Move more internal fuzzers to public.

Change-Id: Idde75f374264666e4c54a17b1606464ad5d00d9c

tests/fuzzer/imageio_fuzzer.cc

@@ -0,0 +1,81 @@
+// Copyright 2024 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+// Fuzzing of libwebp's image readers
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <iostream>
+#include <tiffio.h>
+
+#include "imageio/image_dec.h"
+#include "imageio/metadata.h"
+#include "src/webp/encode.h"
+#include "tests/fuzzer/fuzz_utils.h"
+
+namespace {
+
+void TestReader(const uint8_t *data, size_t size, WebPImageReader reader,
+                bool keep_alpha, bool use_argb) {
+  WebPPicture pic;
+  if (!WebPPictureInit(&pic)) {
+    std::cerr << "WebPPictureInit failed" << std::endl;
+    abort();
+  }
+  Metadata metadata;
+  MetadataInit(&metadata);
+  pic.use_argb = use_argb ? 1 : 0;
+
+  if (!fuzz_utils::IsImageTooBig(data, size)) {
+    (void)(*reader)(data, size, &pic, keep_alpha ? 1 : 0, &metadata);
+  }
+  WebPPictureFree(&pic);
+  MetadataFree(&metadata);
+}
+
+constexpr WebPInputFileFormat kUnknown = WEBP_UNSUPPORTED_FORMAT;
+
+void Decode(std::string_view arbitrary_bytes, WebPInputFileFormat format,
+            bool keep_alpha, bool use_argb) {
+  if (format == kUnknown || format == WEBP_TIFF_FORMAT) {
+    TIFFSetErrorHandler(NULL);    // libtiff can be verbose about errors.
+    TIFFSetWarningHandler(NULL);  // Silence it to avoid timeouts.
+  }
+
+  const uint8_t *data =
+      reinterpret_cast<const uint8_t *>(arbitrary_bytes.data());
+  const size_t size = arbitrary_bytes.size();
+  if (format == kUnknown) {
+    (void)WebPGuessImageType(data, size);  // shouldn't fail
+    TestReader(data, size, WebPGuessImageReader(data, size), keep_alpha,
+               use_argb);
+  } else {
+    TestReader(data, size, WebPGetImageReader(format), keep_alpha, use_argb);
+  }
+}
+
+FUZZ_TEST(ImageIOSuite, Decode)
+    .WithDomains(
+        fuzztest::String()
+            .WithMaxSize(fuzz_utils::kMaxWebPFileSize + 1),
+        fuzztest::ElementOf<WebPInputFileFormat>(
+            {WEBP_PNG_FORMAT, WEBP_JPEG_FORMAT, WEBP_TIFF_FORMAT,
+             WEBP_WEBP_FORMAT, WEBP_PNM_FORMAT, kUnknown}),
+        /*keep_alpha=*/fuzztest::Arbitrary<bool>(),
+        /*use_argb=*/fuzztest::Arbitrary<bool>());
+
+}  // namespace