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Request #70753 Default value of sem_get()'s parameter auto_release
Submitted: 2015-10-20 21:59 UTC Modified: 2020-11-16 16:51 UTC
From: kakkau at grr dot la Assigned:
Status: Suspended Package: Semaphore related
PHP Version: Irrelevant OS:
Private report: No CVE-ID: None
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 [2015-10-20 21:59 UTC] kakkau at grr dot la
Set the default value for sem_get()'s parameter auto_release to 0 as 1 allows additional acquisition of semaphores when reassigning semaphore resource identifiers although the semaphore was not released yet.

Test script:

class Sem {
  private $key = null;
  private $res = null;
  public function __construct() {
    $this->key = ftok(".",".");
  public function set_res() {
    // 4th parameter auto_released is 1 by default
    $this->res = sem_get($this->key, 1, 0600, 1);
  public function acquire() {
    echo "acquired='".sem_acquire($this->res,true)."'\n";

$s = new Sem();
// NOTE: it allows additional acquisition for simple resource variables too


Expected result:

Actual result:


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 [2020-11-16 16:51 UTC]
-Status: Open +Status: Suspended
 [2020-11-16 16:51 UTC]
Changing a default value of a function can cause a serious BC
break.  As such this request needs to be discussed on the
internals mailing list.  Please forward your request.  For the
time being, I'm suspending this ticket.
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