我正在研究终端输出中有关接收空字符“\0”的一些意外行为。我发送了一个字符串,我期望它包含 2 个 \0,但这并未显示在 PuTTY 上。
根据这个问题这意味着 PuTTY 在正常情况下不会发送空值。然而,这个问题已经存在近 10 年了,我认为 PuTTY 在此期间已经收到更新。
我已经调查过PuTTY 用户手册并且主要找到了有关 PuTTY 面板的文档以及大量有关错误消息和连接性的文档。第三.3 章讨论了“改变你的字符集配置”,但主要涉及非拉丁字母,并且链接到第四章 第 10 节,即翻译面板。
我的问题很简单,当 PuTTY 需要接收 \0 字符时,它通常会做什么?它没有接收到吗?它是否接收到字符但未显示在终端中?
如果需要更多信息,请告诉我。
用于将数据发送到PuTTY的代码是C语言的,在STM32板上:
static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
{
/* USER CODE BEGIN 6 */
USBD_CDC_SetRxBuffer(&hUsbDeviceFS, &Buf[0]);
USBD_CDC_ReceivePacket(&hUsbDeviceFS);
memset (buffer, '\0', 64); // clear the buffer
uint8_t len = (uint8_t)*Len; //Converts Len as uint32_t to len as uint8_t
memcpy(buffer, Buf, len); // copy the data to the buffer
memset(Buf, '\0', len); // clear the Buf also
//Code used to send message back
/*In the full version, there will be another function outside of this file.
* The buffer will be processed and a proper message will be sent.
* Check that other file to see how it gets processed when we eventually implement it.
*/
uint8_t transmit_message[64] = "TOWST_FIRMV_REEEEEEE_27\r\n"; //Do we have \r\n?
//CDC_Transmit_FS(transmit_message, sizeof(transmit_message));
//HAL_GPIO_TogglePin(GPIOF, GPIO_PIN_10);
//message_Received(buffer, len);
process_Message(buffer, len);
return (USBD_OK);
/* USER CODE END 6 */
}
void process_Message(uint8_t* message, uint16_t Len){
HAL_GPIO_TogglePin(GPIOF, GPIO_PIN_10);
uint8_t* inputCmd[5];
uint8_t* inputMessage[8];
uint8_t outputCmd[5];
uint8_t outputData[8];
// strcpy((char*) inputCmd, (const char*)message + COMMAND_CHAR);
// strcpy((char*) inputMessage, (const char*)message + DATA_CHAR);
if (strcmp(inputCmd, "FIRMV") == 0){
memcpy(outputCmd, "FIRMV", COMMAND_LENGTH);
memcpy(outputData, "01050A00", DATA_LENGTH);
}
else{
memcpy(outputCmd, "REEEE", COMMAND_LENGTH);
memcpy(outputData, "99999999", DATA_LENGTH);
}
// message_Received(message, Len);
send_Message(outputCmd, outputData);
}
void send_Message(uint8_t* cmd, uint8_t* data){
uint8_t outputMessage[25] = "TOWST_"; //Size of array is for future uses.
strncpy((char*) outputMessage + 8, "FIRMV", 5);
CDC_Transmit_FS(outputMessage, sizeof(outputMessage));
}
//Expected output: 'TOWST_\0\0FIRMV' based on this post, which per my understanding suggests that strncpy will fill in unfilled memory with null chars. https://aticleworld.com/how-to-use-strncpy-and-how-to-write-your-own-strncpy