cfg, cmd: major reorganization

* `--lua-dir` flag, specifying a prefix for the Lua installation to
  be used. This reconfigures LuaRocks entirely, including allowing
  a LuaRocks which is itself running using one Lua 5.x version to
  manage packages for a different Lua 5.y version. The resulting
  configuration can be checked with `luarocks config --lua-dir=<path>`.
* requiring `luarocks.core.cfg` no longer has side-effects
  * configuration now needs to be initialized with `cfg.init([lua_data])`,
    where `lua_data` is a table with the configuration of the VM:
    * `lua_version` - e.g. `"5.3"`
    * `luajit_version` - e.g. `"2.1.0-beta3"`
    * `lua_interpreter` - e.g. `"lua5.3"`
    * `lua_bindir` - e.g. `"/usr/local/bin"`
    * `lua_libdir` - e.g. `"/usr/local/lib"`
    * `lua_incdir` - e.g. `"/usr/local/include/lua-5.3"`
  * `cfg.init` can be called multiple times, reconfiguring the global state.
    This is important since `luarocks.loader` now calls it, and the `--lua-dir`
    command line can override the configuration and reconfigure LuaRocks.
* `site_config_*` is no more: LuaRocks is no longer dependent on a properly-written
  site_config file. Instead, it can *optionally* use `luarocks.core.hardcoded`
  for hardcoded values, or detect its configuration at runtime, based on
  OS detection, arg[-1] or command-line flags.
* reduction of moving parts in the configuration:
  * `cfg.platforms` is no longer a globally-visible table; instead, `cfg`
    provides an API of read-only functions: `is_platform`, `each_platform`,
    `print_platforms`.
  * `cfg.*_proxy` options are no longer configured via the config files,
    but rather via the standard `*_proxy` environment variables.
* `"windows"` is now the more general platform name of the Windows family.
  This is technically a breaking change but I don't expect it to cause
  problems with real-world rockspecs.
* internal code reorganization in `luarocks.cmd` module

7 files changed, 963 insertions, 785 deletions

diff --git a/src/luarocks/cmd.lua b/src/luarocks/cmd.lua
index 51d22154..70d93670 100644
--- a/src/luarocks/cmd.lua
+++ b/src/luarocks/cmd.lua
@@ -4,13 +4,13 @@ local cmd = {}
 
 local unpack = unpack or table.unpack
 
-local util = require("luarocks.util")
 local cfg = require("luarocks.core.cfg")
+local util = require("luarocks.util")
 local path = require("luarocks.path")
-local dir = require("luarocks.dir")
 local deps = require("luarocks.deps")
-local fs = require("luarocks.fs")
+local dir = require("luarocks.dir")
 local fun = require("luarocks.fun")
+local fs = require("luarocks.fs")
 
 local program = util.this_program("luarocks")
 
@@ -22,12 +22,6 @@ cmd.errorcodes = {
    CRASH = 99
 }
 
-local function replace_tree(flags, tree)
-   tree = dir.normalize(tree)
-   flags["tree"] = tree
-   path.use_tree(tree)
-end
-
 local function is_ownership_ok(directory)
    local me = fs.current_user()
    for _ = 1,3 do -- try up to grandparent
@@ -40,16 +34,240 @@ local function is_ownership_ok(directory)
    return false
 end
 
-local function find_project_dir()
-   local try = "."
-   for _ = 1, 10 do -- FIXME detect when root dir was hit instead
-      local abs = fs.absolute_name(try)
-      if fs.is_dir(abs .. "/.luarocks") and fs.is_dir(abs .. "/lua_modules") then
-         abs = abs:gsub("/.$", "")
-         return abs, abs .. "/lua_modules"
+do
+   local function check_lua_version(lua_exe, luaver)
+      local luajitver
+      if not (luaver and luaver:match("^[0-9]")) then
+         luaver = util.popen_read(lua_exe .. ' -e "io.write(_VERSION:sub(5))"')
+      end
+      if luaver == "5.1" then
+         luajitver = util.popen_read(lua_exe .. ' -e "io.write(tostring(jit and jit.version:sub(8)))"')
+         if luajitver == "nil" then
+            luajitver = nil
+         end
+      end
+      return luaver, luajitver
+   end
+
+   local function exists(file)
+      local fd = io.open(file, "r")
+      if fd then
+         fd:close()
+         return true
+      end
+      return false
+   end
+
+   local find_lua_bindir
+   do
+      local exe_suffix = (package.config:sub(1, 1) == "\\" and ".exe" or "")
+
+      local function insert_lua_versions(names, luaver)
+         local variants = {
+            "lua" .. luaver .. exe_suffix,
+            "lua" .. luaver:gsub("%.", "") .. exe_suffix,
+            "lua-" .. luaver .. exe_suffix,
+            "lua-" .. luaver:gsub("%.", "") .. exe_suffix,
+         }
+         for _, name in ipairs(variants) do
+            names[name] = luaver
+            table.insert(names, name)
+         end
+      end
+
+      find_lua_bindir = function(prefix, luaver)
+         local names = {}
+         if luaver then
+            insert_lua_versions(names, luaver)
+         else
+            for v in util.lua_versions("descending") do
+               insert_lua_versions(names, v)
+            end
+         end
+         table.insert(names, "lua" .. exe_suffix)
+         table.insert(names, "luajit" .. exe_suffix)
+
+         local bindirs = { prefix .. "/bin", prefix }
+         local tried = {}
+         for _, d in ipairs(bindirs) do
+            for _, name in ipairs(names) do
+               local lua_exe = dir.path(d, name)
+               table.insert(tried, lua_exe)
+               if exists(lua_exe) then
+                  return name, d, luaver
+               end
+            end
+         end
+         return nil, "Lua interpreter not found at " .. prefix .. "\n" ..
+                     "Tried:\t" .. table.concat(tried, "\n\t")
+      end
+   end
+
+   local function find_lua_incdir(prefix, luaver, luajitver)
+      luajitver = luajitver and luajitver:gsub("%-.*", "")
+      local incdirs = {
+         prefix .. "/include",
+         prefix .. "/include/lua/" .. luaver,
+         prefix .. "/include/lua" .. luaver,
+         prefix,
+         luajitver and prefix .. "/include/luajit-" .. luajitver,
+      }
+
+      for _, d in ipairs(incdirs) do
+         local lua_h = dir.path(d, "lua.h")
+         if exists(lua_h) then
+            return d
+         end
+      end
+
+      -- fallback to a default, as it is not necessarily needed.
+      return incdirs[1]
+   end
+
+   find_lua = function(prefix, luaver)
+      local lua_interpreter, bindir
+      lua_interpreter, bindir, luaver = find_lua_bindir(prefix, luaver)
+      if not lua_interpreter then
+         return nil, bindir
+      end
+
+      local luajitver
+      local lua_exe = dir.path(bindir, lua_interpreter)
+      luaver, luajitver = check_lua_version(lua_exe, luaver)
+
+      return {
+         lua_version = luaver,
+         luajit_version = luajitver,
+         lua_interpreter = lua_interpreter,
+         lua_dir = prefix,
+         lua_bindir = bindir,
+         lua_incdir = find_lua_incdir(prefix, luaver, luajitver),
+         lua_libdir = prefix .. "/lib",
+      }
+   end
+end
+
+local function check_popen()
+   local popen_ok, popen_result = pcall(io.popen, "")
+   if popen_ok then
+      if popen_result then
+         popen_result:close()
+      end
+   else
+      io.stderr:write("Your version of Lua does not support io.popen,\n")
+      io.stderr:write("which is required by LuaRocks. Please check your Lua installation.\n")
+      os.exit(cmd.errorcodes.UNSPECIFIED)
+   end
+end
+
+local process_tree_flags
+do
+   local function replace_tree(flags, tree)
+      tree = dir.normalize(tree)
+      flags["tree"] = tree
+      path.use_tree(tree)
+   end
+
+   local function find_project_dir()
+      local try = "."
+      for _ = 1, 10 do -- FIXME detect when root dir was hit instead
+         local abs = fs.absolute_name(try)
+         if fs.is_dir(abs .. "/.luarocks") and fs.is_dir(abs .. "/lua_modules") then
+            abs = abs:gsub("/.$", "")
+            return abs, abs .. "/lua_modules"
+         end
+         try = try .. "/.."
+      end
+   end
+
+   local function strip_trailing_slashes()
+      if type(cfg.root_dir) == "string" then
+        cfg.root_dir = cfg.root_dir:gsub("/+$", "")
+      else
+        cfg.root_dir.root = cfg.root_dir.root:gsub("/+$", "")
+      end
+      cfg.rocks_dir = cfg.rocks_dir:gsub("/+$", "")
+      cfg.deploy_bin_dir = cfg.deploy_bin_dir:gsub("/+$", "")
+      cfg.deploy_lua_dir = cfg.deploy_lua_dir:gsub("/+$", "")
+      cfg.deploy_lib_dir = cfg.deploy_lib_dir:gsub("/+$", "")
+   end
+
+   process_tree_flags = function(flags)
+
+      if cfg.local_by_default then
+         flags["local"] = true
+      end
+
+      if flags["tree"] then
+         local named = false
+         for _, tree in ipairs(cfg.rocks_trees) do
+            if type(tree) == "table" and flags["tree"] == tree.name then
+               if not tree.root then
+                  return nil, "Configuration error: tree '"..tree.name.."' has no 'root' field."
+               end
+               replace_tree(flags, tree.root)
+               named = true
+               break
+            end
+         end
+         if not named then
+            local root_dir = fs.absolute_name(flags["tree"])
+            replace_tree(flags, root_dir)
+         end
+      elseif flags["project-tree"] then
+         local tree = flags["project-tree"]
+         table.insert(cfg.rocks_trees, 1, { name = "project", root = tree } )
+         path.use_tree(tree)
+      elseif flags["local"] then
+         if not cfg.home_tree then
+            return nil, "The --local flag is meant for operating in a user's home directory.\n"..
+               "You are running as a superuser, which is intended for system-wide operation.\n"..
+               "To force using the superuser's home, use --tree explicitly."
+         end
+         replace_tree(flags, cfg.home_tree)
+      else
+         local project_dir, rocks_tree = find_project_dir()
+         if project_dir then
+            table.insert(cfg.rocks_trees, 1, { name = "project", root = rocks_tree } )
+            path.use_tree(rocks_tree)
+         else
+            local trees = cfg.rocks_trees
+            path.use_tree(trees[#trees])
+         end
+      end
+
+      strip_trailing_slashes()
+
+      cfg.variables.ROCKS_TREE = cfg.rocks_dir
+      cfg.variables.SCRIPTS_DIR = cfg.deploy_bin_dir
+
+      return true
+   end
+end
+
+local function process_server_flags(flags)
+   if flags["server"] then
+      local protocol, pathname = dir.split_url(flags["server"])
+      table.insert(cfg.rocks_servers, 1, protocol.."://"..pathname)
+   end
+
+   if flags["dev"] then
+      local append_dev = function(s) return dir.path(s, "dev") end
+      local dev_servers = fun.traverse(cfg.rocks_servers, append_dev)
+      cfg.rocks_servers = fun.concat(dev_servers, cfg.rocks_servers)
+   end
+
+   if flags["only-server"] then
+      if flags["dev"] then
+         return nil, "--only-server cannot be used with --dev"
       end
-      try = try .. "/.."
+      if flags["server"] then
+         return nil, "--only-server cannot be used with --server"
+      end
+      cfg.rocks_servers = { flags["only-server"] }
    end
+
+   return true
 end
 
