7 files changed, 238 insertions, 88 deletions

diff --git a/install.bat b/install.bat
index a4257be6..43a2b34f 100644
--- a/install.bat
+++ b/install.bat
@@ -6,8 +6,8 @@ local vars = {}
 

 vars.PREFIX = [[C:\LuaRocks]]

 vars.VERSION = "2.1"

-vars.SYSCONFDIR = [[C:\LuaRocks]]

-vars.ROCKS_TREE = [[C:\LuaRocks]]

+vars.SYSCONFDIR = nil

+vars.ROCKS_TREE = nil

 vars.SCRIPTS_DIR = nil

 vars.LUA_INTERPRETER = nil

 vars.LUA_PREFIX = nil

@@ -27,6 +27,7 @@ local FORCE_CONFIG = false
 local INSTALL_LUA = false

 local USE_MINGW = false

 local REGISTRY = false

+local NOADMIN = false

 

 ---

 -- Some helpers

@@ -82,6 +83,25 @@ local function mkdir (dir)
         return exec([[.\bin\bin\mkdir -p "]]..dir..[[" >NUL]])

 end

 

+-- does the current user have admin priviledges ( = elevated)

+local function permission()

+        return exec("net session >nul 2>&1") -- fails if not admin

+end

+

+-- rename file (full path) to backup (name only), appending number if required

+-- returns the new name (name only)

+local function backup(filename, backupname)

+        local path = filename:match("(.+)%\\.-$").."\\"

+        local nname = backupname

+        local i = 0

+        while exists(path..nname) do

+                i = i + 1

+                nname = backupname..tostring(i)

+        end

+        exec([[REN "]]..filename..[[" "]]..nname..[[" > NUL]])

+        return nname

+end

+

 -- interpolate string with values from 'vars' table

 local function S (tmpl)

         return (tmpl:gsub('%$([%a_][%w_]*)', vars))

@@ -136,6 +156,11 @@ Other options:
 /F             Remove installation directory if it already exists.

 /R             Load registry information to register '.rockspec'

                extension with LuaRocks commands (right-click).

+/NOADMIN       The installer requires admin priviledges. If not

+               available it will elevate a new process. Use this

+               switch to prevent elevation, but make sure the

+               destination paths are all accessible for the current

+               user.

 

 ]])

 end

@@ -151,8 +176,6 @@ local function parse_options(args)
                         os.exit(0)

                 elseif name == "/P" then

                         vars.PREFIX = option.value

-                        vars.SYSCONFDIR = option.value

-                        vars.ROCKS_TREE = option.value

                         P_SET = true

                 elseif name == "/CONFIG" then

                         vars.SYSCONFDIR = option.value

@@ -180,6 +203,8 @@ local function parse_options(args)
                         FORCE = true

                 elseif name == "/R" then

                         REGISTRY = true

+                elseif name == "/NOADMIN" then

+                        NOADMIN = true

                 else

                         die("Unrecognized option: " .. name)

                 end

@@ -376,7 +401,7 @@ local function look_for_lua_install ()
                 then

                         if get_runtime() then

                                 print("Runtime check completed, now testing interpreter...")

-                                if exec(S[[$LUA_BINDIR\$LUA_INTERPRETER -v 2>NUL]]) then

+                                if exec(S[["$LUA_BINDIR\$LUA_INTERPRETER" -v 2>NUL]]) then

                                         print("    Ok")

                                         return true

                                 end

@@ -397,7 +422,7 @@ local function look_for_lua_install ()
                                                 print("Headers found, checking runtime to use...")

                                                 if get_runtime() then

                                                         print("Runtime check completed, now testing interpreter...")

