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Diffstat (limited to 'test/syscalls/linux/wait.cc')
| -rw-r--r-- | test/syscalls/linux/wait.cc | 913 |
1 files changed, 913 insertions, 0 deletions
diff --git a/test/syscalls/linux/wait.cc b/test/syscalls/linux/wait.cc new file mode 100644 index 000000000..944149d5e --- /dev/null +++ b/test/syscalls/linux/wait.cc @@ -0,0 +1,913 @@ +// Copyright 2018 The gVisor Authors. +// +// 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 <signal.h> +#include <sys/mman.h> +#include <sys/ptrace.h> +#include <sys/resource.h> +#include <sys/time.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <unistd.h> + +#include <functional> +#include <tuple> +#include <vector> + +#include "gmock/gmock.h" +#include "gtest/gtest.h" +#include "absl/strings/str_cat.h" +#include "absl/synchronization/mutex.h" +#include "absl/time/clock.h" +#include "absl/time/time.h" +#include "test/util/cleanup.h" +#include "test/util/file_descriptor.h" +#include "test/util/logging.h" +#include "test/util/multiprocess_util.h" +#include "test/util/posix_error.h" +#include "test/util/signal_util.h" +#include "test/util/test_util.h" +#include "test/util/thread_util.h" +#include "test/util/time_util.h" + +using ::testing::UnorderedElementsAre; + +// These unit tests focus on the wait4(2) system call, but include a basic +// checks for the i386 waitpid(2) syscall, which is a subset of wait4(2). +// +// NOTE(b/22640830,b/27680907,b/29049891): Some functionality is not tested as +// it is not currently supported by gVisor: +// * Process groups. +// * Core dump status (WCOREDUMP). +// +// Tests for waiting on stopped/continued children are in sigstop.cc. + +namespace gvisor { +namespace testing { + +namespace { + +// The CloneChild function seems to need more than one page of stack space. +static const size_t kStackSize = 2 * kPageSize; + +// The child thread created in CloneAndExit runs this function. +// This child does not have the TLS setup, so it must not use glibc functions. +int CloneChild(void* priv) { + int64_t sleep = reinterpret_cast<int64_t>(priv); + SleepSafe(absl::Seconds(sleep)); + + // glibc's _exit(2) function wrapper will helpfully call exit_group(2), + // exiting the entire process. + syscall(__NR_exit, 0); + return 1; +} + +// ForkAndExit forks a child process which exits with exit_code, after +// sleeping for the specified duration (seconds). +pid_t ForkAndExit(int exit_code, int64_t sleep) { + pid_t child = fork(); + if (child == 0) { + SleepSafe(absl::Seconds(sleep)); + _exit(exit_code); + } + return child; +} + +int64_t clock_gettime_nsecs(clockid_t id) { + struct timespec ts; + TEST_PCHECK(clock_gettime(id, &ts) == 0); + return (ts.tv_sec * 1000000000 + ts.tv_nsec); +} + +void spin(int64_t sec) { + int64_t ns = sec * 1000000000; + int64_t start = clock_gettime_nsecs(CLOCK_THREAD_CPUTIME_ID); + int64_t end = start + ns; + + do { + constexpr int kLoopCount = 1000000; // large and arbitrary + // volatile to prevent the compiler from skipping this loop. + for (volatile int i = 0; i < kLoopCount; i++) { + } + } while (clock_gettime_nsecs(CLOCK_THREAD_CPUTIME_ID) < end); +} + +// ForkSpinAndExit forks a child process which exits with exit_code, after +// spinning for the specified duration (seconds). +pid_t ForkSpinAndExit(int exit_code, int64_t spintime) { + pid_t child = fork(); + if (child == 0) { + spin(spintime); + _exit(exit_code); + } + return child; +} + +absl::Duration RusageCpuTime(const