Add fallocate(1)

Makefile

@@ -19,6 +19,7 @@ SRC = \
 	clear.c             \
 	df.c                \
 	dmesg.c             \
+	fallocate.c         \
 	free.c              \
 	halt.c              \
 	insmod.c            \

fallocate.c

@@ -0,0 +1,41 @@
+/* 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 -l length file\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int fd;
+	long size;
+
+	ARGBEGIN {
+	case 'l':
+		size = estrtol(EARGF(usage()), 10);
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc != 1 || !size)
+		usage();
+
+	fd = open(argv[0], O_RDWR | O_CREAT, 0644);
+	if (fd < 0)
+		eprintf("open %s:", argv[0]);
+
+	if (posix_fallocate(fd, 0, size) < 0)
+		eprintf("posix_fallocate:");
+
+	close(fd);
+	return 0;
+}