tests/dlext_test.cpp - platform/bionic - Git at Google

 /*
  * 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 <gtest/gtest.h>

 #include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <android/dlext.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <sys/wait.h>

 #include <pagemap/pagemap.h>


 #define ASSERT_DL_NOTNULL(ptr) \
     ASSERT_TRUE(ptr != NULL) << "dlerror: " << dlerror()

 #define ASSERT_DL_ZERO(i) \
     ASSERT_EQ(0, i) << "dlerror: " << dlerror()

 #define ASSERT_NOERROR(i) \
     ASSERT_NE(-1, i) << "errno: " << strerror(errno)


 typedef int (*fn)(void);
 #define LIBNAME "libdlext_test.so"
 #define LIBNAME_NORELRO "libdlext_test_norelro.so"
 #define LIBSIZE 1024*1024 // how much address space to reserve for it

 #if defined(__LP64__)
 #define LIBPATH "%s/nativetest64/libdlext_test_fd/libdlext_test_fd.so"
 #else
 #define LIBPATH "%s/nativetest/libdlext_test_fd/libdlext_test_fd.so"
 #endif

 class DlExtTest : public ::testing::Test {
 protected:
   virtual void SetUp() {
     handle_ = NULL;
     // verify that we don't have the library loaded already
     ASSERT_EQ(NULL, dlsym(RTLD_DEFAULT, "getRandomNumber"));
     // call dlerror() to swallow the error, and check it was the one we wanted
     ASSERT_STREQ("undefined symbol: getRandomNumber", dlerror());
   }

   virtual void TearDown() {
     if (handle_ != NULL) {
       ASSERT_DL_ZERO(dlclose(handle_));
     }
   }

   void* handle_;
 };

 TEST_F(DlExtTest, ExtInfoNull) {
   handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, NULL);
   ASSERT_DL_NOTNULL(handle_);
   fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
   ASSERT_DL_NOTNULL(f);
   EXPECT_EQ(4, f());
 }

 TEST_F(DlExtTest, ExtInfoNoFlags) {
   android_dlextinfo extinfo;
   extinfo.flags = 0;
   handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
   ASSERT_DL_NOTNULL(handle_);
   fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
   ASSERT_DL_NOTNULL(f);
   EXPECT_EQ(4, f());
 }

 TEST_F(DlExtTest, ExtInfoUseFd) {
   const char* android_data = getenv("ANDROID_DATA");
   ASSERT_TRUE(android_data != NULL);
   char lib_path[PATH_MAX];
   snprintf(lib_path, sizeof(lib_path), LIBPATH, android_data);

   android_dlextinfo extinfo;
   extinfo.flags = ANDROID_DLEXT_USE_LIBRARY_FD;
   extinfo.library_fd = TEMP_FAILURE_RETRY(open(lib_path, O_RDONLY | O_CLOEXEC));
   ASSERT_TRUE(extinfo.library_fd != -1);
   handle_ = android_dlopen_ext(lib_path, RTLD_NOW, &extinfo);
   ASSERT_DL_NOTNULL(handle_);
   fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
   ASSERT_DL_NOTNULL(f);
   EXPECT_EQ(4, f());
 }

 TEST_F(DlExtTest, Reserved) {
   void* start = mmap(NULL, LIBSIZE, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
                      -1, 0);
   ASSERT_TRUE(start != MAP_FAILED);
   android_dlextinfo extinfo;
   extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS;
   extinfo.reserved_addr = start;
   extinfo.reserved_size = LIBSIZE;
   handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
   ASSERT_DL_NOTNULL(handle_);
   fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
   ASSERT_DL_NOTNULL(f);
   EXPECT_GE(f, start);
   EXPECT_LT(reinterpret_cast<void*>(f),
             reinterpret_cast<char*>(start) + LIBSIZE);
   EXPECT_EQ(4, f());
 }

 TEST_F(DlExtTest, ReservedTooSmall) {
   void* start = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
                      -1, 0);
   ASSERT_TRUE(start != MAP_FAILED);
   android_dlextinfo extinfo;
   extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS;
   extinfo.reserved_addr = start;
   extinfo.reserved_size = PAGE_SIZE;
   handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
   EXPECT_EQ(NULL, handle_);
 }

