[PATCH lib/libxtrans] If Socket is getting interrupted with signal EINTR, after re attempts we are closing socket connection, which is wrong.

[Arvind Umrao]

Code changes are integrated in Solaris and now I am trying to give back to
community. If Socket is getting interrupted with signal EINTR, we should keep
socket in progress state(TRANS_IN_PROGRESS) instead of trying again to
connect(TRANS_TRY_CONNECT_AGAIN). When we close the socket connection on signal
EINTR and retry, we will end up in same old state and stuck in loop. As per
documentation if Connect() is interrupted by a signal that is caught, while
blocked waiting to establish a connection, connect() shall fail and set
connect() to [EINTR], but the connection request shall not be aborted, and the
connection shall be established asynchronously. When the connection has been
established asynchronously, select() and poll() shall indicate that the file
descriptor for the socket is ready for writing.

For both blocking and non blocking, if connect()interrupted with Signal EINTR,
it should return TRANS_IN_PROGRESS. In Unix Network Programming, volume 1,
section 5.9, W. Richard Stevens states:
What we are doing […] is restarting the interrupted system call ourself.
This is fine for accept, along with the functions such as read, write, select
and open. But there is one function that we cannot restart ourself: connect. If
this function returns EINTR, we cannot call it again, as doing so will return
an immediate error. When connect is interrupted by a caught signal and is not
automatically restarted, we must call "Select" to wait for the connection to
complete, as we describe in section 15.3.

Refer http://www.madore.org/~david/computers/connect-intr.html

Signed-off-by: Arvind Umrao <arvind.umrao at oracle.com>
---
 Xtranssock.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/Xtranssock.c b/Xtranssock.c
index dfa41cf..eaef6f0 100644
--- a/Xtranssock.c
+++ b/Xtranssock.c
@@ -1717,7 +1717,7 @@ TRANS(SocketINETConnect) (XtransConnInfo ciptr, char *host, char *port)
 	 * was non-blocking and we should poll using select
 	 *
 	 * If the error was EINTR, the connect was interrupted and we
-	 * should try again.
+	 * should poll using select.
 	 *
 	 * If multiple addresses are found for a host then we should
 	 * try to connect again with a different address for a larger
@@ -1727,7 +1727,7 @@ TRANS(SocketINETConnect) (XtransConnInfo ciptr, char *host, char *port)
 	 * only affect one of a set of addresses.
 	 */
 
-	if (olderrno == ECONNREFUSED || olderrno == EINTR
+	if (olderrno == ECONNREFUSED 
 #if defined(IPv6) && defined(AF_INET6)
 	  || (((addrlist->addr->ai_next != NULL) ||
 	        (addrlist->addr != addrlist->firstaddr)) &&
@@ -1740,7 +1740,7 @@ TRANS(SocketINETConnect) (XtransConnInfo ciptr, char *host, char *port)
 #endif
 	    )
 	    res = TRANS_TRY_CONNECT_AGAIN;
-	else if (olderrno == EWOULDBLOCK || olderrno == EINPROGRESS)
+	else if (olderrno == EWOULDBLOCK || olderrno == EINPROGRESS || olderrno == EINTR)
 	    res = TRANS_IN_PROGRESS;
 	else
 	{
@@ -2022,13 +2022,11 @@ TRANS(SocketUNIXConnect) (XtransConnInfo ciptr, char *host, char *port)
 	     * was non-blocking and we should poll using select
 	     *
 	     * If the error was EINTR, the connect was interrupted and we
-	     * should try again.
+	     * should poll using select.
 	     */
 
-	    if (olderrno == EWOULDBLOCK || olderrno == EINPROGRESS)
+	    if (olderrno == EWOULDBLOCK || olderrno == EINPROGRESS || olderrno == EINTR)
 		return TRANS_IN_PROGRESS;
-	    else if (olderrno == EINTR)
-		return TRANS_TRY_CONNECT_AGAIN;
 	    else if (olderrno == ENOENT || olderrno == ECONNREFUSED) {
 		/* If opening as abstract socket failed, try again normally */
 		if (abstract) {
-- 
1.7.9.2