Backport #3297

[patch] Array#pack("i_") is broken in big endian 64bit systems

Added by kkaempf (Klaus Kämpf) about 10 years ago. Updated 10 months ago.



See also for a similar issue (String#unpack("V"))

Array#pack("i_") is broken in big endian 64 bit systems

irb> [1].pack("i_")
=> "\000\000\000\000"

The root cause is similar to the one of issue 1131, use of a wrong offset in a 64bit long.
But the fix is a bit simpler and is probably correct for all other architectures too.

According to the documentation, the "i" format of pack/unpack uses a fixed-size (32bit) integer, while adding "_" uses the system-size.
However, the implementation of Array#pack uses a 'long' type (64bit !) to store an intermediate value, thus breaking OFF() in accessing the wrong 4 bytes of the value.

Fix: Use 'int' to store the intermediate value (use of int is correct for the fixed-size as well as the system-size case) and don't use OFF()

With this patch, the pack_spec and unpack_spec tests of run without issues.


array_pack.patch (584 Bytes) array_pack.patch kkaempf (Klaus Kämpf), 05/15/2010 04:10 AM

Updated by akr (Akira Tanaka) about 10 years ago

OFF* macros are already removed from Ruby 1.8.8.


Updated by shyouhei (Shyouhei Urabe) about 9 years ago

  • Status changed from Open to Feedback

Sorry for this late reply, does this still happen? I guess it has already been fixed for a while.


Updated by jeremyevans0 (Jeremy Evans) 10 months ago

  • Status changed from Feedback to Closed

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