Add functions to provide target sdk version

Bug: http://b/21364029
Change-Id: I8648d1bff6c8fd6e7cd12da7f128e048b9f2829a
(cherry picked from commit 79fd668bb4ddb22432eeda2ebd8d10359013d9a8)

9 files changed, 138 insertions, 15 deletions

diff --git a/libdl/Android.mk b/libdl/Android.mk
index 2a0724a0b..7b97dc4ad 100644
--- a/libdl/Android.mk
+++ b/libdl/Android.mk
@@ -15,7 +15,7 @@ include $(CLEAR_VARS)
 #
 # DO NOT REMOVE --exclude-libs!
 
-LOCAL_LDFLAGS := -Wl,--exclude-libs=libgcc.a
+LOCAL_LDFLAGS := -Wl,--exclude-libs=libgcc.a -Wl,--version-script=$(LOCAL_PATH)/libdl.map
 
 # for x86, exclude libgcc_eh.a for the same reasons as above
 LOCAL_LDFLAGS_x86 := -Wl,--exclude-libs=libgcc_eh.a
diff --git a/libdl/libdl.c b/libdl/libdl.c
index dca51b0b0..9a858a36e 100644
--- a/libdl/libdl.c
+++ b/libdl/libdl.c
@@ -17,6 +17,7 @@
 #include <dlfcn.h>
 #include <link.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <android/dlext.h>
 
 // These are stubs for functions that are actually defined
@@ -38,3 +39,6 @@ void android_get_LD_LIBRARY_PATH(char* buffer __unused, size_t buffer_size __unu
 void android_update_LD_LIBRARY_PATH(const char* ld_library_path __unused) { }
 
 void* android_dlopen_ext(const char* filename __unused, int flag __unused, const android_dlextinfo* extinfo __unused) { return 0; }
+
+void android_set_application_target_sdk_version(uint32_t target __unused) { }
+uint32_t android_get_application_target_sdk_version() { return 0; }
diff --git a/libdl/libdl.map b/libdl/libdl.map
new file mode 100644
index 000000000..a911cb67a
--- /dev/null
+++ b/libdl/libdl.map
@@ -0,0 +1,39 @@
+#
+# 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.
+#
+
+LIBC {
+  global:
+    android_dlopen_ext;
+    dl_iterate_phdr;
+# begin arm-only
+    dl_unwind_find_exidx;
+# end arm-only
+    dladdr;
+    dlclose;
+    dlerror;
+    dlopen;
+    dlsym;
+  local:
+    *;
+};
+
+LIBC_PRIVATE {
+  global:
+    android_get_application_target_sdk_version;
+    android_set_application_target_sdk_version;
+    android_get_LD_LIBRARY_PATH;
+    android_update_LD_LIBRARY_PATH;
+} LIBC;
diff --git a/linker/Android.mk b/linker/Android.mk
index 4a7da7608..00add7da9 100644
--- a/linker/Android.mk
+++ b/linker/Android.mk
@@ -7,6 +7,7 @@ LOCAL_SRC_FILES:= \
     dlfcn.cpp \
     linker.cpp \
     linker_allocator.cpp \
+    linker_sdk_versions.cpp \
     linker_block_allocator.cpp \
     linker_environ.cpp \
     linker_libc_support.c \
diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 057c2173c..8fafded6a 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -157,6 +157,14 @@ int dlclose(void* handle) {
   return 0;
 }
 
+void android_set_application_target_sdk_version(uint32_t target) {
+  set_application_target_sdk_version(target);
+}
+
+uint32_t android_get_application_target_sdk_version() {
+  return get_application_target_sdk_version();
+}
+
 // name_offset: starting index of the name in libdl_info.strtab
 #define ELF32_SYM_INITIALIZER(name_offset, value, shndx) \
     { name_offset, \
@@ -176,19 +184,21 @@ int dlclose(void* handle) {
       /* st_size */ 0, \
     }
 
