ReadLimitEntityBody.php

<?php

namespace Guzzle\Http;


/**
 * EntityBody decorator used to return only a subset of an entity body
 */
class ReadLimitEntityBody extends AbstractEntityBodyDecorator {

  /**
   * @var int Limit the number of bytes that can be read
   */
  protected $limit;

  /**
   * @var int Offset to start reading from
   */
  protected $offset;

  /**
   * @param EntityBodyInterface $body   Body to wrap
   * @param int                 $limit  Total number of bytes to allow to be read from the stream
   * @param int                 $offset Position to seek to before reading (only works on seekable streams)
   */
  public function __construct(EntityBodyInterface $body, $limit, $offset = 0) {
    parent::__construct($body);
    $this
      ->setLimit($limit)
      ->setOffset($offset);
    $this->body
      ->seek($offset);
  }

  /**
   * Returns only a subset of the decorated entity body when cast as a string
   * {@inheritdoc}
   */
  public function __toString() {
    return substr((string) $this->body, $this->offset, $this->limit);
  }

  /**
   * {@inheritdoc}
   */
  public function isConsumed() {
    return $this->offset + $this->limit - $this->body
      ->ftell() <= 0;
  }

  /**
   * Returns the Content-Length of the limited subset of data
   * {@inheritdoc}
   */
  public function getContentLength() {
    $length = $this->body
      ->getContentLength();
    return $length === false ? $this->limit : min($this->limit, min($length, $this->offset + $this->limit) - $this->offset);
  }

  /**
   * Allow for a bounded seek on the read limited entity body
   * {@inheritdoc}
   */
  public function seek($offset, $whence = SEEK_SET) {
    return $whence === SEEK_SET ? $this->body
      ->seek(max($this->offset, min($this->offset + $this->limit, $offset))) : false;
  }

  /**
   * Set the offset to start limiting from
   *
   * @param int $offset Offset to seek to and begin byte limiting from
   *
   * @return self
   */
  public function setOffset($offset) {
    $this->body
      ->seek($offset);
    $this->offset = $offset;
    return $this;
  }

  /**
   * Set the limit of bytes that the decorator allows to be read from the stream
   *
   * @param int $limit Total number of bytes to allow to be read from the stream
   *
   * @return self
   */
  public function setLimit($limit) {
    $this->limit = $limit;
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function read($length) {

    // Check if the current position is less than the total allowed bytes + original offset
    $remaining = $this->offset + $this->limit - $this->body
      ->ftell();
    if ($remaining > 0) {

      // Only return the amount of requested data, ensuring that the byte limit is not exceeded
      return $this->body
        ->read(min($remaining, $length));
    }
    else {
      return false;
    }
  }

}