Encapsulating the DOS IOCTL Interface

Listing 3 iohandle.h — base class for handle-based IOCTL for character devices and files

#ifndef __IOHANDLE_H
#define __IOHANDLE_H
#include "iobase.h"

class IoctlHandle : public IoctlBase {
protected:
   unsigned handle_info( int );      //get info
   virtual void IoctlError(int);
   IoctlHandle( int handle );      //constructor 1
   IoctlHandle( const char *path );  //constructor 2
   int _handle;        //validated handle
   int _pathused;   //!0 if Init( char *) called
   unsigned _info;     //handle info word
public:
   static IoctlHandle *Init( int handle );
   static IoctlHandle *Init(const char *);
   ~IoctlHandle();     //destructor

   //Format of handle information word ....
   enum file_info   {
   drive_number = 0x003f, //bits 0-5 =drive#

                      //(0-based, A=0)
                  //= drive containing the file.
   cleared = 0x0040,  //bit 6=1 if file cleared
                   // (i.e. not written to)
   file_bit = 0x0080,    //bit 7=0 if a file
   fixed = 0x0800,   //bit 11=1, media not removable
   noInherit = 0x1000,  //bit 12=1, no inherit (?)
   noCommit = 0x4000,  //bit 14=1, Date/time not set
                    //on handle close operation
   remote = 0x8000     //bit 15=1 if file remote
   };
   enum device_info {
   std_in = 0x0001,    //bit 0=1 if std input
   std_out = 0x0002,   //bit 1=1 if std output
   std_nul = 0x0004,   //bit 2=1 if NUL device
   std_clk = 0x0008,   //bit 3=1 if CLOCK device
   use_int29h = 0x0010,  //use int 29h for single
                     //char text output.....
   binary = 0x0020,      //bit 5=0 if ASCII,
                     // =1 if binary
   eof = 0x0040,       //bit 6=0 if at EOF on input
   device_bit = 0x0080,   //bit 7=1 if a device
   network = 0x1000,  //bit 12=1 if network device
   ioctl = 0x4000  //bit 14=1 if driver can
                //process IOCTL strings via
                //subfunctions 02h & 03h
   };
   int readHandle(void) { return _handle; }
   int isFile( void )
      {  return !(file_bit & info); }
   int isDevice( void )
      {  return device_bit & _info; }
   unsigned handleInfo(void) //get & refresh _info
      {   _info = handle_info( _handle );
          return _info;       }
   int inputStatus( void );  //!0=ready, 0=not
   int outputStatus( void ); //!0=ready, 0=not
   int isRemote(void);  //File/device handle remote?
};  //.... end class IoctlHandle
#endif //_IOHANDLE_H

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