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Bug #35470 Assigning global using variable name from array doesn't function
Submitted: 2005-11-29 11:32 UTC Modified: 2005-11-30 12:46 UTC
From: prgallier at yahoo dot com Assigned: dmitry
Status: Closed Package: Scripting Engine problem
PHP Version: 5CVS-2005-11-29 (cvs) OS: *
Private report: No CVE-ID:
 [2005-11-29 11:32 UTC] prgallier at yahoo dot com
Description:
------------
The below code does not store the value "55" in the variable "test" as it should, and did in PHP 5.0.5.  Leaving out the global declaration allows the output to display properly.  I have also had segmentation faults caused by similar routines, but have been unable to reproduce this outside of the full program.

Reproduce code:
---------------
$x = array("test", "55");
global ${$x[0]};
${$x[0]} = $x[1];
echo "Test: $test<br>\n";;


Expected result:
----------------
Displays:
Test: 

Actual result:
--------------
Should display:
Test: 55


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 [2005-11-29 11:33 UTC] prgallier at yahoo dot com
Oops...the expected and actual result fields are switched.
 [2005-11-29 13:09 UTC] sniper@php.net
Dmitry, can you check this out please.
 [2005-11-29 19:58 UTC] prgallier at yahoo dot com
The following generates a segfault on my system:

function dotest()
{
  $link = mysql_connect("localhost","test","test");
  mysql_select_db("test");
  mysql_query("CREATE TABLE config (num smallint(5) unsigned NOT NULL auto_increment, conf varchar(20) NOT NULL default '')");
  mysql_query("INSERT INTO config (conf,type) VALUES('Test1','33')");
  $result = mysql_query("SELECT conf,value FROM config");
  while ($row = mysql_fetch_row($result))
  {
    global ${$row[0]};
    ${$row[0]} = $row[1];
  }
  mysql_free_result($result);
}

dotest();
echo "Test: $test<br>\n";
 [2005-11-29 20:11 UTC] tony2001@php.net
<?php
function dotest()
{
    $array = array(array("test", "blah"),array("test", "blah"));
    $i = 0;
      while ($row = $array[$i++])
      {
          global ${$row[0]};
          ${$row[0]} = $row[1];
      }
}

dotest();
?>

Valgrind shows several errors:
==3742== Invalid read of size 4
==3742==    at 0x823AAEA: zend_fetch_dimension_address (zend_execute.c:1092)
==3742==    by 0x826DEE0: ZEND_FETCH_DIM_R_SPEC_CV_CONST_HANDLER (zend_vm_execute.h:20390)
==3742==    by 0x823B348: execute (zend_vm_execute.h:88)
==3742==    by 0x823B7A9: zend_do_fcall_common_helper_SPEC (zend_vm_execute.h:222)
==3742==    by 0x823E294: ZEND_DO_FCALL_SPEC_CONST_HANDLER (zend_vm_execute.h:1578)
==3742==    by 0x823B348: execute (zend_vm_execute.h:88)
==3742==    by 0x8214E75: zend_execute_scripts (zend.c:1090)
==3742==    by 0x81D43AD: php_execute_script (main.c:1704)
==3742==    by 0x828025D: main (php_cli.c:1039)

etc.
 [2005-11-30 11:10 UTC] dmitry@php.net
Fixed in CVS HEAD and PHP_5_1.
 [2005-11-30 12:46 UTC] prgallier at yahoo dot com
Tested and working great here.  Kudos to Dmitry!
 
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