X-Git-Url: http://git.rot13.org/?p=Fuse-DBI;a=blobdiff_plain;f=DBI.pm;h=425822dccc1b8ac4bd9161ce80297e0d24156bba;hp=96b3ea36f3cb697f2473efa6075629d891553130;hb=HEAD;hpb=414d242c9ec3d06490ed022c99e3d01e80bf82db

diff --git a/DBI.pm b/DBI.pm
index 96b3ea3..425822d 100755
--- a/DBI.pm
+++ b/DBI.pm
@@ -10,11 +10,12 @@ use POSIX qw(ENOENT EISDIR EINVAL ENOSYS O_RDWR);
 use Fuse;
 use DBI;
 use Carp;
-use Proc::Simple;
 use Data::Dumper;
 
+our $VERSION = '0.09_1';
 
-our $VERSION = '0.02';
+# block size for this filesystem
+use constant BLOCK => 1024;
 
 =head1 NAME
 
@@ -25,15 +26,15 @@ Fuse::DBI - mount your database as filesystem and use it
   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.
@@ -47,13 +48,86 @@ 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 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
+
+There is also alternative way which can generate C<read> and C<update>
+queries on the fly:
+
   my $mnt = Fuse::DBI->mount({
-	filenames => 'select name from filenamefilenames,
-	read => 'sql read',
-	update => 'sql update',
-	dsn => 'DBI:Pg:dbname=webgui',
-	user => 'database_user',
-	password => 'database_password'
+	'filenames' => 'select id,filename,size,writable from files',
+	'read' => sub {
+		my ($path,$file) = @_;
+		return( 'select content from files where id = ?', $file->{row}->{id} );
+	},
+	'update' => sub {
+		my ($path,$file) = @_;
+		return( 'update files set content = ? where id = ?', $file->{row}->{id} );
+	},
+	'dsn' => 'DBI:Pg:dbname=test_db',
+	'user' => 'database_user',
+	'password' => 'database_password',
+	'invalidate' => sub { ... },
   });
 
 =cut
@@ -63,6 +137,14 @@ my $sth;
 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;
+
+my $debug = 0;
 
 sub mount {
 	my $class = shift;
@@ -73,53 +155,114 @@ sub mount {
 
 	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();
+
+	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;
 
-	print "start transaction\n";
-	$dbh->begin_work || die $dbh->errstr;
+	$sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
 
-	$sth->{filenames} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr();
+	$self->{'sth'} = $sth;
+	$self->{'dbh'} = $dbh;
 
-	$sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr();
-	$sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr();
+	$self->{'read_filenames'} = sub { $self->read_filenames };
+	$self->read_filenames;
 
-	$ctime_start = time();
+	foreach my $op (qw/read update/) {
+		if (ref($arg->{ $op }) ne 'CODE') {
+			$self->{ $op . '_ref' } = sub {
+				my $row = shift;
+				return ($arg->{ $op }, $row->{'id'});
+			}
+		} else {
+			$self->{ $op . '_ref' } = $arg->{ $op };
+		}
+	}
+
+	$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=>$debug,
+	);
+	
+	exit(0) if ($arg->{'fork'});
+
+	return 1;
 
-	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;
 };
 
+=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.
@@ -134,63 +277,110 @@ database to 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";
+		sleep 1;
+		if ($self->is_mounted) {
+			system "sudo umount ".$self->{'mount'} ||
+			return 0;
+		}
+		return 1;
+	}
+
+	return 0;
+}
+
+$SIG{'INT'} = sub {
+	if ($fuse_self && $fuse_self->can('umount')) {
+		print STDERR "umount called by SIG INT\n";
+	}
+};
+
+$SIG{'QUIT'} = sub {
+	if ($fuse_self && $fuse_self->can('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
 
-	system "fusermount -u ".$self->{'mount'} || croak "umount error: $!";
+Checks if C<fuse> module is loaded in kernel.
 
