/[fuse_dbi]/trunk/DBI.pm
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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Contents of /trunk/DBI.pm

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Revision 24 - (show annotations)
Fri Oct 8 20:07:12 2004 UTC (19 years, 9 months ago) by dpavlin
File size: 9933 byte(s)
call umount on DESTROY, support for optional 'invalidate' code ref which
erase templates from disk (user running fuse must have permissions on
template directory for this to work)

1 #!/usr/bin/perl
2
3 package Fuse::DBI;
4
5 use 5.008;
6 use strict;
7 use warnings;
8
9 use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
10 use Fuse;
11 use DBI;
12 use Carp;
13 use Data::Dumper;
14
15
16 our $VERSION = '0.03';
17
18 =head1 NAME
19
20 Fuse::DBI - mount your database as filesystem and use it
21
22 =head1 SYNOPSIS
23
24 use Fuse::DBI;
25 Fuse::DBI->mount( ... );
26
27 See C<run> below for examples how to set parametars.
28
29 =head1 DESCRIPTION
30
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.
34
35 That will give you posibility to use normal file-system tools (cat, grep, vi)
36 to manipulate data in database.
37
38 It's actually opposite of Oracle's intention to put everything into database.
39
40
41 =head1 METHODS
42
43 =cut
44
45 =head2 mount
46
47 Mount your database as filesystem.
48
49 my $mnt = Fuse::DBI->mount({
50 filenames => 'select name from files_table as filenames',
51 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 sub read_filenames;
65 sub fuse_module_loaded;
66
67 # evil, evil way to solve this. It makes this module non-reentrant. But, since
68 # fuse calls another copy of this script for each mount anyway, this shouldn't
69 # be a problem.
70 my $fuse_self;
71
72 sub mount {
73 my $class = shift;
74 my $self = {};
75 bless($self, $class);
76
77 my $arg = shift;
78
79 print Dumper($arg);
80
81 carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
82 carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
83
84 # save (some) arguments in self
85 foreach (qw(mount invalidate)) {
86 $self->{$_} = $arg->{$_};
87 $fuse_self->{$_} = $arg->{$_};
88 }
89
90 foreach (qw(filenames read update)) {
91 carp "mount needs '$_' SQL" unless ($arg->{$_});
92 }
93
94 $ctime_start = time();
95
96 my $pid;
97 if ($arg->{'fork'}) {
98 $pid = fork();
99 die "fork() failed: $!" unless defined $pid;
100 # child will return to caller
101 if ($pid) {
102 return $self;
103 }
104 }
105
106 $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
107
108 $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
109
110 $sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
111 $sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
112
113 $self->read_filenames;
114
115 Fuse::main(
116 mountpoint=>$arg->{'mount'},
117 getattr=>\&e_getattr,
118 getdir=>\&e_getdir,
119 open=>\&e_open,
120 statfs=>\&e_statfs,
121 read=>\&e_read,
122 write=>\&e_write,
123 utime=>\&e_utime,
124 truncate=>\&e_truncate,
125 unlink=>\&e_unlink,
126 debug=>0,
127 );
128
129 exit(0) if ($arg->{'fork'});
130
131 return 1;
132
133 };
134
135 =head2 umount
136
137 Unmount your database as filesystem.
138
139 $mnt->umount;
140
141 This will also kill background process which is translating
142 database to filesystem.
143
144 =cut
145
146 sub umount {
147 my $self = shift;
148
149 system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
150
151 return 1;
152 }
153
154 #$SIG{'INT'} = sub {
155 # print STDERR "umount called by SIG INT\n";
156 # umount;
157 #};
158
159 sub DESTROY {
160 my $self = shift;
161 print STDERR "umount called by DESTROY\n";
162 $self->umount;
163 }
164
165 =head2 fuse_module_loaded
166
167 Checks if C<fuse> module is loaded in kernel.
168
169 die "no fuse module loaded in kernel"
170 unless (Fuse::DBI::fuse_module_loaded);
171
172 This function in called by L<mount>, but might be useful alone also.
173
174 =cut
175
176 sub fuse_module_loaded {
177 my $lsmod = `lsmod`;
178 die "can't start lsmod: $!" unless ($lsmod);
179 if ($lsmod =~ m/fuse/s) {
180 return 1;
181 } else {
182 return 0;
183 }
184 }
185
186 my %files;
187 my %dirs;
188
189 sub read_filenames {
190 my $self = shift;
191
192 # create empty filesystem
193 (%files) = (
194 '.' => {
195 type => 0040,
196 mode => 0755,
197 },
198 # a => {
199 # cont => "File 'a'.\n",
200 # type => 0100,
201 # ctime => time()-2000
202 # },
203 );
204
205 # fetch new filename list from database
206 $sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
207
208 # read them in with sesible defaults
209 while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
210 $files{$row->{'filename'}} = {
211 size => $row->{'size'},
212 mode => $row->{'writable'} ? 0644 : 0444,
213 id => $row->{'id'} || 99,
214 };
215
216 my $d;
217 foreach (split(m!/!, $row->{'filename'})) {
218 # first, entry is assumed to be file
219 if ($d) {
220 $files{$d} = {
221 size => $dirs{$d}++,
222 mode => 0755,
223 type => 0040
224 };
225 $files{$d.'/.'} = {
226 mode => 0755,
227 type => 0040
228 };
229 $files{$d.'/..'} = {
230 mode => 0755,
231 type => 0040
232 };
233 }
234 $d .= "/" if ($d);
235 $d .= "$_";
236 }
237 }
238
239 print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
240 }
241
242
243 sub filename_fixup {
244 my ($file) = shift;
245 $file =~ s,^/,,;
246 $file = '.' unless length($file);
247 return $file;
248 }
249
250 sub e_getattr {
251 my ($file) = filename_fixup(shift);
252 $file =~ s,^/,,;
253 $file = '.' unless length($file);
