Signal config errors via a naughty popup

If loading of any config file fails, awesome will now remember the error message
and make it available to lua. The default config is modified to open a naughty
popup on errors.

This should help all those people who modify their config and then wonder why
there change is ignored, not noticing awesome's error message on stderr.

Signed-off-by: Uli Schlachter <psychon@znc.in>

awesome.c

@@ -339,6 +339,7 @@ main(int argc, char **argv)
     p_clear(&globalconf, 1);
     globalconf.keygrabber = LUA_REFNIL;
     globalconf.mousegrabber = LUA_REFNIL;
+    buffer_init(&globalconf.startup_errors);
 
     /* save argv */
     for(i = 0; i < argc; i++)

awesomerc.lua.in

@@ -9,6 +9,16 @@ require("beautiful")
 -- Notification library
 require("naughty")
 
+-- {{{ Error handling
+-- Check if awesome encountered an error during startup and fell back to
+-- another config (This code will only ever execute for the fallback config)
+if awesome.startup_errors then
+    naughty.notify({ preset = naughty.config.presets.critical,
+                     title = "Oops, there were errors during startup!",
+                     text = awesome.startup_errors })
+end
+-- }}}
+
 -- {{{ Variable definitions
 -- Themes define colours, icons, and wallpapers
 beautiful.init("@AWESOME_THEMES_PATH@/default/theme.lua")

globalconf.h

@@ -33,6 +33,7 @@
 #include "objects/key.h"
 #include "color.h"
 #include "common/xembed.h"
+#include "common/buffer.h"
 
 #define ROOT_WINDOW_EVENT_MASK \
     (const uint32_t []) { \
@@ -87,6 +88,8 @@ typedef struct
     client_array_t stack;
     /** Lua VM state */
     lua_State *L;
+    /** All errors messages from loading config files */
+    buffer_t startup_errors;
     /** The event loop */
     struct ev_loop *loop;
     /** The key grabber function */

luaa.c

@@ -396,6 +396,13 @@ luaA_awesome_index(lua_State *L)
         lua_pushliteral(L, AWESOME_VERSION);
     else if(a_strcmp(buf, "release") == 0)
         lua_pushliteral(L, AWESOME_RELEASE);
+    else if(a_strcmp(buf, "startup_errors") == 0)
+    {
+        if (globalconf.startup_errors.len == 0)
+            return 0;
+        lua_pushstring(L, globalconf.startup_errors.s);
+        return 1;
+    }
     else
         return 0;
 
@@ -632,6 +639,14 @@ luaA_init(xdgHandle* xdg)
     signal_add(&global_signals, "exit");
 }
 
+static void
+luaA_startup_error(const char *err)
+{
+    if (globalconf.startup_errors.len > 0)
+        buffer_addsl(&globalconf.startup_errors, "\n\n");
+    buffer_adds(&globalconf.startup_errors, err);
+}
+
 static bool
 luaA_loadrc(const char *confpath, bool run)
 {
@@ -644,7 +659,9 @@ luaA_loadrc(const char *confpath, bool run)
             conffile = a_strdup(confpath);
             if(lua_pcall(globalconf.L, 0, LUA_MULTRET, 0))
             {
-                fprintf(stderr, "%s\n", lua_tostring(globalconf.L, -1));
+                const char *err = lua_tostring(globalconf.L, -1);
+                luaA_startup_error(err);
+                fprintf(stderr, "%s\n", err);
                 /* An error happened, so reset this. */
                 conffile = NULL;
             }
@@ -658,7 +675,11 @@ luaA_loadrc(const char *confpath, bool run)
         }
     }
     else
-        fprintf(stderr, "%s\n", lua_tostring(globalconf.L, -1));
+    {
+        const char *err = lua_tostring(globalconf.L, -1);
+        luaA_startup_error(err);
+        fprintf(stderr, "%s\n", err);
+    }
 
     return false;
 }