tests/fuzzers: move fuzzers into native packages (#28467)

This PR moves our fuzzers from tests/fuzzers into whatever their respective 'native' package is.

The historical reason why they were placed in an external location, is that when they were based on go-fuzz, they could not be "hidden" via the _test.go prefix. So in order to shove them away from the go-ethereum "production code", they were put aside.

But now we've rewritten them to be based on golang testing, and thus can be brought back. I've left (in tests/) the ones that are not production (bls128381), require non-standard imports (secp requires btcec, bn256 requires gnark/google/cloudflare deps).

This PR also adds a fuzzer for precompiled contracts, because why not.

This PR utilizes a newly rewritten replacement for go-118-fuzz-build, namely gofuzz-shim, which utilises the inputs from the fuzzing engine better.

core/vm/contracts_fuzz_test.go

@@ -0,0 +1,44 @@
+// Copyright 2023 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+func FuzzPrecompiledContracts(f *testing.F) {
+	// Create list of addresses
+	var addrs []common.Address
+	for k := range allPrecompiles {
+		addrs = append(addrs, k)
+	}
+	f.Fuzz(func(t *testing.T, addr uint8, input []byte) {
+		a := addrs[int(addr)%len(addrs)]
+		p := allPrecompiles[a]
+		gas := p.RequiredGas(input)
+		if gas > 10_000_000 {
+			return
+		}
+		inWant := string(input)
+		RunPrecompiledContract(p, input, gas)
+		if inHave := string(input); inWant != inHave {
+			t.Errorf("Precompiled %v modified input data", a)
+		}
+	})
+}

core/vm/runtime/runtime_fuzz_test.go

@@ -0,0 +1,29 @@
+// Copyright 2023 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package runtime
+
+import (
+	"testing"
+)
+
+func FuzzVmRuntime(f *testing.F) {
+	f.Fuzz(func(t *testing.T, code, input []byte) {
+		Execute(code, input, &Config{
+			GasLimit: 12000000,
+		})
+	})
+}