moved process handling code into separate h/cpp (#555)

1 files changed, 708 insertions, 0 deletions

diff --git a/src/zencore/process.cpp b/src/zencore/process.cpp
new file mode 100644
index 000000000..1c208701c
--- /dev/null
+++ b/src/zencore/process.cpp
@@ -0,0 +1,708 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zencore/process.h>
+
+#include <zencore/except.h>
+#include <zencore/filesystem.h>
+#include <zencore/fmtutils.h>
+#include <zencore/scopeguard.h>
+#include <zencore/string.h>
+#include <zencore/testing.h>
+
+#include <thread>
+
+#if ZEN_PLATFORM_WINDOWS
+#	include <shellapi.h>
+#	include <Shlobj.h>
+#	include <zencore/windows.h>
+#else
+#	include <fcntl.h>
+#	include <pthread.h>
+#	include <signal.h>
+#	include <sys/file.h>
+#	include <sys/sem.h>
+#	include <sys/stat.h>
+#	include <sys/syscall.h>
+#	include <sys/wait.h>
+#	include <time.h>
+#	include <unistd.h>
+#endif
+
+ZEN_THIRD_PARTY_INCLUDES_START
+#include <fmt/format.h>
+ZEN_THIRD_PARTY_INCLUDES_END
+
+namespace zen {
+
+#if ZEN_PLATFORM_LINUX
+const bool bNoZombieChildren = []() {
+	// When a child process exits it is put into a zombie state until the parent
+	// collects its result. This doesn't fit the Windows-like model that Zen uses
+	// where there is a less strict familial model and no zombification. Ignoring
+	// SIGCHLD signals removes the need to call wait() on zombies. Another option
+	// would be for the child to call setsid() but that would detatch the child
+	// from the terminal.
+	struct sigaction Action = {};
+	sigemptyset(&Action.sa_mask);
+	Action.sa_handler = SIG_IGN;
+	sigaction(SIGCHLD, &Action, nullptr);
+	return true;
+}();
+#endif
+
+ProcessHandle::ProcessHandle() = default;
+
+#if ZEN_PLATFORM_WINDOWS
+void
+ProcessHandle::Initialize(void* ProcessHandle)
+{
+	ZEN_ASSERT(m_ProcessHandle == nullptr);
+
+	if (ProcessHandle == INVALID_HANDLE_VALUE)
+	{
+		ProcessHandle = nullptr;
+	}
+
+	// TODO: perform some debug verification here to verify it's a valid handle?
+	m_ProcessHandle = ProcessHandle;
+	m_Pid			= GetProcessId(m_ProcessHandle);
+}
+#endif	// ZEN_PLATFORM_WINDOWS
+
+ProcessHandle::~ProcessHandle()
+{
+	Reset();
+}
+
+void
+ProcessHandle::Initialize(int Pid)
+{
+	ZEN_ASSERT(m_ProcessHandle == nullptr);
+
+#if ZEN_PLATFORM_WINDOWS
+	m_ProcessHandle = OpenProcess(PROCESS_QUERY_INFORMATION | SYNCHRONIZE, FALSE, Pid);
+#elif ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
+	if (Pid > 0)
+	{
+		m_ProcessHandle = (void*)(intptr_t(Pid));
+	}
+#endif
+
+	if (!m_ProcessHandle)
+	{
+		ThrowLastError(fmt::format("ProcessHandle::Initialize(pid: {}) failed", Pid));
+	}
+
+	m_Pid = Pid;
+}
+
+bool
+ProcessHandle::IsRunning() const
+{
+	bool bActive = false;
+
+#if ZEN_PLATFORM_WINDOWS
+	DWORD ExitCode = 0;
+	GetExitCodeProcess(m_ProcessHandle, &ExitCode);
+	bActive = (ExitCode == STILL_ACTIVE);
+#elif ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
+	bActive = (kill(pid_t(m_Pid), 0) == 0);
+#endif
+
+	return bActive;
+}
+
+bool
+ProcessHandle::IsValid() const
+{
+	return (m_ProcessHandle != nullptr);
+}
+
+void
+ProcessHandle::Terminate(int ExitCode)
+{
+	if (!IsRunning())
+	{
+		return;
+	}
+
+	bool bSuccess = false;
+
+#if ZEN_PLATFORM_WINDOWS
+	TerminateProcess(m_ProcessHandle, ExitCode);
+	DWORD WaitResult = WaitForSingleObject(m_ProcessHandle, INFINITE);
+	bSuccess		 = (WaitResult != WAIT_OBJECT_0);
+#elif ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
+	ZEN_UNUSED(ExitCode);
+	bSuccess			= (kill(m_Pid, SIGKILL) == 0);
+#endif
+
+	if (!bSuccess)
+	{
+		// What might go wrong here, and what is meaningful to act on?
