Re: [PATCH] Adds null check for DisplayStatus (wasRe: [Qemu-devel] [6344] graphical_console_init change (Stefano Stabellini)

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Anthony Liguori wrote:

> Stefano Stabellini wrote:
>> Thanks for testing it.
>> Anthony, before committing this patch, check out the other equivalent
>> patch I sent as I reply to 'add a -vga none cli option'.
>>   
> 
> Hi Stefan,
> 
> Are you working on a fix for the SEGV when not using -nographic?  If I run:
> 
> qemu -hda image.foo -snapshot -vga none
> 
> I get a segv b/c SDL_SetVideoMode() uses ds_get_width/height and
> ds->surface == NULL.
> 



Yes, the complete fix is the following, it also solves the other bug that
arises when you set -vga none but you do not specify -nographic:


diff --git a/vl.c b/vl.c
index bfacdcf..b356323 100644
--- a/vl.c
+++ b/vl.c
@@ -2774,26 +2774,17 @@ DisplayState *get_displaystate(void)
 }
 
 /* dumb display */
-
-static void dumb_update(DisplayState *ds, int x, int y, int w, int h)
+static void dumb_display_init(void)
 {
-}
-
-static void dumb_resize(DisplayState *ds)
-{
-}
+    DisplayState *ds;
 
-static void dumb_display_init(DisplayState *ds)
-{
-    DisplayChangeListener *dcl = qemu_mallocz(sizeof(DisplayChangeListener));
-    if (!dcl)
+    ds = (DisplayState *) qemu_mallocz(sizeof(DisplayState));
+    if (ds == NULL) {
+        fprintf(stderr, "dumb_display_init: DisplayState allocation failed\n");
         exit(1);
-    dcl->dpy_update = dumb_update;
-    dcl->dpy_resize = dumb_resize;
-    dcl->dpy_refresh = NULL;
-    dcl->idle = 1;
-    dcl->gui_timer_interval = 500;
-    register_displaychangelistener(ds, dcl);
+    }
+    ds->surface = qemu_create_displaysurface(640, 480, 32, 640 * 4);
+    register_displaystate(ds);
 }
 
 /***********************************************************/
@@ -5535,6 +5526,8 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    if (!display_state)
+        dumb_display_init();
     /* just use the first displaystate for the moment */
     ds = display_state;
     /* terminal init */
@@ -5543,8 +5536,6 @@ int main(int argc, char **argv, char **envp)
             fprintf(stderr, "fatal: -nographic can't be used with -curses\n");
             exit(1);
         }
-        /* nearly nothing to do */
-        dumb_display_init(ds);
     } else { 
 #if defined(CONFIG_CURSES)
             if (curses) {
@@ -5563,8 +5554,6 @@ int main(int argc, char **argv, char **envp)
                     sdl_display_init(ds, full_screen, no_frame);
 #elif defined(CONFIG_COCOA)
                     cocoa_display_init(ds, full_screen);
-#else
-                    dumb_display_init(ds);
 #endif
             }
     }