libbb: introduse and use signal_[no_]SA_RESTART_empty_mask and sigaction_set

signal_SA_RESTART_empty_mask                           -      65     +65
signal_no_SA_RESTART_empty_mask                        -      54     +54
dd_main                                             1325    1369     +44
sigaction_set                                          -      19     +19
dname_enc                                            373     377      +4
UNSPEC_print                                          64      66      +2
setsignal                                            296     294      -2
bb_signals_recursive                                  95      92      -3
bb_askpass                                           367     361      -6
inetd_main                                          1810    1797     -13
rx_main                                              912     883     -29
sigdelset                                             32       -     -32
__sigdelset                                           32       -     -32
__GI_sigdelset                                        32       -     -32
sighup_handler                                        84      37     -47
arping_main                                         1844    1797     -47
fsck_main                                           1869    1807     -62
run_list                                            1917    1844     -73
vlock_main                                           492     409     -83
progressmeter                                        883     798     -85
handle_incoming_and_exit                            2737    2651     -86
------------------------------------------------------------------------------
(add/remove: 3/3 grow/shrink: 3/12 up/down: 188/-632)        Total: -444 bytes

2 files changed, 29 insertions, 3 deletions

diff --git a/libbb/bb_askpass.c b/libbb/bb_askpass.c
index fd12f92dc..3ad0e97cd 100644
--- a/libbb/bb_askpass.c
+++ b/libbb/bb_askpass.c
@@ -45,7 +45,7 @@ char *bb_askpass(int timeout, const char *prompt)
         sa.sa_handler = askpass_timeout;
         sigaction(SIGINT, &sa, &oldsa);
         if (timeout) {
-                sigaction(SIGALRM, &sa, NULL);
+                sigaction_set(SIGALRM, &sa);
                 alarm(timeout);
         }
 
@@ -68,7 +68,7 @@ char *bb_askpass(int timeout, const char *prompt)
         if (timeout) {
                 alarm(0);
         }
-        sigaction(SIGINT, &oldsa, NULL);
+        sigaction_set(SIGINT, &oldsa);
 
         tcsetattr(STDIN_FILENO, TCSANOW, &oldtio);
         bb_putchar('\n');
diff --git a/libbb/signals.c b/libbb/signals.c
index a327e87c8..719beab63 100644
--- a/libbb/signals.c
+++ b/libbb/signals.c
@@ -11,6 +11,12 @@
 
 #include "libbb.h"
 
+/* Saves 2 bytes on x86! Oh my... */
+int sigaction_set(int signum, const struct sigaction *act)
+{
+        return sigaction(signum, act, NULL);
+}
+
 void bb_signals(int sigs, void (*f)(int))
 {
         int sig_no = 0;
@@ -40,7 +46,7 @@ void bb_signals_recursive(int sigs, void (*f)(int))
         while (sigs) {
                 if (sigs & bit) {
                         sigs &= ~bit;
-                        sigaction(sig_no, &sa, NULL);
+                        sigaction_set(sig_no, &sa);
                 }
                 sig_no++;
                 bit <<= 1;
@@ -87,3 +93,23 @@ void kill_myself_with_sig(int sig)
         raise(sig);
         _exit(1); /* Should not reach it */
 }
+
+void signal_SA_RESTART_empty_mask(int sig, void (*handler)(int))
+{
+        struct sigaction sa;
+        memset(&sa, 0, sizeof(sa));
+        /*sigemptyset(&sa.sa_mask);*/
+        sa.sa_flags = SA_RESTART;
+        sa.sa_handler = handler;
+        sigaction_set(sig, &sa);
+}
+
+void signal_no_SA_RESTART_empty_mask(int sig, void (*handler)(int))
+{
+        struct sigaction sa;
+        memset(&sa, 0, sizeof(sa));
+        /*sigemptyset(&sa.sa_mask);*/
+        /*sa.sa_flags = 0;*/
+        sa.sa_handler = handler;
+        sigaction_set(sig, &sa);
+}