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;