技術標籤：資料加密與安全專題mbedtlshello

上一篇中提及mbedtls工具安裝後，可以使用hello命令進行驗證是否已安裝成功，那麼hello命令來自哪裡，如何增加一條自定義的命令

原始碼路徑：mbedtls/programs/hash

目錄結構：

可以看到原始碼hello.c原始檔，檢視原始碼：

/*
 *  Classic "Hello, world" demonstration program
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#include <stdio.h>
#define mbedtls_printf       printf
#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif

#if defined(MBEDTLS_MD5_C)
#include "mbedtls/md5.h"
#endif

#if !defined(MBEDTLS_MD5_C)
int main( void )
{
    mbedtls_printf("MBEDTLS_MD5_C not defined.\n");
    return( 0 );
}
#else
int main( void )
{
    int i, ret;
    unsigned char digest[16];
    char str[] = "Hello, world!";

    mbedtls_printf( "\n  MD5('%s') = ", str );

    if( ( ret = mbedtls_md5_ret( (unsigned char *) str, 13, digest ) ) != 0 )
        return( MBEDTLS_EXIT_FAILURE );

    for( i = 0; i < 16; i++ )
        mbedtls_printf( "%02x", digest[i] );

    mbedtls_printf( "\n\n" );

#if defined(_WIN32)
    mbedtls_printf( "  Press Enter to exit this program.\n" );
    fflush( stdout ); getchar();
#endif

    return( MBEDTLS_EXIT_SUCCESS );
}
#endif /* MBEDTLS_MD5_C */
 

這麼看來Ubuntu終端中的hello命令，就是由hello.c原始檔生成，並拷貝到/usr/local/bin/資料夾中，於是進一步驗證：

再看下CMakeLists.txt檔案內容來驗證：

add_executable(hello hello.c)
target_link_libraries(hello mbedtls)

add_executable(generic_sum generic_sum.c)
target_link_libraries(generic_sum mbedtls)

install(TARGETS hello generic_sum
        DESTINATION "bin"
        PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
 

通過以上分析，得出hello命令的由來，按照hello命令的編寫方法，可以嘗試增加自定義的指令了，動起手來吧！