4

我对 write(2) 函数有一个有趣的问题。PrepareResponseForSetCoordinates 函数会导致写入时出现错误的文件描述符错误。

这是错误行： perror("ERROR writing to socket"); 总输出：写入套接字时出错：文件描述符错误

我确信我已经建立了连接，因为 PrepareResponseForConnectionTest 就像一个魅力。

你能知道错误的原因吗？

当我使用 gcc 作为编译器时，没有问题。之后，由于使用了多个新的 cpp 源，我使用 g++ 作为编译器，并且出现此错误。

问候

在我的代码下面：

#define MAX_PMS_MESSAGE_LEN (4096)
unsigned char baCommBuffer[MAX_PMS_MESSAGE_LEN];
unsigned char PrepareResponseForSetCoordinates(void)
{
    unsigned char baTempBuff[255]={0};
    unsigned short bCnt=0,i=0,bCsum=0,bCnt2=0;
time_t lEpochTime;
time_t lSessionTime;

memset(baTempBuff,0,sizeof(baTempBuff));
memset(baCommBuffer,0,sizeof(baCommBuffer));
bzero(baCommBuffer,MAX_PMS_MESSAGE_LEN);
bzero(baTempBuff,sizeof(baTempBuff));


lEpochTime = time(NULL);
baCommBuffer[bCnt++]    =   START_CHAR;
baCommBuffer[bCnt++]    =   START_CHAR;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
sprintf((char*)baTempBuff,"%ld",(unsigned long)lEpochTime);
memcpy(baCommBuffer+bCnt,baTempBuff,10);

bzero(baTempBuff,sizeof(baTempBuff));
bCnt+=10;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
//  lSessionTime = time(NULL);
if(SPMSMessage.lSessionID)
lSessionTime = SPMSMessage.lSessionID; 
else
lSessionTime=lEpochTime;
sprintf((char*)baTempBuff,"%ld",(unsigned long)lSessionTime);
memcpy(baCommBuffer+bCnt,baTempBuff,10);
bzero(baTempBuff,sizeof(baTempBuff));
bCnt+=10;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   PMC_ID;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   PMS_ID;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'R';
baCommBuffer[bCnt++]    =   'E';
baCommBuffer[bCnt++]    =   'P';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'C';
baCommBuffer[bCnt++]    =   'O';
baCommBuffer[bCnt++]    =   'O';
baCommBuffer[bCnt++]    =   'S';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
if(SPMSMessage.bParam== SET_COOR_CAM1_PARAM)
{
baCommBuffer[bCnt++]    =   '2';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'O';
baCommBuffer[bCnt++]    =   'N';
baCommBuffer[bCnt++]    =   'E';
baCommBuffer[bCnt++]    =   PARAMETER_SEPERATOR;
baCommBuffer[bCnt++]    =   'A';
baCommBuffer[bCnt++]    =   'C';
baCommBuffer[bCnt++]    =   'K';
}
else if(SPMSMessage.bParam== SET_COOR_CAM2_PARAM)
{
baCommBuffer[bCnt++]    =   '2';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'T';
baCommBuffer[bCnt++]    =   'W';
baCommBuffer[bCnt++]    =   'O';
baCommBuffer[bCnt++]    =   PARAMETER_SEPERATOR;
baCommBuffer[bCnt++]    =   'A';
baCommBuffer[bCnt++]    =   'C';
baCommBuffer[bCnt++]    =   'K';    
}
else
{
baCommBuffer[bCnt++]    =   '1';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'N';
baCommBuffer[bCnt++]    =   'A';
baCommBuffer[bCnt++]    =   'C';
baCommBuffer[bCnt++]    =   'K';        
}
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   '*';
memset(baTempBuff,0,sizeof(baTempBuff));
bCsum = CalculateCheckSum(baCommBuffer);
sprintf((char*)baTempBuff,"%.2X",bCsum);
memcpy(baCommBuffer+bCnt,baTempBuff,2);
bzero(baTempBuff,sizeof(baTempBuff));
bCnt+=2;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   END_CHAR;
baCommBuffer[bCnt++]    =   END_CHAR;

