Merge "Fix weak function lookups"

linker/dlfcn.cpp

@@ -118,7 +118,7 @@ void* dlsym(void* handle, const char* symbol) {
   if (sym != NULL) {
     unsigned bind = ELF_ST_BIND(sym->st_info);
 
-    if (bind == STB_GLOBAL && sym->st_shndx != 0) {
+    if ((bind == STB_GLOBAL || bind == STB_WEAK) && sym->st_shndx != 0) {
       return reinterpret_cast<void*>(sym->st_value + found->load_bias);
     }
 

tests/dlfcn_test.cpp

@@ -254,6 +254,18 @@ TEST(dlfcn, rtld_next_known_symbol) {
   ASSERT_TRUE(addr != NULL);
 }
 
+TEST(dlfcn, dlsym_weak_func) {
+  dlerror();
+  void* handle = dlopen("libtest_dlsym_weak_func.so",RTLD_NOW);
+  ASSERT_TRUE(handle != NULL);
+
+  int (*weak_func)();
+  weak_func = reinterpret_cast<int (*)()>(dlsym(handle, "weak_func"));
+  ASSERT_TRUE(weak_func != NULL) << "dlerror: " << dlerror();
+  EXPECT_EQ(42, weak_func());
+  dlclose(handle);
+}
+
 TEST(dlfcn, dlopen_symlink) {
   void* handle1 = dlopen("libdlext_test.so", RTLD_NOW);
   void* handle2 = dlopen("libdlext_test_v2.so", RTLD_NOW);

tests/libs/Android.mk

@@ -103,3 +103,15 @@ include $(TEST_PATH)/Android.build.mk
 build_type := host
 include $(TEST_PATH)/Android.build.mk
 
+# -----------------------------------------------------------------------------
+# Library with weak function
+# -----------------------------------------------------------------------------
+libtest_dlsym_weak_func_src_files := \
+    dlsym_weak_function.cpp
+
+module := libtest_dlsym_weak_func
+build_target := SHARED_LIBRARY
+build_type := target
+include $(TEST_PATH)/Android.build.mk
+build_type := host
+include $(TEST_PATH)/Android.build.mk

tests/libs/dlsym_weak_function.cpp

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+extern "C" int __attribute__((weak)) weak_func() {
+  return 42;
+}
+