Don't treat POLLRDHUP as fatal unless we can't receive data after it, and return errors from wait_select functions when they close the socket

src/ckpool.c

@@ -504,6 +504,7 @@ int read_socket_line(connsock_t *cs, float *timeout)
 	tv_t start, now;
 	size_t buflen;
 	int ret = -1;
+	bool polled;
 	float diff;
 
 	if (unlikely(cs->fd < 0))
@@ -528,6 +529,7 @@ rewait:
 		goto out;
 	}
 	ret = wait_recv_select(cs->fd, eom ? 0 : *timeout);
+	polled = true;
 	if (ret < 1) {
 		if (!ret) {
 			if (eom)
@@ -551,12 +553,16 @@ rewait:
 			/* No more to read or closed socket after valid message */
 			if (eom)
 				break;
-			/* Have we used up all the timeout yet? */
-			if (*timeout >= 0 && (errno == EAGAIN || errno == EWOULDBLOCK || !ret))
+			/* Have we used up all the timeout yet? If polled is
+			 * set that means poll has said there should be
+			 * something to read and if we get nothing it means the
+			 * socket is closed. */
+			if (!polled && *timeout >= 0 && (errno == EAGAIN || errno == EWOULDBLOCK || !ret))
 				goto rewait;
 			LOGERR("Failed to recv in read_socket_line");
 			goto out;
 		}
+		polled = false;
 		buflen = cs->bufofs + ret + 1;
 		while (42) {
 			newbuf = realloc(cs->buf, buflen);

src/libckpool.c

@@ -919,8 +919,10 @@ int _wait_read_select(int *sockd, float timeout)
 	sfd.events = POLLIN | POLLRDHUP;
 	timeout *= 1000;
 	ret = poll(&sfd, 1, timeout);
-	if (ret > 0 && sfd.revents & (POLLERR))
+	if (ret > 0 && sfd.revents & (POLLERR)) {
+		ret = -1;
 		_Close(sockd);
+	}
 out:
 	return ret;
 }
@@ -936,8 +938,12 @@ int _wait_recv_select(int *sockd, float timeout)
 	sfd.events = POLLIN | POLLRDHUP;
 	timeout *= 1000;
 	ret = poll(&sfd, 1, timeout);
-	if (ret > 0 && sfd.revents & (POLLHUP | POLLRDHUP | POLLERR))
+	/* If POLLRDHUP occurs, we may still have data to read so let recv()
+	 * after this determine if the socket can still be used. */
+	if (ret > 0 && sfd.revents & (POLLHUP | POLLERR)) {
+		ret = -1;
 		_Close(sockd);
+	}
 out:
 	return ret;
 }