In order for argv[3] to be used, argc needs to be at least 4, not 3.
This bug was found using lgtm.com analyzer:
8c1b2658f8/files/semodule-utils/semodule_package/semodule_unpackage.c?sort=name&dir=ASC&mode=heatmap#xb1ce80b43260d34c:1
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>