sendto generates SIGSEGV

Oliver Kowalke (oliver.kowalke@t-online.de)
Sun, 29 Jul 2001 23:27:29 +0200


Hi,

I've written an c++ class which wrappes a socket.. With function writen()
you can write to an TCP and UDP socket ( TCP : pointer to stuct sockaddr ==
NULL; UDP : pointer to struct sockaddr != NULL). If I use this function
with TCP sockets all works. If I call this function for an UDP socket it
generates an SIGSEGV signal.
What is wrong?

with regards,
Oliver

ssize_t writen( const void * vptr, size_t n, struct sockaddr * to)
{
size_t nleft = n;
ssize_t nwritten;
const char *ptr = static_cast< const char * >( vptr);

struct sigaction new_sa;
struct sigaction old_sa;

new_sa.sa_handler = SIG_IGN;
::sigemptyset( & new_sa.sa_mask);
new_sa.sa_flags = 0;
::sigaction( SIGPIPE, & new_sa, & old_sa);

while ( nleft > 0)
{

if ( ( nwritten = ::sendto( m_handle, ptr, nleft, 0, to,
sizeof * to)

)<=0)
{
if ( errno == EINTR)
nwritten = 0; // and call sendto() again
else if ( errno == EPIPE)
{
::sigaction( SIGPIPE, & old_sa, 0);

return -1; // write to sock with
no readers (peer has the sock closed)

}
else
{
::sigaction( SIGPIPE, & old_sa, 0);
throw; // error
}
}

nleft -= nwritten;
ptr += nwritten;
}
::sigaction( SIGPIPE, & old_sa, 0); // set to its previous action

return n;
}

here the output of the generated core file:

Core was generated by 'lt-ogx 192.168.1.3 10000'.
Program terminated with signal 11, Segmentation fault.
rw_common (): write: Success.
warning: unable to get global thread event mask
[New Thread 1024 (LWP 32350)]
rw_common (): write: Success.
warning: stop_or_attach_thread: generic error
#0 0x0 in ?? ()
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