Add support for using versionned symbols

This is a follow-up to jnr/jffi#66 and use the
new API to make it possible to access versioned symbols in a shared
library.

libtest/GNUmakefile

@@ -40,7 +40,7 @@ JFLAGS = -fno-omit-frame-pointer -fno-strict-aliasing
 OFLAGS = -O2 $(JFLAGS)
 WFLAGS = -W -Wall -Wno-unused -Wno-parentheses
 PICFLAGS = -fPIC
-SOFLAGS = -shared -Wl,-O1
+SOFLAGS = -shared -Wl,-O1 -Wl,--version-script,$(SRC_DIR)/libtest.map
 LDFLAGS += $(SOFLAGS)
 
 IFLAGS = -I"$(BUILD_DIR)"

libtest/VersionedSymbols.c

@@ -0,0 +1,14 @@
+int
+old_answer(void)
+{
+    return 41;
+}
+
+int
+new_answer(void)
+{
+    return 42;
+}
+
+__asm__(".symver old_answer,answer@VERS_1.0");
+__asm__(".symver new_answer,answer@@VERS_1.1");

libtest/libtest.map

@@ -0,0 +1,2 @@
+VERS_1.0 {};
+VERS_1.1 {};

src/main/java/jnr/ffi/annotations/Function.java

@@ -0,0 +1,12 @@
+package jnr.ffi.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Function {
+    String value();
+}

src/main/java/jnr/ffi/annotations/Version.java

@@ -0,0 +1,12 @@
+package jnr.ffi.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Version {
+    String value();
+}

src/main/java/jnr/ffi/provider/jffi/AsmLibraryLoader.java

@@ -152,10 +152,25 @@ private <T> T generateInterfaceImpl(final NativeLibrary library, Class<T> interf
                 continue;
             }
 
-            String functionName = functionMapper.mapFunctionName(function.name(), new NativeFunctionMapperContext(library, function.annotations()));
+            String searchName = function.name();
+            String searchVersion = null;
+
+            for (java.lang.annotation.Annotation a : function.annotations()) {
+                if (a.annotationType() == jnr.ffi.annotations.Function.class) {
+                    jnr.ffi.annotations.Function ann = (jnr.ffi.annotations.Function) a;
+                    searchName = ann.value();
+                }
+                if (a.annotationType() == jnr.ffi.annotations.Version.class) {
+                    jnr.ffi.annotations.Version ann = (jnr.ffi.annotations.Version) a;
+                    searchVersion = ann.value();
+                }
+            }
+
+            String functionName = functionMapper.mapFunctionName(searchName, new NativeFunctionMapperContext(library, function.annotations()));
 
             try {
-                long functionAddress = library.findSymbolAddress(functionName);
+                System.out.println(searchName + " " + searchVersion);
+                long functionAddress = library.findSymbolAddress(functionName, searchVersion);
 
                 FromNativeContext resultContext = new MethodResultContext(runtime, function.getMethod());
                 SignatureType signatureType = DefaultSignatureType.create(function.getMethod().getReturnType(), resultContext);

src/main/java/jnr/ffi/provider/jffi/NativeLibrary.java

@@ -46,8 +46,17 @@ private String locateLibrary(String libraryName) {
     }
 
     long getSymbolAddress(String name) {
+        return getSymbolAddress(name, null);
+    }
+
+    long getSymbolAddress(String name, String version) {
         for (com.kenai.jffi.Library l : getNativeLibraries()) {
-            long address = l.getSymbolAddress(name);
+            long address;
+            if (version != null)
+                address = l.getSymbolAddressWithVersion(name, version);
+            else
+                address = l.getSymbolAddress(name);
+
             if (address != 0) {
                 return address;
             }
@@ -56,7 +65,11 @@ long getSymbolAddress(String name) {
     }
 
     long findSymbolAddress(String name) {
-        long address = getSymbolAddress(name);
+        return findSymbolAddress(name, null);
+    }
+
+    long findSymbolAddress(String name, String version) {
+        long address = getSymbolAddress(name, version);
         if (address == 0) {
             throw new SymbolNotFoundError(com.kenai.jffi.Library.getLastError());
         }

src/test/java/jnr/ffi/VersionTest.java

@@ -0,0 +1,70 @@
+package jnr.ffi;
+
+import jnr.ffi.annotations.Function;
+import jnr.ffi.annotations.Version;
+
+import jnr.ffi.types.*;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+
+public class VersionTest {
+    public VersionTest() {
+    }
+
+    public static interface TestLib {
+        public int answer();
+        public int old_answer();
+        public int new_answer();
+
+        @Function("answer")
+        @Version("VERS_1.0")
+        public int answer_1_0();
+
+        @Function("answer")
+        @Version("VERS_1.1")
+        public int answer_1_1();
+    }
+    static TestLib testlib;
+
+    @BeforeClass
+    public static void setUpClass() throws Exception {
+        testlib = TstUtil.loadTestLib(TestLib.class);
+    }
+
+    @AfterClass
+    public static void tearDownClass() throws Exception {
+    }
+
+    @Test
+    public void testAnswer() {
+        int res = testlib.answer();
+        assertEquals(42, res);
+    }
+
+    @Test
+    public void testOldAnswer() {
+        int res = testlib.old_answer();
+        assertEquals(41, res);
+    }
+
+    @Test
+    public void testNewAnswer() {
+        int res = testlib.new_answer();
+        assertEquals(42, res);
+    }
+
+    @Test
+    public void testAnswer_1_0() {
+        int res = testlib.answer_1_0();
+        assertEquals(41, res);
+    }
+
+    @Test
+    public void testAnswer_1_1() {
+        int res = testlib.answer_1_1();
+        assertEquals(42, res);
+    }
+}