use Fuse;
use DBI;
use Carp;
-use Proc::Simple;
use Data::Dumper;
+our $VERSION = '0.08';
-our $VERSION = '0.01';
+# block size for this filesystem
+use constant BLOCK => 1024;
=head1 NAME
use Fuse::DBI;
Fuse::DBI->mount( ... );
-See L<run> below for examples how to set parametars.
+See C<run> below for examples how to set parameters.
=head1 DESCRIPTION
-This module will use L<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
-available at L<http://sourceforge.net/projects/avf> to mount
+This module will use C<Fuse> module, part of C<FUSE (Filesystem in USErspace)>
+available at L<http://fuse.sourceforge.net/> to mount
your database as file system.
-That will give you posibility to use normal file-system tools (cat, grep, vi)
+That will give you possibility to use normal file-system tools (cat, grep, vi)
to manipulate data in database.
It's actually opposite of Oracle's intention to put everything into database.
Mount your database as filesystem.
+Let's suppose that your database have table C<files> with following structure:
+
+ id: int
+ filename: text
+ size: int
+ content: text
+ writable: boolean
+
+Following is example how to mount table like that to C</mnt>:
+
my $mnt = Fuse::DBI->mount({
- filenames => 'select name from filenamefilenames,
- read => 'sql read',
- update => 'sql update',
- dsn => 'DBI:Pg:dbname=webgui',
- user => 'database_user',
- password => 'database_password'
+ 'filenames' => 'select id,filename,size,writable from files',
+ 'read' => 'select content from files where id = ?',
+ 'update' => 'update files set content = ? where id = ?',
+ 'dsn' => 'DBI:Pg:dbname=test_db',
+ 'user' => 'database_user',
+ 'password' => 'database_password',
+ 'invalidate' => sub { ... },
});
+Options:
+
+=over 5
+
+=item filenames
+
+SQL query which returns C<id> (unique id for that row), C<filename>,
+C<size> and C<writable> boolean flag.
+
+=item read
+
+SQL query which returns only one column with content of file and has
+placeholder C<?> for C<id>.
+
+=item update
+
+SQL query with two pace-holders, one for new content and one for C<id>.
+
+=item dsn
+
+C<DBI> dsn to connect to (contains database driver and name of database).
+
+=item user
+
+User with which to connect to database
+
+=item password
+
+Password for connecting to database
+
+=item invalidate
+
+Optional anonymous code reference which will be executed when data is updated in
+database. It can be used as hook to delete cache (for example on-disk-cache)
+which is created from data edited through C<Fuse::DBI>.
+
+=item fork
+
+Optional flag which forks after mount so that executing script will continue
+running. Implementation is experimental.
+
+=back
+
=cut
my $dbh;
my $ctime_start;
sub read_filenames;
+sub fuse_module_loaded;
+
+# evil, evil way to solve this. It makes this module non-reentrant. But, since
+# fuse calls another copy of this script for each mount anyway, this shouldn't
+# be a problem.
+my $fuse_self;
sub mount {
my $class = shift;
print Dumper($arg);
+ unless ($self->fuse_module_loaded) {
+ print STDERR "no fuse module loaded. Trying sudo modprobe fuse!\n";
+ system "sudo modprobe fuse" || die "can't modprobe fuse using sudo!\n";
+ }
+
carp "mount needs 'dsn' to connect to (e.g. dsn => 'DBI:Pg:dbname=test')" unless ($arg->{'dsn'});
carp "mount needs 'mount' as mountpoint" unless ($arg->{'mount'});
# save (some) arguments in self
- $self->{$_} = $arg->{$_} foreach (qw(mount));
+ foreach (qw(mount invalidate)) {
+ $self->{$_} = $arg->{$_};
+ }
foreach (qw(filenames read update)) {
carp "mount needs '$_' SQL" unless ($arg->{$_});
}
- $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, { AutoCommit => 0 }) || die $DBI::errstr;
+ $ctime_start = time();
- print "start transaction\n";
- #$dbh->begin_work || die $dbh->errstr;
+ my $pid;
+ if ($arg->{'fork'}) {
+ $pid = fork();
+ die "fork() failed: $!" unless defined $pid;
+ # child will return to caller
+ if ($pid) {
+ my $counter = 4;
+ while ($counter && ! $self->is_mounted) {
+ select(undef, undef, undef, 0.5);
+ $counter--;
+ }
+ if ($self->is_mounted) {
+ return $self;
+ } else {
+ return undef;
+ }
+ }
+ }
+
+ $dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr;
- $sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
+ $sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
$sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
$sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
- $ctime_start = time();
- read_filenames;
-
- $self->{'proc'} = Proc::Simple->new();
- $self->{'proc'}->kill_on_destroy(1);
-
- $self->{'proc'}->start( sub {
- Fuse::main(
- mountpoint=>$arg->{'mount'},
- getattr=>\&e_getattr,
- getdir=>\&e_getdir,
