1 |
#!/usr/bin/perl |
2 |
|
3 |
package Fuse::DBI; |
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|
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use 5.008; |
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use strict; |
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use warnings; |
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|
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use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR); |
10 |
use Fuse; |
11 |
use DBI; |
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use Carp; |
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use Data::Dumper; |
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|
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|
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our $VERSION = '0.07'; |
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|
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=head1 NAME |
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|
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Fuse::DBI - mount your database as filesystem and use it |
21 |
|
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=head1 SYNOPSIS |
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|
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use Fuse::DBI; |
25 |
Fuse::DBI->mount( ... ); |
26 |
|
27 |
See C<run> below for examples how to set parameters. |
28 |
|
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=head1 DESCRIPTION |
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|
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This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)> |
32 |
available at L<http://fuse.sourceforge.net/> to mount |
33 |
your database as file system. |
34 |
|
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That will give you possibility to use normal file-system tools (cat, grep, vi) |
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to manipulate data in database. |
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|
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It's actually opposite of Oracle's intention to put everything into database. |
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|
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|
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=head1 METHODS |
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|
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=cut |
44 |
|
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=head2 mount |
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|
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Mount your database as filesystem. |
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|
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Let's suppose that your database have table C<files> with following structure: |
50 |
|
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id: int |
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filename: text |
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size: int |
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content: text |
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writable: boolean |
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|
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Following is example how to mount table like that to C</mnt>: |
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|
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my $mnt = Fuse::DBI->mount({ |
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'filenames' => 'select id,filename,size,writable from files', |
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'read' => 'select content from files where id = ?', |
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'update' => 'update files set content = ? where id = ?', |
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'dsn' => 'DBI:Pg:dbname=test_db', |
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'user' => 'database_user', |
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'password' => 'database_password', |
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'invalidate' => sub { ... }, |
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}); |
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|
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Options: |
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|
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=over 5 |
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|
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=item filenames |
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|
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SQL query which returns C<id> (unique id for that row), C<filename>, |
76 |
C<size> and C<writable> boolean flag. |
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|
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=item read |
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|
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SQL query which returns only one column with content of file and has |
