LibGfx/WebPLoader: Survive calling loop_count() before other accessors

Fixes `animation` asserting when reading a webp input. (The other order of operations is still covered by TestImageWriter.cpp.)
nico · Jun 3, 2024 · de1318d · de1318d
1 parent 1e4a78e
commit de1318d
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/Tests/LibGfx/TestImageDecoder.cpp b/Tests/LibGfx/TestImageDecoder.cpp
@@ -1381,9 +1381,9 @@ TEST_CASE(test_webp_extended_lossless_animated)
     EXPECT(Gfx::WebPImageDecoderPlugin::sniff(file->bytes()));
     auto plugin_decoder = TRY_OR_FAIL(Gfx::WebPImageDecoderPlugin::create(file->bytes()));
 
+    EXPECT_EQ(plugin_decoder->loop_count(), 42u);
     EXPECT_EQ(plugin_decoder->frame_count(), 8u);
     EXPECT(plugin_decoder->is_animated());
-    EXPECT_EQ(plugin_decoder->loop_count(), 42u);
 
     EXPECT_EQ(plugin_decoder->size(), Gfx::IntSize(990, 1050));
 

diff --git a/Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp
@@ -639,6 +639,11 @@ size_t WebPImageDecoderPlugin::loop_count()
     if (!is_animated())
         return 0;
 
+    if (m_context->state < WebPLoadingContext::State::ChunksDecoded) {
+        if (set_error(decode_webp_chunks(*m_context)))
+            return 0;
+    }
+
     if (m_context->state < WebPLoadingContext::State::AnimationFrameChunksDecoded) {
         if (set_error(decode_webp_animation_frame_chunks(*m_context)))
             return 0;