Edit report at https://bugs.php.net/bug.php?id=61998&edit=1
ID: 61998
Comment by: dmitry at zend dot com
Reported by: rbarbosa at revelex dot com
Summary: Using traits with method aliases appears to result
in crash during execution.
Status: Feedback
Type: Bug
Package: Reproducible crash
Operating System: Redhat Linux - Kernel 2.6.18
PHP Version: 5.4.3
Assigned To: dmitry
Block user comment: N
Private report: N
New Comment:
I think my patch is more clear. Please take a look if you see any problems with
it.
The malloc -> emalloc part of your patch, that is not directly related to this
bug, makes full sense. I think you can commit it.
Previous Comments:
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[2012-05-19 06:17:48] [email protected]
Dmitry, could you please look at the patch(attached) for this? thanks
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[2012-05-19 06:17:00] [email protected]
The following patch has been added/updated:
Patch Name: bug61998.phpt
Revision: 1337408220
URL:
https://bugs.php.net/patch-display.php?bug=61998&patch=bug61998.phpt&revision=1337408220
------------------------------------------------------------------------
[2012-05-19 06:16:38] [email protected]
The following patch has been added/updated:
Patch Name: bug61998.patch
Revision: 1337408198
URL:
https://bugs.php.net/patch-display.php?bug=61998&patch=bug61998.patch&revision=1337408198
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[2012-05-15 04:32:31] reeze dot xia at gmail dot com
Thanks ron for your test script. I've make a minimal reproducible one below:
In Class1:
newFunc was referred to T::func
func was itself (by overriding);
In T
func was referred by T and itself;
--- since class was destroyed by reverse order --
1. Destroy Tï¼ will not release the function name defined in trait. since
the Class1 referred to this function.
2. Destroy Class1ï¼it will destroy the alias name since the aliased
function name was referred to it.(this leave the original function name
in trait unreleased). after destroy function table it will destroy
alias info. but alias was already destroyed in function table releasing
phrase.
This cause double free(crash).
Solutions:
1. Copy the whole function will solve the problem. but it was too heavy.
2. Don't change the aliases function's name, since function call are always
lookup by hash key name.
but it will make reflection unhappy and can't throw right error message for
function.
3. Make a reference in function table if trait function was overrided to avoid
releasing problem.
This need to change reflection ignore it.get_defined_functions() &
get_delcared_clesses()
use this trick to filter special entry. so we need to change
ReflectionClass::getMethods().
In summary I prefer option 3. What do you think?
and I made PR: https://github.com/php/php-src/pull/83
------ Test script ---------------
<?php
class Class1 {
use T {
func as newFunc;
}
public function func() { // <------------ if this override trait method and
the method get aliased will lead crash
echo "From Class1::func\n";
}
}
class Class2 {
use T;
}
trait T { // <------------------------------ declare after the Class1 and it
will be destroy before Class1
public function func() {
echo "From trait T\n";
}
}
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[2012-05-11 01:04:06] [email protected]
Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves.
A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external
resources such as databases, etc. If the script requires a
database to demonstrate the issue, please make sure it creates
all necessary tables, stored procedures etc.
Please avoid embedding huge scripts into the report.
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the rest of the comments, please view the bug report online at
https://bugs.php.net/bug.php?id=61998
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