Improved dlsym tests and fixes to linker

Answers the question: what if dependent library
 was preloaded with RTLD_LOCAL flag.

 Also add test for RTLD_NEXT within local_group.

Bug: http://b/17512583
Change-Id: I79e081e68b3a8c0ed8980d4275a06515fea94ec9

linker/linker.cpp

@@ -918,13 +918,17 @@ static bool walk_dependencies_tree(soinfo* root_soinfos[], size_t root_soinfos_s
 }
 
 
-// This is used by dlsym(3).  It performs symbol lookup only within the
-// specified soinfo object and its dependencies in breadth first order.
-const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) {
+static const ElfW(Sym)* dlsym_handle_lookup(soinfo* root, soinfo* skip_until,
+                                            soinfo** found, SymbolName& symbol_name) {
   const ElfW(Sym)* result = nullptr;
-  SymbolName symbol_name(name);
+  bool skip_lookup = skip_until != nullptr;
+
+  walk_dependencies_tree(&root, 1, [&](soinfo* current_soinfo) {
+    if (skip_lookup) {
+      skip_lookup = current_soinfo != skip_until;
+      return true;
+    }
 
-  walk_dependencies_tree(&si, 1, [&](soinfo* current_soinfo) {
     if (!current_soinfo->find_symbol_by_name(symbol_name, nullptr, &result)) {
       result = nullptr;
       return false;
@@ -941,6 +945,13 @@ const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* nam
   return result;
 }
 
+// This is used by dlsym(3).  It performs symbol lookup only within the
+// specified soinfo object and its dependencies in breadth first order.
+const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) {
+  SymbolName symbol_name(name);
+  return dlsym_handle_lookup(si, nullptr, found, symbol_name);
+}
+
 /* This is used by dlsym(3) to performs a global symbol lookup. If the
    start value is null (for RTLD_DEFAULT), the search starts at the
    beginning of the global solist. Otherwise the search starts at the
@@ -978,31 +989,13 @@ const ElfW(Sym)* dlsym_linear_lookup(const char* name,
     }
   }
 
-  // If not found - look into local_group unless
-  // caller is part of the global group in which
+  // If not found - use dlsym_handle_lookup for caller's
+  // local_group unless it is part of the global group in which
   // case we already did it.
   if (s == nullptr && caller != nullptr &&
       (caller->get_rtld_flags() & RTLD_GLOBAL) == 0) {
-    soinfo* local_group_root = caller->get_local_group_root();
-
-    if (handle == RTLD_DEFAULT) {
-      start = local_group_root;
-    }
-
-    for (soinfo* si = start; si != nullptr; si = si->next) {
-      if (si->get_local_group_root() != local_group_root) {
-        break;
-      }
-
-      if (!si->find_symbol_by_name(symbol_name, nullptr, &s)) {
-        return nullptr;
-      }
-
-      if (s != nullptr) {
-        *found = si;
-        break;
-      }
-    }
+    return dlsym_handle_lookup(caller->get_local_group_root(),
+        (handle == RTLD_NEXT) ? caller : nullptr, found, symbol_name);
   }
 
   if (s != nullptr) {

tests/dlfcn_test.cpp

@@ -71,23 +71,80 @@ TEST(dlfcn, dlsym_from_sofile) {
   void* handle = dlopen("libtest_dlsym_from_this.so", RTLD_LAZY | RTLD_LOCAL);
   ASSERT_TRUE(handle != nullptr) << dlerror();
 
-  // check that we cant find '_test_dlsym_symbol' via dlsym(RTLD_DEFAULT)
+  // check that we can't find '_test_dlsym_symbol' via dlsym(RTLD_DEFAULT)
   void* symbol = dlsym(RTLD_DEFAULT, "test_dlsym_symbol");
   ASSERT_TRUE(symbol == nullptr);
   ASSERT_SUBSTR("undefined symbol: test_dlsym_symbol", dlerror());
 
   typedef int* (*fn_t)();
-  fn_t fn = reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol_using_RTLD_DEFAULT"));
+  fn_t lookup_dlsym_symbol_using_RTLD_DEFAULT =
+      reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol_using_RTLD_DEFAULT"));
+  ASSERT_TRUE(lookup_dlsym_symbol_using_RTLD_DEFAULT != nullptr) << dlerror();
 
