接收文件时出错
我有这个代码：
while (1) {
char buffer[4096];
memset(buffer,0,4096);
int bytes_read = recv(client_fd, buffer, sizeof(buffer),0);
if (bytes_read == 0)
break;
if (bytes_read < 0) {
std::cout<< "Error "<<endl;
}
void *p = buffer;
int dest;
dest=open("/root/hello.txt",O_WRONLY);
while (bytes_read > 0) {
int bytes_written = send(dest, buffer, bytes_read,0);
if (bytes_written <= 0) {
std::cout<< "Error2 "<<endl;
}
bytes_read -= bytes_written;
p += bytes_written;
}
}
我正确收到文件。 程序进入循环，其中 cout 为“Error2”，因此发送返回 -1。 问题是将文件写入新的文件描述符，在本例中为名为 dest 的变量。 我该如何解决这个问题？
I have this code:
while (1) {
char buffer[4096];
memset(buffer,0,4096);
int bytes_read = recv(client_fd, buffer, sizeof(buffer),0);
if (bytes_read == 0)
break;
if (bytes_read < 0) {
std::cout<< "Error "<<endl;
}
void *p = buffer;
int dest;
dest=open("/root/hello.txt",O_WRONLY);
while (bytes_read > 0) {
int bytes_written = send(dest, buffer, bytes_read,0);
if (bytes_written <= 0) {
std::cout<< "Error2 "<<endl;
}
bytes_read -= bytes_written;
p += bytes_written;
}
}
I receive the file correctly.
The program goes in loop where the cout is "Error2", so the send returns -1.
The problem is to write the file in a new file descriptor, in this case the variable called dest.
How can I solve this problem?
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根据
send 的手册页(2)，只能写入套接字，不能写入普通文件；如果您检查了errno（使用例如perror），您会看到它被设置为ENOTSOCK。您应该始终看到正在设置的错误，否则调试只是在黑暗中进行。另外，由于这是 C++，我真的认为您应该使用 C++ 风格的 I/O（
std::ofstream等）来写入常规文件。According to the manual-page for
send(2), it can only write to a socket, not to a regular file; if you had checkederrno(using e.g.perror), you would have seen that it gets set toENOTSOCK. You should always see what error is being set, otherwise debugging is just shooting in the dark.Also, since this is C++, I really think you should use C++-style I/O (
std::ofstreamand so on) to write to a regular file.检查返回值
It应该是一个正整数；其他一切都表明有错误。我的猜测是该文件由于某种原因无法打开。
Check the return value of
It should be a positive integer; everything else indicates an error. My guess is that the file can't be opened for whatever reason.