Merge pull request #1284 from sleuthkit/img_writer_delay

Added delay into image writer to not starve other readers

tsk/img/img_writer.cpp

@@ -575,8 +575,15 @@ static TSK_RETVAL_ENUM tsk_img_writer_finish_image(TSK_IMG_WRITER* img_writer) {
                     return TSK_ERR;
                 }
                 /* Using tsk_img_read here to make sure we get the lock */
-                tsk_img_read(img_writer->img_info, offset, buffer, TSK_IMG_INFO_CACHE_LEN);
+                if (tsk_img_read(img_writer->img_info, offset, buffer, TSK_IMG_INFO_CACHE_LEN) < 0) {
+                    // this usually happens when the device has been unplugged
+                    return TSK_ERR;
+                }
             }
+            /* In Autopsy, tsk_img_writer_finish_image() was starving other threads that were trying to do
+             * basic reads and made the app impossible to use. Add the short sleep to give
+             * other threads a chance to get the underlying locks. */
+            Sleep(1);
         }
     }