Re: [Freedos-devel] [Freedos-user] after find, Error reading from drive A: DOS area: general failure: fixed

[Tom Ehlert]

find bug solved and fixed; contacting the maintainer

TC 2.01 has memory layout

   ff95
   ff
   lfnSupported

now when no LFN are detected,

 LFNFirstFile()
   findfirst(wildcard, &ff, 0);
     findfile(ff, FIND_FIRST, name, attr);
        convDOS(ff)


{  
   memcpy(ff->ff_95.ff_shortname, ff->ff_name, sizeof(ff->ff_name));
   memcpy(ff->ff_95.ff_longname, ff->ff_name, sizeof(ff->ff_name));
   ff->ff_95.ff_attr95 = ff->ff_attr;

the last statement accesses memory behind ff, because ff is
   ffblk ff;

and not ffblk95 ff;

the following source code fixes the bug

**** LFNAPI.C 
***************************************************************************************************************


#include <dir.h>
#include <string.h>
#include <dos.h>

#include "io95\io95.h"
#include "io95\find95.h"
#include "lfnapi.h"

/* MAP files are useful !! */
#define STATIC


STATIC int CheckDriveOnLFN(char drive)
{
    struct REGPACK rp;       /* temporary stack for the registers */
    static char strDrive[4];
    static char filesys[32];

    strcpy(strDrive, "?:\\");
    strDrive[0] = drive;

    rp.r_flags = 1;        /* asure that the carry is set */

    rp.r_ax = 0x71A0;

    rp.r_ds = FP_SEG(strDrive);
    rp.r_dx = FP_OFF(strDrive);

    rp.r_es = FP_SEG(filesys);
    rp.r_di = FP_OFF(filesys);

    rp.r_cx = 32;

    intr(0x21, &rp);

    if (rp.r_flags & 1)
       return 0;

    return (rp.r_bx & 16384) > 0;
}

STATIC int
IsLFNSupported (char *filename)
{
  if (filename && filename[0] && (filename[1] == ':'))
    return CheckDriveOnLFN (filename[0]);
  else
    return CheckDriveOnLFN (getdisk () + 'A');
}

int LFNConvertToSFN(char* file)
{
    static char buffer[67];

    if (IsLFNSupported(file))
    {
        if (lfn2sfn95(file, buffer) == 0)
        {
            strcpy(file, buffer);
            return 1;
        }
        else
            return 0;
    }

    return 1;
}

STATIC int lfnSupported;
STATIC union {
        struct ffblk95 ff95;
        struct ffblk ff;
        } finddata;

int LFNFirstFile(char* wildcard, char* file, char* longfile)
{
    int retVal;

    if (IsLFNSupported(wildcard))
    {  
        lfnSupported = 1;

        retVal = findfirst95(wildcard, &finddata.ff95, 0);

        if (retVal == 0)
        {
            strcpy(file, finddata.ff95.ff_95.ff_shortname);
            strcpy(longfile, finddata.ff95.ff_95.ff_longname);
        }
    
        return retVal;
    }
    else
    {
        lfnSupported = 0;

        retVal = findfirst(wildcard, &finddata.ff, 0);

        if (retVal == 0)
        {
            strcpy(file, finddata.ff.ff_name);
            strcpy(longfile, finddata.ff.ff_name);
        }
    
        return retVal;
    }
}

int LFNNextFile(char* file, char* longfile)
{
    int retVal;

    if (lfnSupported)
    {  
        retVal = findnext95(&finddata.ff95);

        if (retVal == 0)
        {
            strcpy(file, finddata.ff95.ff_95.ff_shortname);
            strcpy(longfile, finddata.ff95.ff_95.ff_longname);
        }
    
        return retVal;
    }
    else
    {
        retVal = findnext(&finddata.ff);

        if (retVal == 0)
        {
            strcpy(file, finddata.ff.ff_name);
            strcpy(longfile, finddata.ff.ff_name);
        }
    
        return retVal;
    }
}

void LFNFindStop()
{
   if (lfnSupported)
   {
        findstop95(&finddata.ff95);
   }
}

***********************************************************************

Tom


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