struct rusage& ru) { + return absl::DurationFromTimeval(ru.ru_utime) + + absl::DurationFromTimeval(ru.ru_stime); +} + +// Returns the address of the top of the stack. +// Free with FreeStack. +uintptr_t AllocStack() { + void* addr = mmap(nullptr, kStackSize, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + + if (addr == MAP_FAILED) { + return reinterpret_cast<uintptr_t>(MAP_FAILED); + } + + return reinterpret_cast<uintptr_t>(addr) + kStackSize; +} + +// Frees a stack page allocated with AllocStack. +int FreeStack(uintptr_t addr) { + addr -= kStackSize; + return munmap(reinterpret_cast<void*>(addr), kPageSize); +} + +// CloneAndExit clones a child thread, which exits with 0 after sleeping for +// the specified duration (must be in seconds). extra_flags are ORed against +// the standard clone(2) flags. +int CloneAndExit(int64_t sleep, uintptr_t stack, int extra_flags) { + return clone(CloneChild, reinterpret_cast<void*>(stack), + CLONE_FILES | CLONE_FS | CLONE_SIGHAND | CLONE_VM | extra_flags, + reinterpret_cast<void*>(sleep)); +} + +// Simple wrappers around wait4(2) and waitid(2) that ignore interrupts. +constexpr auto Wait4 = RetryEINTR(wait4); +constexpr auto Waitid = RetryEINTR(waitid); + +// Fixture for tests parameterized by a function that waits for any child to +// exit with the given options, checks that it exited with the given code, and +// then returns its PID. +// +// N.B. These tests run in a multi-threaded environment. We assume that +// background threads do not create child processes and are not themselves +// created with clone(... | SIGCHLD). Either may cause these tests to +// erroneously wait on child processes/threads. +class WaitAnyChildTest : public ::testing::TestWithParam< + std::function<PosixErrorOr<pid_t>(int, int)>> { + protected: + PosixErrorOr<pid_t> WaitAny(int code) { return WaitAnyWithOptions(code, 0); } + + PosixErrorOr<pid_t> WaitAnyWithOptions(int code, int options) { + return GetParam()(code, options); + } +}; + +// Wait for any child to exit. +TEST_P(WaitAnyChildTest, Fork) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + + EXPECT_THAT(WaitAny(0), IsPosixErrorOkAndHolds(child)); +} + +// Call wait4 for any process after the child has already exited. +TEST_P(WaitAnyChildTest, AfterExit) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + + absl::SleepFor(absl::Seconds(5)); + + EXPECT_THAT(WaitAny(0), IsPosixErrorOkAndHolds(child)); +} + +// Wait for multiple children to exit, waiting for either at a time. +TEST_P(WaitAnyChildTest, MultipleFork) { + pid_t child1, child2; + ASSERT_THAT(child1 = ForkAndExit(0, 0), SyscallSucceeds()); + ASSERT_THAT(child2 = ForkAndExit(0, 0), SyscallSucceeds()); + + std::vector<pid_t> pids; + pids.push_back(ASSERT_NO_ERRNO_AND_VALUE(WaitAny(0))); + pids.push_back(ASSERT_NO_ERRNO_AND_VALUE(WaitAny(0))); + EXPECT_THAT(pids, UnorderedElementsAre(child1, child2)); +} + +// Wait for any child to exit. +// A non-CLONE_THREAD child which sends SIGCHLD upon exit behaves much like +// a forked process. +TEST_P(WaitAnyChildTest, CloneSIGCHLD) { + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int child; + ASSERT_THAT(child = CloneAndExit(0, stack, SIGCHLD), SyscallSucceeds()); + + EXPECT_THAT(WaitAny(0), IsPosixErrorOkAndHolds(child)); +} + +// Wait for a child thread and process. +TEST_P(WaitAnyChildTest, ForkAndClone) { + pid_t process; + ASSERT_THAT(process = ForkAndExit(0, 0), SyscallSucceeds()); + + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int