 --- Main command-line processor.
@@ -58,9 +276,13 @@ end
 -- to it any additional arguments passed by the user.
 -- Uses the global table "commands", which contains
 -- the loaded modules representing commands.
+-- @param program_version string: The program version number as a string.
+-- @param description string: Short summary description of the program.
 -- @param ... string: Arguments given on the command-line.
 function cmd.run_command(description, commands, ...)
 
+   check_popen()
+
    local function error_handler(err)
       return debug.traceback("LuaRocks "..cfg.program_version..
          " bug (please report at https://github.com/luarocks/luarocks/issues).\n"..err, 2)
@@ -82,45 +304,39 @@ function cmd.run_command(description, commands, ...)
       os.exit(exitcode or cmd.errorcodes.UNSPECIFIED)
    end
 
-   local args = {...}
-   local cmdline_vars = {}
-   for i = #args, 1, -1 do
-      local arg = args[i]
-      if arg:match("^[^-][^=]*=") then
-         local var, val = arg:match("^([A-Z_][A-Z0-9_]*)=(.*)")
-         if val then
-            cmdline_vars[var] = val
-            table.remove(args, i)
-         else
-            die("Invalid assignment: "..arg)
+   local function process_arguments(...)
+      local args = {...}
+      local cmdline_vars = {}
+      for i = #args, 1, -1 do
+         local arg = args[i]
+         if arg:match("^[^-][^=]*=") then
+            local var, val = arg:match("^([A-Z_][A-Z0-9_]*)=(.*)")
+            if val then
+               cmdline_vars[var] = val
+               table.remove(args, i)
+            else
+               die("Invalid assignment: "..arg)
+            end
          end
       end
-   end
-   local nonflags = { util.parse_flags(unpack(args)) }
-   local flags = table.remove(nonflags, 1)
-   if flags.ERROR then
-      die(flags.ERROR.." See --help.")
-   end
-   
-   fs.init()
+      local nonflags = { util.parse_flags(unpack(args)) }
+      local flags = table.remove(nonflags, 1)
+      if flags.ERROR then
+         die(flags.ERROR.." See --help.")
+      end
 
-   if flags["from"] then flags["server"] = flags["from"] end
-   if flags["only-from"] then flags["only-server"] = flags["only-from"] end
-   if flags["only-sources-from"] then flags["only-sources"] = flags["only-sources-from"] end
-   if flags["to"] then flags["tree"] = flags["to"] end
-   if flags["nodeps"] then
-      flags["deps-mode"] = "none"
-   end
-   
-   cfg.flags = flags
+      -- Compatibility for old names of some flags
+      if flags["to"] then flags["tree"] = flags["to"] end
+      if flags["from"] then flags["server"] = flags["from"] end
+      if flags["nodeps"] then flags["deps-mode"] = "none" end
+      if flags["only-from"] then flags["only-server"] = flags["only-from"] end
+      if flags["only-sources-from"] then flags["only-sources"] = flags["only-sources-from"] end
 
-   local command
-   
-   if flags["verbose"] then   -- setting it in the config file will kick-in earlier in the process
-      cfg.verbose = true
-      fs.verbose()
+      return flags, nonflags, cmdline_vars
    end
 
+   local flags, nonflags, cmdline_vars = process_arguments(...)
+
    if flags["timeout"] then   -- setting it in the config file will kick-in earlier in the process
       local timeout = tonumber(flags["timeout"])
       if timeout then
@@ -130,6 +346,7 @@ function cmd.run_command(description, commands, ...)
       end
    end
 
+   local command
    if flags["version"] then
       util.printout(program.." "..cfg.program_version)
       util.printout(description)
@@ -141,101 +358,55 @@ function cmd.run_command(description, commands, ...)
       command = table.remove(nonflags, 1)
    end
    command = command:gsub("-", "_")
-   
-   if cfg.local_by_default then
-      flags["local"] = true
-   end
 
    if flags["deps-mode"] and not deps.check_deps_mode_flag(flags["deps-mode"]) then
       die("Invalid entry for --deps-mode.")
    end
-   
-   if flags["tree"] then
-      local named = false
-      for _, tree in ipairs(cfg.rocks_trees) do
-         if type(tree) == "table" and flags["tree"] == tree.name then
-            if not tree.root then
-               die("Configuration error: tree '"..tree.name.."' has no 'root' field.")
-            end
-            replace_tree(flags, tree.root)
-            named = true
-            break
-         end
-      end
-      if not named then
-         local root_dir = fs.absolute_name(flags["tree"])
-         replace_tree(flags, root_dir)
-      end
-   elseif flags["project-tree"] then
-      local tree = flags["project-tree"]
-      table.insert(cfg.rocks_trees, 1, { name = "project", root = tree } )
-      path.use_tree(tree)
-   elseif flags["local"] then
-      if not cfg.home_tree then
-         die("The --local flag is meant for operating in a user's home directory.\n"..
-             "You are running as a superuser, which is intended for system-wide operation.\n"..
-             "To force using the superuser's home, use --tree explicitly.")
-      end
-      replace_tree(flags, cfg.home_tree)
-   else
-      local project_dir, rocks_tree = find_project_dir()
-      if project_dir then
-         table.insert(cfg.rocks_trees, 1, { name = "project", root = rocks_tree } )
-         path.use_tree(rocks_tree)
-      else
-         local trees = cfg.rocks_trees
-         path.use_tree(trees[#trees])
-      end
+
+   local lua_data
+   if flags["lua-dir"] then
+      lua_data = find_lua(flags["lua-dir"], flags["lua-version"])
    end
 
-   if type(cfg.root_dir) == "string" then
-     cfg.root_dir = cfg.root_dir:gsub("/+$", "")
-   else
-     cfg.root_dir.root = cfg.root_dir.root:gsub("/+$", "")
+   -----------------------------------------------------------------------------
+   local ok, err = cfg.init(lua_data, util.warning)
+   if not ok then
+      die(err)
    end
-   cfg.rocks_dir = cfg.rocks_dir:gsub("/+$", "")
-   cfg.deploy_bin_dir = cfg.deploy_bin_dir:gsub("/+$", "")
-   cfg.deploy_lua_dir = cfg.deploy_lua_dir:gsub("/+$", "")
-   cfg.deploy_lib_dir = cfg.deploy_lib_dir:gsub("/+$", "")
-   
-   cfg.variables.ROCKS_TREE = cfg.rocks_dir
-   cfg.variables.SCRIPTS_DIR = cfg.deploy_bin_dir
+   -----------------------------------------------------------------------------
 
-   if flags["server"] then
-      local protocol, pathname = dir.split_url(flags["server"])
-      table.insert(cfg.rocks_servers, 1, protocol.."://"..pathname)
+   fs.init()
+
+   if flags["verbose"] then
+      cfg.verbose = true
+      fs.verbose()
    end
 
-   if flags["dev"] then
-      local append_dev = function(s) return dir.path(s, "dev") end
-      local dev_servers = fun.traverse(cfg.rocks_servers, append_dev)
-      cfg.rocks_servers = fun.concat(dev_servers, cfg.rocks_servers)
+   if (not fs.current_dir()) or fs.current_dir() == "" then
+      die("Current directory does not exist. Please run LuaRocks from an existing directory.")
    end
-   
-   if flags["only-server"] then
-      if flags["dev"] then
-         die("--only-server cannot be used with --dev")
-      end
-      if flags["server"] then
-         die("--only-server cannot be used with --server")
-      end
-      cfg.rocks_servers = { flags["only-server"] }
+
+   local ok, err
+   ok, err = process_tree_flags(flags)
+   if not ok then
+      die(err)
+   end
+
+   ok, err = process_server_flags(flags)
+   if not ok then
+      die(err)
    end
 
    if flags["only-sources"] then
       cfg.only_sources_from = flags["only-sources"]
    end
-  
+
    if command ~= "help" then
       for k, v in pairs(cmdline_vars) do
          cfg.variables[k] = v
       end
    end
 
-   if (not fs.current_dir()) or fs.current_dir() == "" then
-      die("Current directory does not exist. Please run LuaRocks from an existing directory.")
-   end
-
    if not is_ownership_ok(cfg.local_cache) then
       util.warning("The directory '" .. cfg.local_cache .. "' or its parent directory "..
                    "is not owned by the current user and the cache has been disabled. "..
@@ -246,10 +417,16 @@ function cmd.run_command(description, commands, ...)
       cfg.local_cache = fs.make_temp_dir("local_cache")
       util.schedule_function(fs.delete, cfg.local_cache)
    end
-   
+
    if commands[command] then
       local cmd_mod = require(commands[command])
-      local call_ok, ok, err, exitcode = xpcall(function() return cmd_mod.command(flags, unpack(nonflags)) end, error_handler)
+      local call_ok, ok, err, exitcode = xpcall(function()
+         if command == "help" then
+            return cmd_mod.command(description, commands, unpack(nonflags))
+         else
+            return cmd_mod.command(flags, unpack(nonflags))
+         end
+      end, error_handler)
       if not call_ok then
          die(ok, cmd.errorcodes.CRASH)
       elseif not ok then
diff --git a/src/luarocks/cmd/help.lua b/src/luarocks/cmd/help.lua
index 1e1d8676..3b13acc2 100644
--- a/src/luarocks/cmd/help.lua
+++ b/src/luarocks/cmd/help.lua
@@ -63,6 +63,7 @@ function help.command(description, commands, command)
                                (overrides any entries in the config file)
         --only-sources=<url>   Restrict downloads to paths matching the
                                given URL.
+        --lua-dir=<prefix>     Which Lua installation to use.
         --tree=<tree>          Which tree to operate on.
         --local                Use the tree in the user's home directory.
                                To enable it, see ']]..program..[[ help path'.
diff --git a/src/luarocks/core/cfg.lua b/src/luarocks/core/cfg.lua
index 7c29e2dc..cd3aadbc 100644
--- a/src/luarocks/core/cfg.lua
+++ b/src/luarocks/core/cfg.lua
@@ -10,106 +10,19 @@
 -- files. Run `luarocks` with no arguments to see the locations of
 -- these files in your platform.
 
