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C++ API tweaks (part 2) #449

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Nov 8, 2019
Merged

C++ API tweaks (part 2) #449

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8fb2105
cpp: Reverse order of VM and Host definitions
chfast Nov 6, 2019
a647969
test: Add basic unit tests for previously unused API
chfast Nov 6, 2019
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230 changes: 112 additions & 118 deletions include/evmc/evmc.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -334,118 +334,6 @@ class result : private evmc_result
}
};

class Host;

/// @copybrief evmc_vm
///
/// This is a RAII wrapper for evmc_vm and objects of this type
/// automatically destroys the VM instance.
class VM
{
public:
VM() noexcept = default;

/// Converting constructor from evmc_vm.
explicit VM(evmc_vm* vm) noexcept : m_instance{vm} {}

/// Destructor responsible for automatically destroying the VM instance.
~VM() noexcept
{
if (m_instance)
m_instance->destroy(m_instance);
}

VM(const VM&) = delete;
VM& operator=(const VM&) = delete;

/// Move constructor.
VM(VM&& other) noexcept : m_instance{other.m_instance} { other.m_instance = nullptr; }

/// Move assignment operator.
VM& operator=(VM&& other) noexcept
{
this->~VM();
m_instance = other.m_instance;
other.m_instance = nullptr;
return *this;
}

/// The constructor that captures a VM instance and configures the instance
/// with the provided list of options.
inline VM(evmc_vm* vm,
std::initializer_list<std::pair<const char*, const char*>> options) noexcept;

/// Checks if contains a valid pointer to the VM instance.
explicit operator bool() const noexcept { return m_instance != nullptr; }

/// Checks whenever the VM instance is ABI compatible with the current EVMC API.
bool is_abi_compatible() const noexcept { return m_instance->abi_version == EVMC_ABI_VERSION; }

/// @copydoc evmc_vm::name
char const* name() const noexcept { return m_instance->name; }

/// @copydoc evmc_vm::version
char const* version() const noexcept { return m_instance->version; }

/// @copydoc evmc::vm::get_capabilities
evmc_capabilities_flagset get_capabilities() const noexcept
{
return m_instance->get_capabilities(m_instance);
}

/// @copydoc evmc_set_option()
evmc_set_option_result set_option(const char name[], const char value[]) noexcept
{
return evmc_set_option(m_instance, name, value);
}

/// @copydoc evmc_execute()
result execute(const evmc_host_interface& host,
evmc_host_context* ctx,
evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept
{
return result{m_instance->execute(m_instance, &host, ctx, rev, &msg, code, code_size)};
}

/// Convenient variant of the VM::execute() that takes reference to evmc::Host class.
inline result execute(Host& host,
evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept;

/// Executes code without the Host context.
///
/// The same as
/// execute(const evmc_host_interface&, evmc_host_context*, evmc_revision,
/// const evmc_message&, const uint8_t*, size_t),
/// but without providing the Host context and interface.
/// This method is for experimental precompiles support where execution is
/// guaranteed not to require any Host access.
result execute(evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept
{
return result{
m_instance->execute(m_instance, nullptr, nullptr, rev, &msg, code, code_size)};
}

private:
evmc_vm* m_instance = nullptr;
};

inline VM::VM(evmc_vm* vm,
std::initializer_list<std::pair<const char*, const char*>> options) noexcept
: m_instance{vm}
{
for (const auto& option : options)
set_option(option.first, option.second);
}


/// The EVMC Host interface
class HostInterface
Expand Down Expand Up @@ -596,6 +484,7 @@ class HostContext : public HostInterface
}
};


/// Abstract class to be used by Host implementations.
///
/// When implementing EVMC Host, you can directly inherit from the evmc::Host class.
Expand Down Expand Up @@ -628,13 +517,118 @@ class Host : public HostInterface
};


inline result VM::execute(Host& host,
evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept
/// @copybrief evmc_vm
///
/// This is a RAII wrapper for evmc_vm, and object of this type
/// automatically destroys the VM instance.
class VM
{
public:
VM() noexcept = default;

/// Converting constructor from evmc_vm.
explicit VM(evmc_vm* vm) noexcept : m_instance{vm} {}

/// Destructor responsible for automatically destroying the VM instance.
~VM() noexcept
{
if (m_instance)
m_instance->destroy(m_instance);
}

VM(const VM&) = delete;
VM& operator=(const VM&) = delete;

/// Move constructor.
VM(VM&& other) noexcept : m_instance{other.m_instance} { other.m_instance = nullptr; }

/// Move assignment operator.
VM& operator=(VM&& other) noexcept
{
this->~VM();
m_instance = other.m_instance;
other.m_instance = nullptr;
return *this;
}

/// The constructor that captures a VM instance and configures the instance
/// with the provided list of options.
inline VM(evmc_vm* vm,
std::initializer_list<std::pair<const char*, const char*>> options) noexcept;

/// Checks if contains a valid pointer to the VM instance.
explicit operator bool() const noexcept { return m_instance != nullptr; }

/// Checks whenever the VM instance is ABI compatible with the current EVMC API.
bool is_abi_compatible() const noexcept { return m_instance->abi_version == EVMC_ABI_VERSION; }

