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Bug #25662 Bug in zend_fetch_constant_handler
Submitted: 2003-09-25 15:54 UTC Modified: 2003-09-26 05:38 UTC
From: cliff at may dot be Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 5CVS-2003-09-25 (dev) OS: Linux
Private report: No CVE-ID: None
View Developer Edit
 [2003-09-25 15:54 UTC] cliff at may dot be 
Description:
------------
When the wrong value is used for a constant, the error message repeats the erroneous constant in the warning.  I don't totally understand the code but it appears to be trying to use the erroneous value too.  So either just the second 
  EX(opline)->op2.u.constant.value.str.val
needs to be changed or the code needs fixing too.

Reproduce code:
---------------
if (!zend_get_constant(EX(opline)->op2.u.constant.value.str.val,
 EX(opline)->op2.u.constant.value.str.len, &EX_T(EX(opline)->result.u.var).tmp_v
ar TSRMLS_CC)) {
    zend_error(E_NOTICE, "Use of undefined constant %s - assumed '%s'", EX(opline)->op2.u.constant.value.str.val,     EX(opline)->op2.u.constant.value.str.val);
    EX_T(EX(opline)->result.u.var).tmp_var = EX(opline)->op2.u.constant;
zval_copy_ctor(&EX_T(EX(opline)->result.u.var).tmp_var);
}


Expected result:
----------------
Notice: Use of undefined constant EXTRACT_OVERWRITE - assumed 'EXTR_OVERWRITE' in ...

Actual result:
--------------
Notice: Use of undefined constant EXTRACT_OVERWRITE - assumed 'EXTRACT_OVERWRITE' in ...

Patches

Pull Requests

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AllCommentsChangesGit/SVN commitsRelated reports
 [2003-09-25 16:45 UTC] abies@php.net 
It assumes you meant (string)'EXTRACT_OVERWRITE' and uses that instead of the constant's value.
 [2003-09-25 18:10 UTC] cliff at may dot be 
To what effect?  A string is not a legal value there.  IMHO, it should either use the default value or generate a fatal error.

Or am I missing something obvious?
 [2003-09-26 01:24 UTC] pollita@php.net 
It's a tradeoff, treating non-existant constants like strings allows for syntax like:

echo $myarray[fooindex]

to work.  It also allows what is a technicly legal parse:

echo "The output says: " . FOO;

to use FOO as a constant (if it's defined) or fallback on string behavior if it's not.

As to functions which expect a certain range of constants, how is PHP to know what the correct constant is?  To a human a typo of EXTR / EXTRACT seems obvious, to a machine it's less clear.  

By treating the non-constant as a string, we ensure that it will convert to an integer value of zero in the evaluating function and raise a proper error which, in conjunction with the undefined constant notice, should be enough to prompt the scripter to fix their code.

Conversely, if we were to treat a non-constant as a complete lack of a value (allowing the function to perform its default behavior) the typo would be masked sending the scripter off on a wild goose chance hunting the "bug" down.
 [2003-09-26 05:38 UTC] cliff at may dot be 
OK.  Point taken.  In that case I would simply suggest the message be made clearer, on the lines of:

"Use of undefined constant %s - using string '%s'"

Thanks for your explanation, by the way.
 
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