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Diffstat (limited to '')
| -rw-r--r-- | wp-includes/class-avif-info.php | 781 |
1 files changed, 781 insertions, 0 deletions
diff --git a/wp-includes/class-avif-info.php b/wp-includes/class-avif-info.php new file mode 100644 index 0000000..93280b3 --- /dev/null +++ b/wp-includes/class-avif-info.php @@ -0,0 +1,781 @@ +<?php +/** + * Copyright (c) 2021, Alliance for Open Media. All rights reserved + * + * This source code is subject to the terms of the BSD 2 Clause License and + * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License + * was not distributed with this source code in the LICENSE file, you can + * obtain it at www.aomedia.org/license/software. If the Alliance for Open + * Media Patent License 1.0 was not distributed with this source code in the + * PATENTS file, you can obtain it at www.aomedia.org/license/patent. + * + * Note: this class is from libavifinfo - https://aomedia.googlesource.com/libavifinfo/+/refs/heads/main/avifinfo.php at f509487. + * It is used as a fallback to parse AVIF files when the server doesn't support AVIF, + * primarily to identify the width and height of the image. + * + * Note PHP 8.2 added native support for AVIF, so this class can be removed when WordPress requires PHP 8.2. + */ + +namespace Avifinfo; + +const FOUND = 0; // Input correctly parsed and information retrieved. +const NOT_FOUND = 1; // Input correctly parsed but information is missing or elsewhere. +const TRUNCATED = 2; // Input correctly parsed until missing bytes to continue. +const ABORTED = 3; // Input correctly parsed until stopped to avoid timeout or crash. +const INVALID = 4; // Input incorrectly parsed. + +const MAX_SIZE = 4294967295; // Unlikely to be insufficient to parse AVIF headers. +const MAX_NUM_BOXES = 4096; // Be reasonable. Avoid timeouts and out-of-memory. +const MAX_VALUE = 255; +const MAX_TILES = 16; +const MAX_PROPS = 32; +const MAX_FEATURES = 8; +const UNDEFINED = 0; // Value was not yet parsed. + +/** + * Reads an unsigned integer with most significant bits first. + * + * @param binary string $input Must be at least $num_bytes-long. + * @param int $num_bytes Number of parsed bytes. + * @return int Value. + */ +function read_big_endian( $input, $num_bytes ) { + if ( $num_bytes == 1 ) { + return unpack( 'C', $input ) [1]; + } else if ( $num_bytes == 2 ) { + return unpack( 'n', $input ) [1]; + } else if ( $num_bytes == 3 ) { + $bytes = unpack( 'C3', $input ); + return ( $bytes[1] << 16 ) | ( $bytes[2] << 8 ) | $bytes[3]; + } else { // $num_bytes is 4 + // This might fail to read unsigned values >= 2^31 on 32-bit systems. + // See https://www.php.net/manual/en/function.unpack.php#106041 + return unpack( 'N', $input ) [1]; + } +} + +/** + * Reads bytes and advances the stream position by the same count. + * + * @param stream $handle Bytes will be read from this resource. + * @param int $num_bytes Number of bytes read. Must be greater than 0. + * @return binary string|false The raw bytes or false on failure. + */ +function read( $handle, $num_bytes ) { + $data = fread( $handle, $num_bytes ); + return ( $data !== false && strlen( $data ) >= $num_bytes ) ? $data : false; +} + +/** + * Advances the stream position by the given offset. + * + * @param stream $handle Bytes will be skipped from this resource. + * @param int $num_bytes Number of skipped bytes. Can be 0. + * @return bool True on success or false on failure. + */ +// Skips 'num_bytes' from the 'stream'. 