-local rawset, next, table, pairs, require, io, os, setmetatable, pcall, ipairs, package, tonumber, type, assert, _VERSION =
-      rawset, next, table, pairs, require, io, os, setmetatable, pcall, ipairs, package, tonumber, type, assert, _VERSION
-
-local cfg = {}
-
-cfg.lua_version = _VERSION:match(" (5%.[1234])$") or "5.1"
-local version_suffix = cfg.lua_version:gsub("%.", "_")
-
--- Load site-local global configurations
-local ok, site_config = pcall(require, "luarocks.core.site_config_"..version_suffix)
-if not ok then
-   io.stderr:write("Site-local luarocks/core/site_config_"..version_suffix..".lua file not found. Incomplete installation?\n")
-   site_config = {}
-end
+local next, table, pairs, require, os, pcall, ipairs, package, tonumber, type, assert =
+      next, table, pairs, require, os, pcall, ipairs, package, tonumber, type, assert
 
 local util = require("luarocks.core.util")
 local persist = require("luarocks.core.persist")
-local require = nil
---------------------------------------------------------------------------------
 
-cfg.program_version = "dev"
-cfg.program_series = "3.0"
-cfg.major_version = (cfg.program_version:match("([^.]%.[^.])")) or cfg.program_series
-cfg.variables = {}
-cfg.rocks_trees = {}
-cfg.platforms = {}
-
-local popen_ok, popen_result = pcall(io.popen, "")
-if popen_ok then
-   if popen_result then
-      popen_result:close()
-   end
-else
-   io.stderr:write("Your version of Lua does not support io.popen,\n")
-   io.stderr:write("which is required by LuaRocks. Please check your Lua installation.\n")
-   os.exit(1) -- FIXME
-end
+--------------------------------------------------------------------------------
 
--- System detection:
-
--- A proper installation of LuaRocks will hardcode the system
--- and proc values with site_config.LUAROCKS_UNAME_S and site_config.LUAROCKS_UNAME_M,
--- so that this detection does not run every time. When it is
--- performed, we use the Unix way to identify the system,
--- even on Windows (assuming UnxUtils or Cygwin).
-local system = site_config.LUAROCKS_UNAME_S or util.popen_read("uname -s")
-local proc = site_config.LUAROCKS_UNAME_M or util.popen_read("uname -m")
-if proc:match("i[%d]86") then
-   cfg.target_cpu = "x86"
-elseif proc:match("amd64") or proc:match("x86_64") then
-   cfg.target_cpu = "x86_64"
-elseif proc:match("Power Macintosh") then
-   cfg.target_cpu = "powerpc"
- else
-   cfg.target_cpu = proc
-end
+local program_version = "dev"
+local program_series = "3.0"
+local major_version = (program_version:match("([^.]%.[^.])")) or program_series
 
-if system == "FreeBSD" then
-   cfg.platforms.unix = true
-   cfg.platforms.freebsd = true
-   cfg.platforms.bsd = true
-elseif system == "OpenBSD" then
-   cfg.platforms.unix = true
-   cfg.platforms.openbsd = true
-   cfg.platforms.bsd = true
-elseif system == "NetBSD" then
-   cfg.platforms.unix = true
-   cfg.platforms.netbsd = true
-   cfg.platforms.bsd = true
-elseif system == "Darwin" then
-   cfg.platforms.unix = true
-   cfg.platforms.macosx = true
-   cfg.platforms.bsd = true
-elseif system == "Linux" then
-   cfg.platforms.unix = true
-   cfg.platforms.linux = true
-elseif system == "SunOS" then
-   cfg.platforms.unix = true
-   cfg.platforms.solaris = true
-elseif system and system:match("^CYGWIN") then
-   cfg.platforms.unix = true
-   cfg.platforms.cygwin = true
-elseif system and system:match("^MSYS") then
-   cfg.platforms.unix = true
-   cfg.platforms.msys = true
-   cfg.platforms.cygwin = true
-elseif system and system:match("^Windows") then
-   cfg.platforms.windows = true
-   cfg.platforms.win32 = true
-elseif system and system:match("^MINGW") then
-   cfg.platforms.windows = true
-   cfg.platforms.mingw32 = true
-   cfg.platforms.win32 = true
-elseif system == "Haiku" then
-   cfg.platforms.unix = true
-   cfg.platforms.haiku = true
-else
-   cfg.platforms.unix = true
-   -- Fall back to Unix in unknown systems.
-end
+local is_windows = package.config:sub(1,1) == "\\"
 
 -- Set order for platform overrides.
 -- More general platform identifiers should be listed first,
@@ -128,630 +41,719 @@ local platform_order = {
    "msys",
    "haiku",
    -- Windows
+   "windows",
    "win32",
    "mingw32",
-   "windows",
 }
 
--- Path configuration:
-local sys_config_file, home_config_file
-local sys_config_file_default, home_config_file_default
-local sys_config_dir, home_config_dir
-local sys_config_ok, home_config_ok = false, false
-local extra_luarocks_module_dir
-sys_config_dir = site_config.LUAROCKS_SYSCONFDIR or site_config.LUAROCKS_PREFIX
-if cfg.platforms.windows then
-   cfg.home = os.getenv("APPDATA") or "c:"
-   sys_config_dir = sys_config_dir or "c:/luarocks"
-   home_config_dir = cfg.home.."/luarocks"
-   cfg.home_tree = cfg.home.."/luarocks/"
-else
-   cfg.home = os.getenv("HOME") or ""
-   sys_config_dir = sys_config_dir or "/etc/luarocks"
-   home_config_dir = cfg.home.."/.luarocks"
-   cfg.home_tree = (os.getenv("USER") ~= "root") and cfg.home.."/.luarocks/"
-end
+local load_config_file
+do
+   -- Create global environment for the config files;
+   local function env_for_config_file(cfg, platforms)
+      local e
+      e = {
+         home = cfg.home,
+         lua_version = cfg.lua_version,
+         platforms = util.make_shallow_copy(platforms),
+         processor = cfg.target_cpu,   -- remains for compat reasons
+         target_cpu = cfg.target_cpu,  -- replaces `processor`
+         os_getenv = os.getenv,
+         variables = cfg.variables or {},
+         dump_env = function()
+            -- debug function, calling it from a config file will show all
+            -- available globals to that config file
+            print(util.show_table(e, "global environment"))
+         end,
+      }
+      return e
+   end
 
--- Create global environment for the config files;
-local env_for_config_file = function() 
-   local e 
-   e = {
-      home = cfg.home,
-      lua_version = cfg.lua_version,
-      platforms = util.make_shallow_copy(cfg.platforms),
-      processor = cfg.target_cpu,   -- remains for compat reasons
-      target_cpu = cfg.target_cpu,  -- replaces `processor`
-      os_getenv = os.getenv, 
-      dump_env = function()
-         -- debug function, calling it from a config file will show all 
-         -- available globals to that config file
-         print(util.show_table(e, "global environment"))
-      end,
-   }
-   return e
-end
+   -- Merge values from config files read into the `cfg` table
+   local function merge_overrides(cfg, overrides)
+      -- remove some stuff we do not want to integrate
+      overrides.os_getenv = nil
+      overrides.dump_env = nil
+      -- remove tables to be copied verbatim instead of deeply merged
+      if overrides.rocks_trees   then cfg.rocks_trees   = nil end
+      if overrides.rocks_servers then cfg.rocks_servers = nil end
+      -- perform actual merge
+      util.deep_merge(cfg, overrides)
+   end
+
+   local function update_platforms(platforms, overrides)
+      if overrides[1] then
+         for k, _ in pairs(platforms) do
+            platforms[k] = nil
+         end
+         for _, v in ipairs(overrides) do
+            platforms[v] = true
+         end
+         -- set some fallback default in case the user provides an incomplete configuration.
+         -- LuaRocks expects a set of defaults to be available.
+         if not (platforms.unix or platforms.windows) then
+            platforms[is_windows and "windows" or "unix"] = true
+         end
+      end
+   end
 
--- Merge values from config files read into the `cfg` table
-local merge_overrides = function(overrides)
-   -- remove some stuff we do not want to integrate
-   overrides.os_getenv = nil
-   overrides.dump_env = nil
-   -- remove tables to be copied verbatim instead of deeply merged
-   if overrides.rocks_trees   then cfg.rocks_trees   = nil end
-   if overrides.rocks_servers then cfg.rocks_servers = nil end
-   -- perform actual merge
-   util.deep_merge(cfg, overrides)
+   -- Load config file and merge its contents into the `cfg` module table.
+   -- @return filepath of succesfully loaded file or nil if it failed
+   load_config_file = function(cfg, platforms, filepath)
+      local result, err, errcode = persist.load_into_table(filepath, env_for_config_file(cfg, platforms))
+      if (not result) and errcode ~= "open" then
+         -- errcode is either "load" or "run"; bad config file, so error out
+         return nil, err, "config"
+      end
+      if result then
+         -- success in loading and running, merge contents and exit
+         update_platforms(platforms, result.platforms)
+         result.platforms = nil
+         merge_overrides(cfg, result)
+         return filepath
+      end
+      return nil -- nothing was loaded
+   end
 end
 