-                                                        if exec(S[[$LUA_BINDIR\$LUA_INTERPRETER -v 2>NUL]]) then

+                                                        if exec(S[["$LUA_BINDIR\$LUA_INTERPRETER" -v 2>NUL]]) then

                                                                 print("    Ok")

                                                                 return true

                                                         end

@@ -411,7 +436,11 @@ local function look_for_lua_install ()
         return false

 end

 

----

+

+-- ***********************************************************

+-- Installer script start

+-- ***********************************************************

+

 -- Poor man's command-line parsing

 local config = {}

 local with_arg = { -- options followed by an argument, others are flags

@@ -427,6 +456,7 @@ local with_arg = { -- options followed by an argument, others are flags
 }

 -- reconstruct argument values with spaces and double quotes

 -- this will be damaged by the batch construction at the start of this file

+local oarg = arg  -- retain old table

 if #arg > 0 then

         farg = table.concat(arg, " ") .. " "

         arg = {}

@@ -448,7 +478,10 @@ if #arg > 0 then
                 while farg:sub(1,1) == " " do farg = farg:sub(2,-1) end -- remove prefix spaces

         end

 end

+for k,v in pairs(oarg) do if k < 1 then arg[k] = v end end -- copy 0 and negative indexes

+oarg = nil

 

+-- build config option table with name and value elements

 local i = 1

 while i <= #arg do

         local opt = arg[i]

@@ -470,6 +503,36 @@ print(S"LuaRocks $VERSION.x installer.\n")
 parse_options(config)

 check_flags()

 

+if not permission() then

+        if not NOADMIN then

+                -- must elevate the process with admin priviledges

+        if not exec("PowerShell /? >NUL 2>&1") then

+          -- powershell is not available, so error out

+          die("No administrative priviledges detected and cannot auto-elevate. Please run with admin priviledges or use the /NOADMIN switch")

+        end

+                print("Need admin priviledges, now elevating a new process to continue installing...")

+                local runner = os.getenv("TEMP").."\\".."LuaRocks_Installer.bat"

+                local f = io.open(runner, "w")

+                f:write("@echo off\n")

+                f:write("CHDIR /D "..arg[0]:match("(.+)%\\.-$").."\n")  -- return to current dir, elevation changes current path

+                f:write('"'..arg[-1]..'" "'..table.concat(arg, '" "', 0)..'"\n')

+                f:write("ECHO Press any key to close this window...\n")

+                f:write("PAUSE > NUL\n")

+                f:write('DEL "'..runner..'"')  -- temp batch file deletes itself

+                f:close()

+                -- run the created temp batch file in elevated mode

+                exec("PowerShell -Command (New-Object -com 'Shell.Application').ShellExecute('"..runner.."', '', '', 'runas')\n")

+                print("Now exiting unpriviledged installer")

+        os.exit()  -- exit here, the newly created elevated process will do the installing

+        else

+                print("Attempting to install without admin priviledges...")

+        end

+else

+        print("Admin priviledges available for installing")

+end

+

+vars.SYSCONFDIR = vars.SYSCONFDIR or vars.PREFIX

+vars.ROCKS_TREE = vars.ROCKS_TREE or vars.PREFIX

 vars.FULL_PREFIX = S"$PREFIX\\$VERSION"

 vars.BINDIR = vars.FULL_PREFIX

 vars.LIBDIR = vars.FULL_PREFIX

@@ -599,8 +662,13 @@ else
 end

 

 

+-- ***********************************************************

+-- Configure LuaRocks

+-- ***********************************************************

+

 print()

 print("Configuring LuaRocks...")

+

 -- Create a site-config file

 if exists(S[[$LUADIR\luarocks\site_config.lua]]) then

         exec(S[[RENAME "$LUADIR\luarocks\site_config.lua" site_config.lua.bak]])

@@ -644,50 +712,56 @@ vars.CONFIG_FILE = vars.SYSCONFDIR.."\\config.lua"
 if not exists(vars.SYSCONFDIR) then

         mkdir(vars.SYSCONFDIR)

 end

-if not exists(vars.CONFIG_FILE) then

-        local f = io.open(vars.CONFIG_FILE, "w")

-        f:write([=[

+if exists(vars.CONFIG_FILE) then

+        local nname = backup(vars.CONFIG_FILE, "config.bak")

+        print("***************")

+        print(S"*** WARNING *** LuaRocks config file already exists: '$CONFIG_FILE'. The old file has been renamed to '"..nname.."'")

