File Coverage

blib/lib/Image/ExifTool/Fixup.pm

Criterion	Covered	Total	%
statement	127	160	79.3
branch	42	70	60.0
condition	11	12	91.6
subroutine	10	12	83.3
pod	0	9	0.0
total	190	263	72.2

#------------------------------------------------------------------------------
# File:         Fixup.pm
#
# Description:  Utility to handle pointer fixups
#
# Revisions:    01/19/2005 - P. Harvey Created
#               04/11/2005 - P. Harvey Allow fixups to be tagged with a marker,
#                            and add new marker-related routines
#               06/21/2006 - P. Harvey Patch to work with negative offsets
#               07/07/2006 - P. Harvey Added support for 16-bit pointers
#               02/19/2013 - P. Harvey Added IsEmpty()
#
# Data Members:
#
#   Start     - Position in data where a zero pointer points to.
#   Shift     - Amount to shift offsets (relative to Start).
#   Fixups    - List of Fixup object references to to shift relative to this Fixup.
#   Pointers  - Hash of references to fixup pointer arrays, keyed by ByteOrder
#               string (with "2" added if pointer is 16-bit [default is 32-bit],
#               plus "_$marker" suffix if tagged with a marker name).
#
# Procedure:
#
#            1. Create a Fixup object for each data block containing pointers
#            2. Call AddFixup with the offset of each pointer in the block
#               - pointer is assumed int32u with the current byte order
#               - may also be called with a fixup reference for contained blocks
#            3. Add the necessary pointer offset to $$fixup{Shift}
#            4. Add data size to $$fixup{Start} if data is added before the block
#               - automatically also shifts pointers by this amount
#            5. Call ApplyFixup to apply the fixup to all pointers
#               - resets Shift and Start to 0 after applying fixup
#------------------------------------------------------------------------------

package Image::ExifTool::Fixup;

use strict;
use Image::ExifTool qw(GetByteOrder SetByteOrder Get32u Get32s Set32u
                       Get16u Get16s Set16u);
use vars qw($VERSION);

$VERSION = '1.05';

sub AddFixup($$;$$);
sub ApplyFixup($$);
sub Dump($;$);

#------------------------------------------------------------------------------
# New - create new Fixup object
# Inputs: 0) reference to Fixup object or Fixup class name
sub new
{
    local $_;
    my $that = shift;
    my $class = ref($that) || $that || 'Image::ExifTool::Fixup';
    my $self = bless {}, $class;

    # initialize required members
    $self->{Start} = 0;
    $self->{Shift} = 0;

    return $self;
}

#------------------------------------------------------------------------------
# Clone this object
# Inputs: 0) reference to Fixup object or Fixup class name
# Returns: reference to new Fixup object
sub Clone($)
{
    my $self = shift;
    my $clone = new Image::ExifTool::Fixup;
    $clone->{Start} = $self->{Start};
    $clone->{Shift} = $self->{Shift};
    my $phash = $self->{Pointers};
    if ($phash) {
        $clone->{Pointers} = { };
        my $byteOrder;
        foreach $byteOrder (keys %$phash) {
            my @pointers = @{$phash->{$byteOrder}};
            $clone->{Pointers}->{$byteOrder} = \@pointers;
        }
    }
    if ($self->{Fixups}) {
        $clone->{Fixups} = [ ];
        my $subFixup;
        foreach $subFixup (@{$self->{Fixups}}) {
            push @{$clone->{Fixups}}, $subFixup->Clone();
        }
    }
    return $clone;
}

