/[fuse_dbi]/trunk/DBI.pm
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Revision 22 - (show annotations)
Sat Oct 2 16:30:16 2004 UTC (18 years, 1 month ago) by dpavlin
File size: 9444 byte(s)
fixed fork option and tests

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 L<run> below for examples how to set parametars.
28
29 =head1 DESCRIPTION
30
31 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
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 sub mount {
68 my $class = shift;
69 my $self = {};
70 bless($self, $class);
71
72 my $arg = shift;
73
74 print Dumper($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 # save (some) arguments in self
80 $self->{$_} = $arg->{$_} foreach (qw(mount));
81
82 foreach (qw(filenames read update)) {
83 carp "mount needs '$_' SQL" unless ($arg->{$_});
84 }
85
86 $ctime_start = time();
87
88 my $pid;
89 if ($arg->{'fork'}) {
90 $pid = fork();
91 die "fork() failed: $!" unless defined $pid;
92 # child will return to caller
93 if ($pid) {
94 return $self;
95 }
96 }
97
98 $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
99
100 $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 $self->read_filenames;
106
107 Fuse::main(
108 mountpoint=>$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
121 exit(0) if ($arg->{'fork'});
122
123 return 1;
124
125 };
126
127 =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 $self = shift;
140
141 system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
142
143 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 } else {
163 return 0;
164 }
165 }
166
167 my %files;
168 my %dirs;
169
170 sub read_filenames {
171 my $self = shift;
172
173 # 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
186 # 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 }
218 }
219
220 print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
221 }
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 foreach my $f (sort keys %files) {
256 if ($dirname) {
257 if ($f =~ s/^\E$dirname\Q\///) {
258 $out{$f}++ if ($f =~ /^[^\/]+$/);
259 }
260 } else {
261 $out{$f}++ if ($f =~ /^[^\/]+$/);
262 }
263 }
264 if (! %out) {
265 $out{'no files? bug?'}++;
266 }
267 print scalar keys %out," files in dir '$dirname'\n";
268 print "## ",join(" ",keys %out),"\n";
269 return (keys %out),0;
270 }
271
272 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 sub e_open {
284 # VFS sanity check; it keeps all the necessary state, not much to do here.
285 my $file = filename_fixup(shift);
286 my $flags = shift;
287
288 return -ENOENT() unless exists($files{$file});
289 return -EISDIR() unless exists($files{$file}{id});
290
291 read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
292
293 print "open '$file' ",length($files{$file}{cont})," bytes\n";
294 return 0;
295 }
296
297 sub e_read {
298 # return an error numeric, or binary/text string.
299 # (note: 0 means EOF, "0" will give a byte (ascii "0")
300 # to the reading program)
301 my ($file) = filename_fixup(shift);
302 my ($buf_len,$off) = @_;
303
304 return -ENOENT() unless exists($files{$file});
305
306 my $len = length($files{$file}{cont});
307
308 print "read '$file' [$len bytes] offset $off length $buf_len\n";
309
310 return -EINVAL() if ($off > $len);
311 return 0 if ($off == $len);
312
313 $buf_len = $len-$off if ($len - $off < $buf_len);
314
315 return substr($files{$file}{cont},$off,$buf_len);
316 }
317
318 sub clear_cont {
319 print "transaction rollback\n";
320 $dbh->rollback || die $dbh->errstr;
321 print "invalidate all cached content\n";
322 foreach my $f (keys %files) {
323 delete $files{$f}{cont};
324 }
325 print "begin new transaction\n";
326 #$dbh->begin_work || die $dbh->errstr;
327 }
328
329
330 sub update_db {
331 my $file = shift || die;
332
333 $files{$file}{ctime} = time();
334
335 my ($cont,$id) = (
336 $files{$file}{cont},
337 $files{$file}{id}
338 );
339
340 if (!$sth->{'update'}->execute($cont,$id)) {
341 print "update problem: ",$sth->{'update'}->errstr;
342 clear_cont;
343 return 0;
344 } else {
345 if (! $dbh->commit) {
346 print "ERROR: commit problem: ",$sth->{'update'}->errstr;
347 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 $file = filename_fixup(shift);
357 my ($buffer,$off) = @_;
358
359 return -ENOENT() unless exists($files{$file});
360
361 my $cont = $files{$file}{cont};
362 my $len = length($cont);
363
364 print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
365
366 $files{$file}{cont} = "";
367
368 $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
369 $files{$file}{cont} .= $buffer;
370 $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
371
372 $files{$file}{size} = length($files{$file}{cont});
373
374 if (! update_db($file)) {
375 return -ENOSYS();
376 } else {
377 return length($buffer);
378 }
379 }
380
381 sub e_truncate {
382 my $file = filename_fixup(shift);
383 my $size = shift;
384
385 print "truncate to $size\n";
386
387 $files{$file}{cont} = substr($files{$file}{cont},0,$size);
388 $files{$file}{size} = $size;
389 return 0
390 };
391
392
393 sub e_utime {
394 my ($atime,$mtime,$file) = @_;
395 $file = filename_fixup($file);
396
397 return -ENOENT() unless exists($files{$file});
398
399 print "utime '$file' $atime $mtime\n";
400
401 $files{$file}{time} = $mtime;
402 return 0;
403 }
404
405 sub e_statfs { return 255, 1, 1, 1, 1, 2 }
406
407 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 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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