Hello,
I'm experiencing some difference in behavior between Windows 10 2004 and earlier versions.
Here's my scenario:
I'm creating an MSIX package for my application. I want my main executable and all of its child processes to run inside the MSIX container. According to the docs here, this supposed to be the default behavior. However, in my testing on Windows 10 1909 I found this to be NOT the case. So I created a little executable that simply calls CreateProcess with the PROCESS_CREATION_DESKTOP_APP_BREAKAWAY_DISABLE_PROCESS_TREE flag. This executable is pointed by my start menu shortcut. This fixed my problem on Win10 1909. My child processes happily run inside the container.
As an aside, the MSIX documentation above and the Win32 documentation appears to be in conflict:
The win32 documentation states:
PROCESS_CREATION_DESKTOP_APP_BREAKAWAY_ENABLE_PROCESS_TREE 0x01
The process being created will create any child processes outside of the desktop app runtime environment. This behavior is the default for processes for which no policy has been set.
So if break-away is the default then child processes will NOT run inside a container.
Back the the real problem: on Windows 10 2004 my little launcher app does not work at all. Calling CreateProcess with PROCESS_CREATION_DESKTOP_APP_BREAKAWAY_DISABLE_PROCESS_TREE has the exact opposite affect than what's documented. The child process "breaks away" and does not see the files inside the container. If I use "null" attribute list, then I get the behavior I want.
Can anybody confirm this confusing variety of documentation and behaviors?
Here's the code for my launcher:
#include <iostream>
#include <cassert>
#include <vector>
#include <string>
#include <regex>
#define NTDDI_VERSION NTDDI_WIN10_RS2
#include <Windows.h>
#define ASSERT assert
LPPROC_THREAD_ATTRIBUTE_LIST MakeAttributeList()
{
LPPROC_THREAD_ATTRIBUTE_LIST attrbuteList;
SIZE_T AttributeListSize{};
InitializeProcThreadAttributeList(nullptr, 1, 0, &AttributeListSize);
attrbuteList = (LPPROC_THREAD_ATTRIBUTE_LIST)HeapAlloc(
GetProcessHeap(),
0,
AttributeListSize
);
DWORD error = 0;
if (!InitializeProcThreadAttributeList(
attrbuteList,
1,
0,
&AttributeListSize))
throw GetLastError();
DWORD attribute = PROCESS_CREATION_DESKTOP_APP_BREAKAWAY_DISABLE_PROCESS_TREE;
if (!UpdateProcThreadAttribute(
attrbuteList,
0,
PROC_THREAD_ATTRIBUTE_DESKTOP_APP_POLICY,
&attribute,
sizeof(attribute),
nullptr,
nullptr))
throw GetLastError();
return attrbuteList;
}
int wWinMain(
HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPWSTR lpCmdLine,
int nShowCmd)
{
try
{
const int len = 4096;
wchar_t buf[len];
if (len == GetModuleFileName(0, buf, len))
throw GetLastError();
auto fname = std::regex_replace(buf, std::wregex(L"msixlauncher\\.exe"), L"dwgviewr.exe");
STARTUPINFOEXW startup_info = {};
PROCESS_INFORMATION process_info = {};
startup_info.StartupInfo.cb = sizeof(startup_info);
startup_info.lpAttributeList = MakeAttributeList();
if (!::CreateProcess(
fname.c_str(),
nullptr,
nullptr,
nullptr,
false,
EXTENDED_STARTUPINFO_PRESENT,
nullptr,
nullptr,
(STARTUPINFO*)&startup_info, // startup info
&process_info // process info
))
throw GetLastError();
WaitForSingleObject(process_info.hProcess, INFINITE);
::CloseHandle(process_info.hProcess);
::CloseHandle(process_info.hThread);
}
catch (DWORD err)
{
return err;
}
return 0;
}