#------------------------------------------------------------------------------
# Add fixup pointer or another fixup object below this one
# Inputs: 0) Fixup object reference
#         1) Scalar for pointer offset, or reference to Fixup object
#         2) Optional marker name for the pointer
#         3) Optional pointer format ('int16u' or 'int32u', defaults to 'int32u')
# Notes: Byte ordering must be set properly for the pointer being added (must keep
# track of the byte order of each offset since MakerNotes may have different byte order!)
sub AddFixup($$;$$)
{
    my ($self, $pointer, $marker, $format) = @_;
    if (ref $pointer) {
        $self->{Fixups} or $self->{Fixups} = [ ];
        push @{$self->{Fixups}}, $pointer;
    } else {
        my $byteOrder = GetByteOrder();
        if (defined $format) {
            if ($format eq 'int16u') {
                $byteOrder .= '2';
            } elsif ($format ne 'int32u') {
                warn "Bad Fixup pointer format $format\n";
            }
        }
        $byteOrder .= "_$marker" if defined $marker;
        my $phash = $self->{Pointers};
        $phash or $phash = $self->{Pointers} = { };
        $phash->{$byteOrder} or $phash->{$byteOrder} = [ ];
        push @{$phash->{$byteOrder}}, $pointer;
    }
}

#------------------------------------------------------------------------------
# fix up pointer offsets
# Inputs: 0) Fixup object reference, 1) data reference
# Outputs: Collapses fixup hierarchy into linear lists of fixup pointers
sub ApplyFixup($$)
{
    my ($self, $dataPt) = @_;

    my $start = $self->{Start};
    my $shift = $self->{Shift} + $start;   # make shift relative to start
    my $phash = $self->{Pointers};

    # fix up pointers in this fixup
    if ($phash and ($start or $shift)) {
        my $saveOrder = GetByteOrder(); # save original byte ordering
        my ($byteOrder, $ptr);
        foreach $byteOrder (keys %$phash) {
            SetByteOrder(substr($byteOrder,0,2));
            # apply the fixup offset shift (must get as signed integer
            # to avoid overflow in case it was negative before)
            my ($get, $set) = ($byteOrder =~ /^(II2|MM2)/) ?
                              (\&Get16s, \&Set16u) : (\&Get32s, \&Set32u);
            foreach $ptr (@{$phash->{$byteOrder}}) {
                $ptr += $start;         # update pointer to new start location
                next unless $shift;
                &$set(&$get($dataPt, $ptr) + $shift, $dataPt, $ptr);
            }
        }
        SetByteOrder($saveOrder);       # restore original byte ordering
    }
    # recurse into contained fixups
    if ($self->{Fixups}) {
        # create our pointer hash if it doesn't exist
        $phash or $phash = $self->{Pointers} = { };
        # loop through all contained fixups
        my $subFixup;
        foreach $subFixup (@{$self->{Fixups}}) {
            # adjust the subfixup start and shift
            $subFixup->{Start} += $start;
            $subFixup->{Shift} += $shift - $start;
            # recursively apply contained fixups
            ApplyFixup($subFixup, $dataPt);
            my $shash = $subFixup->{Pointers} or next;
            # add all pointers to our collapsed lists
            my $byteOrder;
            foreach $byteOrder (keys %$shash) {
                $phash->{$byteOrder} or $phash->{$byteOrder} = [ ];
                push @{$phash->{$byteOrder}}, @{$shash->{$byteOrder}};
                delete $shash->{$byteOrder};
            }
            delete $subFixup->{Pointers};
        }
        delete $self->{Fixups};    # remove our contained fixups
    }
    # reset our Start/Shift for the collapsed fixup
    $self->{Start} = $self->{Shift} = 0;
}

#------------------------------------------------------------------------------
# Is this Fixup empty?
# Inputs: 0) Fixup object ref
# Returns: True if there are no offsets to fix
sub IsEmpty($)
{
    my $self = shift;
    my $phash = $self->{Pointers};
    if ($phash) {
        my $key;
        foreach $key (keys %$phash) {
            next unless ref $$phash{$key} eq 'ARRAY';
            return 0 if @{$$phash{$key}};
        }
    }
    return 1;
}

