Port the PoC for b/506387278 to libavif See https://github.com/webmproject/CrabbyAvif/pull/812. The bug doesn't affect libavif, but it is good to add the test to libavif's test suite. Bug: https://b.corp.google.com/issues/506387278

diff --git a/tests/data/README.md b/tests/data/README.md
index 0a370bd..8c7ede2 100644
--- a/tests/data/README.md
+++ b/tests/data/README.md

@@ -981,6 +981,14 @@
 
 Source: Random frames generated with libavif.
 
+### File [poc_b_506387278.avif](poc_b_506387278.avif)
+
+![](poc_b_506387278.avif)
+
+License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
+
+Source: https://b.corp.google.com/issues/506387278
+
 ### File [webp_logo_animated.y4m](webp_logo_animated.y4m)
 
 ![](webp_logo_animated.y4m)

diff --git a/tests/data/poc_b_506387278.avif b/tests/data/poc_b_506387278.avif
new file mode 100644
index 0000000..66b4380
--- /dev/null
+++ b/tests/data/poc_b_506387278.avif
Binary files differ

diff --git a/tests/gtest/avifdecodetest.cc b/tests/gtest/avifdecodetest.cc
index 699f01a..4921c32 100644
--- a/tests/gtest/avifdecodetest.cc
+++ b/tests/gtest/avifdecodetest.cc

@@ -3,6 +3,7 @@
 
 #include <iostream>
 #include <string>
+#include <vector>
 
 #include "avif/avif.h"
 #include "aviftest_helpers.h"
@@ -128,6 +129,59 @@
   EXPECT_FALSE(avifPeekCompatibleFileType(&input));
 }
 
+struct NonPersistentIO {
+  std::vector<uint8_t> data;
+  avifROData ro_data;
+};
+
+// Every read call will explicitly invalidate the pointer returned by the
+// previous read call to ensure non-persistent IO.
+avifResult NonPersistentRead(struct avifIO* io, uint32_t flags, uint64_t offset,
+                             size_t size, avifROData* out) {
+  NonPersistentIO* io_data = reinterpret_cast<NonPersistentIO*>(io->data);
+  if (flags != 0 || offset > io_data->ro_data.size) {
+    return AVIF_RESULT_IO_ERROR;
+  }
+  uint64_t available_size = io_data->ro_data.size - offset;
+  if (size > available_size) {
+    size = static_cast<size_t>(available_size);
+  }
+  // Clear the existing vector.
+  std::vector<uint8_t>().swap(io_data->data);
+  // Copy new data into the vector.
+  io_data->data.reserve(size);
+  io_data->data.assign(io_data->ro_data.data + offset,
+                       io_data->ro_data.data + offset + size);
+  // Set the output.
+  out->data = io_data->data.data();
+  out->size = size;
+  return AVIF_RESULT_OK;
+}
+
+TEST(AvifDecodeTest, NonPersistentIOBug506387278) {
+  const testutil::AvifRwData avif =
+      testutil::ReadFile(std::string(data_path) + "poc_b_506387278.avif");
+  NonPersistentIO io_data;
+  io_data.ro_data = {/*.data=*/avif.data, /*.size=*/avif.size};
+  avifIO io = {/*.destroy=*/nullptr,
+               /*.read=*/NonPersistentRead,
+               /*.write=*/nullptr,
+               /*.sizeHint=*/avif.size,
+               /*.persistent=*/false,
+               /*.data=*/&io_data};
+  // |io| must outlive the decoder.
+  DecoderPtr decoder(avifDecoderCreate());
+  ASSERT_NE(decoder, nullptr);
+  avifDecoderSetIO(decoder.get(), &io);
+  ASSERT_EQ(avifDecoderParse(decoder.get()), AVIF_RESULT_OK);
+  EXPECT_EQ(decoder->imageSequenceTrackPresent, AVIF_TRUE);
+  EXPECT_EQ(decoder->imageCount, 2);
+  if (testutil::Av1DecoderAvailable()) {
+    EXPECT_EQ(avifDecoderNextImage(decoder.get()), AVIF_RESULT_OK);
+    EXPECT_EQ(avifDecoderNextImage(decoder.get()), AVIF_RESULT_OK);
+  }
+}
+
 }  // namespace
 }  // namespace avif