/***********************************************
 * File: LREDIR.C
 *  Program for Linux DOSEMU disk redirector functions
 * Written: 10/29/93 by Tim Bird
 *
 * NOTES:
 *  LREDIR supports the following commands:
 *  LREDIR drive filepath
 *    redirects the indicated drive to the specified linux filepath
 *    drive = the drive letter followed by a colon (ex. 'E:')
 *    filepath has linux and a file path (ex. 'LINUX\USR\SRC')
 *  LREDIR DEL drive
 *    cancels redirection of the indicated drive
 *  LREDIR
 *    shows drives that are currently redirected (mapped)
 *  LREDIR HELP or LREDIR ?
 *    show usage information for LREDIR ???
 ***********************************************/  
#include <stdio.h>    /* for printf */
#include <dos.h>    /* for geninterrupt and MK_FP */
#include <string.h>

typedef unsigned char uint8;


typedef unsigned int uint16;



#define CARRY_FLAG    1 /* carry bit in flags register */

#define CC_SUCCESS    0

#define DOS_GET_LIST_OF_LISTS 0x5200
#define DOS_GET_SDA_POINTER   0x5D06
#define DOS_GET_REDIRECTION   0x5F02
#define DOS_REDIRECT_DEVICE   0x5F03
#define DOS_CANCEL_REDIRECTION  0x5F04


#define MAX_RESOURCE_STRING_LENGTH  36  /* 16 + 16 + 3 for slashes + 1 for NULL */
#define MAX_RESOURCE_PATH_LENGTH  128 /* added to support Linux paths */
#define MAX_DEVICE_STRING_LENGTH  5 /* enough for printer strings */

#define REDIR_PRINTER_TYPE      3
#define REDIR_DISK_TYPE       4

#define READ_ONLY_DRIVE_ATTRIBUTE 1 /* same as NetWare Lite */

#define KEYWORD_DEL   "DELETE"
#define KEYWORD_DEL_COMPARE_LENGTH  3

#define DEFAULT_REDIR_PARAM   0

#define DOS_HELPER_INT        0xE6
#define DOS_HELPER_DOSEMU_CHECK   0x00

/* returns non-zero major version number if DOSEMU is loaded */ 
uint16 CheckForDOSEMU(void) 
{
  
  _AL = DOS_HELPER_DOSEMU_CHECK;
  
    geninterrupt(DOS_HELPER_INT);
  
    /* check for signature in AX */ 
    if (_AX == 0xaa55) {
    
      return (_BX);
    
  }
  else {
    
      return (0);
    
  }
  
}



char far *
GetListOfLists() 
{
  
  char far *LOL;

  
    
    _AX = DOS_GET_LIST_OF_LISTS;
  
    geninterrupt(0x21);
  
    LOL = MK_FP(_ES, _BX);
  
    return (LOL);
  
}



char far *
GetSDAPointer(void) 
{
  
  char far *SDA;

  
    
    _AX = DOS_GET_SDA_POINTER;
  
    asm {
    
      push ds 
      int 0x21 
     push ds 
     pop es 
     pop ds 
  }
  
   SDA = MK_FP(_ES, _SI);
  
    return (SDA);
  
}



/********************************************
 * InitMFS - call Emulator to initialize MFS
 ********************************************/ 
uint16 InitMFS(void) 
{
  
    uint16 ccode;
  
    char far *LOL;

  
    char far *SDA;

  
    
    LOL = GetListOfLists();
  
    SDA = GetSDAPointer();
  
    
    /* get DOS version into CX */ 
    _CL = _osmajor;
  
    _CH = _osminor;
  
    
    asm {
    
      push ds 
  }
  
    
    _DX = FP_OFF(LOL);
  
    _ES = FP_SEG(LOL);
  
    _SI = FP_OFF(SDA);
  
    _DS = FP_SEG(SDA);
  
    
    _BX = 0x500;
  
    _AX = 0x20;
  
    geninterrupt(DOS_HELPER_INT);
  
    
    asm {
    
      pop ds 
  }
  
}



/********************************************
 * RedirectDevice - redirect a device to a remote resource
 * ON ENTRY:
 *  deviceStr has a string with the device name:
 *    either disk or printer (ex. 'D:' or 'LPT1')
 *  resourceStr has a string with the server and name of resource
 *    (ex. 'TIM\TOOLS')
 *  deviceType indicates the type of device being redirected
 *    3 = printer, 4 = disk
 *  deviceParameter is a value to be saved with this redirection
 *  which will be returned on GetRedirectionList
 * ON EXIT:
 *  returns CC_SUCCESS if the operation was successful,
 *  otherwise returns the DOS error code
 * NOTES:
 *  deviceParameter is used in DOSEMU to return the drive attribute
 *  It is not actually saved and returned as specified by the redirector
 *  specification.  This type of usage is common among commercial redirectors.
 ********************************************/ 
uint16 RedirectDevice(char *deviceStr, char *resourceStr, uint8 deviceType, 
		      uint16 deviceParameter) 
{
  
  char slashedResourceStr[MAX_RESOURCE_PATH_LENGTH];