 TEST_F(DlExtTest, ReservedHint) {
   void* start = mmap(NULL, LIBSIZE, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
                      -1, 0);
   ASSERT_TRUE(start != MAP_FAILED);
   android_dlextinfo extinfo;
   extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS_HINT;
   extinfo.reserved_addr = start;
   extinfo.reserved_size = LIBSIZE;
   handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
   ASSERT_DL_NOTNULL(handle_);
   fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
   ASSERT_DL_NOTNULL(f);
   EXPECT_GE(f, start);
   EXPECT_LT(reinterpret_cast<void*>(f),
             reinterpret_cast<char*>(start) + LIBSIZE);
   EXPECT_EQ(4, f());
 }

 TEST_F(DlExtTest, ReservedHintTooSmall) {
   void* start = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
                      -1, 0);
   ASSERT_TRUE(start != MAP_FAILED);
   android_dlextinfo extinfo;
   extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS_HINT;
   extinfo.reserved_addr = start;
   extinfo.reserved_size = PAGE_SIZE;
   handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
   ASSERT_DL_NOTNULL(handle_);
   fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
   ASSERT_DL_NOTNULL(f);
   EXPECT_TRUE(f < start || (reinterpret_cast<void*>(f) >=
                             reinterpret_cast<char*>(start) + PAGE_SIZE));
   EXPECT_EQ(4, f());
 }

 class DlExtRelroSharingTest : public DlExtTest {
 protected:
   virtual void SetUp() {
     DlExtTest::SetUp();
     void* start = mmap(NULL, LIBSIZE, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
                        -1, 0);
     ASSERT_TRUE(start != MAP_FAILED);
     extinfo_.flags = ANDROID_DLEXT_RESERVED_ADDRESS;
     extinfo_.reserved_addr = start;
     extinfo_.reserved_size = LIBSIZE;
     extinfo_.relro_fd = -1;

     const char* android_data = getenv("ANDROID_DATA");
     ASSERT_TRUE(android_data != NULL);
     snprintf(relro_file_, sizeof(relro_file_), "%s/local/tmp/libdlext_test.relro", android_data);
   }

   virtual void TearDown() {
     DlExtTest::TearDown();
     if (extinfo_.relro_fd != -1) {
       ASSERT_NOERROR(close(extinfo_.relro_fd));
     }
   }

   void CreateRelroFile(const char* lib) {
     int relro_fd = open(relro_file_, O_CREAT | O_RDWR | O_TRUNC, 0644);
     ASSERT_NOERROR(relro_fd);

     pid_t pid = fork();
     if (pid == 0) {
       // child process
       extinfo_.flags |= ANDROID_DLEXT_WRITE_RELRO;
       extinfo_.relro_fd = relro_fd;
       void* handle = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
       if (handle == NULL) {
         fprintf(stderr, "in child: %s\n", dlerror());
         exit(1);
       }
       exit(0);
     }

     // continuing in parent
     ASSERT_NOERROR(close(relro_fd));
     ASSERT_NOERROR(pid);
     int status;
     ASSERT_EQ(pid, waitpid(pid, &status, 0));
     ASSERT_TRUE(WIFEXITED(status));
     ASSERT_EQ(0, WEXITSTATUS(status));

     // reopen file for reading so it can be used
     relro_fd = open(relro_file_, O_RDONLY);
     ASSERT_NOERROR(relro_fd);
     extinfo_.flags |= ANDROID_DLEXT_USE_RELRO;
     extinfo_.relro_fd = relro_fd;
   }

   void TryUsingRelro(const char* lib) {
     handle_ = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
     ASSERT_DL_NOTNULL(handle_);
     fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
     ASSERT_DL_NOTNULL(f);
     EXPECT_EQ(4, f());
   }

   void SpawnChildrenAndMeasurePss(const char* lib, bool share_relro, size_t* pss_out);

   android_dlextinfo extinfo_;
   char relro_file_[PATH_MAX];
 };

 TEST_F(DlExtRelroSharingTest, ChildWritesGoodData) {
   ASSERT_NO_FATAL_FAILURE(CreateRelroFile(LIBNAME));
   ASSERT_NO_FATAL_FAILURE(TryUsingRelro(LIBNAME));
 }

 TEST_F(DlExtRelroSharingTest, ChildWritesNoRelro) {
   ASSERT_NO_FATAL_FAILURE(CreateRelroFile(LIBNAME_NORELRO));
   ASSERT_NO_FATAL_FAILURE(TryUsingRelro(LIBNAME_NORELRO));
 }

