/[fuse_dbi]/trunk/DBI.pm
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Revision 22 - (hide annotations)
Sat Oct 2 16:30:16 2004 UTC (18 years, 4 months ago) by dpavlin
File size: 9444 byte(s)
fixed fork option and tests

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 11
16 dpavlin 21 our $VERSION = '0.03';
17 dpavlin 1
18 dpavlin 9 =head1 NAME
19 dpavlin 1
20 dpavlin 9 Fuse::DBI - mount your database as filesystem and use it
21 dpavlin 1
22 dpavlin 9 =head1 SYNOPSIS
23 dpavlin 6
24 dpavlin 9 use Fuse::DBI;
25 dpavlin 11 Fuse::DBI->mount( ... );
26 dpavlin 1
27 dpavlin 9 See L<run> below for examples how to set parametars.
28 dpavlin 1
29 dpavlin 9 =head1 DESCRIPTION
30 dpavlin 1
31 dpavlin 9 This module will use L<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.
34 dpavlin 1
35 dpavlin 9 That will give you posibility to use normal file-system tools (cat, grep, vi)
36     to manipulate data in database.
37 dpavlin 1
38 dpavlin 9 It's actually opposite of Oracle's intention to put everything into database.
39 dpavlin 1
40    
41 dpavlin 9 =head1 METHODS
42    
43     =cut
44    
45 dpavlin 11 =head2 mount
46 dpavlin 9
47     Mount your database as filesystem.
48    
49 dpavlin 11 my $mnt = Fuse::DBI->mount({
50 dpavlin 21 filenames => 'select name from files_table as filenames',
51 dpavlin 9 read => 'sql read',
52     update => 'sql update',
53     dsn => 'DBI:Pg:dbname=webgui',
54     user => 'database_user',
55     password => 'database_password'
56     });
57    
58     =cut
59    
60     my $dbh;
61     my $sth;
62     my $ctime_start;
63    
64 dpavlin 11 sub read_filenames;
65 dpavlin 21 sub fuse_module_loaded;
66 dpavlin 9
67 dpavlin 11 sub mount {
68     my $class = shift;
69     my $self = {};
70     bless($self, $class);
71 dpavlin 9
72 dpavlin 11 my $arg = shift;
73 dpavlin 9
74 dpavlin 11 print Dumper($arg);
75    
76     carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
77     carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
78    
79 dpavlin 12 # save (some) arguments in self
80     $self->{$_} = $arg->{$_} foreach (qw(mount));
81    
82 dpavlin 9 foreach (qw(filenames read update)) {
83 dpavlin 11 carp "mount needs '$_' SQL" unless ($arg->{$_});
84 dpavlin 9 }
85    
86 dpavlin 21 $ctime_start = time();
87 dpavlin 9
88 dpavlin 22 my $pid;
89 dpavlin 21 if ($arg->{'fork'}) {
90 dpavlin 22 $pid = fork();
91 dpavlin 21 die "fork() failed: $!" unless defined $pid;
92     # child will return to caller
93     if ($pid) {
94 dpavlin 22 return $self;
95 dpavlin 21 }
96     }
97 dpavlin 9
98 dpavlin 21 $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
99    
100 dpavlin 9 $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
101    
102     $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
103     $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
104    
105 dpavlin 21 $self->read_filenames;
106 dpavlin 9
107 dpavlin 22 Fuse::main(
108 dpavlin 21 mountpoint=>$arg->{'mount'},
109     getattr=>\&e_getattr,
110     getdir=>\&e_getdir,
111     open=>\&e_open,
112     statfs=>\&e_statfs,
113     read=>\&e_read,
114     write=>\&e_write,
115     utime=>\&e_utime,
116     truncate=>\&e_truncate,
117     unlink=>\&e_unlink,
118     debug=>0,
119     );
120 dpavlin 9
121 dpavlin 22 exit(0) if ($arg->{'fork'});
122    
123     return 1;
124    
125 dpavlin 9 };
126    
127 dpavlin 11 =head2 umount
128    
129     Unmount your database as filesystem.
130    
131     $mnt->umount;
132    
133     This will also kill background process which is translating
134     database to filesystem.
