commit 1ffec1cc4d0e283bb1ff6f49843769a3493b8d73
author Dmitriy Ivanov <dimitry@google.com> Mon Nov 23 11:26:35 2015 -0800
committer Dmitriy Ivanov <dimitry@google.com> Mon Nov 23 16:13:10 2015 -0800
tree 083c8af007b9a2e2ed01fbde2eea50ded648e114
parent a7fc7f9909c221a0f64c5c5ecc5fadd5fba467c5

Introduce anonymous namespace

The anonymous namespace is introduced to
handle cases when linker can not find the
caller. This usually happens when caller
code was not loaded by dynamic linker;
for example mono-generated code.

Bug: http://b/25844435
Bug: http://b/22548808
Change-Id: I9e5b1d23c1c75bc78548d68e79216a6a943a33cf

linker/linker.cpp

diff --git a/linker/linker.cpp b/linker/linker.cpp
index 1ecf65b..9780231 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -111,6 +111,7 @@
 };
 
 android_namespace_t g_default_namespace;
+android_namespace_t* g_anonymous_namespace = &g_default_namespace;
 
 static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf);
 
@@ -2201,7 +2202,7 @@
     return nullptr;
   }
 
-  android_namespace_t* ns = caller->get_namespace();
+  android_namespace_t* ns = caller != nullptr ? caller->get_namespace() : g_anonymous_namespace;
 
   if (extinfo != nullptr) {
     if ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0) {
@@ -2246,14 +2247,14 @@
   soinfo_unload(si);
 }
 
-bool init_public_namespace(const char* libs) {
-  CHECK(libs != nullptr);
+bool init_namespaces(const char* public_ns_sonames, const char* anon_ns_library_path) {
+  CHECK(public_ns_sonames != nullptr);
   if (g_public_namespace_initialized) {
-    DL_ERR("Public namespace has already been initialized.");
+    DL_ERR("public namespace has already been initialized.");
     return false;
   }
 
-  std::vector<std::string> sonames = android::base::Split(libs, ":");
+  std::vector<std::string> sonames = android::base::Split(public_ns_sonames, ":");
 
   ProtectedDataGuard guard;
 
@@ -2267,7 +2268,7 @@
     find_loaded_library_by_soname(&g_default_namespace, soname.c_str(), &candidate);
 
     if (candidate == nullptr) {
-      DL_ERR("Error initializing public namespace: \"%s\" was not found"
+      DL_ERR("error initializing public namespace: \"%s\" was not found"
              " in the default namespace", soname.c_str());
       return false;
     }
@@ -2276,8 +2277,18 @@
     g_public_namespace.push_back(candidate);
   }
 
-  failure_guard.disable();
   g_public_namespace_initialized = true;
+
+  // create anonymous namespace
+  android_namespace_t* anon_ns =
+      create_namespace("(anonymous)", nullptr, anon_ns_library_path, false);
+
+  if (anon_ns == nullptr) {
+    g_public_namespace_initialized = false;
+    return false;
+  }
+  g_anonymous_namespace = anon_ns;
+  failure_guard.disable();
   return true;
 }
 
@@ -2286,7 +2297,7 @@
                                       const char* default_library_path,
                                       bool is_isolated) {
   if (!g_public_namespace_initialized) {
-    DL_ERR("Cannot create namespace: public namespace is not initialized.");
+    DL_ERR("cannot create namespace: public namespace is not initialized.");
     return nullptr;
   }