Trying to access array offset on value of type bool after switching to PHP 8.0

Question

Getting the above warning for the following line of code:

switch ( $imagetype[2] ) {

The rest of the code for this below:

function nzshpcrt_display_preview_image() {
global $wpdb;
if ( (isset( $_GET['wpsc_request_image'] ) && ($_GET['wpsc_request_image'] == 'true'))
        || (isset( $_GET['productid'] ) && is_numeric( $_GET['productid'] ))
        || (isset( $_GET['image_id'] ) && is_numeric( $_GET['image_id'] ))
        || (isset( $_GET['image_name'] ))
) {

    if ( function_exists( "getimagesize" ) ) {

        $imagepath   = '';
        $category_id = 0;

        if(isset($_GET['image_name'] )) {
            $image = basename( $_GET['image_name'] );
            $imagepath = WPSC_USER_UPLOADS_DIR . $image;
        } else if ( isset($_GET['category_id'] )) {
            $category_id = absint( $_GET['category_id'] );
            $image = $wpdb->get_var( $wpdb->prepare( "SELECT `image` FROM `" . WPSC_TABLE_PRODUCT_CATEGORIES . "` WHERE `id` = %d LIMIT 1", $category_id ) );
            if ( $image != '' ) {
                $imagepath = WPSC_CATEGORY_DIR . $image;
            }
        }

        if ( ! is_file( $imagepath ) ) {
            $imagepath = WPSC_FILE_PATH . "/images/no-image-uploaded.gif";
        }

        $image_size = @getimagesize( $imagepath );
        if ( is_numeric( $_GET['height'] ) && is_numeric( $_GET['width'] ) ) {
            $height = (int)$_GET['height'];
            $width = (int)$_GET['width'];
        } else {
            $width = $image_size[0];
            $height = $image_size[1];
        }
        if ( !(($height > 0) && ($height <= 1024) && ($width > 0) && ($width <= 1024)) ) {
            $width = $image_size[0];
            $height = $image_size[1];
        }

        $product_id = (int) $_GET ??'' ['productid'];
        $image_id   = (int) $_GET ??'' ['image_id'];

        if ( $product_id > 0 ) {
            $cache_filename = basename( "product_{$product_id}_{$height}x{$width}" );
        } else if ( $category_id > 0 ) {
            $cache_filename = basename( "category_{$category_id}_{$height}x{$width}" );
        } else {
            $cache_filename = basename( "product_img_{$image_id}_{$height}x{$width}" );
        }

        $imagetype = @getimagesize( $imagepath );
        $use_cache = false;
        switch ( $imagetype[2]?? '') {
            case IMAGETYPE_GIF:
                $extension = ".gif";
                break;

            case IMAGETYPE_PNG:
                $extension = ".png";
                break;

            case IMAGETYPE_JPEG:
            default:
                $extension = ".jpg";
                break;

        }
        if ( file_exists( WPSC_CACHE_DIR . $cache_filename . $extension ) ) {
            $original_modification_time = filemtime( $imagepath );
            $cache_modification_time = filemtime( WPSC_CACHE_DIR . $cache_filename . $extension );
            if ( $original_modification_time < $cache_modification_time ) {
                $use_cache = true;
            }
        }

        if ( $use_cache === true ) {
            $cache_url = set_url_scheme( WPSC_CACHE_URL );
            header( "Location: " . $cache_url . $cache_filename . $extension );
            exit( '' );
        } else {
            switch ( $imagetype[2] ) {
                case IMAGETYPE_JPEG:
                    $src_img = imagecreatefromjpeg( $imagepath );
                    $pass_imgtype = true;
                    break;

                case IMAGETYPE_GIF:
                    $src_img = imagecreatefromgif( $imagepath );
                    $pass_imgtype = true;
                    break;

                case IMAGETYPE_PNG:
                    $src_img = imagecreatefrompng( $imagepath );
                    $pass_imgtype = true;
                    break;

                default:
                    $src_img      = false;
                    $pass_imgtype = false;
                    break;
            }

            if ( $pass_imgtype === true && $src_img ) {
                $source_w = imagesx( $src_img );
                $source_h = imagesy( $src_img );

                //Temp dimensions to crop image properly
                $temp_w = $width;
                $temp_h = $height;

                // select our scaling method
                $scaling_method = apply_filters( 'wpsc_preview_image_cropping_method', 'cropping' );

                // set both offsets to zero
                $offset_x = $offset_y = 0;