--- Load config file and merge its contents into the `cfg` module table.
--- @return filepath of succesfully loaded file or nil if it failed
-local load_config_file = function(filepath)
-   local result, err, errcode = persist.load_into_table(filepath, env_for_config_file())
-   if (not result) and errcode ~= "open" then
-      -- errcode is either "load" or "run"; bad config file, so error out
-      io.stderr:write(err.."\n")
-      os.exit(3) -- FIXME
-   end
-   if result then
-      -- success in loading and running, merge contents and exit
-      merge_overrides(result)
-      return filepath
-   end
-   return nil -- nothing was loaded
+local function make_platforms(system)
+   if system then
+      if system == "Linux"            then return { unix = true, linux = true }
+      elseif system == "FreeBSD"      then return { unix = true, bsd = true, freebsd = true }
+      elseif system == "OpenBSD"      then return { unix = true, bsd = true, openbsd = true }
+      elseif system == "NetBSD"       then return { unix = true, bsd = true, netbsd = true }
+      elseif system == "Darwin"       then return { unix = true, bsd = true, macosx = true, macos = true }
+      elseif system == "SunOS"        then return { unix = true, solaris = true }
+      elseif system == "Haiku"        then return { unix = true, haiku = true }
+      elseif system:match("^CYGWIN")  then return { unix = true, cygwin = true }
+      elseif system:match("^MSYS")    then return { unix = true, cygwin = true, msys = true }
+      elseif system:match("^Windows") then return { windows = true, win32 = true }
+      elseif system:match("^MINGW")   then return { windows = true, win32 = true, mingw32 = true, mingw = true }
+      end
+   end
+   return { unix = true } -- fallback to Unix in unknown systems
 end
 
+--------------------------------------------------------------------------------
 
--- Load system configuration file
-do 
-   sys_config_file_default = sys_config_dir.."/config-"..cfg.lua_version..".lua"
-   sys_config_file = load_config_file(
-      site_config.LUAROCKS_SYSCONFIG or sys_config_file_default
-   )
-   sys_config_ok = (sys_config_file ~= nil)
-end
+local function make_defaults(lua_version, target_cpu, platforms, home)
+
+   -- Configure defaults:
+   local defaults = {
+
+      lua_interpreter = "lua",
+      local_by_default = false,
+      accept_unknown_fields = false,
+      fs_use_modules = true,
+      hooks_enabled = true,
+      deps_mode = "one",
+      check_certificates = false,
+
+      lua_modules_path = "/share/lua/"..lua_version,
+      lib_modules_path = "/lib/lua/"..lua_version,
+      rocks_subdir = "/lib/luarocks/rocks-"..lua_version,
+
+      arch = "unknown",
+      lib_extension = "unknown",
+      obj_extension = "unknown",
+      link_lua_explicitly = false,
+
+      rocks_servers = {
+         {
+           "https://luarocks.org",
+           "https://raw.githubusercontent.com/rocks-moonscript-org/moonrocks-mirror/master/",
+           "http://luafr.org/moonrocks/",
+           "http://luarocks.logiceditor.com/rocks",
+         }
+      },
+      disabled_servers = {},
 
--- Load user configuration file (if allowed)
-if not site_config.LUAROCKS_FORCE_CONFIG then
-  
-   home_config_file_default = home_config_dir.."/config-"..cfg.lua_version..".lua"
-   
-   local config_env_var   = "LUAROCKS_CONFIG_" .. version_suffix
-   local config_env_value = os.getenv(config_env_var)
-   if not config_env_value then
-      config_env_var   = "LUAROCKS_CONFIG"
-      config_env_value = os.getenv(config_env_var)
-   end
-   
-   -- first try environment provided file, so we can explicitly warn when it is missing
-   if config_env_value then 
-      home_config_file = load_config_file(config_env_value)
-      home_config_ok = (home_config_file ~= nil)
-      if not home_config_ok then
-         io.stderr:write("Warning: could not load configuration file `"..config_env_value.."` given in environment variable "..config_env_var.."\n")
+      upload = {
+         server = "https://luarocks.org",
+         tool_version = "1.0.0",
+         api_version = "1",
+      },
+
+      lua_extension = "lua",
+      connection_timeout = 30,  -- 0 = no timeout
+
+      variables = {
+         MAKE = "make",
+         CC = "cc",
+         LD = "ld",
+         AR = "ar",
+         RANLIB = "ranlib",
+
+         CVS = "cvs",
+         GIT = "git",
+         SSCM = "sscm",
+         SVN = "svn",
+         HG = "hg",
+
+         RSYNC = "rsync",
+         WGET = "wget",
+         SCP = "scp",
+         CURL = "curl",
+
+         PWD = "pwd",
+         MKDIR = "mkdir",
+         RMDIR = "rmdir",
+         CP = "cp",
+         LS = "ls",
+         RM = "rm",
+         FIND = "find",
+         TEST = "test",
+         CHMOD = "chmod",
+         ICACLS = "icacls",
+         MKTEMP = "mktemp",
+
+         ZIP = "zip",
+         UNZIP = "unzip -n",
+         GUNZIP = "gunzip",
+         BUNZIP2 = "bunzip2",
+         TAR = "tar",
+
+         MD5SUM = "md5sum",
+         OPENSSL = "openssl",
+         MD5 = "md5",
+         STAT = "stat",
+         TOUCH = "touch",
+
+         CMAKE = "cmake",
+         SEVENZ = "7z",
+
+         RSYNCFLAGS = "--exclude=.git -Oavz",
+         STATPERMFLAG = "-c '%a'",
+         STATOWNERFLAG = "-c '%U'",
+         CURLNOCERTFLAG = "",
+         WGETNOCERTFLAG = "",
+      },
+
+      external_deps_subdirs = {
+         bin = "bin",
+         lib = "lib",
+         include = "include"
+      },
+      runtime_external_deps_subdirs = {
+         bin = "bin",
+         lib = "lib",
+         include = "include"
+      },
+   }
+
+   if platforms.windows then
+
+      defaults.arch = "win32-"..target_cpu
+      defaults.lib_extension = "dll"
+      defaults.external_lib_extension = "dll"
+      defaults.static_lib_extension = "lib"
+      defaults.obj_extension = "obj"
+      defaults.external_deps_dirs = { "c:/external/", "c:/windows/system32" }
+
+      defaults.makefile = "Makefile.win"
+      defaults.variables.MAKE = "nmake"
+      defaults.variables.CC = "cl"
+      defaults.variables.RC = "rc"
+      defaults.variables.LD = "link"
+      defaults.variables.MT = "mt"
+      defaults.variables.AR = "lib"
+      defaults.variables.LUALIB = "lua"..lua_version..".lib"
+      defaults.variables.CFLAGS = "/nologo /MD /O2"
+      defaults.variables.LIBFLAG = "/nologo /dll"
+
+      defaults.variables.LUA_DIR = "c:/lua"
+      defaults.variables.LUA_BINDIR = "c:/lua/bin"
+      defaults.variables.LUA_LIBDIR = "c:/lua/lib"
+      defaults.variables.LUA_INCDIR = "c:/lua/include"
+
+      defaults.external_deps_patterns = {
+         bin = { "?.exe", "?.bat" },
+         lib = { "?.lib", "?.dll", "lib?.dll" },
+         include = { "?.h" }
+      }
+      defaults.runtime_external_deps_patterns = {
+         bin = { "?.exe", "?.bat" },
+         lib = { "?.dll", "lib?.dll" },
+         include = { "?.h" }
+      }
+      defaults.export_path_separator = ";"
+      defaults.wrapper_suffix = ".bat"
+
+      local localappdata = os.getenv("LOCALAPPDATA")
+      if not localappdata then
+         -- for Windows versions below Vista
+         localappdata = os.getenv("USERPROFILE").."/Local Settings/Application Data"
       end
+      defaults.local_cache = localappdata.."/LuaRocks/Cache"
+      defaults.web_browser = "start"
+
+      defaults.external_deps_subdirs.lib = { "", "lib" }
+      defaults.runtime_external_deps_subdirs.lib = { "", "lib" }
    end
 
-   -- try the alternative defaults if there was no environment specified file or it didn't work
-   if not home_config_ok then
-      home_config_file = load_config_file(home_config_file_default)
-      home_config_ok = (home_config_file ~= nil)
+   if platforms.mingw32 then
+      defaults.obj_extension = "o"
+      defaults.static_lib_extension = "a"
+      defaults.external_deps_dirs = { "c:/external/", "c:/mingw", "c:/windows/system32" }
+      defaults.cmake_generator = "MinGW Makefiles"
+      defaults.variables.MAKE = "mingw32-make"
+      defaults.variables.CC = "mingw32-gcc"
+      defaults.variables.RC = "windres"
+      defaults.variables.LD = "mingw32-gcc"
+      defaults.variables.AR = "ar"
+      defaults.variables.RANLIB = "ranlib"
+      defaults.variables.CFLAGS = "-O2"
+      defaults.variables.LIBFLAG = "-shared"
+      defaults.makefile = "Makefile"
+      defaults.external_deps_patterns = {
+         bin = { "?.exe", "?.bat" },
+         -- mingw lookup list from http://stackoverflow.com/a/15853231/1793220
+         -- ...should we keep ?.lib at the end? It's not in the above list.
+         lib = { "lib?.dll.a", "?.dll.a", "lib?.a", "cyg?.dll", "lib?.dll", "?.dll", "?.lib" },
+         include = { "?.h" }
+      }
+      defaults.runtime_external_deps_patterns = {
+         bin = { "?.exe", "?.bat" },
+         lib = { "cyg?.dll", "?.dll", "lib?.dll" },
+         include = { "?.h" }
+      }
    end
-end
 