- open=>\&e_open,
- statfs=>\&e_statfs,
- read=>\&e_read,
- write=>\&e_write,
- utime=>\&e_utime,
- truncate=>\&e_truncate,
- debug=>0,
- );
- } );
-
- confess "Fuse::main failed" if (! $self->{'proc'}->poll);
-
- $self ? return $self : return undef;
+ $self->{'sth'} = $sth;
+
+ $self->{'read_filenames'} = sub { $self->read_filenames };
+ $self->read_filenames;
+
+ $fuse_self = \$self;
+
+ Fuse::main(
+ mountpoint=>$arg->{'mount'},
+ getattr=>\&e_getattr,
+ getdir=>\&e_getdir,
+ open=>\&e_open,
+ statfs=>\&e_statfs,
+ read=>\&e_read,
+ write=>\&e_write,
+ utime=>\&e_utime,
+ truncate=>\&e_truncate,
+ unlink=>\&e_unlink,
+ rmdir=>\&e_unlink,
+ debug=>0,
+ );
+
+ exit(0) if ($arg->{'fork'});
+
+ return 1;
+
};
+=head2 is_mounted
+
+Check if fuse filesystem is mounted
+
+ if ($mnt->is_mounted) { ... }
+
+=cut
+
+sub is_mounted {
+ my $self = shift;
+
+ my $mounted = 0;
+ my $mount = $self->{'mount'} || confess "can't find mount point!";
+ if (open(MTAB, "/etc/mtab")) {
+ while(<MTAB>) {
+ $mounted = 1 if (/ $mount fuse /i);
+ }
+ close(MTAB);
+ } else {
+ warn "can't open /etc/mtab: $!";
+ }
+
+ return $mounted;
+}
+
+
=head2 umount
Unmount your database as filesystem.
sub umount {
my $self = shift;
- confess "no process running?" unless ($self->{'proc'});
+ if ($self->{'mount'} && $self->is_mounted) {
+ system "( fusermount -u ".$self->{'mount'}." 2>&1 ) >/dev/null";
+ if ($self->is_mounted) {
+ system "sudo umount ".$self->{'mount'} ||
+ return 0;
+ }
+ return 1;
+ }
- system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
+ return 0;
+}
- if ($self->{'proc'}->poll) {
- $self->{'proc'}->kill;
- return 1 if (! $self->{'proc'}->poll);
- } else {
- return 1;
+$SIG{'INT'} = sub {
+ if ($fuse_self && $$fuse_self->umount) {
+ print STDERR "umount called by SIG INT\n";
+ }
+};
+
+$SIG{'QUIT'} = sub {
+ if ($fuse_self && $$fuse_self->umount) {
+ print STDERR "umount called by SIG QUIT\n";
+ }
+};
+
+sub DESTROY {
+ my $self = shift;
+ if ($self->umount) {
+ print STDERR "umount called by DESTROY\n";
}
}
+=head2 fuse_module_loaded
+
+Checks if C<fuse> module is loaded in kernel.
+
+ die "no fuse module loaded in kernel"
+ unless (Fuse::DBI::fuse_module_loaded);
+
+This function in called by C<mount>, but might be useful alone also.
+
+=cut
+
+sub fuse_module_loaded {
+ my $lsmod = `lsmod`;
+ die "can't start lsmod: $!" unless ($lsmod);
+ if ($lsmod =~ m/fuse/s) {
+ return 1;
+ } else {
+ return 0;
+ }
+}
my %files;
-my %dirs;
sub read_filenames {
my $self = shift;
+ my $sth = $self->{'sth'} || die "no sth argument";
+
# create empty filesystem
(%files) = (
'.' => {
type => 0040,
mode => 0755,
},
+ '..' => {
+ type => 0040,
+ mode => 0755,
+ },
# a => {
# cont => "File 'a'.\n",
# type => 0100,
# read them in with sesible defaults
while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
+ $row->{'filename'} ||= 'NULL-'.$row->{'id'};
$files{$row->{'filename'}} = {
size => $row->{'size'},
mode => $row->{'writable'} ? 0644 : 0444,
id => $row->{'id'} || 99,
};
+
my $d;
foreach (split(m!/!, $row->{'filename'})) {
# first, entry is assumed to be file
if ($d) {
$files{$d} = {
- size => $dirs{$d}++,
mode => 0755,
type => 0040
};
}
}
- print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
+ print "found ",scalar(keys %files)," files\n";
}
$file =~ s,^/,,;
$file = '.' unless length($file);
return -ENOENT() unless exists($files{$file});
- my ($size) = $files{$file}{size} || 1;
- my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024);
+ my ($size) = $files{$file}{size} || 0;
+ my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,int(($size+BLOCK-1)/BLOCK),0,0,1,BLOCK);
my ($atime, $ctime, $mtime);
$atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start;
# 2 possible types of return values:
#return -ENOENT(); # or any other error you care to
- #print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n");
+ #print "getattr($file) ",join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n";
return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks);
}
my %out;
foreach my $f (sort keys %files) {
if ($dirname) {
- if ($f =~ s/^\E$dirname\Q\///) {
+ if ($f =~ s/^\Q$dirname\E\///) {
$out{$f}++ if ($f =~ /^[^\/]+$/);
}
} else {
return (keys %out),0;
}
+sub read_content {
+ my ($file,$id) = @_;
+
+ die "read_content needs file and id" unless ($file && $id);
+
+ $sth->{'read'}->execute($id) || die $sth->{'read'}->errstr;
+ $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
+ # I should modify ctime only if content in database changed
+ #$files{$file}{ctime} = time() unless ($files{$file}{ctime});
+ print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n";
