void err_clear_last_constant_time(int clear)
{
    ERR_STATE *es;
    int top;
    es = ERR_get_state();
    if (es == NULL)
        return;
    top = es->top;
    es->err_flags[top] &= ~(0 - clear);
    es->err_buffer[top] &= ~(0UL - clear);
    es->err_file[top] = (const char *)((UINTPTR_T)es->err_file[top] &
                                       ~((UINTPTR_T)0 - clear));
    es->err_line[top] |= 0 - clear;
    es->top = (top + ERR_NUM_ERRORS - clear) % ERR_NUM_ERRORS;
}
['int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,\n                                      const unsigned char *from, int flen,\n                                      int num, const unsigned char *param,\n                                      int plen, const EVP_MD *md,\n                                      const EVP_MD *mgf1md)\n{\n    int i, dblen = 0, mlen = -1, one_index = 0, msg_index;\n    unsigned int good = 0, found_one_byte, mask;\n    const unsigned char *maskedseed, *maskeddb;\n    unsigned char *db = NULL, *em = NULL, seed[EVP_MAX_MD_SIZE],\n        phash[EVP_MAX_MD_SIZE];\n    int mdlen;\n    if (md == NULL)\n        md = EVP_sha1();\n    if (mgf1md == NULL)\n        mgf1md = md;\n    mdlen = EVP_MD_size(md);\n    if (tlen <= 0 || flen <= 0)\n        return -1;\n    if (num < flen || num < 2 * mdlen + 2) {\n        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,\n               RSA_R_OAEP_DECODING_ERROR);\n        return -1;\n    }\n    dblen = num - mdlen - 1;\n    db = OPENSSL_malloc(dblen);\n    if (db == NULL) {\n        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);\n        goto cleanup;\n    }\n    em = OPENSSL_malloc(num);\n    if (em == NULL) {\n        RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,\n               ERR_R_MALLOC_FAILURE);\n        goto cleanup;\n    }\n    for (from += flen, em += num, i = 0; i < num; i++) {\n        mask = ~constant_time_is_zero(flen);\n        flen -= 1 & mask;\n        from -= 1 & mask;\n        *--em = *from & mask;\n    }\n    good = constant_time_is_zero(em[0]);\n    maskedseed = em + 1;\n    maskeddb = em + 1 + mdlen;\n    if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))\n        goto cleanup;\n    for (i = 0; i < mdlen; i++)\n        seed[i] ^= maskedseed[i];\n    if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md))\n        goto cleanup;\n    for (i = 0; i < dblen; i++)\n        db[i] ^= maskeddb[i];\n    if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL))\n        goto cleanup;\n    good &= constant_time_is_zero(CRYPTO_memcmp(db, phash, mdlen));\n    found_one_byte = 0;\n    for (i = mdlen; i < dblen; i++) {\n        unsigned int equals1 = constant_time_eq(db[i], 1);\n        unsigned int equals0 = constant_time_is_zero(db[i]);\n        one_index = constant_time_select_int(~found_one_byte & equals1,\n                                             i, one_index);\n        found_one_byte |= equals1;\n        good &= (found_one_byte | equals0);\n    }\n    good &= found_one_byte;\n    msg_index = one_index + 1;\n    mlen = dblen - msg_index;\n    good &= constant_time_ge(tlen, mlen);\n    tlen = constant_time_select_int(constant_time_lt(dblen - mdlen - 1, tlen),\n                                    dblen - mdlen - 1, tlen);\n    msg_index = constant_time_select_int(good, msg_index, dblen - tlen);\n    mlen = dblen - msg_index;\n    for (mask = good, i = 0; i < tlen; i++) {\n        unsigned int equals = constant_time_eq(msg_index, dblen);\n        msg_index -= tlen & equals;\n        mask &= ~equals;\n        to[i] = constant_time_select_8(mask, db[msg_index++], to[i]);\n    }\n    RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1,\n           RSA_R_OAEP_DECODING_ERROR);\n    err_clear_last_constant_time(1 & good);\n cleanup:\n    OPENSSL_cleanse(seed, sizeof(seed));\n    OPENSSL_clear_free(db, dblen);\n    OPENSSL_clear_free(em, num);\n    return constant_time_select_int(good, mlen, -1);\n}', 'void err_clear_last_constant_time(int clear)\n{\n    ERR_STATE *es;\n    int top;\n    es = ERR_get_state();\n    if (es == NULL)\n        return;\n    top = es->top;\n    es->err_flags[top] &= ~(0 - clear);\n    es->err_buffer[top] &= ~(0UL - clear);\n    es->err_file[top] = (const char *)((UINTPTR_T)es->err_file[top] &\n                                       ~((UINTPTR_T)0 - clear));\n    es->err_line[top] |= 0 - clear;\n    es->top = (top + ERR_NUM_ERRORS - clear) % ERR_NUM_ERRORS;\n}']