Add support for dlvsym(3)

Author: smortex

libtest/GNUmakefile

@@ -47,7 +47,7 @@ JFLAGS = -fno-omit-frame-pointer -fno-strict-aliasing
 OFLAGS = -O2 $(JFLAGS)
 WFLAGS = -W -Werror -Wall -Wno-unused -Wno-unused-parameter -Wno-parentheses
 PICFLAGS = -fPIC
-SOFLAGS = -shared -Wl,-O1
+SOFLAGS = -shared -Wl,-O1 -Wl,--version-script,$(SRC_DIR)/libtest.map
 LDFLAGS += $(SOFLAGS)
 
 IFLAGS = -I"$(BUILD_DIR)"
@@ -127,17 +127,17 @@ ifeq ($(OS), solaris)
   CC = gcc
   CFLAGS += -std=c99
   LD = /usr/ccs/bin/ld
-  SOFLAGS = -shared -static-libgcc 
+  SOFLAGS = -shared -static-libgcc -Wl,--version-script,$(SRC_DIR)/libtest.map
 endif
 
 ifeq ($(OS), aix)
   LIBEXT = a
-  SOFLAGS = -shared -static-libgcc
+  SOFLAGS = -shared -static-libgcc -Wl,--version-script,$(SRC_DIR)/libtest.map
   PICFLAGS += -pthread
 endif
 
 ifneq ($(findstring bsd, $(OS)),)
-  SOFLAGS = -shared -static-libgcc
+  SOFLAGS = -shared -static-libgcc -Wl,--version-script,$(SRC_DIR)/libtest.map
   CFLAGS += -pthread
   LDFLAGS += -pthread
 endif

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/com/kenai/jffi/Foreign.java

@@ -290,6 +290,16 @@ static boolean isMemoryProtectionEnabled() {
      */
     static native long dlsym(long handle, String name);
 
+    /**
+     * Locates the memory address of the specified version of a dynamic library symbol.
+     *
+     * @param handle A dynamic library handle obtained from {@link #dlopen}
+     * @param name The name of the symbol.
+     * @param version The version of the symbol.
+     * @return The address where the symbol in loaded in memory.
+     */
+    static native long dlvsym(long handle, String name, String version);
+
     /**
      * Gets the last error raised by {@link #dlopen} or {@link #dlsym}
      *

src/main/java/com/kenai/jffi/Library.java

@@ -182,6 +182,23 @@ public final long getSymbolAddress(String name) {
         }
     }
 
+    /**
+     * Gets the address of a symbol within the <tt>Library</tt>.
+     * 
+     * @param name The name of the symbol to locate.
+     * @param version The version of the symbol to locate.
+     * @return The address of the symbol within the current address space.
+     */
+    public final long getSymbolAddressWithVersion(String name, String version) {
+        try {
+            return foreign.dlvsym(handle, name, version);
+
+        } catch (UnsatisfiedLinkError ex) {
+            lastError.set(foreign.dlerror());
+            return 0;
+        }
+    }
+    
     /**
      * Gets the current error string from dlopen/LoadLibrary.
      *

src/test/java/com/kenai/jffi/UnitHelper.java

@@ -112,6 +112,13 @@ public static Address findSymbol(String name) {
         }
         return new Address(address);
     }
+    public static Address findSymbolWithVersion(String name, String version) {
+        final long address = LibraryHolder.libtest.getSymbolAddressWithVersion(name, version);
+        if (address == 0L) {
+            throw new UnsatisfiedLinkError("Could not locate symbol '" + name + "' at version '" + version + "'");
+        }
+        return new Address(address);
+    }
     private static final class NativeInvocationHandler implements InvocationHandler {
         private final ConcurrentMap<Method, MethodInvoker> invokers
             = new ConcurrentHashMap<Method, MethodInvoker>();

src/test/java/com/kenai/jffi/VersionTest.java

@@ -0,0 +1,53 @@
+package com.kenai.jffi;
+
+import com.kenai.jffi.UnitHelper.Address;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class VersionTest {
+    public VersionTest() {
+    }
+
+    @BeforeClass
+    public static void setUpClass() throws Exception {
+    }
+
+    @AfterClass
+    public static void tearDownClass() throws Exception {
+    }
+
+    @Before
+    public void setUp() {
+    }
+
+    @After
+    public void tearDown() {
+    }
+
+    @Test public void old_answer() {
+        Address sym = UnitHelper.findSymbolWithVersion("answer", "VERS_1.0");
+
+        int res = 0;
+        // FIXME: Store answer()'s return value into res
+
+        assertEquals(41, res);
+    }
+
+    @Test public void new_answer() {
+        Address sym = UnitHelper.findSymbolWithVersion("answer", "VERS_1.1");
+
+        int res = 0;
+        // FIXME: Store answer()'s return value into res
+
+        assertEquals(42, res);
+    }
+
+    @Test(expected = UnsatisfiedLinkError.class)
+    public void future_answer() {
+        UnitHelper.findSymbolWithVersion("answer", "VERS_1.2");
+    }
+}