#ifdef _DEBUG_DEEP_DETAILED
            if(EDebugDeepDetail<GetDebugLevelOfPMC())
            {
                    printf("WILL BE sent: %s uzunluk:%d\n", baCommBuffer,bCnt);
                    sprintf(caLogStr,"WILL BE sent: %s uzunluk:%d\n", baCommBuffer,bCnt);
                    PrintToLogFile(caLogStr);
                    memset(caLogStr,0,MAX_LOG_STRLEN);
                }
#endif

        if((ETcpConnectionState== ETcpStateConnected) || (ETcpConnectionState== ETcpStateConnectedAndWaitingToWrite) )
        {

            if (write(sockfd,baCommBuffer,bCnt) < 0)
            {
                #ifdef _DEBUG_DETAILED
                if(EDebugDetail<GetDebugLevelOfPMC())
                {
                     perror("ERROR writing to socket"); 
                     PrintToLogFile("ERROR writing to socket");

                 }
                 #endif
             return 0;
            }
                #ifdef _DEBUG_DEEP_DETAILED
                if(EDebugDeepDetail<GetDebugLevelOfPMC())
                {
                    printf("sent: %s uzunluk:%d\n", baCommBuffer,bCnt);
                    sprintf(caLogStr,"sent: %s uzunluk:%d\n", baCommBuffer,bCnt);
                    PrintToLogFile(caLogStr);
                    memset(caLogStr,0,MAX_LOG_STRLEN);
                }
                #endif
        }
        else
        {
                #ifdef _DEBUG_DETAILED
                    if(EDebugDetail<GetDebugLevelOfPMC())
                    {
                    PrintToLogFile("Henüz Bağlantı Yok\n");
                    }
                #endif
                return 0;
        }


return (bCnt);

}

在下面，您可以看到运行时没有错误的代码：

unsigned char PrepareResponseForConnectionTest(void)
{

unsigned char baTempBuff[20]={0};
unsigned char bCnt=0,i=0,bCsum=0;
time_t lEpochTime;
time_t lSessionTime;

memset(baTempBuff,0,sizeof(baTempBuff));
memset(baCommBuffer,0,sizeof(baCommBuffer));
bzero(baCommBuffer,MAX_PMS_MESSAGE_LEN);
bzero(baTempBuff,sizeof(baTempBuff));


lEpochTime = time(NULL);
baCommBuffer[bCnt++]    =   START_CHAR;
baCommBuffer[bCnt++]    =   START_CHAR;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
sprintf((char*)baTempBuff,"%ld",(unsigned long)lEpochTime);
memcpy(baCommBuffer+bCnt,baTempBuff,10);

bzero(baTempBuff,sizeof(baTempBuff));
bCnt+=10;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;

lSessionTime = SPMSMessage.lSessionID; 
sprintf((char*)baTempBuff,"%ld",(unsigned long)lSessionTime);
memcpy(baCommBuffer+bCnt,baTempBuff,10);
bzero(baTempBuff,sizeof(baTempBuff));
bCnt+=10;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   PMC_ID;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   PMS_ID;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'R';
baCommBuffer[bCnt++]    =   'E';
baCommBuffer[bCnt++]    =   'P';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'C';
baCommBuffer[bCnt++]    =   'O';
baCommBuffer[bCnt++]    =   'N';
baCommBuffer[bCnt++]    =   'T';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   '1';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   'A';
baCommBuffer[bCnt++]    =   'C';
baCommBuffer[bCnt++]    =   'K';
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   '*';
memset(baTempBuff,0,sizeof(baTempBuff));
bCsum = CalculateCheckSum(baCommBuffer);
sprintf((char*)baTempBuff,"%.2X",bCsum);
memcpy(baCommBuffer+bCnt,baTempBuff,2);
bzero(baTempBuff,sizeof(baTempBuff));
bCnt+=2;
baCommBuffer[bCnt++]    =   PACKET_SEPERATOR;
baCommBuffer[bCnt++]    =   END_CHAR;
baCommBuffer[bCnt++]    =   END_CHAR;