                // Here are the scaling methods, non-cropping causes black lines in tall images, but doesnt crop images.
                switch ( $scaling_method ) {
                    case 'cropping':
                        // if the image is wider than it is high and at least as wide as the target width.
                        if ( ($source_h <= $source_w ) ) {
                            if ( $height < $width ) {
                                $temp_h = ($width / $source_w) * $source_h;
                            } else {
                                $temp_w = ($height / $source_h) * $source_w;
                            }
                        } else {
                            $temp_h = ($width / $source_w) * $source_h;
                        }
                        break;

                    case 'non-cropping':
                    default:
                        if ( $height < $width ) {
                            $temp_h = ($width / $source_w) * $source_h;
                        } else {
                            $temp_w = ($height / $source_h) * $source_w;
                        }
                        break;
                }

                // Create temp resized image
                $bgcolor_default = apply_filters( 'wpsc_preview_image_bgcolor', array( 255, 255, 255 ) );
                $temp_img = ImageCreateTrueColor( $temp_w, $temp_h );
                $bgcolor = ImageColorAllocate( $temp_img, $bgcolor_default[0], $bgcolor_default[1], $bgcolor_default[2] );
                ImageFilledRectangle( $temp_img, 0, 0, $temp_w, $temp_h, $bgcolor );
                ImageAlphaBlending( $temp_img, true );
                ImageCopyResampled( $temp_img, $src_img, 0, 0, 0, 0, $temp_w, $temp_h, $source_w, $source_h );

                $dst_img = ImageCreateTrueColor( $width, $height );
                $bgcolor = ImageColorAllocate( $dst_img, $bgcolor_default[0], $bgcolor_default[1], $bgcolor_default[2] );
                ImageFilledRectangle( $dst_img, 0, 0, $width, $height, $bgcolor );
                ImageAlphaBlending( $dst_img, true );

                // X & Y Offset to crop image properly
                if ( $temp_w < $width ) {
                    $w1 = ($width / 2) - ($temp_w / 2);
                } else if ( $temp_w == $width ) {
                    $w1 = 0;
                } else {
                    $w1 = ($width / 2) - ($temp_w / 2);
                }

                if ( $temp_h < $height ) {
                    $h1 = ($height / 2) - ($temp_h / 2);
                } else if ( $temp_h == $height ) {
                    $h1 = 0;
                } else {
                    $h1 = ($height / 2) - ($temp_h / 2);
                }

                switch ( $scaling_method ) {
                    case 'cropping':
                        ImageCopy( $dst_img, $temp_img, $w1, $h1, 0, 0, $temp_w, $temp_h );
                        break;

                    case 'non-cropping':
                    default:
                        ImageCopy( $dst_img, $temp_img, 0, 0, 0, 0, $temp_w, $temp_h );
                        break;
                }

                $image_quality = wpsc_image_quality();

                ImageAlphaBlending( $dst_img, false );
                switch ( $imagetype[2] ) {
                    case IMAGETYPE_JPEG:
                        header( "Content-type: image/jpeg" );
                        imagejpeg( $dst_img );
                        imagejpeg( $dst_img, WPSC_CACHE_DIR . $cache_filename . '.jpg', $image_quality );
                        @ chmod( WPSC_CACHE_DIR . $cache_filename . ".jpg", 0775 );
                        break;

                    case IMAGETYPE_GIF:
                        header( "Content-type: image/gif" );
                        ImagePNG( $dst_img );
                        ImagePNG( $dst_img, WPSC_CACHE_DIR . $cache_filename . ".gif" );
                        @ chmod( WPSC_CACHE_DIR . $cache_filename . ".gif", 0775 );
                        break;

                    case IMAGETYPE_PNG:
                        header( "Content-type: image/png" );
                        ImagePNG( $dst_img );
                        ImagePNG( $dst_img, WPSC_CACHE_DIR . $cache_filename . ".png" );
                        @ chmod( WPSC_CACHE_DIR . $cache_filename . ".png", 0775 );
                        break;

                    default:
                        $pass_imgtype = false;
                        break;
                }
                exit();
            }
        }
    }
}

}

Any suggestions or help on how to resolve this would be greatly appreciated!

Answer 1

You errors come from getimagesize() here you can find the doc, it can return "false" witch is you case here, cause your image file is impossible to access, I suppose. https://www.php.net/manual/en/function.getimagesize.php

You should add verification on return value getimagesize. Or use try/catch