dcavalca / rpms / util-linux

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diff -Naur a/misc-utils/kill.1.adoc b/misc-utils/kill.1.adoc
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--- a/misc-utils/kill.1.adoc	2022-02-13 23:49:01.403480088 -0800
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+++ b/misc-utils/kill.1.adoc	2022-12-07 16:37:26.037765934 -0800
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@@ -62,6 +62,8 @@
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 Do not restrict the command-name-to-PID conversion to processes with the same UID as the present process.
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 *-p*, *--pid*::
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 Only print the process ID (PID) of the named processes, do not send any signals.
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+*-r*, *--require-handler*::
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+Do not send the signal if it is not caught in userspace by the signalled process.
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 *--verbose*::
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 Print PID(s) that will be signaled with *kill* along with the signal.
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 *-q*, *--queue* _value_::
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diff -Naur a/misc-utils/kill.c b/misc-utils/kill.c
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--- a/misc-utils/kill.c	2022-02-13 23:49:01.403480088 -0800
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+++ b/misc-utils/kill.c	2022-12-07 16:38:05.231013950 -0800
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@@ -93,6 +93,7 @@
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 		check_all:1,
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 		do_kill:1,
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 		do_pid:1,
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+		require_handler:1,
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 		use_sigval:1,
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 #ifdef UL_HAVE_PIDFD
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 		timeout:1,
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@@ -210,6 +211,7 @@
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 	fputs(_(" -p, --pid              print pids without signaling them\n"), out);
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 	fputs(_(" -l, --list[=<signal>]  list signal names, or convert a signal number to a name\n"), out);
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 	fputs(_(" -L, --table            list signal names and numbers\n"), out);
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+	fputs(_(" -r, --require-handler  do not send signal if signal handler is not present\n"), out);
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 	fputs(_("     --verbose          print pids that will be signaled\n"), out);
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 	fputs(USAGE_SEPARATOR, out);
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@@ -300,6 +302,10 @@
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 			print_all_signals(stdout, 1);
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 			exit(EXIT_SUCCESS);
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 		}
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+		if (!strcmp(arg, "-r") || !strcmp(arg, "--require-handler")) {
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+			ctl->require_handler = 1;
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+			continue;
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+		}
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 		if (!strcmp(arg, "-p") || !strcmp(arg, "--pid")) {
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 			ctl->do_pid = 1;
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 			if (ctl->do_kill)
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@@ -446,6 +452,32 @@
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 	return rc;
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 }
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+static int check_signal_handler(const struct kill_control *ctl)
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+{
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+	uintmax_t sigcgt = 0;
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+	int rc = 0, has_hnd = 0;
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+	struct path_cxt *pc;
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+
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+	if (!ctl->require_handler)
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+		return 1;
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+
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+	pc = ul_new_procfs_path(ctl->pid, NULL);
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+	if (!pc)
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+		return -ENOMEM;
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+
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+	rc = procfs_process_get_stat_nth(pc, 34, &sigcgt);
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+	if (rc)
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+		return -EINVAL;
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+
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+	ul_unref_path(pc);
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+
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+	has_hnd = ((1UL << (ctl->numsig - 1)) & sigcgt) != 0;
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+	if (ctl->verbose && !has_hnd)
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+		printf(_("not signalling pid %d, it has no userspace handler for signal %d\n"), ctl->pid, ctl->numsig);
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+
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+	return has_hnd;
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+}
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+
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 int main(int argc, char **argv)
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 {
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 	struct kill_control ctl = { .numsig = SIGTERM };
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@@ -468,6 +500,8 @@
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 		errno = 0;
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 		ctl.pid = strtol(ctl.arg, &ep, 10);
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 		if (errno == 0 && ep && *ep == '\0' && ctl.arg < ep) {
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+			if (check_signal_handler(&ctl) <= 0)
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+				continue;
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 			if (kill_verbose(&ctl) != 0)
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 				nerrs++;
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 			ct++;
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@@ -482,6 +516,8 @@
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 			proc_processes_filter_by_name(ps, ctl.arg);
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 			while (proc_next_pid(ps, &ctl.pid) == 0) {
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+				if (check_signal_handler(&ctl) <= 0)
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+					continue;
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 				if (kill_verbose(&ctl) != 0)
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 					nerrs++;
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 				ct++;