Move platform-private symbols out of libdl.so

Symbols not intended to be accessible from apps are moved to libdl_android.so

Test: bionic-unit-tests
Bug: http://b/129387775
Change-Id: Ib8ba6147a20cf56550c9a008f66570a2d419565a
(cherry picked from commit 2d6be9a751685b4c307632bf27e8c100310ad500)
diff --git a/libdl/libdl_android.cpp b/libdl/libdl_android.cpp
new file mode 100644
index 0000000..9ad8250
--- /dev/null
+++ b/libdl/libdl_android.cpp
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2007 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 <dlfcn.h>
+#include <link.h>
+#include <stdlib.h>
+#include <android/dlext.h>
+
+// These functions are exported by the loader
+// TODO(dimitry): replace these with reference to libc.so
+
+extern "C" {
+
+__attribute__((__weak__, visibility("default")))
+void __loader_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size);
+
+__attribute__((__weak__, visibility("default")))
+    void __loader_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
+
+__attribute__((__weak__, visibility("default")))
+void __loader_android_set_application_target_sdk_version(int target);
+
+__attribute__((__weak__, visibility("default")))
+bool __loader_android_init_anonymous_namespace(const char* shared_libs_sonames,
+                                               const char* library_search_path);
+
+__attribute__((__weak__, visibility("default")))
+struct android_namespace_t* __loader_android_create_namespace(
+                                const char* name,
+                                const char* ld_library_path,
+                                const char* default_library_path,
+                                uint64_t type,
+                                const char* permitted_when_isolated_path,
+                                struct android_namespace_t* parent,
+                                const void* caller_addr);
+
+__attribute__((__weak__, visibility("default")))
+bool __loader_android_link_namespaces(
+                                struct android_namespace_t* namespace_from,
+                                struct android_namespace_t* namespace_to,
+                                const char* shared_libs_sonames);
+
+__attribute__((__weak__, visibility("default")))
+void __loader_android_dlwarning(void* obj, void (*f)(void*, const char*));
+
+__attribute__((__weak__, visibility("default")))
+struct android_namespace_t* __loader_android_get_exported_namespace(const char* name);
+
+// Proxy calls to bionic loader
+__attribute__((__weak__))
+void android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
+  __loader_android_get_LD_LIBRARY_PATH(buffer, buffer_size);
+}
+
+__attribute__((__weak__))
+void android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
+  __loader_android_update_LD_LIBRARY_PATH(ld_library_path);
+}
+
+__attribute__((__weak__))
+void android_set_application_target_sdk_version(int target) {
+  __loader_android_set_application_target_sdk_version(target);
+}
+
+__attribute__((__weak__))
+bool android_init_anonymous_namespace(const char* shared_libs_sonames,
+                                      const char* library_search_path) {
+  return __loader_android_init_anonymous_namespace(shared_libs_sonames, library_search_path);
+}
+
+__attribute__((__weak__))
+struct android_namespace_t* android_create_namespace(const char* name,
+                                                     const char* ld_library_path,
+                                                     const char* default_library_path,
+                                                     uint64_t type,
+                                                     const char* permitted_when_isolated_path,
+                                                     struct android_namespace_t* parent) {
+  const void* caller_addr = __builtin_return_address(0);
+  return __loader_android_create_namespace(name,
+                                           ld_library_path,
+                                           default_library_path,
+                                           type,
+                                           permitted_when_isolated_path,
+                                           parent,
+                                           caller_addr);
+}
+
+__attribute__((__weak__))
+bool android_link_namespaces(struct android_namespace_t* namespace_from,
+                             struct android_namespace_t* namespace_to,
+                             const char* shared_libs_sonames) {
+  return __loader_android_link_namespaces(namespace_from, namespace_to, shared_libs_sonames);
+}
+
+__attribute__((__weak__))
+void android_dlwarning(void* obj, void (*f)(void*, const char*)) {
+  __loader_android_dlwarning(obj, f);
+}
+
+__attribute__((__weak__))
+struct android_namespace_t* android_get_exported_namespace(const char* name) {
+  return __loader_android_get_exported_namespace(name);
+}
+
+#if defined(__arm__)
+// An arm32 unwinding table has an R_ARM_NONE relocation to
+// __aeabi_unwind_cpp_pr0. This shared library will never invoke the unwinder,
+// so it doesn't actually need the routine. Define a dummy version here,
+// because the real version calls libc functions (e.g. memcpy, abort), which
+// would create a dependency cycle with libc.so.
+__attribute__((visibility("hidden")))
+void __aeabi_unwind_cpp_pr0() {
+  __builtin_trap();
+}
+#endif
+
+} // extern "C"