-  ASSERT_TRUE(fn != nullptr) << dlerror();
-
-  int* ptr = fn();
+  int* ptr = lookup_dlsym_symbol_using_RTLD_DEFAULT();
   ASSERT_TRUE(ptr != nullptr) << dlerror();
   ASSERT_EQ(42, *ptr);
 
+  fn_t lookup_dlsym_symbol2_using_RTLD_DEFAULT =
+      reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol2_using_RTLD_DEFAULT"));
+  ASSERT_TRUE(lookup_dlsym_symbol2_using_RTLD_DEFAULT != nullptr) << dlerror();
+
+  ptr = lookup_dlsym_symbol2_using_RTLD_DEFAULT();
+  ASSERT_TRUE(ptr != nullptr) << dlerror();
+  ASSERT_EQ(44, *ptr);
+
+  fn_t lookup_dlsym_symbol_using_RTLD_NEXT =
+      reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol_using_RTLD_NEXT"));
+  ASSERT_TRUE(lookup_dlsym_symbol_using_RTLD_NEXT != nullptr) << dlerror();
+
+  ptr = lookup_dlsym_symbol_using_RTLD_NEXT();
+  ASSERT_TRUE(ptr != nullptr) << dlerror();
+  ASSERT_EQ(43, *ptr);
+
   dlclose(handle);
 }
 
+TEST(dlfcn, dlsym_from_sofile_with_preload) {
+  void* preload = dlopen("libtest_dlsym_from_this_grandchild.so", RTLD_NOW | RTLD_LOCAL);
+  ASSERT_TRUE(preload != nullptr) << dlerror();
+
+  void* handle = dlopen("libtest_dlsym_from_this.so", RTLD_NOW | RTLD_LOCAL);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+
+  // check that we can't find '_test_dlsym_symbol' via dlsym(RTLD_DEFAULT)
+  void* symbol = dlsym(RTLD_DEFAULT, "test_dlsym_symbol");
+  ASSERT_TRUE(symbol == nullptr);
+  ASSERT_SUBSTR("undefined symbol: test_dlsym_symbol", dlerror());
+
+  typedef int* (*fn_t)();
+  fn_t lookup_dlsym_symbol_using_RTLD_DEFAULT =
+      reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol_using_RTLD_DEFAULT"));
+  ASSERT_TRUE(lookup_dlsym_symbol_using_RTLD_DEFAULT != nullptr) << dlerror();
+
+  int* ptr = lookup_dlsym_symbol_using_RTLD_DEFAULT();
+  ASSERT_TRUE(ptr != nullptr) << dlerror();
+  ASSERT_EQ(42, *ptr);
+
+  fn_t lookup_dlsym_symbol2_using_RTLD_DEFAULT =
+      reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol2_using_RTLD_DEFAULT"));
+  ASSERT_TRUE(lookup_dlsym_symbol2_using_RTLD_DEFAULT != nullptr) << dlerror();
+
+  ptr = lookup_dlsym_symbol2_using_RTLD_DEFAULT();
+  ASSERT_TRUE(ptr != nullptr) << dlerror();
+  ASSERT_EQ(44, *ptr);
+
+  fn_t lookup_dlsym_symbol_using_RTLD_NEXT =
+      reinterpret_cast<fn_t>(dlsym(handle, "lookup_dlsym_symbol_using_RTLD_NEXT"));
+  ASSERT_TRUE(lookup_dlsym_symbol_using_RTLD_NEXT != nullptr) << dlerror();
+
+  ptr = lookup_dlsym_symbol_using_RTLD_NEXT();
+  ASSERT_TRUE(ptr != nullptr) << dlerror();
+  ASSERT_EQ(43, *ptr);
+
+  dlclose(handle);
+  dlclose(preload);
+}
+
 TEST(dlfcn, dlsym_with_dependencies) {
   void* handle = dlopen("libtest_with_dependency.so", RTLD_NOW);
   ASSERT_TRUE(handle != NULL);

