/***
*drive.c - get and change current drive
*
*       Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       This file has the _getdrive() and _chdrive() functions
*
*Revision History:
*       06-06-89  PHG   Module created, based on asm version
*       03-07-90  GJF   Made calling type _CALLTYPE1, added #include
*                       <cruntime.h> and fixed copyright. Also, cleaned up
*                       the formatting a bit.
*       07-24-90  SBM   Removed '32' from API names
*       09-27-90  GJF   New-style function declarators.
*       12-04-90  SRW   Changed to include <oscalls.h> instead of <doscalls.h>
*       12-06-90  SRW   Added _CRUISER_ and _WIN32 conditionals.
*       05-10-91  GJF   Fixed off-by-1 error in Win32 version and updated the
*                       function descriptions a bit [_WIN32_].
*       05-19-92  GJF   Revised to use the 'current directory' environment
*                       variables of Win32/NT.
*       06-09-92  GJF   Use _putenv instead of Win32 API call. Also, defer
*                       adding env var until after the successful call to
*                       change the dir/drive.
*       04-06-93  SKS   Replace _CRTAPI* with __cdecl
*       11-24-93  CFW   Rip out Cruiser.
*       11-24-93  CFW   No longer store current drive in CRT env strings.
*       02-08-95  JWM   Spliced _WIN32 & Mac versions.
*       07-01-96  GJF   Replaced defined(_WIN32) with !defined(_MAC). Also,
*                       detab-ed and cleaned up the format a bit.
*       12-17-97  GJF   Exception-safe locking.
*       05-17-99  PML   Remove all Macintosh support.
*
*******************************************************************************/

#include <cruntime.h>
#include <oscalls.h>
#include <mtdll.h>
#include <internal.h>
#include <msdos.h>
#include <errno.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>


/***
*int _getdrive() - get current drive (1=A:, 2=B:, etc.)
*
*Purpose:
*       Returns the current disk drive
*
*Entry:
*       No parameters.
*
*Exit:
*       returns 1 for A:, 2 for B:, 3 for C:, etc.
*       returns 0 if current drive cannot be determined.
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _getdrive (
        void
        )
{
        ULONG drivenum;
        UCHAR curdirstr[_MAX_PATH];

        drivenum = 0;
        if (GetCurrentDirectory(sizeof(curdirstr), curdirstr))
                if (curdirstr[1] == ':')
                        drivenum = toupper(curdirstr[0]) - 64;

        return drivenum;
}


/***
*int _chdrive(int drive) - set the current drive (1=A:, 2=B:, etc.)
*
*Purpose:
*       Allows the user to change the current disk drive
*
*Entry:
*       drive - the number of drive which should become the current drive
*
*Exit:
*       returns 0 if successful, else -1
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _chdrive (
        int drive
        )
{
        int retval;
        char  newdrive[3];

        if (drive < 1 || drive > 31) {
            errno = EACCES;
            _doserrno = ERROR_INVALID_DRIVE;
            return -1;
        }

#ifdef  _MT
        _mlock( _ENV_LOCK );
        __try {
#endif

        newdrive[0] = (char)('A' + (char)drive - (char)1);
        newdrive[1] = ':';
        newdrive[2] = '\0';

        /*
         * Set new drive. If current directory on new drive exists, it
         * will become the cwd. Otherwise defaults to root directory.
         */

        if ( SetCurrentDirectory((LPSTR)newdrive) )
            retval = 0;
        else {
            _dosmaperr(GetLastError());
            retval = -1;
        }

#ifdef  _MT
        }
        __finally {
            _munlock( _ENV_LOCK );
        }
#endif

        return retval;
}