'num_bytes' can be zero. +function skip( $handle, $num_bytes ) { + return ( fseek( $handle, $num_bytes, SEEK_CUR ) == 0 ); +} + +//------------------------------------------------------------------------------ +// Features are parsed into temporary property associations. + +class Tile { // Tile item id <-> parent item id associations. + public $tile_item_id; + public $parent_item_id; +} + +class Prop { // Property index <-> item id associations. + public $property_index; + public $item_id; +} + +class Dim_Prop { // Property <-> features associations. + public $property_index; + public $width; + public $height; +} + +class Chan_Prop { // Property <-> features associations. + public $property_index; + public $bit_depth; + public $num_channels; +} + +class Features { + public $has_primary_item = false; // True if "pitm" was parsed. + public $has_alpha = false; // True if an alpha "auxC" was parsed. + public $primary_item_id; + public $primary_item_features = array( // Deduced from the data below. + 'width' => UNDEFINED, // In number of pixels. + 'height' => UNDEFINED, // Ignores mirror and rotation. + 'bit_depth' => UNDEFINED, // Likely 8, 10 or 12 bits per channel per pixel. + 'num_channels' => UNDEFINED // Likely 1, 2, 3 or 4 channels: + // (1 monochrome or 3 colors) + (0 or 1 alpha) + ); + + public $tiles = array(); // Tile[] + public $props = array(); // Prop[] + public $dim_props = array(); // Dim_Prop[] + public $chan_props = array(); // Chan_Prop[] + + /** + * Binds the width, height, bit depth and number of channels from stored internal features. + * + * @param int $target_item_id Id of the item whose features will be bound. + * @param int $tile_depth Maximum recursion to search within tile-parent relations. + * @return Status FOUND on success or NOT_FOUND on failure. + */ + private function get_item_features( $target_item_id, $tile_depth ) { + foreach ( $this->props as $prop ) { + if ( $prop->item_id != $target_item_id ) { + continue; + } + + // Retrieve the width and height of the primary item if not already done. + if ( $target_item_id == $this->primary_item_id && + ( $this->primary_item_features['width'] == UNDEFINED || + $this->primary_item_features['height'] == UNDEFINED ) ) { + foreach ( $this->dim_props as $dim_prop ) { + if ( $dim_prop->property_index != $prop->property_index ) { + continue; + } + $this->primary_item_features['width'] = $dim_prop->width; + $this->primary_item_features['height'] = $dim_prop->height; + if ( $this->primary_item_features['bit_depth'] != UNDEFINED && + $this->primary_item_features['num_channels'] != UNDEFINED ) { + return FOUND; + } + break; + } + } + // Retrieve the bit depth and number of channels of the target item if not + // already done. + if ( $this->primary_item_features['bit_depth'] == UNDEFINED || + $this->primary_item_features['num_channels'] == UNDEFINED ) { + foreach ( $this->chan_props as $chan_prop ) { + if ( $chan_prop->property_index != $prop->property_index ) { + continue; + } + $this->primary_item_features['bit_depth'] = $chan_prop->bit_depth; + $this->primary_item_features['num_channels'] = $chan_prop->num_channels; + if ( $this->primary_item_features['width'] != UNDEFINED && + $this->primary_item_features['height'] != UNDEFINED ) { + return FOUND; + } + break; + } + } + } + + // Check for the bit_depth and num_channels in a tile if not yet found. + if ( $tile_depth < 3 ) { + foreach ( $this->tiles as $tile ) { + if ( $tile->parent_item_id != $target_item_id ) { + continue; + } + $status = get_item_features( $tile->tile_item_id, $tile_depth + 1 ); + if ( $status != NOT_FOUND ) { + return $status; + } + } + } + return NOT_FOUND; + } + + /** + * Finds the width, height, bit depth and number of channels of the primary item. + * + * @return Status FOUND on success or NOT_FOUND on failure. + */ + public function get_primary_item_features() { + // Nothing to do without the primary item ID. + if ( !