 TEST_F(DlExtRelroSharingTest, RelroFileEmpty) {
   int relro_fd = open(relro_file_, O_CREAT | O_RDWR | O_TRUNC, 0644);
   ASSERT_NOERROR(relro_fd);
   ASSERT_NOERROR(close(relro_fd));

   ASSERT_NO_FATAL_FAILURE(TryUsingRelro(LIBNAME));
 }

 TEST_F(DlExtRelroSharingTest, VerifyMemorySaving) {
   ASSERT_NO_FATAL_FAILURE(CreateRelroFile(LIBNAME));
   int relro_fd = open(relro_file_, O_RDONLY);
   ASSERT_NOERROR(relro_fd);
   extinfo_.flags |= ANDROID_DLEXT_USE_RELRO;
   extinfo_.relro_fd = relro_fd;
   int pipefd[2];
   ASSERT_NOERROR(pipe(pipefd));

   size_t without_sharing, with_sharing;
   ASSERT_NO_FATAL_FAILURE(SpawnChildrenAndMeasurePss(LIBNAME, false, &without_sharing));
   ASSERT_NO_FATAL_FAILURE(SpawnChildrenAndMeasurePss(LIBNAME, true, &with_sharing));

   // We expect the sharing to save at least 10% of the total PSS. In practice
   // it saves 40%+ for this test.
   size_t expected_size = without_sharing - (without_sharing/10);
   EXPECT_LT(with_sharing, expected_size);
 }

 void getPss(pid_t pid, size_t* pss_out) {
   pm_kernel_t* kernel;
   ASSERT_EQ(0, pm_kernel_create(&kernel));

   pm_process_t* process;
   ASSERT_EQ(0, pm_process_create(kernel, pid, &process));

   pm_map_t** maps;
   size_t num_maps;
   ASSERT_EQ(0, pm_process_maps(process, &maps, &num_maps));

   size_t total_pss = 0;
   for (size_t i = 0; i < num_maps; i++) {
     pm_memusage_t usage;
     ASSERT_EQ(0, pm_map_usage(maps[i], &usage));
     total_pss += usage.pss;
   }
   *pss_out = total_pss;

   free(maps);
   pm_process_destroy(process);
   pm_kernel_destroy(kernel);
 }

 void DlExtRelroSharingTest::SpawnChildrenAndMeasurePss(const char* lib, bool share_relro,
                                                        size_t* pss_out) {
   const int CHILDREN = 20;

   // Create children
   pid_t childpid[CHILDREN];
   int childpipe[CHILDREN];
   for (int i=0; i<CHILDREN; ++i) {
     char read_buf;
     int child_done_pipe[2], parent_done_pipe[2];
     ASSERT_NOERROR(pipe(child_done_pipe));
     ASSERT_NOERROR(pipe(parent_done_pipe));

     pid_t child = fork();
     if (child == 0) {
       // close the 'wrong' ends of the pipes in the child
       close(child_done_pipe[0]);
       close(parent_done_pipe[1]);

       // open the library
       void* handle;
       if (share_relro) {
         handle = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
       } else {
         handle = dlopen(lib, RTLD_NOW);
       }
       if (handle == NULL) {
         fprintf(stderr, "in child: %s\n", dlerror());
         exit(1);
       }

       // close write end of child_done_pipe to signal the parent that we're done.
       close(child_done_pipe[1]);

       // wait for the parent to close parent_done_pipe, then exit
       read(parent_done_pipe[0], &read_buf, 1);
       exit(0);
     }

     ASSERT_NOERROR(child);

     // close the 'wrong' ends of the pipes in the parent
     close(child_done_pipe[1]);
     close(parent_done_pipe[0]);

     // wait for the child to be done
     read(child_done_pipe[0], &read_buf, 1);
     close(child_done_pipe[0]);

     // save the child's pid and the parent_done_pipe
     childpid[i] = child;
     childpipe[i] = parent_done_pipe[1];
   }

   // Sum the PSS of all the children
   size_t total_pss = 0;
   for (int i=0; i<CHILDREN; ++i) {
     size_t child_pss;
     ASSERT_NO_FATAL_FAILURE(getPss(childpid[i], &child_pss));
     total_pss += child_pss;
   }
   *pss_out = total_pss;

   // Close pipes and wait for children to exit
   for (int i=0; i<CHILDREN; ++i) {
     ASSERT_NOERROR(close(childpipe[i]));
   }
   for (int i=0; i<CHILDREN; ++i) {
     int status;
     ASSERT_EQ(childpid[i], waitpid(childpid[i], &status, 0));
     ASSERT_TRUE(WIFEXITED(status));
     ASSERT_EQ(0, WEXITSTATUS(status));
   }
 }
	/*
	* 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 <gtest/gtest.h>

