/**

 *

 * Copyrights

 *

 * Portions created or assigned to Cisco Systems, Inc. are

 * Copyright (c) 2014-2016 Cisco Systems, Inc.  All Rights Reserved.

 */

#include <openssl/err.h>

#include "cjose/error.h"

// thread-local storage specifier: MSVC spells it __declspec(thread),

// GCC/Clang use __thread, C11 has _Thread_local

#if defined(_MSC_VER)

#define CJOSE_THREAD_LOCAL __declspec(thread)

#elif defined(__GNUC__) || defined(__clang__)

#define CJOSE_THREAD_LOCAL __thread

#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L

#define CJOSE_THREAD_LOCAL _Thread_local

#else

#define CJOSE_THREAD_LOCAL

#endif

////////////////////////////////////////////////////////////////////////////////

static const char *_ERR_MSG_TABLE[] = { "no error", "invalid argument", "invalid state", "out of memory", "crypto error" };

////////////////////////////////////////////////////////////////////////////////

const char *cjose_err_message(cjose_errcode code)

{

    const char *retval = NULL;

    if (CJOSE_ERR_CRYPTO == code)

    {

        // for crypto errors, return the most recent openssl error as message;

        // render it into a thread-local buffer since ERR_error_string with a

        // NULL buffer returns a static buffer shared across threads

        static CJOSE_THREAD_LOCAL char buf[256];

        unsigned long err = ERR_get_error();

        while (0 != err)

        {

            ERR_error_string_n(err, buf, sizeof(buf));

            retval = buf;

            err = ERR_get_error();

        }

    }

    if (NULL == retval)

    {

        // the code is caller-supplied; don't index the table out of bounds

        if ((size_t)code >= sizeof(_ERR_MSG_TABLE) / sizeof(_ERR_MSG_TABLE[0]))

        {

            return "unknown error";

        }

        retval = _ERR_MSG_TABLE[code];

    }

    return retval;

}