Recent changes to events (commit 8a29ffcf) resulted in new compile
failures on some targets (such as ARM OMAP5):
conf/domain_event.c: In function 'virDomainEventDispatchDefaultFunc':
conf/domain_event.c:1198:30: error: cast increases required alignment of
target type [-Werror=cast-align]
conf/domain_event.c:1314:34: error: cast increases required alignment of
target type [-Werror=cast-align]
cc1: all warnings being treated as errors
The error is due to alignment; the base class is merely aligned
to the worst of 'int' and 'void*', while the child class must
be aligned to a 'long long'. The solution is to include a
'long long' (and for good measure, a function pointer) in the
base class to ensure correct alignment regardless of what a
child class may add, but to wrap the inclusion in a union so
as to not incur any wasted space. On a typical x86_64 platform,
the base class remains 16 bytes; on i686, the base class remains
12 bytes; and on the impacted ARM platform, the base class grows
from 12 bytes to 16 bytes due to the increase of alignment from
4 to 8 bytes.
Reported by Michele Paolino and others.
* src/util/virobject.h (_virObject): Use a union to ensure that
subclasses never have stricter alignment than the parent.
* src/util/virobject.c (virObjectNew, virObjectUnref)
(virObjectRef): Adjust clients.
* src/libvirt.c (virConnectRef, virDomainRef, virNetworkRef)
(virInterfaceRef, virStoragePoolRef, virStorageVolRef)
(virNodeDeviceRef, virSecretRef, virStreamRef, virNWFilterRef)
(virDomainSnapshotRef): Likewise.
* src/qemu/qemu_monitor.c (qemuMonitorOpenInternal)
(qemuMonitorClose): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
The current way virObject instances are allocated using
VIR_ALLOC_N causes alignment warnings
util/virobject.c: In function 'virObjectNew':
util/virobject.c:195:11: error: cast increases required alignment of target type [-Werror=cast-align]
Changing to use VIR_ALLOC_VAR will avoid the need todo
the casts entirely.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
When building with static analysis enabled, we turn on attribute
nonnull checking. However, this caused the build to fail with:
../../src/util/virobject.c: In function 'virObjectOnceInit':
../../src/util/virobject.c:55:40: error: null argument where non-null required (argument 1) [-Werror=nonnull]
Creation of the virObject class is the one instance where the
parent class is allowed to be NULL. Making things conditional
will let us keep static analysis checking for all other .c file
callers, without breaking the build on this one exception.
* src/util/virobject.c: Define witness.
* src/util/virobject.h (virClassNew): Use it to force most callers
to pass non-null parameter.
A great many virObject instances require a mutex, so introduce
a convenient class for this which provides a mutex. This avoids
repeating the tedious init/destroy code
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Currently all classes must directly inherit from virObject.
This allows for arbitrarily deep hierarchy. There's not much
to this aside from chaining up the 'dispose' handlers from
each class & providing APIs to check types.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
https://www.gnu.org/licenses/gpl-howto.html recommends that
the 'If not, see <url>.' phrase be a separate sentence.
* tests/securityselinuxhelper.c: Remove doubled line.
* tests/securityselinuxtest.c: Likewise.
* globally: s/; If/. If/
This introduces a fairly basic reference counted virObject type
and an associated virClass type, that use atomic operations for
ref counting.
In a global initializer (recommended to be invoked using the
virOnceInit API), a virClass type must be allocated for each
object type. This requires a class name, a "dispose" callback
which will be invoked to free memory associated with the object's
fields, and the size in bytes of the object struct.
eg,
virClassPtr connclass = virClassNew("virConnect",
sizeof(virConnect),
virConnectDispose);
The struct for the object, must include 'virObject' as its
first member
eg
struct _virConnect {
virObject object;
virURIPtr uri;
};
The 'dispose' callback is only responsible for freeing
fields in the object, not the object itself. eg a suitable
impl for the above struct would be
void virConnectDispose(void *obj) {
virConnectPtr conn = obj;
virURIFree(conn->uri);
}
There is no need to reset fields to 'NULL' or '0' in the
dispose callback, since the entire object will be memset
to 0, and the klass pointer & magic integer fields will
be poisoned with 0xDEADBEEF before being free()d
When creating an instance of an object, one needs simply
pass the virClassPtr eg
virConnectPtr conn = virObjectNew(connclass);
if (!conn)
return NULL;
conn->uri = virURIParse("foo:///bar")
Object references can be manipulated with
virObjectRef(conn)
virObjectUnref(conn)
The latter returns a true value, if the object has been
freed (ie its ref count hit zero)
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