+	}
+}
+
+void
+ProcessHandle::Reset()
+{
+	if (IsValid())
+	{
+#if ZEN_PLATFORM_WINDOWS
+		CloseHandle(m_ProcessHandle);
+#endif
+		m_ProcessHandle = nullptr;
+		m_Pid			= 0;
+	}
+}
+
+bool
+ProcessHandle::Wait(int TimeoutMs)
+{
+	using namespace std::literals;
+
+#if ZEN_PLATFORM_WINDOWS
+	const DWORD Timeout = (TimeoutMs < 0) ? INFINITE : TimeoutMs;
+
+	const DWORD WaitResult = WaitForSingleObject(m_ProcessHandle, Timeout);
+
+	switch (WaitResult)
+	{
+		case WAIT_OBJECT_0:
+			return true;
+
+		case WAIT_TIMEOUT:
+			return false;
+
+		case WAIT_FAILED:
+			break;
+	}
+#elif ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
+	const int SleepMs	= 20;
+	timespec  SleepTime = {0, SleepMs * 1000 * 1000};
+	for (int SleepedTimeMS = 0;; SleepedTimeMS += SleepMs)
+	{
+		int WaitState = 0;
+		waitpid(m_Pid, &WaitState, WNOHANG | WCONTINUED | WUNTRACED);
+
+		if (kill(m_Pid, 0) < 0)
+		{
+			int32_t LastError = zen::GetLastError();
+			if (LastError == ESRCH)
+			{
+				return true;
+			}
+			ThrowSystemError(static_cast<uint32_t>(LastError), "Process::Wait kill failed"sv);
+		}
+
+		if (TimeoutMs >= 0 && SleepedTimeMS >= TimeoutMs)
+		{
+			return false;
+		}
+
+		nanosleep(&SleepTime, nullptr);
+	}
+#endif
+
+	// What might go wrong here, and what is meaningful to act on?
+	ThrowLastError("Process::Wait failed"sv);
+}
+
+int
+ProcessHandle::WaitExitCode()
+{
+	Wait(-1);
+
+#if ZEN_PLATFORM_WINDOWS
+	DWORD ExitCode = 0;
+	GetExitCodeProcess(m_ProcessHandle, &ExitCode);
+
+	ZEN_ASSERT(ExitCode != STILL_ACTIVE);
+
+	return ExitCode;
+#else
+	ZEN_NOT_IMPLEMENTED();
+
+	return 0;
+#endif
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+#if !ZEN_PLATFORM_WINDOWS || ZEN_WITH_TESTS
+static void
+BuildArgV(std::vector<char*>& Out, char* CommandLine)
+{
+	char* Cursor = CommandLine;
+	while (true)
+	{
+		// Skip leading whitespace
+		for (; *Cursor == ' '; ++Cursor)
+			;
+
+		// Check for nullp terminator
+		if (*Cursor == '\0')
+		{
+			break;
+		}
+
+		Out.push_back(Cursor);
+
+		// Extract word
+		int QuoteCount = 0;
+		do
+		{
+			QuoteCount += (*Cursor == '\"');
+			if (*Cursor == ' ' && !(QuoteCount & 1))
+			{
+				break;
+			}
+			++Cursor;
+		} while (*Cursor != '\0');
+
+		if (*Cursor == '\0')
+		{
+			break;
+		}
+
+		*Cursor = '\0';
+		++Cursor;
+	}
+}
+#endif	// !WINDOWS || TESTS
+
+#if ZEN_PLATFORM_WINDOWS
+static CreateProcResult
+CreateProcNormal(const std::filesystem::path& Executable, std::string_view CommandLine, const CreateProcOptions& Options)
+{
+	PROCESS_INFORMATION ProcessInfo{};
+	STARTUPINFO			StartupInfo{.cb = sizeof(STARTUPINFO)};
+
+	const bool			  InheritHandles	= false;