+   if platforms.unix then
+      defaults.lib_extension = "so"
+      defaults.static_lib_extension = "a"
+      defaults.external_lib_extension = "so"
+      defaults.obj_extension = "o"
+      defaults.external_deps_dirs = { "/usr/local", "/usr" }
+      defaults.variables.CFLAGS = "-O2"
+      defaults.cmake_generator = "Unix Makefiles"
+      defaults.variables.CC = "gcc"
+      defaults.variables.LD = "gcc"
+      defaults.gcc_rpath = true
+      defaults.variables.LIBFLAG = "-shared"
+
+      defaults.variables.LUA_DIR = "/usr/local"
+      defaults.variables.LUA_BINDIR = "/usr/local/bin"
+      defaults.variables.LUA_LIBDIR = "/usr/local/lib"
+      defaults.variables.LUA_INCDIR = "/usr/local/include"
+
+      defaults.external_deps_patterns = {
+         bin = { "?" },
+         lib = { "lib?.a", "lib?.so", "lib?.so.*" },
+         include = { "?.h" }
+      }
+      defaults.runtime_external_deps_patterns = {
+         bin = { "?" },
+         lib = { "lib?.so", "lib?.so.*" },
+         include = { "?.h" }
+      }
+      defaults.export_path_separator = ":"
+      defaults.wrapper_suffix = ""
+      defaults.local_cache = home.."/.cache/luarocks"
+      if not defaults.variables.CFLAGS:match("-fPIC") then
+         defaults.variables.CFLAGS = defaults.variables.CFLAGS.." -fPIC"
+      end
+      defaults.web_browser = "xdg-open"
+   end
 
-if not next(cfg.rocks_trees) then
-   if cfg.home_tree then
-      table.insert(cfg.rocks_trees, { name = "user", root = cfg.home_tree } )
+   if platforms.cygwin then
+      defaults.lib_extension = "so" -- can be overridden in the config file for mingw builds
+      defaults.arch = "cygwin-"..target_cpu
+      defaults.cmake_generator = "Unix Makefiles"
+      defaults.variables.CC = "echo -llua | xargs gcc"
+      defaults.variables.LD = "echo -llua | xargs gcc"
+      defaults.variables.LIBFLAG = "-shared"
+      defaults.link_lua_explicitly = true
    end
-   if site_config.LUAROCKS_ROCKS_TREE then
-      table.insert(cfg.rocks_trees, { name = "system", root = site_config.LUAROCKS_ROCKS_TREE } )
+
+   if platforms.msys then
+      -- msys is basically cygwin made out of mingw, meaning the subsytem is unixish
+      -- enough, yet we can freely mix with native win32
+      defaults.external_deps_patterns = {
+         bin = { "?.exe", "?.bat", "?" },
+         lib = { "lib?.so", "lib?.so.*", "lib?.dll.a", "?.dll.a",
+                 "lib?.a", "lib?.dll", "?.dll", "?.lib" },
+         include = { "?.h" }
+      }
+      defaults.runtime_external_deps_patterns = {
+         bin = { "?.exe", "?.bat" },
+         lib = { "lib?.so", "?.dll", "lib?.dll" },
+         include = { "?.h" }
+      }
    end
-end
 
--- update platforms list; keyed -> array
-do
-   -- if explicitly given by user,
-   if cfg.platforms[1] then
-      local is_windows = cfg.platforms.windows
-      -- Clear auto-detected values
-      for k, _ in pairs(cfg.platforms) do
-         if type(k) == "string" then
-            cfg.platforms[k] = nil
-         end
-      end
-      -- and set the ones given by the user.
-      for _, plat in ipairs(cfg.platforms) do
-         cfg.platforms[plat] = true
-      end
-      -- If no major platform family was set by the user,
-      if not (cfg.platforms.unix or cfg.platforms.windows) then
-         -- set some fallback defaults in case the user provides an incomplete configuration.
-         -- LuaRocks expects a set of defaults to be available.
-         -- This is used for setting defaults here only; the platform overrides
-         -- will use only the user's list.
-         if is_windows then
-            cfg.platforms.windows = true
-            table.insert(cfg.platforms, "windows")
-         else
-            cfg.platforms.unix = true
-            table.insert(cfg.platforms, "unix")
-         end
-      end
-   else
-      -- Sort detected platform defaults
-      local order = {}
-      for i, v in ipairs(platform_order) do
-         order[v] = i
-      end
-      local entries = {}
-      for k, v in pairs(cfg.platforms) do
-         if type(k) == "string" and v == true then
-            table.insert(entries, k)
-         end
+   if platforms.bsd then
+      defaults.variables.MAKE = "gmake"
+      defaults.variables.STATPERMFLAG = "-f '%OLp'"
+      defaults.variables.STATOWNERFLAG = "-f '%Su'"
+   end
+
+   if platforms.macosx then
+      defaults.variables.MAKE = "make"
+      defaults.external_lib_extension = "dylib"
+      defaults.arch = "macosx-"..target_cpu
+      defaults.variables.LIBFLAG = "-bundle -undefined dynamic_lookup -all_load"
+      defaults.variables.STAT = "/usr/bin/stat"
+      defaults.variables.STATFLAG = "-f '%A'"
+      local version = util.popen_read("sw_vers -productVersion")
+      version = tonumber(version and version:match("^[^.]+%.([^.]+)")) or 3
+      if version >= 10 then
+         version = 8
+      elseif version >= 5 then
+         version = 5
+      else
+         defaults.gcc_rpath = false
       end
-      table.sort(entries, function(a, b) return order[a] < order[b] end)
-      util.deep_merge(cfg.platforms, entries)
+      defaults.variables.CC = "env MACOSX_DEPLOYMENT_TARGET=10."..version.." gcc"
+      defaults.variables.LD = "env MACOSX_DEPLOYMENT_TARGET=10."..version.." gcc"
+      defaults.web_browser = "open"
    end
-end
 
--- Configure defaults:
-local defaults = {
-
-   local_by_default = false,
-   accept_unknown_fields = false,
-   fs_use_modules = true,
-   hooks_enabled = true,
-   deps_mode = "one",
-   check_certificates = false,
-
-   lua_modules_path = "/share/lua/"..cfg.lua_version,
-   lib_modules_path = "/lib/lua/"..cfg.lua_version,
-   rocks_subdir = "/lib/luarocks/rocks-"..cfg.lua_version,
-
-   arch = "unknown",
-   lib_extension = "unknown",
-   obj_extension = "unknown",
-   link_lua_explicitly = false,
-
-   rocks_servers = {
-      {
-        "https://luarocks.org",
-        "https://raw.githubusercontent.com/rocks-moonscript-org/moonrocks-mirror/master/",
-        "http://luafr.org/moonrocks/",
-        "http://luarocks.logiceditor.com/rocks",
-      }
-   },
-   disabled_servers = {},
-
-   upload = {
-      server = "https://luarocks.org",
-      tool_version = "1.0.0",
-      api_version = "1",
-   },
-
-   lua_extension = "lua",
-   lua_interpreter = site_config.LUA_INTERPRETER or "lua",
-   downloader = site_config.LUAROCKS_DOWNLOADER or "wget",
-   md5checker = site_config.LUAROCKS_MD5CHECKER or "md5sum",
-   connection_timeout = 30,  -- 0 = no timeout
-
-   variables = {
-      MAKE = "make",
-      CC = "cc",
-      LD = "ld",
-      AR = "ar",
-      RANLIB = "ranlib",
-
-      CVS = "cvs",
-      GIT = "git",
-      SSCM = "sscm",
-      SVN = "svn",
-      HG = "hg",
-
-      RSYNC = "rsync",
-      WGET = "wget",
-      SCP = "scp",
-      CURL = "curl",
-
-      PWD = "pwd",
-      MKDIR = "mkdir",
-      RMDIR = "rmdir",
-      CP = "cp",
-      LS = "ls",
-      RM = "rm",
-      FIND = "find",
-      TEST = "test",
-      CHMOD = "chmod",
-      ICACLS = "icacls",
-      MKTEMP = "mktemp",
-
-      ZIP = "zip",
-      UNZIP = "unzip -n",
-      GUNZIP = "gunzip",
-      BUNZIP2 = "bunzip2",
-      TAR = "tar",
-
-      MD5SUM = "md5sum",
-      OPENSSL = "openssl",
-      MD5 = "md5",
-      STAT = "stat",
-      TOUCH = "touch",
-
-      CMAKE = "cmake",
-      SEVENZ = "7z",
-
-      RSYNCFLAGS = "--exclude=.git -Oavz",
-      STATPERMFLAG = "-c '%a'",
-      STATOWNERFLAG = "-c '%U'",
-      CURLNOCERTFLAG = "",
-      WGETNOCERTFLAG = "",
-   },
-
-   external_deps_subdirs = site_config.LUAROCKS_EXTERNAL_DEPS_SUBDIRS or {
-      bin = "bin",
-      lib = "lib",
-      include = "include"
-   },
-   runtime_external_deps_subdirs = site_config.LUAROCKS_RUNTIME_EXTERNAL_DEPS_SUBDIRS or {
-      bin = "bin",
-      lib = "lib",
-      include = "include"
-   },
-
-   rocks_provided = {},
-   rocks_provided_3_0 = {},
-}
+   if platforms.linux then
+      defaults.arch = "linux-"..target_cpu
 
-if cfg.platforms.windows then
-   local full_prefix = (site_config.LUAROCKS_PREFIX or (os.getenv("PROGRAMFILES")..[[\LuaRocks]]))
-   extra_luarocks_module_dir = full_prefix.."/lua/?.lua"
-
-   home_config_file = home_config_file and home_config_file:gsub("\\","/")
-   defaults.fs_use_modules = false
-   defaults.arch = "win32-"..cfg.target_cpu 
-   defaults.lib_extension = "dll"
-   defaults.external_lib_extension = "dll"
-   defaults.static_lib_extension = "lib"
-   defaults.obj_extension = "obj"
-   defaults.external_deps_dirs = { "c:/external", "c:/windows/system32" }
-   defaults.variables.LUA_BINDIR = site_config.LUA_BINDIR and site_config.LUA_BINDIR:gsub("\\", "/") or "c:/lua"..cfg.lua_version.."/bin"
-   defaults.variables.LUA_INCDIR = site_config.LUA_INCDIR and site_config.LUA_INCDIR:gsub("\\", "/") or "c:/lua"..cfg.lua_version.."/include"
-   defaults.variables.LUA_LIBDIR = site_config.LUA_LIBDIR and site_config.LUA_LIBDIR:gsub("\\", "/") or "c:/lua"..cfg.lua_version.."/lib"
-
-   defaults.makefile = "Makefile.win"
-   defaults.variables.MAKE = "nmake"
-   defaults.variables.CC = "cl"
-   defaults.variables.RC = "rc"
-   defaults.variables.WRAPPER = full_prefix.."\\rclauncher.c"
-   defaults.variables.LD = "link"
-   defaults.variables.MT = "mt"
-   defaults.variables.AR = "lib"
-   defaults.variables.LUALIB = "lua"..cfg.lua_version..".lib"
-   defaults.variables.CFLAGS = "/nologo /MD /O2"
-   defaults.variables.LIBFLAG = "/nologo /dll"
-
-   local bins = { "SEVENZ", "CP", "FIND", "LS", "MD5SUM",
-      "MKDIR", "MV", "PWD", "RMDIR", "TEST", "UNAME", "WGET" }
-   for _, var in ipairs(bins) do
-      if defaults.variables[var] then
-         defaults.variables[var] = full_prefix.."\\tools\\"..defaults.variables[var]
+      local gcc_arch = util.popen_read("gcc -print-multiarch 2>/dev/null")
+      if gcc_arch and gcc_arch ~= "" then
+         defaults.external_deps_subdirs.lib = { "lib", "lib/" .. gcc_arch, "lib64" }
+         defaults.runtime_external_deps_subdirs.lib = { "lib", "lib/" .. gcc_arch, "lib64" }
+      else
+         defaults.external_deps_subdirs.lib = { "lib", "lib64" }
+         defaults.runtime_external_deps_subdirs.lib = { "lib", "lib64" }
       end
    end
 
