elkarte / Elkarte

sources/ElkArte/Graphics/Image.php

<?php

/**
 * This file deals with low-level graphics operations performed on images,
 * specifically as needed for avatars (uploaded avatars), attachments, or
 * visual verification images.
 *
 * TrueType fonts supplied by www.LarabieFonts.com
 *
 * @package   ElkArte Forum
 * @copyright ElkArte Forum contributors
 * @license   BSD http://opensource.org/licenses/BSD-3-Clause (see accompanying LICENSE.txt file)
 *
 * @version 2.0 Beta 1
 *
 */

namespace ElkArte\Graphics;

use ElkArte\Exceptions\Exception;
use ElkArte\Graphics\Manipulators\Gd2;
use ElkArte\Graphics\Manipulators\ImageMagick;
use ElkArte\Helper\FileFunctions;

/**
 * Class Image
 *
 * Base class for image function and interaction with the various graphic engines (GD/IMagick)
 *
 * @package ElkArte\Graphics
 */
class Image
{
	/** @var array The image formats we will work with */
	public const DEFAULT_FORMATS = [
		IMAGETYPE_GIF => 'gif',
		IMAGETYPE_JPEG => 'jpeg',
		IMAGETYPE_PNG => 'png',
		IMAGETYPE_BMP => 'bmp',
		IMAGETYPE_WBMP => 'wbmp',
		IMAGETYPE_WEBP => 'webp'
	];

	/** @var ImageMagick|Gd2 */
	protected $_manipulator;

	/** @var string filename we are working with */
	protected $_fileName = '';

	/** @var bool if the image has been loaded into the manipulator */
	protected $_image_loaded = false;

	/** @var string what manipulator (GD, ImageMagick, etc.) is in use */
	protected $_current_manipulator = '';

	/**
	 * Image constructor.
	 *
	 * @param string $fileName
	 * @param bool $_force_gd
	 */
	public function __construct($fileName, protected $_force_gd = false)
	{
		$this->setFileName($fileName);

		$this->loadImage();
	}

	/**
	 * Sets the filename / path in use
	 */
	public function setFileName($fileName): void
	{
		$this->_fileName = $fileName;
	}

	/**
	 * Check if the current manipulator supports webP
	 *
	 * @return bool
	 */
	public function hasWebpSupport(): bool
	{
		if (!$this->_force_gd && ImageMagick::canUse())
		{
			$check = \Imagick::queryformats();
			if (!in_array('WEBP', $check, true))
			{
				return false;
			}
		}

		if (Gd2::canUse())
		{
			$check = gd_info();
			if (empty($check['WebP Support']))
			{
				return false;
			}
		}

		return true;
	}

	/**
	 * Returns if the acp allows saving webP images
	 *
	 * @return bool
	 */
	public function canUseWebp(): bool
	{
		global $modSettings;

		// Enabled?
		if (empty($modSettings['attachment_webp_enable']))
		{
			return false;
		}

		return !(!empty($modSettings['attachmentCheckExtensions']) && stripos($modSettings['attachmentExtensions'], ',webp') === false);
	}

	/**
	 * Load an image from a file or web address into the active graphics library
	 */
	protected function loadImage()
	{
		// Determine and set what image library we will use
		try
		{
			$this->setManipulator();
		}
		catch (\Exception)
		{
			// Nothing to do
		}

		if ($this->isWebAddress())
		{
			$success = $this->_manipulator->createImageFromWeb();
		}
		else
		{
			$success = $this->_manipulator->createImageFromFile();
		}

		if ($success === true)
		{
			$this->_image_loaded = true;
		}
	}

	/**
	 * Returns if the loading of the image was successful
	 *
	 * @return bool
	 */
	public function isImageLoaded(): bool
	{
		return $this->_image_loaded && $this->isImage();
	}

	/**
	 * Determine and set what image library we will use
	 *
	 * @throws \Exception
	 */
	protected function setManipulator(): void
	{
		// Later this could become an array of "manipulators" (or not) and remove the hard-coded IM/GD requirements
		if (!$this->_force_gd && ImageMagick::canUse())
		{
			$this->_manipulator = new ImageMagick($this->_fileName);
			$this->_current_manipulator = 'ImageMagick';
		}
		elseif (Gd2::canUse())
		{
			$this->_manipulator = new Gd2($this->_fileName);
			$this->_current_manipulator = 'GD';
		}
		else
		{
			throw new \Exception('No image manipulators available');
		}
	}

	/**
	 * Returns the current image library in use.
	 *
	 * @return string
	 */
	public function getManipulator(): string
	{
		return $this->_current_manipulator ?? '';
	}