$this->has_primary_item ) { + return NOT_FOUND; + } + // Early exit. + if ( empty( $this->dim_props ) || empty( $this->chan_props ) ) { + return NOT_FOUND; + } + $status = $this->get_item_features( $this->primary_item_id, /*tile_depth=*/ 0 ); + if ( $status != FOUND ) { + return $status; + } + + // "auxC" is parsed before the "ipma" properties so it is known now, if any. + if ( $this->has_alpha ) { + ++$this->primary_item_features['num_channels']; + } + return FOUND; + } +} + +//------------------------------------------------------------------------------ + +class Box { + public $size; // In bytes. + public $type; // Four characters. + public $version; // 0 or actual version if this is a full box. + public $flags; // 0 or actual value if this is a full box. + public $content_size; // 'size' minus the header size. + + /** + * Reads the box header. + * + * @param stream $handle The resource the header will be parsed from. + * @param int $num_parsed_boxes The total number of parsed boxes. Prevents timeouts. + * @param int $num_remaining_bytes The number of bytes that should be available from the resource. + * @return Status FOUND on success or an error on failure. + */ + public function parse( $handle, &$num_parsed_boxes, $num_remaining_bytes = MAX_SIZE ) { + // See ISO/IEC 14496-12:2012(E) 4.2 + $header_size = 8; // box 32b size + 32b type (at least) + if ( $header_size > $num_remaining_bytes ) { + return INVALID; + } + if ( !( $data = read( $handle, 8 ) ) ) { + return TRUNCATED; + } + $this->size = read_big_endian( $data, 4 ); + $this->type = substr( $data, 4, 4 ); + // 'box->size==1' means 64-bit size should be read after the box type. + // 'box->size==0' means this box extends to all remaining bytes. + if ( $this->size == 1 ) { + $header_size += 8; + if ( $header_size > $num_remaining_bytes ) { + return INVALID; + } + if ( !( $data = read( $handle, 8 ) ) ) { + return TRUNCATED; + } + // Stop the parsing if any box has a size greater than 4GB. + if ( read_big_endian( $data, 4 ) != 0 ) { + return ABORTED; + } + // Read the 32 least-significant bits. + $this->size = read_big_endian( substr( $data, 4, 4 ), 4 ); + } else if ( $this->size == 0 ) { + $this->size = $num_remaining_bytes; + } + if ( $this->size < $header_size ) { + return INVALID; + } + if ( $this->size > $num_remaining_bytes ) { + return INVALID; + } + + $has_fullbox_header = $this->type == 'meta' || $this->type == 'pitm' || + $this->type == 'ipma' || $this->type == 'ispe' || + $this->type == 'pixi' || $this->type == 'iref' || + $this->type == 'auxC'; + if ( $has_fullbox_header ) { + $header_size += 4; + } + if ( $this->size < $header_size ) { + return INVALID; + } + $this->content_size = $this->size - $header_size; + // Avoid timeouts. The maximum number of parsed boxes is arbitrary. + ++$num_parsed_boxes; + if ( $num_parsed_boxes >= MAX_NUM_BOXES ) { + return ABORTED; + } + + $this->version = 0; + $this->flags = 0; + if ( $has_fullbox_header ) { + if ( !( $data = read( $handle, 4 ) ) ) { + return TRUNCATED; + } + $this->version = read_big_endian( $data, 1 ); + $this->flags = read_big_endian( substr( $data, 1, 3 ), 3 ); + // See AV1 Image File Format (AVIF) 8.1 + // at https://aomediacodec.github.io/av1-avif/#avif-boxes (available when + // https://github.com/AOMediaCodec/av1-avif/pull/170 is merged). + $is_parsable = ( $this->type == 'meta' && $this->version <= 0 ) || + ( $this->type == 'pitm' && $this->version <= 1 ) || + ( $this->type == 'ipma' && $this->version <= 1 ) || + ( $this->type == 'ispe' && $this->version <= 0 ) || + ( $this->type == 'pixi' && $this->version <= 0 ) || + ( $this->type == 'iref' && $this->version <= 1 ) || + ( $this->type == 'auxC' && $this->version <= 0 ); + // Instead of considering this file as invalid, skip unparsable boxes. + if ( !