81 |
placeholder C<?> for C<id>. |
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|
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=item update |
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|
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SQL query with two pace-holders, one for new content and one for C<id>. |
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|
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=item dsn |
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|
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C<DBI> dsn to connect to (contains database driver and name of database). |
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|
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=item user |
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|
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User with which to connect to database |
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|
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=item password |
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|
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Password for connecting to database |
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|
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=item invalidate |
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|
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Optional anonymous code reference which will be executed when data is updated in |
102 |
database. It can be used as hook to delete cache (for example on-disk-cache) |
103 |
which is created from data edited through C<Fuse::DBI>. |
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|
105 |
=item fork |
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|
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Optional flag which forks after mount so that executing script will continue |
108 |
running. Implementation is experimental. |
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|
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=back |
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|
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=cut |
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|
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my $dbh; |
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my $sth; |
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my $ctime_start; |
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|
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sub read_filenames; |
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sub fuse_module_loaded; |
120 |
|
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# evil, evil way to solve this. It makes this module non-reentrant. But, since |
122 |
# fuse calls another copy of this script for each mount anyway, this shouldn't |
123 |
# be a problem. |
124 |
my $fuse_self; |
125 |
|
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sub mount { |
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my $class = shift; |
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my $self = {}; |
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bless($self, $class); |
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|
131 |
my $arg = shift; |
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|
133 |
print Dumper($arg); |
134 |
|
135 |
unless ($self->fuse_module_loaded) { |
136 |
print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n"; |
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system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n"; |
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} |
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|
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carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'}); |
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carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'}); |
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|
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# save (some) arguments in self |
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foreach (qw(mount invalidate)) { |
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$self->{$_} = $arg->{$_}; |
146 |
} |
147 |
|
148 |
foreach (qw(filenames read update)) { |
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carp "mount needs '$_' SQL" unless ($arg->{$_}); |
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} |
151 |
|
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$ctime_start = time(); |
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|
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my $pid; |
155 |
if ($arg->{'fork'}) { |
156 |
$pid = fork(); |
157 |
die "fork() failed: $!" unless defined $pid; |
158 |
# child will return to caller |
159 |
if ($pid) { |
160 |
my $counter = 4; |
161 |
while ($counter && ! $self->is_mounted) { |
162 |
select(undef, undef, undef, 0.5); |
163 |
$counter--; |
164 |
} |
165 |
if ($self->is_mounted) { |
166 |
return $self; |
167 |
} else { |
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return undef; |
