作者: 韩晨旭 10225101440 李畅 10225102463
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include <sys/resource.h>
#include <sys/wait.h>
#include <unistd.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <unordered_set>
#include <vector>
#include "gtest/gtest.h"
#include "leveldb/env.h"
#include "port/port.h"
#include "util/env_posix_test_helper.h"
#include "util/testutil.h"
#if HAVE_O_CLOEXEC
namespace {
// Exit codes for the helper process spawned by TestCloseOnExec* tests.
// Useful for debugging test failures.
constexpr int kTextCloseOnExecHelperExecFailedCode = 61;
constexpr int kTextCloseOnExecHelperDup2FailedCode = 62;
constexpr int kTextCloseOnExecHelperFoundOpenFdCode = 63;
// Global set by main() and read in TestCloseOnExec.
//
// The argv[0] value is stored in a std::vector instead of a std::string because
// std::string does not return a mutable pointer to its buffer until C++17.
//
// The vector stores the string pointed to by argv[0], plus the trailing null.
std::vector<char>* GetArgvZero() {
static std::vector<char> program_name;
return &program_name;
}
// Command-line switch used to run this test as the CloseOnExecSwitch helper.
static const char kTestCloseOnExecSwitch[] = "--test-close-on-exec-helper";
// Executed in a separate process by TestCloseOnExec* tests.
//
// main() delegates to this function when the test executable is launched with
// a special command-line switch. TestCloseOnExec* tests fork()+exec() the test
// executable and pass the special command-line switch.
//
// main() delegates to this function when the test executable is launched with
// a special command-line switch. TestCloseOnExec* tests fork()+exec() the test
// executable and pass the special command-line switch.
//
// When main() delegates to this function, the process probes whether a given
// file descriptor is open, and communicates the result via its exit code.
int TestCloseOnExecHelperMain(char* pid_arg) {
int fd = std::atoi(pid_arg);
// When given the same file descriptor twice, dup2() returns -1 if the
// file descriptor is closed, or the given file descriptor if it is open.
if (::dup2(fd, fd) == fd) {
std::fprintf(stderr, "Unexpected open fd %d\n", fd);
return kTextCloseOnExecHelperFoundOpenFdCode;
}
// Double-check that dup2() is saying the file descriptor is closed.
if (errno != EBADF) {
std::fprintf(stderr, "Unexpected errno after calling dup2 on fd %d: %s\n",
fd, std::strerror(errno));
return kTextCloseOnExecHelperDup2FailedCode;
}
return 0;
}
// File descriptors are small non-negative integers.
//
// Returns void so the implementation can use ASSERT_EQ.
void GetMaxFileDescriptor(int* result_fd) {
// Get the maximum file descriptor number.
::rlimit fd_rlimit;
ASSERT_EQ(0, ::getrlimit(RLIMIT_NOFILE, &fd_rlimit));
*result_fd = fd_rlimit.rlim_cur;
}
// Iterates through all possible FDs and returns the currently open ones.
//
// Returns void so the implementation can use ASSERT_EQ.
void GetOpenFileDescriptors(std::unordered_set<int>* open_fds) {
int max_fd = 0;
GetMaxFileDescriptor(&max_fd);
for (int fd = 0; fd < max_fd; ++fd) {
if (::dup2(fd, fd) != fd) {
// When given the same file descriptor twice, dup2() returns -1 if the
// file descriptor is closed, or the given file descriptor if it is open.
//
// Double-check that dup2() is saying the fd is closed.
ASSERT_EQ(EBADF, errno)
<< "dup2() should set errno to EBADF on closed file descriptors";
continue;
}
open_fds->insert(fd);
}
}
// Finds an FD open since a previous call to GetOpenFileDescriptors().
//
// |baseline_open_fds| is the result of a previous GetOpenFileDescriptors()
// call. Assumes that exactly one FD was opened since that call.