$is_parsable ) { + $this->type = 'unknownversion'; + } + } + // print_r( $this ); // Uncomment to print all boxes. + return FOUND; + } +} + +//------------------------------------------------------------------------------ + +class Parser { + private $handle; // Input stream. + private $num_parsed_boxes = 0; + private $data_was_skipped = false; + public $features; + + function __construct( $handle ) { + $this->handle = $handle; + $this->features = new Features(); + } + + /** + * Parses an "ipco" box. + * + * "ispe" is used for width and height, "pixi" and "av1C" are used for bit depth + * and number of channels, and "auxC" is used for alpha. + * + * @param stream $handle The resource the box will be parsed from. + * @param int $num_remaining_bytes The number of bytes that should be available from the resource. + * @return Status FOUND on success or an error on failure. + */ + private function parse_ipco( $num_remaining_bytes ) { + $box_index = 1; // 1-based index. Used for iterating over properties. + do { + $box = new Box(); + $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); + if ( $status != FOUND ) { + return $status; + } + + if ( $box->type == 'ispe' ) { + // See ISO/IEC 23008-12:2017(E) 6.5.3.2 + if ( $box->content_size < 8 ) { + return INVALID; + } + if ( !( $data = read( $this->handle, 8 ) ) ) { + return TRUNCATED; + } + $width = read_big_endian( substr( $data, 0, 4 ), 4 ); + $height = read_big_endian( substr( $data, 4, 4 ), 4 ); + if ( $width == 0 || $height == 0 ) { + return INVALID; + } + if ( count( $this->features->dim_props ) <= MAX_FEATURES && + $box_index <= MAX_VALUE ) { + $dim_prop_count = count( $this->features->dim_props ); + $this->features->dim_props[$dim_prop_count] = new Dim_Prop(); + $this->features->dim_props[$dim_prop_count]->property_index = $box_index; + $this->features->dim_props[$dim_prop_count]->width = $width; + $this->features->dim_props[$dim_prop_count]->height = $height; + } else { + $this->data_was_skipped = true; + } + if ( !skip( $this->handle, $box->content_size - 8 ) ) { + return TRUNCATED; + } + } else if ( $box->type == 'pixi' ) { + // See ISO/IEC 23008-12:2017(E) 6.5.6.2 + if ( $box->content_size < 1 ) { + return INVALID; + } + if ( !( $data = read( $this->handle, 1 ) ) ) { + return TRUNCATED; + } + $num_channels = read_big_endian( $data, 1 ); + if ( $num_channels < 1 ) { + return INVALID; + } + if ( $box->content_size < 1 + $num_channels ) { + return INVALID; + } + if ( !( $data = read( $this->handle, 1 ) ) ) { + return TRUNCATED; + } + $bit_depth = read_big_endian( $data, 1 ); + if ( $bit_depth < 1 ) { + return INVALID; + } + for ( $i = 1; $i < $num_channels; ++$i ) { + if ( !( $data = read( $this->handle, 1 ) ) ) { + return TRUNCATED; + } + // Bit depth should be the same for all channels. + if ( read_big_endian( $data, 1 ) != $bit_depth ) { + return INVALID; + } + if ( $i > 32 ) { + return ABORTED; // Be reasonable. + } + } + if ( count( $this->features->chan_props ) <= MAX_FEATURES && + $box_index <= MAX_VALUE && $bit_depth <= MAX_VALUE && + $num_channels <= MAX_VALUE ) { + $chan_prop_count = count( $this->features->chan_props ); + $this->features->chan_props[$chan_prop_count] = new Chan_Prop(); + $this->features->chan_props[$chan_prop_count]->property_index = $box_index; + $this->features->chan_props[$chan_prop_count]->bit_depth = $bit_depth; + $this->features->chan_props[$chan_prop_count]->num_channels = $num_channels; + } else { + $this->data_was_skipped = true; + } + if ( !skip( $this->handle, $box->content_size - ( 1 + $num_channels ) ) ) { + return TRUNCATED; + } + } else if ( $box->type == 'av1C' ) { + // See AV1 Codec ISO Media File Format Binding 2.3.1 + // at https://aomediacodec.github.io/av1-isobmff/#av1c + // Only parse the necessary third byte. Assume that the others are valid. + if ( $box->content_size < 3 ) { + return INVALID; + } + if ( !