        if((ETcpConnectionState== ETcpStateConnected) || (ETcpConnectionState== ETcpStateConnectedAndWaitingToWrite) )
        {

            if (write(sockfd,baCommBuffer,bCnt) < 0)
            {
             perror("ERROR writing to socket\n");
             PrintToLogFile("ERROR writing to socket\n");
            }
                #ifdef _DEBUG_DEEP_DETAILED
                if(EDebugDeepDetail<GetDebugLevelOfPMC())
                {
                    printf("sent: %s uzunluk:%d\n", baCommBuffer,bCnt);
                    sprintf(caLogStr,"sent: %s uzunluk:%d\n", baCommBuffer,bCnt);
                    PrintToLogFile(caLogStr);
                    memset(caLogStr,0,MAX_LOG_STRLEN);
                }
                #endif
                return 0;
        }
        else
        {
                #ifdef _DEBUG_DETAILED
                    if(EDebugDetail<GetDebugLevelOfPMC())
                    {
                    PrintToLogFile("There is no connection yet\n");
                    }
                #endif
                //return 0;
        }

        //printf("\n\n");
return (bCnt);
}

这是我的 InitializeConnection 函数和 ConnectToServer 函数：

void InitializeTcpConnection(int argc, char *argv[])
{
   int optval;
   socklen_t optlen = sizeof(optval);
ETcpConnectionState = ETcpStateNotConnected;
    if (argc < 3) 
    {
       fprintf(stderr,"usage: %s hostname_or_ip port\n", argv[0]);
       #ifdef _DEBUG_PROCESS
       if(EDebugProcess<GetDebugLevelOfPMC())
       {
        sprintf(caLogStr,"usage: %s hostname_or_ip port\n", argv[0]);
        PrintToLogFile(caLogStr);
        memset(caLogStr,0,MAX_LOG_STRLEN);
        }
       #endif
       exit(0);
    }
    portno = atoi(argv[2]);
    /* int socket(domain,type,protocol)
     * socket creates an endpoint for communication and returns a descriptor
     * AF_INET: ARPA Internet protocols
     * SOCK_STREAM: sequenced, two way connection based byte streams
     * 
     * return: Socket returns a non-negative descriptor on success.
     * On failure it returns -1 and sets errno to indicate the error
     * */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        #ifdef _DEBUG_PROCESS
        if(EDebugProcess<GetDebugLevelOfPMC())
        {
        perror("ERROR creating socket");
        PrintToLogFile("ERROR creating socket\n");

        }
        #endif
        exit(1);
    }

    /**/


   /* Set the option active */
   optval = 1;
   optlen = sizeof(optval);
   if(setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen) < 0) 
   {
      #ifdef _DEBUG_PROCESS
      if(EDebugProcess<GetDebugLevelOfPMC())
        {
          perror("setsockopt()");
          PrintToLogFile("ERROR creating socket\n");
        }
      #endif
      close(sockfd);
      exit(EXIT_FAILURE);
   }
   #ifdef _DEBUG_PROCESS
   if(EDebugProcess<GetDebugLevelOfPMC())
   {
    printf("SO_KEEPALIVE set on socket\n");
    PrintToLogFile("SO_KEEPALIVE set on socket\n");
    }
      #endif
   /* Check the status again */
   if(getsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &optval, &optlen) < 0) {
       #ifdef _DEBUG_PROCESS
       if(EDebugProcess<GetDebugLevelOfPMC())
       {
          perror("getsockopt()");
          PrintToLogFile("getsockopt()");
      }
      #endif
      close(sockfd);
      exit(EXIT_FAILURE);
   }
   #ifdef _DEBUG_PROCESS
   if(EDebugProcess<GetDebugLevelOfPMC())
   {
   printf("SO_KEEPALIVE is %s\n", (optval ? "ON" : "OFF"));
   }
   #endif