135    
136     =cut
137    
138     sub umount {
139     my $self = shift;
140    
141 dpavlin 12 system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
142    
143 dpavlin 21 return 1;
144     }
145    
146     =head2 fuse_module_loaded
147    
148     Checks if C<fuse> module is loaded in kernel.
149    
150     die "no fuse module loaded in kernel"
151     unless (Fuse::DBI::fuse_module_loaded);
152    
153     This function in called by L<mount>, but might be useful alone also.
154    
155     =cut
156    
157     sub fuse_module_loaded {
158     my $lsmod = `lsmod`;
159     die "can't start lsmod: $!" unless ($lsmod);
160     if ($lsmod =~ m/fuse/s) {
161     return 1;
162 dpavlin 12 } else {
163 dpavlin 21 return 0;
164 dpavlin 12 }
165 dpavlin 11 }
166    
167 dpavlin 9 my %files;
168 dpavlin 1 my %dirs;
169    
170 dpavlin 9 sub read_filenames {
171 dpavlin 11 my $self = shift;
172    
173 dpavlin 9 # create empty filesystem
174     (%files) = (
175     '.' => {
176     type => 0040,
177     mode => 0755,
178     },
179     # a => {
180     # cont => "File 'a'.\n",
181     # type => 0100,
182     # ctime => time()-2000
183     # },
184     );
185 dpavlin 1
186 dpavlin 9 # fetch new filename list from database
187     $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
188    
189     # read them in with sesible defaults
190     while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
191     $files{$row->{'filename'}} = {
192     size => $row->{'size'},
193     mode => $row->{'writable'} ? 0644 : 0444,
194     id => $row->{'id'} || 99,
195     };
196    
197     my $d;
198     foreach (split(m!/!, $row->{'filename'})) {
199     # first, entry is assumed to be file
200     if ($d) {
201     $files{$d} = {
202     size => $dirs{$d}++,
203     mode => 0755,
204     type => 0040
205     };
206     $files{$d.'/.'} = {
207     mode => 0755,
208     type => 0040
209     };
210     $files{$d.'/..'} = {
211     mode => 0755,
212     type => 0040
213     };
214     }
215     $d .= "/" if ($d);
216     $d .= "$_";
217 dpavlin 1 }
218     }
219 dpavlin 9
220     print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
221 dpavlin 1 }
222    
223    
224     sub filename_fixup {
225     my ($file) = shift;
226     $file =~ s,^/,,;
227     $file = '.' unless length($file);
228     return $file;
229     }
230    
231     sub e_getattr {
232     my ($file) = filename_fixup(shift);
233     $file =~ s,^/,,;
234     $file = '.' unless length($file);
235     return -ENOENT() unless exists($files{$file});
236     my ($size) = $files{$file}{size} || 1;
237     my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);
238     my ($atime, $ctime, $mtime);
239     $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
240    
241     my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
242    
243     # 2 possible types of return values:
244     #return -ENOENT(); # or any other error you care to
245     #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n");
246     return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
247     }
248    
249     sub e_getdir {
250     my ($dirname) = shift;
251     $dirname =~ s!^/!!;
252     # return as many text filenames as you like, followed by the retval.
253     print((scalar keys %files)." files total\n");
254     my %out;
255 dpavlin 13 foreach my $f (sort keys %files) {
256 dpavlin 1 if ($dirname) {
257 dpavlin 13 if ($f =~ s/^\E$dirname\Q\///) {
258     $out{$f}++ if ($f =~ /^[^\/]+$/);
259     }
260 dpavlin 1 } else {
261     $out{$f}++ if ($f =~ /^[^\/]+$/);
262     }
263     }
264     if (! %out) {
265     $out{'no files? bug?'}++;
266     }
267 dpavlin 8 print scalar keys %out," files in dir '$dirname'\n";
268 dpavlin 13 print "## ",join(" ",keys %out),"\n";
269 dpavlin 1 return (keys %out),0;
270     }
271    
272 dpavlin 21 sub read_content {
273     my ($file,$id) = @_;
274    
275     die "read_content needs file and id" unless ($file && $id);
276    
277     $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
278     $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
279     print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
280     }
281    
282    
283 dpavlin 1 sub e_open {
284     # VFS sanity check; it keeps all the necessary state, not much to do here.
285 dpavlin 6 my $file = filename_fixup(shift);
286     my $flags = shift;
287    
288 dpavlin 1 return -ENOENT() unless exists($files{$file});
289     return -EISDIR() unless exists($files{$file}{id});
290 dpavlin 6
291 dpavlin 21 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
292    
293 dpavlin 3 print "open '$file' ",length($files{$file}{cont})," bytes\n";
294 dpavlin 1 return 0;
295     }
296    
297     sub e_read {
298 dpavlin 3 # return an error numeric, or binary/text string.
