PRB: _getdcwd() Returns the Root Directory Under Win32s

• Microsoft Win32s versions 1.1, 1.2, 1.30, 1.30a, and 1.30c

SYMPTOMS

In the following code segment, _getdcwd() always returns the root:

   _getdcwd( 3, cBuf, MAX_PATH );
   MessageBox( hWnd, cBuf, "Drive 3 <C drive>", MB_OK );

   _chdrive( 3 );
   _getcwd( cBuf, MAX_PATH );
   MessageBox( hWnd, cbuf, "Drive 3 <C drive>", MB_OK );

CAUSE

When a Win32-based application starts on Win32s, the root is set as the current directory for any drive except the default drive.

RESOLUTION

The following code fragments work as expected under Win32s:

   _getdcwd( 0, cBuf, MAX_PATH );
   MessageBox( hWnd, cBuf, "Drive 0 <default drive>", MB_OK );

   -or-

   GetCurrentDirectory( sizeof (cBuf), cBuf );
   MessageBox( hWnd, cBuf, "SCD", MB_OK );

MORE INFORMATION

Windows NT uses the current directory of a process as the initial current directory for the current drive of a child process. So for example, if the current directory in the command prompt (CMD.EXE) is C:\WINNT then the current directory of the child process will be C:\WINNT.

However, on Win32s, the current directory for any drive except the default drive is set to the root and not the current directory of the parent process. A Win32-based application running on Win32s calling _chdrive() or SetCurrentDirectory() to change the drive GetCurrentDirectory or _getcwd() will then return the root. The _getdcwd() function is a composite of changing drives, getting the current directory of that drive, and change back to the original drive. Therefore, _getdcwd() will always return the root on Win32s.

Running the following sample to display the current directory of drives C and D under Windows NT properly displays the full path of the drive. Running the sample under Win32s always displays the root ("C:\", "D:\").

Sample Code

#include <direct.h>

   status =  _getdcwd(3, szPath, MAX_PATH);    // drive 3 == C:
   if( status != NULL )
   {
      MessageBox( hWnd, szPath, "Current working directory on C:", MB_OK );
   }

   status =  _getdcwd( 4, szPath, MAX_PATH );  // drive 4 == D:
   if( status != NULL )
   {
      MessageBox( hWnd, szPath, "Current working directory on D:", MB_OK );
   }