thread; + // Send SIGCHLD for normal wait semantics. + ASSERT_THAT(thread = CloneAndExit(0, stack, SIGCHLD), SyscallSucceeds()); + + std::vector<pid_t> pids; + pids.push_back(ASSERT_NO_ERRNO_AND_VALUE(WaitAny(0))); + pids.push_back(ASSERT_NO_ERRNO_AND_VALUE(WaitAny(0))); + EXPECT_THAT(pids, UnorderedElementsAre(process, thread)); +} + +// Return immediately if no child has exited. +TEST_P(WaitAnyChildTest, WaitWNOHANG) { + EXPECT_THAT(WaitAnyWithOptions(0, WNOHANG), + PosixErrorIs(ECHILD, ::testing::_)); +} + +// Bad options passed +TEST_P(WaitAnyChildTest, BadOption) { + EXPECT_THAT(WaitAnyWithOptions(0, 123456), + PosixErrorIs(EINVAL, ::testing::_)); +} + +TEST_P(WaitAnyChildTest, WaitedChildRusage) { + struct rusage before; + ASSERT_THAT(getrusage(RUSAGE_CHILDREN, &before), SyscallSucceeds()); + + pid_t child; + constexpr absl::Duration kSpin = absl::Seconds(3); + ASSERT_THAT(child = ForkSpinAndExit(0, absl::ToInt64Seconds(kSpin)), + SyscallSucceeds()); + ASSERT_THAT(WaitAny(0), IsPosixErrorOkAndHolds(child)); + + struct rusage after; + ASSERT_THAT(getrusage(RUSAGE_CHILDREN, &after), SyscallSucceeds()); + + EXPECT_GE(RusageCpuTime(after) - RusageCpuTime(before), kSpin); +} + +TEST_P(WaitAnyChildTest, IgnoredChildRusage) { + // "POSIX.1-2001 specifies that if the disposition of SIGCHLD is + // set to SIG_IGN or the SA_NOCLDWAIT flag is set for SIGCHLD (see + // sigaction(2)), then children that terminate do not become zombies and a + // call to wait() or waitpid() will block until all children have terminated, + // and then fail with errno set to ECHILD." - waitpid(2) + // + // "RUSAGE_CHILDREN: Return resource usage statistics for all children of the + // calling process that have terminated *and been waited for*." - + // getrusage(2), emphasis added + + struct sigaction sa; + sa.sa_handler = SIG_IGN; + const auto cleanup_sigact = + ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGCHLD, sa)); + + struct rusage before; + ASSERT_THAT(getrusage(RUSAGE_CHILDREN, &before), SyscallSucceeds()); + + const absl::Duration start = + absl::Nanoseconds(clock_gettime_nsecs(CLOCK_MONOTONIC)); + + constexpr absl::Duration kSpin = absl::Seconds(3); + + // ForkAndSpin uses CLOCK_THREAD_CPUTIME_ID, which is lower resolution than, + // and may diverge from, CLOCK_MONOTONIC, so we allow a small grace period but + // still check that we blocked for a while. + constexpr absl::Duration kSpinGrace = absl::Milliseconds(100); + + pid_t child; + ASSERT_THAT(child = ForkSpinAndExit(0, absl::ToInt64Seconds(kSpin)), + SyscallSucceeds()); + ASSERT_THAT(WaitAny(0), PosixErrorIs(ECHILD, ::testing::_)); + const absl::Duration end = + absl::Nanoseconds(clock_gettime_nsecs(CLOCK_MONOTONIC)); + EXPECT_GE(end - start, kSpin - kSpinGrace); + + struct rusage after; + ASSERT_THAT(getrusage(RUSAGE_CHILDREN, &after), SyscallSucceeds()); + EXPECT_EQ(before.ru_utime.tv_sec, after.ru_utime.tv_sec); + EXPECT_EQ(before.ru_utime.tv_usec, after.ru_utime.tv_usec); + EXPECT_EQ(before.ru_stime.tv_sec, after.ru_stime.tv_sec); + EXPECT_EQ(before.ru_stime.tv_usec, after.ru_stime.tv_usec); +} + +INSTANTIATE_TEST_SUITE_P( + Waiters, WaitAnyChildTest, + ::testing::Values( + [](int code, int options) -> PosixErrorOr<pid_t> { + int status; + auto const pid = Wait4(-1, &status, options, nullptr); + MaybeSave(); + if (pid < 0) { + return PosixError(errno, "wait4"); + } + if (!WIFEXITED(status) || WEXITSTATUS(status) != code) { + return PosixError( + EINVAL, absl::StrCat("unexpected