libcutils/ashmem_test.cpp - platform/system/core - Git at Google

 /*
  * Copyright (C) 2016 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 <errno.h>
 #include <linux/fs.h>
 #include <stdint.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <unistd.h>

 #include <vector>

 #include <android-base/macros.h>
 #include <android-base/unique_fd.h>
 #include <cutils/ashmem.h>
 #include <gtest/gtest.h>

 #include "ashmem-internal.h"

 using android::base::unique_fd;

 static void TestCreateRegion(size_t size, unique_fd &fd, int prot, const char *name=nullptr) {
     fd = unique_fd(ashmem_create_region(name, size));
     ASSERT_TRUE(fd >= 0);
     ASSERT_TRUE(ashmem_valid(fd));
     ASSERT_EQ(size, static_cast<size_t>(ashmem_get_size_region(fd)));
     ASSERT_EQ(0, ashmem_set_prot_region(fd, prot));

     // We've been inconsistent historically about whether or not these file
     // descriptors were CLOEXEC. Make sure we're consistent going forward.
     // https://issuetracker.google.com/165667331
     ASSERT_EQ(FD_CLOEXEC, (fcntl(fd, F_GETFD) & FD_CLOEXEC));
 }

 static void TestMmap(const unique_fd& fd, size_t size, int prot, void** region, off_t off = 0) {
     ASSERT_TRUE(fd >= 0);
     ASSERT_TRUE(ashmem_valid(fd));
     *region = mmap(nullptr, size, prot, MAP_SHARED, fd, off);
     ASSERT_NE(MAP_FAILED, *region);
 }

 static void TestProtDenied(const unique_fd &fd, size_t size, int prot) {
     ASSERT_TRUE(fd >= 0);
     ASSERT_TRUE(ashmem_valid(fd));
     EXPECT_EQ(MAP_FAILED, mmap(nullptr, size, prot, MAP_SHARED, fd, 0));
 }

 static void TestProtIs(const unique_fd& fd, int prot) {
     ASSERT_TRUE(fd >= 0);
     ASSERT_TRUE(ashmem_valid(fd));
     EXPECT_EQ(prot, ioctl(fd, ASHMEM_GET_PROT_MASK));
 }

 static void FillData(std::vector<uint8_t>& data) {
     for (size_t i = 0; i < data.size(); i++) {
         data[i] = i & 0xFF;
     }
 }

 static void waitForChildProcessExit(pid_t pid) {
     int exitStatus;
     pid_t childPid = waitpid(pid, &exitStatus, 0);

     ASSERT_GT(childPid, 0);
     ASSERT_TRUE(WIFEXITED(exitStatus));
     ASSERT_EQ(0, WEXITSTATUS(exitStatus));
 }

 static void ForkTest(const unique_fd &fd, size_t size) {
     void* region1 = nullptr;
     std::vector<uint8_t> data(size);
     FillData(data);

     ASSERT_NO_FATAL_FAILURE(TestMmap(fd, size, PROT_READ | PROT_WRITE, &region1));

     memcpy(region1, data.data(), size);
     ASSERT_EQ(0, memcmp(region1, data.data(), size));
     EXPECT_EQ(0, munmap(region1, size));


     pid_t pid = fork();
     if (!pid) {
         if (!ashmem_valid(fd)) {
             _exit(3);
         }

         void *region2 = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
         if (region2 == MAP_FAILED) {
             _exit(1);
         } else if (memcmp(region2, data.data(), size) != 0){
             _exit(2);
         }

         // Clear the ashmem buffer here to ensure that updates to the contents
         // of the buffer are visible across processes with a reference to the
         // buffer.
         memset(region2, 0, size);
         munmap(region2, size);
         _exit(0);
     } else {
         ASSERT_GT(pid, 0);
         ASSERT_NO_FATAL_FAILURE(waitForChildProcessExit(pid));
     }

     memset(data.data(), 0, size);
     void *region2;
     ASSERT_NO_FATAL_FAILURE(TestMmap(fd, size, PROT_READ | PROT_WRITE, &region2));
     ASSERT_EQ(0, memcmp(region2, data.data(), size));
     EXPECT_EQ(0, munmap(region2, size));
 }

 static void FileOperationsTest(const unique_fd &fd, size_t size) {
     void* region = nullptr;

     const size_t pageSize = getpagesize();
     const size_t dataSize = pageSize * 2;
     const size_t holeSize = pageSize;
     ASSERT_NO_FATAL_FAILURE(TestMmap(fd, dataSize, PROT_READ | PROT_WRITE, &region, holeSize));

     std::vector<uint8_t> data(dataSize);
     FillData(data);
     memcpy(region, data.data(), dataSize);

     const off_t dataStart = holeSize;
     const off_t dataEnd = dataStart + dataSize;

