CODEWITHSUNDEEP
clinuxsocketssignals
Topilski Alexandr
Topilski Alexandr

Reputation: 669

How to prevent SIGPIPE in sendfile function

Good day i have small http server where i have threadpool current connections, when i do send file in thread i get signal SIGPIPE and my server crash. Part of code: //in thread: 

 detail::create_headers(headers,stat_buf.st_size,mime_types::extension_to_type(extension.c_str()));
    if(detail::write_to_client(fd_client,headers,unicode_strlen(headers))!=-1)
    {
        while(offset!=stat_buf.st_size)
        {
            if(sendfile(fd_client,src,&offset,stat_buf.st_size)==-1)
            {
                DEBUG_MSG_FORMAT("sendfile error: %d",errno);
                break;
            }
        }
    }
//and : 

size_t write_to_client(int fd_client,const void *buf,size_t len)
{
    int optval = 1;
    setsockopt (fd_client, SOL_TCP, TCP_CORK, &optval, sizeof (int));
    size_t result = write(fd_client,buf,len);
    if(result==-1)
    {
        DEBUG_MSG_FORMAT("write error: %d",errno);
    }
    optval = 0;
    setsockopt (fd_client, SOL_TCP, TCP_CORK, &optval, sizeof (int));
                return result;
}
How can i handle or prevent SIGPIPE in thread?

Upvotes: 2

Views: 1015

Answers (2)

zeuz
zeuz

Reputation: 1

Seemingly, sendfile() does not have any flags (like e.g. send() does with MSG_NOSIGNAL), so one option is to disable SIGPIPE using signal(SIGPIPE, SIG_IGN), but that does not keep debuggers like gdb to stop your process on SIGPIPE. If you want gdb to keep your code running, try handle SIGPIPE nostop in gdb or replace sendfile() by a read/send loop with MSG_NOSIGNAL flags.

Upvotes: 0

cnicutar
cnicutar

Reputation: 182649

How can i handle or prevent SIGPIPE in thread?

At least three ways:

  • Use the SO_NOSIGPIPE socket option
  • Use the MSG_NOSIGNAL flag for send(2) (Linux-specific)
  • Ignore the sigpipe (using SIG_IGN) or establish a real handler for it

I would go for the first one if possible (it's not portable). Instead of the signal you'll get a return of -1 with errno = EPIPE.

Upvotes: 2

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