AmigActive 26/AACD 26.iso/AACD/Programming/ace_gpl_release/src/lib/c/rfiles.c

C/C++ Source or Header | 1998-10-04 | 4.7 KB | 214 lines

/*
** Random file library functions for ACE.
** Copyright (C) 1998 David Benn
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public License
** as published by the Free Software Foundation; either version 2
** of the License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
**
** Note: According to the 2.04 (KS 37.175) dos.library autodocs,
**      Seek() doesn't return -1 for V36 or V37, and IoErr()
**     must be called. However, under pre-2.x/3.x systems (according
**     to the 2nd edition Bantam AmigaDOS reference), under 2.04
**     (by testing), and under 3.0 (by testing), Seek() _does_
**     return -1 upon failure. That's good enough for me. Accordingly,
**     ACE's error_code value is set to the dos/dos.h ERROR_SEEK_ERROR
**     value when Seek() returns -1. Why not just call IoErr() you ask?
**     Because the value IoErr() returns after Seek() returns -1 were
**     found to be different under 2.04 and 3.0! Geez! What the heck are
**     these guys trying to do to me!? And I think _my_ code is inconsistent
**     sometimes!
**
** Author: David J Benn
**   Date: 9th-11th March 1996
*/

#include <exec/types.h>
#include <libraries/dos.h>

#define ERR             -1L
#define MAXFILE            255L
#define BAD_FILE_NUMBER        52L    /* see also ACE:lib/asm/file.s [BFN] */
#define    BAD_RECORD_NUMBER    63L
#define NEXT            0L

/*
** External variables.
*/
extern    LONG error_code;
extern    file_handle_list[255];

/*
** Function definitions.
*/
void GetRecord(recordNum, bytes, buffer, fileNum)
LONG recordNum;
LONG bytes;
void *buffer;
LONG fileNum;
{
/*
** Get the specified record (1..N) from
** the specified file (1..255), placing
** it into the supplied buffer.
*/
BPTR fh;
LONG result;

    if (fileNum < 1 || fileNum > 255)
    {
        error_code = BAD_FILE_NUMBER;
        return;
    }
    else
    if (recordNum < 1 && recordNum != NEXT)
    {
        error_code = BAD_RECORD_NUMBER;
        return;
    }
    else
    {
        fh = file_handle_list[fileNum-1];
        if (fh == NULL)
        {
            error_code = BAD_FILE_NUMBER;
            return;
        }

        /*
        ** Position the file pointer at the correct location?
        */
        if (recordNum != NEXT)
        {
            /*
            ** Position the file pointer so we're ready to read.
            */
            result = Seek(fh,bytes*(recordNum-1),OFFSET_BEGINNING);
            if (result == ERR)
            {
                error_code = ERROR_SEEK_ERROR;
                return;
            }
        }

        result = Read(fh,buffer,bytes);
        if (result != bytes) error_code = IoErr();
    }
}

void PutRecord(recordNum, bytes, buffer, fileNum)
LONG recordNum;
LONG bytes;
void *buffer;
LONG fileNum;
{
/*
** Store the specified record (1..N) in the
** specified file (1..255), taking it from
** the supplied buffer. If the file is
** not large enough to accomodate the
** new record, make it so.
*/
BPTR fh;
LONG result;

    if (fileNum < 1 || fileNum > 255)
    {
        error_code = BAD_FILE_NUMBER;
        return;
    }
    else
    if (recordNum < 1 && recordNum != NEXT)
    {
        error_code = BAD_RECORD_NUMBER;
        return;
    }
    else
    {
        fh = file_handle_list[fileNum-1];
        if (fh == NULL)
        {
            error_code = BAD_FILE_NUMBER;
            return;
        }

        /*
        ** Position the file pointer at the correct location?
        */
        if (recordNum != NEXT)
        {
            /*
            ** Position the file pointer so we're ready to write.
            */
            result = Seek(fh,bytes*(recordNum-1),OFFSET_BEGINNING);
            if (result == ERR)
            {
                /*
                ** Assume seek failed because the file
                ** was too small. Attempt to increase
                ** the file's size (V36+ only, ie. not Wb 1.3).
                */
                if (system_version() < 36)
                {
                    error_code = ERROR_SEEK_ERROR;
                    return;
                }
                else
                {
                    /*
                    ** Set file pointer and therefore new end-of-file
                    ** to the _start_ of the record we want to write.
                    */
                    result = SetFileSize(fh, bytes*(recordNum-1), OFFSET_BEGINNING);
                    if (result == ERR)
                    {
                        error_code = ERROR_SEEK_ERROR;
                        return;
                    }
                }
            }
        }

        result = Write(fh,buffer,bytes);
        if (result != bytes) error_code = IoErr();
    }
}

LONG FilePosition(fileNum)
LONG fileNum;
{
/*
** Return the current position of the file
** pointer for the specified file, ie. the
** number of bytes read or written.
*/
BPTR fh;

    if (fileNum < 1 || fileNum > 255)
    {
        error_code = BAD_FILE_NUMBER;
        return;
    }
    else
    {
        fh = file_handle_list[fileNum-1];
        if (fh == NULL)
        {
            error_code = BAD_FILE_NUMBER;
            return;
        }

        return Seek(fh,0L,OFFSET_CURRENT);
    }
}