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Using System Restore

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The following examples demonstrate how to create and cancel restore points using the SRSetRestorePoint function.

The first step to using System Restore is setting up the COM calls to CoInitializeEx and CoInitializeSecurity. This is required for any process that uses the SRSetRestorePoint function. The NetworkService, LocalService, and System must be allowed make calls to the process. The following InitializeCOMSecurity function is an example of how to initialize COM security. You may need to modify the parameters to the CoInitializeSecurity function for your application.

#include <stdio.h>
#include <windows.h>
#include <accctrl.h>
#include <aclapi.h>
#include <objbase.h>
#include <strsafe.h>
#include <srrestoreptapi.h>

#pragma comment(lib, "ole32.lib")
#pragma comment(lib, "advapi32.lib")

typedef BOOL (WINAPI *PFN_SETRESTOREPTW) (PRESTOREPOINTINFOW, PSTATEMGRSTATUS);

BOOL InitializeCOMSecurity()
{   
    // Create the security descriptor explicitly as follows because
    // CoInitializeSecurity() will not accept the relative security descriptors  
    // returned by ConvertStringSecurityDescriptorToSecurityDescriptor().

    SECURITY_DESCRIPTOR securityDesc = {0};
    EXPLICIT_ACCESS   ea[5] = {0};
    ACL        *pAcl = NULL;
    ULONGLONG  rgSidBA[(SECURITY_MAX_SID_SIZE+sizeof(ULONGLONG)-1)/sizeof(ULONGLONG)]={0};
    ULONGLONG  rgSidLS[(SECURITY_MAX_SID_SIZE+sizeof(ULONGLONG)-1)/sizeof(ULONGLONG)]={0};
    ULONGLONG  rgSidNS[(SECURITY_MAX_SID_SIZE+sizeof(ULONGLONG)-1)/sizeof(ULONGLONG)]={0};
    ULONGLONG  rgSidPS[(SECURITY_MAX_SID_SIZE+sizeof(ULONGLONG)-1)/sizeof(ULONGLONG)]={0};
    ULONGLONG  rgSidSY[(SECURITY_MAX_SID_SIZE+sizeof(ULONGLONG)-1)/sizeof(ULONGLONG)]={0};
    DWORD      cbSid = 0;
    BOOL       fRet = FALSE;
    DWORD      dwRet = ERROR_SUCCESS;
    HRESULT    hrRet = S_OK;

    //
    // This creates a security descriptor that is equivalent to the following 
    // security descriptor definition language (SDDL) string:
    //
    //   O:BAG:BAD:(A;;0x1;;;LS)(A;;0x1;;;NS)(A;;0x1;;;PS)(A;;0x1;;;SY)(A;;0x1;;;BA)
    //
 
    // Initialize the security descriptor.
    fRet = ::InitializeSecurityDescriptor( &securityDesc, SECURITY_DESCRIPTOR_REVISION );
    if( !fRet )
    {
        goto exit;
    }

    // Create an administrator group security identifier (SID).
    cbSid = sizeof( rgSidBA );
    fRet = ::CreateWellKnownSid( WinBuiltinAdministratorsSid, NULL, rgSidBA, &cbSid );
    if( !fRet )
    {
        goto exit;
    }

    // Create a local service security identifier (SID).
    cbSid = sizeof( rgSidLS );
    fRet = ::CreateWellKnownSid( WinLocalServiceSid, NULL, rgSidLS, &cbSid );
    if( !fRet )
    {
        goto exit;
    }

    // Create a network service security identifier (SID).
    cbSid = sizeof( rgSidNS );
    fRet = ::CreateWellKnownSid( WinNetworkServiceSid, NULL, rgSidNS, &cbSid );
    if( !fRet )
    {
        goto exit;
    }

    // Create a personal account security identifier (SID).
    cbSid = sizeof( rgSidPS );
    fRet = ::CreateWellKnownSid( WinSelfSid, NULL, rgSidPS, &cbSid );
    if( !fRet )
    {
        goto exit;
    }

    // Create a local service security identifier (SID).
    cbSid = sizeof( rgSidSY );
    fRet = ::CreateWellKnownSid( WinLocalSystemSid, NULL, rgSidSY, &cbSid );
    if( !fRet )
    {
        goto exit;
    }