     // The sequence of seeks below looks something like this:
     //
     // [    ][data][data][    ]
     // --^                          lseek(99, SEEK_SET)
     //   ------^                    lseek(dataStart, SEEK_CUR)
     // ------^                      lseek(0, SEEK_DATA)
     //       ------------^          lseek(dataStart, SEEK_HOLE)
     //                      ^--     lseek(-99, SEEK_END)
     //                ^------       lseek(-dataStart, SEEK_CUR)
     const struct {
         // lseek() parameters
         off_t offset;
         int whence;
         // Expected lseek() return value
         off_t ret;
     } seeks[] = {
             {99, SEEK_SET, 99},
             {dataStart, SEEK_CUR, dataStart + 99},
             {0, SEEK_DATA, dataStart},
             {dataStart, SEEK_HOLE, dataEnd},
             {-99, SEEK_END, static_cast<off_t>(size) - 99},
             {-dataStart, SEEK_CUR, dataEnd - 99},
     };
     for (const auto& cfg : seeks) {
         errno = 0;
         ASSERT_TRUE(ashmem_valid(fd));
         auto off = lseek(fd, cfg.offset, cfg.whence);
         ASSERT_EQ(cfg.ret, off) << "lseek(" << cfg.offset << ", " << cfg.whence << ") failed"
                                 << (errno ? ": " : "") << (errno ? strerror(errno) : "");

         if (off >= dataStart && off < dataEnd) {
             off_t dataOff = off - dataStart;
             ssize_t readSize = dataSize - dataOff;
             uint8_t buf[readSize];

             ASSERT_EQ(readSize, TEMP_FAILURE_RETRY(read(fd, buf, readSize)));
             EXPECT_EQ(0, memcmp(buf, &data[dataOff], readSize));
         }
     }

     EXPECT_EQ(0, munmap(region, dataSize));
 }

 static void ProtTestROBuffer(const unique_fd &fd, size_t size) {
     void *region;

     TestProtDenied(fd, size, PROT_WRITE);
     TestProtIs(fd, PROT_READ | PROT_EXEC);
     ASSERT_NO_FATAL_FAILURE(TestMmap(fd, size, PROT_READ, &region));
     EXPECT_EQ(0, munmap(region, size));
 }

 static void ProtTestRWBuffer(const unique_fd &fd, size_t size) {
     TestProtIs(fd, PROT_READ | PROT_WRITE | PROT_EXEC);
     ASSERT_EQ(0, ashmem_set_prot_region(fd, PROT_READ | PROT_EXEC));
     errno = 0;
     ASSERT_EQ(-1, ashmem_set_prot_region(fd, PROT_READ | PROT_WRITE |
                                          PROT_EXEC))
         << "kernel shouldn't allow adding protection bits";
     EXPECT_EQ(EINVAL, errno);
     TestProtIs(fd, PROT_READ | PROT_EXEC);
     TestProtDenied(fd, size, PROT_WRITE);
 }

 static void ForkProtTest(const unique_fd &fd, size_t size) {
     pid_t pid = fork();
     if (!pid) {
         // Change buffer mapping permissions to read-only to ensure that
         // updates to the buffer's mapping permissions are visible across
         // processes that reference the buffer.
         if (!ashmem_valid(fd)) {
             _exit(3);
         } else if (ashmem_set_prot_region(fd, PROT_READ) == -1) {
             _exit(1);
         }
         _exit(0);
     } else {
         ASSERT_GT(pid, 0);
         ASSERT_NO_FATAL_FAILURE(waitForChildProcessExit(pid));
     }

     ASSERT_NO_FATAL_FAILURE(TestProtDenied(fd, size, PROT_WRITE));
 }

 static void ForkMultiRegionTest(unique_fd fds[], int nRegions, size_t size) {
     std::vector<uint8_t> data(size);
     FillData(data);

     for (int i = 0; i < nRegions; i++) {
         void* region = nullptr;
         ASSERT_NO_FATAL_FAILURE(TestMmap(fds[i], size, PROT_READ | PROT_WRITE, &region));
         memcpy(region, data.data(), size);
         ASSERT_EQ(0, memcmp(region, data.data(), size));
         EXPECT_EQ(0, munmap(region, size));
     }

     pid_t pid = fork();
     if (!pid) {
         // Clear each ashmem buffer in the context of the child process to
         // ensure that the updates are visible to the parent process later.
         for (int i = 0; i < nRegions; i++) {
             if (!ashmem_valid(fds[i])) {
                 _exit(3);
             }
             void *region = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fds[i], 0);
             if (region == MAP_FAILED) {
                 _exit(1);
             }
             if (memcmp(region, data.data(), size) != 0) {
                 munmap(region, size);
                 _exit(2);
             }
             memset(region, 0, size);
             munmap(region, size);
         }
         _exit(0);
     } else {
         ASSERT_GT(pid, 0);
         ASSERT_NO_FATAL_FAILURE(waitForChildProcessExit(pid));
     }

     memset(data.data(), 0, size);
     for (int i = 0; i < nRegions; i++) {
         void *region;
         ASSERT_NO_FATAL_FAILURE(TestMmap(fds[i], size, PROT_READ | PROT_WRITE, &region));
         ASSERT_EQ(0, memcmp(region, data.data(), size));
         EXPECT_EQ(0, munmap(region, size));
     }

 }

 static void GetNameAshmemTest(const std::string &name) {
     // We use __ashmem_open() to guarantee we get an ashmem fd. We need to do this since ashmem and
     // memfd have different maximum name lengths.
     unique_fd fd(__ashmem_open());
     ASSERT_TRUE(fd >= 0);

     ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_NAME, name.c_str()));

     char retName[ASHMEM_NAME_LEN];
     ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, retName));
     ASSERT_STREQ(retName, name.substr(0, ASHMEM_NAME_LEN - 1).c_str());
 }

 TEST(AshmemTest, ForkTest) {
     const size_t size = getpagesize();
     unique_fd fd;

     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ | PROT_WRITE));
     ASSERT_NO_FATAL_FAILURE(ForkTest(fd, size));
 }

 TEST(AshmemTest, FileOperationsTest) {
     const size_t pageSize = getpagesize();
     // Allocate a 4-page buffer, but leave page-sized holes on either side in
     // the test.
     const size_t size = pageSize * 4;
     unique_fd fd;

     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ | PROT_WRITE));
     ASSERT_NO_FATAL_FAILURE(FileOperationsTest(fd, size));
 }

 TEST(AshmemTest, ProtTest) {
     unique_fd fd;
     const size_t size = getpagesize();

     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ | PROT_EXEC));
     ASSERT_NO_FATAL_FAILURE(ProtTestROBuffer(fd, size));

     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ | PROT_WRITE | PROT_EXEC));
     ASSERT_NO_FATAL_FAILURE(ProtTestRWBuffer(fd, size));
 }

 TEST(AshmemTest, ForkProtTest) {
     unique_fd fd;
     const size_t size = getpagesize();

     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ | PROT_WRITE));
     ASSERT_NO_FATAL_FAILURE(ForkProtTest(fd, size));
 }

 TEST(AshmemTest, ForkMultiRegionTest) {
     const size_t size = getpagesize();
     constexpr int nRegions = 16;
     unique_fd fds[nRegions];

     for (int i = 0; i < nRegions; i++) {
         ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fds[i], PROT_READ | PROT_WRITE));
     }

     ASSERT_NO_FATAL_FAILURE(ForkMultiRegionTest(fds, nRegions, size));
 }

 // We don't run a similar test as part of the AshmemTestMemfdAshmemCompat tests, since the SET_NAME
 // ioctl is not supported.
 TEST(AshmemTest, SetNameKernelAccessTest) {
     size_t pageSize = getpagesize();
     // We use mmap to get a page-aligned area, since the smallest accessibility granule is a page.
     // We also allocate 2 pages worth of virtual address space so that when we unmap the 2nd page
     // we can be sure we've created a hole in the process' address space.
     void *testArea = mmap(nullptr, 2 * pageSize, PROT_READ | PROT_WRITE,
                           MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
     ASSERT_NE(testArea, MAP_FAILED);

     // Create a hole in the address space to catch accesses beyond the string from the kernel, which
     // would cause TestCreateRegion() to fail.
     char *secondPage = static_cast<char *>(testArea) + pageSize;
     ASSERT_EQ(0, munmap(secondPage, pageSize));

     // Write the name such that even if the implementation of the SET_NAME ioctl is always reading
     // ASHMEM_NAME_LEN bytes, it is guaranteed to succeed given the start address of "test-buf".
     char *name = secondPage - ASHMEM_NAME_LEN;
     strcpy(name, "test-buf");

     unique_fd fd;
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(pageSize, fd, PROT_READ | PROT_WRITE, name));

     unique_fd fd2;
     // This should not fail either, as "est-buf" is also a valid string, but a broken
     // implementation of the SET_NAME ioctl can blindly read ASHMEM_NAME_LEN bytes each time,
     // instead of searching for the NUL terminating byte.
     //
     // If it fails, it's because the kernel accessed the unmapped region.
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(pageSize, fd2, PROT_READ | PROT_WRITE, &name[1]));

     ASSERT_EQ(0, munmap(testArea, pageSize));
 }

 TEST(AshmemTest, GetLongNameAshmemTests) {
     std::string longName(ASHMEM_NAME_LEN - 1, 'A');
     ASSERT_NO_FATAL_FAILURE(GetNameAshmemTest(longName));

     longName.append(1, 'A');
     // This should not fail because ashmem will just truncate the name if it is too long.
     ASSERT_NO_FATAL_FAILURE(GetNameAshmemTest(longName));
 }

 class AshmemTestMemfdAshmemCompat : public ::testing::Test {
  protected:
   void SetUp() override {
     if (!has_memfd_support()){
         GTEST_SKIP() << "No memfd support; skipping memfd-ashmem compat tests";
     }
   }
 };

 TEST_F(AshmemTestMemfdAshmemCompat, SetNameTest) {
     unique_fd fd;

     // ioctl() should fail, since memfd names cannot be changed after the buffer has been created.
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));
     ASSERT_LT(ioctl(fd, ASHMEM_SET_NAME, "invalid-command"), 0);
 }

 TEST_F(AshmemTestMemfdAshmemCompat, GetNameTest) {
     unique_fd fd;
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));

     char testBuf[ASHMEM_NAME_LEN];
     ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, &testBuf));
     // ashmem_create_region(nullptr, ...) creates memfds with the name "none".
     ASSERT_STREQ(testBuf, "none");
 }

