hls-test/HLS/StreamReader.php

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2023-04-04 16:57:12 +00:00
<?php
/**
* Base class for streaming media segment readers
*
* @file
* @ingroup HLS
*/
namespace MediaWiki\TimedMediaHandler\HLS;
use Exception;
/**
* Base class for reading/writing a media file with wrappers
* for exception handling and possible multi usage.
*/
class StreamReader {
/**
* @var resource
*/
protected $file;
protected int $pos;
/**
* @param resource $file
*/
public function __construct( $file ) {
if ( get_resource_type( $file ) !== 'stream' ) {
throw new Exception( 'Invalid file stream' );
}
$this->file = $file;
$this->pos = $this->tell();
}
private function tell(): int {
return ftell( $this->file );
}
public function pos(): int {
return $this->pos;
}
/**
* Seek to given absolute file position.
* @throws Exception on error
*/
public function seek( int $pos ): void {
$this->pos = intval( $pos );
if ( $this->pos === $this->tell() ) {
return;
}
$retval = fseek( $this->file, $this->pos, SEEK_SET );
if ( $retval < 0 ) {
throw new Exception( "Failed to seek to $this->pos bytes" );
}
}
/**
* Read $len bytes or return null on EOF/short read.
* @throws Exception on error
*/
public function read( int $len ): ?string {
$this->seek( $this->pos );
$bytes = fread( $this->file, $len );
if ( $bytes === false ) {
throw new Exception( "Read error for $len bytes at $this->pos" );
}
if ( strlen( $bytes ) < $len ) {
return null;
}
$this->pos += strlen( $bytes );
return $bytes;
}
/**
* Read exactly $len bytes
* @throws Exception on error or short read
*/
public function readExactly( int $len ): string {
$bytes = $this->read( $len );
if ( $bytes === null ) {
throw new Exception( "Short read for $len bytes at $this->pos" );
}
return $bytes;
}
/**
* Write the given data and return number of bytes written.
* Short writes are possible on network connections, in theory.
* @throws Exception on error
*/
public function write( string $bytes ): int {
$this->seek( $this->pos );
$len = strlen( $bytes );
$nbytes = fwrite( $this->file, $bytes );
if ( $nbytes === false ) {
throw new Exception( "Write error for $len bytes at $this->pos" );
}
return $nbytes;
}
}