From d9dc42fab5a0869e51df3b60c408555e0ab69d0a Mon Sep 17 00:00:00 2001
From: Erik Biederstadt <biederstadterik@gmail.com>
Date: Mon, 17 May 2021 15:45:15 -0600
Subject: [PATCH] GLTeapot: Adds additional error checking when loading files

- If the 3D file contains no vertices then an error is raised
- If the file is not an OBJ file then an error is raised
---
 Userland/Demos/GLTeapot/WavefrontOBJLoader.cpp |  5 +++++
 Userland/Demos/GLTeapot/main.cpp               | 16 ++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Userland/Demos/GLTeapot/WavefrontOBJLoader.cpp b/Userland/Demos/GLTeapot/WavefrontOBJLoader.cpp
index 08fa574447..891f13dc8f 100644
--- a/Userland/Demos/GLTeapot/WavefrontOBJLoader.cpp
+++ b/Userland/Demos/GLTeapot/WavefrontOBJLoader.cpp
@@ -66,6 +66,11 @@ RefPtr<Mesh> WavefrontOBJLoader::load(const String& fname)
         }
     }
 
+    if (vertices.is_empty()) {
+        dbgln("Wavefront: Failed to read any data from 3D file: {}", fname);
+        return nullptr;
+    }
+
     dbgln("Wavefront: Done.");
     return adopt_ref(*new Mesh(vertices, triangles));
 }
diff --git a/Userland/Demos/GLTeapot/main.cpp b/Userland/Demos/GLTeapot/main.cpp
index 9a29cd0060..0e8f6a163d 100644
--- a/Userland/Demos/GLTeapot/main.cpp
+++ b/Userland/Demos/GLTeapot/main.cpp
@@ -102,7 +102,8 @@ void GLContextWidget::timer_event(Core::TimerEvent&)
     glMatrixMode(GL_MODELVIEW);
     glLoadMatrixf((float*)matrix.elements());
 
-    m_mesh->draw();
+    if (!m_mesh.is_null())
+        m_mesh->draw();
 
     m_context->present();
     update();
@@ -111,7 +112,12 @@ void GLContextWidget::timer_event(Core::TimerEvent&)
 bool GLContextWidget::load(const String& fname)
 {
     m_mesh = m_mesh_loader->load(fname);
-    return !m_mesh.is_null();
+    if (!m_mesh.is_null()) {
+        dbgln("GLTeapot: mesh has {} triangles.", m_mesh->triangle_count());
+        return true;
+    }
+
+    return false;
 }
 
 int main(int argc, char** argv)
@@ -159,6 +165,12 @@ int main(int argc, char** argv)
             return;
 
         auto file = Core::File::construct(open_path.value());
+
+        if (!file->filename().ends_with(".obj")) {
+            GUI::MessageBox::show(window, String::formatted("Opening \"{}\" failed: invalid file type", open_path.value()), "Error", GUI::MessageBox::Type::Error);
+            return;
+        }
+
         if (!file->open(Core::OpenMode::ReadOnly) && file->error() != ENOENT) {
             GUI::MessageBox::show(window, String::formatted("Opening \"{}\" failed: {}", open_path.value(), strerror(errno)), "Error", GUI::MessageBox::Type::Error);
             return;