	#include <dlfcn.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>
	#include <android/dlext.h>
	#include <sys/mman.h>
	#include <sys/types.h>
	#include <sys/wait.h>

	#include <pagemap/pagemap.h>


	#define ASSERT_DL_NOTNULL(ptr) \
	ASSERT_TRUE(ptr != NULL) << "dlerror: " << dlerror()

	#define ASSERT_DL_ZERO(i) \
	ASSERT_EQ(0, i) << "dlerror: " << dlerror()

	#define ASSERT_NOERROR(i) \
	ASSERT_NE(-1, i) << "errno: " << strerror(errno)


	typedef int (*fn)(void);
	#define LIBNAME "libdlext_test.so"
	#define LIBNAME_NORELRO "libdlext_test_norelro.so"
	#define LIBSIZE 1024*1024 // how much address space to reserve for it

	#if defined(__LP64__)
	#define LIBPATH "%s/nativetest64/libdlext_test_fd/libdlext_test_fd.so"
	#else
	#define LIBPATH "%s/nativetest/libdlext_test_fd/libdlext_test_fd.so"
	#endif

	class DlExtTest : public ::testing::Test {
	protected:
	virtual void SetUp() {
	handle_ = NULL;
	// verify that we don't have the library loaded already
	ASSERT_EQ(NULL, dlsym(RTLD_DEFAULT, "getRandomNumber"));
	// call dlerror() to swallow the error, and check it was the one we wanted
	ASSERT_STREQ("undefined symbol: getRandomNumber", dlerror());
	}

	virtual void TearDown() {
	if (handle_ != NULL) {
	ASSERT_DL_ZERO(dlclose(handle_));
	}
	}

	void* handle_;
	};

	TEST_F(DlExtTest, ExtInfoNull) {
	handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, NULL);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_EQ(4, f());
	}

	TEST_F(DlExtTest, ExtInfoNoFlags) {
	android_dlextinfo extinfo;
	extinfo.flags = 0;
	handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_EQ(4, f());
	}

	TEST_F(DlExtTest, ExtInfoUseFd) {
	const char* android_data = getenv("ANDROID_DATA");
	ASSERT_TRUE(android_data != NULL);
	char lib_path[PATH_MAX];
	snprintf(lib_path, sizeof(lib_path), LIBPATH, android_data);

	android_dlextinfo extinfo;
	extinfo.flags = ANDROID_DLEXT_USE_LIBRARY_FD;
	extinfo.library_fd = TEMP_FAILURE_RETRY(open(lib_path, O_RDONLY \| O_CLOEXEC));
	ASSERT_TRUE(extinfo.library_fd != -1);
	handle_ = android_dlopen_ext(lib_path, RTLD_NOW, &extinfo);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_EQ(4, f());
	}

	TEST_F(DlExtTest, Reserved) {
	void* start = mmap(NULL, LIBSIZE, PROT_NONE, MAP_PRIVATE \| MAP_ANONYMOUS,
	-1, 0);
	ASSERT_TRUE(start != MAP_FAILED);
	android_dlextinfo extinfo;
	extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS;
	extinfo.reserved_addr = start;
	extinfo.reserved_size = LIBSIZE;
	handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_GE(f, start);
	EXPECT_LT(reinterpret_cast<void*>(f),
	reinterpret_cast<char*>(start) + LIBSIZE);
	EXPECT_EQ(4, f());
	}

	TEST_F(DlExtTest, ReservedTooSmall) {
	void* start = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE \| MAP_ANONYMOUS,
	-1, 0);
	ASSERT_TRUE(start != MAP_FAILED);
	android_dlextinfo extinfo;
	extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS;
	extinfo.reserved_addr = start;
	extinfo.reserved_size = PAGE_SIZE;
	handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
	EXPECT_EQ(NULL, handle_);
	}

	TEST_F(DlExtTest, ReservedHint) {
	void* start = mmap(NULL, LIBSIZE, PROT_NONE, MAP_PRIVATE \| MAP_ANONYMOUS,
	-1, 0);
	ASSERT_TRUE(start != MAP_FAILED);
	android_dlextinfo extinfo;
	extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS_HINT;
	extinfo.reserved_addr = start;
	extinfo.reserved_size = LIBSIZE;
	handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_GE(f, start);
	EXPECT_LT(reinterpret_cast<void*>(f),
	reinterpret_cast<char*>(start) + LIBSIZE);
	EXPECT_EQ(4, f());
	}

