Re: [libvirt] [TCK PATCH] block devices: allow specification of size for safety
On 05/05/2010 12:54 PM, Jim Meyering wrote:
> + if (!defined $device) {
> + $device = $self->config("host_block_devices/[$devindex]", undef);
> + }
This can be equivalently (idiomatically) written as:
$device ||= $self->config("host_block_devices/[$devindex]", undef);
Thanks for the tip.
> + if ($size) {
> + sysopen(BLK, "$device", O_RDONLY) or return undef;
> + return undef unless sysseek(BLK, 0, SEEK_END) == $size * 1024;
> + close(BLK);
> + }
(Note no need for double quotes around $device;
Leaving parens off of some built-ins like "close" is a personal
preference (less syntax is better), but obviously keeping in sync
with the prevailing style is more important)
This is similar, but doesn't leave BLK open upon failure or size mismatch:
Aargh. I noticed that too, and even have it in my editor, but I hadn't
hit save before I did 'git commit'. But your alternative
if ($size) {
my $match = (sysopen (BLK, $device, O_RDONLY)
&& sysseek (BLK, 0, SEEK_END) == $size * 1024);
close BLK;
$match or return undef;
}
is even shorter that what 'git diff' says was still in my editor:
diff --git i/lib/Sys/Virt/TCK.pm w/lib/Sys/Virt/TCK.pm
index fc325a3..1fcfdf0 100644
--- i/lib/Sys/Virt/TCK.pm
+++ w/lib/Sys/Virt/TCK.pm
@@ -835,15 +835,16 @@ sub get_host_block_device {
my $devindex = @_ ? shift : 0;
my $device = $self->config("host_block_devices/[$devindex]/path",
undef);
- my $size = $self->config("host_block_devices/[$devindex]/size", 0);
+ my $blocks = $self->config("host_block_devices/[$devindex]/size", 0);
if (!defined $device) {
$device = $self->config("host_block_devices/[$devindex]", undef);
}
- if ($size) {
+ if ($blocks) {
sysopen(BLK, "$device", O_RDONLY) or return undef;
- return undef unless sysseek(BLK, 0, SEEK_END) == $size * 1024;
+ my $size = sysseek(BLK, 0, SEEK_END);
close(BLK);
+ return undef unless $size == $blocks * 1024;
}
return $device;
}
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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