 TEST_F(AshmemTestMemfdAshmemCompat, GetLongNameMemfdTests) {
     // memfd names have a maximum length of 249 bytes excluding the NUL terminating byte.
     // See: https://man7.org/linux/man-pages/man2/memfd_create.2.html
     const size_t max_memfd_name_len = 249;
     std::string longName(max_memfd_name_len, 'A');
     size_t pageSize = getpagesize();
     unique_fd fd;
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(pageSize, fd, PROT_READ | PROT_WRITE | PROT_EXEC,
                                              longName.c_str()));

     char retName[max_memfd_name_len + 1];
     ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, retName));
     ASSERT_STREQ(retName, longName.c_str());

     longName.append(1, 'A');
     // Use ashmem_create_region() since it should fail, since the string is now over the maximum
     // length.
     ASSERT_LT(ashmem_create_region(longName.c_str(), pageSize), 0);
 }

 TEST_F(AshmemTestMemfdAshmemCompat, SetSizeTest) {
     unique_fd fd;

     // ioctl() should fail, since libcutils sets and seals the buffer size after creating it.
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));
     ASSERT_LT(ioctl(fd, ASHMEM_SET_SIZE, 2 * getpagesize()), 0);
 }

 TEST_F(AshmemTestMemfdAshmemCompat, GetSizeTest) {
     unique_fd fd;
     size_t bufSize = getpagesize();

     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(bufSize, fd, PROT_READ | PROT_WRITE | PROT_EXEC));
     ASSERT_EQ(static_cast<int>(bufSize), ioctl(fd, ASHMEM_GET_SIZE, 0));
 }

 TEST_F(AshmemTestMemfdAshmemCompat, ProtMaskTest) {
     unique_fd fd;
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));

     // We can only change PROT_WRITE for memfds since memfd implements ashmem's prot_mask through
     // file seals, and only write seals exist.
     //
     // All memfd files start off as being writable (i.e. PROT_WRITE is part of the prot_mask).
     // Test to ensure that the implementation only clears the PROT_WRITE bit when requested.
     ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_PROT_MASK, PROT_READ | PROT_WRITE | PROT_EXEC));
     int prot = ioctl(fd, ASHMEM_GET_PROT_MASK, 0);
     ASSERT_NE(prot, -1);
     ASSERT_TRUE(prot & PROT_WRITE) << prot;

     ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_PROT_MASK, PROT_READ | PROT_EXEC));
     prot = ioctl(fd, ASHMEM_GET_PROT_MASK, 0);
     ASSERT_NE(prot, -1);
     ASSERT_TRUE(!(prot & PROT_WRITE)) << prot;

     // The shim layer should implement clearing PROT_WRITE via file seals, so check the file
     // seals to ensure that F_SEAL_FUTURE_WRITE is set.
     int seals = fcntl(fd, F_GET_SEALS, 0);
     ASSERT_NE(seals, -1);
     ASSERT_TRUE(seals & F_SEAL_FUTURE_WRITE) << seals;

     // Similarly, ensure that file seals affect prot_mask
     unique_fd fd2;
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd2, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));
     ASSERT_EQ(0, fcntl(fd2, F_ADD_SEALS, F_SEAL_FUTURE_WRITE));
     prot = ioctl(fd2, ASHMEM_GET_PROT_MASK, 0);
     ASSERT_NE(prot, -1);
     ASSERT_TRUE(!(prot & PROT_WRITE)) << prot;

     // And finally, ensure that adding back permissions fails
     ASSERT_LT(ioctl(fd2, ASHMEM_SET_PROT_MASK, PROT_READ | PROT_WRITE | PROT_EXEC), 0);
 }

 TEST_F(AshmemTestMemfdAshmemCompat, FileIDTest) {
     unique_fd fd;
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));

     unsigned long ino;
     ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_FILE_ID, &ino));
     struct stat st;
     ASSERT_EQ(0, fstat(fd, &st));
     ASSERT_EQ(ino, st.st_ino);
 }

 TEST_F(AshmemTestMemfdAshmemCompat, UnpinningTest) {
     unique_fd fd;
     size_t bufSize = getpagesize();
     ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ | PROT_WRITE |
                                                                 PROT_EXEC));

     struct ashmem_pin pin = {
         .offset = 0,
         .len = static_cast<uint32_t>(bufSize),
     };
     ASSERT_EQ(0, ioctl(fd, ASHMEM_UNPIN, &pin));
     // ASHMEM_UNPIN should just be a nop
     ASSERT_EQ(ASHMEM_IS_PINNED, ioctl(fd, ASHMEM_GET_PIN_STATUS, 0));

     // This shouldn't do anything; when we pin the page, it shouldn't have been purged.
     ASSERT_EQ(0, ioctl(fd, ASHMEM_PURGE_ALL_CACHES, 0));
     ASSERT_EQ(ASHMEM_NOT_PURGED, ioctl(fd, ASHMEM_PIN, &pin));
 }
	/*
	* Copyright (C) 2016 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 <errno.h>
	#include <linux/fs.h>
	#include <stdint.h>
	#include <string.h>
	#include <sys/mman.h>
	#include <sys/types.h>
	#include <unistd.h>

