LimitStream.php in Lockr 7.3

Namespace

GuzzleHttp\Psr7

File

vendor/guzzlehttp/psr7/src/LimitStream.php

<?php

namespace GuzzleHttp\Psr7;

use Psr\Http\Message\StreamInterface;

/**
 * Decorator used to return only a subset of a stream
 */
class LimitStream implements StreamInterface {
  use StreamDecoratorTrait;

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

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

  /**
   * @param StreamInterface $stream Stream to wrap
   * @param int             $limit  Total number of bytes to allow to be read
   *                                from the stream. Pass -1 for no limit.
   * @param int             $offset Position to seek to before reading (only
   *                                works on seekable streams).
   */
  public function __construct(StreamInterface $stream, $limit = -1, $offset = 0) {
    $this->stream = $stream;
    $this
      ->setLimit($limit);
    $this
      ->setOffset($offset);
  }
  public function eof() {

    // Always return true if the underlying stream is EOF
    if ($this->stream
      ->eof()) {
      return true;
    }

    // No limit and the underlying stream is not at EOF
    if ($this->limit == -1) {
      return false;
    }
    return $this->stream
      ->tell() >= $this->offset + $this->limit;
  }

  /**
   * Returns the size of the limited subset of data
   * {@inheritdoc}
   */
  public function getSize() {
    if (null === ($length = $this->stream
      ->getSize())) {
      return null;
    }
    elseif ($this->limit == -1) {
      return $length - $this->offset;
    }
    else {
      return min($this->limit, $length - $this->offset);
    }
  }

  /**
   * Allow for a bounded seek on the read limited stream
   * {@inheritdoc}
   */
  public function seek($offset, $whence = SEEK_SET) {
    if ($whence !== SEEK_SET || $offset < 0) {
      throw new \RuntimeException(sprintf('Cannot seek to offset % with whence %s', $offset, $whence));
    }
    $offset += $this->offset;
    if ($this->limit !== -1) {
      if ($offset > $this->offset + $this->limit) {
        $offset = $this->offset + $this->limit;
      }
    }
    $this->stream
      ->seek($offset);
  }

  /**
   * Give a relative tell()
   * {@inheritdoc}
   */
  public function tell() {
    return $this->stream
      ->tell() - $this->offset;
  }

  /**
   * Set the offset to start limiting from
   *
   * @param int $offset Offset to seek to and begin byte limiting from
   *
   * @throws \RuntimeException if the stream cannot be seeked.
   */
  public function setOffset($offset) {
    $current = $this->stream
      ->tell();
    if ($current !== $offset) {

      // If the stream cannot seek to the offset position, then read to it
      if ($this->stream
        ->isSeekable()) {
        $this->stream
          ->seek($offset);
      }
      elseif ($current > $offset) {
        throw new \RuntimeException("Could not seek to stream offset {$offset}");
      }
      else {
        $this->stream
          ->read($offset - $current);
      }
    }
    $this->offset = $offset;
  }

  /**
   * Set the limit of bytes that the decorator allows to be read from the
   * stream.
   *
   * @param int $limit Number of bytes to allow to be read from the stream.
   *                   Use -1 for no limit.
   */
  public function setLimit($limit) {
    $this->limit = $limit;
  }
  public function read($length) {
    if ($this->limit == -1) {
      return $this->stream
        ->read($length);
    }

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

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

}

Classes

Name	Description
LimitStream	Decorator used to return only a subset of a stream