// EVMC: Ethereum Client-VM Connector API.

// Copyright 2018 The EVMC Authors.

// Licensed under the Apache License, Version 2.0.

#include <evmc/loader.h>

#include <evmc/evmc.h>

#include <evmc/helpers.h>

#include <stdarg.h>

#include <stdint.h>

#include <stdio.h>

#include <string.h>

#if defined(EVMC_LOADER_MOCK)

#include "../../test/unittests/loader_mock.h"

#elif defined(_WIN32)

#include <Windows.h>

#define DLL_HANDLE HMODULE

#define DLL_OPEN(filename) LoadLibrary(filename)

#define DLL_CLOSE(handle) FreeLibrary(handle)

#define DLL_GET_CREATE_FN(handle, name) (evmc_create_fn)(uintptr_t) GetProcAddress(handle, name)

#define DLL_GET_ERROR_MSG() NULL

#else

#include <dlfcn.h>

#define DLL_HANDLE void*

#define DLL_OPEN(filename) dlopen(filename, RTLD_LAZY)

#define DLL_CLOSE(handle) dlclose(handle)

// NOLINTNEXTLINE(performance-no-int-to-ptr)

#define DLL_GET_CREATE_FN(handle, name) (evmc_create_fn)(uintptr_t) dlsym(handle, name)

#define DLL_GET_ERROR_MSG() dlerror()

#endif

#ifdef __has_attribute

#if __has_attribute(format)

#define ATTR_FORMAT(archetype, string_index, first_to_check) \

    __attribute__((format(archetype, string_index, first_to_check)))

#endif

#endif

#ifndef ATTR_FORMAT

#define ATTR_FORMAT(...)

#endif

/*

 * Limited variant of strcpy_s().

 */

#if !defined(EVMC_LOADER_MOCK)

static

#endif

    int

    strcpy_sx(char* dest, size_t destsz, const char* src)

{

    size_t len = strlen(src);

    if (len >= destsz)

    {

        // The input src will not fit into the dest buffer.

        // Set the first byte of the dest to null to make it effectively empty string

        // and return error.

        dest[0] = 0;

        return 1;

    }

    // NOLINTNEXTLINE(clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling)

    memcpy(dest, src, len);

    dest[len] = 0;

    return 0;

}

enum

{

    PATH_MAX_LENGTH = 4096,

    LAST_ERROR_MSG_BUFFER_SIZE = 511

};

static const char* last_error_msg = NULL;

// Buffer for formatted error messages.

// It has one null byte extra to avoid buffer read overflow during concurrent access.

static char last_error_msg_buffer[LAST_ERROR_MSG_BUFFER_SIZE + 1];

ATTR_FORMAT(printf, 2, 3)

static enum evmc_loader_error_code set_error(enum evmc_loader_error_code error_code,

                                             const char* format,

                                             ...)

{

    va_list args;

    va_start(args, format);

    // NOLINTNEXTLINE(clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling)

    if (vsnprintf(last_error_msg_buffer, LAST_ERROR_MSG_BUFFER_SIZE, format, args) <

        LAST_ERROR_MSG_BUFFER_SIZE)

        last_error_msg = last_error_msg_buffer;

    va_end(args);

    return error_code;

}

evmc_create_fn evmc_load(const char* filename, enum evmc_loader_error_code* error_code)

{

    last_error_msg = NULL;  // Reset last error.

    enum evmc_loader_error_code ec = EVMC_LOADER_SUCCESS;

    evmc_create_fn create_fn = NULL;

    if (!filename)

    {

        ec = set_error(EVMC_LOADER_INVALID_ARGUMENT, "invalid argument: file name cannot be null");

        goto exit;

    }

    const size_t length = strlen(filename);

    if (length == 0)

    {

        ec = set_error(EVMC_LOADER_INVALID_ARGUMENT, "invalid argument: file name cannot be empty");

        goto exit;

    }

    else if (length > PATH_MAX_LENGTH)

    {

        ec = set_error(EVMC_LOADER_INVALID_ARGUMENT,

                       "invalid argument: file name is too long (%d, maximum allowed length is %d)",

                       (int)length, PATH_MAX_LENGTH);

        goto exit;

    }

    DLL_HANDLE handle = DLL_OPEN(filename);

    if (!handle)

    {

        // Get error message if available.

        last_error_msg = DLL_GET_ERROR_MSG();

        if (last_error_msg)

            ec = EVMC_LOADER_CANNOT_OPEN;

        else

            ec = set_error(EVMC_LOADER_CANNOT_OPEN, "cannot open %s", filename);

        goto exit;

    }

    // Create name buffer with the prefix.

    const char prefix[] = "evmc_create_";

    const size_t prefix_length = strlen(prefix);

    char prefixed_name[sizeof(prefix) + PATH_MAX_LENGTH];

    strcpy_sx(prefixed_name, sizeof(prefixed_name), prefix);

    // Find filename in the path.

    const char* sep_pos = strrchr(filename, '/');

#ifdef _WIN32

    // On Windows check also Windows classic path separator.

    const char* sep_pos_windows = strrchr(filename, '\\');

    sep_pos = sep_pos_windows > sep_pos ? sep_pos_windows : sep_pos;

#endif

    const char* name_pos = sep_pos ? sep_pos + 1 : filename;

    // Skip "lib" prefix if present.

