Ref #88: Implement wrapper for get_code_hash

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

@@ -9,6 +9,7 @@
 #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"
 
@@ -48,9 +49,23 @@ 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
@@ -146,6 +161,30 @@ 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));
+
+ // Packed size is dynamic, so we don't know what it'll be. Try to have plenty of space.
+ auto struct_buffer_size = sizeof(code_hash_result)*2;
+ char* struct_buffer = (char*)alloca(struct_buffer_size);
+
+ using VersionType = decltype(code_hash_result::struct_version);
+ const VersionType STRUCT_VERSION = 0;
+ 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);
+
+ return full_result->code_hash;
+ }
+
  /**
  * Copy up to length bytes of current action data to the specified location
  *

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);
 }