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authorH. Peter Anvin <hpa@zytor.com>2010-02-01 15:41:43 -0800
committerH. Peter Anvin <hpa@zytor.com>2010-02-01 15:41:43 -0800
commit1e96e9cc1c3549c86dbf4e7caf880477e16e93e0 (patch)
tree7993bfc3c81f4253247e07587d61399466c69880 /utils
parentb8a9a8c9c928fe76feb2ed0cd0eee6275623fa5a (diff)
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mkdiskimage: add option -s to make a sparse imagesyslinux-3.85-pre4
It is often fine to have a sparse file for the output image, so add an -s option to generate a sparse image. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'utils')
-rw-r--r--utils/mkdiskimage.in16
1 files changed, 10 insertions, 6 deletions
diff --git a/utils/mkdiskimage.in b/utils/mkdiskimage.in
index 9231fa21..533193a1 100644
--- a/utils/mkdiskimage.in
+++ b/utils/mkdiskimage.in
@@ -2,7 +2,7 @@
## -----------------------------------------------------------------------
##
## Copyright 2002-2008 H. Peter Anvin - All Rights Reserved
-## Copyright 2009 Intel Corporation; author: H. Peter Anvin
+## Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
##
## 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
@@ -144,6 +144,7 @@ if ( $file eq '' || $c < 1 || $h < 1 || $h > 256 || $s < 1 || $s > 63 ) {
print STDERR " -z use zipdisk geometry (h=64 s=32)\n";
print STDERR " -4 use partition entry 4 (standard for zipdisks)\n";
print STDERR " -i specify the MBR ID\n";
+ print STDERR " -s output a sparse file (don't allocate all blocks)\n";
exit 1;
}
@@ -216,13 +217,16 @@ print OUTPUT "\x55\xaa";
$totalsize = $c*$h*$s;
$tracks = $c*$h;
-$track = "\0" x (512*$s);
+# If -s is given, try to simply use truncate...
+unless ($opt{'s'} && truncate(OUTPUT, $totalsize)) {
+ $track = "\0" x (512*$s);
-# Print fractional track
-print OUTPUT "\0" x (512 * ($s-1));
+ # Print fractional track
+ print OUTPUT "\0" x (512 * ($s-1));
-for ( $i = 1 ; $i < $tracks ; $i++ ) {
- print OUTPUT $track;
+ for ( $i = 1 ; $i < $tracks ; $i++ ) {
+ print OUTPUT $track;
+ }
}
# Print mtools temp file