带有 Linux 套接字的坏文件描述符 write() 坏文件描述符 C
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Bad File Descriptor with Linux Socket write() Bad File Descriptor C
提问by user1336117
I have an interesting problem with write(2) function. PrepareResponseForSetCoordinates function causes bad file descriptor error on write.
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。
Here is the line of error: perror("ERROR writing to socket"); total output: ERROR writing to socket: Bad file descriptor
这是错误行： perror("ERROR writing to socket"); 总输出：错误写入套接字：错误的文件描述符
I am sure that I have established the connection because PrepareResponseForConnectionTest works like a charm.
我确信我已经建立了连接，因为 PrepareResponseForConnectionTest 就像一个魅力。
Can you have any idea about the reason of the error?
你能知道错误的原因吗？
When I use gcc as compiler there was no problem. After that because of using multiple new cpp sources I am using g++ as compiler and I have this error.
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。
Regards
问候
Here below my code:
下面是我的代码：
#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 Ba?lant? Yok\n");
}
#endif
return 0;
}
return (bCnt);
}
}
Here below you can see the code which run without error:
下面你可以看到运行没有错误的代码：
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);
}
Here is my InitializeConnection function and ConnectToServer function:
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;
}
采纳答案by ciphor
In general, when "Bad File Descriptor" is encountered, it means that the socket file descriptor you passed into the API is not valid, which has multiple possible reasons:
一般情况下，当遇到“Bad File Descriptor”时，说明你传入API的socket文件描述符无效，这有多种可能的原因：
- The fd is already closed somewhere.
- The fd has a wrong value, which is inconsistent with the value obtained from socket() api
- fd 已经在某处关闭了。
- fd值错误，与socket() api获取的值不一致
回答by user207421
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.
您作为文件描述符传递的值无效。它要么是负数，要么不代表当前打开的文件或套接字。
So you have either closed the socket before calling write()or you have corrupted the value of 'sockfd' somewhere in your code.
因此，您要么在调用之前关闭了套接字，要么write()在代码中的某处损坏了 'sockfd' 的值。
It would be useful to trace all calls to close(), and the value of 'sockfd' prior to the write()calls.
close()在write()调用之前跟踪对 的所有调用以及 'sockfd' 的值会很有用。
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.
你在调试模式下只打印错误消息的技术在我看来完全是疯了，无论如何在系统调用之间调用另一个函数perror()是无效的，因为它可能会干扰errno. 事实上，在这种情况下它可能已经这样做了，而真正的潜在错误可能会有所不同。
