Allow overriding dd and blockdev commands

Let the user provide their own dd and/or blockdev commands,
if desired.
Signed-off-by: Dimitris Aragiorgis <dimitris.aragiorgis@gmail.com>

snf-image-host/common.sh.in

-# Copyright (C) 2011-2016 GRNET S.A.
+# Copyright (C) 2011-2016 GRNET S.A. and individual contributors
 # Copyright (C) 2007, 2008, 2009 Google Inc.
 #
 # This program is free software; you can redistribute it and/or modify
@@ -29,6 +29,8 @@ TAR="tar"
 DATE="date -u" # Time in UTC
 KVM="kvm"
 MD5SUM="md5sum"
+BLOCKDEV="blockdev"
+DD="dd"
 
 # Temporary use stderr as monitoring file descriptor.
 # `create' will overwrite this
@@ -227,7 +229,7 @@ create_floppy() {
     target=$(mktemp -d)
     add_cleanup rmdir "$target"
 
-    dd bs=512 count=2880 if=/dev/zero of="$img"
+    $DD bs=512 count=2880 if=/dev/zero of="$img"
     mkfs.ext2 -F "$img" > /dev/null
     mount "$img" "$target" -o loop
 

snf-image-host/create

@@ -175,9 +175,9 @@ if [ "$BACKEND_TYPE" = "local" ]; then
     # Deploying an image file on a target block device is a streaming copy
     # operation. Enable the direct I/O flag on the output fd to avoid polluting
     # the host cache with useless data.
-    $monitor dd bs=4M if="$image_file" of="$target" oflag=direct iflag=fullblock
+    $monitor $DD bs=4M if="$image_file" of="$target" oflag=direct iflag=fullblock
 else
-    $image_cmd | $monitor dd bs=4M of="$target" oflag=direct iflag=fullblock
+    $image_cmd | $monitor $DD bs=4M of="$target" oflag=direct iflag=fullblock
 fi
 report_info "Image copy finished."
 

snf-image-host/defaults.in

@@ -142,3 +142,5 @@
 # TIMEOUT="timeout"
 # CURL="curl"
 # TAR="tar"
+# BLOCKDEV="blockdev"
+# DD="dd"

snf-image-host/export

 #!/bin/bash
 
-# Copyright (C) 2012 GRNET S.A.
+# Copyright (C) 2012-2016 GRNET S.A. and individual contributors
 #
 # 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
@@ -35,10 +35,10 @@ fi
 # Export disk's predicted size to Ganeti.
 # Used to provide a time estimate of the export process to the user.
 if [ -n "$EXP_SIZE_FD" ]; then
-    blockdev --getsize64 "$blockdev" >&$EXP_SIZE_FD
+    $BLOCKDEV --getsize64 "$blockdev" >&$EXP_SIZE_FD
 fi
 
-dd if="$blockdev" bs=4M
+$DD if="$blockdev" bs=4M
 
 # Execute cleanups
 cleanup

snf-image-host/import

 #!/bin/bash
 
-# Copyright (C) 2012 GRNET S.A.
+# Copyright (C) 2012-2016 GRNET S.A. and individual contributors
 #
 # 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
@@ -32,7 +32,7 @@ if [ ! -b "$blockdev" ]; then
     add_cleanup $LOSETUP -d "$blockdev"
 fi
 
-dd of="$blockdev" bs=4M
+$DD of="$blockdev" bs=4M
 
 # Execute cleanups
 cleanup