	/**
	 * Return if the source is actually a web address vs. local file
	 *
	 * @return bool
	 */
	protected function isWebAddress()
	{
		return str_starts_with($this->_fileName, 'http://') || str_starts_with($this->_fileName, 'https://');
	}

	/**
	 * It's how big?
	 *
	 * @return int
	 */
	public function getFilesize()
	{
		clearstatcache(false, $this->_fileName);

		$size = FileFunctions::instance()->fileSize($this->_fileName);

		return $size === false ? 0 : $size;
	}

	/**
	 * Best determination of the mime type.
	 *
	 * @return string
	 */
	public function getMimeType(): string
	{
		// Try Exif, which reads the file headers, most accurate for images
		if (function_exists('exif_imagetype'))
		{
			return image_type_to_mime_type(exif_imagetype($this->_fileName));
		}

		return getMimeType($this->_fileName);
	}

	/**
	 * If the file is an image or not
	 *
	 * @return bool
	 */
	public function isImage()
	{
		return str_starts_with($this->getMimeType(), 'image');
	}

	/**
	 * Creates a thumbnail from an image.
	 *
	 * - "Recipe" function to create, rotate, and save a thumbnail of a given image
	 * - Thumbnail will be proportional to the original image
	 * - Saves the thumbnail file
	 *
	 * @param int $max_width allowed width
	 * @param int $max_height allowed height
	 * @param string $dstName name to save
	 * @param null|int $format image format image constant value to save the thumbnail
	 * @param null|bool $force if forcing the image resize to scale up, the default action
	 * @return bool|Image On success returns an image class loaded with new image
	 */
	public function createThumbnail($max_width, $max_height, $dstName = '', $format = null, $force = null)
	{
		// The particulars
		$dstName = $dstName === '' ? $this->_fileName . '_thumb' : $dstName;
		$default_format = $this->getDefaultFormat();
		$format = empty($format) || !is_int($format) ? $default_format : $format;
		$max_width = max(16, $max_width);
		$max_height = max(16, $max_height);

		// Do the actual resize, thumbnails by default strip EXIF data to save space
		$success = $this->resizeImage($max_width, $max_height, true, $force ?? true, true);

		// Save our work
		if ($success)
		{
			$success = false;
			if ($this->saveImage($dstName, $format))
			{
				FileFunctions::instance()->chmod($dstName);
				$success = new Image($dstName);
			}
		}
		else
		{
			@touch($dstName);

It seems like you do not handle an error condition for touch(). This can introduce security issues, and is generally not recommended.

		}

		return $success;
	}

	/**
	 * Sets the best output format for a given image's thumbnail
	 *
	 * - If webP is available, use that as it gives the smallest size
	 * - No webP then, if the image has alpha, we preserve it
	 * - Finally good ol' jpeg
	 *
	 * @return int
	 */
	public function getDefaultFormat(): int
	{
		global $modSettings;

		// Webp is the best choice if server supports
		if (!empty($modSettings['attachment_webp_enable']) && $this->hasWebpSupport())
		{
			return IMAGETYPE_WEBP;
		}

		// They uploaded a webp image, but ACP does not allow saving webp images, then
		// if the server supports and its alpha save it as a png
		if ($this->getMimeType() === 'image/webp' && $this->hasWebpSupport() && $this->getTransparency(false))
		{
			return IMAGETYPE_PNG;
		}

		// If you have alpha channels, best keep them with PNG
		if ($this->getMimeType() !== 'image/png')
		{
			// The default, JPG
			return IMAGETYPE_JPEG;
		}

		if (!$this->getTransparency())
		{
			// The default, JPG
			return IMAGETYPE_JPEG;
		}

		return IMAGETYPE_PNG;
	}

	/**
	 * Calls functions to correct an images orientation based on the EXIF orientation flag
	 *
	 * @return bool
	 */
	public function autoRotate()
	{
		$this->getOrientation();

		// We only process jpeg images, so check that we have one
		if (!isset($this->_manipulator->imageDimensions[2]))
		{
			$this->_manipulator->getImageDimensions();
		}

		// Not a jpeg or not rotated, done!
		if ($this->_manipulator->imageDimensions[2] !== 2 || $this->_manipulator->orientation <= 1)
		{
			return false;
		}

		try
		{
			$this->_manipulator->autoRotate();
		}
		catch (\Exception)
		{
			return false;
		}

		return true;
	}

	/**
	 * Finds the orientation flag of the image as defined by its EXIF data
	 *
	 * @return int
	 */
	public function getOrientation(): int
	{
		return $this->_manipulator->getOrientation();
	}

