From 5019b50b6dd568fcfce070ea926ab78cb2cef312 Mon Sep 17 00:00:00 2001
From: Davide Cavalca <dcavalca@centosproject.org>
Date: Dec 08 2022 00:24:35 +0000
Subject: Backport upstream PR to require signal handler in kill


---

diff --git a/SOURCES/1004-kill-support-mandating-userspace-signal-handler.patch b/SOURCES/1004-kill-support-mandating-userspace-signal-handler.patch
new file mode 100644
index 0000000..3c0684f
--- /dev/null
+++ b/SOURCES/1004-kill-support-mandating-userspace-signal-handler.patch
@@ -0,0 +1,93 @@
+diff -Naur a/misc-utils/kill.1 b/misc-utils/kill.1
+--- a/misc-utils/kill.1	2018-07-11 06:34:54.235003686 -0700
++++ b/misc-utils/kill.1	2022-12-07 16:19:17.911880263 -0800
+@@ -99,6 +99,8 @@
+ \fB\-p\fR, \fB\-\-pid\fR
+ Only print the process ID (PID) of the named processes, do not send any
+ signals.
++\fB\-r\fR, \fB\-\-require\-handler\fR
++Do not send the signal if it is not caught in userspace by the signalled process.
+ .TP
+ \fB\-\-verbose\fR
+ Print PID(s) that will be signaled with kill along with the signal.
+diff -Naur a/misc-utils/kill.c b/misc-utils/kill.c
+--- a/misc-utils/kill.c	2018-06-04 00:57:02.809445758 -0700
++++ b/misc-utils/kill.c	2022-12-07 16:21:16.372629866 -0800
+@@ -79,6 +79,7 @@
+ 		check_all:1,
+ 		do_kill:1,
+ 		do_pid:1,
++		require_handler:1,
+ 		use_sigval:1,
+ 		verbose:1;
+ };
+@@ -188,6 +189,7 @@
+ 	fputs(_(" -p, --pid              print pids without signaling them\n"), out);
+ 	fputs(_(" -l, --list[=<signal>]  list signal names, or convert a signal number to a name\n"), out);
+ 	fputs(_(" -L, --table            list signal names and numbers\n"), out);
++	fputs(_(" -r, --require-handler  do not send signal if signal handler is not present\n"), out);
+ 	fputs(_("     --verbose          print pids that will be signaled\n"), out);
+ 
+ 	fputs(USAGE_SEPARATOR, out);
+@@ -254,6 +256,10 @@
+ 			print_all_signals(stdout, 1);
+ 			exit(EXIT_SUCCESS);
+ 		}
++		if (!strcmp(arg, "-r") || !strcmp(arg, "--require-handler")) {
++			ctl->require_handler = 1;
++			continue;
++		}
+ 		if (!strcmp(arg, "-p") || !strcmp(arg, "--pid")) {
+ 			ctl->do_pid = 1;
+ 			if (ctl->do_kill)
+@@ -335,6 +341,32 @@
+ 	return rc;
+ }
+ 
++static int check_signal_handler(const struct kill_control *ctl)
++{
++	uintmax_t sigcgt = 0;
++	int rc = 0, has_hnd = 0;
++	struct path_cxt *pc;
++
++	if (!ctl->require_handler)
++		return 1;
++
++	pc = ul_new_procfs_path(ctl->pid, NULL);
++	if (!pc)
++		return -ENOMEM;
++
++	rc = procfs_process_get_stat_nth(pc, 34, &sigcgt);
++	if (rc)
++		return -EINVAL;
++
++	ul_unref_path(pc);
++
++	has_hnd = ((1UL << (ctl->numsig - 1)) & sigcgt) != 0;
++	if (ctl->verbose && !has_hnd)
++		printf(_("not signalling pid %d, it has no userspace handler for signal %d\n"), ctl->pid, ctl->numsig);
++
++	return has_hnd;
++}
++
+ int main(int argc, char **argv)
+ {
+ 	struct kill_control ctl = { .numsig = SIGTERM };
+@@ -354,6 +386,8 @@
+ 		errno = 0;
+ 		ctl.pid = strtol(ctl.arg, &ep, 10);
+ 		if (errno == 0 && ep && *ep == '\0' && ctl.arg < ep) {
++			if (check_signal_handler(&ctl) <= 0)
++				continue;
+ 			if (kill_verbose(&ctl) != 0)
+ 				nerrs++;
+ 			ct++;
+@@ -368,6 +402,8 @@
+ 
+ 			proc_processes_filter_by_name(ps, ctl.arg);
+ 			while (proc_next_pid(ps, &ctl.pid) == 0) {
++				if (check_signal_handler(&ctl) <= 0)
++					continue;
+ 				if (kill_verbose(&ctl) != 0)
+ 					nerrs++;
+ 				ct++;
diff --git a/SPECS/util-linux.spec b/SPECS/util-linux.spec
index a4c0fa1..44e20f1 100644
--- a/SPECS/util-linux.spec
+++ b/SPECS/util-linux.spec
@@ -273,6 +273,7 @@ Patch1000: 1000-setpriv-add-reset-env.patch
 Patch1001: 1001-losetup-avoid-infinite-busy-loop.patch
 Patch1002: 1002-losetup-increase-limit-of-setup-attempts.patch
 Patch1003: 1003-lib-loopdev-perform-retry-on-EAGAIN.patch
+Patch1004: 1004-kill-support-mandating-userspace-signal-handler.patch
 
 %description
 The util-linux package contains a large variety of low-level system
@@ -1129,6 +1130,8 @@ fi
 %changelog
 * Wed Dec 07 2022 Davide Cavalca <dcavalca@centosproject.org> 2.32.1-39.1
 - Merge upsteam changes in Hyperscale
+- Backport https://github.com/util-linux/util-linux/pull/1865 which adds
+  support to kill for mandating the precence of a userspace signal handler
 
 * Wed Nov 16 2022 Karel Zak <kzak@redhat.com> 2.32.1-39
 - fix #2141969 - Add --cont-clock feature for libuuid and uuidd