libbb: introduce bb_signals and bb_signals_recursive,

which sets same handler for many signals. sig_catch is nuked
(bb_signals_recursive is more descriptive name).
*: use them as appropriate. 

function                                             old     new   delta
bb_signals_recursive                                   -      95     +95
bb_signals                                             -      52     +52
run_command                                          258     273     +15
svlogd_main                                         1368    1377      +9
runsv_main                                          1746    1752      +6
runsvdir_main                                       1643    1646      +3
UNSPEC_print                                          64      66      +2
time_main                                           1128    1127      -1
...
resize_main                                          246     210     -36
sig_catch                                             63       -     -63
set_fatal_sighandler                                  85      14     -71
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 5/24 up/down: 182/-548)        Total: -366 bytes

miscutils/less.c

@@ -1355,8 +1355,10 @@ int less_main(int argc, char **argv)
 		empty_line_marker = "";
 
 	tcgetattr(kbd_fd, &term_orig);
-	signal(SIGTERM, sig_catcher);
-	signal(SIGINT, sig_catcher);
+	bb_signals(0
+		+ (1 << SIGTERM)
+		+ (1 << SIGINT)
+		, sig_catcher);
 	term_less = term_orig;
 	term_less.c_lflag &= ~(ICANON | ECHO);
 	term_less.c_iflag &= ~(IXON | ICRNL);

miscutils/microcom.c

@@ -99,10 +99,12 @@ int microcom_main(int argc, char **argv)
 	}
 
 	// setup signals
-	sig_catch(SIGHUP,  signal_handler);
-	sig_catch(SIGINT,  signal_handler);
-	sig_catch(SIGTERM, signal_handler);
-	sig_catch(SIGPIPE, signal_handler);
+	bb_signals_recursive(0
+			+ (1 << SIGHUP)
+			+ (1 << SIGINT)
+			+ (1 << SIGTERM)
+			+ (1 << SIGPIPE)
+			, signal_handler);
 
 	// error exit code if we fail to open the device
 	signalled = 1;

miscutils/time.c

@@ -61,7 +61,7 @@ static const char long_format[] ALIGN1 =
    Return 0 on error, 1 if ok.  */
 
 /* pid_t is short on BSDI, so don't try to promote it.  */
-static int resuse_end(pid_t pid, resource_t * resp)
+static int resuse_end(pid_t pid, resource_t *resp)
 {
 	int status;
 	pid_t caught;
@@ -69,7 +69,7 @@ static int resuse_end(pid_t pid, resource_t * resp)
 	/* Ignore signals, but don't ignore the children.  When wait3
 	   returns the child process, set the time the command finished. */
 	while ((caught = wait3(&status, 0, &resp->ru)) != pid) {
-		if (caught == -1)
+		if (caught == -1 && errno != EINTR)
 			return 0;
 	}
 	resp->elapsed_ms = (monotonic_us() / 1000) - resp->elapsed_ms;
@@ -373,24 +373,26 @@ static void summarize(const char *fmt, char **command, resource_t * resp)
 
 /* Run command CMD and return statistics on it.
    Put the statistics in *RESP.  */
-static void run_command(char *const *cmd, resource_t * resp)
+static void run_command(char *const *cmd, resource_t *resp)
 {
 	pid_t pid;			/* Pid of child.  */
-	__sighandler_t interrupt_signal, quit_signal;
+	void (*interrupt_signal)(int);
+	void (*quit_signal)(int);
 
 	resp->elapsed_ms = monotonic_us() / 1000;
 	pid = vfork();		/* Run CMD as child process.  */
 	if (pid < 0)
 		bb_error_msg_and_die("cannot fork");
-	else if (pid == 0) {	/* If child.  */
+	if (pid == 0) {	/* If child.  */
 		/* Don't cast execvp arguments; that causes errors on some systems,
 		   versus merely warnings if the cast is left off.  */
 		BB_EXECVP(cmd[0], cmd);
-		bb_error_msg("cannot run %s", cmd[0]);
-		_exit(errno == ENOENT ? 127 : 126);
+		xfunc_error_retval = (errno == ENOENT ? 127 : 126);
+		bb_error_msg_and_die("cannot run %s", cmd[0]);
 	}
 
 	/* Have signals kill the child but not self (if possible).  */
+//TODO: just block all sigs? and reenable them in the very end in main?
 	interrupt_signal = signal(SIGINT, SIG_IGN);
 	quit_signal = signal(SIGQUIT, SIG_IGN);
 

miscutils/watchdog.c

@@ -47,8 +47,10 @@ int watchdog_main(int argc, char **argv)
 		bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
 	}
 
-	signal(SIGHUP, watchdog_shutdown);
-	signal(SIGINT, watchdog_shutdown);
+	bb_signals(0
+		+ (1 << SIGHUP)
+		+ (1 << SIGINT)
+		, watchdog_shutdown);
 
 	/* Use known fd # - avoid needing global 'int fd' */
 	xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);