This is a bundle of lhf's "Lua byte code inspector" library with the necessary bits from Lua's sources (5.1, 5.2, and 5.3) included to make it build as a standalone rock.
lbci is in the public domain. Lua's source code is available under the MIT license.
http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/#lbci
http://www.lua.org/
For Lua 5.1 a small modification of the lbci code has been done to detect LuaJIT at runtime and bail out with an error.