Understanding NT
By Paula Tomlinson, February 01, 2001
The NT and W2K can create "symbolic links in the registry - registry keys that are actually just synonyms for some other key in the registry tree. HKEY_CURRENT_USER is a good example of such a symbolic link. Can your program create symbolic links in the registry as well? Yes, but you'll need a bit of undocumented information that this column provides.
February 2001/Understanding NT/Listing 1
// symlink.c
#define UNICODE
#define _UNICODE
#include <windows.h>
#include "symlink.h"
DWORD CreateSymLinkKey(HKEY hLinkRootKey,
LPTSTR pszLinkSubKey,
LPTSTR pszLinkKey,
PHKEY phLinkKey)
{
DWORD status = 0, t = 0, size = 0;
HKEY hKey = NULL, hTempKey = NULL;
// Create (or open if already existing) the base symbolic
// link key.
status = RegCreateKeyEx(hLinkRootKey, pszLinkSubKey, 0, NULL,
REG_OPTION_NON_VOLATILE,
KEY_ALL_ACCESS, NULL, &hKey, NULL);
if (status != ERROR_SUCCESS) {
return status;
}
// Create a volatile "link" key under base subkey opened above
status = RegCreateKeyEx(hKey, pszLinkKey, 0, NULL,
REG_OPTION_VOLATILE |
REG_OPTION_CREATE_LINK,
KEY_ALL_ACCESS | KEY_CREATE_LINK,
NULL, phLinkKey, NULL);
// the symbolic link key has been created but it doesn't link
// to anything to yet
RegCloseKey(hKey);
return status;
} // CreateSymLinkKey
//-----------------------------------------------------------------
DWORD SetSymLink(HKEY hLinkKey,
HKEY hBaseRootKey,
LPTSTR pszBaseKey)
{
DWORD status = 0;
HKEY hKey = NULL;
TCHAR sz[MAX_PATH];
// Form the path to link to using kernel mode registry syntax
if (hBaseRootKey == HKEY_LOCAL_MACHINE) {
wsprintf(sz, TEXT("\\Registry\\MACHINE\\%s"), pszBaseKey);
} else if (hBaseRootKey == HKEY_USERS) {
wsprintf(sz, TEXT("\\Registry\\USER\\%s"), pszBaseKey);
} else {
return ERROR_INVALID_PARAMETER;
}
// Store the link target in the special "SymbolicLinkValue"
// REG_LINK value in the special link key to form the link.
status = RegSetValueEx(hLinkKey, L"SymbolicLinkValue", 0,
REG_LINK, (LPBYTE)sz,
lstrlen(sz) * sizeof(WCHAR));
return status;
} // SetSymLink
//End of File
