System API Error Handing in Linux, WIndows and Android - c++

Question

I am developing a cross platform platform that is suppose to run on the following platform
Windows x64
Linux x64
Windows ARM
Linux ARM
Android ARM
The program is used in interfacing with multiple Serial Ports (up to 20) and server connectivity using MQTT or ReST-JSON.
I am extensively suing asynchronous operation and threading in my application
I have couple question regarding error handling
Can I handle WIN API error in libc errno integer variable or do I have to use GetLastError in windows and errno in Linux + Android.
Is GetLastError() thread safe?
Is strerror_s thread safe?
Will strerror_s be available in Linux and Android if I select C11 or greater during program build?
My current implementation
//Returns the last error, in string format. Returns an empty string if there is no error.
std::string GetLastErrorAsString(void)
{
#ifdef _WIN64
//Get the error message ID, if any.
DWORD errorMessageID = ::GetLastError();
if (errorMessageID == 0)
{
return std::string(); //No error message has been recorded
}
LPSTR message_buffer = nullptr;
//Ask Win64 to give us the string version of that message ID.
//The parameters we pass in, tell Win64 to create the buffer that holds the message for us (because we don't yet know how long the message string will be).
size_t size = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
NULL, errorMessageID, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&message_buffer, 0, NULL);
//Copy the error message into a std::string.
std::string error_message(message_buffer, size);
//Free the Win64's string's buffer.
LocalFree(message_buffer);
return error_message;
#elif __linux__ || __ANDROID__
if (errno == 0)
{
return std::string(); //No error message has been recorded
}
size_t error_message_length = strerrorlen_s(errno) + 1;
std::array<char, error_message_length> error_message;
//char errmsg[errmsglen];
strerror_s(error_message.data(), error_message_length, errno);
return std::string(error_message.data());
#endif
}

Answer 1

Can I handle WIN API error in libc errno integer variable or do I have to use GetLastError in windows and errno in Linux + Android.
No, if you are calling Win APIs you will need to use GetLastError() to get the last error.
Is GetLastError() thread safe?
Yes. "Retrieves the calling thread's last-error code value. The last-error code is maintained on a per-thread basis.". Always search MSDN for information about Win API.
Is strerror_s thread safe?
In general, I don't know. A quick search found that it may be on Windows:
https://github.com/MicrosoftDocs/cpp-docs/issues/2281
Will strerror_s be available in Linux and Android if I select C11 or greater during program build?
Yes.
Always search cppreference.com for C and C++ library reference information. It clearly indicates the answer with the "since C11" in the header.