[libjna-java] 02/03: Added a default implementation of Structure.getFieldOrder() to preserve the compatibility with JNA < 3.5.0

[Emmanuel Bourg]

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ebourg-guest pushed a commit to branch master
in repository libjna-java.

commit 2bed85a971af3832d923214e47892a1c48b3df3e
Author: Emmanuel Bourg <ebourg at apache.org>
Date:   Thu Oct 16 00:23:02 2014 +0200

    Added a default implementation of Structure.getFieldOrder() to preserve the compatibility with JNA < 3.5.0
---
 debian/changelog                                   |  2 +
 .../12-structure-backward-compatibility.patch      | 76 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 79 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index bf1198f..9f67fa7 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -14,6 +14,8 @@ libjna-java (4.1.0-1) UNRELEASED; urgency=low
   * Removed 08-multiarch-support.patch (merged upstream since jna 3.5.0)
   * Removed 02-builddir.patch (merged upstream since 4.0.0)
   * Removed 05-support-gnu-kfreebsd.patch (merged upstream since 4.0.0)
+  * Added a default implementation of Structure.getFieldOrder() to preserve
+    the compatibility with JNA < 3.5.0
   * Moved libjnidispatch.so into its own new arch any libjna-jni package
   * Install libjnidispatch.so in a multiarch path
   * Install the Maven artifacts for the platform jar (Closes: #743732)
diff --git a/debian/patches/12-structure-backward-compatibility.patch b/debian/patches/12-structure-backward-compatibility.patch
new file mode 100644
index 0000000..559e2f5
--- /dev/null
+++ b/debian/patches/12-structure-backward-compatibility.patch
@@ -0,0 +1,76 @@
+Description: Provide a default implementation of the abstract Structure.getFieldOrder()
+ method to preserve the compatibility with JNA < 3.5.0. The implementation is derived
+ from the JNA 3.4.2 code.
+Author: Emmanuel Bourg <ebourg at apache.org>
+Forwarded: not-needed
+--- a/src/com/sun/jna/Structure.java
++++ b/src/com/sun/jna/Structure.java
+@@ -106,6 +106,34 @@
+      */
+     public interface ByReference { }
+ 
++    private static class MemberOrder {
++        private static final String[] FIELDS = { "first", "second", "middle", "penultimate", "last" };
++        public int first;
++        public int second;
++        public int middle;
++        public int penultimate;
++        public int last;
++    }
++
++    private static final boolean REVERSE_FIELDS;
++    private static final boolean REQUIRES_FIELD_ORDER;
++
++    static {
++        // Check for predictable field order; IBM and JRockit store fields in
++        // reverse order; Excelsior JET requires explicit order
++        Field[] fields = MemberOrder.class.getFields();
++        List names = new ArrayList();
++        for (int i=0; i < fields.length; i++) {
++            names.add(fields[i].getName());
++        }
++        List expected = Arrays.asList(MemberOrder.FIELDS);
++        List reversed = new ArrayList(expected);
++        Collections.reverse(reversed);
++
++        REVERSE_FIELDS = names.equals(reversed);
++        REQUIRES_FIELD_ORDER = !(names.equals(expected) || REVERSE_FIELDS);
++    }
++
+     /** Use the platform default alignment. */
+     public static final int ALIGN_DEFAULT = 0;
+     /** No alignment, place all fields on nearest 1-byte boundary */
+@@ -831,7 +859,32 @@
+      * field order as returned by {@link Class#getFields()} is not
+      * guaranteed to be predictable.
+      */
+-    protected abstract List getFieldOrder();
++    protected List getFieldOrder() {
++        if (REQUIRES_FIELD_ORDER) {
++            throw new Error("This VM does not store fields in a predictable order; you must implement Structure.getFieldOrder on " + getClass() + " to explicitly indicate the field order: " + System.getProperty("java.vendor") + ", " + System.getProperty("java.version"));
++        }
++
++        return getFieldNames();
++    }
++
++    private List<String> getFieldNames() {
++        List<String> names = new ArrayList<String>();
++        for (Class cls = getClass(); !cls.equals(Structure.class); cls = cls.getSuperclass()) {
++            List<String> fields = new ArrayList<String>();
++            for (Field field : cls.getDeclaredFields()) {
++                int modifiers = field.getModifiers();
++                if (Modifier.isStatic(modifiers) || !Modifier.isPublic(modifiers)) {
++                    continue;
++                }
++                fields.add(field.getName());
++            }
++            if (REVERSE_FIELDS) {
++                Collections.reverse(fields);
++            }
++            names.addAll(0, fields);
++        }
++        return names;
++    }
+ 
+     /**
+      * Force a compile-time error on the old method of field definition
diff --git a/debian/patches/series b/debian/patches/series
index 3e21bda..705cad6 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -4,3 +4,4 @@
 06-remove-gjdoc-inexistent-options.patch
 09-javadoc.patch
 10-disable-full-jar.patch
+12-structure-backward-compatibility.patch

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