Added test for ifunc support in dynamic linker.

ifuncs now work in i386 and x86_64 when called in the same library as
well as in a different library.

Bug:6657325
(cherry picked from commit c5a13efa9bc4264be0a9a9e37c00633af01584ed)

Change-Id: I321d780bc2f9bd1baa749e1acacd2683aefe827b

3 files changed, 84 insertions, 0 deletions

diff --git a/tests/dlfcn_test.cpp b/tests/dlfcn_test.cpp
index 457fcd5..260cbd6 100644
--- a/tests/dlfcn_test.cpp
+++ b/tests/dlfcn_test.cpp
@@ -87,6 +87,39 @@ TEST(dlfcn, dlopen_noload) {
   ASSERT_EQ(0, dlclose(handle2));
 }
 
+// ifuncs are only supported on intel for now
+#if defined(__i386__) || defined(__x86_64__)
+TEST(dlfcn, ifunc) {
+  const char* (*foo_ptr)();
+  const char* (*foo_library_ptr)();
+
+  // ifunc's choice depends on whether IFUNC_CHOICE has a value
+  // first check the set case
+  setenv("IFUNC_CHOICE", "set", 1);
+  void* handle = dlopen("libtest_ifunc.so", RTLD_NOW);
+  ASSERT_TRUE(handle != NULL);
+  *(void **)(&foo_ptr) = dlsym(handle, "foo");
+  *(void **)(&foo_library_ptr) = dlsym(handle, "foo_library");
+  ASSERT_TRUE(foo_ptr != NULL);
+  ASSERT_TRUE(foo_library_ptr != NULL);
+  ASSERT_EQ(strncmp("set", (*foo_ptr)(), 3), 0);
+  ASSERT_EQ(strncmp("set", (*foo_library_ptr)(), 3), 0);
+  dlclose(handle);
+
+  // then check the unset case
+  unsetenv("IFUNC_CHOICE");
+  handle = dlopen("libtest_ifunc.so", RTLD_NOW);
+  ASSERT_TRUE(handle != NULL);
+  *(void **)(&foo_ptr) = dlsym(handle, "foo");
+  *(void **)(&foo_library_ptr) = dlsym(handle, "foo_library");
+  ASSERT_TRUE(foo_ptr != NULL);
+  ASSERT_TRUE(foo_library_ptr != NULL);
+  ASSERT_EQ(strncmp("unset", (*foo_ptr)(), 5), 0);
+  ASSERT_EQ(strncmp("unset", (*foo_library_ptr)(), 3), 0);
+  dlclose(handle);
+}
+#endif
+
 TEST(dlfcn, dlopen_failure) {
   void* self = dlopen("/does/not/exist", RTLD_NOW);
   ASSERT_TRUE(self == NULL);
diff --git a/tests/libs/Android.mk b/tests/libs/Android.mk
index 75df539..8f0ec7a 100644
--- a/tests/libs/Android.mk
+++ b/tests/libs/Android.mk
@@ -115,6 +115,20 @@ build_target := SHARED_LIBRARY
 include $(TEST_PATH)/Android.build.mk
 
 # -----------------------------------------------------------------------------
+# Library used by ifunc tests
+# -----------------------------------------------------------------------------
+ifeq ($(TARGET_ARCH),$(filter $(TARGET_ARCH),x86 x86_64))
+    libtest_ifunc_src_files := \
+        dlopen_testlib_ifunc.c
+
+    LOCAL_SDK_VERSION := current
+    module := libtest_ifunc
+    build_type := target
+    build_target := SHARED_LIBRARY
+    include $(TEST_PATH)/Android.build.mk
+endif
+
+# -----------------------------------------------------------------------------
 # Library used by atexit tests
 # -----------------------------------------------------------------------------
 
diff --git a/tests/libs/dlopen_testlib_ifunc.c b/tests/libs/dlopen_testlib_ifunc.c
new file mode 100644
index 0000000..1c4bafa
--- /dev/null
+++ b/tests/libs/dlopen_testlib_ifunc.c
@@ -0,0 +1,37 @@
+/*
+ * 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+const char* foo() __attribute__ ((ifunc ("foo_ifunc")));
+
+const char* f1() {
+  return "unset";
+}
+
+const char* f2() {
+  return "set";
+}
+
+void* foo_ifunc() {
+   char* choice = getenv("IFUNC_CHOICE");
+   return choice == NULL ? f1 : f2;
+}
+
+const char* foo_library() {
+   return foo();
+}
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