wait status: got ", status, + ", wanted ", code)); + } + return static_cast<pid_t>(pid); + }, + [](int code, int options) -> PosixErrorOr<pid_t> { + siginfo_t si; + auto const rv = Waitid(P_ALL, 0, &si, WEXITED | options); + MaybeSave(); + if (rv < 0) { + return PosixError(errno, "waitid"); + } + if (si.si_signo != SIGCHLD) { + return PosixError( + EINVAL, absl::StrCat("unexpected signo: got ", si.si_signo, + ", wanted ", SIGCHLD)); + } + if (si.si_status != code) { + return PosixError( + EINVAL, absl::StrCat("unexpected status: got ", si.si_status, + ", wanted ", code)); + } + if (si.si_code != CLD_EXITED) { + return PosixError(EINVAL, + absl::StrCat("unexpected code: got ", si.si_code, + ", wanted ", CLD_EXITED)); + } + auto const uid = getuid(); + if (si.si_uid != uid) { + return PosixError(EINVAL, + absl::StrCat("unexpected uid: got ", si.si_uid, + ", wanted ", uid)); + } + return static_cast<pid_t>(si.si_pid); + })); + +// Fixture for tests parameterized by a (sysno, function) tuple. The function +// takes the PID of a specific child to wait for, waits for it to exit, and +// checks that it exits with the given code. +class WaitSpecificChildTest + : public ::testing::TestWithParam< + std::tuple<int, std::function<PosixError(pid_t, int, int)>>> { + protected: + int Sysno() { return std::get<0>(GetParam()); } + + PosixError WaitForWithOptions(pid_t pid, int options, int code) { + return std::get<1>(GetParam())(pid, options, code); + } + + PosixError WaitFor(pid_t pid, int code) { + return std::get<1>(GetParam())(pid, 0, code); + } +}; + +// Wait for specific child to exit. +TEST_P(WaitSpecificChildTest, Fork) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +// Non-zero exit codes are correctly propagated. +TEST_P(WaitSpecificChildTest, NormalExit) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(42, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child, 42)); +} + +// Wait for multiple children to exit. +TEST_P(WaitSpecificChildTest, MultipleFork) { + pid_t child1, child2; + ASSERT_THAT(child1 = ForkAndExit(0, 0), SyscallSucceeds()); + ASSERT_THAT(child2 = ForkAndExit(0, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child1, 0)); + EXPECT_NO_ERRNO(WaitFor(child2, 0)); +} + +// Wait for multiple children to exit, out of the order they were created. +TEST_P(WaitSpecificChildTest, MultipleForkOutOfOrder) { + pid_t child1, child2; + ASSERT_THAT(child1 = ForkAndExit(0, 0), SyscallSucceeds()); + ASSERT_THAT(child2 = ForkAndExit(0, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child2, 0)); + EXPECT_NO_ERRNO(WaitFor(child1, 0)); +} + +// Wait for specific child to exit, entering wait4 before the exit occurs. +TEST_P(WaitSpecificChildTest, ForkSleep) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 5), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +// Wait should block until the child exits. +TEST_P(WaitSpecificChildTest, ForkBlock) { + pid_t child; + + auto start = absl::Now(); + ASSERT_THAT(child = ForkAndExit(0, 5), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); + + EXPECT_GE(absl::Now() - start, absl::Seconds(5)); +} + +// Waiting after the child has already exited returns immediately. +TEST_P(WaitSpecificChildTest, AfterExit) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + + absl::SleepFor(absl::Seconds(5)); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +// Wait for child of sibling thread. +TEST_P(WaitSpecificChildTest, SiblingChildren) { + absl::Mutex mu; + pid_t