Re: [Libguestfs] [PATCH] Target::LibVirt: Don't truncate a volume when opening it

On Wed, Apr 07, 2010 at 12:05:37PM +0100, Matthew Booth wrote: > perl's '>' open mode truncates by default, and will create a new file if > necessary. We don't want to truncate an existing volume when writing to it, and > it's an error if the volume doesn't already exist. Use sysopen to be explicit > about this. > --- > lib/Sys/VirtV2V/Target/LibVirt.pm | 6 +++++- > 1 files changed, 5 insertions(+), 1 deletions(-) > > diff --git a/lib/Sys/VirtV2V/Target/LibVirt.pm b/lib/Sys/VirtV2V/Target/LibVirt.pm > index c8802ac..99a1ad2 100644 > --- a/lib/Sys/VirtV2V/Target/LibVirt.pm > +++ b/lib/Sys/VirtV2V/Target/LibVirt.pm > @@ -20,6 +20,8 @@ use warnings; > > package Sys::VirtV2V::Target::LibVirt::Vol; > > +use POSIX; > + > use Sys::VirtV2V::UserMessage qw(user_message); > > sub _new > @@ -106,7 +108,9 @@ sub open > my $self = shift; > > my $path = $self->get_path(); > - open(my $fd, '>', $path) > + > + # We want to open the existing volume without truncating it > + sysopen(my $fd, $path, O_WRONLY) NB There's no need to switch to sysopen. You can use '>>' instead of '>' if you want to append instead of truncate