+        print("***************")

+end

+local f = io.open(vars.CONFIG_FILE, "w")

+f:write([=[

 rocks_servers = {

    [[http://luarocks.org/repositories/rocks]]

 }

 rocks_trees = {

 ]=])

-        if FORCE_CONFIG then

-                f:write("    home..[[/luarocks]],\n")

-        end

-        f:write(S"    [[$ROCKS_TREE]]\n")

-        f:write("}\n")

-        if vars.SCRIPTS_DIR then

-                f:write(S"scripts_dir=[[$SCRIPTS_DIR]]\n")

-        end

-        f:write("variables = {\n")

-        if USE_MINGW and vars.LUA_RUNTIME == "MSVCRT" then

-                f:write("    MSVCRT = 'm',   -- make MinGW use MSVCRT.DLL as runtime\n")

-        else

-                f:write("    MSVCRT = '"..vars.LUA_RUNTIME.."',\n")

-        end

-        f:write(S"    LUALIB = '$LUA_LIBNAME'\n")

-        f:write("}\n")

-        f:close()

-        print(S"Created LuaRocks config file: $CONFIG_FILE")

+if FORCE_CONFIG then

+        f:write("    home..[[/luarocks]],\n")

+end

+f:write(S"    [[$ROCKS_TREE]]\n")

+f:write("}\n")

+if vars.SCRIPTS_DIR then

+        f:write(S"scripts_dir=[[$SCRIPTS_DIR]]\n")

+end

+f:write("variables = {\n")

+if USE_MINGW and vars.LUA_RUNTIME == "MSVCRT" then

+        f:write("    MSVCRT = 'm',   -- make MinGW use MSVCRT.DLL as runtime\n")

 else

-        print(S"LuaRocks config file already exists: $CONFIG_FILE")

+        f:write("    MSVCRT = '"..vars.LUA_RUNTIME.."',\n")

 end

+f:write(S"    LUALIB = '$LUA_LIBNAME'\n")

+f:write("}\n")

+f:write("verbose = false   -- set to 'true' to enable verbose output\n")

+f:close()

+

+print(S"Created LuaRocks config file: $CONFIG_FILE")

+

 

 print()

 print("Creating rocktrees...")

 if not exists(vars.ROCKS_TREE) then

         mkdir(vars.ROCKS_TREE)

-        print(S[[Created rocktree: "$ROCKS_TREE"]])

+        print(S[[Created system rocktree    : "$ROCKS_TREE"]])

 else

-        print(S[[Rocktree exists: "$ROCKS_TREE"]])

+        print(S[[System rocktree exists     : "$ROCKS_TREE"]])

 end

-local APPDATA = os.getenv("APPDATA")

-if not exists(APPDATA.."\\luarocks") then

-        mkdir(APPDATA.."\\luarocks")

-        print([[Created rocktree: "]]..APPDATA..[[\luarocks"]])

+

+vars.LOCAL_TREE = os.getenv("APPDATA")..[[\LuaRocks]]

+if not exists(vars.LOCAL_TREE) then

+        mkdir(vars.LOCAL_TREE)

+        print(S[[Created local user rocktree: "$LOCAL_TREE"]])

 else

-        print([[Rocktree exists: "]]..APPDATA..[[\luarocks"]])

+        print(S[[Local user rocktree exists : "$LOCAL_TREE"]])

 end

 

 -- Load registry information

@@ -712,12 +786,24 @@ exec( S[[del "$FULL_PREFIX\pe-parser.lua" > nul]] )
 -- ***********************************************************

 

 print(S[[

+

 *** LuaRocks is installed! ***

 

- You may want to add the following elements to your paths;

-PATH     :   $LUA_BINDIR;$FULL_PREFIX

-LUA_PATH :   $ROCKS_TREE\share\lua\$LUA_VERSION\?.lua;$ROCKS_TREE\share\lua\$LUA_VERSION\?\init.lua

-LUA_CPATH:   $ROCKS_TREE\lib\lua\$LUA_VERSION\?.dll

+You may want to add the following elements to your paths;

+Lua interpreter;

+  PATH     :   $LUA_BINDIR

+  PATHEXT  :   .LUA

+LuaRocks;

+  PATH     :   $FULL_PREFIX

+  LUA_PATH :   $FULL_PREFIX\lua\?.lua;$FULL_PREFIX\lua\?\init.lua

+Local user rocktree (Note: %APPDATA% is user dependent);

