Don't pass cairo surfaces around on the lua stack

Now that the C code uses lightuserdata for passing around cairo surfaces, they
are no longer automatically garbage collected. To avoid memleaks, this commit
compares the C code to use cairo_surface_t pointers instead of the lua stack.

This also fixes a memleak were a client's icon was leaked.

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

draw.c

@@ -105,8 +105,8 @@ free_data(void *data)
  * \param data The image's data in ARGB format, will be copied by this function.
  * \return Number of items pushed on the lua stack.
  */
-int
-luaA_surface_from_data(lua_State *L, int width, int height, uint32_t *data)
+cairo_surface_t *
+draw_surface_from_data(int width, int height, uint32_t *data)
 {
     unsigned long int len = width * height;
     unsigned long int i;
@@ -133,10 +133,7 @@ luaA_surface_from_data(lua_State *L, int width, int height, uint32_t *data)
     /* This makes sure that buffer will be freed */
     cairo_surface_set_user_data(surface, &data_key, buffer, &free_data);
 
-    /* lua has to make sure to free the ref or we have a leak */
-    lua_pushlightuserdata(L, surface);
-
-    return 1;
+    return surface;
 }
 
 /** Duplicate the specified image surface.
@@ -205,21 +202,21 @@ image_imlib_load_strerror(Imlib_Load_Error e)
  * \param path file to load
  * \return A cairo image surface or NULL on error.
  */
-int
+cairo_surface_t *
 draw_load_image(lua_State *L, const char *path)
 {
     Imlib_Image imimage;
     Imlib_Load_Error e = IMLIB_LOAD_ERROR_NONE;
-    int ret;
+    cairo_surface_t *ret;
 
     imimage = imlib_load_image_with_error_return(path, &e);
     if (!imimage) {
         luaL_error(L, "Cannot load image '%s': %s", path, image_imlib_load_strerror(e));
-        return 0;
+        return NULL;
     }
 
     imlib_context_set_image(imimage);
-    ret = luaA_surface_from_data(L, imlib_image_get_width(),
+    ret = draw_surface_from_data(imlib_image_get_width(),
             imlib_image_get_height(), imlib_image_get_data_for_reading_only());
     imlib_free_image_and_decache();
     return ret;

draw.h

@@ -65,9 +65,9 @@ a_iso2utf8(const char *str, ssize_t len, char **dest, ssize_t *dlen)
     return false;
 }
 
-int luaA_surface_from_data(lua_State *L, int width, int height, uint32_t *data);
+cairo_surface_t *draw_surface_from_data(int width, int height, uint32_t *data);
 cairo_surface_t *draw_dup_image_surface(cairo_surface_t *surface);
-int draw_load_image(lua_State *L, const char *path);
+cairo_surface_t *draw_load_image(lua_State *L, const char *path);
 
 #endif
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

ewmh.c

@@ -634,7 +634,7 @@ ewmh_window_icon_get_unchecked(xcb_window_t w)
                                     _NET_WM_ICON, XCB_ATOM_CARDINAL, 0, UINT32_MAX);
 }
 
-static int
+static cairo_surface_t *
 ewmh_window_icon_from_reply(xcb_get_property_reply_t *r)
 {
     uint32_t *data;
@@ -655,20 +655,20 @@ ewmh_window_icon_from_reply(xcb_get_property_reply_t *r)
     if (!data[0] || !data[1] || len > r->length - 2)
         return 0;
 
-    return luaA_surface_from_data(globalconf.L, data[0], data[1], data + 2);
+    return draw_surface_from_data(data[0], data[1], data + 2);
 }
 
 /** Get NET_WM_ICON.
  * \param cookie The cookie.
  * \return The number of elements on stack.
  */
-int
+cairo_surface_t *
 ewmh_window_icon_get_reply(xcb_get_property_cookie_t cookie)
 {
     xcb_get_property_reply_t *r = xcb_get_property_reply(globalconf.connection, cookie, NULL);
-    int ret = ewmh_window_icon_from_reply(r);
+    cairo_surface_t *surface = ewmh_window_icon_from_reply(r);
     p_delete(&r);
-    return ret;
+    return surface;
 }
 
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

ewmh.h

@@ -22,6 +22,8 @@
 #ifndef AWESOME_EWMH_H
 #define AWESOME_EWMH_H
 
+#include <cairo.h>
+
 #include "globalconf.h"
 #include "strut.h"
 
@@ -37,7 +39,7 @@ void ewmh_process_client_strut(client_t *);
 void ewmh_update_strut(xcb_window_t, strut_t *);
 void ewmh_update_window_type(xcb_window_t window, uint32_t type);
 xcb_get_property_cookie_t ewmh_window_icon_get_unchecked(xcb_window_t);
-int ewmh_window_icon_get_reply(xcb_get_property_cookie_t);
+cairo_surface_t *ewmh_window_icon_get_reply(xcb_get_property_cookie_t);
 
