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#!/usr/bin/perl |
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|
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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); |
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use Fuse; |
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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 = '0.04'; |
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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 |
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|
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=head1 SYNOPSIS |
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|
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use Fuse::DBI; |
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Fuse::DBI->mount( ... ); |
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|
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See C<run> below for examples how to set parameters. |
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|
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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)> |
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available at L<http://sourceforge.net/projects/avf> to mount |
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your database as file system. |
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|
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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 |
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|
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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: |
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|
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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>, |
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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 |
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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 |
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database. It can be used as hook to delete cache (for example on-disk-cache) |
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which is created from data edited through C<Fuse::DBI>. |
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|
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=item fork |
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|
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Optional flag which forks after mount so that executing script will continue |
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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; |
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|
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# evil, evil way to solve this. It makes this module non-reentrant. But, since |
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# fuse calls another copy of this script for each mount anyway, this shouldn't |
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# be a problem. |
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my $fuse_self; |
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|
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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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|
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my $arg = shift; |
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|
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print Dumper($arg); |
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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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$self->{$_} = $arg->{$_}; |
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} |
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|
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foreach (qw(filenames read update)) { |
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carp "mount needs '$_' SQL" unless ($arg->{$_}); |
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} |
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|
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$ctime_start = time(); |
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|
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my $pid; |
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if ($arg->{'fork'}) { |
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$pid = fork(); |
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die "fork() failed: $!" unless defined $pid; |
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# child will return to caller |
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if ($pid) { |
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return $self; |
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} |
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} |
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|
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$dbh = DBI->connect($arg->{'dsn'},$arg->{'user'},$arg->{'password'}, {AutoCommit => 0, RaiseError => 1}) || die $DBI::errstr; |
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|
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$sth->{'filenames'} = $dbh->prepare($arg->{'filenames'}) || die $dbh->errstr(); |
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|
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$sth->{'read'} = $dbh->prepare($arg->{'read'}) || die $dbh->errstr(); |
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$sth->{'update'} = $dbh->prepare($arg->{'update'}) || die $dbh->errstr(); |
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|
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|
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$self->{'sth'} = $sth; |
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|
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$self->{'read_filenames'} = sub { $self->read_filenames }; |
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$self->read_filenames; |
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|
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$self->{'mounted'} = 1; |
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|
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$fuse_self = \$self; |
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|
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Fuse::main( |
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mountpoint=>$arg->{'mount'}, |
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getattr=>\&e_getattr, |
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getdir=>\&e_getdir, |
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open=>\&e_open, |
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statfs=>\&e_statfs, |
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read=>\&e_read, |
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write=>\&e_write, |
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utime=>\&e_utime, |
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truncate=>\&e_truncate, |
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unlink=>\&e_unlink, |
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rmdir=>\&e_unlink, |
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debug=>0, |
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); |
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|
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$self->{'mounted'} = 0; |
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|
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exit(0) if ($arg->{'fork'}); |
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|
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return 1; |
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|
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}; |
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|
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=head2 umount |
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|
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Unmount your database as filesystem. |
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|
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$mnt->umount; |
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|
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This will also kill background process which is translating |
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database to filesystem. |
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|
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=cut |
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|
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sub umount { |
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my $self = shift; |
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|
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if ($self->{'mounted'}) { |
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system "fusermount -u ".$self->{'mount'} || croak "umount error: $!"; |
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} |
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|
