Add blkdiscard(8)

Makefile

@@ -37,6 +37,7 @@ LIBUTILSRC = \
 LIB = $(LIBUTIL)
 
 BIN = \
+	blkdiscard        \
 	chvt              \
 	clear             \
 	ctrlaltdel        \

blkdiscard.8

@@ -0,0 +1,12 @@
+.Dd July 2, 2018
+.Dt BLKDISCARD 8
+.Os ubase
+.Sh NAME
+.Nm blkdiscard
+.Nd discard sectors on a device
+.Sh SYNOPSIS
+.Nm
+.Ar device
+.Sh DESCRIPTION
+.Nm
+is used to discard all device sectors on solid-state devices.

blkdiscard.c

@@ -0,0 +1,48 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/ioctl.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <fcntl.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#include "util.h"
+
+#define OFFSET_IDX	0
+#define LENGTH_IDX	1
+
+#define BLKDISCARD	_IO(0x12, 119)
+
+static void
+usage(void)
+{
+	eprintf("usage: %s device\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	uint64_t range[2];
+	int fd;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND
+
+	if (argc != 1)
+		usage();
+
+	fd = open(argv[0], O_RDWR);
+	if (fd < 0)
+		eprintf("open: %s:", argv[0]);
+	range[OFFSET_IDX] = 0;
+	if (ioctl(fd, BLKGETSIZE64, &range[LENGTH_IDX]) < 0)
+		eprintf("BLKGETSIZE64: %s:", argv[0]);
+	if (ioctl(fd, BLKDISCARD, range) < 0)
+		eprintf("BLKDISCARD: %s:", argv[0]);
+	close(fd);
+	return 0;
+}