( $data = read( $this->handle, 3 ) ) ) { + return TRUNCATED; + } + $byte = read_big_endian( substr( $data, 2, 1 ), 1 ); + $high_bitdepth = ( $byte & 0x40 ) != 0; + $twelve_bit = ( $byte & 0x20 ) != 0; + $monochrome = ( $byte & 0x10 ) != 0; + if ( $twelve_bit && !$high_bitdepth ) { + return INVALID; + } + if ( count( $this->features->chan_props ) <= MAX_FEATURES && + $box_index <= MAX_VALUE ) { + $chan_prop_count = count( $this->features->chan_props ); + $this->features->chan_props[$chan_prop_count] = new Chan_Prop(); + $this->features->chan_props[$chan_prop_count]->property_index = $box_index; + $this->features->chan_props[$chan_prop_count]->bit_depth = + $high_bitdepth ? $twelve_bit ? 12 : 10 : 8; + $this->features->chan_props[$chan_prop_count]->num_channels = $monochrome ? 1 : 3; + } else { + $this->data_was_skipped = true; + } + if ( !skip( $this->handle, $box->content_size - 3 ) ) { + return TRUNCATED; + } + } else if ( $box->type == 'auxC' ) { + // See AV1 Image File Format (AVIF) 4 + // at https://aomediacodec.github.io/av1-avif/#auxiliary-images + $kAlphaStr = "urn:mpeg:mpegB:cicp:systems:auxiliary:alpha\0"; + $kAlphaStrLength = 44; // Includes terminating character. + if ( $box->content_size >= $kAlphaStrLength ) { + if ( !( $data = read( $this->handle, $kAlphaStrLength ) ) ) { + return TRUNCATED; + } + if ( substr( $data, 0, $kAlphaStrLength ) == $kAlphaStr ) { + // Note: It is unlikely but it is possible that this alpha plane does + // not belong to the primary item or a tile. Ignore this issue. + $this->features->has_alpha = true; + } + if ( !skip( $this->handle, $box->content_size - $kAlphaStrLength ) ) { + return TRUNCATED; + } + } else { + if ( !skip( $this->handle, $box->content_size ) ) { + return TRUNCATED; + } + } + } else { + if ( !skip( $this->handle, $box->content_size ) ) { + return TRUNCATED; + } + } + ++$box_index; + $num_remaining_bytes -= $box->size; + } while ( $num_remaining_bytes > 0 ); + return NOT_FOUND; + } + + /** + * Parses an "iprp" box. + * + * The "ipco" box contain the properties which are linked to items by the "ipma" box. + * + * @param stream $handle The resource the box will be parsed from. + * @param int $num_remaining_bytes The number of bytes that should be available from the resource. + * @return Status FOUND on success or an error on failure. + */ + private function parse_iprp( $num_remaining_bytes ) { + do { + $box = new Box(); + $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); + if ( $status != FOUND ) { + return $status; + } + + if ( $box->type == 'ipco' ) { + $status = $this->parse_ipco( $box->content_size ); + if ( $status != NOT_FOUND ) { + return $status; + } + } else if ( $box->type == 'ipma' ) { + // See ISO/IEC 23008-12:2017(E) 9.3.2 + $num_read_bytes = 4; + if ( $box->content_size < $num_read_bytes ) { + return INVALID; + } + if ( !( $data = read( $this->handle, $num_read_bytes ) ) ) { + return TRUNCATED; + } + $entry_count = read_big_endian( $data, 4 ); + $id_num_bytes = ( $box->version < 1 ) ? 2 : 4; + $index_num_bytes = ( $box->flags & 1 ) ? 2 : 1; + $essential_bit_mask = ( $box->flags & 1 ) ? 0x8000 : 0x80; + + for ( $entry = 0; $entry < $entry_count; ++$entry ) { + if ( $entry >= MAX_PROPS || + count( $this->features->props ) >= MAX_PROPS ) { + $this->data_was_skipped = true; + break; + } + $num_read_bytes += $id_num_bytes + 1; + if ( $box->content_size < $num_read_bytes ) { + return INVALID; + } + if ( !