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} |
170 |
} |
171 |
} |
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|
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$dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr; |
174 |
|
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$sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr(); |
176 |
|
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$sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr(); |
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$sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr(); |
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|
180 |
|
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$self->{'sth'} = $sth; |
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|
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$self->{'read_filenames'} = sub { $self->read_filenames }; |
184 |
$self->read_filenames; |
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|
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$fuse_self = \$self; |
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|
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Fuse::main( |
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mountpoint=>$arg->{'mount'}, |
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getattr=>\&e_getattr, |
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getdir=>\&e_getdir, |
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open=>\&e_open, |
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statfs=>\&e_statfs, |
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read=>\&e_read, |
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write=>\&e_write, |
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utime=>\&e_utime, |
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truncate=>\&e_truncate, |
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unlink=>\&e_unlink, |
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rmdir=>\&e_unlink, |
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debug=>0, |
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); |
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|
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exit(0) if ($arg->{'fork'}); |
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|
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return 1; |
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|
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}; |
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|
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=head2 is_mounted |
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|
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Check if fuse filesystem is mounted |
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|
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if ($mnt->is_mounted) { ... } |
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|
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=cut |
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|
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sub is_mounted { |
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my $self = shift; |
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|
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my $mounted = 0; |
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my $mount = $self->{'mount'} || confess "can't find mount point!"; |
222 |
if (open(MTAB, "/etc/mtab")) { |
223 |
while(<MTAB>) { |
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$mounted = 1 if (/ $mount fuse /i); |
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} |
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close(MTAB); |
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} else { |
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warn "can't open /etc/mtab: $!"; |
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} |
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|
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return $mounted; |
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} |
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|
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|
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=head2 umount |
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|
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Unmount your database as filesystem. |
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|
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$mnt->umount; |
240 |
|
241 |
This will also kill background process which is translating |
242 |
database to filesystem. |
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|
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=cut |
245 |
|
246 |
sub umount { |
247 |
my $self = shift; |
248 |
|
249 |
if ($self->{'mount'} && $self->is_mounted) { |
250 |
system "fusermount -u ".$self->{'mount'}." 2>&1 >/dev/null" || |
251 |
system "sudo umount ".$self->{'mount'} || |
252 |
return 0; |
253 |
return 1; |
254 |
} |
255 |
|
256 |
return 0; |
257 |
} |
258 |
|
259 |
$SIG{'INT'} = sub { |