+  PATH     :   %APPDATA%\LuaRocks\bin

+  LUA_PATH :   %APPDATA%\LuaRocks\share\lua\$LUA_VERSION\?.lua;%APPDATA%\LuaRocks\share\lua\$LUA_VERSION\?\init.lua

+  LUA_CPATH:   %APPDATA%\LuaRocks\lib\lua\$LUA_VERSION\?.dll

+System rocktree

+  PATH     :   $ROCKS_TREE\bin

+  LUA_PATH :   $ROCKS_TREE\share\lua\$LUA_VERSION\?.lua;$ROCKS_TREE\share\lua\$LUA_VERSION\?\init.lua

+  LUA_CPATH:   $ROCKS_TREE\lib\lua\$LUA_VERSION\?.dll

 

 ]])

 os.exit(0)

diff --git a/src/luarocks/cfg.lua b/src/luarocks/cfg.lua
index e3d924fb..f66ad1d9 100644
--- a/src/luarocks/cfg.lua
+++ b/src/luarocks/cfg.lua
@@ -322,7 +322,7 @@ if detected.windows then
    local localappdata = os.getenv("LOCALAPPDATA")
    if not localappdata then
       -- for Windows versions below Vista
-      localappdata = os.getenv("USER_PROFILE").."/Local Settings/Application Data"
+      localappdata = os.getenv("USERPROFILE").."/Local Settings/Application Data"
    end
    defaults.local_cache = localappdata.."/LuaRocks/Cache"
 end
diff --git a/src/luarocks/fs.lua b/src/luarocks/fs.lua
index 467b1943..2d799da2 100644
--- a/src/luarocks/fs.lua
+++ b/src/luarocks/fs.lua
@@ -11,6 +11,32 @@ module("luarocks.fs", package.seeall)
 
 local cfg = require("luarocks.cfg")
 
+local pack = table.pack or function(...) return { n = select("#", ...), ... } end
+local unpack = table.unpack or unpack
+
+if cfg.verbose then -- patch io.popen and os.execute to display commands in verbose mode
+  old_popen = io.popen
+  io.popen = function(one, two)
+    if two == nil then
+      print("\nio.popen: ", one)
+    else
+      print("\nio.popen: ", one, "Mode:", two)
+    end
+    return old_popen(one, two)
+  end
+  
+  old_exec = os.execute
+  os.execute = function(cmd)
+    print("\nos.execute: ", cmd)
+    local code = pack(old_exec(cmd))
+    print("Results: "..tostring(code.n))
+    for i = 1,code.n do
+      print("  "..tostring(i).." ("..type(code[i]).."): "..tostring(code[i]))
+    end
+    return unpack(code, 1, code.n)    
+  end
+end
+
 local function load_fns(fs_table)
    for name, fn in pairs(fs_table) do
       if not _M[name] then
diff --git a/src/luarocks/fs/lua.lua b/src/luarocks/fs/lua.lua
index d477d88f..5f7d6c37 100644
--- a/src/luarocks/fs/lua.lua
+++ b/src/luarocks/fs/lua.lua
@@ -106,31 +106,36 @@ end
 
 --- Run the given command, quoting its arguments, silencing its output.
 -- The command is executed in the current directory in the dir stack.
+-- Silencing is omitted if 'verbose' mode is enabled.
 -- @param command string: The command to be executed. No quoting/escaping
 -- is applied.
--- @param ... Strings containing additional arguments, which are quoted.
+-- @param ... Strings containing additional arguments, which will be quoted.
 -- @return boolean: true if command succeeds (status code 0), false
 -- otherwise.
 function execute_quiet(command, ...)
    assert(type(command) == "string")
-   return fs.execute_string(fs.quiet(quote_args(command, ...)))
+   if cfg.verbose then -- omit silencing output
+      return fs.execute_string(quote_args(command, ...))
+   else
+      return fs.execute_string(fs.quiet(quote_args(command, ...)))
+   end
 end
 