	#include <vector>

	#include <android-base/macros.h>
	#include <android-base/unique_fd.h>
	#include <cutils/ashmem.h>
	#include <gtest/gtest.h>

	#include "ashmem-internal.h"

	using android::base::unique_fd;

	static void TestCreateRegion(size_t size, unique_fd &fd, int prot, const char *name=nullptr) {
	fd = unique_fd(ashmem_create_region(name, size));
	ASSERT_TRUE(fd >= 0);
	ASSERT_TRUE(ashmem_valid(fd));
	ASSERT_EQ(size, static_cast<size_t>(ashmem_get_size_region(fd)));
	ASSERT_EQ(0, ashmem_set_prot_region(fd, prot));

	// We've been inconsistent historically about whether or not these file
	// descriptors were CLOEXEC. Make sure we're consistent going forward.
	// https://issuetracker.google.com/165667331
	ASSERT_EQ(FD_CLOEXEC, (fcntl(fd, F_GETFD) & FD_CLOEXEC));
	}

	static void TestMmap(const unique_fd& fd, size_t size, int prot, void** region, off_t off = 0) {
	ASSERT_TRUE(fd >= 0);
	ASSERT_TRUE(ashmem_valid(fd));
	*region = mmap(nullptr, size, prot, MAP_SHARED, fd, off);
	ASSERT_NE(MAP_FAILED, *region);
	}

	static void TestProtDenied(const unique_fd &fd, size_t size, int prot) {
	ASSERT_TRUE(fd >= 0);
	ASSERT_TRUE(ashmem_valid(fd));
	EXPECT_EQ(MAP_FAILED, mmap(nullptr, size, prot, MAP_SHARED, fd, 0));
	}

	static void TestProtIs(const unique_fd& fd, int prot) {
	ASSERT_TRUE(fd >= 0);
	ASSERT_TRUE(ashmem_valid(fd));
	EXPECT_EQ(prot, ioctl(fd, ASHMEM_GET_PROT_MASK));
	}

	static void FillData(std::vector<uint8_t>& data) {
	for (size_t i = 0; i < data.size(); i++) {
	data[i] = i & 0xFF;
	}
	}

	static void waitForChildProcessExit(pid_t pid) {
	int exitStatus;
	pid_t childPid = waitpid(pid, &exitStatus, 0);

	ASSERT_GT(childPid, 0);
	ASSERT_TRUE(WIFEXITED(exitStatus));
	ASSERT_EQ(0, WEXITSTATUS(exitStatus));
	}

	static void ForkTest(const unique_fd &fd, size_t size) {
	void* region1 = nullptr;
	std::vector<uint8_t> data(size);
	FillData(data);

	ASSERT_NO_FATAL_FAILURE(TestMmap(fd, size, PROT_READ \| PROT_WRITE, &region1));

	memcpy(region1, data.data(), size);
	ASSERT_EQ(0, memcmp(region1, data.data(), size));
	EXPECT_EQ(0, munmap(region1, size));


	pid_t pid = fork();
	if (!pid) {
	if (!ashmem_valid(fd)) {
	_exit(3);
	}

	void *region2 = mmap(nullptr, size, PROT_READ \| PROT_WRITE, MAP_SHARED, fd, 0);
	if (region2 == MAP_FAILED) {
	_exit(1);
	} else if (memcmp(region2, data.data(), size) != 0){
	_exit(2);
	}

	// Clear the ashmem buffer here to ensure that updates to the contents
	// of the buffer are visible across processes with a reference to the
	// buffer.
	memset(region2, 0, size);
	munmap(region2, size);
	_exit(0);
	} else {
	ASSERT_GT(pid, 0);
	ASSERT_NO_FATAL_FAILURE(waitForChildProcessExit(pid));
	}

	memset(data.data(), 0, size);
	void *region2;
	ASSERT_NO_FATAL_FAILURE(TestMmap(fd, size, PROT_READ \| PROT_WRITE, &region2));
	ASSERT_EQ(0, memcmp(region2, data.data(), size));
	EXPECT_EQ(0, munmap(region2, size));
	}

	static void FileOperationsTest(const unique_fd &fd, size_t size) {
	void* region = nullptr;

	const size_t pageSize = getpagesize();
	const size_t dataSize = pageSize * 2;
	const size_t holeSize = pageSize;
	ASSERT_NO_FATAL_FAILURE(TestMmap(fd, dataSize, PROT_READ \| PROT_WRITE, &region, holeSize));

	std::vector<uint8_t> data(dataSize);
	FillData(data);
	memcpy(region, data.data(), dataSize);

	const off_t dataStart = holeSize;
	const off_t dataEnd = dataStart + dataSize;