   #ifdef _DEBUG_PROCESS

    if(EDebugProcess<GetDebugLevelOfPMC())
    {
    PrintToLogFile("Setting socket for reusability\n");
    }
   #endif

   if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(int)) == -1) 
   {
       #ifdef _DEBUG_PROCESS
       if(EDebugProcess<GetDebugLevelOfPMC())
       {
                perror("setsockopt");
                PrintToLogFile("Setting socket option error\n");
       }
       #endif
                exit(1);
   }

   /*********/

    //get the address info by either host name or IP address
    SetTcpServerIpAddress(argv[1]);
    server = gethostbyname(argv[1]);
    if (server == NULL) 
    {
        #ifdef _DEBUG_PROCESS
        if(EDebugProcess<GetDebugLevelOfPMC())
        {
        PrintToLogFile("ERROR, no such host\n");
        }
        #endif
        exit(1);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
    //serv_addr.sin_port: unsigned short 
    //htons converts the unsigned short hostshort from host byte order to network byte order
    serv_addr.sin_port = htons(portno);


    ETcpConnectionState = ETcpStateWaitingForConnection;

}

int ConnectToServer(void)
{
                    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)  
                    {
                        #ifdef _DEBUG_DETAILED
                        if(EDebugDetail<GetDebugLevelOfPMC())
                        {
                        PrintToLogFile("ERROR connecting");
                        }
                        #endif
                        return 1; // connection error
                        //exit(1);
                    }
                    else
                    {
                        #ifdef _DEBUG_DETAILED
                        if(EDebugDetail<GetDebugLevelOfPMC())
                        {
                        PrintToLogFile("connection established\n");
                        }
                        #endif
                    #ifndef PMS_COMM_POLL_MODE
                        #ifdef _DEBUG_DETAILED
                        if(EDebugDetail<GetDebugLevelOfPMC())
                        {
                        PrintToLogFile("State is non poll mode\n");
                        }
                        #endif
                    ETcpConnectionState = ETcpStateConnected;
                    #endif
                    #ifdef PMS_COMM_POLL_MODE
                        #ifdef _DEBUG_DETAILED
                        if(EDebugDetail<GetDebugLevelOfPMC())
                        {
                        PrintToLogFile("State is poll mode\n"); 
                        }
                        #endif
                    ETcpConnectionState = ETcpStateConnectedAndWaitingToRead;
                    #endif

                    SendRequestToGetImageUploadInfo();
                    }
return 0;   
}
4

3 回答 3

18

一般来说，当遇到“Bad File Descriptor”时，说明你传入API的socket文件描述符无效，可能有多种原因：

  1. fd 已经在某处关闭。
  2. fd有错误的值，与socket() api获取的值不一致
于 2012-07-01T01:39:10.070 回答
6

我也有这个错误，我的问题出在代码的某些部分我没有关闭文件描述符，而在其他部分，我试图打开那个文件！！close(fd)处理完文件后使用系统调用。

于 2015-10-12T18:52:40.447 回答
5

The value you have passed as the file descriptor is not valid. It is either negative or does not represent a currently open file or socket.

So you have either closed the socket before calling write() or you have corrupted the value of 'sockfd' somewhere in your code.

It would be useful to trace all calls to close(), and the value of 'sockfd' prior to the write() calls.

Your technique of only printing error messages in debug mode seems to me complete madness, and in any case calling another function between a system call and perror() is invalid, as it may disturb the value of errno. Indeed it may have done so in this case, and the real underlying error may be different.

于 2012-07-01T00:53:30.743 回答