Let PHP support breakpoint continuation of the source code

For example, the first request for a file from 0 to 999 bytes, the second request 1000 to 1999 bytes, and so on, each request 1000 bytes of content, and then the program through the fseek function to obtain the corresponding file location, and then output.

$fname = './05e58c19552bb26b158f6621a6650899'; 
$fp = fopen($fname,'rb'); 
$fsize = filesize($fname); 
if (isset($_SERVER['HTTP_RANGE']) && ($_SERVER['HTTP_RANGE'] != "") && preg_match("/^bytes=([0-9]+)-$/i", $_SERVER['HTTP_RANGE'], $match) && ($match[1] < $fsize)) { 
$start = $match[1]; 
} else { 
$start = 0; 
} 
@header("Cache-control: public"); 
@header("Pragma: public"); 
if ($start > 0) { 
fseek($fp, $start); 
Header("HTTP/1.1 206 Partial Content"); 
Header("Content-Length: " . ($fsize - $start)); 
Header("Content-Ranges: bytes" . $start . "-" . ($fsize - 1) . "/" . $fsize); 
} else { 
header("Content-Length: $fsize"); 
Header("Accept-Ranges: bytes"); 
} 
@header("Content-Type: application/octet-stream"); 
@header("Content-Disposition: attachment;filename=1.rm"); 
fpassthru($fp); 

You can also check out Discuz! How does the attachment. PHP file of the forum software realize the continuation of breakpoint. See the code:

Is also through $_SERVER['HTTP_RANGE'] to get the user request file range, you can see the specific source code analysis. I'm going to throw out a brick here.

 
$range = 0; 
if($readmod == 4) { 
dheader('Accept-Ranges: bytes'); 
if(!emptyempty($_SERVER['HTTP_RANGE'])) { 
list($range) = explode('-',(str_replace('bytes=', '', $_SERVER['HTTP_RANGE']))); 
$rangesize = ($filesize - $range) > 0 ? ($filesize - $range) : 0; 
dheader('Content-Length: '.$rangesize); 
dheader('HTTP/1.1 206 Partial Content'); 
dheader('Content-Range: bytes='.$range.'-'.($filesize-1).'/'.($filesize)); 
} 
}