commit d7c4832e6a640be972017e85ab21e72950dfeddd
author Jiyong Park <jiyong@google.com> Mon Apr 03 23:10:37 2017 +0900
committer Iliyan Malchev <malchev@google.com> Thu Apr 06 15:20:04 2017 -0700
tree f7000710a10e5c7602802c8f1ea7622a933da718
parent f971076ac9586e844bb8f342f5f3a12b91d934fb

linker: add android_get_exported_namespace

Depending on how ld.config.txt is configured, there can be multiple
built-in namespaces created by the linker from the beginning of a
process. android_get_exported_namespace is a platform only API for
getting a handle (android_namespace_t*) to one of the built-in namespaces
with given name. The returned namespace can then be given to
android_dlopen_ext in order to explicitly specify the target namespace
where the library is searched and loaded from.

Note that this function only returns 'exported' namespaces created via
ld.config.txt file. In order to export a namespace, the visible property
should be set to true:

namespace.<name>.visible = true

Namespaces are hidden by default. Hidden namespaces and namespaces
that are created programmatically, notably 'classloader-namespace',
aren't returned by this function.

Bug: 36851137
Test: confirmed that namespaces created with ld.config.txt is retrieved.
Test: linker-unit-tests passes
Change-Id: I0d05fa7e0e116009edf8ea362ab46774bc617cbf

linker/tests/linker_config_test.cpp

diff --git a/linker/tests/linker_config_test.cpp b/linker/tests/linker_config_test.cpp
index 64ab00f..4889b14 100644
--- a/linker/tests/linker_config_test.cpp
+++ b/linker/tests/linker_config_test.cpp
@@ -59,6 +59,7 @@
   "namespace.default.links = system\n"
   "namespace.default.link.system.shared_libs = libc.so:libm.so:libdl.so:libstdc++.so\n"
   "namespace.system.isolated = true\n"
+  "namespace.system.visible = true\n"
   "namespace.system.search.paths = /system/${LIB}\n"
   "namespace.system.permitted.paths = /system/${LIB}\n"
   "namespace.system.asan.search.paths = /data:/system/${LIB}\n"
@@ -139,6 +140,7 @@
   ASSERT_TRUE(default_ns_config != nullptr);
 
   ASSERT_TRUE(default_ns_config->isolated());
+  ASSERT_FALSE(default_ns_config->visible());
   ASSERT_EQ(kExpectedDefaultSearchPath, default_ns_config->search_paths());
   ASSERT_EQ(kExpectedDefaultPermittedPath, default_ns_config->permitted_paths());
 
@@ -165,6 +167,7 @@
   ASSERT_TRUE(ns_system != nullptr) << "system namespace was not found";
 
   ASSERT_TRUE(ns_system->isolated());
+  ASSERT_TRUE(ns_system->visible());
   ASSERT_EQ(kExpectedSystemSearchPath, ns_system->search_paths());
   ASSERT_EQ(kExpectedSystemPermittedPath, ns_system->permitted_paths());
 }