  
    
    /* prepend the resource string with slashes */ 
    strcpy(slashedResourceStr, "\\\\");
  
    strcat(slashedResourceStr, resourceStr);
  
    
    /* should verify strings before sending them down ??? */ 
    asm {
    
      push ds 
  }
  
    _DS = FP_SEG(deviceStr);
  
    _SI = FP_OFF(deviceStr);
  
    _ES = FP_SEG(slashedResourceStr);
  
    _DI = FP_OFF(slashedResourceStr);
  
    _CX = deviceParameter;
  
    _BL = deviceType;
  
    _AX = DOS_REDIRECT_DEVICE;
  
    geninterrupt(0x21);
  
    asm {
    
      pop ds 
      pushf 
      pop dx 
  }
  
    if (_DX & CARRY_FLAG) {
    
      return (_AX);
    
  }
  else {
    
      return (CC_SUCCESS);
    
  }
  
}



/********************************************
 * GetRedirection - get next entry from list of redirected devices
 * ON ENTRY:
 *  redirIndex has the index of the next device to return
 *    this should start at 0, and be incremented between calls
 *    to retrieve all elements of the redirection list
 * ON EXIT:
 *  returns CC_SUCCESS if the operation was successful, and
 *  deviceStr has a string with the device name:
 *    either disk or printer (ex. 'D:' or 'LPT1')
 *  resourceStr has a string with the server and name of resource
 *    (ex. 'TIM\TOOLS')
 *  deviceType indicates the type of device which was redirected
 *    3 = printer, 4 = disk
 *  deviceParameter has my rights to this resource
 * NOTES:
 *
 ********************************************/ 
uint16 GetRedirection(uint16 redirIndex, char *deviceStr, char *resourceStr, 
		      uint8 * deviceType, uint16 * deviceParameter) 
{
  
    uint16 ccode;
  
    uint8 deviceTypeTemp;
  
    char slashedResourceStr[MAX_RESOURCE_PATH_LENGTH];

  
    
    asm {
    
      push ds 
  }
  
    _DS = FP_SEG(deviceStr);
  
    _SI = FP_OFF(deviceStr);
  
    _ES = FP_SEG(slashedResourceStr);
  
    _DI = FP_OFF(slashedResourceStr);
  
    _BX = redirIndex;
  
    _AX = DOS_GET_REDIRECTION;
  
    asm {
    
      push bp 
      int 21 h 
     pop bp 
     pushf 
     pop dx /* get flags into DX */  
     pop ds 
  }
  
   ccode = _AX;
  
    deviceTypeTemp = _BL;	/* save device type before C ruins it */
  
    *deviceType = deviceTypeTemp;
  
    *deviceParameter = _CX;
  
    
    /* copy back unslashed portion of resource string */ 
    if (_DX & CARRY_FLAG) {
    
      return (ccode);
    
  }
  else {
    
      /* eat the leading slashes */ 
      strcpy(resourceStr, slashedResourceStr + 2);
    
      return (CC_SUCCESS);
    
  }
  
}



/********************************************
 * CancelRedirection - delete a device mapped to a remote resource
 * ON ENTRY:
 *  deviceStr has a string with the device name:
 *    either disk or printer (ex. 'D:' or 'LPT1')
 * ON EXIT:
 *  returns CC_SUCCESS if the operation was successful,
 *  otherwise returns the DOS error code
 * NOTES:
 *
 ********************************************/ 
uint16 CancelRedirection(char *deviceStr) 
{
  
    asm {
    
      push ds 
  }
  
    _DS = FP_SEG(deviceStr);
  
    _SI = FP_OFF(deviceStr);
  
    _AX = DOS_CANCEL_REDIRECTION;
  
    geninterrupt(0x21);
  
    asm {
    
      pop ds 
      pushf 
      pop dx 
  }
  
    if (_DX & CARRY_FLAG) {
    
      return (_AX);
    
  }
  else {
    
      return (CC_SUCCESS);
    
  }
  
}



/*************************************
 * ShowMyRedirections
 *  show my current drive redirections
 * NOTES:
 *  I show the read-only attribute for each drive
 *    which is returned in deviceParam.
 *************************************/ 
void 
ShowMyRedirections(void)
{
  
  
  int driveCount;

  
    uint16 redirIndex, deviceParam, ccode;
  
    uint8 deviceType;
  
    char deviceStr[MAX_DEVICE_STRING_LENGTH];

  
    char resourceStr[MAX_RESOURCE_PATH_LENGTH];

