Edit report at https://bugs.php.net/bug.php?id=61660&edit=1
ID: 61660
Comment by: theanomaly dot is at gmail dot com
Reported by: krtek4+php at gmail dot com
Summary: bin2hex(hex2bin($data)) != $data
Status: Closed
Type: Bug
Package: *General Issues
Operating System: Debian Linux
PHP Version: 5.4.1RC1
Assigned To: nikic
Block user comment: N
Private report: N
New Comment:
The patch currently in master still leaves a remanent problem. First,
var_dump(hex2bin('')) still returns string(0) "". Whether or not this is
acceptable is arguable. Since 0x00 is null, but an empty string isn't really
null.
For example:
var_dump(unpack('H*',hex2bin(''))); // will give me string(0) ""
Whereas:
var_dump(unpack('H*',hex2bin('00'))); // will give me string(2) ""
and:
var_dump(hex2bin('00')); // will give me string(1) "" # which is what I expect
So the warning needs to be amended for an empty string as well as odd-sized hex.
Additionally, the function now returns a bool(false), breaking BC.
I suggest a second optional argument to return partial binary (potentially
broken binary) even on error in the event the user wants to maintain backwards
compatibility. I'll be happy to submit another patch for this if there are no
objections.
Previous Comments:
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[2012-04-08 20:51:36] [email protected]
After some further discussion on IRC we agreed that it is best to throw a
warning. The reasoning is as outlined in my previous comment.
The warning is implemented with
https://github.com/php/php-src/commit/7ae93a2c4c8a51cc2aec9977ce3c83c100e382a0.
------------------------------------------------------------------------
[2012-04-08 20:45:41] [email protected]
Automatic comment on behalf of nikic
Revision:
http://git.php.net/?p=php-src.git;a=commit;h=7ae93a2c4c8a51cc2aec9977ce3c83c100e382a0
Log: Fix bug #61660: bin2hex(hex2bin($data)) != $data
------------------------------------------------------------------------
[2012-04-08 16:23:50] theanomaly dot is at gmail dot com
We have no problem type juggling a string to an int as the first
non-whitespace,
non-zero number character...
var_dump(1 + "\t\r\n 0001"); // int(2)
Then, equally, we should have no problem interpreting a hexadecimal
representation of 1 as 01.
:)
------------------------------------------------------------------------
[2012-04-08 16:05:02] [email protected]
> The reason is simple: A padding can be either added on the left or on the
right. E.g. "af52b" could be interpreted both as "0af52b" and as "af52b0".
Why would af52b ever mean af52b0 ? That's like saying 15 could be interpreted
as
150 sometimes.
------------------------------------------------------------------------
[2012-04-08 15:25:52] [email protected]
In my eyes hex2bin should not try to fix the corrupt data by padding it with
zero. Instead it should throw a warning.
The reason is simple: A padding can be either added on the left or on the
right. E.g. "af52b" could be interpreted both as "0af52b" and as "af52b0".
Both are valid interpretations, depending on the use case.
Because of this I think a warning is more appropriate. It signals the user that
the data is wrong. He can always easily fix it by adding a zero to either of
the sides, whatever is more appropriate in his particular situation.
Blindly adding the padding on the other hand will probably be quite unexpected.
Especially when adding the 0 on the left side all the data will be shifted by 4
bits. This means that the whole data will be corrupted. All bytes will change.
(Adding a padding on the right is less intrusive as it only changes one byte).
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the rest of the comments, please view the bug report online at
https://bugs.php.net/bug.php?id=61660
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