# Filesys::POSIX           Copyright (c) 2011 cPanel, Inc.  All rights reserved.
# copyright@cpanel.net                                        http://cpanel.net/
# 
# Written by Erin Schönhals <erin@cpanel.net>.  Released under the terms of the
# Perl Artistic License.
package Filesys::POSIX::VFS;
use strict;
use warnings;
use Filesys::POSIX::Bits;
use Filesys::POSIX::Path       ();
use Filesys::POSIX::VFS::Inode ();
use Carp qw/confess/;
sub new {
    return bless {
        'mounts'  => [],
        'devices' => {},
        'vnodes'  => {}
      },
      shift;
}
sub statfs {
    my ( $self, $start, %opts ) = @_;
    my $inode = $start;
    my $ret;
    while ( $inode->{'vnode'} ) {
        $inode = $inode->{'vnode'};
    }
    if ( $opts{'exact'} ) {
        $ret = $self->{'vnodes'}->{$inode};
    }
    else {
        $ret = $self->{'devices'}->{ $inode->{'dev'} };
    }
    unless ($ret) {
        confess('Not mounted') unless $opts{'silent'};
    }
    return $ret;
}
sub mountlist {
    my ($self) = @_;
    return @{ $self->{'mounts'} };
}
#
# It should be noted that any usage of pathnames in this module are entirely
# symbolic and are not used for canonical purposes.  The higher-level
# filesystem layer should take on the responsibility of providing both the
# canonically-correct absolute pathnames for mount points, and helping locate
# the appropriate VFS mount point for querying purposes.
#
sub mount {
    my ( $self, $dev, $path, $mountpoint, %data ) = @_;
    if ( grep { $_->{'dev'} eq $dev } @{ $self->{'mounts'} } ) {
        confess('Already mounted');
    }
    $data{'special'} ||= scalar $dev;
    #
    # Generate a generic BSD-style filesystem type string.
    #
    my $type = lc ref $dev;
    $type =~ s/^([a-z_][a-z0-9_]*::)*//;
    #
    # Create a vnode record munged from the mountpoint and new
    # filesystem root.
    #
    my $vnode = Filesys::POSIX::VFS::Inode->new( $mountpoint, $dev->{'root'} );
    #
    # Associate the mountpoint and filesystem roots with this vnode.
    #
    $mountpoint->{'vnode'} = $vnode;
    $dev->{'root'}->{'vnode'} = $vnode;
    #
    # Generate the mount record.
    #
    my $mount = {
        'mountpoint' => $mountpoint,
        'root'       => $dev->{'root'},
        'special'    => $data{'special'},
        'dev'        => $dev,
        'type'       => $type,
        'path'       => $path,
        'vnode'      => $vnode,
        'flags' => { map { $_ => $data{$_} } grep { $_ ne 'special' } keys %data }
    };
    #
    # Store the mount record in the ordered mount list.
    #
    push @{ $self->{'mounts'} }, $mount;
    #
    # Associate the vnode with the mount rcord.
    #
    $self->{'vnodes'}->{$vnode} = $mount;
    #
    # Finally, associate the filesystem with the mount record.
    #
    $self->{'devices'}->{$dev} = $mount;
    return $self;
}
sub vnode {
    my ( $self, $start ) = @_;
    my $inode = $start;
    return undef unless $inode;
    while ( $inode->{'vnode'} ) {
        $inode = $inode->{'vnode'};
    }
    my $mount = $self->{'devices'}->{ $inode->{'dev'} };
    if ( $mount->{'flags'}->{'noexec'} ) {
        $inode->{'mode'} &= ~$S_IX;
    }
    if ( $mount->{'flags'}->{'nosuid'} ) {
        $inode->{'mode'} &= ~$S_ISUID;
    }
    foreach (qw/uid gid/) {
        if ( defined $mount->{'flags'}->{$_} ) {
            $inode->{$_} = $mount->{'flags'}->{$_};
        }
    }
    return $inode;
}
sub unmount {
    my ( $self, $mount ) = @_;
    #
    # First, check to see that the filesystem mount record found is a
    # dependency for another mounted filesystem.
    #
    foreach ( @{ $self->{'mounts'} } ) {
        next if $_ == $mount;
        confess('Device or resource busy') if $_->{'mountpoint'}->{'dev'} == $mount->{'dev'};
    }
    #
    # Pluck the filesystem from the mount list.
    #
    for ( my $i = 0; $self->{'mounts'}->[$i]; $i++ ) {
        next unless $self->{'mounts'}->[$i] eq $mount;
        splice @{ $self->{'mounts'} }, $i;
        last;
    }
    #
    # Untie the vnode reference from its original mount point and root.
    #
    delete $mount->{'mountpoint'}->{'vnode'};
    delete $mount->{'root'}->{'vnode'};
    #
    # Break references to the mount record from the per-vnode hash.
    #
    delete $self->{'vnodes'}->{ $mount->{'vnode'} };
    #
    # Kill references to the mount record from the per-device hash.
    #
    delete $self->{'devices'}->{ $mount->{'dev'} };
    return $self;
}
1;