Req #63510 [Asn]: Integer overflow with chr
Edit report at https://bugs.php.net/bug.php?id=63510&edit=1
ID: 63510
Updated by: cmb@php.net
Reported by: idokan at gmail dot com
Summary: Integer overflow with chr
Status: Assigned
Type: Feature/Change Request
Package: Strings related
PHP Version: 5.4.8
Assigned To: yohgaki
Block user comment: N
Private report: N
New Comment:
It seems to be appropriate to point out why this ticket had been
changed to feature request. :)
> Not to $value & 255 it.
Actually, the integer is simply cast to char and used as the first
and only byte of the returned string[1].
Of course, this behavior is questionable, but changing it would
cause a BC break, so it can't be done in a minor version or even a
patch release without a very good reason. Simply stating "you must
report an error like XYZ" is not a very good reason, in my
opinion. I'd rather fix the docs and maybe change the behavior in
the next major version.
[1] <https://github.com/php/php-src/blob/php-7.0.8/ext/standard/string.c#L2793>
Previous Comments:
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[2012-11-14 15:36:32] idokan at gmail dot com
Huh ?!
ASCII is 0..127 chars, if they are out of range and also from extended ASCII (128..255), then you
must report an error like with normal implementation such as Ruby, Python, Pascal, Perl (with strict
bytes) etc...
Not to $value & 255 it.
------------------------------------------------------------------------
[2012-11-14 15:28:28] laruence@php.net
I think this check could be done in user script self.
the document said:
chr convert *ascii* code .. so...
------------------------------------------------------------------------
[2012-11-14 09:36:12] idokan at gmail dot com
Description:
------------
The chr function translate a single Byte length integer into it's ASCII value.
When providing a number bigger then 255, it returns the first byte instead of reporting an error
about being out of range.
Test script:
---------------
echo chr(1000) . ' ' . ord(chr(1000)) . "\n";
Expected result:
----------------
chr must check the numeric boundaries and report on on an error when they are out of the range.
Actual result:
--------------
returns the first byte out of the result, making it appear like an integer overflow that the carry
flag exception was captured.
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