-   defaults.external_deps_patterns = {
-      bin = { "?.exe", "?.bat" },
-      lib = { "?.lib", "?.dll", "lib?.dll" },
-      include = { "?.h" }
-   }
-   defaults.runtime_external_deps_patterns = {
-      bin = { "?.exe", "?.bat" },
-      lib = { "?.dll", "lib?.dll" },
-      include = { "?.h" }
-   }
-   defaults.export_path_separator = ";"
-   defaults.wrapper_suffix = ".bat"
-
-   local localappdata = os.getenv("LOCALAPPDATA")
-   if not localappdata then
-      -- for Windows versions below Vista
-      localappdata = os.getenv("USERPROFILE").."/Local Settings/Application Data"
+   if platforms.freebsd then
+      defaults.arch = "freebsd-"..target_cpu
+      defaults.gcc_rpath = false
+      defaults.variables.CC = "cc"
+      defaults.variables.LD = "cc"
    end
-   defaults.local_cache = localappdata.."/LuaRocks/Cache"
-   defaults.web_browser = "start"
 
-   defaults.external_deps_subdirs = site_config.LUAROCKS_EXTERNAL_DEPS_SUBDIRS or {
-      bin = {".", "bin"},
-      lib = {".", "lib"},
-      include = {".", "include"},
-   }
-   defaults.runtime_external_deps_subdirs = site_config.LUAROCKS_RUNTIME_EXTERNAL_DEPS_SUBDIRS or {
-      bin = {".", "bin"},
-      lib = {".", "lib"},
-      include = {".", "include"},
-   }
+   if platforms.openbsd then
+      defaults.arch = "openbsd-"..target_cpu
+   end
 
-end
+   if platforms.netbsd then
+      defaults.arch = "netbsd-"..target_cpu
+   end
 
-if cfg.platforms.mingw32 then
-   defaults.obj_extension = "o"
-   defaults.static_lib_extension = "a"
-   defaults.cmake_generator = "MinGW Makefiles"
-   defaults.variables.MAKE = "mingw32-make"
-   defaults.variables.CC = "mingw32-gcc"
-   defaults.variables.RC = "windres"
-   defaults.variables.LD = "mingw32-gcc"
-   defaults.variables.AR = "ar"
-   defaults.variables.RANLIB = "ranlib"
-   defaults.variables.CFLAGS = "-O2"
-   defaults.variables.LIBFLAG = "-shared"
-   defaults.makefile = "Makefile"
-   defaults.external_deps_dirs = { "c:/external", "c:/mingw", "c:/windows/system32" }
-   defaults.external_deps_patterns = {
-      bin = { "?.exe", "?.bat" },
-      -- mingw lookup list from http://stackoverflow.com/a/15853231/1793220
-      -- ...should we keep ?.lib at the end? It's not in the above list.
-      lib = { "lib?.dll.a", "?.dll.a", "lib?.a", "cyg?.dll", "lib?.dll", "?.dll", "?.lib" },
-      include = { "?.h" }
-   }
-   defaults.runtime_external_deps_patterns = {
-      bin = { "?.exe", "?.bat" },
-      lib = { "cyg?.dll", "?.dll", "lib?.dll" },
-      include = { "?.h" }
-   }
+   if platforms.solaris then
+      defaults.arch = "solaris-"..target_cpu
+      --defaults.platforms = {"unix", "solaris"}
+      defaults.variables.MAKE = "gmake"
+   end
 
-end
+   -- Expose some more values detected by LuaRocks for use by rockspec authors.
+   defaults.variables.LIB_EXTENSION = defaults.lib_extension
+   defaults.variables.OBJ_EXTENSION = defaults.obj_extension
 
-if cfg.platforms.unix then
-   defaults.lib_extension = "so"
-   defaults.static_lib_extension = "a"
-   defaults.external_lib_extension = "so"
-   defaults.obj_extension = "o"
-   defaults.external_deps_dirs = { "/usr/local", "/usr" }
-   defaults.variables.LUA_BINDIR = site_config.LUA_BINDIR or "/usr/local/bin"
-   defaults.variables.LUA_INCDIR = site_config.LUA_INCDIR or "/usr/local/include"
-   defaults.variables.LUA_LIBDIR = site_config.LUA_LIBDIR or "/usr/local/lib"
-   defaults.variables.CFLAGS = "-O2"
-   defaults.cmake_generator = "Unix Makefiles"
-   defaults.variables.CC = "gcc"
-   defaults.variables.LD = "gcc"
-   defaults.gcc_rpath = true
-   defaults.variables.LIBFLAG = "-shared"
-   defaults.external_deps_patterns = {
-      bin = { "?" },
-      lib = { "lib?.a", "lib?.so", "lib?.so.*" },
-      include = { "?.h" }
-   }
-   defaults.runtime_external_deps_patterns = {
-      bin = { "?" },
-      lib = { "lib?.so", "lib?.so.*" },
-      include = { "?.h" }
-   }
-   defaults.export_path_separator = ":"
-   defaults.wrapper_suffix = ""
-   defaults.local_cache = cfg.home.."/.cache/luarocks"
-   if not defaults.variables.CFLAGS:match("-fPIC") then
-      defaults.variables.CFLAGS = defaults.variables.CFLAGS.." -fPIC"
-   end
-   defaults.web_browser = "xdg-open"
+   return defaults
 end
 
-if cfg.platforms.cygwin then
-   defaults.lib_extension = "so" -- can be overridden in the config file for mingw builds
-   defaults.arch = "cygwin-"..cfg.target_cpu
-   defaults.cmake_generator = "Unix Makefiles"
-   defaults.variables.CC = "echo -llua | xargs gcc"
-   defaults.variables.LD = "echo -llua | xargs gcc"
-   defaults.variables.LIBFLAG = "-shared"
-   defaults.link_lua_explicitly = true
-end
+local function make_rocks_provided(lua_version, luajit_version)
+   local rocks_provided = {}
+   local rocks_provided_3_0 = {}
 
-if cfg.platforms.msys then
-   -- msys is basically cygwin made out of mingw, meaning the subsytem is unixish
-   -- enough, yet we can freely mix with native win32
-   defaults.external_deps_patterns = {
-      bin = { "?.exe", "?.bat", "?" },
-      lib = { "lib?.so", "lib?.so.*", "lib?.dll.a", "?.dll.a",
-              "lib?.a", "lib?.dll", "?.dll", "?.lib" },
-      include = { "?.h" }
-   }
-   defaults.runtime_external_deps_patterns = {
-      bin = { "?.exe", "?.bat" },
-      lib = { "lib?.so", "?.dll", "lib?.dll" },
-      include = { "?.h" }
-   }
-end
+   rocks_provided["lua"] = lua_version.."-1"
 
+   if lua_version == "5.2" or lua_version == "5.3" then
+      rocks_provided["bit32"] = lua_version.."-1"
+   end
 
-if cfg.platforms.bsd then
-   defaults.variables.MAKE = "gmake"
-   defaults.variables.STATPERMFLAG = "-f '%OLp'"
-   defaults.variables.STATOWNERFLAG = "-f '%Su'"
-end
+   if lua_version == "5.3" or lua_version == "5.4" then
+      rocks_provided["utf8"] = lua_version.."-1"
+   end
 
-if cfg.platforms.macosx then
-   defaults.variables.MAKE = "make"
-   defaults.external_lib_extension = "dylib"
-   defaults.arch = "macosx-"..cfg.target_cpu
-   defaults.variables.LIBFLAG = "-bundle -undefined dynamic_lookup -all_load"
-   defaults.variables.STAT = "/usr/bin/stat"
-   defaults.variables.STATFLAG = "-f '%A'"
-   local version = util.popen_read("sw_vers -productVersion")
-   version = tonumber(version and version:match("^[^.]+%.([^.]+)")) or 3
-   if version >= 10 then
-      version = 8
-   elseif version >= 5 then
-      version = 5
-   else
-      defaults.gcc_rpath = false
+   if luajit_version then
+      rocks_provided["luabitop"] = luajit_version.."-1"
+      rocks_provided_3_0["luajit"] = luajit_version.."-1"
    end
-   defaults.variables.CC = "env MACOSX_DEPLOYMENT_TARGET=10."..version.." gcc"
-   defaults.variables.LD = "env MACOSX_DEPLOYMENT_TARGET=10."..version.." gcc"
-   defaults.web_browser = "open"
-end
 
-if cfg.platforms.linux then
-   defaults.arch = "linux-"..cfg.target_cpu
+   return rocks_provided, rocks_provided_3_0
 end
 
-if cfg.platforms.freebsd then
-   defaults.arch = "freebsd-"..cfg.target_cpu
-   defaults.gcc_rpath = false
-   defaults.variables.CC = "cc"
-   defaults.variables.LD = "cc"
-end
+local function use_defaults(cfg, defaults)
 
-if cfg.platforms.openbsd then
-   defaults.arch = "openbsd-"..cfg.target_cpu
-end
+   -- Populate some arrays with values from their 'defaults' counterparts
+   -- if they were not already set by user.
+   for _, entry in ipairs({"variables", "rocks_provided"}) do
+      if not cfg[entry] then
+         cfg[entry] = {}
+      end
+      for k,v in pairs(defaults[entry]) do
+         if not cfg[entry][k] then
+            cfg[entry][k] = v
+         end
+      end
+   end
+   util.deep_merge_under(defaults.rocks_provided_3_0, cfg.rocks_provided)
 
