Add swapon(8)

No manpage yet.

Makefile

@@ -24,7 +24,8 @@ SRC += \
 	mkswap.c            \
 	reboot.c            \
 	rmmod.c             \
-	swapoff.c
+	swapoff.c           \
+	swapon.c
 endif
 
 OBJ = $(SRC:.c=.o) $(LIB)

swapon.c

@@ -0,0 +1,41 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/swap.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-d] swapfile\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int i;
+	int ret = 0;
+	int flags = 0;
+
+	ARGBEGIN {
+	case 'd':
+		flags |= SWAP_FLAG_DISCARD;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc < 1)
+		usage();
+
+	for (i = 0; i < argc; i++) {
+		ret = swapon(argv[i], flags);
+		if (ret < 0) {
+			fprintf(stderr, "swapon %s: %s\n",
+				argv[i], strerror(errno));
+			ret = 1;
+		}
+	}
+	return ret;
+}