fix: recursively unpack nested archives

[mrcjkb]

Scenario:

An older rockspec that does not specify a source.dir and for which the source.url no longer exists:

source = {
    url = "http://www.kyne.com.au/~mark/software/download/lua-cjson-2.1.0.zip",
}

The luarocks src.rock looks like this:

• lua-cjson-2.1.0-1.src.rock
  • lua-cjson-2.1.0-1.rockspec
  • lua-cjson-2.1.0.zip -> contains the directory: lua-cjson-2.1.0 (not specified in the source.dir).

To account for this, we need to recursively unpack the nested source archive and infer the source directory.

[vhyrro]

Code looks great, but this definitely needs a rigorous test harness. I remember implementing this functionality at one point and breaking half the other luarocks packages which didn't want recursive unpacking (I think it was either kong or some openresty package that didn't like this) :/

How hard would it be for us to make a harness that tests rocks compatibility against a large sample of luarocks.org rockspecs? Preferably without bombarding them with get requests every day 😅

[mrcjkb]

I remember implementing this functionality at one point and breaking half the other luarocks packages which didn't want recursive unpacking (I think it was either kong or some openresty package that didn't like this) :/

I just realised your check was already in place, for tar.gz archives only though.
I have modified my PR to use the same flag prevent the recursive unpack call if source.file is set.
Note that the flag is always false when unpacking a .src.rock.