+	void*				  Environment		= nullptr;
+	LPSECURITY_ATTRIBUTES ProcessAttributes = nullptr;
+	LPSECURITY_ATTRIBUTES ThreadAttributes	= nullptr;
+
+	DWORD CreationFlags = 0;
+	if (Options.Flags & CreateProcOptions::Flag_NewConsole)
+	{
+		CreationFlags |= CREATE_NEW_CONSOLE;
+	}
+
+	const wchar_t* WorkingDir = nullptr;
+	if (Options.WorkingDirectory != nullptr)
+	{
+		WorkingDir = Options.WorkingDirectory->c_str();
+	}
+
+	ExtendableWideStringBuilder<256> CommandLineZ;
+	CommandLineZ << CommandLine;
+
+	BOOL Success = CreateProcessW(Executable.c_str(),
+								  CommandLineZ.Data(),
+								  ProcessAttributes,
+								  ThreadAttributes,
+								  InheritHandles,
+								  CreationFlags,
+								  Environment,
+								  WorkingDir,
+								  &StartupInfo,
+								  &ProcessInfo);
+
+	if (!Success)
+	{
+		return nullptr;
+	}
+
+	CloseHandle(ProcessInfo.hThread);
+	return ProcessInfo.hProcess;
+}
+
+static CreateProcResult
+CreateProcUnelevated(const std::filesystem::path& Executable, std::string_view CommandLine, const CreateProcOptions& Options)
+{
+	/* Launches a binary with the shell as its parent. The shell (such as
+	   Explorer) should be an unelevated process. */
+
+	// No sense in using this route if we are not elevated in the first place
+	if (IsUserAnAdmin() == FALSE)
+	{
+		return CreateProcNormal(Executable, CommandLine, Options);
+	}
+
+	// Get the users' shell process and open it for process creation
+	HWND ShellWnd = GetShellWindow();
+	if (ShellWnd == nullptr)
+	{
+		return nullptr;
+	}
+
+	DWORD ShellPid;
+	GetWindowThreadProcessId(ShellWnd, &ShellPid);
+
+	HANDLE Process = OpenProcess(PROCESS_CREATE_PROCESS, FALSE, ShellPid);
+	if (Process == nullptr)
+	{
+		return nullptr;
+	}
+	auto $0 = MakeGuard([&] { CloseHandle(Process); });
+
+	// Creating a process as a child of another process is done by setting a
+	// thread-attribute list on the startup info passed to CreateProcess()
+	SIZE_T AttrListSize;
+	InitializeProcThreadAttributeList(nullptr, 1, 0, &AttrListSize);
+
+	auto AttrList = (PPROC_THREAD_ATTRIBUTE_LIST)malloc(AttrListSize);
+	auto $1		  = MakeGuard([&] { free(AttrList); });
+
+	if (!InitializeProcThreadAttributeList(AttrList, 1, 0, &AttrListSize))
+	{
+		return nullptr;
+	}
+
+	BOOL bOk =
+		UpdateProcThreadAttribute(AttrList, 0, PROC_THREAD_ATTRIBUTE_PARENT_PROCESS, (HANDLE*)&Process, sizeof(Process), nullptr, nullptr);
+	if (!bOk)
+	{
+		return nullptr;
+	}
+
+	// By this point we know we are an elevated process. It is not allowed to
+	// create a process as a child of another unelevated process that share our
+	// elevated console window if we have one. So we'll need to create a new one.