#------------------------------------------------------------------------------
# Does specified marker exist?
# Inputs: 0) Fixup object reference, 1) marker name
# Returns: True if fixup contains specified marker name
sub HasMarker($$)
{
    my ($self, $marker) = @_;
    my $phash = $self->{Pointers};
    return 0 unless $phash;
    return 1 if grep /_$marker$/, keys %$phash;
    return 0 unless $self->{Fixups};
    my $subFixup;
    foreach $subFixup (@{$self->{Fixups}}) {
        return 1 if $subFixup->HasMarker($marker);
    }
    return 0;
}

#------------------------------------------------------------------------------
# Set all marker pointers to specified value
# Inputs: 0) Fixup object reference, 1) data reference
#         2) marker name, 3) pointer value, 4) offset to start of data
sub SetMarkerPointers($$$$;$)
{
    my ($self, $dataPt, $marker, $value, $startOffset) = @_;
    my $start = $self->{Start} + ($startOffset || 0);
    my $phash = $self->{Pointers};

    if ($phash) {
        my $saveOrder = GetByteOrder(); # save original byte ordering
        my ($byteOrder, $ptr);
        foreach $byteOrder (keys %$phash) {
            next unless $byteOrder =~ /^(II|MM)(2?)_$marker$/;
            SetByteOrder($1);
            my $set = $2 ? \&Set16u : \&Set32u;
            foreach $ptr (@{$phash->{$byteOrder}}) {
                &$set($value, $dataPt, $ptr + $start);
            }
        }
        SetByteOrder($saveOrder);       # restore original byte ordering
    }
    if ($self->{Fixups}) {
        my $subFixup;
        foreach $subFixup (@{$self->{Fixups}}) {
            $subFixup->SetMarkerPointers($dataPt, $marker, $value, $start);
        }
    }
}

#------------------------------------------------------------------------------
# Get pointer values for specified marker
# Inputs: 0) Fixup object reference, 1) data reference,
#         2) marker name, 3) offset to start of data
# Returns: List of marker pointers in list context, or first marker pointer otherwise
sub GetMarkerPointers($$$;$)
{
    my ($self, $dataPt, $marker, $startOffset) = @_;
    my $start = $self->{Start} + ($startOffset || 0);
    my $phash = $self->{Pointers};
    my @pointers;

    if ($phash) {
        my $saveOrder = GetByteOrder();
        my ($byteOrder, $ptr);
        foreach $byteOrder (grep /_$marker$/, keys %$phash) {
            SetByteOrder(substr($byteOrder,0,2));
            my $get = ($byteOrder =~ /^(II2|MM2)/) ? \&Get16u : \&Get32u;
            foreach $ptr (@{$phash->{$byteOrder}}) {
                push @pointers, &$get($dataPt, $ptr + $start);
            }
        }
        SetByteOrder($saveOrder);       # restore original byte ordering
    }
    if ($self->{Fixups}) {
        my $subFixup;
        foreach $subFixup (@{$self->{Fixups}}) {
            push @pointers, $subFixup->GetMarkerPointers($dataPt, $marker, $start);
        }
    }
    return @pointers if wantarray;
    return $pointers[0];
}

#------------------------------------------------------------------------------
# Dump fixup to console for debugging
# Inputs: 0) Fixup object reference, 1) optional initial indent string
sub Dump($;$)
{
    my ($self, $indent) = @_;
    $indent or $indent = '';
    printf "${indent}Fixup start=0x%x shift=0x%x\n", $self->{Start}, $self->{Shift};
    my $phash = $self->{Pointers};
    if ($phash) {
        my $byteOrder;
        foreach $byteOrder (sort keys %$phash) {
            print "$indent  $byteOrder: ", join(' ',@{$phash->{$byteOrder}}),"\n";
        }
    }
    if ($self->{Fixups}) {
        my $subFixup;
        foreach $subFixup (@{$self->{Fixups}}) {
            Dump($subFixup, $indent . '  ');
        }
    }
}


1; # end

__END__