    // Setup the access control entries (ACE) for COM. You may need to modify 
    // the access permissions for your application. COM_RIGHTS_EXECUTE and
    // COM_RIGHTS_EXECUTE_LOCAL are the minimum access rights required.

    ea[0].grfAccessPermissions = COM_RIGHTS_EXECUTE | COM_RIGHTS_EXECUTE_LOCAL;
    ea[0].grfAccessMode = SET_ACCESS;
    ea[0].grfInheritance = NO_INHERITANCE;
    ea[0].Trustee.pMultipleTrustee = NULL;
    ea[0].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
    ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[0].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
    ea[0].Trustee.ptstrName = (LPTSTR)rgSidBA;

    ea[1].grfAccessPermissions = COM_RIGHTS_EXECUTE | COM_RIGHTS_EXECUTE_LOCAL;
    ea[1].grfAccessMode = SET_ACCESS;
    ea[1].grfInheritance = NO_INHERITANCE;
    ea[1].Trustee.pMultipleTrustee = NULL;
    ea[1].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
    ea[1].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[1].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
    ea[1].Trustee.ptstrName = (LPTSTR)rgSidLS;

    ea[2].grfAccessPermissions = COM_RIGHTS_EXECUTE | COM_RIGHTS_EXECUTE_LOCAL;
    ea[2].grfAccessMode = SET_ACCESS;
    ea[2].grfInheritance = NO_INHERITANCE;
    ea[2].Trustee.pMultipleTrustee = NULL;
    ea[2].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
    ea[2].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[2].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
    ea[2].Trustee.ptstrName = (LPTSTR)rgSidNS;

    ea[3].grfAccessPermissions = COM_RIGHTS_EXECUTE | COM_RIGHTS_EXECUTE_LOCAL;
    ea[3].grfAccessMode = SET_ACCESS;
    ea[3].grfInheritance = NO_INHERITANCE;
    ea[3].Trustee.pMultipleTrustee = NULL;
    ea[3].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
    ea[3].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[3].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
    ea[3].Trustee.ptstrName = (LPTSTR)rgSidPS;

    ea[4].grfAccessPermissions = COM_RIGHTS_EXECUTE | COM_RIGHTS_EXECUTE_LOCAL;
    ea[4].grfAccessMode = SET_ACCESS;
    ea[4].grfInheritance = NO_INHERITANCE;
    ea[4].Trustee.pMultipleTrustee = NULL;
    ea[4].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
    ea[4].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[4].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
    ea[4].Trustee.ptstrName = (LPTSTR)rgSidSY;

    // Create an access control list (ACL) using this ACE list.
    dwRet = ::SetEntriesInAcl( ARRAYSIZE( ea ), ea, NULL, &pAcl );
    if( dwRet != ERROR_SUCCESS || pAcl == NULL )
    {
        fRet = FALSE;
        goto exit;
    }

    // Set the security descriptor owner to Administrators.
    fRet = ::SetSecurityDescriptorOwner( &securityDesc, rgSidBA, FALSE );
    if( !fRet )
    {
        goto exit;
    }

    // Set the security descriptor group to Administrators.
    fRet = ::SetSecurityDescriptorGroup( &securityDesc, rgSidBA, FALSE );
    if( !fRet )
    {
        goto exit;
    }

    // Set the discretionary access control list (DACL) to the ACL.
    fRet = ::SetSecurityDescriptorDacl( &securityDesc, TRUE, pAcl, FALSE );
    if( !fRet )
    {
        goto exit;
    }

    // Initialize COM. You may need to modify the parameters of
    // CoInitializeSecurity() for your application. Note that an
    // explicit security descriptor is being passed down.
 
    hrRet = ::CoInitializeSecurity( &securityDesc,
                                    -1,
                                    NULL,
                                    NULL,
                                    RPC_C_AUTHN_LEVEL_PKT_PRIVACY,
                                    RPC_C_IMP_LEVEL_IDENTIFY,
                                    NULL,
                                    EOAC_DISABLE_AAA | EOAC_NO_CUSTOM_MARSHAL,
                                    NULL );
    if( FAILED( hrRet ) )
    {
        fRet = FALSE;
        goto exit;
    }

    fRet = TRUE;

 exit:

    ::LocalFree( pAcl );

    return fRet;
}

Example 1: Create a restore point.