+	uint32_t CreateProcFlags = EXTENDED_STARTUPINFO_PRESENT;
+	if (GetConsoleWindow() != nullptr)
+	{
+		CreateProcFlags |= CREATE_NEW_CONSOLE;
+	}
+	else
+	{
+		CreateProcFlags |= DETACHED_PROCESS;
+	}
+
+	// Everything is set up now so we can proceed and launch the process
+	STARTUPINFOEXW StartupInfo = {
+		.StartupInfo	 = {.cb = sizeof(STARTUPINFOEXW)},
+		.lpAttributeList = AttrList,
+	};
+	PROCESS_INFORMATION ProcessInfo = {};
+
+	if (Options.Flags & CreateProcOptions::Flag_NewConsole)
+	{
+		CreateProcFlags |= CREATE_NEW_CONSOLE;
+	}
+
+	ExtendableWideStringBuilder<256> CommandLineZ;
+	CommandLineZ << CommandLine;
+
+	bOk = CreateProcessW(Executable.c_str(),
+						 CommandLineZ.Data(),
+						 nullptr,
+						 nullptr,
+						 FALSE,
+						 CreateProcFlags,
+						 nullptr,
+						 nullptr,
+						 &StartupInfo.StartupInfo,
+						 &ProcessInfo);
+	if (bOk == FALSE)
+	{
+		return nullptr;
+	}
+
+	CloseHandle(ProcessInfo.hThread);
+	return ProcessInfo.hProcess;
+}
+
+static CreateProcResult
+CreateProcElevated(const std::filesystem::path& Executable, std::string_view CommandLine, const CreateProcOptions& Options)
+{
+	ExtendableWideStringBuilder<256> CommandLineZ;
+	CommandLineZ << CommandLine;
+
+	SHELLEXECUTEINFO ShellExecuteInfo;
+	ZeroMemory(&ShellExecuteInfo, sizeof(ShellExecuteInfo));
+	ShellExecuteInfo.cbSize		  = sizeof(ShellExecuteInfo);
+	ShellExecuteInfo.fMask		  = SEE_MASK_UNICODE | SEE_MASK_NOCLOSEPROCESS;
+	ShellExecuteInfo.lpFile		  = Executable.c_str();
+	ShellExecuteInfo.lpVerb		  = TEXT("runas");
+	ShellExecuteInfo.nShow		  = SW_SHOW;
+	ShellExecuteInfo.lpParameters = CommandLineZ.c_str();
+
+	if (Options.WorkingDirectory != nullptr)
+	{
+		ShellExecuteInfo.lpDirectory = Options.WorkingDirectory->c_str();
+	}
+
+	if (::ShellExecuteEx(&ShellExecuteInfo))
+	{
+		return ShellExecuteInfo.hProcess;
+	}
+
+	return nullptr;
+}
+#endif	// ZEN_PLATFORM_WINDOWS
+
+CreateProcResult
+CreateProc(const std::filesystem::path& Executable, std::string_view CommandLine, const CreateProcOptions& Options)
+{
+#if ZEN_PLATFORM_WINDOWS
+	if (Options.Flags & CreateProcOptions::Flag_Unelevated)
+	{
+		return CreateProcUnelevated(Executable, CommandLine, Options);
+	}
+
+	if (Options.Flags & CreateProcOptions::Flag_Elevated)
+	{
+		return CreateProcElevated(Executable, CommandLine, Options);
+	}
+
+	return CreateProcNormal(Executable, CommandLine, Options);
+#else
+	std::vector<char*> ArgV;
+	std::string		   CommandLineZ(CommandLine);
+	BuildArgV(ArgV, CommandLineZ.data());
+	ArgV.push_back(nullptr);
+
+	int ChildPid = fork();
+	if (ChildPid < 0)
+	{
+		ThrowLastError("Failed to fork a new child process");
+	}
+	else if (ChildPid == 0)
+	{
+		if (Options.WorkingDirectory != nullptr)
+		{
+			int Result = chdir(Options.WorkingDirectory->c_str());
+			ZEN_UNUSED(Result);
+		}
+
+		if (execv(Executable.c_str(), ArgV.data()) < 0)
+		{
+			ThrowLastError("Failed to exec() a new process image");
+		}
+	}
+
+	return ChildPid;
+#endif
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+ProcessMonitor::ProcessMonitor()
+{
+}
+
+ProcessMonitor::~ProcessMonitor()
+{
+	RwLock::ExclusiveLockScope _(m_Lock);
+
+	for (HandleType& Proc : m_ProcessHandles)
+	{
+#if ZEN_PLATFORM_WINDOWS
+		CloseHandle(Proc);
+#endif
+		Proc = 0;
+	}
+}
+
+bool
+ProcessMonitor::IsRunning()
+{
+	RwLock::ExclusiveLockScope _(m_Lock);
+
+	bool FoundOne = false;
+
+	for (HandleType& Proc : m_ProcessHandles)
+	{
+		bool ProcIsActive;
+
+#if ZEN_PLATFORM_WINDOWS
+		DWORD ExitCode = 0;
+		GetExitCodeProcess(Proc, &ExitCode);
+
+		ProcIsActive = (ExitCode == STILL_ACTIVE);
+		if (!ProcIsActive)
+		{
+			CloseHandle(Proc);
+		}
+#else
+		int Pid		 = int(intptr_t(Proc));
+		ProcIsActive = IsProcessRunning(Pid);
+#endif
+
+		if (!ProcIsActive)
+		{
+			Proc = 0;
+		}
+
+		// Still alive
+		FoundOne |= ProcIsActive;
+	}
+
+	std::erase_if(m_ProcessHandles, [](HandleType Handle) { return Handle == 0; });
+
+	return FoundOne;
+}
+
+void
+ProcessMonitor::AddPid(int Pid)
+{
+	HandleType ProcessHandle;
+
+#if ZEN_PLATFORM_WINDOWS
+	ProcessHandle = OpenProcess(PROCESS_QUERY_INFORMATION | SYNCHRONIZE, FALSE, Pid);
+#else
+	ProcessHandle = HandleType(intptr_t(Pid));
+#endif
+
+	if (ProcessHandle)
+	{
+		RwLock::ExclusiveLockScope _(m_Lock);
+		m_ProcessHandles.push_back(ProcessHandle);
+	}
+}
+
+bool
+ProcessMonitor::IsActive() const
+{
+	RwLock::SharedLockScope _(m_Lock);
+	return m_ProcessHandles.empty() == false;
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+bool
+IsProcessRunning(int pid)
+{
+	// This function is arguably not super useful, a pid can be re-used
+	// by the OS so holding on to a pid and polling it over some time
+	// period will not necessarily tell you what you probably want to know.