 --- Check the MD5 checksum for a file.
 -- @param file string: The file to be checked.
 -- @param md5sum string: The string with the expected MD5 checksum.
--- @return boolean: true if the MD5 checksum for 'file' equals 'md5sum', false if not
+-- @return boolean: true if the MD5 checksum for 'file' equals 'md5sum', false + msg if not
 -- or if it could not perform the check for any reason.
 function check_md5(file, md5sum)
    file = dir.normalize(file)
-   local computed = fs.get_md5(file)
+   local computed, msg = fs.get_md5(file)
    if not computed then
-      return false
+      return false, msg
    end
    if computed:match("^"..md5sum) then
       return true
    else
-      return false
+      return false, "Mismatch MD5 hash for file "..file
    end
 end
 
@@ -146,7 +151,6 @@ if lfs_ok then
 -- @return boolean: true if command succeeds (status code 0), false
 -- otherwise.
 function execute_string(cmd)
-   if cfg.verbose then print("Executing: "..cmd) end
    local code = os.execute(cmd)
    return (code == 0 or code == true)
 end
@@ -644,14 +648,15 @@ if md5_ok then
 
 --- Get the MD5 checksum for a file.
 -- @param file string: The file to be computed.
--- @return string: The MD5 checksum
+-- @return string: The MD5 checksum or nil + error
 function get_md5(file)
    file = fs.absolute_name(file)
    local file = io.open(file, "rb")
-   if not file then return false end
+   if not file then return nil, "Failed to compute MD5 hash for file "..file end
    local computed = md5.sumhexa(file:read("*a"))
    file:close()
-   return computed
+   if computed then return computed end
+   return nil, "Failed to compute MD5 hash for file "..file
 end
 
 end
diff --git a/src/luarocks/fs/unix/tools.lua b/src/luarocks/fs/unix/tools.lua
index e3468ab4..c857b093 100644
--- a/src/luarocks/fs/unix/tools.lua
+++ b/src/luarocks/fs/unix/tools.lua
@@ -328,8 +328,11 @@ function get_md5(file)
    local pipe = io.popen(cmd.." "..fs.absolute_name(file))
    local computed = pipe:read("*a")
    pipe:close()
-   if not computed then return nil end
-   return computed:match("("..("%x"):rep(32)..")")
+   if computed then
+      computed = computed:match("("..("%x"):rep(32)..")")
+   end
+   if computed then return computed end
+   return nil, "Failed to compute MD5 hash for file "..tostring(fs.absolute_name(file))
 end
 
 function get_permissions(filename)
diff --git a/src/luarocks/fs/win32.lua b/src/luarocks/fs/win32.lua
index 0280b3f0..a3f0663b 100644
--- a/src/luarocks/fs/win32.lua
+++ b/src/luarocks/fs/win32.lua
@@ -9,6 +9,15 @@ local cfg = require("luarocks.cfg")
 local dir = require("luarocks.dir")
 local util = require("luarocks.util")
 
+-- Monkey patch io.popen and os.execute to make sure quoting
+-- works as expected.
+-- See http://lua-users.org/lists/lua-l/2013-11/msg00367.html
+local _prefix = "type NUL && "
+local _popen, _execute = io.popen, os.execute
+io.popen = function(cmd, ...) return _popen(_prefix..cmd, ...) end
+os.execute = function(cmd, ...) return _execute(_prefix..cmd, ...) end
+
+
 --- Annotate command string for quiet execution.
 -- @param cmd string: A command-line string.
 -- @return string: The command-line, with silencing annotation.
@@ -173,3 +182,33 @@ function replace_file(old_file, new_file)
    return os.rename(new_file, old_file)
 end
 
+--- Test is file/dir is writable.
+-- Warning: testing if a file/dir is writable does not guarantee
+-- that it will remain writable and therefore it is no replacement
+-- for checking the result of subsequent operations.
+-- @param file string: filename to test
+-- @return boolean: true if file exists, false otherwise.
+function is_writable(file)
+   assert(file)
+   file = dir.normalize(file)
+   local result
+   local tmpname = 'tmpluarockstestwritable.deleteme'
+   if fs.is_dir(file) then
+      local file2 = dir.path(file, tmpname)
+      local fh = io.open(file2, 'wb')
+      result = fh ~= nil
+      if fh then fh:close() end
+      if result then
+         -- the above test might give a false positive when writing to
+         -- c:\program files\ because of VirtualStore redirection on Vista and up
+         -- So check whether it's really there
+         result = fs.exists(file2)
+      end
+      os.remove(file2)
+   else
+      local fh = io.open(file, 'r+b')
+      result = fh ~= nil
+      if fh then fh:close() end
+   end
+   return result
+end
diff --git a/src/luarocks/fs/win32/tools.lua b/src/luarocks/fs/win32/tools.lua
index 979aaff4..0ec46314 100644
--- a/src/luarocks/fs/win32/tools.lua
+++ b/src/luarocks/fs/win32/tools.lua
@@ -12,10 +12,6 @@ local dir_stack = {}
 
