ERROR on accept: Bad file descriptor - c++

Question

EDIT: Minimal, Complete, and Verifiable example is in comment lower and the code actually works, problem was in different area. Sorry for bad posting, I cannot delete it now.
I know, that there are some pages about this already, but I really tried everything and nothing works. Im having this error all the time and my code looks like this:
int server_socket, new_socket;
struct sockaddr_in server;
bzero((char *) &server, sizeof(server));
server_socket = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
if(server_socket < 0) error("ERROR opening socket");
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl(INADDR_ANY);
server.sin_port = htons(port_number);
if(bind(server_socket, (struct sockaddr *) &server, sizeof(struct sockaddr_in)) < 0) error("ERROR on binding");
if(listen(server_socket, 5) < 0) error("Failed to listen for connections.");
while(1)
{
struct sockaddr_in client;
unsigned int client_len = sizeof(struct sockaddr_in);
bzero((char *) &client, client_len);
if((new_socket = accept(server_socket, (struct sockaddr *) &client, &client_len)) < 0)
{
if(errno == EAGAIN) continue;
else error("ERROR on accept");
}
if((pid = fork()) > 0)
{ // this is parent process
close(new_socket);
}
else if(pid == 0)
{ // this is a child process that will handle an incoming request
long_pid = (long) getpid(); // current child's PID
close(server_socket);
server_socket = -1; //closing parent socket
printf("A new connection accepted from blablabla, port %d by process %ld\n", port_number, long_pid);
// ---- doing some staff, running the program
EDIT: while((msg_size = read(new_socket, received_data, BUFFER_SIZE)) >0)
// ---- when Im done:
printf("closing newsock\n");
close(new_socket); // close the new socket
new_socket = -1;
exit(0);
}
}
else error("fork() failed");
}
// close the server
printf("closing an original socket\n");
close(server_socket); // close an original server socket
return 0;
}
I didnt have this problem before, when I was using nonblocking sockets. So problem is probably connected to them.

Answer 1

If I fill in the blanks to make this into a compilable example (please post an mcve next time)
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <errno.h>
#include <arpa/inet.h>
#define port_number 2222
void error(char const *Msg)
{
perror(Msg);
exit(1);
}
int main()
{
pid_t pid; long long_pid;
int server_socket, new_socket;
struct sockaddr_in server;
bzero((char *) &server, sizeof(server));
server_socket = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
if(server_socket < 0) error("ERROR opening socket");
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl(INADDR_ANY);
server.sin_port = htons(port_number);
if(bind(server_socket, (struct sockaddr *) &server, sizeof(struct sockaddr_in)) < 0) error("ERROR on binding");
if(listen(server_socket, 5) < 0) error("Failed to listen for connections.");
while(1)
{
struct sockaddr_in client;
unsigned int client_len = sizeof(struct sockaddr_in);
bzero((char *) &client, client_len);
if((new_socket = accept(server_socket, (struct sockaddr *) &client, &client_len)) < 0)
{
if(errno == EAGAIN) continue;
else error("ERROR on accept");
}
if((pid = fork()) > 0)
{ // this is parent process
close(new_socket);
}
else if(pid == 0)
{ // this is a child process that will handle an incoming request
long_pid = (long) getpid(); // current child's PID
close(server_socket);
server_socket = -1; //closing parent socket
printf("A new connection accepted from blablabla, port %d by process %ld\n", port_number, long_pid);
// ---- doing some staff, running the program
// ---- when Im done:
printf("closing newsock\n");
close(new_socket); // close the new socket
new_socket = -1;
_exit(0);
}
else error("fork() failed");
}
// close the server
printf("closing an original socket\n");
close(server_socket); // close an original server socket
return 0;
}
it seems to work without any issues.
Obviously you're establishing the listening socket with error checks in the parent process and the parent process then isn't doing anything with the listening socket that closes it, so you shouldn't be getting that error from the parent process.
My guess is you're probably mistakenly continuing the loop in the child (in the part you're not showing).