//
// Returns void so the implementation can use ASSERT_EQ.
void GetNewlyOpenedFileDescriptor(
const std::unordered_set<int>& baseline_open_fds, int* result_fd) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
for (int fd : baseline_open_fds) {
ASSERT_EQ(1, open_fds.count(fd))
<< "Previously opened file descriptor was closed during test setup";
open_fds.erase(fd);
}
ASSERT_EQ(1, open_fds.size())
<< "Expected exactly one newly opened file descriptor during test setup";
*result_fd = *open_fds.begin();
}
// Check that a fork()+exec()-ed child process does not have an extra open FD.
void CheckCloseOnExecDoesNotLeakFDs(
const std::unordered_set<int>& baseline_open_fds) {
// Prepare the argument list for the child process.
// execv() wants mutable buffers.
char switch_buffer[sizeof(kTestCloseOnExecSwitch)];
std::memcpy(switch_buffer, kTestCloseOnExecSwitch,
sizeof(kTestCloseOnExecSwitch));
int probed_fd;
GetNewlyOpenedFileDescriptor(baseline_open_fds, &probed_fd);
std::string fd_string = std::to_string(probed_fd);
std::vector<char> fd_buffer(fd_string.begin(), fd_string.end());
fd_buffer.emplace_back('\0');
// The helper process is launched with the command below.
// env_posix_tests --test-close-on-exec-helper 3
char* child_argv[] = {GetArgvZero()->data(), switch_buffer, fd_buffer.data(),
nullptr};
constexpr int kForkInChildProcessReturnValue = 0;
int child_pid = fork();
if (child_pid == kForkInChildProcessReturnValue) {
::execv(child_argv[0], child_argv);
std::fprintf(stderr, "Error spawning child process: %s\n", strerror(errno));
std::exit(kTextCloseOnExecHelperExecFailedCode);
}
int child_status = 0;
ASSERT_EQ(child_pid, ::waitpid(child_pid, &child_status, 0));
ASSERT_TRUE(WIFEXITED(child_status))
<< "The helper process did not exit with an exit code";
ASSERT_EQ(0, WEXITSTATUS(child_status))
<< "The helper process encountered an error";
}
} // namespace
#endif // HAVE_O_CLOEXEC
namespace leveldb {
static const int kReadOnlyFileLimit = 4;
static const int kMMapLimit = 4;
class EnvPosixTest : public testing::Test {
public:
static void SetFileLimits(int read_only_file_limit, int mmap_limit) {
EnvPosixTestHelper::SetReadOnlyFDLimit(read_only_file_limit);
EnvPosixTestHelper::SetReadOnlyMMapLimit(mmap_limit);
}
EnvPosixTest() : env_(Env::Default()) {}
Env* env_;
};
TEST_F(EnvPosixTest, TestOpenOnRead) {
// Write some test data to a single file that will be opened |n| times.
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string test_file = test_dir + "/open_on_read.txt";
FILE* f = std::fopen(test_file.c_str(), "we");
ASSERT_TRUE(f != nullptr);
const char kFileData[] = "abcdefghijklmnopqrstuvwxyz";
fputs(kFileData, f);
std::fclose(f);
// Open test file some number above the sum of the two limits to force
// open-on-read behavior of POSIX Env leveldb::RandomAccessFile.
const int kNumFiles = kReadOnlyFileLimit + kMMapLimit + 5;
leveldb::RandomAccessFile* files[kNumFiles] = {0};
for (int i = 0; i < kNumFiles; i++) {
ASSERT_LEVELDB_OK(env_->NewRandomAccessFile(test_file, &files[i]));
}
char scratch;
Slice read_result;
for (int i = 0; i < kNumFiles; i++) {
ASSERT_LEVELDB_OK(files[i]->Read(i, 1, &read_result, &scratch));
ASSERT_EQ(kFileData[i], read_result[0]);
}
for (int i = 0; i < kNumFiles; i++) {
delete files[i];
}
ASSERT_LEVELDB_OK(env_->RemoveFile(test_file));
}
#if HAVE_O_CLOEXEC
TEST_F(EnvPosixTest, TestCloseOnExecSequentialFile) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string file_path = test_dir + "/close_on_exec_sequential.txt";
ASSERT_LEVELDB_OK(WriteStringToFile(env_, "0123456789", file_path));
leveldb::SequentialFile* file = nullptr;
ASSERT_LEVELDB_OK(env_->NewSequentialFile(file_path, &file));
CheckCloseOnExecDoesNotLeakFDs(open_fds);
delete file;
ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
}
TEST_F(EnvPosixTest, TestCloseOnExecRandomAccessFile) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string file_path = test_dir + "/close_on_exec_random_access.txt";
ASSERT_LEVELDB_OK(WriteStringToFile(env_, "0123456789", file_path));
// Exhaust the RandomAccessFile mmap limit. This way, the test
// RandomAccessFile instance below is backed by a file descriptor, not by an
// mmap region.