254 return -ENOENT() unless exists($files{$file});
255 my ($size) = $files{$file}{size} || 1;
256 my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);
257 my ($atime, $ctime, $mtime);
258 $atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
259
260 my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
261
262 # 2 possible types of return values:
263 #return -ENOENT(); # or any other error you care to
264 #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n");
265 return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
266 }
267
268 sub e_getdir {
269 my ($dirname) = shift;
270 $dirname =~ s!^/!!;
271 # return as many text filenames as you like, followed by the retval.
272 print((scalar keys %files)." files total\n");
273 my %out;
274 foreach my $f (sort keys %files) {
275 if ($dirname) {
276 if ($f =~ s/^\E$dirname\Q\///) {
277 $out{$f}++ if ($f =~ /^[^\/]+$/);
278 }
279 } else {
280 $out{$f}++ if ($f =~ /^[^\/]+$/);
281 }
282 }
283 if (! %out) {
284 $out{'no files? bug?'}++;
285 }
286 print scalar keys %out," files in dir '$dirname'\n";
287 print "## ",join(" ",keys %out),"\n";
288 return (keys %out),0;
289 }
290
291 sub read_content {
292 my ($file,$id) = @_;
293
294 die "read_content needs file and id" unless ($file && $id);
295
296 $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
297 $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
298 print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
299 }
300
301
302 sub e_open {
303 # VFS sanity check; it keeps all the necessary state, not much to do here.
304 my $file = filename_fixup(shift);
305 my $flags = shift;
306
307 return -ENOENT() unless exists($files{$file});
308 return -EISDIR() unless exists($files{$file}{id});
309
310 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
311
312 print "open '$file' ",length($files{$file}{cont})," bytes\n";
313 return 0;
314 }
315
316 sub e_read {
317 # return an error numeric, or binary/text string.
318 # (note: 0 means EOF, "0" will give a byte (ascii "0")
319 # to the reading program)
320 my ($file) = filename_fixup(shift);
321 my ($buf_len,$off) = @_;
322
323 return -ENOENT() unless exists($files{$file});
324
325 my $len = length($files{$file}{cont});
326
327 print "read '$file' [$len bytes] offset $off length $buf_len\n";
328
329 return -EINVAL() if ($off > $len);
330 return 0 if ($off == $len);
331
332 $buf_len = $len-$off if ($len - $off < $buf_len);
333
334 return substr($files{$file}{cont},$off,$buf_len);
335 }
336
337 sub clear_cont {
338 print "transaction rollback\n";
339 $dbh->rollback || die $dbh->errstr;
340 print "invalidate all cached content\n";
341 foreach my $f (keys %files) {
342 delete $files{$f}{cont};
343 }
344 print "begin new transaction\n";
345 #$dbh->begin_work || die $dbh->errstr;
346 }
347
348
349 sub update_db {
350 my $file = shift || die;
351
352 $files{$file}{ctime} = time();
353
354 my ($cont,$id) = (
355 $files{$file}{cont},
356 $files{$file}{id}
357 );
358
359 if (!$sth->{'update'}->execute($cont,$id)) {
360 print "update problem: ",$sth->{'update'}->errstr;
361 clear_cont;
362 return 0;
363 } else {
364 if (! $dbh->commit) {
365 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
366 clear_cont;
367 return 0;
368 }
369 print "updated '$file' [",$files{$file}{id},"]\n";
370
371 $fuse_self->{'invalidate'}->() if (ref $fuse_self->{'invalidate'});
372 }
373 return 1;
374 }
375
376 sub e_write {
377 my $file = filename_fixup(shift);
378 my ($buffer,$off) = @_;
379
380 return -ENOENT() unless exists($files{$file});
381
382 my $cont = $files{$file}{cont};
383 my $len = length($cont);
384
385 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
386
387 $files{$file}{cont} = "";
388
389 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
390 $files{$file}{cont} .= $buffer;
391 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
392
393 $files{$file}{size} = length($files{$file}{cont});
394
395 if (! update_db($file)) {
396 return -ENOSYS();
397 } else {
398 return length($buffer);
399 }
400 }
401
402 sub e_truncate {
403 my $file = filename_fixup(shift);
404 my $size = shift;
405
406 print "truncate to $size\n";
407
408 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
409 $files{$file}{size} = $size;
410 return 0
411 };
412
413
414 sub e_utime {
415 my ($atime,$mtime,$file) = @_;
416 $file = filename_fixup($file);
417
418 return -ENOENT() unless exists($files{$file});
419
420 print "utime '$file' $atime $mtime\n";
421
422 $files{$file}{time} = $mtime;
423 return 0;
424 }
425
426 sub e_statfs { return 255, 1, 1, 1, 1, 2 }
427
428 sub e_unlink {
429 my $file = filename_fixup(shift);
430
431 return -ENOENT() unless exists($files{$file});
432
433 print "unlink '$file' will invalidate cache\n";
434
435 read_content($file,$files{$file}{id});
436
437 return 0;
438 }
439 1;
440 __END__
441
442 =head1 EXPORT
443
444 Nothing.
445
446 =head1 SEE ALSO
447
448 C<FUSE (Filesystem in USErspace)> website
449 L<http://sourceforge.net/projects/avf>
450
451 =head1 AUTHOR
452
453 Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt>
454
455 =head1 COPYRIGHT AND LICENSE
456
457 Copyright (C) 2004 by Dobrica Pavlinusic
458
459 This library is free software; you can redistribute it and/or modify
460 it under the same terms as Perl itself, either Perl version 5.8.4 or,
461 at your option, any later version of Perl 5 you may have available.
462
463
464 =cut
465

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