	/**
	 * Resize an image from a remote location or a local file.
	 *
	 * What it does:
	 *
	 * - Resize an image, proportionally, to fit withing WxH limits
	 * - The file would have the format preferred_format if possible,
	 * otherwise the default format is jpeg.
	 * - Optionally removes exif header data to make a smaller image
	 *
	 * @param int $max_width The maximum allowed width
	 * @param int $max_height The maximum allowed height
	 * @param bool $strip Allow IM to remove exif data as GD always will
	 * @param bool $force_resize Always resize the image (force scale up)
	 * @param bool $thumbnail If the image is a small thumbnail version
	 *
	 * @return bool Whether the thumbnail creation was successful.
	 */
	public function resizeImage($max_width, $max_height, $strip = false, $force_resize = true, $thumbnail = false)
	{
		// Nothing to do without GD or IM or an Image
		if ($this->_manipulator === null)
		{
			return false;
		}

		try
		{
			return $this->_manipulator->resizeImage($max_width, $max_height, $strip, $force_resize, $thumbnail);
		}
		catch (\Exception)
		{
			return false;
		}
	}

	/**
	 * Save the image object to a file.
	 *
	 * @param string $file_name name to save the image to
	 * @param int $preferred_format what format to save the image
	 * @param int $quality some formats require we provide a compression quality
	 *
	 * @return bool
	 */
	public function saveImage($file_name = '', $preferred_format = IMAGETYPE_JPEG, $quality = 85)
	{
		return $this->_manipulator->output($file_name, $preferred_format, $quality);
	}

	/**
	 * Used to re-encode an image to a specified image format
	 *
	 * What it does:
	 *
	 * - Creates a copy of the file at the same location.
	 * - The file would have the format preferred_format if possible, otherwise the default format is jpeg.
	 * - Strips the exif data
	 * - The function makes sure that all non-essential image contents are disposed of.
	 *
	 * @return bool
	 */
	public function reEncodeImage()
	{
		// The image should already be loaded
		if (!$this->isImage())
		{
			return false;
		}

		// re-encode the image at the same size it is now, strip exif data.
		$sizes = $this->getImageDimensions();
		$success = $this->resizeImage($sizes[0], $sizes[1], true);

		// if all went well, and it's valid, save it back in place
		if ($success && !empty(self::DEFAULT_FORMATS[$sizes[2]]))
		{
			// Write over the original file
			$success = $this->saveImage($this->_fileName, $sizes[2]);
			$this->loadImage();
		}

		return $success;
	}

	/**
	 * Return or set (via getimagesize or getimagesizefromstring) some image details such
	 * as size and mime type
	 *
	 * @return array
	 */
	public function getImageDimensions(): array
	{
		return $this->_manipulator->imageDimensions;
	}

	/**
	 * Checks for transparency in a PNG image
	 *
	 *  - Checks file header for saved with Alpha space flag
	 *  - 8 Bit (256 color) PNGs are not handled.
	 *  - If png is false, will instead check webp headers for transparency flag
	 *  - If the alpha flag is set, will go pixel by pixel to validate true alpha pixels exist
	 *
	 * @param bool $png
	 *
	 * @return bool
	 */
	public function getTransparency($png = true): bool
	{
		// If it claims transparency, we do pixel inspection
		$header = file_get_contents($this->_fileName, false, null, 0, 26);

		// Does it even claim to have been saved with transparency?
		if ($png && ord($header[25]) & 4)
		{
			return $this->_manipulator->getTransparency();
		}

		// Webp has its own unique headers
		if (!$png)
		{
			if (($header[15] === 'L' && (ord($header[24]) & 16)) || ($header[15] === 'X' && (ord($header[20]) & 16)))
			{
				return $this->_manipulator->getTransparency();
			}
		}

		return false;
	}

	/**
	 * Searches through the file to see if there's potentially harmful content.
	 *
	 * What it does:
	 *
	 * - Basic search of an image file for potential web (php/script) infections
	 *
	 * @return bool
	 * @throws Exception
	 */
	public function checkImageContents()
	{
		$fp = fopen($this->_fileName, 'rb');

		// If we can't open it to scan, go no further
		if ($fp === false)
		{
			throw new Exception('Post.attach_timeout');
		}

		$prev_chunk = '';
		while (!feof($fp))
		{
			$cur_chunk = fread($fp, 256000);
			$test_chunk = $prev_chunk . $cur_chunk;

			// Though not exhaustive lists, better safe than sorry.
			if (preg_match('~<\\?php|<script\s+language\s*=\s*(?:php|"php"|\'php\')\s*>~i', $test_chunk) === 1)
			{
				fclose($fp);

				return false;
			}

			$prev_chunk = $cur_chunk;
		}

		fclose($fp);

		return true;
	}
}