Buffer Allocation With GetModuleFileNameEx - c++

Question

I am currently trying to get the full filepath from my executable by providing a process ID, and this works "fine" in the since that its able to return some of the information needed, however for some reason it becomes corrupted and this can be seen when trying to return it as a plain string: C and if you iterate over each char and print each letter you get even more of a mess. Where is my current coding wrong when attempting allocate my buffer?
std::string User::getFullPath() {
HANDLE hProcess = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, GetCurrentProcessId());
char buffer[MAX_PATH];
if (hProcess != NULL)
{
GetModuleFileNameEx(hProcess, NULL, (LPWSTR)buffer, MAX_PATH);
CloseHandle(hProcess);
}
for (char i : buffer) {
std::cout << i<<std::endl;
}
return buffer;
}
How do I properly allocate the memory in this case to prevent corruption

Answer 1

First off, the contents of your array are uninitialized if OpenProcess() fails. There is no need to use OpenProcess() on the calling process ID. Use GetCurrentProcess() instead, or simply use GetModuleFileName() instead.
That said, the real problem is not with memory allocation, but rather is that you are mixing ANSI and Unicode incorrectly. You are typecasting a char[] buffer to wchar_t*, which won't work.
You need to either:
use a wchar_t[] instead:
std::wstring User::getFullPath() {
wchar_t buffer[MAX_PATH] = {};
GetModuleFileNameW(NULL, buffer, MAX_PATH);
std::wcout << buffer << std::endl;
return buffer;
}
use GetModuleFileName(Ex)A() instead:
std::string User::getFullPath() {
char buffer[MAX_PATH] = {};
GetModuleFileNameA(NULL, buffer, MAX_PATH);
std::cout << buffer << std::endl;
return buffer;
}