Revert "Revert "Add RTLD_NODELETE flag support""

This reverts commit 69c5d108a5.

libc/include/dlfcn.h

@@ -64,6 +64,7 @@ enum {
   RTLD_GLOBAL = 2,
 #endif
   RTLD_NOLOAD = 4,
+  RTLD_NODELETE = 0x01000,
 };
 
 #if defined (__LP64__)

linker/linker.cpp

@@ -987,6 +987,11 @@ static soinfo* find_library(const char* name, int rtld_flags, const android_dlex
 }
 
 static void soinfo_unload(soinfo* si) {
+  if (!si->can_unload()) {
+    TRACE("not unloading '%s' - the binary is flagged with NODELETE", si->name);
+    return;
+  }
+
   if (si->ref_count == 1) {
     TRACE("unloading '%s'", si->name);
     si->CallDestructors();
@@ -1045,7 +1050,7 @@ void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
 }
 
 soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo) {
-  if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NOLOAD)) != 0) {
+  if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NODELETE|RTLD_NOLOAD)) != 0) {
     DL_ERR("invalid flags to dlopen: %x", flags);
     return nullptr;
   }
@@ -1808,6 +1813,9 @@ const char* soinfo::get_string(ElfW(Word) index) const {
   return strtab + index;
 }
 
+bool soinfo::can_unload() const {
+  return (rtld_flags & (RTLD_NODELETE | RTLD_GLOBAL)) == 0;
+}
 /* Force any of the closed stdin, stdout and stderr to be associated with
    /dev/null. */
 static int nullify_closed_stdio() {
@@ -2111,9 +2119,13 @@ bool soinfo::PrelinkImage() {
         if ((d->d_un.d_val & DF_1_GLOBAL) != 0) {
           rtld_flags |= RTLD_GLOBAL;
         }
+
+        if ((d->d_un.d_val & DF_1_NODELETE) != 0) {
+          rtld_flags |= RTLD_NODELETE;
+        }
         // TODO: Implement other flags
 
-        if ((d->d_un.d_val & ~(DF_1_NOW | DF_1_GLOBAL)) != 0) {
+        if ((d->d_un.d_val & ~(DF_1_NOW | DF_1_GLOBAL | DF_1_NODELETE)) != 0) {
           DL_WARN("Unsupported flags DT_FLAGS_1=%p", reinterpret_cast<void*>(d->d_un.d_val));
         }
         break;

linker/linker.h

@@ -134,7 +134,7 @@ struct soinfo {
 #endif
 
   soinfo* next;
-  unsigned flags;
+  uint32_t flags;
 
  private:
   const char* strtab;
@@ -143,8 +143,8 @@ struct soinfo {
 
   size_t nbucket;
   size_t nchain;
-  unsigned* bucket;
+  uint32_t* bucket;
-  unsigned* chain;
+  uint32_t* chain;
 
 #if defined(__mips__) || !defined(__LP64__)
   // This is only used by mips and mips64, but needs to be here for
@@ -179,12 +179,12 @@ struct soinfo {
 
 #if defined(__arm__)
   // ARM EABI section used for stack unwinding.
-  unsigned* ARM_exidx;
+  uint32_t* ARM_exidx;
   size_t ARM_exidx_count;
 #elif defined(__mips__)
-  unsigned mips_symtabno;
+  uint32_t mips_symtabno;
-  unsigned mips_local_gotno;
+  uint32_t mips_local_gotno;
-  unsigned mips_gotsym;
+  uint32_t mips_gotsym;
 #endif
 
   size_t ref_count;
@@ -224,10 +224,12 @@ struct soinfo {
   ElfW(Addr) resolve_symbol_address(ElfW(Sym)* s);
 
   const char* get_string(ElfW(Word) index) const;
+  bool can_unload() const;
 
   bool inline has_min_version(uint32_t min_version) const {
     return (flags & FLAG_NEW_SOINFO) != 0 && version >= min_version;
   }
+
  private:
   void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse);
   void CallFunction(const char* function_name, linker_function_t function);
@@ -258,7 +260,7 @@ struct soinfo {
   friend soinfo* get_libdl_info();
 };
 
