Re: [libvirt] [PATCH] [libvirt-java] Fix Array IndexOutOfBoundsException for unknown error codes
On 08/01/2012 08:11 AM, Claudio Bley wrote:
At Mon, 23 Jul 2012 14:56:55 -0600,
> the old version crashed, and your version leaves code as null
(which is
> a strict improvement, but might cause its own NullPointer issue later
> on). Having an else branch that sticks in a placeholder would be nicer
> to end clients to at least recognize that they are talking to a newer
> server, without crashing.
Please have look at the following patch.
-- >8 --
Subject: [PATCH] Fix IndexOutOfBoundsException for unknown error
number/domain/level codes.
Remove default constructor because it does not init the object properly.
Add a special *_UNKNOWN enum value to each enum which is used when the
given enum code is out of bounds.
+ /**
+ * Map an integer to an enum value.
+ *
+ * @return when {@code n < values.length} return n-th item of
+ * {@code values}, otherwise the last item of array
+ * {@code values}.
+ */
+ private static final <T extends Enum<T>> T wrapToEnum(final int n, final
T[] values) {
Wow, Java has changed since I last programmed in it (I haven't
programmed Java since 1.4 when 'assert' was added, although I was at
least following the development of Java 1.5 at the time enough to
understand this syntax - I guess that would be 8 or so years ago?).
@@ -71,7 +90,13 @@ public class Error implements Serializable {
/**
* An error
*/
- VIR_ERR_ERROR
+ VIR_ERR_ERROR,
+
+ VIR_ERR_UNKNOWN; /* must be the last entry! */
Is this...
+
+ protected static final ErrorLevel wrap(int value) {
+ return wrapToEnum(value, values());
+ }
}
public static enum ErrorNumber {
@@ -161,6 +186,11 @@ public class Error implements Serializable {
VIR_ERR_MIGRATE_UNSAFE, /* Migration is not safe */
VIR_ERR_OVERFLOW, /* integer overflow */
VIR_ERR_BLOCK_COPY_ACTIVE, /* action prevented by block copy job */
+ VIR_ERR_UNKNOWN; /* unknown error (must be the last entry!) */
...and this common use of a name among two different enums going to bite
us? If so, I'd recommend munging the names, maybe:
VIR_ERR_LEVEL_UNKNOWN vs. VIR_ERR_NUMBER_UNKNOWN.
public Error(virError vError) {
- code = ErrorNumber.values()[vError.code];
- domain = ErrorDomain.values()[vError.domain];
- level = ErrorLevel.values()[vError.level];
+ code = code.wrap(vError.code);
+ domain = domain.wrap(vError.domain);
+ level = level.wrap(vError.level);
Slick. Depending on your answer to my question on whether a rename
makes sense, I don't mind pushing this or a slightly different v2. When
using 'git send-email', it helps to use '--subject-prefix="libvirt-java
PATCHv2" ' for the repost to make it obvious that it is a revision of an
earlier post.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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