freebsd-src/contrib/file/Magdir/cafebabe
2007-05-24 16:12:23 +00:00

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#------------------------------------------------------------------------------
# Cafe Babes unite!
#
# Since Java bytecode and Mach-O fat-files have the same magic number, the test
# must be performed in the same "magic" sequence to get both right. The long
# at offset 4 in a mach-O fat file tells the number of architectures; the short at
# offset 4 in a Java bytecode file is the JVM minor version and the
# short at offset 6 is the JVM major version. Since there are only
# only 18 labeled Mach-O architectures at current, and the first released
# Java class format was version 43.0, we can safely choose any number
# between 18 and 39 to test the number of architectures against
# (and use as a hack). Let's not use 18, because the Mach-O people
# might add another one or two as time goes by...
#
0 belong 0xcafebabe
>4 belong >30 compiled Java class data,
>>6 beshort x version %d.
>>4 beshort x \b%d
>4 belong 1 Mach-O fat file with 1 architecture
>4 belong >1
>>4 belong <20 Mach-O fat file with %ld architectures