fallocate: new command

The fallocate(1) utility is used to preallocate blocks to a file.

This can be useful for virtual images, database files, testing, etc.
Normally we'd hope that various tools will start using preallocation
internally, but until then such a utility may be useful, and could be
scripted as well.

The original Eric's version is available at:
http://thread.gmane.org/gmane.linux.utilities.util-linux-ng/2490

This version:
 - checks for fallocate glibc function and kernel syscall
 - does not provide a fallback and does not call posix_fallocate()
 - adds long options
 - uses err.h for errro messages
 - adds NLS support
 - cleanups man page

Co-Author: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

6 files changed, 234 insertions, 0 deletions

diff --git a/AUTHORS b/AUTHORS
index 1aaec44b..b280bb7b 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -31,6 +31,7 @@ AUTHORS (merged projects & commands):
       simpleinit:      Richard Gooch <rgooch@atnf.csiro.au>
       switch_root:     Peter Jones <pjones@redhat.com>
                        Jeremy Katz <katzj@redhat.com>
+      fallocate:       Eric Sandeen <sandeen@redhat.com>
 
 
 CONTRIBUTORS:
diff --git a/configure.ac b/configure.ac
index 9944270e..52985137 100644
--- a/configure.ac
+++ b/configure.ac
@@ -558,6 +558,9 @@ UTIL_CHECK_SYSCALL([ioprio_get],
   [sh*],      [289],
   [x86_64*],  [252])
 
+dnl fallocate could be available as libc function or as syscall only
+UTIL_CHECK_SYSCALL([fallocate])
+AC_CHECK_FUNCS([fallocate])
 
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <time.h>
diff --git a/sys-utils/.gitignore b/sys-utils/.gitignore
index 6f0be710..2cc2deef 100644
--- a/sys-utils/.gitignore
+++ b/sys-utils/.gitignore
@@ -2,6 +2,7 @@ arch
 ctrlaltdel
 cytune
 dmesg
+fallocate
 flock
 i386.8
 ia64.8
diff --git a/sys-utils/Makefile.am b/sys-utils/Makefile.am
index 19ecccca..e6f76290 100644
--- a/sys-utils/Makefile.am
+++ b/sys-utils/Makefile.am
@@ -23,6 +23,11 @@ tunelp_SOURCES = tunelp.c lp.h
 