#include <windows.h>
#include <accctrl.h>
#include <aclapi.h>
#include <objbase.h>
#include <strsafe.h>
#include <srrestoreptapi.h>

typedef BOOL (WINAPI *PFN_SETRESTOREPTW) (PRESTOREPOINTINFOW, PSTATEMGRSTATUS);

extern "C" int __cdecl wmain(int argc, WCHAR **argv)
{
   RESTOREPOINTINFOW RestorePtInfo;
   STATEMGRSTATUS SMgrStatus;
   PFN_SETRESTOREPTW fnSRSetRestorePointW=NULL;
   DWORD dwErr = ERROR_SUCCESS;
   HMODULE hSrClient = NULL;
   BOOL fRet = FALSE;
   HRESULT hr = S_OK;

   UNREFERENCED_PARAMETER(argc);
   UNREFERENCED_PARAMETER(argv);
   
   hr = CoInitializeEx( NULL, COINIT_MULTITHREADED );
   if( FAILED( hr ) )
   {
       wprintf( L"Unexpected error: CoInitializeEx() failed with 0x%08x\n", hr );
       goto exit;
   }

   // Initialize COM security to enable NetworkService,
   // LocalService and System to make callbacks to the process 
   // calling  System Restore. This is required for any process
   // that calls SRSetRestorePoint.
    
   fRet = InitializeCOMSecurity();
   if( !fRet )
   {
       wprintf( L"Unexpected error: failed to initialize COM security\n" );
       goto exit;
   }
    
   // Initialize the RESTOREPOINTINFO structure
   RestorePtInfo.dwEventType = BEGIN_SYSTEM_CHANGE;

   // Notify the system that changes are about to be made.
   // An application is to be installed.
   RestorePtInfo.dwRestorePtType = APPLICATION_INSTALL;

   // RestPtInfo.llSequenceNumber must be 0 when creating a restore point.
   RestorePtInfo.llSequenceNumber = 0;

   // String to be displayed by System Restore for this restore point.
   StringCbCopyW(RestorePtInfo.szDescription, 
            sizeof(RestorePtInfo.szDescription), 
            L"First Restore Point");
   
   // Load the DLL, which may not exist on Windows server
   hSrClient = LoadLibraryW(L"srclient.dll");
   if(NULL == hSrClient)
   {
      wprintf(L"System Restore is not present.\n");
      goto exit;
   }

   // If the library is loaded, find the entry point
   fnSRSetRestorePointW = (PFN_SETRESTOREPTW) GetProcAddress(
      hSrClient, "SRSetRestorePointW");
   if (NULL == fnSRSetRestorePointW)
   {
      wprintf(L"Failed to find SRSetRestorePointW.\n");
      goto exit;
   }

   fRet = fnSRSetRestorePointW(&RestorePtInfo, &SMgrStatus);
   if(!fRet)
   {
      dwErr = SMgrStatus.nStatus;
      if(dwErr == ERROR_SERVICE_DISABLED)
      {
         wprintf(L"System Restore is turned off.\n");
         goto exit;
      }
      wprintf(L"Failure to create the restore point; error=%u.\n", dwErr);
      goto exit;
   }

   wprintf(L"Restore point created; number=%I64d.\n", SMgrStatus.llSequenceNumber);

   // The application performs some installation operations here.

   // It is not necessary to call SrSetRestorePoint to indicate that the 
   // installation is complete except in the case of ending a nested 
   // restore point. Every BEGIN_NESTED_SYSTEM_CHANGE must have a 
   // corresponding END_NESTED_SYSTEM_CHANGE or the application cannot 
   // create new restore points.

   // Update the RESTOREPOINTINFO structure to notify the 
   // system that the operation is finished.
   RestorePtInfo.dwEventType = END_SYSTEM_CHANGE;

   // End the system change by using the sequence number 
   // received from the first call to SRSetRestorePoint.
   RestorePtInfo.llSequenceNumber = SMgrStatus.llSequenceNumber;

   // Notify the system that the operation is done and that this
   // is the end of the restore point.
   fRet = fnSRSetRestorePointW(&RestorePtInfo, &SMgrStatus);
   if(!fRet) 
   {
      dwErr = SMgrStatus.nStatus;
      wprintf(L"Failure to end the restore point; error=%u.\n", dwErr);
      goto exit;
   }

exit:

   if(hSrClient != NULL)
   {
      FreeLibrary(hSrClient);
      hSrClient = NULL;
   }

   return 0;
}

Example 2: Create and cancel a restore point.

