From https://sourceforge.net/p/elftoolchain/tickets/474/
~~~
printf '!<arch>\n%-48s%-10s`\n%-48s%-10s`\n' /tmp/file 0 ../file 0 > test.a
n% ./ar -xv test.a
x - /tmp/file
ar: warning: Absolute path '/tmp/file'
x - ../file
ar: warning: Path contains '..'
~~~