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<?php
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declare(strict_types=1);
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namespace GuzzleHttp\Psr7;
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use Psr\Http\Message\StreamInterface;
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/**
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 * Decorator used to return only a subset of a stream.
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 */
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final class LimitStream implements StreamInterface
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{
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    use StreamDecoratorTrait;
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    /** @var int Offset to start reading from */
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    private $offset;
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    /** @var int Limit the number of bytes that can be read */
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    private $limit;
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    /** @var StreamInterface */
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    private $stream;
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    /**
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     * @param StreamInterface $stream Stream to wrap
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     * @param int             $limit  Total number of bytes to allow to be read
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     *                                from the stream. Pass -1 for no limit.
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     * @param int             $offset Position to seek to before reading (only
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     *                                works on seekable streams).
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     */
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    public function __construct(
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        StreamInterface $stream,
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        int $limit = -1,
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        int $offset = 0
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    ) {
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        $this->stream = $stream;
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        $this->setLimit($limit);
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        $this->setOffset($offset);
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    }
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    public function eof(): bool
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    {
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        // Always return true if the underlying stream is EOF
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        if ($this->stream->eof()) {
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            return true;
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        }
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        // No limit and the underlying stream is not at EOF
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        if ($this->limit === -1) {
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            return false;
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        }
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        return $this->stream->tell() >= $this->offset + $this->limit;
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    }
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    /**
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     * Returns the size of the limited subset of data
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     */
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    public function getSize(): ?int
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    {
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        if (null === ($length = $this->stream->getSize())) {
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            return null;
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        } elseif ($this->limit === -1) {
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            return $length - $this->offset;
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        } else {
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            return min($this->limit, $length - $this->offset);
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        }
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    }
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    /**
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     * Allow for a bounded seek on the read limited stream
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     */
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    public function seek($offset, $whence = SEEK_SET): void
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    {
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        if ($whence !== SEEK_SET || $offset < 0) {
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            throw new \RuntimeException(sprintf(
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                'Cannot seek to offset %s with whence %s',
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                $offset,
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                $whence
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            ));
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        }
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        $offset += $this->offset;
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        if ($this->limit !== -1) {
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            if ($offset > $this->offset + $this->limit) {
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                $offset = $this->offset + $this->limit;
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            }
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        }
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        $this->stream->seek($offset);
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    }
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    /**
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     * Give a relative tell()
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     */
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    public function tell(): int
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    {
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        return $this->stream->tell() - $this->offset;
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    }
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    /**
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     * Set the offset to start limiting from
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     *
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     * @param int $offset Offset to seek to and begin byte limiting from
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     *
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     * @throws \RuntimeException if the stream cannot be seeked.
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     */
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    public function setOffset(int $offset): void
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    {
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        $current = $this->stream->tell();
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        if ($current !== $offset) {
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            // If the stream cannot seek to the offset position, then read to it
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            if ($this->stream->isSeekable()) {
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                $this->stream->seek($offset);
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            } elseif ($current > $offset) {
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                throw new \RuntimeException("Could not seek to stream offset $offset");
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            } else {
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                $this->stream->read($offset - $current);
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            }
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        }
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        $this->offset = $offset;
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    }
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    /**
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     * Set the limit of bytes that the decorator allows to be read from the
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     * stream.
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     *
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     * @param int $limit Number of bytes to allow to be read from the stream.
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     *                   Use -1 for no limit.
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     */
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    public function setLimit(int $limit): void
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    {
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        $this->limit = $limit;
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    }
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    public function read($length): string
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    {
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        if ($this->limit === -1) {
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            return $this->stream->read($length);
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        }
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        // Check if the current position is less than the total allowed
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        // bytes + original offset
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        $remaining = ($this->offset + $this->limit) - $this->stream->tell();
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        if ($remaining > 0) {
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            // Only return the amount of requested data, ensuring that the byte
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            // limit is not exceeded
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            return $this->stream->read(min($remaining, $length));
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        }
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        return '';
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    }
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}