 local vars = cfg.variables
 
-local function pack(...)
-   return { n = select("#", ...), ... }
-end
-
 --- Strip the last extension of a filename.
 -- Example: "foo.tar.gz" becomes "foo.tar".
 -- If filename has no dots, returns it unchanged.
@@ -60,16 +56,8 @@ end
 -- otherwise.
 function execute_string(cmd)
    cmd = command_at(fs.current_dir(), cmd)
-   if cfg.verbose then print("Executing: "..tostring(cmd)) end
-   local code = pack(os.execute(cmd))
-   if cfg.verbose then
-      print("Results: "..tostring(code.n))
-      for i = 1,code.n do
-         print("  "..tostring(i).." ("..type(code[i]).."): "..tostring(code[i]))
-      end
-      print()
-   end
-   if code[1] == 0 or code[1] == true then
+   local code = os.execute(cmd)
+   if code == 0 or code == true then
       return true
    else
       return false
@@ -112,7 +100,7 @@ end
 function make_dir(directory)
    assert(directory)
    directory = dir.normalize(directory)
-   fs.execute_quiet(vars.MKDIR.." -p ", directory)
+   fs.execute_quiet(fs.Q(vars.MKDIR).." -p ", directory)
    if not fs.is_dir(directory) then
       return false, "failed making directory "..directory
    end
@@ -125,7 +113,7 @@ end
 -- @param directory string: pathname of directory to remove.
 function remove_dir_if_empty(directory)
    assert(directory)
-   fs.execute_quiet(vars.RMDIR, directory)
+   fs.execute_quiet(fs.Q(vars.RMDIR), directory)
 end
 
 --- Remove a directory if it is empty.
@@ -134,7 +122,7 @@ end
 -- @param directory string: pathname of directory to remove.
 function remove_dir_tree_if_empty(directory)
    assert(directory)
-   fs.execute_quiet(vars.RMDIR, directory)
+   fs.execute_quiet(fs.Q(vars.RMDIR), directory)
 end
 
 --- Copy a file.
@@ -145,7 +133,7 @@ end
 function copy(src, dest)
    assert(src and dest)
    if dest:match("[/\\]$") then dest = dest:sub(1, -2) end
-   local ok = fs.execute(vars.CP, src, dest)
+   local ok = fs.execute(fs.Q(vars.CP), src, dest)
    if ok then
       return true
    else
@@ -160,7 +148,7 @@ end
 -- plus an error message.
 function copy_contents(src, dest)
    assert(src and dest)
-   if fs.execute_quiet(vars.CP.." -dR "..src.."\\*.* "..fs.Q(dest)) then
+   if fs.execute_quiet(fs.Q(vars.CP).." -dR "..src.."\\*.* "..fs.Q(dest)) then
       return true
    else
       return false, "Failed copying "..src.." to "..dest
@@ -191,7 +179,7 @@ function list_dir(at)
       return {}
    end
    local result = {}
-   local pipe = io.popen(command_at(at, vars.LS))
+   local pipe = io.popen(command_at(at, fs.Q(vars.LS)))
    for file in pipe:lines() do
       table.insert(result, file)
    end
@@ -214,7 +202,7 @@ function find(at)
       return {}
    end
    local result = {}
-   local pipe = io.popen(command_at(at, vars.FIND.." 2> NUL"))
+   local pipe = io.popen(command_at(at, fs.Q(vars.FIND).." 2> NUL"))
    for file in pipe:lines() do
       -- Windows find is a bit different
       local first_two = file:sub(1,2)
@@ -233,7 +221,7 @@ end
 -- additional arguments.
 -- @return boolean: true on success, false on failure.
 function zip(zipfile, ...)
-   return fs.execute_quiet(vars.SEVENZ.." -aoa a -tzip", zipfile, ...)
+   return fs.execute_quiet(fs.Q(vars.SEVENZ).." -aoa a -tzip", zipfile, ...)
 end
 
