Fix crash saving blend files in background mode

Reading the windows pixels was attempted in background mode.

1 files changed, 52 insertions, 46 deletions

diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index b79a5176d4f..a301b17227d 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -1558,15 +1558,16 @@ static void wm_history_file_update(void)
  * Screen-shot the active window.
  * \{ */
 
-static ImBuf *blend_file_thumb_from_screenshot(bContext *C, BlendThumbnail **thumb_pt)
+static ImBuf *blend_file_thumb_from_screenshot(bContext *C, BlendThumbnail **r_thumb)
 {
-  if (*thumb_pt) {
-    /* We are given a valid thumbnail data, so just generate image from it. */
-    return BKE_main_thumbnail_to_imbuf(NULL, *thumb_pt);
+  *r_thumb = NULL;
+
+  wmWindow *win = CTX_wm_window(C);
+  if (G.background || (win == NULL)) {
+    return NULL;
   }
 
   /* The window to capture should be a main window (without parent). */
-  wmWindow *win = CTX_wm_window(C);
   while (win && win->parent) {
     win = win->parent;
   }
@@ -1595,7 +1596,7 @@ static ImBuf *blend_file_thumb_from_screenshot(bContext *C, BlendThumbnail **thu
 
     BlendThumbnail *thumb = BKE_main_thumbnail_from_imbuf(NULL, thumb_ibuf);
     IMB_freeImBuf(thumb_ibuf);
-    *thumb_pt = thumb;
+    *r_thumb = thumb;
   }
 
   /* Must be freed by caller. */
@@ -1614,8 +1615,15 @@ static ImBuf *blend_file_thumb_from_screenshot(bContext *C, BlendThumbnail **thu
 static ImBuf *blend_file_thumb_from_camera(const bContext *C,
                                            Scene *scene,
                                            bScreen *screen,
-                                           BlendThumbnail **thumb_pt)
+                                           BlendThumbnail **r_thumb)
 {
+  *r_thumb = NULL;
+
+  /* Scene can be NULL if running a script at startup and calling the save operator. */
+  if (G.background || scene == NULL) {
+    return NULL;
+  }
+
   /* will be scaled down, but gives some nice oversampling */
   ImBuf *ibuf;
   BlendThumbnail *thumb;
@@ -1629,17 +1637,6 @@ static ImBuf *blend_file_thumb_from_camera(const bContext *C,
   ARegion *region = NULL;
   View3D *v3d = NULL;
 
-  /* In case we are given a valid thumbnail data, just generate image from it. */
-  if (*thumb_pt) {
-    thumb = *thumb_pt;
-    return BKE_main_thumbnail_to_imbuf(NULL, thumb);
-  }
-
-  /* scene can be NULL if running a script at startup and calling the save operator */
-  if (G.background || scene == NULL) {
-    return NULL;
-  }
-
   if (screen != NULL) {
     area = BKE_screen_find_big_area(screen, SPACE_VIEW3D, 0);
     if (area) {
@@ -1713,13 +1710,13 @@ static ImBuf *blend_file_thumb_from_camera(const bContext *C,
     IMB_scaleImBuf(ibuf, PREVIEW_RENDER_LARGE_HEIGHT, PREVIEW_RENDER_LARGE_HEIGHT);
   }
   else {
-    /* '*thumb_pt' needs to stay NULL to prevent a bad thumbnail from being handled */
+    /* '*r_thumb' needs to stay NULL to prevent a bad thumbnail from being handled. */
     CLOG_WARN(&LOG, "failed to create thumbnail: %s", err_out);
     thumb = NULL;
   }
 
   /* must be freed by caller */
-  *thumb_pt = thumb;
+  *r_thumb = thumb;
 
   return ibuf;
 }
@@ -1752,7 +1749,7 @@ static bool wm_file_write(bContext *C,
   Main *bmain = CTX_data_main(C);
   int len;
   int ok = false;
-  BlendThumbnail *thumb, *main_thumb;
+  BlendThumbnail *thumb = NULL, *main_thumb = NULL;
   ImBuf *ibuf_thumb = NULL;
 
   len = strlen(filepath);
@@ -1802,33 +1799,42 @@ static bool wm_file_write(bContext *C,
   /* don't forget not to return without! */
   WM_cursor_wait(true);
 
-  /* blend file thumbnail */
-  /* Save before exit_editmode, otherwise derivedmeshes for shared data corrupt T27765. */
-  /* Main now can store a '.blend' thumbnail, useful for background mode
-   * or thumbnail customization. */
-  main_thumb = thumb = bmain->blen_thumb;
-  if (BLI_thread_is_main() && U.file_preview_type != USER_FILE_PREVIEW_NONE) {
-
-    int file_preview_type = U.file_preview_type;
-
-    if (file_preview_type == USER_FILE_PREVIEW_AUTO) {
-      Scene *scene = CTX_data_scene(C);
-      bool do_render = (scene != NULL && scene->camera != NULL &&
-                        (BKE_screen_find_big_area(CTX_wm_screen(C), SPACE_VIEW3D, 0) != NULL));
-      file_preview_type = do_render ? USER_FILE_PREVIEW_CAMERA : USER_FILE_PREVIEW_SCREENSHOT;
-    }
-
-    switch (file_preview_type) {
-      case USER_FILE_PREVIEW_SCREENSHOT: {
-        ibuf_thumb = blend_file_thumb_from_screenshot(C, &thumb);
-        break;
+  if (U.file_preview_type != USER_FILE_PREVIEW_NONE) {
+    /* Blend file thumbnail.
+     *
+     * - Save before exiting edit-mode, otherwise evaluated-mesh for shared data gets corrupted.
+     *   See T27765.
+     * - Main can store a '.blend' thumbnail,
+     *   useful for background-mode or thumbnail customization.
+     */
+    main_thumb = thumb = bmain->blen_thumb;
+    if (thumb != NULL) {
+      /* In case we are given a valid thumbnail data, just generate image from it. */
+      ibuf_thumb = BKE_main_thumbnail_to_imbuf(NULL, thumb);
+    }
+    else if (BLI_thread_is_main()) {
+      int file_preview_type = U.file_preview_type;
+
+      if (file_preview_type == USER_FILE_PREVIEW_AUTO) {
+        Scene *scene = CTX_data_scene(C);
+        bool do_render = (scene != NULL && scene->camera != NULL &&
+                          (BKE_screen_find_big_area(CTX_wm_screen(C), SPACE_VIEW3D, 0) != NULL));
+        file_preview_type = do_render ? USER_FILE_PREVIEW_CAMERA : USER_FILE_PREVIEW_SCREENSHOT;
       }
-      case USER_FILE_PREVIEW_CAMERA: {
-        ibuf_thumb = blend_file_thumb_from_camera(C, CTX_data_scene(C), CTX_wm_screen(C), &thumb);
-        break;
+
+      switch (file_preview_type) {
+        case USER_FILE_PREVIEW_SCREENSHOT: {
+          ibuf_thumb = blend_file_thumb_from_screenshot(C, &thumb);
+          break;
+        }
+        case USER_FILE_PREVIEW_CAMERA: {
+          ibuf_thumb = blend_file_thumb_from_camera(
+              C, CTX_data_scene(C), CTX_wm_screen(C), &thumb);
+          break;
+        }
+        default:
+          BLI_assert_unreachable();
       }
-      default:
-        BLI_assert_unreachable();
     }
   }