Update Decode() for ImageDecoder API 3.1.0

src/MPOPicture.cpp

@@ -154,17 +154,43 @@ bool MPOPicture::LoadImageFromMemory(const std::string& mimetype,
 }
 
 bool MPOPicture::Decode(uint8_t* pixels,
+                        size_t pixelBufferSize,
                         unsigned int width,
                         unsigned int height,
                         unsigned int pitch,
                         ADDON_IMG_FMT format)
 {
+  // The copy loop below writes B,G,R and only fills the fourth byte for
+  // A8R8G8B8, so that is the only format implemented here.
+  if (format != ADDON_IMG_FMT_A8R8G8B8)
+  {
+    kodi::Log(ADDON_LOG_ERROR, "%s: Unsupported target format (%d)", __func__,
+              static_cast<int>(format));
+    return false;
+  }
+
   size_t image = 0;
   while (image < m_images)
   {
     mpo_start_decompress(&m_mpoinfo);
     JSAMPARRAY buffer;
     int row_stride = m_mpoinfo.cinfo.cinfo.output_width * m_mpoinfo.cinfo.cinfo.output_components;
+
+    // Mirrors the destination offset in the loop below exactly - the integer
+    // division must be applied in the same order or an odd m_width
+    // underestimates the reach for images after the first.
+    const size_t tileOffset = image * m_width / 2 * 4;
+    if (m_height == 0 || row_stride <= 0 ||
+        static_cast<size_t>(m_height - 1) * pitch + tileOffset +
+                static_cast<size_t>(row_stride / 3) * 4 >
+            pixelBufferSize)
+    {
+      kodi::Log(ADDON_LOG_ERROR, "%s: Output buffer too small for image %zu of %ux%u at pitch %u",
+                __func__, image, m_width, m_height, pitch);
+      mpo_finish_decompress(&m_mpoinfo);
+      return false;
+    }
+
     size_t lines = 0;
     while (lines < m_height)
     {

src/MPOPicture.h

@@ -28,6 +28,7 @@ class ATTR_DLL_LOCAL MPOPicture : public kodi::addon::CInstanceImageDecoder
                            unsigned int& width,
                            unsigned int& height) override;
   bool Decode(uint8_t* pixels,
+              size_t pixelBufferSize,
               unsigned int width,
               unsigned int height,
               unsigned int pitch,