tests/libs/Android.mk

@@ -385,11 +385,26 @@ include $(LOCAL_PATH)/Android.build.testlib.mk
 # -----------------------------------------------------------------------------
 # Library to check RTLD_LOCAL with dlsym in 'this'
 # -----------------------------------------------------------------------------
-libtest_dlsym_from_this_src_files := dlsym_from_this.cpp
+libtest_dlsym_from_this_src_files := dlsym_from_this_symbol.cpp
+
+libtest_dlsym_from_this_shared_libraries_target := libdl
+libtest_dlsym_from_this_shared_libraries := libtest_dlsym_from_this_child
 
 module := libtest_dlsym_from_this
-libtest_dlsym_from_this_shared_libraries_target := libdl
+include $(LOCAL_PATH)/Android.build.testlib.mk
 
+# -----------------------------------------------------------------------------
+libtest_dlsym_from_this_child_src_files := dlsym_from_this_functions.cpp
+
+libtest_dlsym_from_this_child_shared_libraries := libtest_dlsym_from_this_grandchild
+
+module := libtest_dlsym_from_this_child
+include $(LOCAL_PATH)/Android.build.testlib.mk
+
+# -----------------------------------------------------------------------------
+libtest_dlsym_from_this_grandchild_src_files := dlsym_from_this_symbol2.cpp
+
+module := libtest_dlsym_from_this_grandchild
 include $(LOCAL_PATH)/Android.build.testlib.mk
 
 # -----------------------------------------------------------------------------

tests/libs/dlsym_from_this_functions.cpp

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 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 <stdio.h>
+
+extern int test_dlsym_symbol;
+
+int test_dlsym_symbol = -1;
+
+extern "C" int* lookup_dlsym_symbol_using_RTLD_DEFAULT() {
+  dlerror();
+  int* result = static_cast<int*>(dlsym(RTLD_DEFAULT, "test_dlsym_symbol"));
+  // TODO: remove this once b/20049306 is fixed
+  if (result == nullptr) {
+    printf("Cannot find the answer\n");
+  }
+  return result;
+}
+
+extern "C" int* lookup_dlsym_symbol2_using_RTLD_DEFAULT() {
+  dlerror();
+  int* result = static_cast<int*>(dlsym(RTLD_DEFAULT, "test_dlsym_symbol2"));
+  // TODO: remove this once b/20049306 is fixed
+  if (result == nullptr) {
+    printf("Cannot find the answer\n");
+  }
+  return result;
+}
+
+extern "C" int* lookup_dlsym_symbol_using_RTLD_NEXT() {
+  dlerror();
+  int* result = static_cast<int*>(dlsym(RTLD_NEXT, "test_dlsym_symbol"));
+  // TODO: remove this once b/20049306 is fixed
+  if (result == nullptr) {
+    printf("Cannot find the answer\n");
+  }
+  return result;
+}
+

tests/libs/dlsym_from_this_symbol.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 The Android Open Source Project
+ * Copyright (C) 2015 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.
@@ -13,18 +13,5 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#include <dlfcn.h>
-#include <stdio.h>
 
 int test_dlsym_symbol = 42;
-
-extern "C" int* lookup_dlsym_symbol_using_RTLD_DEFAULT() {
-  dlerror();
-  int* result = static_cast<int*>(dlsym(RTLD_DEFAULT, "test_dlsym_symbol"));
-  // TODO: remove this once b/20049306 is fixed
-  if (result == nullptr) {
-    printf("Cannot find the answer\n");
-  }
-  return result;
-}
-

tests/libs/dlsym_from_this_symbol2.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+int test_dlsym_symbol = 43;
+int test_dlsym_symbol2 = 44;