+static const char ANDROID_LIBDL_STRTAB[] =
+  // 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 99999
+  // 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 56789
+    "dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_it"
+  // 00000000001 1111111112222222222 3333333333444444444455555555556666666666777 777777788888888889999999999
+  // 01234567890 1234567890123456789 0123456789012345678901234567890123456789012 345678901234567890123456789
+    "erate_phdr\0android_dlopen_ext\0android_set_application_target_sdk_version\0android_get_application_tar"
+  // 0000000000111111
+  // 0123456789012345
+    "get_sdk_version\0"
 #if defined(__arm__)
-  // 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 9999900000000001 1111111112222222222 333333333344444444445
-  // 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 5678901234567890 1234567890123456789 012345678901234567890
-#  define ANDROID_LIBDL_STRTAB \
-    "dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_iterate_phdr\0android_dlopen_ext\0dl_unwind_find_exidx\0"
-#elif defined(__aarch64__) || defined(__i386__) || defined(__mips__) || defined(__x86_64__)
-  // 0000000 00011111 111112 22222222 2333333 3333444444444455555555556666666 6667777777777888888888899999 9999900000000001 1111111112222222222
-  // 0123456 78901234 567890 12345678 9012345 6789012345678901234567890123456 7890123456789012345678901234 5678901234567890 1234567890123456789
-#  define ANDROID_LIBDL_STRTAB \
-    "dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0android_update_LD_LIBRARY_PATH\0android_get_LD_LIBRARY_PATH\0dl_iterate_phdr\0android_dlopen_ext\0"
-#else
-#  error Unsupported architecture. Only arm, arm64, mips, mips64, x86 and x86_64 are presently supported.
+  // 216
+    "dl_unwind_find_exidx\0"
 #endif
+    ;
 
 static ElfW(Sym) g_libdl_symtab[] = {
   // Total length of libdl_info.strtab, including trailing 0.
@@ -205,8 +215,10 @@ static ElfW(Sym) g_libdl_symtab[] = {
   ELFW(SYM_INITIALIZER)( 67, &android_get_LD_LIBRARY_PATH, 1),
   ELFW(SYM_INITIALIZER)( 95, &dl_iterate_phdr, 1),
   ELFW(SYM_INITIALIZER)(111, &android_dlopen_ext, 1),
+  ELFW(SYM_INITIALIZER)(130, &android_set_application_target_sdk_version, 1),
+  ELFW(SYM_INITIALIZER)(173, &android_get_application_target_sdk_version, 1),
 #if defined(__arm__)
-  ELFW(SYM_INITIALIZER)(130, &dl_unwind_find_exidx, 1),
+  ELFW(SYM_INITIALIZER)(216, &dl_unwind_find_exidx, 1),
 #endif
 };
 
@@ -223,9 +235,9 @@ static ElfW(Sym) g_libdl_symtab[] = {
 // Note that adding any new symbols here requires stubbing them out in libdl.
 static unsigned g_libdl_buckets[1] = { 1 };
 #if defined(__arm__)
-static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0 };
+static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 0 };
 #else
-static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
+static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 0 };
 #endif
 
 static uint8_t __libdl_info_buf[sizeof(soinfo)] __attribute__((aligned(8)));
diff --git a/linker/linker.h b/linker/linker.h
index c7118ea6a..04b584ed5 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -429,4 +429,7 @@ extern "C" void notify_gdb_of_libraries();
 char* linker_get_error_buffer();
 size_t linker_get_error_buffer_size();
 
+void set_application_target_sdk_version(uint32_t target);
+uint32_t get_application_target_sdk_version();
+
 #endif
diff --git a/linker/linker_sdk_versions.cpp b/linker/linker_sdk_versions.cpp
new file mode 100644
index 000000000..c73eb38d9
--- /dev/null
+++ b/linker/linker_sdk_versions.cpp
@@ -0,0 +1,29 @@
+/*
+ * 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 "linker.h"
+#include <atomic>
+
+static std::atomic<uint32_t> g_target_sdk_version;
+
+void set_application_target_sdk_version(uint32_t target) {
+  g_target_sdk_version = target;
+}
+
+uint32_t get_application_target_sdk_version() {
+  return g_target_sdk_version;
+}
+
diff --git a/tests/Android.mk b/tests/Android.mk
index 14f0d324c..0f3454cbf 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -49,6 +49,9 @@ endif
 test_cppflags = \
     -std=gnu++11 \
 
+libBionicStandardTests_src_files_target := \
+    libdl_test.cpp \
+
 libBionicStandardTests_src_files := \
     arpa_inet_test.cpp \
     buffer_tests.cpp \
diff --git a/tests/libdl_test.cpp b/tests/libdl_test.cpp
new file mode 100644
index 000000000..9aab87b88
--- /dev/null
+++ b/tests/libdl_test.cpp
@@ -0,0 +1,32 @@
+/*
+ * 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 <gtest/gtest.h>
+
+extern "C" uint32_t android_get_application_target_sdk_version();
+extern "C" void android_set_application_target_sdk_version(uint32_t target);
+
+TEST(libdl, application_sdk_versions_smoke) {
+  // Check initial values
+  ASSERT_EQ(0U, android_get_application_target_sdk_version());
+
+  android_set_application_target_sdk_version(20U);
+  ASSERT_EQ(20U, android_get_application_target_sdk_version());
+
+  android_set_application_target_sdk_version(22U);
+  ASSERT_EQ(22U, android_get_application_target_sdk_version());
+}
+