add more comments on changes to the lua library

add basic test for the new os.outputof behavior

src/host/lua-5.1.4/src/liolib.c

@@ -105,15 +105,26 @@ static int io_noclose (lua_State *L) {
 /*
 ** function to close 'popen' files
 */
+/*
+ * PREAAKE change: return both output and exit code
+ */
 static int io_pclose (lua_State *L) {
   FILE **p = tofilep(L);
   int result = lua_pclose(L, *p);
   *p = NULL;
   if (result == -1) {
+	  /*
+	   * pclose call failure
+	   */
 	  return pushresult(L, 0, NULL);
   }
   lua_pushboolean(L, 1);
-  lua_pushinteger(L, result / 255);
+  /**
+   * On success, pcluse returns a 2 byte length integer
+   * where the higher byte contains the command exit code
+   */
+  result /= 255;
+  lua_pushinteger(L, result);
   return 2;
 }
 

src/host/lua-5.1.4/src/luaconf.h

@@ -668,11 +668,17 @@ union luai_Cast { double l_d; long l_l; };
 #if defined(LUA_USE_POPEN)
 
 #define lua_popen(L,c,m)	((void)L, fflush(NULL), popen(c,m))
+/*
+ * PREMAKE change: get pclose return value
+ */
 #define lua_pclose(L,file)	((void)L, (pclose(file)))
 
 #elif defined(LUA_WIN)
 
 #define lua_popen(L,c,m)	((void)L, _popen(c,m))
+/*
+ * PREMAKE change: get pclose return value
+ */
 #define lua_pclose(L,file)	((void)L, (_pclose(file)))
 
 #else

tests/base/test_os.lua

@@ -103,3 +103,25 @@
 	function suite.pathsearch_NilPathsAllowed()
 		test.isequal(os.getcwd(), os.pathsearch("premake5.lua", nil, os.getcwd(), nil))
 	end
+
+--
+-- os.pathsearch() tests
+--
+	function suite.outputof_commandExitCode()
+		if os.is("macosx")
+			or os.is("linux")
+			or os.is("solaris")
+			or os.is("bsd")
+		then
+			-- Assumes 'true' and 'false' commands exits
+			-- which should be the case on all *nix platforms 
+			for cmd, exitcode in pairs ({
+				["true"] = 0,
+				["false"] = 1
+			})
+			do
+				local o, e = os.outputof(cmd)
+				test.isequal(e, exitcode)
+			end
+		end
+	end