From: "Klaus Kämpf" <redmine@...>
Date: 2010-05-10T03:48:23+09:00
Subject: [ruby-core:30121] [Bug #1131] String#unpack("V") does not work correctly is linux on s390x

Issue #1131 has been updated by Klaus K��mpf.

File bnc603914_string_unpack.patch added

unpack("V") broken on all systems with sizeof(long) == 8, ppc64 is also affected.

It is caused by the following code (pack.c, pack_unpack(), case 'V')

                unsigned long tmp = 0;
                memcpy(OFF32(&tmp), s, NATINT_LEN(long,4));
                s += NATINT_LEN(long,4);
                rb_ary_push(ary, ULONG2NUM(vtohl(tmp)));

The use of OFF32 in memcpy copies the int32 value into the correct half of the 8-byte target value (tmp).
The call to vtohl() swaps the complete 8-byte value (acting like swap64), thereby bringing the 4 bytes of the int32
into the right endianess but also into the wrong half of the 8-byte target.

The fix is to either drop of OFF32 call or to replace the vtohl with swap32. I choose the latter since swap32
 is faster than vtohl.

Proposed patch attached
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http://redmine.ruby-lang.org/issues/show/1131

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