	// The sequence of seeks below looks something like this:
	//
	// [ ][data][data][ ]
	// --^ lseek(99, SEEK_SET)
	// ------^ lseek(dataStart, SEEK_CUR)
	// ------^ lseek(0, SEEK_DATA)
	// ------------^ lseek(dataStart, SEEK_HOLE)
	// ^-- lseek(-99, SEEK_END)
	// ^------ lseek(-dataStart, SEEK_CUR)
	const struct {
	// lseek() parameters
	off_t offset;
	int whence;
	// Expected lseek() return value
	off_t ret;
	} seeks[] = {
	{99, SEEK_SET, 99},
	{dataStart, SEEK_CUR, dataStart + 99},
	{0, SEEK_DATA, dataStart},
	{dataStart, SEEK_HOLE, dataEnd},
	{-99, SEEK_END, static_cast<off_t>(size) - 99},
	{-dataStart, SEEK_CUR, dataEnd - 99},
	};
	for (const auto& cfg : seeks) {
	errno = 0;
	ASSERT_TRUE(ashmem_valid(fd));
	auto off = lseek(fd, cfg.offset, cfg.whence);
	ASSERT_EQ(cfg.ret, off) << "lseek(" << cfg.offset << ", " << cfg.whence << ") failed"
	<< (errno ? ": " : "") << (errno ? strerror(errno) : "");

	if (off >= dataStart && off < dataEnd) {
	off_t dataOff = off - dataStart;
	ssize_t readSize = dataSize - dataOff;
	uint8_t buf[readSize];

	ASSERT_EQ(readSize, TEMP_FAILURE_RETRY(read(fd, buf, readSize)));
	EXPECT_EQ(0, memcmp(buf, &data[dataOff], readSize));
	}
	}

	EXPECT_EQ(0, munmap(region, dataSize));
	}

	static void ProtTestROBuffer(const unique_fd &fd, size_t size) {
	void *region;

	TestProtDenied(fd, size, PROT_WRITE);
	TestProtIs(fd, PROT_READ \| PROT_EXEC);
	ASSERT_NO_FATAL_FAILURE(TestMmap(fd, size, PROT_READ, &region));
	EXPECT_EQ(0, munmap(region, size));
	}

	static void ProtTestRWBuffer(const unique_fd &fd, size_t size) {
	TestProtIs(fd, PROT_READ \| PROT_WRITE \| PROT_EXEC);
	ASSERT_EQ(0, ashmem_set_prot_region(fd, PROT_READ \| PROT_EXEC));
	errno = 0;
	ASSERT_EQ(-1, ashmem_set_prot_region(fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC))
	<< "kernel shouldn't allow adding protection bits";
	EXPECT_EQ(EINVAL, errno);
	TestProtIs(fd, PROT_READ \| PROT_EXEC);
	TestProtDenied(fd, size, PROT_WRITE);
	}

	static void ForkProtTest(const unique_fd &fd, size_t size) {
	pid_t pid = fork();
	if (!pid) {
	// Change buffer mapping permissions to read-only to ensure that
	// updates to the buffer's mapping permissions are visible across
	// processes that reference the buffer.
	if (!ashmem_valid(fd)) {
	_exit(3);
	} else if (ashmem_set_prot_region(fd, PROT_READ) == -1) {
	_exit(1);
	}
	_exit(0);
	} else {
	ASSERT_GT(pid, 0);
	ASSERT_NO_FATAL_FAILURE(waitForChildProcessExit(pid));
	}

	ASSERT_NO_FATAL_FAILURE(TestProtDenied(fd, size, PROT_WRITE));
	}

	static void ForkMultiRegionTest(unique_fd fds[], int nRegions, size_t size) {
	std::vector<uint8_t> data(size);
	FillData(data);

	for (int i = 0; i < nRegions; i++) {
	void* region = nullptr;
	ASSERT_NO_FATAL_FAILURE(TestMmap(fds[i], size, PROT_READ \| PROT_WRITE, &region));
	memcpy(region, data.data(), size);
	ASSERT_EQ(0, memcmp(region, data.data(), size));
	EXPECT_EQ(0, munmap(region, size));
	}

	pid_t pid = fork();
	if (!pid) {
	// Clear each ashmem buffer in the context of the child process to
	// ensure that the updates are visible to the parent process later.
	for (int i = 0; i < nRegions; i++) {
	if (!ashmem_valid(fds[i])) {
	_exit(3);
	}
	void *region = mmap(nullptr, size, PROT_READ \| PROT_WRITE, MAP_SHARED, fds[i], 0);
	if (region == MAP_FAILED) {
	_exit(1);
	}
	if (memcmp(region, data.data(), size) != 0) {
	munmap(region, size);
	_exit(2);
	}
	memset(region, 0, size);
	munmap(region, size);
	}
	_exit(0);
	} else {
	ASSERT_GT(pid, 0);
	ASSERT_NO_FATAL_FAILURE(waitForChildProcessExit(pid));
	}

	memset(data.data(), 0, size);
	for (int i = 0; i < nRegions; i++) {
	void *region;
	ASSERT_NO_FATAL_FAILURE(TestMmap(fds[i], size, PROT_READ \| PROT_WRITE, &region));
	ASSERT_EQ(0, memcmp(region, data.data(), size));
	EXPECT_EQ(0, munmap(region, size));
	}

	}

	static void GetNameAshmemTest(const std::string &name) {
	// We use __ashmem_open() to guarantee we get an ashmem fd. We need to do this since ashmem and
	// memfd have different maximum name lengths.
	unique_fd fd(__ashmem_open());
	ASSERT_TRUE(fd >= 0);

	ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_NAME, name.c_str()));

	char retName[ASHMEM_NAME_LEN];
	ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, retName));
	ASSERT_STREQ(retName, name.substr(0, ASHMEM_NAME_LEN - 1).c_str());
	}

	TEST(AshmemTest, ForkTest) {
	const size_t size = getpagesize();
	unique_fd fd;

	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ \| PROT_WRITE));
	ASSERT_NO_FATAL_FAILURE(ForkTest(fd, size));
	}

	TEST(AshmemTest, FileOperationsTest) {
	const size_t pageSize = getpagesize();
	// Allocate a 4-page buffer, but leave page-sized holes on either side in
	// the test.
	const size_t size = pageSize * 4;
	unique_fd fd;

	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ \| PROT_WRITE));
	ASSERT_NO_FATAL_FAILURE(FileOperationsTest(fd, size));
	}

	TEST(AshmemTest, ProtTest) {
	unique_fd fd;
	const size_t size = getpagesize();

	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ \| PROT_EXEC));
	ASSERT_NO_FATAL_FAILURE(ProtTestROBuffer(fd, size));

	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ \| PROT_WRITE \| PROT_EXEC));
	ASSERT_NO_FATAL_FAILURE(ProtTestRWBuffer(fd, size));
	}

	TEST(AshmemTest, ForkProtTest) {
	unique_fd fd;
	const size_t size = getpagesize();

	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fd, PROT_READ \| PROT_WRITE));
	ASSERT_NO_FATAL_FAILURE(ForkProtTest(fd, size));
	}

	TEST(AshmemTest, ForkMultiRegionTest) {
	const size_t size = getpagesize();
	constexpr int nRegions = 16;
	unique_fd fds[nRegions];

	for (int i = 0; i < nRegions; i++) {
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(size, fds[i], PROT_READ \| PROT_WRITE));
	}

	ASSERT_NO_FATAL_FAILURE(ForkMultiRegionTest(fds, nRegions, size));
	}

	// We don't run a similar test as part of the AshmemTestMemfdAshmemCompat tests, since the SET_NAME
	// ioctl is not supported.
	TEST(AshmemTest, SetNameKernelAccessTest) {
	size_t pageSize = getpagesize();
	// We use mmap to get a page-aligned area, since the smallest accessibility granule is a page.
	// We also allocate 2 pages worth of virtual address space so that when we unmap the 2nd page
	// we can be sure we've created a hole in the process' address space.
	void testArea = mmap(nullptr, 2 pageSize, PROT_READ \| PROT_WRITE,
	MAP_ANONYMOUS \| MAP_PRIVATE, -1, 0);
	ASSERT_NE(testArea, MAP_FAILED);

	// Create a hole in the address space to catch accesses beyond the string from the kernel, which
	// would cause TestCreateRegion() to fail.
	char secondPage = static_cast<char >(testArea) + pageSize;
	ASSERT_EQ(0, munmap(secondPage, pageSize));

	// Write the name such that even if the implementation of the SET_NAME ioctl is always reading
	// ASHMEM_NAME_LEN bytes, it is guaranteed to succeed given the start address of "test-buf".
	char *name = secondPage - ASHMEM_NAME_LEN;
	strcpy(name, "test-buf");

	unique_fd fd;
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(pageSize, fd, PROT_READ \| PROT_WRITE, name));

	unique_fd fd2;
	// This should not fail either, as "est-buf" is also a valid string, but a broken
	// implementation of the SET_NAME ioctl can blindly read ASHMEM_NAME_LEN bytes each time,
	// instead of searching for the NUL terminating byte.
	//
	// If it fails, it's because the kernel accessed the unmapped region.
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(pageSize, fd2, PROT_READ \| PROT_WRITE, &name[1]));

	ASSERT_EQ(0, munmap(testArea, pageSize));
	}

	TEST(AshmemTest, GetLongNameAshmemTests) {
	std::string longName(ASHMEM_NAME_LEN - 1, 'A');
	ASSERT_NO_FATAL_FAILURE(GetNameAshmemTest(longName));

	longName.append(1, 'A');
	// This should not fail because ashmem will just truncate the name if it is too long.
	ASSERT_NO_FATAL_FAILURE(GetNameAshmemTest(longName));
	}

	class AshmemTestMemfdAshmemCompat : public ::testing::Test {
	protected:
	void SetUp() override {
	if (!has_memfd_support()){
	GTEST_SKIP() << "No memfd support; skipping memfd-ashmem compat tests";
	}
	}
	};

	TEST_F(AshmemTestMemfdAshmemCompat, SetNameTest) {
	unique_fd fd;

	// ioctl() should fail, since memfd names cannot be changed after the buffer has been created.
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));
	ASSERT_LT(ioctl(fd, ASHMEM_SET_NAME, "invalid-command"), 0);
	}

	TEST_F(AshmemTestMemfdAshmemCompat, GetNameTest) {
	unique_fd fd;
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));

	char testBuf[ASHMEM_NAME_LEN];
	ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, &testBuf));
	// ashmem_create_region(nullptr, ...) creates memfds with the name "none".
	ASSERT_STREQ(testBuf, "none");
	}

