2009-05-18 Colin D Bennett <colin@gibibit.com>

	Display error messages when parsing a Lua statement fails.  Previously,
	executing a syntactically invalid statement like ")foo" or "bar;" would
	silently fail.

	* script/lua/grub_main.c (handle_lua_error): New function.
	(grub_lua_parse_line): Improved reporting of Lua parser and execution
	errors.

diff --git a/ChangeLog b/ChangeLog
index c26b09ced78374f2af19055523464f4ca6ef088d..abd465164332a48c931e2e6e565e6974dfe12019 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2009-05-18  Colin D Bennett  <colin@gibibit.com>
+
+       Display error messages when parsing a Lua statement fails.  Previously,
+       executing a syntactically invalid statement like ")foo" or "bar;" would
+       silently fail.
+
+       * script/lua/grub_main.c (handle_lua_error): New function.
+       (grub_lua_parse_line): Improved reporting of Lua parser and execution
+       errors.
+
 2009-05-17  Vladimir Serbinenko  <phcoder@gmail.com>
 
        Remove -Werror which causes build to fail on some systems

diff --git a/script/lua/grub_main.c b/script/lua/grub_main.c
index 2de59205c5276b2d3d9ef625c2412e4a90acd8a1..03f890a9a4b9aee69116672a34c63f15436b975a 100644 (file)
--- a/script/lua/grub_main.c
+++ b/script/lua/grub_main.c
@@ -26,6 +26,21 @@
 
 static lua_State *state;
 
+/* Call `grub_error' to report a Lua error.  The error message string must be
+   on the top of the Lua stack (at index -1).  The error message is popped off
+   the Lua stack before this function returns.  */
+static void
+handle_lua_error (const char *error_type)
+{
+  const char *error_msg;
+  error_msg = lua_tostring (state, -1);
+  if (error_msg == NULL)
+    error_msg = "(error message not a string)";
+  grub_error (GRUB_ERR_BAD_ARGUMENT, "%s: %s", error_type, error_msg);
+  /* Pop the error message.  */
+  lua_pop (state, 1);
+}
+
 static grub_err_t
 grub_lua_parse_line (char *line, grub_reader_getline_t getline)
 {
@@ -35,37 +50,47 @@ grub_lua_parse_line (char *line, grub_reader_getline_t getline)
   lua_settop(state, 0);
   while (1)
     {
-      r = luaL_loadbuffer (state, line, grub_strlen (line), "grub");
+      r = luaL_loadbuffer (state, line, grub_strlen (line), "=grub");
       if (! r)
        {
+         /* No error: Execute the statement.  */
          r = lua_pcall (state, 0, 0, 0);
          if (r)
-           grub_error (GRUB_ERR_BAD_ARGUMENT, "lua command fails");
+           {
+             handle_lua_error ("Lua");
+             break;
+           }
          else
            {
              grub_free (old_line);
              return grub_errno;
            }
-         break;
        }
 
       if (r == LUA_ERRSYNTAX)
        {
+         /* Check whether the syntax error is a result of an incomplete
+            statement.  If it is, then try to complete the statement by
+            reading more lines.  */
          size_t lmsg;
-         const char *msg = lua_tolstring(state, -1, &lmsg);
-         const char *tp = msg + lmsg - (sizeof(LUA_QL("<eof>")) - 1);
-         if (grub_strstr(msg, LUA_QL("<eof>")) == tp)
+         const char *msg = lua_tolstring (state, -1, &lmsg);
+         const char *tp = msg + lmsg - (sizeof (LUA_QL ("<eof>")) - 1);
+         if (grub_strstr (msg, LUA_QL ("<eof>")) == tp)
            {
              char *n, *t;
              int len;
 
-             lua_pop(state, 1);
+             /* Discard the error message.  */
+             lua_pop (state, 1);
+             /* Try to read another line to complete the statement.  */
              if ((getline (&n, 1)) || (! n))
                {
                  grub_error (GRUB_ERR_BAD_ARGUMENT, "incomplete command");
                  break;
                }
 
+             /* More input was available: Add it to the current statement
+                contents.  */
              len = grub_strlen (line);
              t = grub_malloc (len + grub_strlen (n) + 2);
              if (! t)
@@ -76,8 +101,17 @@ grub_lua_parse_line (char *line, grub_reader_getline_t getline)
              grub_strcpy (t + len + 1, n);
              grub_free (old_line);
              line = old_line = t;
+             /* Try again to execute the statement now that more input has
+                been appended.  */
              continue;
            }
+         /* The syntax error was not the result of an incomplete line.  */
+         handle_lua_error ("Lua syntax error");
+       }
+      else
+       {
+         /* Handle errors other than syntax errors (out of memory, etc.).  */
+         handle_lua_error ("Lua parser failed");
        }
 
       break;
@@ -102,10 +136,10 @@ GRUB_MOD_INIT(lua)
   state = lua_open ();
   if (state)
     {
-      lua_gc(state, LUA_GCSTOP, 0);
-      luaL_openlibs(state);
-      luaL_register(state, "grub", grub_lua_lib);
-      lua_gc(state, LUA_GCRESTART, 0);
+      lua_gc (state, LUA_GCSTOP, 0);
+      luaL_openlibs (state);
+      luaL_register (state, "grub", grub_lua_lib);
+      lua_gc (state, LUA_GCRESTART, 0);
       grub_parser_register ("lua", &grub_lua_parser);
     }
 }
@@ -115,6 +149,6 @@ GRUB_MOD_FINI(lua)
   if (state)
     {
       grub_parser_unregister (&grub_lua_parser);
-      lua_close(state);
+      lua_close (state);
     }
 }