cafebabe python macosx easter egg?

Chris Rebert clp2 at rebertia.com
Mon Feb 11 07:49:51 CET 2013


On Sun, Feb 10, 2013 at 10:10 PM, Rodrick Brown <rodrick.brown at gmail.com> wrote:
> Subject: cafebabe python macosx easter egg?
>
> $ hexdump -n4 -C $(which python) | awk '{print $2 $3 $4 $5 }'
cafebabe

~ $ # Huh. Let's google...
http://en.wikipedia.org/wiki/Hexspeak :
"0xCAFEBABE ("cafe babe") is used by Mach-O to identify Universal
object files, and by the Java programming language to identify Java
bytecode class files."


Some background:

http://en.wikipedia.org/wiki/Mach-O : "Mach-O […] is a file format for
executables […] used by most systems based on the Mach kernel" (OS X's
kernel is based on the Mach kernel.)

http://en.wikipedia.org/wiki/Universal_binary :
"A universal binary is, in Apple parlance, an executable file or
application bundle that runs natively on either PowerPC or […] Intel
64-based Macintosh computers; it is an implementation of the concept
more generally known as a fat binary."


Confirmation:

"OS X ABI Mach-O File Format Reference":
https://developer.apple.com/library/mac/#documentation/DeveloperTools/Conceptual/MachORuntime/Reference/reference.html
:
struct fat_header
[...]
Fields:
magic
    An integer containing the value 0xCAFEBABE in big-endian byte order format.


So, there you have it. Mach-O and Java bytecode just happen to use the
same magic number. Coincidence.

Cheers,
Chris R.



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