[PATCH] SOCK_CLOEXEC for opening sockets

[Chris Hegarty]

Alan,

> On 25 Jul 2018, at 08:24, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> 
> ...
> 
> As I said previously, the patch isn't complete so native code calling fork/exec may still have to deal with other file descriptors that are inherited into the child. I don't object to doing this in phases of course but somehow we have managed to get by for 20 years without this being an issue.

I added the following to the JIRA description to make this clear:

"This JIRA issue, by itself, does not completely resolve the problem
of native code calling fork/exec, it may still have to deal with other
file descriptors that are inherited by the child. Instead this JIRA
issue is targeted at the socket and channels areas only, other areas
should be tackled on a phased approach though separate JIRA
issues."

> The updates to the various site to use the NET_* functions are fine. However, I think the new functions in net_util_md.c could be cleaner. I think it would be better to fallback to socket/socketpair + fcntl when the initial call fails with EINVAL.

Agreed. How about this ( trying to reduce the ifdef blocks, and
keep them relatively clean ) :

---
JNIEXPORT int JNICALL
NET_Socket(int domain, int type, int protocol) {
    int s;
#if defined(SOCK_CLOEXEC)
    s = socket(domain, type | SOCK_CLOEXEC, protocol);
    if (s != -1 || (s == -1 && errno != EINVAL)) {
        return s;
    }
#endif
    s = socket(domain, type, protocol);
    if (s != -1) {
        // Best effort - return value is intentionally ignored since the socket
        // was successfully created.
        fcntl(s, F_SETFD, FD_CLOEXEC);
    }
    return s;
}
---

Updated webrev:
  http://cr.openjdk.java.net/~chegar/8207335/webrev.01/

-Chris.