-	if ($self->{'proc'}->poll) {
-		$self->{'proc'}->kill;
-		return 1 if (! $self->{'proc'}->poll);
-	} else {
+  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;
+my $files;
 
 sub read_filenames {
 	my $self = shift;
 
+	my $sth = $self->{'sth'} || die "no sth argument";
+
 	# create empty filesystem
-	(%files) = (
+	$files = {
 		'.' => {
 			type => 0040,
 			mode => 0755,
 		},
+		'..' => {
+			type => 0040,
+			mode => 0755,
+		},
 	#	a => {
 	#		cont => "File 'a'.\n",
 	#		type => 0100,
 	#		ctime => time()-2000
 	#	},
-	);
+	};
 
 	# fetch new filename list from database
 	$sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr();
 
 	# read them in with sesible defaults
 	while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) {
-		$files{$row->{'filename'}} = {
+		$row->{'filename'} ||= 'NULL-'.$row->{'id'};
+		$files->{$row->{'filename'}} = {
 			size => $row->{'size'},
 			mode => $row->{'writable'} ? 0644 : 0444,
-			id => $row->{'id'} || 99,
+			id => $row->{'id'} || undef,
+			row => $row,
 		};
 
+
 		my $d;
 		foreach (split(m!/!, $row->{'filename'})) {
 			# first, entry is assumed to be file
 			if ($d) {
-				$files{$d} = {
-						size => $dirs{$d}++,
+				$files->{$d} = {
 						mode => 0755,
 						type => 0040
 				};
-				$files{$d.'/.'} = {
+				$files->{$d.'/.'} = {
 						mode => 0755,
 						type => 0040
 				};
-				$files{$d.'/..'} = {
+				$files->{$d.'/..'} = {
 						mode => 0755,
 						type => 0040
 				};
@@ -200,7 +390,7 @@ sub read_filenames {
 		}
 	}
 
-	print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n";
+	print "found ",scalar(keys %{$files})," files\n";
 }
 
 
@@ -215,17 +405,17 @@ sub e_getattr {
 	my ($file) = filename_fixup(shift);
 	$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, $blksize) = (0,0,0,1,0,0,1,1024);
+	return -ENOENT() unless exists($files->{$file});
+	my ($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;
+	$atime = $ctime = $mtime = $files->{$file}->{ctime} || $ctime_start;
 
-	my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode};
+	my ($modes) = (($files->{$file}->{type} || 0100)<<9) + $files->{$file}->{mode};
 
 	# 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);
 }
 
@@ -233,11 +423,11 @@ sub e_getdir {
 	my ($dirname) = shift;
 	$dirname =~ s!^/!!;
 	# return as many text filenames as you like, followed by the retval.
-	print((scalar keys %files)." files total\n");
+	print((scalar keys %{$files})." files total\n");
 	my %out;
-	foreach my $f (sort keys %files) {
+	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 {
@@ -252,20 +442,37 @@ sub e_getdir {
 	return (keys %out),0;
 }
 
+sub read_content {
+	my $file = shift || die "need file";
+
+	warn "# read_content($file)\n" if ($debug);
+
+	my @args = $fuse_self->{'read_ref'}->($files->{$file});
+	my $sql = shift @args || die "need SQL for $file";
+
+	$fuse_self->{'read_sth'}->{$sql} ||= $fuse_self->{dbh}->prepare($sql) || die $dbh->errstr();
+	my $sth = $fuse_self->{'read_sth'}->{$sql} || die;
+
+	$sth->execute(@args) || die $sth->errstr;
+	$files->{$file}->{cont} = $sth->fetchrow_array;
+	# I should modify ctime only if content in database changed
+	#$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);
 	my $flags = shift;
 
-	return -ENOENT() unless exists($files{$file});
-	return -EISDIR() unless exists($files{$file}{id});
+	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";
-	}
-	print "open '$file' ",length($files{$file}{cont})," bytes\n";
+	read_content($file,$files->{$file}->{id}) unless exists($files->{$file}->{cont});
+
+	$files->{$file}->{cont} ||= '';
+	print "open '$file' ",length($files->{$file}->{cont})," bytes\n";
 	return 0;
 }
 
@@ -276,48 +483,68 @@ sub e_read {
 	my ($file) = filename_fixup(shift);
 	my ($buf_len,$off) = @_;
 