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return 1; |
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} |
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|
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$SIG{'INT'} = sub { |
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print STDERR "umount called by SIG INT\n"; |
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umount; |
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}; |
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|
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sub DESTROY { |
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my $self = shift; |
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return if (! $self->{'mounted'}); |
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print STDERR "umount called by DESTROY\n"; |
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$self->umount; |
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} |
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|
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=head2 fuse_module_loaded |
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|
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Checks if C<fuse> module is loaded in kernel. |
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|
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die "no fuse module loaded in kernel" |
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unless (Fuse::DBI::fuse_module_loaded); |
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|
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This function in called by C<mount>, but might be useful alone also. |
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|
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=cut |
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|
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sub fuse_module_loaded { |
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my $lsmod = `lsmod`; |
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die "can't start lsmod: $!" unless ($lsmod); |
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if ($lsmod =~ m/fuse/s) { |
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return 1; |
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} else { |
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return 0; |
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} |
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} |
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|
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my %files; |
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my %dirs; |
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|
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sub read_filenames { |
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my $self = shift; |
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|
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my $sth = $self->{'sth'} || die "no sth argument"; |
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|
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# create empty filesystem |
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(%files) = ( |
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'.' => { |
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type => 0040, |
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mode => 0755, |
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}, |
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# a => { |
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# cont => "File 'a'.\n", |
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# type => 0100, |
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# ctime => time()-2000 |
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# }, |
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); |
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|
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# fetch new filename list from database |
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$sth->{'filenames'}->execute() || die $sth->{'filenames'}->errstr(); |
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|
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# read them in with sesible defaults |
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while (my $row = $sth->{'filenames'}->fetchrow_hashref() ) { |
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$files{$row->{'filename'}} = { |
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size => $row->{'size'}, |
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mode => $row->{'writable'} ? 0644 : 0444, |
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id => $row->{'id'} || 99, |
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}; |
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|
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my $d; |
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foreach (split(m!/!, $row->{'filename'})) { |
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# first, entry is assumed to be file |
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if ($d) { |
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$files{$d} = { |
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size => $dirs{$d}++, |
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mode => 0755, |
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type => 0040 |
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}; |
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$files{$d.'/.'} = { |
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mode => 0755, |
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type => 0040 |
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}; |
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$files{$d.'/..'} = { |
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mode => 0755, |
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type => 0040 |
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}; |
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} |
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$d .= "/" if ($d); |
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$d .= "$_"; |
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} |
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} |
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|
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print "found ",scalar(keys %files)-scalar(keys %dirs)," files, ",scalar(keys %dirs), " dirs\n"; |
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} |
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|
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|
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sub filename_fixup { |
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my ($file) = shift; |
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$file =~ s,^/,,; |
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$file = '.' unless length($file); |
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return $file; |
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} |
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|
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sub e_getattr { |
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my ($file) = filename_fixup(shift); |
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$file =~ s,^/,,; |
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$file = '.' unless length($file); |
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return -ENOENT() unless exists($files{$file}); |
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my ($size) = $files{$file}{size} || 1; |
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my ($dev, $ino, $rdev, $blocks, $gid, $uid, $nlink, $blksize) = (0,0,0,1,0,0,1,1024); |
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my ($atime, $ctime, $mtime); |
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$atime = $ctime = $mtime = $files{$file}{ctime} || $ctime_start; |
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|
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my ($modes) = (($files{$file}{type} || 0100)<<9) + $files{$file}{mode}; |
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|
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# 2 possible types of return values: |
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#return -ENOENT(); # or any other error you care to |
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#print(join(",",($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks)),"\n"); |
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return ($dev,$ino,$modes,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks); |
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} |
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|
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sub e_getdir { |
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my ($dirname) = shift; |
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$dirname =~ s!^/!!; |
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# return as many text filenames as you like, followed by the retval. |