260 |
if ($fuse_self && $$fuse_self->umount) { |
261 |
print STDERR "umount called by SIG INT\n"; |
262 |
} |
263 |
}; |
264 |
|
265 |
$SIG{'QUIT'} = sub { |
266 |
if ($fuse_self && $$fuse_self->umount) { |
267 |
print STDERR "umount called by SIG QUIT\n"; |
268 |
} |
269 |
}; |
270 |
|
271 |
sub DESTROY { |
272 |
my $self = shift; |
273 |
if ($self->umount) { |
274 |
print STDERR "umount called by DESTROY\n"; |
275 |
} |
276 |
} |
277 |
|
278 |
=head2 fuse_module_loaded |
279 |
|
280 |
Checks if C<fuse> module is loaded in kernel. |
281 |
|
282 |
die "no fuse module loaded in kernel" |
283 |
unless (Fuse::DBI::fuse_module_loaded); |
284 |
|
285 |
This function in called by C<mount>, but might be useful alone also. |
286 |
|
287 |
=cut |
288 |
|
289 |
sub fuse_module_loaded { |
290 |
my $lsmod = `lsmod`; |
291 |
die "can't start lsmod: $!" unless ($lsmod); |
292 |
if ($lsmod =~ m/fuse/s) { |
293 |
return 1; |
294 |
} else { |
295 |
return 0; |
296 |
} |
297 |
} |
298 |
|
299 |
my %files; |
300 |
|
301 |
sub read_filenames { |
302 |
my $self = shift; |
303 |
|
304 |
my $sth = $self->{'sth'} || die "no sth argument"; |
305 |
|
306 |
# create empty filesystem |
307 |
(%files) = ( |
308 |
'.' => { |
309 |
type => 0040, |
310 |
mode => 0755, |
311 |
}, |
312 |
'..' => { |
313 |
type => 0040, |
314 |
mode => 0755, |
315 |
}, |
316 |
# a => { |
317 |
# cont => "File 'a'.\n", |
318 |
# type => 0100, |
319 |
# ctime => time()-2000 |
320 |
# }, |
321 |
); |
322 |
|
323 |
# fetch new filename list from database |
324 |
$sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr(); |
325 |
|
326 |
# read them in with sesible defaults |
327 |
while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) { |
328 |
$files{$row->{'filename'}} = { |
329 |
size => $row->{'size'}, |
330 |
mode => $row->{'writable'} ? 0644 : 0444, |
331 |
id => $row->{'id'} || 99, |
332 |
}; |
333 |
|
334 |
my $d; |
335 |
foreach (split(m!/!, $row->{'filename'})) { |
336 |
# first, entry is assumed to be file |
337 |
if ($d) { |
338 |
$files{$d} = { |
339 |
mode => 0755, |
340 |
type => 0040 |
341 |
}; |
342 |
$files{$d.'/.'} = { |
343 |
mode => 0755, |
344 |
type => 0040 |
345 |
}; |
346 |
$files{$d.'/..'} = { |
347 |
mode => 0755, |
348 |
type => 0040 |
349 |
}; |
350 |
} |
351 |
$d .= "/" if ($d); |
352 |
$d .= "$_"; |
353 |
} |
354 |
} |
355 |
|
356 |
print "found ",scalar(keys %files)," files\n"; |
357 |
} |
358 |
|
359 |
|
360 |
sub filename_fixup { |
361 |
my ($file) = shift; |
362 |
$file =~ s,^/,,; |
363 |
$file = '.' unless length($file); |
364 |
return $file; |
365 |
} |
366 |
|
367 |
sub e_getattr { |
368 |
my ($file) = filename_fixup(shift); |
369 |
$file =~ s,^/,,; |
370 |
$file = '.' unless length($file); |
371 |
return -ENOENT() unless exists($files{$file}); |
372 |
my ($size) = $files{$file}{size} || 1024; |
373 |
my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+1023)/1024),0,0,1,1024); |
374 |
my ($atime, $ctime, $mtime); |
375 |
$atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start; |
376 |
|
377 |
my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode}; |
378 |
|
379 |
# 2 possible types of return values: |
380 |
#return -ENOENT(); # or any other error you care to |
381 |
print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n"; |
382 |
return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks); |
383 |
} |
384 |
|
385 |
sub e_getdir { |
386 |
my ($dirname) = shift; |
387 |
$dirname =~ s!^/!!; |
388 |
# return as many text filenames as you like, followed by the retval. |
389 |
print((scalar keys %files)." files total\n"); |
390 |
my %out; |
391 |
foreach my $f (sort keys %files) { |
392 |
if ($dirname) { |
393 |
if ($f =~ s/^\Q$dirname\E\///) { |
394 |
$out{$f}++ if ($f =~ /^[^\/]+$/); |
395 |
} |
396 |
} else { |
397 |
$out{$f}++ if ($f =~ /^[^\/]+$/); |
398 |
} |
399 |
} |
400 |
if (! %out) { |
401 |
$out{'no files? bug?'}++; |
402 |
} |
403 |
print scalar keys %out," files in dir '$dirname'\n"; |
404 |
print "## ",join(" ",keys %out),"\n"; |
405 |
return (keys %out),0; |
406 |
} |
407 |
|
408 |
sub read_content { |
409 |
my ($file,$id) = @_; |
410 |
|
411 |
die "read_content needs file and id" unless ($file && $id); |
412 |
|
413 |
$sth->{'read'}->execute($id) || die $sth->{'read'}->errstr; |
414 |
$files{$file}{cont} = $sth->{'read'}->fetchrow_array; |
415 |
# I should modify ctime only if content in database changed |
416 |
#$files{$file}{ctime} = time() unless ($files{$file}{ctime}); |
417 |
print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n"; |
418 |
} |
419 |
|
420 |
|
421 |
sub e_open { |
422 |
# VFS sanity check; it keeps all the necessary state, not much to do here. |
423 |
my $file = filename_fixup(shift); |
424 |
my $flags = shift; |
425 |
|
426 |
return -ENOENT() unless exists($files{$file}); |
427 |
return -EISDIR() unless exists($files{$file}{id}); |
428 |
|
429 |
read_content($file,$files{$file}{id}) unless exists($files{$file}{cont}); |
430 |
|
431 |
print "open '$file' ",length($files{$file}{cont})," bytes\n"; |
432 |
return 0; |
433 |
} |
434 |
|
435 |
sub e_read { |
436 |
# return an error numeric, or binary/text string. |
437 |