-if cfg.platforms.netbsd then
-   defaults.arch = "netbsd-"..cfg.target_cpu
-end
+   util.deep_merge_under(cfg, defaults)
 
-if cfg.platforms.solaris then
-   defaults.arch = "solaris-"..cfg.target_cpu
-   --defaults.platforms = {"unix", "solaris"}
-   defaults.variables.MAKE = "gmake"
+   -- FIXME get rid of this
+   if not cfg.check_certificates then
+      cfg.variables.CURLNOCERTFLAG = "-k"
+      cfg.variables.WGETNOCERTFLAG = "--no-check-certificate"
+   end
 end
 
--- Expose some more values detected by LuaRocks for use by rockspec authors.
-defaults.variables.LIB_EXTENSION = defaults.lib_extension
-defaults.variables.OBJ_EXTENSION = defaults.obj_extension
-defaults.variables.LUAROCKS_PREFIX = site_config.LUAROCKS_PREFIX
-defaults.variables.LUA = site_config.LUA_DIR_SET and (defaults.variables.LUA_BINDIR.."/"..defaults.lua_interpreter) or defaults.lua_interpreter
+--------------------------------------------------------------------------------
 
--- Add built-in modules to rocks_provided
-defaults.rocks_provided["lua"] = cfg.lua_version.."-1"
+local cfg = {}
 
-if bit32 then -- Lua 5.2+
-   defaults.rocks_provided["bit32"] = cfg.lua_version.."-1"
-end
+function cfg.init(lua_data, warning)
+   lua_data = lua_data or {}
 
-if utf8 then -- Lua 5.3+
-   defaults.rocks_provided["utf8"] = cfg.lua_version.."-1"
-end
+   local hc_ok, hardcoded = pcall(require, "luarocks.core.hardcoded")
+   if not hc_ok then
+      hardcoded = {}
+   end
 
-if package.loaded.jit then
-   -- LuaJIT
-   local lj_version = package.loaded.jit.version:match("LuaJIT (.*)"):gsub("%-","")
-   defaults.rocks_provided["luabitop"] = lj_version.."-1"
-   defaults.rocks_provided_3_0["luajit"] = lj_version.."-1"
-end
+   local lua_version = lua_data.lua_version or hardcoded.LUA_VERSION or _VERSION:sub(5)
+   local luajit_version = lua_data.luajit_version or hardcoded.LUAJIT_VERSION or (jit and jit.version:sub(8))
+   local lua_interpreter = lua_data.lua_interpreter or hardcoded.LUA_INTERPRETER or (arg[-1] and arg[-1]:gsub(".*[\\/]", "")) or (is_windows and "lua.exe" or "lua")
+   local lua_bindir = lua_data.lua_bindir or hardcoded.LUA_BINDIR or (arg[-1] and arg[-1]:gsub("[\\/][^\\/]+$", ""))
+   local lua_incdir = lua_data.lua_incdir or hardcoded.LUA_INCDIR
+   local lua_libdir = lua_data.lua_libdir or hardcoded.LUA_LIBDIR
+   local lua_dir = lua_data.lua_dir or hardcoded.LUA_DIR
+   
+   local init = cfg.init
 
--- Use defaults:
+   ----------------------------------------
+   -- Reset the cfg table.
+   ----------------------------------------
 
--- Populate some arrays with values from their 'defaults' counterparts
--- if they were not already set by user.
-for _, entry in ipairs({"variables", "rocks_provided"}) do
-   if not cfg[entry] then
-      cfg[entry] = {}
-   end
-   for k,v in pairs(defaults[entry]) do
-      if not cfg[entry][k] then
-         cfg[entry][k] = v
-      end
+   for k, _ in pairs(cfg) do
+      cfg[k] = nil
    end
-end
-setmetatable(defaults.rocks_provided_3_0, { __index = cfg.rocks_provided })
-
--- For values not set in the config file, use values from the 'defaults' table.
-local cfg_mt = {
-   __index = function(t, k)
-      local default = defaults[k]
-      if default then
-         rawset(t, k, default)
-      end
-      return default
-   end
-}
-setmetatable(cfg, cfg_mt)
 
-if not cfg.check_certificates then
-   cfg.variables.CURLNOCERTFLAG = "-k"
-   cfg.variables.WGETNOCERTFLAG = "--no-check-certificate"
-end
+   cfg.program_version = program_version
+   cfg.program_series = program_series
+   cfg.major_version = major_version
 
-function cfg.make_paths_from_tree(tree)
-   local lua_path, lib_path, bin_path
-   if type(tree) == "string" then
-      lua_path = tree..cfg.lua_modules_path
-      lib_path = tree..cfg.lib_modules_path
-      bin_path = tree.."/bin"
+   cfg.lua_version = lua_version
+   cfg.luajit_version = luajit_version
+   cfg.lua_interpreter = lua_interpreter
+
+   cfg.variables = {
+      LUA_DIR = lua_dir,
+      LUA_BINDIR = lua_bindir,
+      LUA_INCDIR = lua_incdir,
+      LUA_LIBDIR = lua_libdir,
+   }
+
+   cfg.rocks_trees = {}
+
+   cfg.init = init
+
+   ----------------------------------------
+   -- System detection.
+   ----------------------------------------
+
+   -- A proper build of LuaRocks will hardcode the system
+   -- and proc values with hardcoded.SYSTEM and hardcoded.PROCESSOR.
+   -- If that is not available, we try to identify the system.
+   local system = hardcoded.SYSTEM
+   local processor = hardcoded.PROCESSOR
+   if is_windows then
+      system = system or "Windows"
+      if not processor then
+         local pe_parser = require("luarocks.fs.win32.pe-parser")
+         local err
+         local lua_exe = lua_bindir .. "\\" .. lua_interpreter
+         processor, err = pe_parser.get_architecture(lua_exe)
+         if err then
+            processor = "x86"
+         end
+      end
    else
-      lua_path = tree.lua_dir or tree.root..cfg.lua_modules_path
-      lib_path = tree.lib_dir or tree.root..cfg.lib_modules_path
-      bin_path = tree.bin_dir or tree.root.."/bin"
+      system = system or util.popen_read("uname -s")
+      processor = processor or util.popen_read("uname -m")
    end
-   return lua_path, lib_path, bin_path
-end
 
-function cfg.package_paths(current)
-   local new_path, new_cpath, new_bin = {}, {}, {}
-   local function add_tree_to_paths(tree)
-      local lua_path, lib_path, bin_path = cfg.make_paths_from_tree(tree)
-      table.insert(new_path, lua_path.."/?.lua")
-      table.insert(new_path, lua_path.."/?/init.lua")
-      table.insert(new_cpath, lib_path.."/?."..cfg.lib_extension)
-      table.insert(new_bin, bin_path)
-   end
-   if current then
-      add_tree_to_paths(current)
+   cfg.target_cpu = processor
+
+   local platforms = make_platforms(system)
+
+   ----------------------------------------
+   -- Platform is determined.
+   -- Let's load the config files.
+   ----------------------------------------
+
+   local sys_config_file
+   local home_config_file
+   do
+      local sysconfdir = os.getenv("LUAROCKS_SYSCONFDIR") or hardcoded.SYSCONFDIR
+      local sdir, hdir
+      if platforms.windows then
+         cfg.home = os.getenv("APPDATA") or "c:"
+         sdir = sysconfdir or (os.getenv("PROGRAMFILES") or "c:") .. "/luarocks"
+         hdir = cfg.home.."/luarocks"
+         cfg.home_tree = cfg.home.."/luarocks"
+      else
+         cfg.home = os.getenv("HOME") or ""
+         sdir = sysconfdir or "/etc/luarocks"
+         hdir = cfg.home.."/.luarocks"
+         cfg.home_tree = (os.getenv("USER") ~= "root") and cfg.home.."/.luarocks/"
+      end
+      sys_config_file = sdir .. "/config-"..cfg.lua_version..".lua"
+      home_config_file = hdir .. "/config-"..cfg.lua_version..".lua"
+
+      sys_config_file = sys_config_file:gsub("\\", "/")
+      home_config_file = home_config_file:gsub("\\", "/")
    end
-   for _,tree in ipairs(cfg.rocks_trees) do
-      add_tree_to_paths(tree)
+
+   -- Load system configuration file
+   local sys_config_ok, err = load_config_file(cfg, platforms, sys_config_file)
+   if err then
+      return nil, err, "config"
    end
-   if extra_luarocks_module_dir then
-      table.insert(new_path, extra_luarocks_module_dir)
+
+   -- Load user configuration file (if allowed)
+   local home_config_ok
+   if not hardcoded.FORCE_CONFIG then
+      local env_var   = "LUAROCKS_CONFIG_" .. lua_version:gsub("%.", "_")
+      local env_value = os.getenv(env_var)
+      if not env_value then
+         env_var   = "LUAROCKS_CONFIG"
+         env_value = os.getenv(env_var)
+      end
+      -- first try environment provided file, so we can explicitly warn when it is missing
+      if env_value then
+         local env_ok, err = load_config_file(cfg, platforms, env_value)
+         if err then
+            return nil, err, "config"
+         elseif warning and not env_ok then
+            warning("Warning: could not load configuration file `"..env_value.."` given in environment variable "..env_var.."\n")
+         end
+         if env_ok then
+            home_config_ok = true
+            home_config_file = env_value
+         end
+      end
+
+      -- try the alternative defaults if there was no environment specified file or it didn't work
+      if not home_config_ok then
+         home_config_ok = load_config_file(cfg, platforms, home_config_file)
+         if err then
+            return nil, err, "config"
+         end
+      end
    end
-   return table.concat(new_path, ";"), table.concat(new_cpath, ";"), table.concat(new_bin, cfg.export_path_separator)
-end
 