-	return -ENOENT() unless exists($files{$file});
+	return -ENOENT() unless exists($files->{$file});
 
-	my $len = length($files{$file}{cont});
+	my $len = length($files->{$file}->{cont});
 
 	print "read '$file' [$len bytes] offset $off length $buf_len\n";
 
 	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);
+	return substr($files->{$file}->{cont},$off,$buf_len);
 }
 
 sub clear_cont {
 	print "transaction rollback\n";
 	$dbh->rollback || die $dbh->errstr;
 	print "invalidate all cached content\n";
-	foreach my $f (keys %files) {
-		delete $files{$f}{cont};
+	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;
 }
 
 
 sub update_db {
-	my $file = shift || die;
+	my $file = shift || die "need file";
+
+	$files->{$file}->{ctime} = time();
+
+	my ($cont,$id) = (
+		$files->{$file}->{cont},
+		$files->{$file}->{id}
+	);
+
+	my @args = $fuse_self->{'update_ref'}->($files->{$file});
+
+	my $sql = shift @args || die "need SQL for $file";
+
+	unshift @args, $files->{$file}->{cont} if ($#args == 0);
 
-	$files{$file}{ctime} = time();
+	warn "## SQL: $sql\n# files->{$file} = ", Dumper($files->{$file}), $/ if ($debug);
 
-	if (!$sth->{'update'}->execute($files{$file}{cont},$files{$file}{id})) {
-		print "update problem: ",$sth->{'update'}->errstr;
+	my $sth = $fuse_self->{'update_sth'}->{$sql}
+		||= $fuse_self->{dbh}->prepare($sql)
+		|| die $dbh->errstr();
+
+	if (!$sth->execute(@args)) {
+		print "update problem: ",$sth->errstr;
 		clear_cont;
 		return 0;
 	} else {
 		if (! $dbh->commit) {
-			print "ERROR: commit problem: ",$sth->{'update'}->errstr;
+			print "ERROR: commit problem: ",$sth->errstr;
 			clear_cont;
 			return 0;
 		}
-		print "updated '$file' [",$files{$file}{id},"]\n";
+		print "updated '$file' [",$files->{$file}->{id},"]\n";
+
+		$fuse_self->{'invalidate'}->() if ($fuse_self->can('invalidate'));
 	}
 	return 1;
 }
@@ -326,20 +553,20 @@ sub e_write {
 	my $file = filename_fixup(shift);
 	my ($buffer,$off) = @_;
 
-	return -ENOENT() unless exists($files{$file});
+	return -ENOENT() unless exists($files->{$file});
 
-	my $cont = $files{$file}{cont};
+	my $cont = $files->{$file}->{cont};
 	my $len = length($cont);
 
 	print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n";
 
-	$files{$file}{cont} = "";
+	$files->{$file}->{cont} = "";
 
-	$files{$file}{cont} .= substr($cont,0,$off) if ($off > 0);
-	$files{$file}{cont} .= $buffer;
-	$files{$file}{cont} .= substr($cont,-($off+length($buffer))) if ($off+length($buffer) > $len);
+	$files->{$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});
+	$files->{$file}->{size} = length($files->{$file}->{cont});
 
 	if (! update_db($file)) {
 		return -ENOSYS();
@@ -354,8 +581,8 @@ sub e_truncate {
 
 	print "truncate to $size\n";
 
-	$files{$file}{cont} = substr($files{$file}{cont},0,$size);
-	$files{$file}{size} = $size;
+	$files->{$file}->{cont} = substr($files->{$file}->{cont},0,$size);
+	$files->{$file}->{size} = $size;
 	return 0
 };
 
@@ -364,16 +591,52 @@ sub e_utime {
 	my ($atime,$mtime,$file) = @_;
 	$file = filename_fixup($file);
 
-	return -ENOENT() unless exists($files{$file});
+	return -ENOENT() unless exists($files->{$file});
 
 	print "utime '$file' $atime $mtime\n";
 
-	$files{$file}{time} = $mtime;
+	$files->{$file}->{time} = $mtime;
 	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__
 
@@ -381,10 +644,20 @@ __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