 --- Uncompress files from a .zip archive.
@@ -241,7 +229,7 @@ end
 -- @return boolean: true on success, false on failure.
 function unzip(zipfile)
    assert(zipfile)
-   return fs.execute_quiet(vars.SEVENZ.." -aoa x", zipfile)
+   return fs.execute_quiet(fs.Q(vars.SEVENZ).." -aoa x", zipfile)
 end
 
 --- Test is pathname is a directory.
@@ -257,7 +245,7 @@ end
 -- @return boolean: true if it is a regular file, false otherwise.
 function is_file(file)
    assert(file)
-   return fs.execute(vars.TEST.." -f", file)
+   return fs.execute(fs.Q(vars.TEST).." -f", file)
 end
 
 --- Download a remote file.
@@ -276,7 +264,7 @@ function download(url, filename, cache)
 
    local ok   
    if cfg.downloader == "wget" then
-      local wget_cmd = vars.WGET.." --no-check-certificate --no-cache --user-agent=\""..cfg.user_agent.." via wget\" --quiet "
+      local wget_cmd = fs.Q(vars.WGET).." --no-check-certificate --no-cache --user-agent=\""..cfg.user_agent.." via wget\" --quiet "
       if cache then
          -- --timestamping is incompatible with --output-document,
          -- but that's not a problem for our use cases.
@@ -289,7 +277,7 @@ function download(url, filename, cache)
          ok = fs.execute(wget_cmd..fs.Q(url).." 2> NUL 1> NUL")
       end
    elseif cfg.downloader == "curl" then
-      ok = fs.execute_string(vars.CURL.." -L --user-agent \""..cfg.user_agent.." via curl\" "..fs.Q(url).." 2> NUL 1> "..fs.Q(filename))
+      ok = fs.execute_string(fs.Q(vars.CURL).." -L --user-agent \""..cfg.user_agent.." via curl\" "..fs.Q(url).." 2> NUL 1> "..fs.Q(filename))
    end
    if ok then
       return true, filename
@@ -302,7 +290,7 @@ end
 -- @param archive string: Filename of archive.
 -- @return boolean : success status
 local function gunzip(archive)
-  return fs.execute_quiet(vars.SEVENZ.." -aoa x", archive)
+  return fs.execute_quiet(fs.Q(vars.SEVENZ).." -aoa x", archive)
 end
 
 --- Unpack an archive.
@@ -314,7 +302,7 @@ function unpack_archive(archive)
    assert(type(archive) == "string")
 
    local ok
-   local sevenzx = vars.SEVENZ.." -aoa x"
+   local sevenzx = fs.Q(vars.SEVENZ).." -aoa x"
    if archive:match("%.tar%.gz$") then
       ok = gunzip(archive)
       if ok then
@@ -346,22 +334,25 @@ function unpack_archive(archive)
 end
 
 local md5_cmd = {
-   md5sum = vars.MD5SUM,
-   openssl = vars.OPENSSL.." md5",
-   md5 = vars.MD5,
+   md5sum = fs.Q(vars.MD5SUM),
+   openssl = fs.Q(vars.OPENSSL).." md5",
+   md5 = fs.Q(vars.MD5),
 }
 
 --- Get the MD5 checksum for a file.
 -- @param file string: The file to be computed.
--- @return string: The MD5 checksum
+-- @return string: The MD5 checksum or nil + message
 function get_md5(file)
    local cmd = md5_cmd[cfg.md5checker]
    if not cmd then return nil end
-   local pipe = io.popen(cmd.." "..fs.absolute_name(file))
+   local pipe = io.popen(cmd.." "..fs.Q(fs.absolute_name(file)))
    local computed = pipe:read("*a")
    pipe:close()
-   if not computed then return nil end
-   return computed:match("("..("%x"):rep(32)..")")
+   if computed then
+      computed = computed:match("("..("%x"):rep(32)..")")
+   end
+   if computed then return computed end
+   return nil, "Failed to compute MD5 hash for file "..tostring(fs.absolute_name(file))
 end
 
 --- Test for existance of a file.