-function cfg.init_package_paths()
-   local lr_path, lr_cpath, lr_bin = cfg.package_paths()
-   package.path = util.cleanup_path(package.path .. ";" .. lr_path, ";", cfg.lua_version)
-   package.cpath = util.cleanup_path(package.cpath .. ";" .. lr_cpath, ";", cfg.lua_version)
-end
+   ----------------------------------------
+   -- Config files are loaded.
+   -- Let's finish up the cfg table.
+   ----------------------------------------
+
+   -- Settings given via lua_data (i.e. --lua-dir) take precedence over config files:
+   cfg.lua_version = lua_data.lua_version or cfg.lua_version
+   cfg.luajit_version = lua_data.luajit_version or cfg.luajit_version
+   cfg.lua_interpreter = lua_data.lua_interpreter or cfg.lua_interpreter
+   cfg.variables.LUA_BINDIR = lua_data.lua_bindir or cfg.variables.LUA_BINDIR
+   cfg.variables.LUA_INCDIR = lua_data.lua_incdir or cfg.variables.LUA_INCDIR
+   cfg.variables.LUA_LIBDIR = lua_data.lua_libdir or cfg.variables.LUA_LIBDIR
+
+   -- Build a default list of rocks trees if not given
+   if not next(cfg.rocks_trees) then
+      if cfg.home_tree then
+         table.insert(cfg.rocks_trees, { name = "user", root = cfg.home_tree } )
+      end
+      if hardcoded.PREFIX then
+         table.insert(cfg.rocks_trees, { name = "system", root = hardcoded.PREFIX } )
+      end
+   end
 
-function cfg.which_config()
-   local ret = {
-      system = {
-         file = sys_config_file or sys_config_file_default,
-         ok = sys_config_ok,
-      },
-      user = {
-         file = home_config_file or home_config_file_default,
-         ok = home_config_ok,
+   local defaults = make_defaults(lua_version, processor, platforms, cfg.home)
+   defaults.rocks_provided, defaults.rocks_provided_3_0 = make_rocks_provided(lua_version, luajit_version)
+   use_defaults(cfg, defaults)
+
+   cfg.variables.LUA = cfg.variables.LUA or cfg.variables.LUA_BINDIR .. "/" .. cfg.lua_interpreter
+   cfg.user_agent = "LuaRocks/"..cfg.program_version.." "..cfg.arch
+
+   ----------------------------------------
+   -- Attributes of cfg are set.
+   -- Let's add some methods.
+   ----------------------------------------
+
+   function cfg.which_config()
+      return {
+         system = {
+            file = sys_config_file,
+            ok = sys_config_ok,
+         },
+         user = {
+            file = home_config_file,
+            ok = home_config_ok,
+         },
+         nearest = home_config_ok and home_config_file or sys_config_file,
       }
-   }
-   ret.nearest = (ret.user.ok and ret.user.file) or ret.system.file
-   return ret
-end
+   end
+
+   do
+      local function make_paths_from_tree(tree)
+         local lua_path, lib_path, bin_path
+         if type(tree) == "string" then
+            lua_path = tree..cfg.lua_modules_path
+            lib_path = tree..cfg.lib_modules_path
+            bin_path = tree.."/bin"
+         else
+            lua_path = tree.lua_dir or tree.root..cfg.lua_modules_path
+            lib_path = tree.lib_dir or tree.root..cfg.lib_modules_path
+            bin_path = tree.bin_dir or tree.root.."/bin"
+         end
+         return lua_path, lib_path, bin_path
+      end
 
-cfg.user_agent = "LuaRocks/"..cfg.program_version.." "..cfg.arch
+      function cfg.package_paths(current)
+         local new_path, new_cpath, new_bin = {}, {}, {}
+         local function add_tree_to_paths(tree)
+            local lua_path, lib_path, bin_path = make_paths_from_tree(tree)
+            table.insert(new_path, lua_path.."/?.lua")
+            table.insert(new_path, lua_path.."/?/init.lua")
+            table.insert(new_cpath, lib_path.."/?."..cfg.lib_extension)
+            table.insert(new_bin, bin_path)
+         end
+         if current then
+            add_tree_to_paths(current)
+         end
+         for _,tree in ipairs(cfg.rocks_trees) do
+            add_tree_to_paths(tree)
+         end
+         return table.concat(new_path, ";"), table.concat(new_cpath, ";"), table.concat(new_bin, cfg.export_path_separator)
+      end
+   end
 
-cfg.http_proxy = os.getenv("http_proxy")
-cfg.https_proxy = os.getenv("https_proxy")
-cfg.no_proxy = os.getenv("no_proxy")
+   function cfg.init_package_paths()
+      local lr_path, lr_cpath, lr_bin = cfg.package_paths()
+      package.path = util.cleanup_path(package.path .. ";" .. lr_path, ";", lua_version)
+      package.cpath = util.cleanup_path(package.cpath .. ";" .. lr_cpath, ";", lua_version)
+   end
 
---- Check if platform was detected
--- @param query string: The platform name to check.
--- @return boolean: true if LuaRocks is currently running on queried platform.
-function cfg.is_platform(query)
-   assert(type(query) == "string")
+   --- Check if platform was detected
+   -- @param name string: The platform name to check.
+   -- @return boolean: true if LuaRocks is currently running on queried platform.
+   function cfg.is_platform(name)
+      assert(type(name) == "string")
+      return platforms[name]
+   end
 
-   for _, platform in ipairs(cfg.platforms) do
-      if platform == query then
-         return true
+   function cfg.each_platform()
+      local i = 0
+      return function()
+         local p
+         repeat
+            i = i + 1
+            p = platform_order[i]
+         until (not p) or platforms[p]
+         return p
       end
    end
-end
 
-function cfg.each_platform()
-   local i = 0
-   return function()
-      i = i + 1
-      return cfg.platforms[i]
+   function cfg.print_platforms()
+      return table.concat(platforms, ", ")
    end
+
+   return true
 end
 
 return cfg
diff --git a/src/luarocks/deps.lua b/src/luarocks/deps.lua
index bcd6ccf5..3217a18f 100644
--- a/src/luarocks/deps.lua
+++ b/src/luarocks/deps.lua
@@ -187,30 +187,24 @@ end
 -- nil and an error message if any test failed, followed by an optional
 -- error code.
 function deps.fulfill_dependencies(rockspec, depskey, deps_mode)
-   if rockspec.supported_platforms then
-      if not deps.platforms_set then
-         deps.platforms_set = values_set(cfg.platforms)
-      end
-      local supported = nil
+   if rockspec.supported_platforms and next(rockspec.supported_platforms) then
+      local supported = false
       for _, plat in pairs(rockspec.supported_platforms) do
          local neg
          neg, plat = plat:match("^(!?)(.*)")
          if neg == "!" then
-            if deps.platforms_set[plat] then
+            if cfg.is_platform(plat) then
                return nil, "This rockspec for "..rockspec.package.." does not support "..plat.." platforms."
             end
          else
-            if deps.platforms_set[plat] then
+            if cfg.is_platform(plat) then
                supported = true
-            else
-               if supported == nil then
-                  supported = false
-               end
+               break
             end
          end
       end
       if supported == false then
-         local plats = table.concat(cfg.platforms, ", ")
+         local plats = cfg.print_platforms()
          return nil, "This rockspec for "..rockspec.package.." does not support "..plats.." platforms."
       end
    end
diff --git a/src/luarocks/fs/lua.lua b/src/luarocks/fs/lua.lua
index b53ef8cc..88fc31d9 100644
--- a/src/luarocks/fs/lua.lua
+++ b/src/luarocks/fs/lua.lua
@@ -557,7 +557,7 @@ local redirect_protocols = {
 local function request(url, method, http, loop_control)
    local result = {}
 
-   local proxy = cfg.http_proxy
+   local proxy = os.getenv("http_proxy")
    if type(proxy) ~= "string" then proxy = nil end
    -- LuaSocket's http.request crashes when given URLs missing the scheme part.
    if proxy and not proxy:find("://") then
@@ -691,7 +691,7 @@ function fs_lua.download(url, filename, cache)
    filename = fs.absolute_name(filename or dir.base_name(url))
 
    -- delegate to the configured downloader so we don't have to deal with whitelists
-   if cfg.no_proxy then
+   if os.getenv("no_proxy") then
       return fs.use_downloader(url, filename, cache)
    end
 
@@ -702,7 +702,7 @@ function fs_lua.download(url, filename, cache)
       ok, err = ftp_request(url, filename)
    elseif util.starts_with(url, "https:") then
       -- skip LuaSec when proxy is enabled since it is not supported
-      if luasec_ok and not cfg.https_proxy then
+      if luasec_ok and not os.getenv("https_proxy") then
          ok, err = http_request(url, filename, https, cache)
       else
          https_err = true
@@ -919,7 +919,7 @@ function fs_lua.is_lua(filename)
   filename = filename:gsub([[%\]],"/")   -- normalize on fw slash to prevent escaping issues
   local lua = fs.Q(dir.path(cfg.variables["LUA_BINDIR"], cfg.lua_interpreter))  -- get lua interpreter configured
   -- execute on configured interpreter, might not be the same as the interpreter LR is run on
-  local result = fs.execute_string(lua..[[ -e "if loadfile(']]..filename..[[') then os.exit() else os.exit(1) end"]])
+  local result = fs.execute_string(lua..[[ -e "if loadfile(']]..filename..[[') then os.exit(0) else os.exit(1) end"]])
   return (result == true)
 end
 
diff --git a/src/luarocks/loader.lua b/src/luarocks/loader.lua
index 078e4068..537adf94 100644
--- a/src/luarocks/loader.lua
+++ b/src/luarocks/loader.lua
@@ -16,7 +16,10 @@ local is_clean = not package.loaded["luarocks.core.cfg"]
 
 -- This loader module depends only on core modules.
 local cfg = require("luarocks.core.cfg")
-cfg.init_package_paths()
+local cfg_ok, err = cfg.init()
+if cfg_ok then
+   cfg.init_package_paths()
+end
 
 local path = require("luarocks.core.path")
 local manif = require("luarocks.core.manif")
diff --git a/src/luarocks/util.lua b/src/luarocks/util.lua
index 5a111dbb..fd2b7b42 100644
--- a/src/luarocks/util.lua
+++ b/src/luarocks/util.lua
@@ -115,6 +115,7 @@ local supported_flags = {
    ["lr-bin"] = true,
    ["lr-cpath"] = true,
    ["lr-path"] = true,
+   ["lua-dir"] = "<path>",
    ["lua-version"] = "<vers>",
    ["lua-ver"] = true,
    ["lua-incdir"] = true,