Resolve #88

libraries/eosiolib/capi/eosio/action.h

@@ -168,6 +168,16 @@ uint64_t publication_time( void );
 __attribute__((eosio_wasm_import))
 capi_name current_receiver( void );
 
+/**
+ * Get the hash of the code currently published on the given account
+ * @param account Name of the account to hash the code of
+ * @param struct_version Version specifying the desired format of the returned struct
+ * @param result_buffer Buffer wherein the result should be written
+ * @param buffer_size Size in bytes of result_buffer
+ */
+ __attribute__((eosio_wasm_import))
+ uint32_t get_code_hash( uint64_t account, uint32_t struct_version, char* result_buffer, size_t buffer_size );
+
 /**
  * Set the action return value which will be included in the action_receipt
  * @brief Set the action return value

libraries/eosiolib/contracts/eosio/action.hpp

@@ -8,6 +8,7 @@
 #include "../../core/eosio/serialize.hpp"
 #include "../../core/eosio/datastream.hpp"
 #include "../../core/eosio/name.hpp"
+#include "../../core/eosio/fixed_bytes.hpp"
 #include "../../core/eosio/ignore.hpp"
 #include "../../core/eosio/time.hpp"
 
@@ -52,9 +53,23 @@ namespace eosio {
 
  __attribute__((eosio_wasm_import))
  uint64_t current_receiver();
+
+ __attribute__((eosio_wasm_import))
+ uint32_t get_code_hash( uint64_t account, uint32_t struct_version, char* result_buffer, size_t buffer_size );
  }
  };
 
+ struct code_hash_result {
+ unsigned_int struct_version;
+ uint64_t code_sequence;
+ checksum256 code_hash;
+ uint8_t vm_type;
+ uint8_t vm_version;
+
+ CDT_REFLECT(struct_version, code_sequence, code_hash, vm_type, vm_version);
+ EOSLIB_SERIALIZE(code_hash_result, (struct_version)(code_sequence)(code_hash)(vm_type)(vm_version));
+ };
+
  /**
  * @defgroup action Action
  * @ingroup contracts
@@ -150,6 +165,50 @@ namespace eosio {
  return name{internal_use_do_not_use::current_receiver()};
  }
 
+ /**
+ * Get the hash of the code currently published on the given account
+ * @param account Name of the account to hash the code of
+ * @param full_result Optional: If a full result struct is desired, a pointer to the struct to populate
+ * @return The SHA256 hash of the specified account's code
+ */
+ inline checksum256 get_code_hash( name account, code_hash_result* full_result = nullptr ) {
+ if (full_result == nullptr)
+ full_result = (code_hash_result*)alloca(sizeof(code_hash_result));
+ constexpr size_t max_stack_buffer_size = 50;
+
+ // Packed size of this struct will virtually always be less than the struct size; always less after padding
+ auto struct_buffer_size = sizeof(code_hash_result);
+ char* struct_buffer = (char*)alloca(struct_buffer_size);
+
+ using VersionType = decltype(code_hash_result::struct_version);
+ const VersionType STRUCT_VERSION = 0;
+ auto response_size =
+ internal_use_do_not_use::get_code_hash(account.value, STRUCT_VERSION, struct_buffer, struct_buffer_size);
+ // Safety check: in this case, response size should never exceed our buffer, but just in case...
+ bool buffer_on_heap = false;
+ if (response_size > struct_buffer_size) {
+ // Slow path: allocate an adequate buffer and try again
+ // No need to deallocate struct_buffer since it was alloca'd
+ if (response_size > max_stack_buffer_size) {
+ struct_buffer = (char*)malloc(response_size);
+ buffer_on_heap = true;
+ } else {
+ struct_buffer = (char*)alloca(response_size);
+ }
+ internal_use_do_not_use::get_code_hash(account.value, STRUCT_VERSION, struct_buffer, struct_buffer_size);
+ }
+
+ check(unpack<VersionType>(struct_buffer, struct_buffer_size) == STRUCT_VERSION,
+ "Hypervisor returned unexpected code hash struct version");
+ unpack(*full_result, struct_buffer, struct_buffer_size);
+
+ // If struct_buffer is heap allocated, we must free it
+ if (buffer_on_heap)
+ free(struct_buffer);
+
+ return full_result->code_hash;
+ }
+
  /**
  * Copy up to length bytes of current action data to the specified location
  *

tests/integration/contracts.hpp.in

@@ -22,5 +22,10 @@ namespace eosio::testing {
 
  static std::vector<uint8_t> crypto_primitives_test_wasm() { return read_wasm("${CMAKE_BINARY_DIR}/../unit/test_contracts/crypto_primitives_tests.wasm"); }
  static std::vector<char> crypto_primitives_test_abi() { return read_abi("${CMAKE_BINARY_DIR}/../unit/test_contracts/crypto_primitives_tests.abi"); }
+
+ static std::vector<uint8_t> get_code_hash_write_test_wasm() { return read_wasm("${CMAKE_BINARY_DIR}/../unit/test_contracts/get_code_hash_write.wasm"); }
+ static std::vector<char> get_code_hash_write_test_abi() { return read_abi("${CMAKE_BINARY_DIR}/../unit/test_contracts/get_code_hash_write.abi"); }
+ static std::vector<uint8_t> get_code_hash_read_test_wasm() { return read_wasm("${CMAKE_BINARY_DIR}/../unit/test_contracts/get_code_hash_read.wasm"); }
+ static std::vector<char> get_code_hash_read_test_abi() { return read_abi("${CMAKE_BINARY_DIR}/../unit/test_contracts/get_code_hash_read.abi"); }
  };
 } //ns eosio::testing

