Bug #51344 [Asn->Wfx]: FILTER_NULL_ON_FAILURE flag automatically set in filter_input() functions.

Edit report at http://bugs.php.net/bug.php?id=51344&edit=1

 ID:               51344
 Updated by:       [email protected]
 Reported by:      pravila at alumni dot calpoly dot edu
 Summary:          FILTER_NULL_ON_FAILURE flag automatically set in
                   filter_input() functions.
-Status:           Assigned
+Status:           Wont fix
 Type:             Bug
 Package:          Filter related
 Operating System: Linux
 PHP Version:      5.2.13
 Assigned To:      aharvey

 New Comment:

This is going to sound insane when you've looked at the underlying
filter code, but this is actually correct according to the
documentation: the default behaviour of filter_input() is to return NULL
for non-existent inputs and false when validation fails, and
FILTER_NULL_ON_FAILURE simply flips that behaviour to false for
non-existent inputs and NULL on validation failure. (No, I don't have a
clue where that would be useful either, and the name of the flag is
unfortunate in the filter_input() context, since it implies that NULL
wouldn't normally be returned. It makes more sense when used with
filter_var(), which doesn't have the non-existent input case.)

A table showing the return value from filter_input() in the different
cases follows:

                       | "yes" | "no"  | "invalid" | non-existent |
No flags               | TRUE  | FALSE | FALSE     | NULL         |
FILTER_NULL_ON_FAILURE | TRUE  | FALSE | NULL      | FALSE        |

I'll pop a comment into the filter_input() and filter_input_array()
implementations to note that this is by design, even though the code
does kind of look wrong.

Closing Won't Fix.


Previous Comments:
------------------------------------------------------------------------
[2010-04-11 01:15:01] mats dot lindh at gmail dot com

Patch to solve issue has been added. Patch is against current trunk but
can probably be applied cleanly against 5.2 and 5.3 too. Issue stems
from a simple error where RETURN_NULL(); and RETURN_FALSE; statements
seems to have gotten mixed up.

Test is also attached in patch, based on the example in the bug report.

------------------------------------------------------------------------
[2010-03-21 18:02:46] pravila at alumni dot calpoly dot edu

Description:
------------
* This is different than bug http://bugs.php.net/bug.php?id=41305 *

The filter_var() vs. the filter_input() behave differently when using
the 
FILTER_VALIDATE_BOOLEAN filter when the variable/input doesn't exist.

More specifically, it seems as if the FILTER_NULL_ON_FAILURE flag is set

automatically in the filter_input() function.

(Note: same behavior for filter_var_array() vs. filter_input_array()).

From PHPINFO():
filter.default = unsafe_raw
filter.default_flags = no value
Revision: 1.52.2.39.2.16

Test script:
---------------
<?php
// example.com/script.php?arg1=yes&arg3=no

// filtering by variable
$var1 = filter_var($_GET["arg1"], FILTER_VALIDATE_BOOLEAN);
$var2 = filter_var($_GET["arg2"], FILTER_VALIDATE_BOOLEAN);
$var3 = filter_var($_GET["arg3"], FILTER_VALIDATE_BOOLEAN);

// filtering by input
$input1 = filter_input(INPUT_GET, "arg1", FILTER_VALIDATE_BOOLEAN);
$input2 = filter_input(INPUT_GET, "arg2", FILTER_VALIDATE_BOOLEAN);
$input3 = filter_input(INPUT_GET, "arg3", FILTER_VALIDATE_BOOLEAN);

// as expected...
var_dump($var1);      // bool(true)
var_dump($var2);      // bool(false)
var_dump($var3);      // bool(false)

// NULL is not an expected return unless the FILTER_NULL_ON_FAILURE flag
is set...
var_dump($input1);    // bool(true)
var_dump($input2);    // NULL
var_dump($input3);    // bool(false)
?>

Expected result:
----------------
As per the documentation, we expect the output of the code above to be:

bool(true)
bool(false)
bool(false)
bool(true)
bool(false)
bool(false)

Actual result:
--------------
Even though the FILTER_NULL_ON_FAILURE flag is NOT set, we DO get a NULL
value in 
the output:

bool(true)
bool(false)
bool(false)
bool(true)
NULL
bool(false)


------------------------------------------------------------------------



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Edit this bug report at http://bugs.php.net/bug.php?id=51344&edit=1