Bug #51275 [Asn->Opn]: unpack('I', $x) on 64 bit big endian unreliable
Edit report at http://bugs.php.net/bug.php?id=51275&edit=1
ID: 51275
Updated by: kalle@php.net
Reported by: stuart_hayton at uk dot ibm dot com
Summary: unpack('I', $x) on 64 bit big endian unreliable
-Status: Assigned
+Status: Open
Type: Bug
Package: Strings related
Operating System: AIX64
PHP Version: 5.3.2
-Assigned To: kalle
+Assigned To:
Block user comment: N
Previous Comments:
------------------------------------------------------------------------
[2010-03-12 04:45:04] kalle@php.net
Hi, could you please upload the patch using diff -u to the bug tracker?
------------------------------------------------------------------------
[2010-03-11 16:20:33] stuart_hayton at uk dot ibm dot com
Description:
------------
Testing unpack 'I' format on a 64bit big-endian architecture.
The result depends on the sign bit in the *next* integer in the packed
buffer
or a out of buffer byte if it is not that long.
A patch which resolves this is below.
I think the code ends up producing identical results for the I and i
format which may be the most desirable thing but the code looks like it
was
intended to behave differently. Maybe it can be simplified.
Similar to bug #40894 but a different format (I).
patch:
*** pack.c Thu Mar 11 15:05:11 2010
--- pack.c.orig Thu Mar 11 15:03:20 2010
***************
*** 752,758 ****
if (type == 'i') {
issigned =
input[inputpos + (machine_little_endian ? (sizeof(int) - 1) : 0)] &
0x80;
! } else if (sizeof(long)
> 4 && input[inputpos + (machine_little_endian ? (sizeof(int) - 1) : 0)]
& 0x80 == 0x80) {
v = ~INT_MAX;
}
--- 752,758 ----
if (type == 'i') {
issigned =
input[inputpos + (machine_little_endian ? (sizeof(int) - 1) : 0)] &
0x80;
! } else if (sizeof(long)
> 4 && (input[inputpos + machine_endian_long_map[3]] & 0x80) == 0x80) {
v = ~INT_MAX;
}
Test script:
---------------
<?php
echo PHP_INT_MAX."\n";
print_r(unpack('I', pack('I', -10000) . pack('I', 10000)));
print_r(unpack('I', pack('I', -10000) . pack('I', -10000)));
?>
Expected result:
----------------
9223372036854775807
Array
(
[1] => -10000
)
Array
(
[1] => -10000
)
Actual result:
--------------
9223372036854775807
Array
(
[1] => 4294957296
)
Array
(
[1] => -10000
)
------------------------------------------------------------------------
--
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