tests/integration/get_code_hash_tests.cpp

@@ -0,0 +1,46 @@
+#include <boost/test/unit_test.hpp>
+#include <eosio/testing/tester.hpp>
+#include <eosio/chain/abi_serializer.hpp>
+
+#include <Runtime/Runtime.h>
+
+#include <fc/variant_object.hpp>
+
+#include <contracts.hpp>
+
+using namespace eosio;
+using namespace eosio::testing;
+using namespace eosio::chain;
+using namespace fc;
+
+using mvo = fc::mutable_variant_object;
+
+struct code_hash {
+ uint64_t id;
+ fc::sha256 hash;
+ uint64_t primary_key() const { return id; }
+};
+FC_REFLECT(code_hash, (id)(hash))
+
+BOOST_AUTO_TEST_SUITE(get_code_hash_tests_suite)
+
+BOOST_FIXTURE_TEST_CASE( get_code_hash_tests, tester ) try {
+ create_accounts( { "test"_n } );
+ produce_block();
+
+ set_code( "test"_n, contracts::get_code_hash_write_test_wasm() );
+ set_abi( "test"_n, contracts::get_code_hash_write_test_abi().data() );
+
+ produce_blocks();
+ push_action("test"_n, "theaction"_n, "test"_n, mvo());
+ code_hash entry;
+ get_table_entry(entry, "test"_n, "test"_n, "code.hash"_n, 0);
+ wdump((entry.hash));
+
+ set_code( "test"_n, contracts::get_code_hash_read_test_wasm() );
+ produce_blocks();
+
+ push_action("test"_n, "theaction"_n, "test"_n, mvo());
+} FC_LOG_AND_RETHROW()
+
+BOOST_AUTO_TEST_SUITE_END()

tests/unit/test_contracts/CMakeLists.txt

@@ -7,6 +7,8 @@ add_contract(explicit_nested_tests explicit_nested_tests explicit_nested_tests.c
 add_contract(transfer_contract transfer_contract transfer.cpp)
 add_contract(minimal_tests minimal_tests minimal_tests.cpp)
 add_contract(crypto_primitives_tests crypto_primitives_tests crypto_primitives_tests.cpp)
+add_contract(get_code_hash_tests get_code_hash_write get_code_hash_write.cpp)
+add_contract(get_code_hash_tests get_code_hash_read get_code_hash_read.cpp)
 add_contract(capi_tests capi_tests capi/capi.c capi/action.c capi/chain.c capi/crypto.c capi/db.c capi/permission.c
  capi/print.c capi/privileged.c capi/system.c capi/transaction.c)
 

tests/unit/test_contracts/capi/action.c

@@ -13,5 +13,6 @@ void test_action( void ) {
  send_context_free_inline(NULL, 0);
  publication_time();
  current_receiver();
+ get_code_hash(0, 0, NULL, 0);
  set_action_return_value(NULL, 0);
 }

tests/unit/test_contracts/get_code_hash_read.cpp

@@ -0,0 +1,27 @@
+#include <eosio/eosio.hpp>
+#include <eosio/action.hpp>
+#include <eosio/name.hpp>
+
+#include "get_code_hash_table.hpp"
+
+class [[eosio::contract]] get_code_hash_tests : public contract {
+public:
+ using contract::contract;
+
+ using hash_table = multi_index<name("code.hash"), code_hash>;
+
+ // Read the old code's hash from database and verify new code's hash differs
+ [[eosio::action]]
+ void theaction() {
+ require_auth(get_self());
+ hash_table hashes(get_self(), get_self().value);
+
+ auto hash = get_code_hash(get_self());
+ check(hash != checksum256(), "Code hash should not be null");
+
+ auto record = hashes.get(0, "Unable to find recorded hash");
+ check(hash != record.hash, "Code hash has not changed");
+ eosio::print("Old hash: ", record.hash, "; new hash: ", hash);
+ }
+};
+

tests/unit/test_contracts/get_code_hash_table.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+using namespace eosio;
+
+TABLE code_hash {
+ uint64_t id;
+ checksum256 hash;
+ uint64_t primary_key() const { return id; }
+};
+

tests/unit/test_contracts/get_code_hash_write.cpp

@@ -0,0 +1,28 @@
+#include <eosio/eosio.hpp>
+#include <eosio/action.hpp>
+#include <eosio/name.hpp>
+
+#include "get_code_hash_table.hpp"
+
+class [[eosio::contract]] get_code_hash_tests : public contract {
+public:
+ using contract::contract;
+
+ using hash_table = multi_index<name("code.hash"), code_hash>;
+
+ // Write this code's hash to database
+ [[eosio::action]]
+ void theaction() {
+ require_auth(get_self());
+ hash_table hashes(get_self(), get_self().value);
+
+ auto hash = get_code_hash(get_self());
+ check(hash != checksum256(), "Code hash should not be null");
+
+ hashes.emplace(get_self(), [&hash](auto& t) {
+ t.id = 0;
+ t.hash = hash;
+ });
+ }
+};
+