  
    
    redirIndex = 0;
  
    driveCount = 0;
  
    ccode = GetRedirection(redirIndex, deviceStr, resourceStr, 
			   &deviceType, &deviceParam);
  
    while (ccode == CC_SUCCESS) {
    
      /* only print disk redirections here */ 
      if (deviceType == REDIR_DISK_TYPE) {
      
	if (driveCount == 0) {
	
	  printf("Current Drive Redirections:\n");
	
      }
      
	driveCount++;
      
	printf("%-2s = %-20s ", 
	       deviceStr, resourceStr);
      
	/* read attribute is returned in the device parameter */ 
	if (deviceParam & 0x80) {
	
	  printf("attrib = ");
	
	  switch (deviceParam) {
	  
	case READ_ONLY_DRIVE_ATTRIBUTE:
	  
	    printf("READ ONLY");
	  
	    break;
	  
	default:
	  
	    printf("READ/WRITE");
	  
	    break;
	  
	    
	}
	
      }
      
	printf("\n");
      
    }
    
      redirIndex++;
    
      ccode = GetRedirection(redirIndex, deviceStr, resourceStr, 
			     &deviceType, &deviceParam);
    
  }
  
    if (driveCount == 0) {
    
      printf("No drives are currently redirected to Linux.\n");
    
  }
  
}



void 
DeleteDriveRedirection(char *deviceStr) 
{
  
  uint16 ccode;
  
    
    /* convert device string to upper case */ 
    strupr(deviceStr);
  
    ccode = CancelRedirection(deviceStr);
  
    if (ccode) {
    
      printf("Error %x canceling redirection on drive %s\n", 
	     ccode, deviceStr);
    
  }
  else {
    
      printf("Redirection for drive %s was deleted.\n", deviceStr);
    
  }
  
}



main(int argc, char **argv) 
{
  
  uint16 ccode;
  
    uint16 redirIndex, deviceParam;
  
    uint8 deviceType;
  
    
    char deviceStr[MAX_DEVICE_STRING_LENGTH];

  
    char resourceStr[MAX_RESOURCE_PATH_LENGTH];

  
    
    ccode = CheckForDOSEMU();
  
    if (ccode == 0) {
    
      printf("DOSEMU is not running.  This program is intended for use\n");
    
      printf("only with the Linux DOS emulator.\n");
    
      exit(1);
    
  }
  
    
    /* initialize the MFS, just in case the user didn't run EMUFS.SYS */ 
    InitMFS();
  
    
    /* need to parse the command line */ 
    /* if no parameters, then just show current mappings */ 
    if (argc == 1) {
    
      ShowMyRedirections();
    
      exit(0);
    
  }
  
    
    if (strncmpi(argv[1], KEYWORD_DEL, KEYWORD_DEL_COMPARE_LENGTH) == 0) {
    
      DeleteDriveRedirection(argv[2]);
    
      exit(0);
    
  }
  
    
    if (strcmpi(argv[1], "HELP") == 0 || argv[1][0] == '?') {
    
      printf("Usage: LREDIR drive: LINUX\\FS\\path [R]\n");
    
      printf("         redirect a drive to the Linux file system\n");
    
      printf("         if R is specified, the drive will be read-only.\n");
    
      printf("       LREDIR DEL drive:\n");
    
      printf("         delete a drive redirection\n");
    
      printf("       LREDIR\n");
    
      printf("         show current drive redirections\n");
    
      printf("       LREDIR HELP\n");
    
      printf("         show this help screen\n");
    
      exit(0);
    
  }
  
    
    /* assume the command is to redirect a drive */ 
    /* read the drive letter and resource string */ 
    strcpy(deviceStr, argv[1]);
  
    strcpy(resourceStr, argv[2]);
  
    deviceParam = DEFAULT_REDIR_PARAM;
  
    if (argc > 3) {
    
      if (toupper(argv[3][0]) == 'R') {
      
	deviceParam = 1;
      
    }
    
  }
  
    
    /* upper-case both strings */ 
    strupr(deviceStr);
  
    strupr(resourceStr);
  
    
    /* now actually redirect the drive */ 
    ccode = RedirectDevice(deviceStr, resourceStr, REDIR_DISK_TYPE, 
			   deviceParam);
  
    if (ccode) {
    
      printf("Error %x redirecting drive %s to %s\n", 
	     ccode, deviceStr, resourceStr);
    
      goto MainExit;
    
  }
  
    printf("Drive %s redirected to %s\n", deviceStr, resourceStr);
  
    
MainExit:
    return (ccode);
  
}