	TEST_F(DlExtTest, ReservedHintTooSmall) {
	void* start = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE \| MAP_ANONYMOUS,
	-1, 0);
	ASSERT_TRUE(start != MAP_FAILED);
	android_dlextinfo extinfo;
	extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS_HINT;
	extinfo.reserved_addr = start;
	extinfo.reserved_size = PAGE_SIZE;
	handle_ = android_dlopen_ext(LIBNAME, RTLD_NOW, &extinfo);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_TRUE(f < start \|\| (reinterpret_cast<void*>(f) >=
	reinterpret_cast<char*>(start) + PAGE_SIZE));
	EXPECT_EQ(4, f());
	}

	class DlExtRelroSharingTest : public DlExtTest {
	protected:
	virtual void SetUp() {
	DlExtTest::SetUp();
	void* start = mmap(NULL, LIBSIZE, PROT_NONE, MAP_PRIVATE \| MAP_ANONYMOUS,
	-1, 0);
	ASSERT_TRUE(start != MAP_FAILED);
	extinfo_.flags = ANDROID_DLEXT_RESERVED_ADDRESS;
	extinfo_.reserved_addr = start;
	extinfo_.reserved_size = LIBSIZE;
	extinfo_.relro_fd = -1;

	const char* android_data = getenv("ANDROID_DATA");
	ASSERT_TRUE(android_data != NULL);
	snprintf(relro_file_, sizeof(relro_file_), "%s/local/tmp/libdlext_test.relro", android_data);
	}

	virtual void TearDown() {
	DlExtTest::TearDown();
	if (extinfo_.relro_fd != -1) {
	ASSERT_NOERROR(close(extinfo_.relro_fd));
	}
	}

	void CreateRelroFile(const char* lib) {
	int relro_fd = open(relro_file_, O_CREAT \| O_RDWR \| O_TRUNC, 0644);
	ASSERT_NOERROR(relro_fd);

	pid_t pid = fork();
	if (pid == 0) {
	// child process
	extinfo_.flags \|= ANDROID_DLEXT_WRITE_RELRO;
	extinfo_.relro_fd = relro_fd;
	void* handle = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
	if (handle == NULL) {
	fprintf(stderr, "in child: %s\n", dlerror());
	exit(1);
	}
	exit(0);
	}

	// continuing in parent
	ASSERT_NOERROR(close(relro_fd));
	ASSERT_NOERROR(pid);
	int status;
	ASSERT_EQ(pid, waitpid(pid, &status, 0));
	ASSERT_TRUE(WIFEXITED(status));
	ASSERT_EQ(0, WEXITSTATUS(status));

	// reopen file for reading so it can be used
	relro_fd = open(relro_file_, O_RDONLY);
	ASSERT_NOERROR(relro_fd);
	extinfo_.flags \|= ANDROID_DLEXT_USE_RELRO;
	extinfo_.relro_fd = relro_fd;
	}

	void TryUsingRelro(const char* lib) {
	handle_ = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
	ASSERT_DL_NOTNULL(handle_);
	fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
	ASSERT_DL_NOTNULL(f);
	EXPECT_EQ(4, f());
	}

	void SpawnChildrenAndMeasurePss(const char* lib, bool share_relro, size_t* pss_out);

	android_dlextinfo extinfo_;
	char relro_file_[PATH_MAX];
	};

	TEST_F(DlExtRelroSharingTest, ChildWritesGoodData) {
	ASSERT_NO_FATAL_FAILURE(CreateRelroFile(LIBNAME));
	ASSERT_NO_FATAL_FAILURE(TryUsingRelro(LIBNAME));
	}

	TEST_F(DlExtRelroSharingTest, ChildWritesNoRelro) {
	ASSERT_NO_FATAL_FAILURE(CreateRelroFile(LIBNAME_NORELRO));
	ASSERT_NO_FATAL_FAILURE(TryUsingRelro(LIBNAME_NORELRO));
	}

	TEST_F(DlExtRelroSharingTest, RelroFileEmpty) {
	int relro_fd = open(relro_file_, O_CREAT \| O_RDWR \| O_TRUNC, 0644);
	ASSERT_NOERROR(relro_fd);
	ASSERT_NOERROR(close(relro_fd));

