Wait for decoding jobs to finish before returning.

If an early job returns an error and the method returns, the remaining jobs
continue to run and might try to access objects that no longer exist.

Author: fancycode

libheif/image-items/grid.cc

@@ -227,6 +227,18 @@ Result<std::shared_ptr<HeifPixelImage>> ImageItem_Grid::decode_compressed_image(
   }
 }
 
+#if ENABLE_PARALLEL_TILE_DECODING
+static void wait_for_jobs(std::deque<std::future<Error> >* jobs) {
+  if (jobs->empty()) {
+    return;
+  }
+
+  while (!jobs->empty()) {
+    jobs->front().get();
+    jobs->pop_front();
+  }
+}
+#endif
 
 Result<std::shared_ptr<HeifPixelImage>> ImageItem_Grid::decode_full_grid_image(const heif_decoding_options& options) const
 {
@@ -372,11 +384,11 @@ Result<std::shared_ptr<HeifPixelImage>> ImageItem_Grid::decode_full_grid_image(c
 
       if (errs.size() >= (size_t) get_context()->get_max_decoding_threads()) {
         Error e = errs.front().get();
+        errs.pop_front();
         if (e) {
+          wait_for_jobs(&errs);
           return e;
         }
-
-        errs.pop_front();
       }
 
 
@@ -402,11 +414,11 @@ Result<std::shared_ptr<HeifPixelImage>> ImageItem_Grid::decode_full_grid_image(c
 
     while (!errs.empty()) {
       Error e = errs.front().get();
+      errs.pop_front();
       if (e) {
+        wait_for_jobs(&errs);
         return e;
       }
-
-      errs.pop_front();
     }
   }
 #endif