    const char lib_prefix[] = "lib";

    const size_t lib_prefix_length = strlen(lib_prefix);

    if (strncmp(name_pos, lib_prefix, lib_prefix_length) == 0)

        name_pos += lib_prefix_length;

    char* base_name = prefixed_name + prefix_length;

    strcpy_sx(base_name, PATH_MAX_LENGTH, name_pos);

    // Trim all file extensions.

    char* ext_pos = strchr(prefixed_name, '.');

    if (ext_pos)

        *ext_pos = 0;

    // Replace all "-" with "_".

    char* dash_pos = base_name;

    while ((dash_pos = strchr(dash_pos, '-')) != NULL)

        *dash_pos++ = '_';

    // Search for the built function name.

    create_fn = DLL_GET_CREATE_FN(handle, prefixed_name);

    if (!create_fn)

        create_fn = DLL_GET_CREATE_FN(handle, "evmc_create");

    if (!create_fn)

    {

        DLL_CLOSE(handle);

        ec = set_error(EVMC_LOADER_SYMBOL_NOT_FOUND, "EVMC create function not found in %s",

                       filename);

    }

exit:

    if (error_code)

        *error_code = ec;

    return create_fn;

}

const char* evmc_last_error_msg(void)

{

    const char* m = last_error_msg;

    last_error_msg = NULL;

    return m;

}

struct evmc_vm* evmc_load_and_create(const char* filename, enum evmc_loader_error_code* error_code)

{

    // First load the DLL. This also resets the last_error_msg;

    evmc_create_fn create_fn = evmc_load(filename, error_code);

    if (!create_fn)

        return NULL;

    enum evmc_loader_error_code ec = EVMC_LOADER_SUCCESS;

    struct evmc_vm* vm = create_fn();

    if (!vm)

    {

        ec = set_error(EVMC_LOADER_VM_CREATION_FAILURE, "creating EVMC VM of %s has failed",

                       filename);

        goto exit;

    }

    if (!evmc_is_abi_compatible(vm))

    {

        ec = set_error(EVMC_LOADER_ABI_VERSION_MISMATCH,

                       "EVMC ABI version %d of %s mismatches the expected version %d",

                       vm->abi_version, filename, EVMC_ABI_VERSION);

        evmc_destroy(vm);

        vm = NULL;

        goto exit;

    }

exit:

    if (error_code)

        *error_code = ec;

    return vm;

}

/// Gets the token delimited by @p delim character of the string pointed by the @p str_ptr.

/// If the delimiter is not found, the whole string is returned.

/// The @p str_ptr is also slided after the delimiter or to the string end

/// if the delimiter is not found (in this case the @p str_ptr points to an empty string).

static char* get_token(char** str_ptr, char delim)

{

    char* str = *str_ptr;

    char* delim_pos = strchr(str, delim);

    if (delim_pos)

    {

        // If the delimiter is found, null it to get null-terminated prefix

        // and slide the str_ptr after the delimiter.

        *delim_pos = '\0';

        *str_ptr = delim_pos + 1;

    }

    else

    {

        // Otherwise, slide the str_ptr to the end and return the whole string as the prefix.

        *str_ptr += strlen(str);

    }

    return str;

}

struct evmc_vm* evmc_load_and_configure(const char* config, enum evmc_loader_error_code* error_code)

{

    enum evmc_loader_error_code ec = EVMC_LOADER_SUCCESS;

    struct evmc_vm* vm = NULL;

    char config_copy_buffer[PATH_MAX_LENGTH];

    if (strcpy_sx(config_copy_buffer, sizeof(config_copy_buffer), config) != 0)

    {

        ec = set_error(EVMC_LOADER_INVALID_ARGUMENT,

                       "invalid argument: configuration is too long (maximum allowed length is %d)",

                       (int)sizeof(config_copy_buffer));

        goto exit;

    }

    char* options = config_copy_buffer;

    const char* path = get_token(&options, ',');

    vm = evmc_load_and_create(path, error_code);

    if (!vm)

        return NULL;

    while (strlen(options) != 0)

    {

        if (vm->set_option == NULL)

        {

            ec = set_error(EVMC_LOADER_INVALID_OPTION_NAME, "%s (%s) does not support any options",

                           vm->name, path);

            goto exit;

        }

        char* option = get_token(&options, ',');

        // Slit option into name and value by taking the name token.

        // The option variable will have the value, can be empty.

        const char* name = get_token(&option, '=');

        enum evmc_set_option_result r = vm->set_option(vm, name, option);

        switch (r)

        {

        case EVMC_SET_OPTION_SUCCESS:

            break;

        case EVMC_SET_OPTION_INVALID_NAME:

            ec = set_error(EVMC_LOADER_INVALID_OPTION_NAME, "%s (%s): unknown option '%s'",

                           vm->name, path, name);

            goto exit;

        case EVMC_SET_OPTION_INVALID_VALUE:

            ec = set_error(EVMC_LOADER_INVALID_OPTION_VALUE,

                           "%s (%s): unsupported value '%s' for option '%s'", vm->name, path,

                           option, name);

            goto exit;

        default:

            ec = set_error(EVMC_LOADER_INVALID_OPTION_VALUE,

                           "%s (%s): unknown error when setting value '%s' for option '%s'",

                           vm->name, path, option, name);

            goto exit;

        }

    }

exit:

    if (error_code)

        *error_code = ec;

    if (ec == EVMC_LOADER_SUCCESS)

        return vm;

    if (vm)

        evmc_destroy(vm);

    return NULL;

}