child; + bool ready = false; + bool stop = false; + + ScopedThread t([&] { + absl::MutexLock ml(&mu); + EXPECT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + ready = true; + mu.Await(absl::Condition(&stop)); + }); + + // N.B. This must be declared after ScopedThread, so it is destructed first, + // thus waking the thread. + absl::MutexLock ml(&mu); + mu.Await(absl::Condition(&ready)); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); + + // Keep the sibling alive until after we've waited so the child isn't + // reparented. + stop = true; +} + +// Waiting for child of sibling thread not allowed with WNOTHREAD. +TEST_P(WaitSpecificChildTest, SiblingChildrenWNOTHREAD) { + // Linux added WNOTHREAD support to waitid(2) in + // 91c4e8ea8f05916df0c8a6f383508ac7c9e10dba ("wait: allow sys_waitid() to + // accept __WNOTHREAD/__WCLONE/__WALL"). i.e., Linux 4.7. + // + // Skip the test if it isn't supported yet. + if (Sysno() == SYS_waitid) { + int ret = waitid(P_ALL, 0, nullptr, WEXITED | WNOHANG | __WNOTHREAD); + SKIP_IF(ret < 0 && errno == EINVAL); + } + + absl::Mutex mu; + pid_t child; + bool ready = false; + bool stop = false; + + ScopedThread t([&] { + absl::MutexLock ml(&mu); + EXPECT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + ready = true; + mu.Await(absl::Condition(&stop)); + + // This thread can wait on child. + EXPECT_NO_ERRNO(WaitForWithOptions(child, __WNOTHREAD, 0)); + }); + + // N.B. This must be declared after ScopedThread, so it is destructed first, + // thus waking the thread. + absl::MutexLock ml(&mu); + mu.Await(absl::Condition(&ready)); + + // This thread can't wait on child. + EXPECT_THAT(WaitForWithOptions(child, __WNOTHREAD, 0), + PosixErrorIs(ECHILD, ::testing::_)); + + // Keep the sibling alive until after we've waited so the child isn't + // reparented. + stop = true; +} + +// Wait for specific child to exit. +// A non-CLONE_THREAD child which sends SIGCHLD upon exit behaves much like +// a forked process. +TEST_P(WaitSpecificChildTest, CloneSIGCHLD) { + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int child; + ASSERT_THAT(child = CloneAndExit(0, stack, SIGCHLD), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +// Wait for specific child to exit. +// A non-CLONE_THREAD child which does not send SIGCHLD upon exit can be waited +// on, but returns ECHILD. +TEST_P(WaitSpecificChildTest, CloneNoSIGCHLD) { + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int child; + ASSERT_THAT(child = CloneAndExit(0, stack, 0), SyscallSucceeds()); + + EXPECT_THAT(WaitFor(child, 0), PosixErrorIs(ECHILD, ::testing::_)); +} + +// Waiting after the child has already exited returns immediately. +TEST_P(WaitSpecificChildTest, CloneAfterExit) { + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int child; + // Send SIGCHLD for normal wait semantics. + ASSERT_THAT(child = CloneAndExit(0, stack, SIGCHLD), SyscallSucceeds()); + + absl::SleepFor(absl::Seconds(5)); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +// A CLONE_THREAD child cannot be waited on. +TEST_P(WaitSpecificChildTest, CloneThread) { + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int child; + ASSERT_THAT(child = CloneAndExit(15, stack, CLONE_THREAD), SyscallSucceeds()); + auto start = absl::Now(); + + EXPECT_THAT(WaitFor(child, 0), PosixErrorIs(ECHILD, ::testing::_)); + + // Ensure wait4 didn't block. + EXPECT_LE(absl::Now() - start, absl::Seconds(10)); + + // Since we can't wait on the child, we sleep to try to avoid