 #endif
 // vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80

luaa.c

@@ -109,7 +109,12 @@ static int
 luaA_load_image(lua_State *L)
 {
     const char *filename = luaL_checkstring(L, 1);
-    return draw_load_image(L, filename);
+    cairo_surface_t *surface = draw_load_image(L, filename);
+    if (!surface)
+        return 0;
+    /* lua has to make sure to free the ref or we have a leak */
+    lua_pushlightuserdata(L, surface);
+    return 1;
 }
 
 /** UTF-8 aware string length computing.

objects/client.c

@@ -1040,19 +1040,17 @@ luaA_client_isvisible(lua_State *L)
  * \param iidx The image index on the stack.
  */
 void
-client_set_icon(lua_State *L, int cidx, int iidx)
+client_set_icon(client_t *c, cairo_surface_t *s)
 {
-    client_t *c = luaA_checkudata(L, cidx, &client_class);
-    cairo_surface_t *surf = NULL;
-    if(!lua_isnil(L, iidx))
-    {
-        cairo_surface_t **cairo_surface = (cairo_surface_t **)lua_touserdata(L, iidx);
-        surf = draw_dup_image_surface(*cairo_surface);
-    }
+    if (s)
+        s = draw_dup_image_surface(s);
     if(c->icon)
         cairo_surface_destroy(c->icon);
-    c->icon = surf;
-    luaA_object_emit_signal(L, cidx < iidx ? cidx : cidx - 1, "property::icon", 0);
+    c->icon = s;
+
+    luaA_object_push(globalconf.L, c);
+    luaA_object_emit_signal(globalconf.L, -1, "property::icon", 0);
+    lua_pop(globalconf.L, 1);
 }
 
 /** Kill a client.
@@ -1294,7 +1292,10 @@ luaA_client_set_maximized_vertical(lua_State *L, client_t *c)
 static int
 luaA_client_set_icon(lua_State *L, client_t *c)
 {
-    client_set_icon(L, -3, -1);
+    cairo_surface_t *surf = NULL;
+    if(!lua_isnil(L, -1))
+        surf = (cairo_surface_t *)lua_touserdata(L, -1);
+    client_set_icon(c, surf);
     return 0;
 }
 
@@ -1393,7 +1394,7 @@ luaA_client_get_content(lua_State *L, client_t *c)
                                         c->geometry.width,
                                         c->geometry.height,
                                         ~0, XCB_IMAGE_FORMAT_Z_PIXMAP);
-    int retval = 0;
+    cairo_surface_t *surface = NULL;
 
     if(ximage)
     {
@@ -1408,13 +1409,18 @@ luaA_client_get_content(lua_State *L, client_t *c)
                     data[y * ximage->width + x] |= 0xff000000; /* set alpha to 0xff */
                 }
 
-            retval = luaA_surface_from_data(L, ximage->width, ximage->height, data);
+            surface = draw_surface_from_data(ximage->width, ximage->height, data);
             p_delete(&data);
         }
         xcb_image_destroy(ximage);
     }
 
-    return retval;
+    if (!surface)
+        return 0;
+
+    /* lua has to make sure to free the ref or we have a leak */
+    lua_pushlightuserdata(L, surface);
+    return 1;
 }
 
 static int

objects/client.h

@@ -142,7 +142,7 @@ void client_set_transient_for(lua_State *L, int, client_t *);
 void client_set_name(lua_State *L, int, char *);
 void client_set_alt_name(lua_State *L, int, char *);
 void client_set_group_window(lua_State *, int, xcb_window_t);
-void client_set_icon(lua_State *, int, int);
+void client_set_icon(client_t *c, cairo_surface_t *s);
 void client_set_skip_taskbar(lua_State *, int, bool);
 void client_focus(client_t *);
 void client_focus_update(client_t *);

property.c

@@ -241,17 +241,13 @@ property_get_net_wm_icon(client_t *c)
 void
 property_update_net_wm_icon(client_t *c, xcb_get_property_cookie_t cookie)
 {
-    luaA_object_push(globalconf.L, c);
+    cairo_surface_t *surface = ewmh_window_icon_get_reply(cookie);
 
-    if(ewmh_window_icon_get_reply(cookie))
-    {
-        client_set_icon(globalconf.L, -2, -1);
-        /* remove icon */
-        lua_pop(globalconf.L, 1);
-    }
+    if(!surface)
+        return;
 
-    /* remove client */
-    lua_pop(globalconf.L, 1);
+    client_set_icon(c, surface);
+    cairo_surface_destroy(surface);
 }
 
 xcb_get_property_cookie_t