	TEST_F(AshmemTestMemfdAshmemCompat, GetLongNameMemfdTests) {
	// memfd names have a maximum length of 249 bytes excluding the NUL terminating byte.
	// See: https://man7.org/linux/man-pages/man2/memfd_create.2.html
	const size_t max_memfd_name_len = 249;
	std::string longName(max_memfd_name_len, 'A');
	size_t pageSize = getpagesize();
	unique_fd fd;
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(pageSize, fd, PROT_READ \| PROT_WRITE \| PROT_EXEC,
	longName.c_str()));

	char retName[max_memfd_name_len + 1];
	ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_NAME, retName));
	ASSERT_STREQ(retName, longName.c_str());

	longName.append(1, 'A');
	// Use ashmem_create_region() since it should fail, since the string is now over the maximum
	// length.
	ASSERT_LT(ashmem_create_region(longName.c_str(), pageSize), 0);
	}

	TEST_F(AshmemTestMemfdAshmemCompat, SetSizeTest) {
	unique_fd fd;

	// ioctl() should fail, since libcutils sets and seals the buffer size after creating it.
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));
	ASSERT_LT(ioctl(fd, ASHMEM_SET_SIZE, 2 * getpagesize()), 0);
	}

	TEST_F(AshmemTestMemfdAshmemCompat, GetSizeTest) {
	unique_fd fd;
	size_t bufSize = getpagesize();

	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(bufSize, fd, PROT_READ \| PROT_WRITE \| PROT_EXEC));
	ASSERT_EQ(static_cast<int>(bufSize), ioctl(fd, ASHMEM_GET_SIZE, 0));
	}

	TEST_F(AshmemTestMemfdAshmemCompat, ProtMaskTest) {
	unique_fd fd;
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));

	// We can only change PROT_WRITE for memfds since memfd implements ashmem's prot_mask through
	// file seals, and only write seals exist.
	//
	// All memfd files start off as being writable (i.e. PROT_WRITE is part of the prot_mask).
	// Test to ensure that the implementation only clears the PROT_WRITE bit when requested.
	ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_PROT_MASK, PROT_READ \| PROT_WRITE \| PROT_EXEC));
	int prot = ioctl(fd, ASHMEM_GET_PROT_MASK, 0);
	ASSERT_NE(prot, -1);
	ASSERT_TRUE(prot & PROT_WRITE) << prot;

	ASSERT_EQ(0, ioctl(fd, ASHMEM_SET_PROT_MASK, PROT_READ \| PROT_EXEC));
	prot = ioctl(fd, ASHMEM_GET_PROT_MASK, 0);
	ASSERT_NE(prot, -1);
	ASSERT_TRUE(!(prot & PROT_WRITE)) << prot;

	// The shim layer should implement clearing PROT_WRITE via file seals, so check the file
	// seals to ensure that F_SEAL_FUTURE_WRITE is set.
	int seals = fcntl(fd, F_GET_SEALS, 0);
	ASSERT_NE(seals, -1);
	ASSERT_TRUE(seals & F_SEAL_FUTURE_WRITE) << seals;

	// Similarly, ensure that file seals affect prot_mask
	unique_fd fd2;
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd2, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));
	ASSERT_EQ(0, fcntl(fd2, F_ADD_SEALS, F_SEAL_FUTURE_WRITE));
	prot = ioctl(fd2, ASHMEM_GET_PROT_MASK, 0);
	ASSERT_NE(prot, -1);
	ASSERT_TRUE(!(prot & PROT_WRITE)) << prot;

	// And finally, ensure that adding back permissions fails
	ASSERT_LT(ioctl(fd2, ASHMEM_SET_PROT_MASK, PROT_READ \| PROT_WRITE \| PROT_EXEC), 0);
	}

	TEST_F(AshmemTestMemfdAshmemCompat, FileIDTest) {
	unique_fd fd;
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));

	unsigned long ino;
	ASSERT_EQ(0, ioctl(fd, ASHMEM_GET_FILE_ID, &ino));
	struct stat st;
	ASSERT_EQ(0, fstat(fd, &st));
	ASSERT_EQ(ino, st.st_ino);
	}

	TEST_F(AshmemTestMemfdAshmemCompat, UnpinningTest) {
	unique_fd fd;
	size_t bufSize = getpagesize();
	ASSERT_NO_FATAL_FAILURE(TestCreateRegion(getpagesize(), fd, PROT_READ \| PROT_WRITE \|
	PROT_EXEC));

	struct ashmem_pin pin = {
	.offset = 0,
	.len = static_cast<uint32_t>(bufSize),
	};
	ASSERT_EQ(0, ioctl(fd, ASHMEM_UNPIN, &pin));
	// ASHMEM_UNPIN should just be a nop
	ASSERT_EQ(ASHMEM_IS_PINNED, ioctl(fd, ASHMEM_GET_PIN_STATUS, 0));

	// This shouldn't do anything; when we pin the page, it shouldn't have been purged.
	ASSERT_EQ(0, ioctl(fd, ASHMEM_PURGE_ALL_CACHES, 0));
	ASSERT_EQ(ASHMEM_NOT_PURGED, ioctl(fd, ASHMEM_PIN, &pin));
	}