-extern soinfo* get_libdl_info();
+soinfo* get_libdl_info();
 
 void do_android_get_LD_LIBRARY_PATH(char*, size_t);
 void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);

tests/dlfcn_test.cpp

@@ -232,10 +232,15 @@ TEST(dlfcn, dlopen_check_rtld_global) {
   ASSERT_TRUE(sym == nullptr);
 
   void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_GLOBAL);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
   sym = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
   ASSERT_TRUE(sym != nullptr) << dlerror();
   ASSERT_TRUE(reinterpret_cast<bool (*)(void)>(sym)());
   dlclose(handle);
+
+  // RTLD_GLOBAL implies RTLD_NODELETE, let's check that
+  void* sym_after_dlclose = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
+  ASSERT_EQ(sym, sym_after_dlclose);
 }
 
 // libtest_with_dependency_loop.so -> libtest_with_dependency_loop_a.so ->
@@ -263,6 +268,81 @@ TEST(dlfcn, dlopen_check_loop) {
 #endif
 }
 
+TEST(dlfcn, dlopen_nodelete) {
+  static bool is_unloaded = false;
+
+  void* handle = dlopen("libtest_nodelete_1.so", RTLD_NOW | RTLD_NODELETE);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  void (*set_unload_flag_ptr)(bool*);
+  set_unload_flag_ptr = reinterpret_cast<void (*)(bool*)>(dlsym(handle, "dlopen_nodelete_1_set_unload_flag_ptr"));
+  ASSERT_TRUE(set_unload_flag_ptr != nullptr) << dlerror();
+  set_unload_flag_ptr(&is_unloaded);
+
+  uint32_t* taxicab_number = reinterpret_cast<uint32_t*>(dlsym(handle, "dlopen_nodelete_1_taxicab_number"));
+  ASSERT_TRUE(taxicab_number != nullptr) << dlerror();
+  ASSERT_EQ(1729U, *taxicab_number);
+  *taxicab_number = 2;
+
+  dlclose(handle);
+  ASSERT_TRUE(!is_unloaded);
+
+  uint32_t* taxicab_number_after_dlclose = reinterpret_cast<uint32_t*>(dlsym(handle, "dlopen_nodelete_1_taxicab_number"));
+  ASSERT_EQ(taxicab_number_after_dlclose, taxicab_number);
+  ASSERT_EQ(2U, *taxicab_number_after_dlclose);
+
+
+  handle = dlopen("libtest_nodelete_1.so", RTLD_NOW);
+  uint32_t* taxicab_number2 = reinterpret_cast<uint32_t*>(dlsym(handle, "dlopen_nodelete_1_taxicab_number"));
+  ASSERT_EQ(taxicab_number2, taxicab_number);
+
+  ASSERT_EQ(2U, *taxicab_number2);
+
+  dlclose(handle);
+  ASSERT_TRUE(!is_unloaded);
+}
+
+TEST(dlfcn, dlopen_nodelete_on_second_dlopen) {
+  static bool is_unloaded = false;
+
+  void* handle = dlopen("libtest_nodelete_2.so", RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  void (*set_unload_flag_ptr)(bool*);
+  set_unload_flag_ptr = reinterpret_cast<void (*)(bool*)>(dlsym(handle, "dlopen_nodelete_2_set_unload_flag_ptr"));
+  ASSERT_TRUE(set_unload_flag_ptr != nullptr) << dlerror();
+  set_unload_flag_ptr(&is_unloaded);
+
+  uint32_t* taxicab_number = reinterpret_cast<uint32_t*>(dlsym(handle, "dlopen_nodelete_2_taxicab_number"));
+  ASSERT_TRUE(taxicab_number != nullptr) << dlerror();
+
+  ASSERT_EQ(1729U, *taxicab_number);
+  *taxicab_number = 2;
+
+  // This RTLD_NODELETE should be ignored
+  void* handle1 = dlopen("libtest_nodelete_2.so", RTLD_NOW | RTLD_NODELETE);
+  ASSERT_TRUE(handle1 != nullptr) << dlerror();
+  ASSERT_EQ(handle, handle1);
+
+  dlclose(handle1);
+  dlclose(handle);
+
+  ASSERT_TRUE(is_unloaded);
+}
+
+TEST(dlfcn, dlopen_nodelete_dt_flags_1) {
+  static bool is_unloaded = false;
+
+  void* handle = dlopen("libtest_nodelete_dt_flags_1.so", RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  void (*set_unload_flag_ptr)(bool*);
+  set_unload_flag_ptr = reinterpret_cast<void (*)(bool*)>(dlsym(handle, "dlopen_nodelete_dt_flags_1_set_unload_flag_ptr"));
+  ASSERT_TRUE(set_unload_flag_ptr != nullptr) << dlerror();
+  set_unload_flag_ptr(&is_unloaded);
+
+  dlclose(handle);
+  ASSERT_TRUE(!is_unloaded);
+}
+
+
 TEST(dlfcn, dlopen_failure) {
   void* self = dlopen("/does/not/exist", RTLD_NOW);
   ASSERT_TRUE(self == NULL);