# (note: 0 means EOF, "0" will give a byte (ascii "0") |
438 |
# to the reading program) |
439 |
my ($file) = filename_fixup(shift); |
440 |
my ($buf_len,$off) = @_; |
441 |
|
442 |
return -ENOENT() unless exists($files{$file}); |
443 |
|
444 |
my $len = length($files{$file}{cont}); |
445 |
|
446 |
print "read '$file' [$len bytes] offset $off length $buf_len\n"; |
447 |
|
448 |
return -EINVAL() if ($off > $len); |
449 |
return 0 if ($off == $len); |
450 |
|
451 |
$buf_len = $len-$off if ($len - $off < $buf_len); |
452 |
|
453 |
return substr($files{$file}{cont},$off,$buf_len); |
454 |
} |
455 |
|
456 |
sub clear_cont { |
457 |
print "transaction rollback\n"; |
458 |
$dbh->rollback || die $dbh->errstr; |
459 |
print "invalidate all cached content\n"; |
460 |
foreach my $f (keys %files) { |
461 |
delete $files{$f}{cont}; |
462 |
delete $files{$f}{ctime}; |
463 |
} |
464 |
print "begin new transaction\n"; |
465 |
#$dbh->begin_work || die $dbh->errstr; |
466 |
} |
467 |
|
468 |
|
469 |
sub update_db { |
470 |
my $file = shift || die; |
471 |
|
472 |
$files{$file}{ctime} = time(); |
473 |
|
474 |
my ($cont,$id) = ( |
475 |
$files{$file}{cont}, |
476 |
$files{$file}{id} |
477 |
); |
478 |
|
479 |
if (!$sth->{'update'}->execute($cont,$id)) { |
480 |
print "update problem: ",$sth->{'update'}->errstr; |
481 |
clear_cont; |
482 |
return 0; |
483 |
} else { |
484 |
if (! $dbh->commit) { |
485 |
print "ERROR: commit problem: ",$sth->{'update'}->errstr; |
486 |
clear_cont; |
487 |
return 0; |
488 |
} |
489 |
print "updated '$file' [",$files{$file}{id},"]\n"; |
490 |
|
491 |
$$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'}); |
492 |
} |
493 |
return 1; |
494 |
} |
495 |
|
496 |
sub e_write { |
497 |
my $file = filename_fixup(shift); |
498 |
my ($buffer,$off) = @_; |
499 |
|
500 |
return -ENOENT() unless exists($files{$file}); |
501 |
|
502 |
my $cont = $files{$file}{cont}; |
503 |
my $len = length($cont); |
504 |
|
505 |
print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n"; |
506 |
|
507 |
$files{$file}{cont} = ""; |
508 |
|
509 |
$files{$file}{cont} .= substr($cont,0,$off) if ($off > 0); |
510 |
$files{$file}{cont} .= $buffer; |
511 |
$files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len); |
512 |
|
513 |
$files{$file}{size} = length($files{$file}{cont}); |
514 |
|
515 |
if (! update_db($file)) { |
516 |
return -ENOSYS(); |
517 |
} else { |
518 |
return length($buffer); |
519 |
} |
520 |
} |
521 |
|
522 |
sub e_truncate { |
523 |
my $file = filename_fixup(shift); |
524 |
my $size = shift; |
525 |
|
526 |
print "truncate to $size\n"; |
527 |
|
528 |
$files{$file}{cont} = substr($files{$file}{cont},0,$size); |
529 |
$files{$file}{size} = $size; |
530 |
return 0 |
531 |
}; |
532 |
|
533 |
|
534 |
sub e_utime { |
535 |
my ($atime,$mtime,$file) = @_; |
536 |
$file = filename_fixup($file); |
537 |
|
538 |
return -ENOENT() unless exists($files{$file}); |
539 |
|
540 |
print "utime '$file' $atime $mtime\n"; |
541 |
|
542 |
$files{$file}{time} = $mtime; |
543 |
return 0; |
544 |
} |
545 |
|
546 |
sub e_statfs { |
547 |
|
548 |
my $size = 0; |
549 |
my $inodes = 0; |
550 |
|
551 |
foreach my $f (keys %files) { |
552 |
if ($f !~ /(^|\/)\.\.?$/) { |
553 |
$size += $files{$f}{size} || 0; |
554 |
$inodes++; |
555 |
} |
556 |
print "$inodes: $f [$size]\n"; |
557 |
} |
558 |
|
559 |
$size = int(($size+1023)/1024); |
560 |
|
561 |
my @ret = (255, $inodes+1000, $inodes, $size, $size-10, 1024); |
562 |
|
563 |
print "statfs: ",join(",",@ret),"\n"; |
564 |
|
565 |
return @ret; |
566 |
} |
567 |
|
568 |
sub e_unlink { |
569 |
my $file = filename_fixup(shift); |
570 |
|
571 |
# if (exists( $dirs{$file} )) { |
572 |
# print "unlink '$file' will re-read template names\n"; |
573 |
# print Dumper($fuse_self); |
574 |
# $$fuse_self->{'read_filenames'}->(); |
575 |
# return 0; |
576 |
if (exists( $files{$file} )) { |
577 |
print "unlink '$file' will invalidate cache\n"; |
578 |
read_content($file,$files{$file}{id}); |
579 |
return 0; |
580 |
} |
581 |
|
582 |
return -ENOENT(); |
583 |
} |
584 |
1; |
585 |
__END__ |
586 |
|
587 |
=head1 EXPORT |
588 |
|
589 |
Nothing. |
590 |
|
591 |
=head1 BUGS |
592 |
|
593 |
Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module |
594 |
(for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will |
595 |
automagically pick it up. |
596 |
|
597 |
=head1 SEE ALSO |
598 |
|
599 |
C<FUSE (Filesystem in USErspace)> website |
600 |
L<http://fuse.sourceforge.net/> |
601 |
|
602 |
Example for WebGUI which comes with this distribution in |
603 |
directory C<examples/webgui.pl>. It also contains a lot of documentation |
604 |
about design of this module, usage and limitations. |
605 |
|
606 |
=head1 AUTHOR |
607 |
|
608 |
Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt> |
609 |
|
610 |
=head1 COPYRIGHT AND LICENSE |
611 |
|
612 |
Copyright (C) 2004 by Dobrica Pavlinusic |
613 |
|
614 |
This library is free software; you can redistribute it and/or modify |
615 |
it under the same terms as Perl itself, either Perl version 5.8.4 or, |
616 |
at your option, any later version of Perl 5 you may have available. |
617 |
|
618 |
|
619 |
=cut |
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|