299     # (note: 0 means EOF, "0" will give a byte (ascii "0")
300     # to the reading program)
301 dpavlin 1 my ($file) = filename_fixup(shift);
302 dpavlin 8 my ($buf_len,$off) = @_;
303 dpavlin 3
304 dpavlin 1 return -ENOENT() unless exists($files{$file});
305 dpavlin 3
306     my $len = length($files{$file}{cont});
307    
308 dpavlin 8 print "read '$file' [$len bytes] offset $off length $buf_len\n";
309 dpavlin 3
310     return -EINVAL() if ($off > $len);
311     return 0 if ($off == $len);
312    
313 dpavlin 21 $buf_len = $len-$off if ($len - $off < $buf_len);
314 dpavlin 3
315 dpavlin 8 return substr($files{$file}{cont},$off,$buf_len);
316 dpavlin 1 }
317    
318 dpavlin 6 sub clear_cont {
319 dpavlin 7 print "transaction rollback\n";
320     $dbh->rollback || die $dbh->errstr;
321 dpavlin 6 print "invalidate all cached content\n";
322     foreach my $f (keys %files) {
323     delete $files{$f}{cont};
324     }
325 dpavlin 7 print "begin new transaction\n";
326 dpavlin 21 #$dbh->begin_work || die $dbh->errstr;
327 dpavlin 6 }
328    
329    
330     sub update_db {
331     my $file = shift || die;
332    
333 dpavlin 8 $files{$file}{ctime} = time();
334    
335 dpavlin 21 my ($cont,$id) = (
336     $files{$file}{cont},
337     $files{$file}{id}
338     );
339    
340     if (!$sth->{'update'}->execute($cont,$id)) {
341 dpavlin 9 print "update problem: ",$sth->{'update'}->errstr;
342 dpavlin 6 clear_cont;
343     return 0;
344     } else {
345 dpavlin 7 if (! $dbh->commit) {
346 dpavlin 9 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
347 dpavlin 6 clear_cont;
348     return 0;
349     }
350     print "updated '$file' [",$files{$file}{id},"]\n";
351     }
352     return 1;
353     }
354    
355     sub e_write {
356     my $file = filename_fixup(shift);
357 dpavlin 18 my ($buffer,$off) = @_;
358 dpavlin 6
359     return -ENOENT() unless exists($files{$file});
360    
361 dpavlin 18 my $cont = $files{$file}{cont};
362     my $len = length($cont);
363 dpavlin 6
364 dpavlin 18 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
365 dpavlin 6
366 dpavlin 18 $files{$file}{cont} = "";
367 dpavlin 6
368 dpavlin 18 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
369     $files{$file}{cont} .= $buffer;
370 dpavlin 21 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
371 dpavlin 18
372     $files{$file}{size} = length($files{$file}{cont});
373    
374 dpavlin 6 if (! update_db($file)) {
375     return -ENOSYS();
376     } else {
377 dpavlin 18 return length($buffer);
378 dpavlin 6 }
379     }
380    
381     sub e_truncate {
382     my $file = filename_fixup(shift);
383     my $size = shift;
384    
385 dpavlin 18 print "truncate to $size\n";
386    
387 dpavlin 6 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
388 dpavlin 18 $files{$file}{size} = $size;
389 dpavlin 6 return 0
390     };
391    
392    
393     sub e_utime {
394     my ($atime,$mtime,$file) = @_;
395     $file = filename_fixup($file);
396    
397     return -ENOENT() unless exists($files{$file});
398    
399 dpavlin 8 print "utime '$file' $atime $mtime\n";
400    
401 dpavlin 6 $files{$file}{time} = $mtime;
402     return 0;
403     }
404    
405 dpavlin 1 sub e_statfs { return 255, 1, 1, 1, 1, 2 }
406    
407 dpavlin 21 sub e_unlink {
408     my $file = filename_fixup(shift);
409    
410     return -ENOENT() unless exists($files{$file});
411    
412     print "unlink '$file' will invalidate cache\n";
413    
414     read_content($file,$files{$file}{id});
415    
416     return 0;
417     }
418 dpavlin 9 1;
419     __END__
420    
421     =head1 EXPORT
422    
423     Nothing.
424    
425     =head1 SEE ALSO
426    
427     C<FUSE (Filesystem in USErspace)> website
428     L<http://sourceforge.net/projects/avf>
429    
430     =head1 AUTHOR
431    
432     Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
433    
434     =head1 COPYRIGHT AND LICENSE
435    
436     Copyright (C) 2004 by Dobrica Pavlinusic
437    
438     This library is free software; you can redistribute it and/or modify
439     it under the same terms as Perl itself, either Perl version 5.8.4 or,
440     at your option, any later version of Perl 5 you may have available.
441    
442    
443     =cut
444    

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