dhcp: get rid of static data signal_pipe

function                                             old     new   delta
udhcp_sp_setup                                        65     110     +45
udhcp_sp_fd_set                                       60      59      -1
udhcpd_main                                         1442    1437      -5
udhcpc_main                                         2684    2679      -5
signal_pipe                                            8       -      -8
packed_usage                                       33292   33284      -8
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/4 up/down: 45/-27)             Total: 18 bytes
   text	   data	    bss	    dec	    hex	filename
 952746	    481	   7296	 960523	  ea80b	busybox_old
 952768	    481	   7288	 960537	  ea819	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 36 insertions, 23 deletions

diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index 15e9f3924..02766ba16 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -1174,6 +1174,10 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
         client_data.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
         client_data.sockfd = -1;
 
+        /* Make sure fd 0,1,2 are open */
+        /* Set up the signal pipe on fds 3,4 - must be before openlog() */
+        udhcp_sp_setup();
+
         /* Parse command line */
         opt = getopt32long(argv, "^"
                 /* O,x: list; -T,-t,-A take numeric param */
@@ -1268,14 +1272,10 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                 logmode |= LOGMODE_SYSLOG;
         }
 
-        /* Make sure fd 0,1,2 are open */
-        bb_sanitize_stdio();
         /* Create pidfile */
         write_pidfile(client_data.pidfile);
         /* Goes to stdout (unless NOMMU) and possibly syslog */
         bb_info_msg("started, v"BB_VER);
-        /* Set up the signal pipe */
-        udhcp_sp_setup();
 
         client_data.state = INIT_SELECTING;
         d6_run_script_no_option("deconfig");
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index cb85fa9e3..f040e93f7 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -1271,6 +1271,10 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
         client_data.sockfd = -1;
         str_V = "udhcp "BB_VER;
 
+        /* Make sure fd 0,1,2 are open */
+        /* Set up the signal pipe on fds 3,4 - must be before openlog() */
+        udhcp_sp_setup();
+
         /* Parse command line */
         opt = getopt32long(argv, "^"
                 /* O,x: list; -T,-t,-A take numeric param */
@@ -1385,14 +1389,10 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                 logmode |= LOGMODE_SYSLOG;
         }
 
-        /* Make sure fd 0,1,2 are open */
-        bb_sanitize_stdio();
         /* Create pidfile */
         write_pidfile(client_data.pidfile);
         /* Goes to stdout (unless NOMMU) and possibly syslog */
         bb_info_msg("started, v"BB_VER);
-        /* Set up the signal pipe */
-        udhcp_sp_setup();
         /* We want random_xid to be random... */
         srand(monotonic_us());
 
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 6e426e6a2..022b8721b 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -37,6 +37,8 @@
 //usage:        IF_FEATURE_UDHCP_PORT(
 //usage:     "\n        -P N    Use port N (default 67)"
 //usage:        )
+//usage:     "\nSignals:"
+//usage:     "\n        USR1    Update lease file"
 
 #include <netinet/ether.h>
 #include <syslog.h>
@@ -863,6 +865,10 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
         IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
         IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
 
+        /* Make sure fd 0,1,2 are open */
+        /* Setup the signal pipe on fds 3,4 - must be before openlog() */
+        udhcp_sp_setup();
+
         opt = getopt32(argv, "^"
                 "fSI:va:"IF_FEATURE_UDHCP_PORT("P:")
                 "\0"
@@ -904,9 +910,6 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
         if (server_data.auto_time > INT_MAX / 1000)
                 server_data.auto_time = INT_MAX / 1000;
 
-        /* Make sure fd 0,1,2 are open */
-        bb_sanitize_stdio();
-
         /* Create pidfile */
         write_pidfile(server_data.pidfile);
         /* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */
@@ -942,9 +945,6 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
                 goto ret;
         }
 
-        /* Setup the signal pipe */
-        udhcp_sp_setup();
-
  continue_with_autotime:
         timeout_end = monotonic_sec() + server_data.auto_time;
         while (1) { /* loop until universe collapses */
diff --git a/networking/udhcp/signalpipe.c b/networking/udhcp/signalpipe.c
index 2ff78f0f2..81d1fc01a 100644
--- a/networking/udhcp/signalpipe.c
+++ b/networking/udhcp/signalpipe.c
@@ -20,14 +20,14 @@
  */
 #include "common.h"
 
-/* Global variable: we access it from signal handler */
-static struct fd_pair signal_pipe;
+#define READ_FD  3
+#define WRITE_FD 4
 
 static void signal_handler(int sig)
 {
         int sv = errno;
         unsigned char ch = sig; /* use char, avoid dealing with partial writes */
-        if (write(signal_pipe.wr, &ch, 1) != 1)
+        if (write(WRITE_FD, &ch, 1) != 1)
                 bb_perror_msg("can't send signal");
         errno = sv;
 }
@@ -36,12 +36,25 @@ static void signal_handler(int sig)
  * and installs the signal handler */
 void FAST_FUNC udhcp_sp_setup(void)
 {
+        struct fd_pair signal_pipe;
+
+        /* All callers also want this, so... */
+        bb_sanitize_stdio();
+
         /* was socketpair, but it needs AF_UNIX in kernel */
         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);
+
+        /* usually we get fds 3 and 4, but if we get higher ones... */
+        if (signal_pipe.rd != READ_FD)
+                xmove_fd(signal_pipe.rd, READ_FD);
+        if (signal_pipe.wr != WRITE_FD)
+                xmove_fd(signal_pipe.wr, WRITE_FD);
+
+        close_on_exec_on(READ_FD);
+        close_on_exec_on(WRITE_FD);
+        ndelay_on(READ_FD);
+        ndelay_on(WRITE_FD);
+
         bb_signals(0
                 + (1 << SIGUSR1)
                 + (1 << SIGUSR2)
@@ -54,7 +67,7 @@ void FAST_FUNC udhcp_sp_setup(void)
  */
 void FAST_FUNC udhcp_sp_fd_set(struct pollfd pfds[2], int extra_fd)
 {
-        pfds[0].fd = signal_pipe.rd;
+        pfds[0].fd = READ_FD;
         pfds[0].events = POLLIN;
         pfds[1].fd = -1;
         if (extra_fd >= 0) {
@@ -74,7 +87,7 @@ int FAST_FUNC udhcp_sp_read(void)
         unsigned char sig;
 
         /* Can't block here, fd is in nonblocking mode */
-        if (safe_read(signal_pipe.rd, &sig, 1) != 1)
+        if (safe_read(READ_FD, &sig, 1) != 1)
                 return 0;
 
         return sig;