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>

1 files changed, 22 insertions, 9 deletions

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;