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

1 files changed, 7 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 3c53e5e68..505396b86 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -275,6 +275,7 @@ char *xrealloc_getcwd_or_warn(char *cwd);
 
 char *xmalloc_follow_symlinks(const char *path);
 
+
 enum {
         /* bb_signals(BB_SIGS_FATAL, handler) catches all signals which
          * otherwise would kill us, except for those resulting from bugs:
@@ -306,6 +307,12 @@ void bb_signals(int sigs, void (*f)(int));
  * and in a way that while signal handler is run, no other signals
  * will be blocked: */
 void bb_signals_recursive(int sigs, void (*f)(int));
+/* syscalls like read() will be interrupted with EINTR: */
+void signal_no_SA_RESTART_empty_mask(int sig, void (*handler)(int));
+/* syscalls like read() won't be interrupted (though select/poll will be): */
+void signal_SA_RESTART_empty_mask(int sig, void (*handler)(int));
+/* Will do sigaction(signum, act, NULL): */
+int sigaction_set(int signum, const struct sigaction *act);
 void sig_block(int);
 void sig_unblock(int);
 /* UNUSED: void sig_blocknone(void); */