7 files changed, 35 insertions, 34 deletions

diff --git a/examples/var_service/dhcpd_if/run b/examples/var_service/dhcpd_if/run
index de85dece0..a603bdc71 100755
--- a/examples/var_service/dhcpd_if/run
+++ b/examples/var_service/dhcpd_if/run
@@ -11,13 +11,13 @@ echo "* Upping iface $if"
 ip link set dev $if up
 
 >>udhcpd.leases
-sed 's/^interface.*$/interface '"$if/" -i udhcpc.conf
+sed 's/^interface.*$/interface '"$if/" -i udhcpd.conf
 
 echo "* Starting udhcpd"
 exec \
 env - PATH="$PATH" \
 softlimit \
 setuidgid root \
-udhcpd -f -vv udhcpc.conf
+udhcpd -f -vv udhcpd.conf
 
 exit $?
diff --git a/examples/var_service/dhcpd_if/udhcpc.conf b/examples/var_service/dhcpd_if/udhcpd.conf
index a81925970..a81925970 100644
--- a/examples/var_service/dhcpd_if/udhcpc.conf
+++ b/examples/var_service/dhcpd_if/udhcpd.conf
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 04939e707..13059f106 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 35c99e89c..289df66ee 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 35694fbe3..90b07bf4b 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 093239536..db3ab4f00 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 b101b4ce4..2ff78f0f2 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;
 }