5 files changed, 33 insertions, 32 deletions

diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 04939e7..13059f1 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -314,7 +314,7 @@ int udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
 
 void udhcp_sp_setup(void) FAST_FUNC;
 void udhcp_sp_fd_set(struct pollfd *pfds, int extra_fd) FAST_FUNC;
-int udhcp_sp_read(struct pollfd *pfds) FAST_FUNC;
+int udhcp_sp_read(void) FAST_FUNC;
 
 int udhcp_read_interface(const char *interface, int *ifindex, uint32_t *nip, uint8_t *mac) FAST_FUNC;
 
diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index 35c99e8..289df66 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -1375,13 +1375,12 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
 			/* yah, I know, *you* say it would never happen */
 			timeout = INT_MAX;
 			continue; /* back to main loop */
-		} /* if select timed out */
+		} /* if poll timed out */
 
-		/* select() didn't timeout, something happened */
+		/* poll() didn't timeout, something happened */
 
 		/* Is it a signal? */
-		/* note: udhcp_sp_read checks poll result before reading */
-		switch (udhcp_sp_read(pfds)) {
+		switch (udhcp_sp_read()) {
 		case SIGUSR1:
 			client_config.first_secs = 0; /* make secs field count from 0 */
 			already_waited_sec = 0;
@@ -1416,7 +1415,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
 		}
 
 		/* Is it a packet? */
-		if (listen_mode == LISTEN_NONE || !pfds[1].revents)
+		if (!pfds[1].revents)
 			continue; /* no */
 
 		{
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 35694fb..90b07bf 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -1574,13 +1574,12 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 			/* yah, I know, *you* say it would never happen */
 			timeout = INT_MAX;
 			continue; /* back to main loop */
-		} /* if select timed out */
+		} /* if poll timed out */
 
-		/* select() didn't timeout, something happened */
+		/* poll() didn't timeout, something happened */
 
 		/* Is it a signal? */
-		/* note: udhcp_sp_read checks poll result before reading */
-		switch (udhcp_sp_read(pfds)) {
+		switch (udhcp_sp_read()) {
 		case SIGUSR1:
 			client_config.first_secs = 0; /* make secs field count from 0 */
 			already_waited_sec = 0;
@@ -1615,7 +1614,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 		}
 
 		/* Is it a packet? */
-		if (listen_mode == LISTEN_NONE || !pfds[1].revents)
+		if (!pfds[1].revents)
 			continue; /* no */
 
 		{
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 0932395..db3ab4f 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -915,20 +915,18 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
 
 		udhcp_sp_fd_set(pfds, server_socket);
 		tv = timeout_end - monotonic_sec();
-		retval = 0;
-		if (!server_config.auto_time || tv > 0) {
-			retval = poll(pfds, 2, server_config.auto_time ? tv * 1000 : -1);
-		}
-		if (retval == 0) {
-			write_leases();
-			goto continue_with_autotime;
-		}
-		if (retval < 0 && errno != EINTR) {
-			log1("error on select");
-			continue;
+		/* Block here waiting for either signal or packet */
+		retval = safe_poll(pfds, 2, server_config.auto_time ? tv * 1000 : -1);
+		if (retval <= 0) {
+			if (retval == 0) {
+				write_leases();
+				goto continue_with_autotime;
+			}
+			/* < 0 and not EINTR: should not happen */
+			bb_perror_msg_and_die("poll");
 		}
 
-		switch (udhcp_sp_read(pfds)) {
+		if (pfds[0].revents) switch (udhcp_sp_read()) {
 		case SIGUSR1:
 			bb_error_msg("received %s", "SIGUSR1");
 			write_leases();
@@ -938,12 +936,16 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
 			bb_error_msg("received %s", "SIGTERM");
 			write_leases();
 			goto ret0;
-		case 0: /* no signal: read a packet */
-			break;
-		default: /* signal or error (probably EINTR): back to select */
-			continue;
 		}
 
+		/* Is it a packet? */
+		if (!pfds[1].revents)
+			continue; /* no */
+
+		/* Note: we do not block here, we block on poll() instead.
+		 * Blocking here would prevent SIGTERM from working:
+		 * socket read inside this call is restarted on caught signals.
+		 */
 		bytes = udhcp_recv_kernel_packet(&packet, server_socket);
 		if (bytes < 0) {
 			/* bytes can also be -2 ("bad packet data") */
diff --git a/networking/udhcp/signalpipe.c b/networking/udhcp/signalpipe.c
index b101b4c..2ff78f0 100644
--- a/networking/udhcp/signalpipe.c
+++ b/networking/udhcp/signalpipe.c
@@ -40,6 +40,7 @@ void FAST_FUNC udhcp_sp_setup(void)
 	xpiped_pair(signal_pipe);
 	close_on_exec_on(signal_pipe.rd);
 	close_on_exec_on(signal_pipe.wr);
+	ndelay_on(signal_pipe.rd);
 	ndelay_on(signal_pipe.wr);
 	bb_signals(0
 		+ (1 << SIGUSR1)
@@ -61,20 +62,20 @@ void FAST_FUNC udhcp_sp_fd_set(struct pollfd pfds[2], int extra_fd)
 		pfds[1].fd = extra_fd;
 		pfds[1].events = POLLIN;
 	}
+	/* this simplifies "is extra_fd ready?" tests elsewhere: */
+	pfds[1].revents = 0;
 }
 
 /* Read a signal from the signal pipe. Returns 0 if there is
  * no signal, -1 on error (and sets errno appropriately), and
  * your signal on success */
-int FAST_FUNC udhcp_sp_read(struct pollfd pfds[2])
+int FAST_FUNC udhcp_sp_read(void)
 {
 	unsigned char sig;
 
-	if (!pfds[0].revents)
-		return 0;
-
+	/* Can't block here, fd is in nonblocking mode */
 	if (safe_read(signal_pipe.rd, &sig, 1) != 1)
-		return -1;
+		return 0;
 
 	return sig;
 }