Sorry if this is already known: on a RH 7.0 system with kernel 2.4.2
or 2.4.3, a select on an unconnected socket incorrectly says that the
socket is ready for input and output. Of course, reading from the socket
file descriptor returns -1 and errno is set to ENOTCONN as shown in
the strace output:
socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 3
select(4, [3], [3], [3], {0, 0}) = 2 (in [3], out [3], left {0, 0})
read(3, 0xbffff668, 1024) = -1 ENOTCONN (Transport endpoint is not connected)
I attached a small example program to reproduce the bug.
Thanks,
Radu Greab
PS: please CC me your eventual replies as I'm not subscribed to the
list.
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
int main(int argc, char **argv) {
fd_set rfds, wfds, efds;
int s, rc;
struct timeval timeout;
char buf[1025];
s = socket(PF_INET, SOCK_STREAM, 0);
if (s == -1) {
perror("couldn't create socket");
return -1;
}
FD_ZERO(&rfds);
FD_SET(s, &rfds);
FD_ZERO(&wfds);
FD_SET(s, &wfds);
FD_ZERO(&efds);
FD_SET(s, &efds);
timeout.tv_sec = timeout.tv_usec = 0;
rc = select(s + 1, &rfds, &wfds, &efds, &timeout);
if (rc == -1) {
perror("select");
return -1;
}
printf("select result=%d\n", rc);
if (FD_ISSET(s, &rfds)) {
rc = read(s, buf, 1024);
if (rc == -1) {
perror("read");
return -1;
}
printf("read result=%d\n", rc);
}
return 0;
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sat Mar 31 2001 - 10:49:13 EST