freeing its + // stack before it exits. + absl::SleepFor(absl::Seconds(5)); +} + +// A child that does not send a SIGCHLD on exit may be waited on with +// the __WCLONE flag. +TEST_P(WaitSpecificChildTest, CloneWCLONE) { + // Linux added WCLONE support to waitid(2) in + // 91c4e8ea8f05916df0c8a6f383508ac7c9e10dba ("wait: allow sys_waitid() to + // accept __WNOTHREAD/__WCLONE/__WALL"). i.e., Linux 4.7. + // + // Skip the test if it isn't supported yet. + if (Sysno() == SYS_waitid) { + int ret = waitid(P_ALL, 0, nullptr, WEXITED | WNOHANG | __WCLONE); + SKIP_IF(ret < 0 && errno == EINVAL); + } + + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + int child; + ASSERT_THAT(child = CloneAndExit(0, stack, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitForWithOptions(child, __WCLONE, 0)); +} + +// A forked child cannot be waited on with WCLONE. +TEST_P(WaitSpecificChildTest, ForkWCLONE) { + // Linux added WCLONE support to waitid(2) in + // 91c4e8ea8f05916df0c8a6f383508ac7c9e10dba ("wait: allow sys_waitid() to + // accept __WNOTHREAD/__WCLONE/__WALL"). i.e., Linux 4.7. + // + // Skip the test if it isn't supported yet. + if (Sysno() == SYS_waitid) { + int ret = waitid(P_ALL, 0, nullptr, WEXITED | WNOHANG | __WCLONE); + SKIP_IF(ret < 0 && errno == EINVAL); + } + + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + + EXPECT_THAT(WaitForWithOptions(child, WNOHANG | __WCLONE, 0), + PosixErrorIs(ECHILD, ::testing::_)); + + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +// Any type of child can be waited on with WALL. +TEST_P(WaitSpecificChildTest, WALL) { + // Linux added WALL support to waitid(2) in + // 91c4e8ea8f05916df0c8a6f383508ac7c9e10dba ("wait: allow sys_waitid() to + // accept __WNOTHREAD/__WCLONE/__WALL"). i.e., Linux 4.7. + // + // Skip the test if it isn't supported yet. + if (Sysno() == SYS_waitid) { + int ret = waitid(P_ALL, 0, nullptr, WEXITED | WNOHANG | __WALL); + SKIP_IF(ret < 0 && errno == EINVAL); + } + + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitForWithOptions(child, __WALL, 0)); + + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + ASSERT_THAT(child = CloneAndExit(0, stack, 0), SyscallSucceeds()); + + EXPECT_NO_ERRNO(WaitForWithOptions(child, __WALL, 0)); +} + +// Return ECHILD for bad child. +TEST_P(WaitSpecificChildTest, BadChild) { + EXPECT_THAT(WaitFor(42, 0), PosixErrorIs(ECHILD, ::testing::_)); +} + +// Wait for a child process that only exits after calling execve(2) from a +// non-leader thread. +TEST_P(WaitSpecificChildTest, AfterChildExecve) { + ExecveArray const owned_child_argv = {"/bin/true"}; + char* const* const child_argv = owned_child_argv.get(); + + uintptr_t stack; + ASSERT_THAT(stack = AllocStack(), SyscallSucceeds()); + auto free = + Cleanup([stack] { ASSERT_THAT(FreeStack(stack), SyscallSucceeds()); }); + + pid_t const child = fork(); + if (child == 0) { + // Give the parent some time to start waiting. + SleepSafe(absl::Seconds(5)); + // Pass CLONE_VFORK to block the original thread in the child process until + // the clone thread calls execve, annihilating them both. (This means that + // if clone returns at all, something went wrong.) + // + // N.B. clone(2) is not officially async-signal-safe, but at minimum glibc's + // x86_64 implementation is safe. See glibc + // sysdeps/unix/sysv/linux/x86_64/clone.S. + clone( + +[](void* arg) { + auto child_argv = static_cast<char* const*>(arg); + execve(child_argv[0], child_argv, /* envp = */ nullptr); + return