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exec.h
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100 lines (87 loc) · 3.27 KB
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#pragma once
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <wil/resource.h>
#include <optional>
#include <string>
inline std::optional<std::string> exec_and_read_output(const std::wstring_view command, DWORD timeout_ms = 30000)
{
SECURITY_ATTRIBUTES saAttr{ sizeof(saAttr) };
saAttr.bInheritHandle = false;
constexpr size_t bufferSize = 4096;
// We must use a named pipe for async I/O
char pipename[MAX_PATH + 1];
if (!GetTempFileNameA(R"(\\.\pipe\)", "tmp", 1, pipename))
{
return std::nullopt;
}
wil::unique_handle readPipe{ CreateNamedPipeA(pipename, PIPE_ACCESS_INBOUND | FILE_FLAG_OVERLAPPED, PIPE_TYPE_BYTE | PIPE_READMODE_BYTE, PIPE_UNLIMITED_INSTANCES, bufferSize, bufferSize, 0, &saAttr) };
saAttr.bInheritHandle = true;
wil::unique_handle writePipe{ CreateFileA(pipename, GENERIC_WRITE, 0, &saAttr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr) };
if (!readPipe || !writePipe)
{
return std::nullopt;
}
PROCESS_INFORMATION piProcInfo{};
STARTUPINFOW siStartInfo{ sizeof(siStartInfo) };
siStartInfo.hStdError = writePipe.get();
siStartInfo.hStdOutput = writePipe.get();
siStartInfo.dwFlags |= STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
siStartInfo.wShowWindow = SW_HIDE;
std::wstring cmdLine{ command };
if (!CreateProcessW(nullptr,
cmdLine.data(),
nullptr,
nullptr,
true,
NORMAL_PRIORITY_CLASS | CREATE_NEW_CONSOLE,
nullptr,
nullptr,
&siStartInfo,
&piProcInfo))
{
return std::nullopt;
}
// Child process inherited the write end of the pipe, we can close it now
writePipe.reset();
auto closeProcessHandles = wil::scope_exit([&] {
CloseHandle(piProcInfo.hThread);
CloseHandle(piProcInfo.hProcess);
});
std::string childOutput;
bool processExited = false;
for (;;)
{
char buffer[bufferSize];
DWORD gotBytes = 0;
wil::unique_handle IOEvent{ CreateEventW(nullptr, true, false, nullptr) };
OVERLAPPED overlapped{ .hEvent = IOEvent.get() };
ReadFile(readPipe.get(), buffer, sizeof(buffer), nullptr, &overlapped);
const std::array<HANDLE, 2> handlesToWait = { overlapped.hEvent, piProcInfo.hProcess };
switch (WaitForMultipleObjects(1 + !processExited, handlesToWait.data(), false, timeout_ms))
{
case WAIT_OBJECT_0 + 1:
if (!processExited)
{
// When the process exits, we can reduce timeout and read the rest of the output w/o possibly big timeout
timeout_ms = 1000;
processExited = true;
closeProcessHandles.reset();
}
[[fallthrough]];
case WAIT_OBJECT_0:
if (GetOverlappedResultEx(readPipe.get(), &overlapped, &gotBytes, timeout_ms, true))
{
childOutput += std::string_view{ buffer, gotBytes };
break;
}
// Timeout
[[fallthrough]];
default:
goto exit;
}
}
exit:
CancelIo(readPipe.get());
return childOutput;
}