tests/libs/Android.mk

@@ -120,6 +120,35 @@ libtest_simple_src_files := \
 module := libtest_simple
 include $(LOCAL_PATH)/Android.build.testlib.mk
 
+# -----------------------------------------------------------------------------
+# Library used by dlfcn nodelete tests
+# -----------------------------------------------------------------------------
+libtest_nodelete_1_src_files := \
+    dlopen_nodelete_1.cpp
+
+module := libtest_nodelete_1
+include $(LOCAL_PATH)/Android.build.testlib.mk
+
+# -----------------------------------------------------------------------------
+# Library used by dlfcn nodelete tests
+# -----------------------------------------------------------------------------
+libtest_nodelete_2_src_files := \
+    dlopen_nodelete_2.cpp
+
+module := libtest_nodelete_2
+include $(LOCAL_PATH)/Android.build.testlib.mk
+
+# -----------------------------------------------------------------------------
+# Library used by dlfcn nodelete tests
+# -----------------------------------------------------------------------------
+libtest_nodelete_dt_flags_1_src_files := \
+    dlopen_nodelete_dt_flags_1.cpp
+
+libtest_nodelete_dt_flags_1_ldflags := -Wl,-z,nodelete
+
+module := libtest_nodelete_dt_flags_1
+include $(LOCAL_PATH)/Android.build.testlib.mk
+
 # -----------------------------------------------------------------------------
 # Libraries used by dlfcn tests to verify correct load order:
 # libtest_check_order_2_right.so

tests/libs/dlopen_nodelete_1.cpp

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014 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 <stdint.h>
+#include <stdlib.h>
+
+uint32_t dlopen_nodelete_1_taxicab_number = 1729;
+static bool* unload_flag_ptr = nullptr;
+
+extern "C" void dlopen_nodelete_1_set_unload_flag_ptr(bool* ptr) {
+  unload_flag_ptr = ptr;
+}
+
+static void __attribute__((destructor)) unload_guard() {
+  if (unload_flag_ptr != nullptr) {
+    *unload_flag_ptr = true;
+  }
+}

tests/libs/dlopen_nodelete_2.cpp

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2014 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 <stdint.h>
+#include <stdlib.h>
+
+uint32_t dlopen_nodelete_2_taxicab_number = 1729;
+static bool* unload_flag_ptr = nullptr;
+
+extern "C" void dlopen_nodelete_2_set_unload_flag_ptr(bool* ptr) {
+  unload_flag_ptr = ptr;
+}
+
+static void __attribute__((destructor)) unload_guard() {
+  if (unload_flag_ptr != nullptr) {
+    *unload_flag_ptr = true;
+  }
+}

tests/libs/dlopen_nodelete_dt_flags_1.cpp

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2014 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 <stdint.h>
+#include <stdlib.h>
+
+static bool* unload_flag_ptr = nullptr;
+
+extern "C" void dlopen_nodelete_dt_flags_1_set_unload_flag_ptr(bool* ptr) {
+  unload_flag_ptr = ptr;
+}
+
+static void __attribute__((destructor)) unload_guard() {
+  if (unload_flag_ptr != nullptr) {
+    *unload_flag_ptr = true;
+  }
+}