tcpip: use poll to wait for incomming data

This uses poll to wait for incomming data.
This also used to detect errors and avoid using an invalid
file descriptor.
This should improve the error handling when a connection is close
by the server or the client.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>

controllers/tcpip.c

@@ -382,12 +382,25 @@ static int _tcpip_read(int fd, void *data, size_t len)
 	size_t remaining;
 	size_t offset;
 	size_t recvd;
+	struct pollfd pollfd;
 
 	if (0 == len) {
 		return 0;
 	}
 
+	pollfd.fd = fd;
+	pollfd.events = POLLIN | POLLHUP | POLLERR | POLLHUP | POLLNVAL;
 	for(remaining = len, offset = 0, recvd = 0; remaining; remaining -= recvd, offset += recvd, recvd = 0) {
+		ret = poll(&pollfd, 1, -1);
+		if (ret <= 0) {
+			pr_err("%s(): failed to execute poll\n", __func__);
+			return -errno;
+		}
+
+		/* The socket could not be used anymore */
+		if (pollfd.revents & (POLLHUP | POLLERR | POLLHUP | POLLNVAL))
+			return -ECONNRESET;
+
 		ret = read(fd, &((uint8_t *)data)[offset], remaining);
 		if (-1 == ret) {
 			if (EAGAIN == errno) {