $size = int(($size+BLOCK-1)/BLOCK);
564 dpavlin 51
565 dpavlin 52 my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
566 dpavlin 51
567 dpavlin 53 #print "statfs: ",join(",",@ret),"\n";
568 dpavlin 51
569     return @ret;
570     }
571    
572 dpavlin 21 sub e_unlink {
573     my $file = filename_fixup(shift);
574    
575 dpavlin 51 # if (exists( $dirs{$file} )) {
576     # print "unlink '$file' will re-read template names\n";
577     # print Dumper($fuse_self);
578     # $$fuse_self->{'read_filenames'}->();
579     # return 0;
580     if (exists( $files{$file} )) {
581 dpavlin 26 print "unlink '$file' will invalidate cache\n";
582     read_content($file,$files{$file}{id});
583     return 0;
584     }
585 dpavlin 21
586 dpavlin 26 return -ENOENT();
587 dpavlin 21 }
588 dpavlin 9 1;
589     __END__
590    
591     =head1 EXPORT
592    
593     Nothing.
594    
595 dpavlin 40 =head1 BUGS
596    
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.
600    
601 dpavlin 9 =head1 SEE ALSO
602    
603     C<FUSE (Filesystem in USErspace)> website
604 dpavlin 36 L<http://fuse.sourceforge.net/>
605 dpavlin 9
606 dpavlin 28 Example for WebGUI which comes with this distribution in
607 dpavlin 30 directory C<examples/webgui.pl>. It also contains a lot of documentation
608 dpavlin 28 about design of this module, usage and limitations.
609    
610 dpavlin 9 =head1 AUTHOR
611    
612     Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
613    
614     =head1 COPYRIGHT AND LICENSE
615    
616     Copyright (C) 2004 by Dobrica Pavlinusic
617    
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.
621    
622    
623     =cut
624    

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