/// @copydoc evmc_vm::name
char const* name() const noexcept { return m_instance->name; }

/// @copydoc evmc_vm::version
char const* version() const noexcept { return m_instance->version; }

/// @copydoc evmc::vm::get_capabilities
evmc_capabilities_flagset get_capabilities() const noexcept
{
return m_instance->get_capabilities(m_instance);
}

/// @copydoc evmc_set_option()
evmc_set_option_result set_option(const char name[], const char value[]) noexcept
{
return evmc_set_option(m_instance, name, value);
}

/// @copydoc evmc_execute()
result execute(const evmc_host_interface& host,
evmc_host_context* ctx,
evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept
{
return result{m_instance->execute(m_instance, &host, ctx, rev, &msg, code, code_size)};
}

/// Convenient variant of the VM::execute() that takes reference to evmc::Host class.
result execute(Host& host,
evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept
{
return execute(Host::get_interface(), host.to_context(), rev, msg, code, code_size);
}

/// Executes code without the Host context.
///
/// The same as
/// execute(const evmc_host_interface&, evmc_host_context*, evmc_revision,
/// const evmc_message&, const uint8_t*, size_t),
/// but without providing the Host context and interface.
/// This method is for experimental precompiles support where execution is
/// guaranteed not to require any Host access.
result execute(evmc_revision rev,
const evmc_message& msg,
const uint8_t* code,
size_t code_size) noexcept
{
return result{
m_instance->execute(m_instance, nullptr, nullptr, rev, &msg, code, code_size)};
}

private:
evmc_vm* m_instance = nullptr;
};

inline VM::VM(evmc_vm* vm,
std::initializer_list<std::pair<const char*, const char*>> options) noexcept
: m_instance{vm}
{
return execute(Host::get_interface(), host.to_context(), rev, msg, code, code_size);
// This constructor is implemented outside of the class definition to workaround a doxygen bug.
for (const auto& option : options)
set_option(option.first, option.second);
}


Expand Down
71 changes: 71 additions & 0 deletions test/unittests/test_cpp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,47 @@
#include <map>
#include <unordered_map>

class NullHost : public evmc::Host
{
public:
bool account_exists(const evmc::address&) noexcept final { return false; }

evmc::bytes32 get_storage(const evmc::address&, const evmc::bytes32&) noexcept final
{
return {};
}

evmc_storage_status set_storage(const evmc::address&,
const evmc::bytes32&,
const evmc::bytes32&) noexcept final
{
return {};
}

evmc::uint256be get_balance(const evmc::address&) noexcept final { return {}; }

size_t get_code_size(const evmc::address&) noexcept final { return 0; }

evmc::bytes32 get_code_hash(const evmc::address&) noexcept final { return {}; }

size_t copy_code(const evmc::address&, size_t, uint8_t*, size_t) noexcept final { return 0; }

void selfdestruct(const evmc::address&, const evmc::address&) noexcept final {}

evmc::result call(const evmc_message&) noexcept final { return evmc::result{evmc_result{}}; }

evmc_tx_context get_tx_context() noexcept final { return {}; }

evmc::bytes32 get_block_hash(int64_t) noexcept final { return {}; }

void emit_log(const evmc::address&,
const uint8_t*,
size_t,
const evmc::bytes32[],
size_t) noexcept final
{}
};

TEST(cpp, address)
{
evmc::address a;
Expand Down Expand Up @@ -285,6 +326,23 @@ TEST(cpp, vm_set_option)
EXPECT_EQ(vm.set_option("1", "2"), EVMC_SET_OPTION_INVALID_NAME);
}

TEST(cpp, vm_set_option_in_constructor)
{
static int num_calls = 0;
const auto set_option_method = [](evmc_vm* /*unused*/, const char* name, const char* value) {
++num_calls;
EXPECT_STREQ(name, "o");
EXPECT_EQ(value, std::to_string(num_calls));
return EVMC_SET_OPTION_INVALID_NAME;
};

evmc_vm raw{EVMC_ABI_VERSION, "", "", nullptr, nullptr, nullptr, set_option_method};
raw.destroy = [](evmc_vm*) {};

const auto vm = evmc::VM{&raw, {{"o", "1"}, {"o", "2"}}};
EXPECT_EQ(num_calls, 2);
}

TEST(cpp, vm_null)
{
evmc::VM vm;
Expand Down Expand Up @@ -365,6 +423,19 @@ TEST(cpp, vm_execute_precompiles)
EXPECT_TRUE(std::equal(input.begin(), input.end(), res.output_data));
}

TEST(cpp, vm_execute_with_null_host)
{
// This tests only if the used VM::execute() overload is at least implemented.
// We know that the example VM will not use the host context in this case.

auto host = NullHost{};

auto vm = evmc::VM{evmc_create_example_vm()};
evmc_message msg{};
auto res = vm.execute(host, EVMC_MAX_REVISION, msg, nullptr, 0);
EXPECT_EQ(res.status_code, EVMC_FAILURE);
}

TEST(cpp, host)
{
// Use example host to execute all methods from the C++ host wrapper.
Expand Down