fuzz: parse the command line arguments in fuzz tests

Retrieve the command line arguments from the fuzzer and save them for
later retrieval by `BasicTestingSetup` so that we gain extra flexibility
of passing any config options on the test command line, e.g.:

```
FUZZ=addrman ./src/test/fuzz/fuzz --checkaddrman=5
```

A fuzz test should call `MakeNoLogFileContext<>()` in its initialize
function in order to invoke the constructor of `BasicTestingSetup`,
which sets `gArgs`.
This commit is contained in:
Vasil Dimov 2021-10-26 17:26:16 +02:00
parent 92a0f7e58d
commit 6f7c7567c5
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2 changed files with 32 additions and 1 deletions

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@ -71,6 +71,15 @@ block^@M-^?M-^?M-^?M-^?M-^?nM-^?M-^?
In this case the fuzzer managed to create a `block` message which when passed to `ProcessMessage(...)` increased coverage.
It is possible to specify `bitcoind` arguments to the `fuzz` executable.
Depending on the test, they may be ignored or consumed and alter the behavior
of the test. Just make sure to use double-dash to distinguish them from the
fuzzer's own arguments:
```sh
$ FUZZ=address_deserialize_v2 src/test/fuzz/fuzz -runs=1 fuzz_seed_corpus/address_deserialize_v2 --checkaddrman=5 --printtoconsole=1
```
## Fuzzing corpora
The project's collection of seed corpora is found in the [`bitcoin-core/qa-assets`](https://github.com/bitcoin-core/qa-assets) repo.

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@ -20,7 +20,28 @@
const std::function<void(const std::string&)> G_TEST_LOG_FUN{};
const std::function<std::vector<const char*>()> G_TEST_COMMAND_LINE_ARGUMENTS{};
/**
* A copy of the command line arguments that start with `--`.
* First `LLVMFuzzerInitialize()` is called, which saves the arguments to `g_args`.
* Later, depending on the fuzz test, `G_TEST_COMMAND_LINE_ARGUMENTS()` may be
* called by `BasicTestingSetup` constructor to fetch those arguments and store
* them in `BasicTestingSetup::m_node::args`.
*/
static std::vector<const char*> g_args;
static void SetArgs(int argc, char** argv) {
for (int i = 1; i < argc; ++i) {
// Only take into account arguments that start with `--`. The others are for the fuzz engine:
// `fuzz -runs=1 fuzz_seed_corpus/address_deserialize_v2 --checkaddrman=5`
if (strlen(argv[i]) > 2 && argv[i][0] == '-' && argv[i][1] == '-') {
g_args.push_back(argv[i]);
}
}
}
const std::function<std::vector<const char*>()> G_TEST_COMMAND_LINE_ARGUMENTS = []() {
return g_args;
};
std::map<std::string_view, std::tuple<TypeTestOneInput, TypeInitialize, TypeHidden>>& FuzzTargets()
{
@ -98,6 +119,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
// This function is used by libFuzzer
extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv)
{
SetArgs(*argc, *argv);
initialize();
return 0;
}