errno; + }, + reinterpret_cast<void*>(stack), + CLONE_FILES | CLONE_FS | CLONE_SIGHAND | CLONE_THREAD | CLONE_VM | + CLONE_VFORK, + const_cast<char**>(child_argv)); + _exit(errno); + } + ASSERT_THAT(child, SyscallSucceeds()); + EXPECT_NO_ERRNO(WaitFor(child, 0)); +} + +PosixError CheckWait4(pid_t pid, int options, int code) { + int status; + auto const rv = Wait4(pid, &status, options, nullptr); + MaybeSave(); + if (rv < 0) { + return PosixError(errno, "wait4"); + } else if (rv != pid) { + return PosixError( + EINVAL, absl::StrCat("unexpected pid: got ", rv, ", wanted ", pid)); + } + if (!WIFEXITED(status) || WEXITSTATUS(status) != code) { + return PosixError(EINVAL, absl::StrCat("unexpected wait status: got ", + status, ", wanted ", code)); + } + return NoError(); +}; + +PosixError CheckWaitid(pid_t pid, int options, int code) { + siginfo_t si; + auto const rv = Waitid(P_PID, pid, &si, options | WEXITED); + MaybeSave(); + if (rv < 0) { + return PosixError(errno, "waitid"); + } + if (si.si_pid != pid) { + return PosixError(EINVAL, absl::StrCat("unexpected pid: got ", si.si_pid, + ", wanted ", pid)); + } + if (si.si_signo != SIGCHLD) { + return PosixError(EINVAL, absl::StrCat("unexpected signo: got ", + si.si_signo, ", wanted ", SIGCHLD)); + } + if (si.si_status != code) { + return PosixError(EINVAL, absl::StrCat("unexpected status: got ", + si.si_status, ", wanted ", code)); + } + if (si.si_code != CLD_EXITED) { + return PosixError(EINVAL, absl::StrCat("unexpected code: got ", si.si_code, + ", wanted ", CLD_EXITED)); + } + return NoError(); +} + +INSTANTIATE_TEST_SUITE_P( + Waiters, WaitSpecificChildTest, + ::testing::Values(std::make_tuple(SYS_wait4, CheckWait4), + std::make_tuple(SYS_waitid, CheckWaitid))); + +// WIFEXITED, WIFSIGNALED, WTERMSIG indicate signal exit. +TEST(WaitTest, SignalExit) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 10), SyscallSucceeds()); + + EXPECT_THAT(kill(child, SIGKILL), SyscallSucceeds()); + + int status; + EXPECT_THAT(Wait4(child, &status, 0, nullptr), + SyscallSucceedsWithValue(child)); + + EXPECT_FALSE(WIFEXITED(status)); + EXPECT_TRUE(WIFSIGNALED(status)); + EXPECT_EQ(SIGKILL, WTERMSIG(status)); +} + +// waitid requires at least one option. +TEST(WaitTest, WaitidOptions) { + EXPECT_THAT(Waitid(P_ALL, 0, nullptr, 0), SyscallFailsWithErrno(EINVAL)); +} + +// waitid does not wait for a child to exit if not passed WEXITED. +TEST(WaitTest, WaitidNoWEXITED) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(0, 0), SyscallSucceeds()); + EXPECT_THAT(Waitid(P_ALL, 0, nullptr, WSTOPPED), + SyscallFailsWithErrno(ECHILD)); + EXPECT_THAT(Waitid(P_ALL, 0, nullptr, WEXITED), SyscallSucceeds()); +} + +// WNOWAIT allows the same wait result to be returned again. +TEST(WaitTest, WaitidWNOWAIT) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(42, 0), SyscallSucceeds()); + + siginfo_t info; + ASSERT_THAT(Waitid(P_PID, child, &info, WEXITED | WNOWAIT), + SyscallSucceeds()); + EXPECT_EQ(child, info.si_pid); + EXPECT_EQ(SIGCHLD, info.si_signo); + EXPECT_EQ(CLD_EXITED, info.si_code); + EXPECT_EQ(42, info.si_status); + + ASSERT_THAT(Waitid(P_PID, child, &info, WEXITED), SyscallSucceeds()); + EXPECT_EQ(child, info.si_pid); + EXPECT_EQ(SIGCHLD, info.si_signo); + EXPECT_EQ(CLD_EXITED, info.si_code); + EXPECT_EQ(42, info.si_status); + + EXPECT_THAT(Waitid(P_PID, child, &info, WEXITED), + SyscallFailsWithErrno(ECHILD)); +} + +// waitpid(pid, status, options) is equivalent to +// wait4(pid, status, options, nullptr). +// This