leveldb::RandomAccessFile* mmapped_files[kMMapLimit];
for (int i = 0; i < kMMapLimit; i++) {
ASSERT_LEVELDB_OK(env_->NewRandomAccessFile(file_path, &mmapped_files[i]));
}
leveldb::RandomAccessFile* file = nullptr;
ASSERT_LEVELDB_OK(env_->NewRandomAccessFile(file_path, &file));
CheckCloseOnExecDoesNotLeakFDs(open_fds);
delete file;
for (int i = 0; i < kMMapLimit; i++) {
delete mmapped_files[i];
}
ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
}
TEST_F(EnvPosixTest, TestCloseOnExecWritableFile) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string file_path = test_dir + "/close_on_exec_writable.txt";
ASSERT_LEVELDB_OK(WriteStringToFile(env_, "0123456789", file_path));
leveldb::WritableFile* file = nullptr;
ASSERT_LEVELDB_OK(env_->NewWritableFile(file_path, &file));
CheckCloseOnExecDoesNotLeakFDs(open_fds);
delete file;
ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
}
TEST_F(EnvPosixTest, TestCloseOnExecAppendableFile) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string file_path = test_dir + "/close_on_exec_appendable.txt";
ASSERT_LEVELDB_OK(WriteStringToFile(env_, "0123456789", file_path));
leveldb::WritableFile* file = nullptr;
ASSERT_LEVELDB_OK(env_->NewAppendableFile(file_path, &file));
CheckCloseOnExecDoesNotLeakFDs(open_fds);
delete file;
ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
}
TEST_F(EnvPosixTest, TestCloseOnExecLockFile) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string file_path = test_dir + "/close_on_exec_lock.txt";
ASSERT_LEVELDB_OK(WriteStringToFile(env_, "0123456789", file_path));
leveldb::FileLock* lock = nullptr;
ASSERT_LEVELDB_OK(env_->LockFile(file_path, &lock));
CheckCloseOnExecDoesNotLeakFDs(open_fds);
ASSERT_LEVELDB_OK(env_->UnlockFile(lock));
ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
}
TEST_F(EnvPosixTest, TestCloseOnExecLogger) {
std::unordered_set<int> open_fds;
GetOpenFileDescriptors(&open_fds);
std::string test_dir;
ASSERT_LEVELDB_OK(env_->GetTestDirectory(&test_dir));
std::string file_path = test_dir + "/close_on_exec_logger.txt";
ASSERT_LEVELDB_OK(WriteStringToFile(env_, "0123456789", file_path));
leveldb::Logger* file = nullptr;
ASSERT_LEVELDB_OK(env_->NewLogger(file_path, &file));
CheckCloseOnExecDoesNotLeakFDs(open_fds);
delete file;
ASSERT_LEVELDB_OK(env_->RemoveFile(file_path));
}
#endif // HAVE_O_CLOEXEC
} // namespace leveldb
int main(int argc, char** argv) {
#if HAVE_O_CLOEXEC
// Check if we're invoked as a helper program, or as the test suite.
for (int i = 1; i < argc; ++i) {
if (!std::strcmp(argv[i], kTestCloseOnExecSwitch)) {
return TestCloseOnExecHelperMain(argv[i + 1]);
}
}
// Save argv[0] early, because googletest may modify argv.
GetArgvZero()->assign(argv[0], argv[0] + std::strlen(argv[0]) + 1);
#endif // HAVE_O_CLOEXEC
// All tests currently run with the same read-only file limits.
leveldb::EnvPosixTest::SetFileLimits(leveldb::kReadOnlyFileLimit,
leveldb::kMMapLimit);
testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}