( $data = read( $this->handle, $id_num_bytes + 1 ) ) ) { + return TRUNCATED; + } + $item_id = read_big_endian( + substr( $data, 0, $id_num_bytes ), $id_num_bytes ); + $association_count = read_big_endian( + substr( $data, $id_num_bytes, 1 ), 1 ); + + for ( $property = 0; $property < $association_count; ++$property ) { + if ( $property >= MAX_PROPS || + count( $this->features->props ) >= MAX_PROPS ) { + $this->data_was_skipped = true; + break; + } + $num_read_bytes += $index_num_bytes; + if ( $box->content_size < $num_read_bytes ) { + return INVALID; + } + if ( !( $data = read( $this->handle, $index_num_bytes ) ) ) { + return TRUNCATED; + } + $value = read_big_endian( $data, $index_num_bytes ); + // $essential = ($value & $essential_bit_mask); // Unused. + $property_index = ( $value & ~$essential_bit_mask ); + if ( $property_index <= MAX_VALUE && $item_id <= MAX_VALUE ) { + $prop_count = count( $this->features->props ); + $this->features->props[$prop_count] = new Prop(); + $this->features->props[$prop_count]->property_index = $property_index; + $this->features->props[$prop_count]->item_id = $item_id; + } else { + $this->data_was_skipped = true; + } + } + if ( $property < $association_count ) { + break; // Do not read garbage. + } + } + + // If all features are available now, do not look further. + $status = $this->features->get_primary_item_features(); + if ( $status != NOT_FOUND ) { + return $status; + } + + // Mostly if 'data_was_skipped'. + if ( !skip( $this->handle, $box->content_size - $num_read_bytes ) ) { + return TRUNCATED; + } + } else { + if ( !skip( $this->handle, $box->content_size ) ) { + return TRUNCATED; + } + } + $num_remaining_bytes -= $box->size; + } while ( $num_remaining_bytes > 0 ); + return NOT_FOUND; + } + + /** + * Parses an "iref" box. + * + * The "dimg" boxes contain links between tiles and their parent items, which + * can be used to infer bit depth and number of channels for the primary item + * when the latter does not have these properties. + * + * @param stream $handle The resource the box will be parsed from. + * @param int $num_remaining_bytes The number of bytes that should be available from the resource. + * @return Status FOUND on success or an error on failure. + */ + private function parse_iref( $num_remaining_bytes ) { + do { + $box = new Box(); + $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); + if ( $status != FOUND ) { + return $status; + } + + if ( $box->type == 'dimg' ) { + // See ISO/IEC 14496-12:2015(E) 8.11.12.2 + $num_bytes_per_id = ( $box->version == 0 ) ? 2 : 4; + $num_read_bytes = $num_bytes_per_id + 2; + if ( $box->content_size < $num_read_bytes ) { + return INVALID; + } + if ( !( $data = read( $this->handle, $num_read_bytes ) ) ) { + return TRUNCATED; + } + $from_item_id = read_big_endian( $data, $num_bytes_per_id ); + $reference_count = read_big_endian( substr( $data, $num_bytes_per_id, 2 ), 2 ); + + for ( $i = 0; $i < $reference_count; ++$i ) { + if ( $i >= MAX_TILES ) { + $this->data_was_skipped = true; + break; + } + $num_read_bytes += $num_bytes_per_id; + if ( $box->content_size < $num_read_bytes ) { + return INVALID; + } + if ( !( $data = read( $this->handle, $num_bytes_per_id ) ) ) { + return TRUNCATED; + } + $to_item_id = read_big_endian( $data, $num_bytes_per_id ); + $tile_count = count( $this->features->tiles ); + if ( $from_item_id <= MAX_VALUE && $to_item_id <= MAX_VALUE && + $tile_count < MAX_TILES ) { + $this->features->tiles[$tile_count] = new Tile(); + $this->features->tiles[$tile_count]->tile_item_id = $to_item_id; + $this->features->tiles[$tile_count]->parent_item_id = $from_item_id; + } else { + $this->data_was_skipped = true; + } + } + + // If all features are available now, do not look further. + $status = $this->features->get_primary_item_features(); + if ( $status != NOT_FOUND ) { + return $status; + } + + // Mostly if 'data_was_skipped'. + if ( !skip( $this->handle, $box->content_size - $num_read_bytes ) ) { + return TRUNCATED; + } + } else { + if ( !skip( $this->handle, $box->content_size ) ) { + return TRUNCATED; + } + } + $num_remaining_bytes -= $box->size; + } while ( $num_remaining_bytes > 0 ); + return NOT_FOUND; + } + + /** + * Parses a "meta" box. + * + * It looks for the primary item ID in the "pitm" box and recurses into other boxes + * to find its features. + * + * @param stream $handle The resource the box will be parsed from. + * @param int $num_remaining_bytes The number of bytes that should be available from the resource. + * @return Status FOUND on success or an error on failure. + */ + private function parse_meta( $num_remaining_bytes ) { + do { + $box = new Box(); + $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes ); + if ( $status != FOUND ) { + return $status; + } + + if ( $box->type == 'pitm' ) { + // See ISO/IEC 14496-12:2015(E) 8.11.4.2 + $num_bytes_per_id = ( $box->version == 0 ) ? 2 : 4; + if ( $num_bytes_per_id > $num_remaining_bytes ) { + return INVALID; + } + if ( !( $data = read( $this->handle, $num_bytes_per_id ) ) ) { + return TRUNCATED; + } + $primary_item_id = read_big_endian( $data, $num_bytes_per_id ); + if ( $primary_item_id > MAX_VALUE ) { + return ABORTED; + } + $this->features->has_primary_item = true; + $this->features->primary_item_id = $primary_item_id; + if ( !skip( $this->handle, $box->content_size - $num_bytes_per_id ) ) { + return TRUNCATED; + } + } else if ( $box->type == 'iprp' ) { + $status = $this->parse_iprp( $box->content_size ); + if ( $status != NOT_FOUND ) { + return $status; + } + } else if ( $box->type == 'iref' ) { + $status = $this->parse_iref( $box->content_size ); + if ( $status != NOT_FOUND ) { + return $status; + } + } else { + if ( !skip( $this->handle, $box->content_size ) ) { + return TRUNCATED; + } + } + $num_remaining_bytes -= $box->size; + } while ( $num_remaining_bytes != 0 ); + // According to ISO/IEC 14496-12:2012(E) 8.11.1.1 there is at most one "meta". + return INVALID; + } + + /** + * Parses a file stream. + * + * The file type is checked through the "ftyp" box. + * + * @return bool True if the input stream is an AVIF bitstream or false. + */ + public function parse_ftyp() { + $box = new Box(); + $status = $box->parse( $this->handle, $this->num_parsed_boxes ); + if ( $status != FOUND ) { + return false; + } + + if ( $box->type != 'ftyp' ) { + return false; + } + // Iterate over brands. See ISO/IEC 14496-12:2012(E) 4.3.1 + if ( $box->content_size < 8 ) { + return false; + } + for ( $i = 0; $i + 4 <= $box->content_size; $i += 4 ) { + if ( !( $data = read( $this->handle, 4 ) ) ) { + return false; + } + if ( $i == 4 ) { + continue; // Skip minor_version. + } + if ( substr( $data, 0, 4 ) == 'avif' || substr( $data, 0, 4 ) == 'avis' ) { + return skip( $this->handle, $box->content_size - ( $i + 4 ) ); + } + if ( $i > 32 * 4 ) { + return false; // Be reasonable. + } + + } + return false; // No AVIF brand no good. + } + + /** + * Parses a file stream. + * + * Features are extracted from the "meta" box. + * + * @return bool True if the main features of the primary item were parsed or false. + */ + public function parse_file() { + $box = new Box(); + while ( $box->parse( $this->handle, $this->num_parsed_boxes ) == FOUND ) { + if ( $box->type === 'meta' ) { + if ( $this->parse_meta( $box->content_size ) != FOUND ) { + return false; + } + return true; + } + if ( !skip( $this->handle, $box->content_size ) ) { + return false; + } + } + return false; // No "meta" no good. + } +} |