	ASSERT_NO_FATAL_FAILURE(TryUsingRelro(LIBNAME));
	}

	TEST_F(DlExtRelroSharingTest, VerifyMemorySaving) {
	ASSERT_NO_FATAL_FAILURE(CreateRelroFile(LIBNAME));
	int relro_fd = open(relro_file_, O_RDONLY);
	ASSERT_NOERROR(relro_fd);
	extinfo_.flags \|= ANDROID_DLEXT_USE_RELRO;
	extinfo_.relro_fd = relro_fd;
	int pipefd[2];
	ASSERT_NOERROR(pipe(pipefd));

	size_t without_sharing, with_sharing;
	ASSERT_NO_FATAL_FAILURE(SpawnChildrenAndMeasurePss(LIBNAME, false, &without_sharing));
	ASSERT_NO_FATAL_FAILURE(SpawnChildrenAndMeasurePss(LIBNAME, true, &with_sharing));

	// We expect the sharing to save at least 10% of the total PSS. In practice
	// it saves 40%+ for this test.
	size_t expected_size = without_sharing - (without_sharing/10);
	EXPECT_LT(with_sharing, expected_size);
	}

	void getPss(pid_t pid, size_t* pss_out) {
	pm_kernel_t* kernel;
	ASSERT_EQ(0, pm_kernel_create(&kernel));

	pm_process_t* process;
	ASSERT_EQ(0, pm_process_create(kernel, pid, &process));

	pm_map_t** maps;
	size_t num_maps;
	ASSERT_EQ(0, pm_process_maps(process, &maps, &num_maps));

	size_t total_pss = 0;
	for (size_t i = 0; i < num_maps; i++) {
	pm_memusage_t usage;
	ASSERT_EQ(0, pm_map_usage(maps[i], &usage));
	total_pss += usage.pss;
	}
	*pss_out = total_pss;

	free(maps);
	pm_process_destroy(process);
	pm_kernel_destroy(kernel);
	}

	void DlExtRelroSharingTest::SpawnChildrenAndMeasurePss(const char* lib, bool share_relro,
	size_t* pss_out) {
	const int CHILDREN = 20;

	// Create children
	pid_t childpid[CHILDREN];
	int childpipe[CHILDREN];
	for (int i=0; i<CHILDREN; ++i) {
	char read_buf;
	int child_done_pipe[2], parent_done_pipe[2];
	ASSERT_NOERROR(pipe(child_done_pipe));
	ASSERT_NOERROR(pipe(parent_done_pipe));

	pid_t child = fork();
	if (child == 0) {
	// close the 'wrong' ends of the pipes in the child
	close(child_done_pipe[0]);
	close(parent_done_pipe[1]);

	// open the library
	void* handle;
	if (share_relro) {
	handle = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
	} else {
	handle = dlopen(lib, RTLD_NOW);
	}
	if (handle == NULL) {
	fprintf(stderr, "in child: %s\n", dlerror());
	exit(1);
	}

	// close write end of child_done_pipe to signal the parent that we're done.
	close(child_done_pipe[1]);

	// wait for the parent to close parent_done_pipe, then exit
	read(parent_done_pipe[0], &read_buf, 1);
	exit(0);
	}

	ASSERT_NOERROR(child);

	// close the 'wrong' ends of the pipes in the parent
	close(child_done_pipe[1]);
	close(parent_done_pipe[0]);

	// wait for the child to be done
	read(child_done_pipe[0], &read_buf, 1);
	close(child_done_pipe[0]);

	// save the child's pid and the parent_done_pipe
	childpid[i] = child;
	childpipe[i] = parent_done_pipe[1];
	}

	// Sum the PSS of all the children
	size_t total_pss = 0;
	for (int i=0; i<CHILDREN; ++i) {
	size_t child_pss;
	ASSERT_NO_FATAL_FAILURE(getPss(childpid[i], &child_pss));
	total_pss += child_pss;
	}
	*pss_out = total_pss;

	// Close pipes and wait for children to exit
	for (int i=0; i<CHILDREN; ++i) {
	ASSERT_NOERROR(close(childpipe[i]));
	}
	for (int i=0; i<CHILDREN; ++i) {
	int status;
	ASSERT_EQ(childpid[i], waitpid(childpid[i], &status, 0));
	ASSERT_TRUE(WIFEXITED(status));
	ASSERT_EQ(0, WEXITSTATUS(status));
	}
	}