Understanding NT

Listing 3: main.c — Demonstration program

// main.c

#define UNICODE
#define _UNICODE

#include <windows.h>
#include <tchar.h>
#include <stdio.h>
#include "symlink.h"

#define A_PATH          TEXT("Software\\PaulaT\\A")
#define B_PATH          TEXT("Software\\PaulaT\\B")
#define CURRENT_PATH    TEXT("Software\\PaulaT\\Current")
#define CURRENT_KEY     TEXT("Current")
#define PAULAT          TEXT("Software\\PaulaT")

//-----------------------------------------------------------------
int main(void)
{
    HKEY hKey = NULL;
    DWORD status, t, s, dw = 0, dw2 = 0;
    TCHAR sz[MAX_PATH];

    // Create some keys to test symbolic links with

    status = RegCreateKeyEx(HKEY_LOCAL_MACHINE, A_PATH, 0, NULL, 
                            REG_OPTION_NON_VOLATILE, 
                            KEY_ALL_ACCESS, 0, &hKey, 0);
    if (status == ERROR_SUCCESS) {
        dw = 1;
        RegSetValueEx(hKey,TEXT("Val1"),0,REG_SZ,
                      (LPBYTE)TEXT("AAA"), 8);
        RegSetValueEx(hKey,TEXT("Val2"),0,REG_DWORD,(LPBYTE)&dw,4);
        RegCloseKey(hKey);
    }

    status = RegCreateKeyEx(HKEY_LOCAL_MACHINE, B_PATH, 0, NULL, 
                            REG_OPTION_NON_VOLATILE, 
                            KEY_ALL_ACCESS, 0, &hKey, 0);
    if (status == ERROR_SUCCESS) {
        dw = 2;
        RegSetValueEx(hKey,TEXT("Val1"),0,REG_SZ,
                      (LPBYTE)TEXT("BBB"), 8);
        RegSetValueEx(hKey,TEXT("Val2"),0,REG_DWORD,(LPBYTE)&dw,4);
        RegCloseKey(hKey);
    }

    // Create a symbolic link key named "Current"

    status = CreateSymLinkKey(HKEY_LOCAL_MACHINE, PAULAT, 
                              CURRENT_KEY, &hKey);

    // Set the symbolic link key to key "A"

    SetSymLink(hKey, HKEY_LOCAL_MACHINE, A_PATH);
    RegCloseKey(hKey);

    // Test symbolic link by reading values

    status = RegOpenKeyEx(HKEY_LOCAL_MACHINE, CURRENT_PATH, 0, 
                          KEY_READ, &hKey);

    if (status == ERROR_SUCCESS) {
        s = MAX_PATH * sizeof(TCHAR);
        RegQueryValueEx(hKey,TEXT("Val1"),0,&t,(LPBYTE)sz,&s);

        s = sizeof(DWORD);
        RegQueryValueEx(hKey,TEXT("Val2"),0,&t,(LPBYTE)&dw2,&s);

        _tprintf(TEXT("Val1 = %s, Val2 = %d\n"), sz, dw2);
        RegCloseKey(hKey);
    }

    // Reopen the symbolic link and reset it to different key

    status = OpenSymLink(HKEY_LOCAL_MACHINE, CURRENT_PATH, &hKey);
    
    if (status == ERROR_SUCCESS) {
        SetSymLink(hKey, HKEY_LOCAL_MACHINE, B_PATH);
    }

    // Test symbolic link by reading values

    status = RegOpenKeyEx(HKEY_LOCAL_MACHINE, CURRENT_PATH, 0, 
                          KEY_READ, &hKey);

    if (status == ERROR_SUCCESS) {
        s = MAX_PATH * sizeof(TCHAR);
        RegQueryValueEx(hKey,TEXT("Val1"),0,&t,(LPBYTE)sz,&s);

        s = sizeof(DWORD);
        RegQueryValueEx(hKey,TEXT("Val2"),0,&t,(LPBYTE)&dw2,&s);

        _tprintf(TEXT("Val1 = %s, Val2 = %d\n"), sz, dw2);
        RegCloseKey(hKey);
    }

    // Now try deleting the Symbolic link key (not the key it points to)

    DeleteSymLink(HKEY_LOCAL_MACHINE, CURRENT_PATH);
    return TRUE;

} // main

//End of File