Test: Added fuzz test for BlobUtil::readNBytes

src/standalones/s_bmqfuzz/package/s_bmqfuzz.mem

@@ -1,4 +1,5 @@
 s_bmqfuzz_bmqt_uri.fuzz
+s_bmqfuzz_bmqu_blobutil_readnbytes.fuzz
 s_bmqfuzz_bmqu_stringutil_match.fuzz
 s_bmqfuzz_eval.fuzz
 s_bmqfuzz_parseutil.fuzz

src/standalones/s_bmqfuzz/s_bmqfuzz_bmqu_blobutil_readnbytes.fuzz.cpp

@@ -0,0 +1,69 @@
+// Copyright 2026 Bloomberg Finance L.P.
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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.
+
+#include <fuzzer/FuzzedDataProvider.h>
+
+#include <bmqu_blob.h>
+
+#include <bdlbb_blob.h>
+#include <bsl_cstring.h>
+#include <bsl_memory.h>
+#include <bsl_vector.h>
+
+using namespace BloombergLP;
+
+namespace {
+
+const int k_MAX_BUFFERS  = 32;
+const int k_MAX_BUF_SIZE = 512;
+const int k_MAX_LENGTH   = 64 * 1024;
+
+}
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
+{
+    FuzzedDataProvider provider(data, size);
+
+    bslma::Allocator* alloc = bslma::Default::allocator();
+    bdlbb::Blob       blob(alloc);
+
+    const int numBuffers = provider.ConsumeIntegralInRange(0, k_MAX_BUFFERS);
+    for (int i = 0; i < numBuffers; ++i) {
+        const int bufSize = provider.ConsumeIntegralInRange(1, k_MAX_BUF_SIZE);
+        bsl::shared_ptr<char> bufData(
+            static_cast<char*>(alloc->allocate(bufSize)),
+            alloc);
+        const std::vector<uint8_t> bytes = provider.ConsumeBytes<uint8_t>(
+            bufSize);
+        bsl::memcpy(bufData.get(), bytes.data(), bytes.size());
+        blob.appendDataBuffer(bdlbb::BlobBuffer(bufData, bufSize));
+    }
+
+    blob.setLength(provider.ConsumeIntegralInRange(0, blob.length()));
+
+    const int startBuffer = provider.ConsumeIntegralInRange(-2,
+                                                            numBuffers + 2);
+    const int startByte   = provider.ConsumeIntegralInRange(-2,
+                                                          k_MAX_BUF_SIZE + 2);
+    const int length      = provider.ConsumeIntegralInRange(0, k_MAX_LENGTH);
+    bsl::vector<char> out(length > 0 ? length : 1, alloc);
+
+    bmqu::BlobUtil::readNBytes(out.data(),
+                               blob,
+                               bmqu::BlobPosition(startBuffer, startByte),
+                               length);
+
+    return 0;
+}