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print((scalar keys %files)." files total\n"); |
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my %out; |
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foreach my $f (sort keys %files) { |
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if ($dirname) { |
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if ($f =~ s/^\E$dirname\Q\///) { |
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$out{$f}++ if ($f =~ /^[^\/]+$/); |
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} |
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} else { |
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$out{$f}++ if ($f =~ /^[^\/]+$/); |
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} |
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} |
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if (! %out) { |
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$out{'no files? bug?'}++; |
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} |
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print scalar keys %out," files in dir '$dirname'\n"; |
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print "## ",join(" ",keys %out),"\n"; |
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return (keys %out),0; |
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} |
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|
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sub read_content { |
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my ($file,$id) = @_; |
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|
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die "read_content needs file and id" unless ($file && $id); |
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|
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$sth->{'read'}->execute($id) || die $sth->{'read'}->errstr; |
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$files{$file}{cont} = $sth->{'read'}->fetchrow_array; |
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$files{$file}{ctime} = time(); |
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print "file '$file' content [",length($files{$file}{cont})," bytes] read in cache\n"; |
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} |
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|
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|
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sub e_open { |
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# VFS sanity check; it keeps all the necessary state, not much to do here. |
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my $file = filename_fixup(shift); |
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my $flags = shift; |
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|
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return -ENOENT() unless exists($files{$file}); |
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return -EISDIR() unless exists($files{$file}{id}); |
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|
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read_content($file,$files{$file}{id}) unless exists($files{$file}{cont}); |
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|
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print "open '$file' ",length($files{$file}{cont})," bytes\n"; |
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return 0; |
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} |
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|
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sub e_read { |
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# return an error numeric, or binary/text string. |
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# (note: 0 means EOF, "0" will give a byte (ascii "0") |
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# to the reading program) |
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my ($file) = filename_fixup(shift); |
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my ($buf_len,$off) = @_; |
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|
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return -ENOENT() unless exists($files{$file}); |
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|
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my $len = length($files{$file}{cont}); |
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|
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print "read '$file' [$len bytes] offset $off length $buf_len\n"; |
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|
399 |
return -EINVAL() if ($off > $len); |
400 |
return 0 if ($off == $len); |
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|
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$buf_len = $len-$off if ($len - $off < $buf_len); |
403 |
|
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return substr($files{$file}{cont},$off,$buf_len); |
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} |
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|
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sub clear_cont { |
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print "transaction rollback\n"; |
409 |
$dbh->rollback || die $dbh->errstr; |
410 |
print "invalidate all cached content\n"; |
411 |
foreach my $f (keys %files) { |
412 |
delete $files{$f}{cont}; |
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} |
414 |
print "begin new transaction\n"; |
415 |
#$dbh->begin_work || die $dbh->errstr; |
416 |
} |
417 |
|
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|
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sub update_db { |
420 |
my $file = shift || die; |
421 |
|
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$files{$file}{ctime} = time(); |
423 |
|
424 |
my ($cont,$id) = ( |
425 |
$files{$file}{cont}, |
426 |
$files{$file}{id} |
427 |
); |
428 |
|
429 |
if (!$sth->{'update'}->execute($cont,$id)) { |
430 |
print "update problem: ",$sth->{'update'}->errstr; |
431 |
clear_cont; |
432 |
return 0; |
433 |
} else { |
434 |
if (! $dbh->commit) { |
435 |
print "ERROR: commit problem: ",$sth->{'update'}->errstr; |
436 |
clear_cont; |
437 |
return 0; |
438 |
} |
439 |
print "updated '$file' [",$files{$file}{id},"]\n"; |
440 |
|
441 |
$$fuse_self->{'invalidate'}->() if (ref $$fuse_self->{'invalidate'}); |
442 |
} |
443 |
return 1; |
444 |
} |
445 |
|
446 |
sub e_write { |
447 |
my $file = filename_fixup(shift); |
448 |
my ($buffer,$off) = @_; |
449 |
|
450 |
return -ENOENT() unless exists($files{$file}); |
451 |
|
452 |
my $cont = $files{$file}{cont}; |
453 |
my $len = length($cont); |
454 |
|
455 |
print "write '$file' [$len bytes] offset $off length ",length($buffer),"\n"; |
456 |
|
457 |
$files{$file}{cont} = ""; |
458 |
|
459 |
$files{$file}{cont} .= substr($cont,0,$off) if ($off > 0); |
460 |
$files{$file}{cont} .= $buffer; |
461 |
$files{$file}{cont} .= substr($cont,$off+length($buffer),$len-$off-length($buffer)) if ($off+length($buffer) < $len); |
462 |
|
463 |
$files{$file}{size} = length($files{$file}{cont}); |
464 |
|
465 |
if (! update_db($file)) { |
466 |
return -ENOSYS(); |
467 |
} else { |
468 |
return length($buffer); |
469 |
} |
470 |
} |
471 |
|
472 |
sub e_truncate { |
473 |
my $file = filename_fixup(shift); |
474 |
my $size = shift; |
475 |
|
476 |
print "truncate to $size\n"; |
477 |
|
478 |
$files{$file}{cont} = substr($files{$file}{cont},0,$size); |
479 |
$files{$file}{size} = $size; |
480 |
return 0 |
481 |
}; |
482 |
|
483 |
|
484 |
sub e_utime { |
485 |
my ($atime,$mtime,$file) = @_; |
486 |
$file = filename_fixup($file); |
487 |
|
488 |
return -ENOENT() unless exists($files{$file}); |
489 |
|
490 |
print "utime '$file' $atime $mtime\n"; |
491 |
|
492 |
$files{$file}{time} = $mtime; |
493 |
return 0; |
494 |
} |
495 |
|
496 |
sub e_statfs { return 255, 1, 1, 1, 1, 2 } |
497 |
|
498 |
sub e_unlink { |
499 |
my $file = filename_fixup(shift); |
500 |
|
501 |
if (exists( $dirs{$file} )) { |
502 |
print "unlink '$file' will re-read template names\n"; |
503 |
print Dumper($fuse_self); |
504 |
$$fuse_self->{'read_filenames'}->(); |
505 |
return 0; |
506 |
} elsif (exists( $files{$file} )) { |
507 |
print "unlink '$file' will invalidate cache\n"; |
508 |
read_content($file,$files{$file}{id}); |
509 |
return 0; |
510 |
} |
511 |
|
512 |
return -ENOENT(); |
513 |
} |
514 |
1; |
515 |
__END__ |
516 |
|
517 |
=head1 EXPORT |
518 |
|
519 |
Nothing. |
520 |
|
521 |
=head1 SEE ALSO |
522 |
|
523 |
C<FUSE (Filesystem in USErspace)> website |
524 |
L<http://sourceforge.net/projects/avf> |
525 |
|
526 |
Example for WebGUI which comes with this distribution in |
527 |
directory C<examples/webgui.pl>. It also contains a lot of documentation |
528 |
about design of this module, usage and limitations. |
529 |
|
530 |
=head1 AUTHOR |
531 |
|
532 |
Dobrica Pavlinusic, E<lt>dpavlin@rot13.orgE<gt> |
533 |
|
534 |
=head1 COPYRIGHT AND LICENSE |
535 |
|
536 |
Copyright (C) 2004 by Dobrica Pavlinusic |
537 |
|
538 |
This library is free software; you can redistribute it and/or modify |
539 |
it under the same terms as Perl itself, either Perl version 5.8.4 or, |
540 |
at your option, any later version of Perl 5 you may have available. |
541 |
|
542 |
|
543 |
=cut |
544 |
|