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Snippet Name: Download File To Client

Description: Here's a function for sending a file to the client - it may look more complicated than necessary, but has a number of advantages over simpler file sending functions:

- Works with large files, and uses only an 8KB buffer per transfer.

- Stops transferring if the client is disconnected (unlike many scripts, that continue to read and buffer the entire file, wasting valuable resources) but does not halt the script

- Returns TRUE if transfer was completed, or FALSE if the client was disconnected before completing the download - you'll often need this, so you can log downloads correctly.

- Sends a number of headers, including ones that ensure it's cached for a maximum of 2 hours on any browser/proxy, and "Content-Length" which most people seem to forget.

(tested on Linux (Apache) and Windows (IIS5/6) under PHP4.3.x)

Note that the folder from which protected files will be pulled, is set as a constant in this function (/protected) ... Now here's the function:

Comment: (none)

Language: PHP
Highlight Mode: PHP
Last Modified: March 16th, 2009

<?PHP
 
FUNCTION send_file($name) {
  OB_END_CLEAN();
  $path = "protected/".$name;
  IF (!IS_FILE($path) or CONNECTION_STATUS()!=0) RETURN(FALSE);
  HEADER("Cache-Control: no-store, no-cache, must-revalidate");
  HEADER("Cache-Control: post-check=0, pre-check=0", FALSE);
  HEADER("Pragma: no-cache");
  HEADER("Expires: ".GMDATE("D, d M Y H:i:s", MKTIME(DATE("H")+2, DATE("i"), DATE("s"), DATE("m"), DATE("d"), DATE("Y")))." GMT");
  HEADER("Last-Modified: ".GMDATE("D, d M Y H:i:s")." GMT");
  HEADER("Content-Type: application/octet-stream");
  HEADER("Content-Length: ".(string)(FILESIZE($path)));
  HEADER("Content-Disposition: inline; filename=$name");
  HEADER("Content-Transfer-Encoding: binary\n");
  IF ($file = FOPEN($path, 'rb')) {
   WHILE(!FEOF($file) and (CONNECTION_STATUS()==0)) {
     PRINT(FREAD($file, 1024*8));
     FLUSH();
   }
   FCLOSE($file);
  }
  RETURN((CONNECTION_STATUS()==0) and !CONNECTION_ABORTED());
}
 
?>
 
 
And here's an example of using the function:
 
<?PHP
 
IF (!send_file("platinumdemo.zip")) {
DIE ("file transfer failed");
 
// either the file transfer was incomplete
// or the file was not found
 
} ELSE {
 
// the download was a success
// log, or do whatever else
}
 
?> 


 
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