 info_TEXINFOS = ipc.texi
 
+if HAVE_FALLOCATE
+usrbin_exec_PROGRAMS += fallocate
+dist_man_MANS += fallocate.1
+endif
+
 if HAVE_PIVOT_ROOT
 sbin_PROGRAMS += pivot_root
 dist_man_MANS += pivot_root.8
diff --git a/sys-utils/fallocate.1 b/sys-utils/fallocate.1
new file mode 100644
index 00000000..00e973ce
--- /dev/null
+++ b/sys-utils/fallocate.1
@@ -0,0 +1,51 @@
+.\" -*- nroff -*-
+.TH FALLOCATE 1 "Jul 2009" "Version 1.0"
+.SH NAME
+fallocate \- preallocate space to a file.
+.SH SYNOPSIS
+.B fallocate
+.RB [ \-n ]
+.RB [ \-o
+.IR offset ]
+.B \-l
+.IR length
+.I filename
+.SH DESCRIPTION
+.B fallocate
+is used to preallocate blocks to a file.  For filesystems which support the
+fallocate system call, this is done quickly by allocating blocks and marking
+them as uninitialized, requiring no IO to the data blocks.  This is much faster
+than creating a file by filling it with zeros.
+.PP
+As of the Linux Kernel v2.6.31, the fallocate system call is supported by the
+btrfs, ext4, ocfs2, and xfs filesystems.
+.PP
+The exit code returned by
+.B fallocate
+is 0 on success and 1 on failure.
+.PP
+.SH OPTIONS
+.IP "\fB\-h, \-\-help\fP"
+Print help and exit.
+.IP "\fB\-n, \-\-keep-size\fP"
+Do not modify the apparent length of the file. This may effectively allocate
+blocks past EOF, which can be removed with a truncate.
+.IP "\fB\-o, \-\-offset\fP \fIoffset\fP
+Specifies the beginning offset of the allocation, in bytes.  Suffixes of k, m,
+g, t, p, e may be specified to denote KiB, MiB, GiB, etc.
+.IP "\fB\-l, \-\-length\fP \fIlength\fP
+Specifies the length of the allocation, in bytes.  Suffixes of k, m, g, t, p, e
+may be specified to denote KiB, MiB, GiB, etc.
+.SH AUTHORS
+.nf
+Eric Sandeen <sandeen@redhat.com>
+Karel Zak <kzak@redhat.com>
+.fi
+.SH SEE ALSO
+.BR fallocate (2),
+.BR posix_fallocate (3),
+.BR truncate (1)
+.SH AVAILABILITY
+The fallocate command is part of the util-linux-ng package and is available from
+ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
+
diff --git a/sys-utils/fallocate.c b/sys-utils/fallocate.c
new file mode 100644
index 00000000..66e97649
--- /dev/null
+++ b/sys-utils/fallocate.c
@@ -0,0 +1,173 @@
+/*
+ * fallocate - utility to use the fallocate system call
+ *
+ * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
+ * Written by Eric Sandeen <sandeen@redhat.com>
+ *            Karel Zak <kzak@redhat.com>
+ *
+ * cvtnum routine taken from xfsprogs,
+ * Copyright (c) 2003-2005 Silicon Graphics, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <err.h>
+
+#ifndef HAVE_FALLOCATE
+# include <sys/syscall.h>
+#endif
+
+#include <linux/falloc.h>	/* for FALLOC_FL_* flags */
+
+#include "nls.h"
+
+
+static void __attribute__((__noreturn__)) usage(FILE *out)
+{
+	fprintf(out, _("Usage: %s [options] <filename>\n\nOptions:\n"),
+			program_invocation_short_name);
+
+	fprintf(out, _(
+		" -h, --help          this help\n"
+		" -n, --keep-size     don't modify the length of the file\n"
+		" -o, --offset <num>  offset of the allocation, in bytes\n"
+		" -l, --length <num>  length of the allocation, in bytes\n"));
+
+	fprintf(out, _("\nFor more information see fallocate(1).\n"));
+
+	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
+}
+
+#define EXABYTES(x)     ((x) << 60)
+#define PETABYTES(x)    ((x) << 50)
+#define TERABYTES(x)    ((x) << 40)
+#define GIGABYTES(x)    ((x) << 30)
+#define MEGABYTES(x)    ((x) << 20)
+#define KILOBYTES(x)    ((x) << 10)
+
+static loff_t cvtnum(char *s)
+{
+	loff_t	i;
+	char	*sp;
+
+	i = strtoll(s, &sp, 0);
+	if (i == 0 && sp == s)
+		return -1LL;
+	if (*sp == '\0')
+		return i;
+	if (sp[1] != '\0')
+		return -1LL;
+
+	switch (tolower(*sp)) {
+	case 'k':
+		return KILOBYTES(i);
+	case 'm':
+		return MEGABYTES(i);
+	case 'g':
+		return GIGABYTES(i);
+	case 't':
+		return TERABYTES(i);
+	case 'p':
+		return PETABYTES(i);
+	case 'e':
+		return EXABYTES(i);
+	}
+
+	return -1LL;
+}
+
+int main(int argc, char **argv)
+{
+	char	*fname;
+	int	c;
+	int	error;
+	int	fd;
+	int	mode = 0;
+	loff_t	length = -2LL;
+	loff_t	offset = 0;
+
+	struct option longopts[] = {
+	    { "help",      0, 0, 'h' },
+	    { "keep-size", 0, 0, 'n' },
+	    { "offset",    1, 0, 'o' },
+	    { "lenght",    1, 0, 'l' },
+	    { NULL,        0, 0, 0 }
+	};
+
+	setlocale(LC_ALL, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+
+	while ((c = getopt_long(argc, argv, "hnl:o:", longopts, NULL)) != -1) {
+		switch(c) {
+		case 'h':
+			usage(stdout);
+			break;
+		case 'n':
+			mode |= FALLOC_FL_KEEP_SIZE;
+			break;
+		case 'l':
+			length = cvtnum(optarg);
+			break;
+		case 'o':
+			offset = cvtnum(optarg);
+			break;
+		default:
+			usage(stderr);
+			break;
+		}
+	}
+
+	if (length == -2LL)
+		errx(EXIT_FAILURE, _("no length argument specified"));
+	if (length <= 0)
+		errx(EXIT_FAILURE, _("invalid length value specified"));
+	if (offset < 0)
+		errx(EXIT_FAILURE, _("invalid offset value specified"));
+	if (optind == argc)
+		errx(EXIT_FAILURE, _("no filename specified."));
+
+	fname = argv[optind++];
+
+	fd = open(fname, O_WRONLY|O_CREAT, 0644);
+	if (fd < 0)
+		err(EXIT_FAILURE, _("%s: open failed"), fname);
+
+#ifdef HAVE_FALLOCATE
+	error = fallocate(fd, mode, offset, length);
+#else
+	error = syscall(SYS_fallocate, fd, mode, offset, length);
+#endif
+	/*
+	 * EOPNOTSUPP: The FALLOC_FL_KEEP_SIZE is unsupported
+	 * ENOSYS: The filesystem does not support sys_fallocate
+	 */
+	if (error < 0) {
+		if ((mode & FALLOC_FL_KEEP_SIZE) && errno == EOPNOTSUPP)
+			errx(EXIT_FAILURE,
+				_("keep size mode (-n option) unsupported"));
+		err(EXIT_FAILURE, _("%s: fallocate failed"), fname);
+	}
+
+	close(fd);
+	return EXIT_SUCCESS;
+}