console: modify ppm_save to take a pixman image ref

The function is going to be called from a coroutine, and may yield.
Let's ensure our image reference doesn't change over time (due to resize
etc) by keeping a ref.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20201027133602.3038018-3-marcandre.lureau@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/console.c

@@ -195,7 +195,6 @@ static void dpy_refresh(DisplayState *s);
 static DisplayState *get_alloc_displaystate(void);
 static void text_console_update_cursor_timer(void);
 static void text_console_update_cursor(void *opaque);
-static bool ppm_save(int fd, DisplaySurface *ds, Error **errp);
 
 static void gui_update(void *opaque)
 {
@@ -311,16 +310,16 @@ void graphic_hw_invalidate(QemuConsole *con)
     }
 }
 
-static bool ppm_save(int fd, DisplaySurface *ds, Error **errp)
+static bool ppm_save(int fd, pixman_image_t *image, Error **errp)
 {
-    int width = pixman_image_get_width(ds->image);
-    int height = pixman_image_get_height(ds->image);
+    int width = pixman_image_get_width(image);
+    int height = pixman_image_get_height(image);
     g_autoptr(Object) ioc = OBJECT(qio_channel_file_new_fd(fd));
     g_autofree char *header = NULL;
     g_autoptr(pixman_image_t) linebuf = NULL;
     int y;
 
-    trace_ppm_save(fd, ds);
+    trace_ppm_save(fd, image);
 
     header = g_strdup_printf("P6\n%d %d\n%d\n", width, height, 255);
     if (qio_channel_write_all(QIO_CHANNEL(ioc),
@@ -330,7 +329,7 @@ static bool ppm_save(int fd, DisplaySurface *ds, Error **errp)
 
     linebuf = qemu_pixman_linebuf_create(PIXMAN_BE_r8g8b8, width);
     for (y = 0; y < height; y++) {
-        qemu_pixman_linebuf_fill(linebuf, ds->image, width, 0, y);
+        qemu_pixman_linebuf_fill(linebuf, image, width, 0, y);
         if (qio_channel_write_all(QIO_CHANNEL(ioc),
                                   (char *)pixman_image_get_data(linebuf),
                                   pixman_image_get_stride(linebuf), errp) < 0) {
@@ -344,6 +343,7 @@ static bool ppm_save(int fd, DisplaySurface *ds, Error **errp)
 void qmp_screendump(const char *filename, bool has_device, const char *device,
                     bool has_head, int64_t head, Error **errp)
 {
+    g_autoptr(pixman_image_t) image = NULL;
     QemuConsole *con;
     DisplaySurface *surface;
     int fd;
@@ -372,6 +372,7 @@ void qmp_screendump(const char *filename, bool has_device, const char *device,
         error_setg(errp, "no surface");
         return;
     }
+    image = pixman_image_ref(surface->image);
 
     fd = qemu_open_old(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0666);
     if (fd == -1) {
@@ -380,7 +381,7 @@ void qmp_screendump(const char *filename, bool has_device, const char *device,
         return;
     }
 
-    if (!ppm_save(fd, surface, errp)) {
+    if (!ppm_save(fd, image, errp)) {
         qemu_unlink(filename);
     }
 }

ui/trace-events

@@ -15,7 +15,7 @@ displaysurface_create_pixman(void *display_surface) "surface=%p"
 displaysurface_free(void *display_surface) "surface=%p"
 displaychangelistener_register(void *dcl, const char *name) "%p [ %s ]"
 displaychangelistener_unregister(void *dcl, const char *name) "%p [ %s ]"
-ppm_save(int fd, void *display_surface) "fd=%d surface=%p"
+ppm_save(int fd, void *image) "fd=%d image=%p"
 
 # gtk-egl.c
 # gtk-gl-area.c