tests: Add fuzzing harness for CAutoFile (streams.h)

Author: practicalswift

src/Makefile.test.include

@@ -10,6 +10,7 @@ FUZZ_TARGETS = \
   test/fuzz/addrman_deserialize \
   test/fuzz/asmap \
   test/fuzz/asmap_direct \
+  test/fuzz/autofile \
   test/fuzz/banentry_deserialize \
   test/fuzz/banman \
   test/fuzz/base_encode_decode \
@@ -350,6 +351,12 @@ test_fuzz_asmap_direct_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_asmap_direct_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_asmap_direct_SOURCES = test/fuzz/asmap_direct.cpp
 
+test_fuzz_autofile_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_autofile_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_autofile_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_autofile_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_autofile_SOURCES = test/fuzz/autofile.cpp
+
 test_fuzz_banentry_deserialize_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) -DBANENTRY_DESERIALIZE=1
 test_fuzz_banentry_deserialize_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_banentry_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/test/fuzz/autofile.cpp

@@ -0,0 +1,72 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <optional.h>
+#include <streams.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+
+#include <array>
+#include <cstdint>
+#include <iostream>
+#include <optional>
+#include <string>
+#include <vector>
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+    FuzzedAutoFileProvider fuzzed_auto_file_provider = ConsumeAutoFile(fuzzed_data_provider);
+    CAutoFile auto_file = fuzzed_auto_file_provider.open();
+    while (fuzzed_data_provider.ConsumeBool()) {
+        switch (fuzzed_data_provider.ConsumeIntegralInRange<int>(0, 5)) {
+        case 0: {
+            std::array<uint8_t, 4096> arr{};
+            try {
+                auto_file.read((char*)arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096));
+            } catch (const std::ios_base::failure&) {
+            }
+            break;
+        }
+        case 1: {
+            const std::array<uint8_t, 4096> arr{};
+            try {
+                auto_file.write((const char*)arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096));
+            } catch (const std::ios_base::failure&) {
+            }
+            break;
+        }
+        case 2: {
+            try {
+                auto_file.ignore(fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096));
+            } catch (const std::ios_base::failure&) {
+            }
+            break;
+        }
+        case 3: {
+            auto_file.fclose();
+            break;
+        }
+        case 4: {
+            ReadFromStream(fuzzed_data_provider, auto_file);
+            break;
+        }
+        case 5: {
+            WriteToStream(fuzzed_data_provider, auto_file);
+            break;
+        }
+        }
+    }
+    (void)auto_file.Get();
+    (void)auto_file.GetType();
+    (void)auto_file.GetVersion();
+    (void)auto_file.IsNull();
+    if (fuzzed_data_provider.ConsumeBool()) {
+        FILE* f = auto_file.release();
+        if (f != nullptr) {
+            fclose(f);
+        }
+    }
+}