Program received signal SIGPIPE, Broken pipe

问题

I write a client program based on posix sockets. The program creates multiple threads and is going to lock the server. But during debug in gdb time the program gives an info (error)

(gdb) n
Program received signal SIGPIPE, Broken pipe. [Switching to Thread 0xb74c0b40 (LWP 4864)] 0xb7fdd424 in __kernel_vsyscall () 
(gdb)

Here's the code:

#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

int get_hostname_by_ip(char* h , char* ip)
{
    struct hostent *he;
    struct in_addr **addr_list;
    int i;

    if ((he = gethostbyname(h)) == NULL) 
    {
        perror("gethostbyname");
        return 1;
    }
    addr_list = (struct in_addr **) he->h_addr_list;
    for(i = 0; addr_list[i] != NULL; i++) 
    {
        strcpy(ip , inet_ntoa(*addr_list[i]) );
        return 0;
    }

    return 1;
}

void client(char* h, int s)
{
    int fd;
    struct sockaddr_in addr;
    char ch[]="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
    fd = socket(AF_INET, SOCK_STREAM, 0);
    addr.sin_family=AF_INET;
    char* ip = new char[20];
    get_hostname_by_ip(h, ip);
    addr.sin_addr.s_addr=inet_addr(ip);
    int port = 80;
    addr.sin_port=htons(port);
    if(connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) 
    {
        perror("connect error");
        return;
    }
    while(1)
    {
        if(send(fd, ch, sizeof(ch), 0) < 0)
        {   
            perror("send");
        }
    }
    //char buffer[1024];
    //if(recv(fd, &buffer, sizeof(buffer), 0) < 0)
    //{ 
    //  perror("recive");
    //}

    //printf("nReply from Server: %s\n", buffer);
    close(fd);
}

struct info
{
    char* h;
    int c;
};


void* thread_entry_point(void* i)
{
    info* in = (info*)i;
    client(in->h, in->c);
}

int main(int argc, char** argv)
{
    int s = atoi(argv[2]);
    pthread_t t[s];
    info in = {argv[1], s};
    for(int i = 0; i < s; ++i)
    {
        pthread_create(&t[i], NULL, thread_entry_point, (void*)&in);
    }
    pthread_join(t[0], NULL);

    return 0;
}

What it is and what to do?

回答1:

The process received a SIGPIPE. The default behaviour for this signal is to end the process.

A SIGPIPE is sent to a process if it tried to write to a socket that had been shutdown for writing or isn't connected (anymore).

To avoid that the program ends in this case, you could either

make the process ignore SIGPIPE

#include <signal.h>

int main(void)
{
  sigaction(SIGPIPE, &(struct sigaction){SIG_IGN}, NULL);

  ...

install an explicit handler for SIGPIPE (typically doing nothing):

#include <signal.h>

void sigpipe_handler(int unused)
{
}

int main(void)
{
  sigaction(SIGPIPE, &(struct sigaction){sigpipe_handler}, NULL);

  ...

In both cases send*()/write() would return -1 and set errno to EPIPE.

回答2:

When debugging with 'gdb', it is possible to manually disable SIGPIPE as follows:

(gdb) handle SIGPIPE nostop

回答3:

A workaround for SIGPIPE, you can ignore this signal by this code:

#include <signal.h>

/* Catch Signal Handler functio */
void signal_callback_handler(int signum){

        printf("Caught signal SIGPIPE %d\n",signum);
}

in your code (main or globally)

/* Catch Signal Handler SIGPIPE */
signal(SIGPIPE, signal_callback_handler);

回答4:

You have written to a connection that has already been closed by the peer.

回答5:

I sort of experienced the same problem and it let me to this SO post. I got sporadic SIGPIPE signals causing crashes of my fastcgi C program run by nginx. I tried to signal(SIGPIPE, SIG_IGN); without luck, it kept crashing.

The reason was that nginx's temp dir had a permission problem. Fixing the permissions solved the SIGPIPE problem. Details here on how to fix and more here.

来源：https://stackoverflow.com/questions/18935446/program-received-signal-sigpipe-broken-pipe

标签

sockets

gdb

pthreads

sigpipe