Calling block_resize on a Libvirt::Domain object leads to a TypeError. The reason seems to be that ruby-libvirt tries to convert the size instead of the disk to a string to pass as the disk parameter. --- ext/libvirt/domain.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/ext/libvirt/domain.c b/ext/libvirt/domain.c index 7812450..aff1842 100644 --- a/ext/libvirt/domain.c +++ b/ext/libvirt/domain.c @@ -2882,7 +2882,7 @@ static VALUE libvirt_domain_block_resize(int argc, VALUE *argv, VALUE d) ruby_libvirt_generate_call_nil(virDomainBlockResize, ruby_libvirt_connect_get(d), ruby_libvirt_domain_get(d), - StringValueCStr(size), NUM2ULL(size), + StringValueCStr(disk), NUM2ULL(size), ruby_libvirt_value_to_uint(flags)); } #endif -- 2.7.4