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|
use strict;
use POSIX ();
# Example Perl plugin.
#
# This example can be freely used for any purpose.
# Run it from the build directory like this:
#
# ./nbdkit -f -v perl ./plugins/perl/example.pl test1=foo test2=bar
#
# Or run it after installing nbdkit like this:
#
# nbdkit -f -v perl ./plugins/perl/example.pl test1=foo test2=bar
#
# The -f -v arguments are optional. They cause the server to stay in
# the foreground and print debugging, which is useful when testing.
#
# You can connect to the server using guestfish or qemu, eg:
#
# guestfish --format=raw -a nbd://localhost
# ><fs> run
# ><fs> part-disk /dev/sda mbr
# ><fs> mkfs ext2 /dev/sda1
# ><fs> list-filesystems
# ><fs> mount /dev/sda1 /
# ><fs> [etc]
# This is the string used to store the emulated disk (initially all
# zero bytes). There is one disk per nbdkit instance, so if you
# reconnect to the same server you should see the same disk. You
# could also put this into the handle, so there would be a fresh disk
# per handle.
my $disk = "\0" x (1024*1024);
# This just prints the extra command line parameters, but real plugins
# should parse them and reject any unknown parameters.
sub config
{
my $key = shift;
my $value = shift;
print "$0: ignored parameter $key=$value\n";
}
sub open
{
my $readonly = shift;
printf ("$0: open: readonly=%d\n", $readonly);
# You can return any Perl value from open, and the same Perl value
# will be passed as the first arg to the other callbacks [in the
# client connected phase]. In most cases it's convenient to use a
# hashref.
my $h = { readonly => $readonly };
return $h;
}
sub get_size
{
my $h = shift;
return length ($disk);
}
sub pread
{
my $h = shift;
my $count = shift;
my $offset = shift;
my $flags = shift;
return substr ($disk, $offset, $count);
}
sub pwrite
{
my $h = shift;
my $buf = shift;
my $count = length ($buf);
my $offset = shift;
my $flags = shift;
substr ($disk, $offset, $count) = $buf;
}
sub zero
{
my $h = shift;
my $count = shift;
my $offset = shift;
my $flags = shift;
if ($flags & $Nbdkit::FLAG_MAY_TRIM) {
substr ($disk, $offset, $count) = "\0" x $count;
} else {
Nbdkit::set_error(POSIX::EOPNOTSUPP);
die "fall back to pwrite";
}
}
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