Add initial version of killall5(8)

Makefile

@@ -29,6 +29,7 @@ SRC = \
 	halt.c              \
 	id.c                \
 	insmod.c            \
+	killall5.c          \
 	lsmod.c             \
 	lsusb.c             \
 	mknod.c             \

killall5.c

@@ -0,0 +1,78 @@
+/* See LICENSE file for copyright and license details. */
+#include <dirent.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <unistd.h>
+#include "proc.h"
+#include "util.h"
+
+struct {
+	const char *name;
+	int sig;
+} sigs[] = {
+#define SIG(n) { #n, SIG##n }
+	SIG(ABRT), SIG(ALRM), SIG(BUS),  SIG(CHLD), SIG(CONT), SIG(FPE),  SIG(HUP),
+	SIG(ILL),  SIG(INT),  SIG(KILL), SIG(PIPE), SIG(QUIT), SIG(SEGV), SIG(STOP),
+	SIG(TERM), SIG(TSTP), SIG(TTIN), SIG(TTOU), SIG(USR1), SIG(USR2), SIG(URG),
+#undef SIG
+};
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-s signal]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	DIR *dp;
+	struct dirent *entry;
+	char *end, *v;
+	int sig = SIGTERM;
+	pid_t pid;
+	size_t i;
+
+	ARGBEGIN {
+	case 's':
+		v = EARGF(usage());
+		sig = strtol(v, &end, 0);
+		if(*end == '\0')
+			break;
+		for(i = 0; i < LEN(sigs); i++) {
+			if(strcasecmp(v, sigs[i].name) == 0) {
+				sig = sigs[i].sig;
+				break;
+			}
+		}
+		if(i == LEN(sigs))
+			eprintf("%s: unknown signal\n", v);
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (sig != SIGSTOP && sig != SIGCONT)
+		kill(-1, SIGSTOP);
+
+	if (!(dp = opendir("/proc")))
+		eprintf("opendir /proc:");
+	while ((entry = readdir(dp))) {
+		if (!pidfile(entry->d_name))
+			continue;
+		pid = estrtol(entry->d_name, 10);
+		if (pid == 1 || pid == getpid() ||
+		    getsid(pid) == getsid(0) || getsid(pid) == 0)
+			continue;
+		kill(pid, sig);
+	}
+	closedir(dp);
+
+	if (sig != SIGSTOP && sig != SIGCONT)
+		kill(-1, SIGCONT);
+
+	return EXIT_SUCCESS;
+}