Add evmc and host interface implementation. Modify fuzzer harness to make use of evmc host/vm.

test/evmc/loader.h

@@ -0,0 +1,133 @@
+/* EVMC: Ethereum Client-VM Connector API.
+ * Copyright 2018-2019 The EVMC Authors.
+ * Licensed under the Apache License, Version 2.0.
+ */
+
+/**
+ * EVMC Loader Library
+ *
+ * The EVMC Loader Library supports loading VMs implemented as Dynamically Loaded Libraries
+ * (DLLs, shared objects).
+ *
+ * @defgroup loader EVMC Loader
+ * @{
+ */
+#pragma once
+
+#if __cplusplus
+extern "C" {
+#endif
+
+/** The function pointer type for EVMC create functions. */
+typedef struct evmc_instance* (*evmc_create_fn)(void);
+
+/** Error codes for the EVMC loader. */
+enum evmc_loader_error_code
+{
+    /** The loader succeeded. */
+    EVMC_LOADER_SUCCESS = 0,
+
+    /** The loader cannot open the given file name. */
+    EVMC_LOADER_CANNOT_OPEN = 1,
+
+    /** The VM create function not found. */
+    EVMC_LOADER_SYMBOL_NOT_FOUND = 2,
+
+    /** The invalid argument value provided. */
+    EVMC_LOADER_INVALID_ARGUMENT = 3,
+
+    /** The creation of a VM instance has failed. */
+    EVMC_LOADER_INSTANCE_CREATION_FAILURE = 4,
+
+    /** The ABI version of the VM instance has mismatched. */
+    EVMC_LOADER_ABI_VERSION_MISMATCH = 5
+};
+
+/**
+ * Dynamically loads the EVMC module with a VM implementation.
+ *
+ * This function tries to open a dynamically loaded library (DLL) at the given `filename`.
+ * On UNIX-like systems dlopen() function is used. On Windows LoadLibrary() function is used.
+ *
+ * If the file does not exist or is not a valid shared library the ::EVMC_LOADER_CANNOT_OPEN error
+ * code is signaled and NULL is returned.
+ *
+ * After the DLL is successfully loaded the function tries to find the EVM create function in the
+ * library. The `filename` is used to guess the EVM name and the name of the create function.
+ * The create function name is constructed by the following rules. Consider example path:
+ * "/ethereum/libexample-interpreter.so".
+ * - the filename is taken from the path:
+ *   "libexample-interpreter.so",
+ * - the "lib" prefix and file extension are stripped from the name:
+ *   "example-interpreter"
+ * - all "-" are replaced with "_" to construct _base name_:
+ *   "example_interpreter",
+ * - the function name "evmc_create_" + _base name_ is searched in the library:
+ *   "evmc_create_example_interpreter",
+ * - if function not found, the _base name_ is shorten by skipping the first word separated by "_":
+ *   "interpreter",
+ * - then, the function of the shorter name "evmc_create_" + _base name_ is searched in the library:
+ *   "evmc_create_interpreter",
+ * - the name shortening continues until a function is found or the name cannot be shorten more,
+ * - lastly, when no function found, the function name "evmc_create" is searched in the library.
+ *
+ * If the create function is found in the library, the pointer to the function is returned.
+ * Otherwise, the ::EVMC_LOADER_SYMBOL_NOT_FOUND error code is signaled and NULL is returned.
+ *
+ * It is safe to call this function with the same filename argument multiple times
+ * (the DLL is not going to be loaded multiple times).
+ *
+ * @param filename    The null terminated path (absolute or relative) to an EVMC module
+ *                    (dynamically loaded library) containing the VM implementation.
+ *                    If the value is NULL, an empty C-string or longer than the path maximum length
+ *                    the ::EVMC_LOADER_INVALID_ARGUMENT is signaled.
+ * @param error_code  The pointer to the error code. If not NULL the value is set to
+ *                    ::EVMC_LOADER_SUCCESS on success or any other error code as described above.
+ * @return            The pointer to the EVM create function or NULL in case of error.
+ */
+evmc_create_fn evmc_load(const char* filename, enum evmc_loader_error_code* error_code);
+
+/**
+ * Dynamically loads the EVMC module and creates the VM instance.
+ *
+ * This is a macro for creating the VM instance with the function returned from evmc_load().
+ * The function signals the same errors as evmc_load() and additionally:
+ * - ::EVMC_LOADER_INSTANCE_CREATION_FAILURE when the create function returns NULL,
+ * - ::EVMC_LOADER_ABI_VERSION_MISMATCH when the created VM instance has ABI version different
+ *   from the ABI version of this library (::EVMC_ABI_VERSION).
+ *
+ * It is safe to call this function with the same filename argument multiple times:
+ * the DLL is not going to be loaded multiple times, but the function will return new VM instance
+ * each time.
+ *
+ * @param filename    The null terminated path (absolute or relative) to an EVMC module
+ *                    (dynamically loaded library) containing the VM implementation.
+ *                    If the value is NULL, an empty C-string or longer than the path maximum length
+ *                    the ::EVMC_LOADER_INVALID_ARGUMENT is signaled.
+ * @param error_code  The pointer to the error code. If not NULL the value is set to
+ *                    ::EVMC_LOADER_SUCCESS on success or any other error code as described above.
+ * @return            The pointer to the created VM or NULL in case of error.
+ */
+struct evmc_instance* evmc_load_and_create(const char* filename,
+                                           enum evmc_loader_error_code* error_code);
+
+/**
+ * Returns the human-readable message describing the most recent error
+ * that occurred in EVMC loading since the last call to this function.
+ *
+ * In case any loading function returned ::EVMC_LOADER_SUCCESS this function always returns NULL.
+ * In case of error code other than success returned, this function MAY return the error message.
+ * Calling this function "consumes" the error message and the function will return NULL
+ * from subsequent invocations.
+ * This function is not thread-safe.
+ *
+ * @return Error message or NULL if no additional information is available.
+ *         The returned pointer MUST NOT be freed by the caller.
+ */
+const char* evmc_last_error_msg();
+
+#if __cplusplus
+}
+#endif
+
+/** @} */