Add truncate(1)

Makefile

@@ -34,6 +34,7 @@ SRC = \
 	stat.c              \
 	swapoff.c           \
 	swapon.c            \
+	truncate.c          \
 	umount.c            \
 	unshare.c
 

truncate.c

@@ -0,0 +1,46 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-c] -s size file...\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int cflag = 0, sflag = 0;
+	int fd, i;
+	long size;
+
+	ARGBEGIN {
+	case 's':
+		sflag = 1;
+		size = estrtol(EARGF(usage()), 10);
+		break;
+	case 'c':
+		cflag = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc < 1 || !sflag)
+		usage();
+
+	for (i = 0; i < argc; i++) {
+		fd = open(argv[i], O_WRONLY | (cflag ? 0 : O_CREAT), 0644);
+		if (fd < 0)
+			eprintf("open %s:", argv[i]);
+		if (ftruncate(fd, size) < 0)
+			eprintf("ftruncate: %s:", argv[i]);
+		close(fd);
+	}
+	return 0;
+}