#include "stdafx.h"
#include <windows.h>
 
typedef struct _REPARSE_DATA_BUFFER {
  ULONG  ReparseTag;
  USHORT  ReparseDataLength;
  USHORT  Reserved;
  union {
    struct {
      USHORT  SubstituteNameOffset;
      USHORT  SubstituteNameLength;
      USHORT  PrintNameOffset;
      USHORT  PrintNameLength;
      ULONG   Flags; // it seems that the docu is missing this entry (at least 2008-03-07)
      WCHAR  PathBuffer[1];
      } SymbolicLinkReparseBuffer;
    struct {
      USHORT  SubstituteNameOffset;
      USHORT  SubstituteNameLength;
      USHORT  PrintNameOffset;
      USHORT  PrintNameLength;
      WCHAR  PathBuffer[1];
      } MountPointReparseBuffer;
    struct {
      UCHAR  DataBuffer[1];
    } GenericReparseBuffer;
  };
} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;
 
#define REPARSE_DATA_BUFFER_HEADER_SIZE  FIELD_OFFSET(REPARSE_DATA_BUFFER, GenericReparseBuffer)
 
#define MAXIMUM_REPARSE_DATA_BUFFER_SIZE  ( 16 * 1024 )
 
int _tmain(int argc, _TCHAR* argv[])
{
  HANDLE hFile;
  LPCTSTR szMyFile = _T("C:\\Documents and Settings");  // Mount-Point (JUNCTION)
  //LPCTSTR szMyFile = _T("C:\\Users\\All Users");  // Symbolic-Link (SYMLINKD)
 
  hFile = CreateFile(szMyFile, FILE_READ_EA, FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, NULL);
  if (hFile == INVALID_HANDLE_VALUE)
  {
    _tprintf(_T("Could not open dir '%s'; error: %d\n"), szMyFile, GetLastError());
    return 1;
  }
 
  // Allocate the reparse data structure
  DWORD dwBufSize = MAXIMUM_REPARSE_DATA_BUFFER_SIZE;
  REPARSE_DATA_BUFFER* rdata;
  rdata = (REPARSE_DATA_BUFFER*) malloc(dwBufSize);
 
  // Query the reparse data
  DWORD dwRetLen;
  BOOL bRet = DeviceIoControl(hFile, FSCTL_GET_REPARSE_POINT, NULL, 0, rdata, dwBufSize, &dwRetLen, NULL);
  if (bRet == FALSE)
  {
    _tprintf(_T("DeviceIoControl failed with error: %d\n"), GetLastError());
    CloseHandle(hFile);
    return 1;
  }
  CloseHandle(hFile);
 
  if (IsReparseTagMicrosoft(rdata->ReparseTag))
  {
    if (rdata->ReparseTag == IO_REPARSE_TAG_SYMLINK)
    {
      printf("Symbolic-Link\n");
      size_t slen = rdata->SymbolicLinkReparseBuffer.SubstituteNameLength / sizeof(WCHAR);
      WCHAR *szSubName = new WCHAR[slen+1];
      wcsncpy_s(szSubName, slen+1, &rdata->SymbolicLinkReparseBuffer.PathBuffer[rdata->SymbolicLinkReparseBuffer.SubstituteNameOffset / sizeof(WCHAR)], slen);
      szSubName[slen] = 0;
      printf("SubstitutionName (len: %d): '%S'\n", rdata->SymbolicLinkReparseBuffer.SubstituteNameLength, szSubName);
      delete [] szSubName;
 
      size_t plen = rdata->SymbolicLinkReparseBuffer.PrintNameLength / sizeof(WCHAR);
      WCHAR *szPrintName = new WCHAR[plen+1];
      wcsncpy_s(szPrintName, plen+1, &rdata->SymbolicLinkReparseBuffer.PathBuffer[rdata->SymbolicLinkReparseBuffer.PrintNameOffset / sizeof(WCHAR)], plen);
      szPrintName[plen] = 0;
      printf("PrintName (len: %d): '%S'\n", rdata->SymbolicLinkReparseBuffer.PrintNameLength, szPrintName);
      delete [] szPrintName;
    }
    else if (rdata->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
    {
      printf("Mount-Point\n");
      size_t slen = rdata->MountPointReparseBuffer.SubstituteNameLength / sizeof(WCHAR);
      WCHAR *szSubName = new WCHAR[slen+1];
      wcsncpy_s(szSubName, slen+1, &rdata->MountPointReparseBuffer.PathBuffer[rdata->MountPointReparseBuffer.SubstituteNameOffset / sizeof(WCHAR)], slen);
      szSubName[slen] = 0;
      printf("SubstitutionName (len: %d): '%S'\n", rdata->MountPointReparseBuffer.SubstituteNameLength, szSubName);
      delete [] szSubName;
 
      size_t plen = rdata->MountPointReparseBuffer.PrintNameLength / sizeof(WCHAR);
      WCHAR *szPrintName = new WCHAR[plen+1];
      wcsncpy_s(szPrintName, plen+1, &rdata->MountPointReparseBuffer.PathBuffer[rdata->MountPointReparseBuffer.PrintNameOffset / sizeof(WCHAR)], plen);
      szPrintName[plen] = 0;
      printf("PrintName (len: %d): '%S'\n", rdata->MountPointReparseBuffer.PrintNameLength, szPrintName);
      delete [] szPrintName;
    }
    else
    {
      printf("No Mount-Point or Symblic-Link...\n");
    }
  }
  else
  {
    _tprintf(_T("Not a Microsoft-reparse point - could not query data!\n"));
  }
  free(rdata);
  return 0;
}