#include <stdio.h>
#include <windows.h>
#include <accctrl.h>
#include <aclapi.h>
#include <objbase.h>
#include <strsafe.h>
#include <srrestoreptapi.h>

typedef BOOL (WINAPI *PFN_SETRESTOREPTW) (PRESTOREPOINTINFOW, PSTATEMGRSTATUS);

extern "C" int __cdecl wmain(int argc, WCHAR** argv)
{
   RESTOREPOINTINFOW RestorePtInfo;
   STATEMGRSTATUS SMgrStatus;
   PFN_SETRESTOREPTW fnSRSetRestorePointW = NULL;
   DWORD dwErr = ERROR_SUCCESS;
   HMODULE hSrClient = NULL;
   BOOL fRet = FALSE;
   HRESULT hr = S_OK;    

   UNREFERENCED_PARAMETER(argc);
   UNREFERENCED_PARAMETER(argv);
   
   hr = CoInitializeEx( NULL, COINIT_MULTITHREADED );
   if( FAILED( hr ) )
   {
       wprintf( L"Unexpected error: CoInitializeEx() failed with 0x%08x\n", hr );
       goto exit;
   }

   // Initialize COM security to enable NetworkService,
   // LocalService and System to make callbacks to the process 
   // calling  System Restore. This is required for any process
   // that calls SRSetRestorePoint.
    
   fRet = InitializeCOMSecurity();
   if( !fRet )
   {
       wprintf( L"Unexpected error: failed to initialize COM security\n" );
       goto exit;
   }
    
   // Initialize the RESTOREPOINTINFO structure.
   RestorePtInfo.dwEventType=BEGIN_SYSTEM_CHANGE;
   RestorePtInfo.dwRestorePtType=APPLICATION_INSTALL; 
   RestorePtInfo.llSequenceNumber=0;
   StringCbCopyW(RestorePtInfo.szDescription, 
            sizeof(RestorePtInfo.szDescription), 
            L"Sample Restore Point");

   // Load the DLL, which may not exist on Windows server
   hSrClient = LoadLibraryW(L"srclient.dll");
   if(NULL == hSrClient)
   {
      wprintf(L"System Restore is not present.\n");
      goto exit;
   }

   // If the library is loaded, find the entry point
   fnSRSetRestorePointW = (PFN_SETRESTOREPTW) GetProcAddress(
      hSrClient, "SRSetRestorePointW");
   if (NULL == fnSRSetRestorePointW)
   {
      wprintf(L"Failed to find SRSetRestorePointW.\n");
      goto exit;
   }

   fRet = fnSRSetRestorePointW(&RestorePtInfo, &SMgrStatus);
   if(!fRet)
   {
      dwErr = SMgrStatus.nStatus;
      if(dwErr == ERROR_SERVICE_DISABLED)
      {
         wprintf(L"System Restore is turned off.\n");
         goto exit;
      }
      wprintf(L"Failure to create the restore point; error=%u.\n", dwErr);
      goto exit;
   }

   wprintf(L"Restore point set. Restore point data:\n");
   wprintf(L"\tSequence Number=%I64d\n",SMgrStatus.llSequenceNumber);
   wprintf(L"\tStatus=%u\n",SMgrStatus.nStatus);

   // Update the structure to cancel the previous restore point.
   RestorePtInfo.dwEventType=END_SYSTEM_CHANGE;
   RestorePtInfo.dwRestorePtType=CANCELLED_OPERATION;
   // This is the sequence number returned by the previous call.
   RestorePtInfo.llSequenceNumber=SMgrStatus.llSequenceNumber; 

   // Cancel the previous restore point
   fRet = fnSRSetRestorePointW(&RestorePtInfo, &SMgrStatus);
   if(!fRet) 
   {
      dwErr = SMgrStatus.nStatus;
      wprintf(L"Failure to cancel the restore point; error=%u.\n", dwErr);
      goto exit;
   }

   wprintf(L"Restore point canceled. Restore point data:\n");
   wprintf(L"\tSequence Number=%I64d\n",SMgrStatus.llSequenceNumber);
   wprintf(L"\tStatus=%u\n",SMgrStatus.nStatus);

exit: 

   if(hSrClient != NULL)
   {
      FreeLibrary(hSrClient);
      hSrClient = NULL;
   }

   return 0;
}