make_case_sensitive_directory.cpp

#define WIN32_LEAN_AND_MEAN
#define _ATL_NO_AUTOMATIC_NAMESPACE
#include <windows.h>
#include <atlbase.h>
#include <winternl.h>
#include <cstdio>
#include <cstdlib>
#pragma comment(lib, "ntdll")

#ifndef FILE_CS_FLAG_CASE_SENSITIVE_DIR
#define FILE_CS_FLAG_CASE_SENSITIVE_DIR 0x00000001
#endif
#define FileCaseSensitiveInformation (FILE_INFORMATION_CLASS)71
typedef struct {
	ULONG Flags;
} FILE_CASE_SENSITIVE_INFORMATION, *PFILE_CASE_SENSITIVE_INFORMATION;

EXTERN_C NTSTATUS NTSYSAPI NTAPI NtSetInformationFile(
	_In_  HANDLE                 FileHandle,
	_Out_ PIO_STATUS_BLOCK       IoStatusBlock,
	_In_  PVOID                  FileInformation,
	_In_  ULONG                  Length,
	_In_  FILE_INFORMATION_CLASS FileInformationClass
);

int __cdecl wmain(int, PWSTR argv[])
{
	ATL::CHandle d(CreateFileW(argv[1], FILE_WRITE_ATTRIBUTES, 0, nullptr, CREATE_NEW, FILE_ATTRIBUTE_DIRECTORY | FILE_FLAG_POSIX_SEMANTICS | FILE_FLAG_BACKUP_SEMANTICS, nullptr));
	if (d == INVALID_HANDLE_VALUE)
	{
		printf("CreateFile %08lx\n", GetLastError());
		d.Detach();
		return EXIT_FAILURE;
	}
	IO_STATUS_BLOCK iob;
	FILE_CASE_SENSITIVE_INFORMATION file_cs = { FILE_CS_FLAG_CASE_SENSITIVE_DIR };
	NTSTATUS status = NtSetInformationFile(d, &iob, &file_cs, sizeof file_cs, FileCaseSensitiveInformation);
	if (NT_ERROR(status))
	{
		printf("NtSetInformationFile %08lx\n", status);
		return EXIT_FAILURE;
	}
}

make_case_sensitive_directory_sdk.cpp

#define WIN32_LEAN_AND_MEAN
#define _ATL_NO_AUTOMATIC_NAMESPACE
#include <windows.h>
#include <atlbase.h>
#include <cstdio>
#include <cstdlib>

int __cdecl wmain(int, PWSTR argv[])
{
	ATL::CHandle d(CreateFileW(argv[1], FILE_WRITE_ATTRIBUTES, 0, nullptr, CREATE_NEW, FILE_ATTRIBUTE_DIRECTORY | FILE_FLAG_POSIX_SEMANTICS | FILE_FLAG_BACKUP_SEMANTICS, nullptr));
	if (d == INVALID_HANDLE_VALUE)
	{
		printf("CreateFile %08lx\n", GetLastError());
		d.Detach();
		return EXIT_FAILURE;
	}
	FILE_CASE_SENSITIVE_INFO file_cs = { FILE_CS_FLAG_CASE_SENSITIVE_DIR };
	if (!SetFileInformationByHandle(d, FileCaseSensitiveInfo, &file_cs, sizeof file_cs))
	{
		printf("SetFileInformationByHandle %08lx\n", GetLastError());
		return EXIT_FAILURE;
	}
}

mark_directory_as_case_sensitive.cpp

#define WIN32_LEAN_AND_MEAN
#define _ATL_NO_AUTOMATIC_NAMESPACE
#include <windows.h>
#include <atlbase.h>
#include <winternl.h>
#include <cstdio>
#include <cstdlib>
#pragma comment(lib, "ntdll")

#ifndef FILE_CS_FLAG_CASE_SENSITIVE_DIR
#define FILE_CS_FLAG_CASE_SENSITIVE_DIR 0x00000001
#endif
#define FileCaseSensitiveInformation (FILE_INFORMATION_CLASS)71
typedef struct {
	ULONG Flags;
} FILE_CASE_SENSITIVE_INFORMATION, *PFILE_CASE_SENSITIVE_INFORMATION;

EXTERN_C NTSTATUS NTSYSAPI NTAPI NtSetInformationFile(
	_In_  HANDLE                 FileHandle,
	_Out_ PIO_STATUS_BLOCK       IoStatusBlock,
	_In_  PVOID                  FileInformation,
	_In_  ULONG                  Length,
	_In_  FILE_INFORMATION_CLASS FileInformationClass
);

int __cdecl wmain(int, PWSTR argv[])
{
	ATL::CHandle d(CreateFileW(argv[1], FILE_WRITE_ATTRIBUTES, FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, nullptr));
	if (d == INVALID_HANDLE_VALUE)
	{
		printf("CreateFile %08lx\n", GetLastError());
		d.Detach();
		return EXIT_FAILURE;
	}
	IO_STATUS_BLOCK iob;
	FILE_CASE_SENSITIVE_INFORMATION file_cs = { FILE_CS_FLAG_CASE_SENSITIVE_DIR };
	NTSTATUS status = NtSetInformationFile(d, &iob, &file_cs, sizeof file_cs, FileCaseSensitiveInformation);
	if (NT_ERROR(status))
	{
		printf("NtSetInformationFile %08lx\n", status);
		return EXIT_FAILURE;
	}
}

mark_directory_as_case_sensitive_sdk.cpp

#define WIN32_LEAN_AND_MEAN
#define _ATL_NO_AUTOMATIC_NAMESPACE
#include <windows.h>
#include <atlbase.h>
#include <cstdio>
#include <cstdlib>

int __cdecl wmain(int, PWSTR argv[])
{
	ATL::CHandle d(CreateFileW(argv[1], FILE_WRITE_ATTRIBUTES, FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, nullptr));
	if (d == INVALID_HANDLE_VALUE)
	{
		printf("CreateFile %08lx\n", GetLastError());
		d.Detach();
		return EXIT_FAILURE;
	}
	FILE_CASE_SENSITIVE_INFO file_cs = { FILE_CS_FLAG_CASE_SENSITIVE_DIR };
	if (!SetFileInformationByHandle(d, FileCaseSensitiveInfo, &file_cs, sizeof file_cs))
	{
		printf("SetFileInformationByHandle %08lx\n", GetLastError());
		return EXIT_FAILURE;
	}
}