+}
+
+
sub e_open {
# VFS sanity check; it keeps all the necessary state, not much to do here.
my $file = filename_fixup(shift);
return -ENOENT() unless exists($files{$file});
return -EISDIR() unless exists($files{$file}{id});
- if (!exists($files{$file}{cont})) {
- $sth->{'read'}->execute($files{$file}{id}) || die $sth->{'read'}->errstr;
- $files{$file}{cont} = $sth->{'read'}->fetchrow_array;
- print "file '$file' content read in cache\n";
- }
+ read_content($file,$files{$file}{id}) unless exists($files{$file}{cont});
+
+ $files{$file}{cont} ||= '';
print "open '$file' ",length($files{$file}{cont})," bytes\n";
return 0;
}
return -EINVAL() if ($off > $len);
return 0 if ($off == $len);
- $buf_len = $buf_len-$off if ($off+$buf_len > $len);
+ $buf_len = $len-$off if ($len - $off < $buf_len);
return substr($files{$file}{cont},$off,$buf_len);
}
print "invalidate all cached content\n";
foreach my $f (keys %files) {
delete $files{$f}{cont};
+ delete $files{$f}{ctime};
}
print "begin new transaction\n";
- $dbh->begin_work || die $dbh->errstr;
+ #$dbh->begin_work || die $dbh->errstr;
}
$files{$file}{ctime} = time();
- if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {
+ my ($cont,$id) = (
+ $files{$file}{cont},
+ $files{$file}{id}
+ );
+
+ if (!$sth->{'update'}->execute($cont,$id)) {
print "update problem: ",$sth->{'update'}->errstr;
clear_cont;
return 0;
return 0;
}
print "updated '$file' [",$files{$file}{id},"]\n";
+
+ $$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'});
}
return 1;
}
sub e_write {
my $file = filename_fixup(shift);
- my ($buf_len,$off) = @_;
+ my ($buffer,$off) = @_;
return -ENOENT() unless exists($files{$file});
- my $len = length($files{$file}{cont});
+ my $cont = $files{$file}{cont};
+ my $len = length($cont);
- print "write '$file' [$len bytes] offset $off length\n";
+ print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
- $files{$file}{cont} =
- substr($files{$file}{cont},0,$off) .
- $buf_len .
- substr($files{$file}{cont},$off+length($buf_len));
+ $files{$file}{cont} = "";
+
+ $files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
+ $files{$file}{cont} .= $buffer;
+ $files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len);
+
+ $files{$file}{size} = length($files{$file}{cont});
if (! update_db($file)) {
return -ENOSYS();
} else {
- return length($buf_len);
+ return length($buffer);
}
}
my $file = filename_fixup(shift);
my $size = shift;
+ print "truncate to $size\n";
+
$files{$file}{cont} = substr($files{$file}{cont},0,$size);
+ $files{$file}{size} = $size;
return 0
};
return 0;
}
-sub e_statfs { return 255, 1, 1, 1, 1, 2 }
+sub e_statfs {
+
+ my $size = 0;
+ my $inodes = 0;
+
+ foreach my $f (keys %files) {
+ if ($f !~ /(^|\/)\.\.?$/) {
+ $size += $files{$f}{size} || 0;
+ $inodes++;
+ }
+ print "$inodes: $f [$size]\n";
+ }
+
+ $size = int(($size+BLOCK-1)/BLOCK);
+
+ my @ret = (255, $inodes, 1, $size, $size-1, BLOCK);
+
+ #print "statfs: ",join(",",@ret),"\n";
+
+ return @ret;
+}
+
+sub e_unlink {
+ my $file = filename_fixup(shift);
+# if (exists( $dirs{$file} )) {
+# print "unlink '$file' will re-read template names\n";
+# print Dumper($fuse_self);
+# $$fuse_self->{'read_filenames'}->();
+# return 0;
+ if (exists( $files{$file} )) {
+ print "unlink '$file' will invalidate cache\n";
+ read_content($file,$files{$file}{id});
+ return 0;
+ }
+
+ return -ENOENT();
+}
1;
__END__
Nothing.
+=head1 BUGS
+
+Size information (C<ls -s>) is wrong. It's a problem in upstream Fuse module
+(for which I'm to blame lately), so when it gets fixes, C<Fuse::DBI> will
+automagically pick it up.
+
=head1 SEE ALSO
C<FUSE (Filesystem in USErspace)> website
-L<http://sourceforge.net/projects/avf>
+L<http://fuse.sourceforge.net/>
+
+Example for WebGUI which comes with this distribution in
+directory C<examples/webgui.pl>. It also contains a lot of documentation
+about design of this module, usage and limitations.
=head1 AUTHOR
projects / Fuse-DBI / blobdiff