+
+#if ZEN_PLATFORM_WINDOWS
+	HANDLE hProc = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, pid);
+
+	if (!hProc)
+	{
+		DWORD Error = zen::GetLastError();
+
+		if (Error == ERROR_INVALID_PARAMETER)
+		{
+			return false;
+		}
+
+		ThrowSystemError(Error, fmt::format("failed to open process with pid {}", pid));
+	}
+
+	bool  bStillActive = true;
+	DWORD ExitCode	   = 0;
+	if (0 != GetExitCodeProcess(hProc, &ExitCode))
+	{
+		bStillActive = ExitCode == STILL_ACTIVE;
+	}
+	else
+	{
+		ZEN_WARN("Unable to get exit code from handle for process '{}', treating the process as active", pid);
+	}
+
+	CloseHandle(hProc);
+
+	return bStillActive;
+#elif ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
+	return (kill(pid_t(pid), 0) == 0);
+#endif
+}
+
+int
+GetCurrentProcessId()
+{
+#if ZEN_PLATFORM_WINDOWS
+	return ::GetCurrentProcessId();
+#else
+	return int(getpid());
+#endif
+}
+
+int
+GetProcessId(CreateProcResult ProcId)
+{
+#if ZEN_PLATFORM_WINDOWS
+	return static_cast<int>(::GetProcessId(ProcId));
+#else
+	return ProcId;
+#endif
+}
+
+#if ZEN_WITH_TESTS
+
+void
+process_forcelink()
+{
+}
+
+TEST_SUITE_BEGIN("core.process");
+
+TEST_CASE("Process")
+{
+	int Pid = GetCurrentProcessId();
+	CHECK(Pid > 0);
+	CHECK(IsProcessRunning(Pid));
+}
+
+TEST_CASE("BuildArgV")
+{
+	const char* Words[] = {"one", "two", "three", "four", "five"};
+	struct
+	{
+		int			WordCount;
+		const char* Input;
+	} Cases[] = {
+		{0, ""},
+		{0, "  "},
+		{1, "one"},
+		{1, " one"},
+		{1, "one  "},
+		{2, "one two"},
+		{2, " one two"},
+		{2, "one two "},
+		{2, " one two"},
+		{2, "one two "},
+		{2, "one two "},
+		{3, "one two three"},
+		{3, "\"one\" two \"three\""},
+		{5, "one two three four five"},
+	};
+
+	for (const auto& Case : Cases)
+	{
+		std::vector<char*> OutArgs;
+		StringBuilder<64>  Mutable;
+		Mutable << Case.Input;
+		BuildArgV(OutArgs, Mutable.Data());
+
+		CHECK_EQ(OutArgs.size(), Case.WordCount);
+
+		for (int i = 0, n = int(OutArgs.size()); i < n; ++i)
+		{
+			const char* Truth	 = Words[i];
+			size_t		TruthLen = strlen(Truth);
+
+			const char* Candidate = OutArgs[i];
+			bool		bQuoted	  = (Candidate[0] == '\"');
+			Candidate += bQuoted;
+
+			CHECK(strncmp(Truth, Candidate, TruthLen) == 0);
+
+			if (bQuoted)
+			{
+				CHECK_EQ(Candidate[TruthLen], '\"');
+			}
+		}
+	}
+}
+
+TEST_SUITE_END(/* core.process */);
+
+#endif
+
+}  // namespace zen