is a dedicated syscall on i386, glibc maps it to wait4 on amd64. +TEST(WaitTest, WaitPid) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(42, 0), SyscallSucceeds()); + + int status; + EXPECT_THAT(RetryEINTR(waitpid)(child, &status, 0), + SyscallSucceedsWithValue(child)); + + EXPECT_TRUE(WIFEXITED(status)); + EXPECT_EQ(42, WEXITSTATUS(status)); +} + +// Test that signaling a zombie succeeds. This is a signals test that is in this +// file for some reason. +TEST(WaitTest, KillZombie) { + pid_t child; + ASSERT_THAT(child = ForkAndExit(42, 0), SyscallSucceeds()); + + // Sleep for three seconds to ensure the child has exited. + absl::SleepFor(absl::Seconds(3)); + + // The child is now a zombie. Check that killing it returns 0. + EXPECT_THAT(kill(child, SIGTERM), SyscallSucceeds()); + EXPECT_THAT(kill(child, 0), SyscallSucceeds()); + + EXPECT_THAT(Wait4(child, nullptr, 0, nullptr), + SyscallSucceedsWithValue(child)); +} + +TEST(WaitTest, Wait4Rusage) { + pid_t child; + constexpr absl::Duration kSpin = absl::Seconds(3); + ASSERT_THAT(child = ForkSpinAndExit(21, absl::ToInt64Seconds(kSpin)), + SyscallSucceeds()); + + int status; + struct rusage rusage = {}; + ASSERT_THAT(Wait4(child, &status, 0, &rusage), + SyscallSucceedsWithValue(child)); + + EXPECT_TRUE(WIFEXITED(status)); + EXPECT_EQ(21, WEXITSTATUS(status)); + + EXPECT_GE(RusageCpuTime(rusage), kSpin); +} + +TEST(WaitTest, WaitidRusage) { + pid_t child; + constexpr absl::Duration kSpin = absl::Seconds(3); + ASSERT_THAT(child = ForkSpinAndExit(27, absl::ToInt64Seconds(kSpin)), + SyscallSucceeds()); + + siginfo_t si = {}; + struct rusage rusage = {}; + + // From waitid(2): + // The raw waitid() system call takes a fifth argument, of type + // struct rusage *. If this argument is non-NULL, then it is used + // to return resource usage information about the child, in the + // same manner as wait4(2). + EXPECT_THAT( + RetryEINTR(syscall)(SYS_waitid, P_PID, child, &si, WEXITED, &rusage), + SyscallSucceeds()); + EXPECT_EQ(si.si_signo, SIGCHLD); + EXPECT_EQ(si.si_code, CLD_EXITED); + EXPECT_EQ(si.si_status, 27); + EXPECT_EQ(si.si_pid, child); + + EXPECT_GE(RusageCpuTime(rusage), kSpin); +} + +// After bf959931ddb88c4e4366e96dd22e68fa0db9527c ("wait/ptrace: assume __WALL +// if the child is traced") (Linux 4.7), tracees are always eligible for +// waiting, regardless of type. +TEST(WaitTest, TraceeWALL) { + int fds[2]; + ASSERT_THAT(pipe(fds), SyscallSucceeds()); + FileDescriptor rfd(fds[0]); + FileDescriptor wfd(fds[1]); + + pid_t child = fork(); + if (child == 0) { + // Child. + rfd.reset(); + + TEST_PCHECK(ptrace(PTRACE_TRACEME, 0, nullptr, nullptr) == 0); + + // Notify parent that we're now a tracee. + wfd.reset(); + + _exit(0); + } + ASSERT_THAT(child, SyscallSucceeds()); + + wfd.reset(); + + // Wait for child to become tracee. + char c; + EXPECT_THAT(ReadFd(rfd.get(), &c, sizeof(c)), SyscallSucceedsWithValue(0)); + + // We can wait on the fork child with WCLONE, as it is a tracee. + int status; + if (IsRunningOnGvisor()) { + ASSERT_THAT(Wait4(child, &status, __WCLONE, nullptr), + SyscallSucceedsWithValue(child)); + + EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status; + } else { + // On older versions of Linux, we may get ECHILD. + ASSERT_THAT(Wait4(child, &status, __WCLONE, nullptr), + ::testing::AnyOf(SyscallSucceedsWithValue(child), + SyscallFailsWithErrno(ECHILD))); + } +} + +} // namespace + +} // namespace testing +} // namespace gvisor |