Re: bug report: select on unconnected sockets

From: Radu Greab (radu@netsoft.ro)
Date: Sat Mar 31 2001 - 11:26:00 EST

  • Next message: John Kodis: "Re: Linux connectivity trashed."

    On Sun, 1 Apr 2001 02:15 +1000, john slee wrote:
    > On Sat, Mar 31, 2001 at 06:44:20PM +0300, Radu Greab wrote:
    > > 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.
    >
    > bleah. which one is supposed to be right?

    I think that the Solaris one is right.

    >
    > linux 2.4
    > ---------
    > $ uname -a
    > Linux XXXXX 2.4.2-ac20 #8 Wed Mar 14 01:53:05 EST 2001 i686 unknown
    > $ ./t
    > select result=2
    > read: Transport endpoint is not connected

    Select says that the socket is ready for both input and output. A read
    results in ENOTCONN, a write results in EPIPE.

    > linux 2.2
    > ---------
    > $ uname -a
    > Linux XXXXX 2.2.18 #1 Thu Dec 21 21:13:10 EST 2000 i586 unknown
    > $ ./t
    > select result=1

    Select says that the socket is ready for output, but a write results
    in EPIPE.

    >
    > solaris
    > -------
    > $ uname -a
    > SunOS XXXXX 5.7 Generic_106541-07 sun4m sparc sun4m
    > $ ./t
    > select result=0

    And Digital Unix is right too:

    $ uname -a
    OSF1 XXX V4.0 1229 alpha
    $ ./a.out
    select result=0

    Thanks,
    Radu Greab
    -
    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 - 11:43:04 EST