155 lines
4.1 KiB
PHP
155 lines
4.1 KiB
PHP
<?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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/**
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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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}
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