flask-jamlib/jamlib/lastread.c

/*
    JAMLIB - A JAM subroutine library
    Copyright (C) 1999 Björn Stenberg

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Changes made by Johan Billing 2000-04-16:
	 
    - Changed source to use feof() instead of errno == EPASTEOF
    - Changed source to use structrw to read and write structures
*/	 

/***********************************************************************
**
**  LASTREAD.C -- Lastread pointer handling
**
**  Author: Bj”rn Stenberg (bjorn.stenberg@sth.frontec.se)
**
***********************************************************************/
#include <stdio.h>
#include <errno.h>

#include "jam.h"
#include "structrw.h"

/***********************************************************************
**
**  File global variables
**
***********************************************************************/

/***********************************************************************
**
**  JAM_ReadLastRead - Read LastRead record
**
***********************************************************************/
int JAM_ReadLastRead( s_JamBase*	Base_PS,
		      uint32_t 		User_I,
		      s_JamLastRead* 	Record_PS )
{
    s_JamLastRead Record_S;
    int Pos_I;

    if (!Record_PS)
	return JAM_BAD_PARAM;

    if ( fseek( Base_PS->LrdFile_PS, 0, SEEK_SET ) ) {
	Base_PS->Errno_I = errno;
	return JAM_IO_ERROR;
    }

    for ( Pos_I = 0; ; Pos_I++ ) {

   if ( 1 > freadjamlastread(Base_PS->LrdFile_PS,&Record_S) ) {
            if ( feof(Base_PS->LrdFile_PS) )
		return JAM_NO_USER;
	    Base_PS->Errno_I = errno;
	    return JAM_IO_ERROR;
	}

	if ( Record_S.UserID == User_I ) {
	    Base_PS->LastUserPos_I  = Pos_I;
	    Base_PS->LastUserId_I = User_I;
	    *Record_PS = Record_S;
	    return 0;
	}
    }

    return 0;
}

/***********************************************************************
**
**  JAM_WriteLastRead - Write LastRead record
**
***********************************************************************/
int JAM_WriteLastRead( s_JamBase* 	Base_PS,
		       uint32_t 		User_I,
		       s_JamLastRead* 	Record_PS )
{
    s_JamLastRead Record_S;
    int Pos_I;

    if (!Record_PS)
	return JAM_BAD_PARAM;

    /* if the last read is stored */
    if ( User_I == Base_PS->LastUserId_I ) {
	Pos_I = Base_PS->LastUserPos_I * sizeof( s_JamLastRead );

	if ( fseek( Base_PS->LrdFile_PS, Pos_I, SEEK_SET ) ) {
	    Base_PS->Errno_I = errno;
	    return JAM_IO_ERROR;
	}

	/* be safe, check it */
	if ( 1 > freadjamlastread(Base_PS->LrdFile_PS,&Record_S) ) {
	    Base_PS->Errno_I = errno;
	    return JAM_IO_ERROR;
	}

	/* is it where we expected it to be? */
	if ( User_I == Record_S.UserID ) {
	    
	    if ( fseek( Base_PS->LrdFile_PS, Pos_I, SEEK_SET ) ) {
		Base_PS->Errno_I = errno;
		return JAM_IO_ERROR;
	    }

	if ( 1 > fwritejamlastread(Base_PS->LrdFile_PS,Record_PS) ) {
		Base_PS->Errno_I = errno;
		return JAM_IO_ERROR;
	    }

            fflush(Base_PS -> LrdFile_PS);

	    return 0;
	}
    }

    /* no last position, or position incorrect */
    if ( fseek( Base_PS->LrdFile_PS, 0, SEEK_SET ) ) {
	Base_PS->Errno_I = errno;
	return JAM_IO_ERROR;
    }

    for ( Pos_I = 0; ; Pos_I++ ) {

        if ( 1 > freadjamlastread(Base_PS->LrdFile_PS,&Record_S) ) {
            if ( feof(Base_PS->LrdFile_PS) ) {

		/* user not in file, append a new record  */
		if ( fseek( Base_PS->LrdFile_PS, 0, SEEK_END ) ) {
		    Base_PS->Errno_I = errno;
		    return JAM_IO_ERROR;
		}
		break;
	    }
	    Base_PS->Errno_I = errno;
	    return JAM_IO_ERROR;
	}

	/* found the user? */
	if ( Record_S.UserID == User_I ) {
	    if ( fseek( Base_PS->LrdFile_PS, Pos_I * sizeof(s_JamLastRead),
		        SEEK_SET ) ) {
		Base_PS->Errno_I = errno;
		return JAM_IO_ERROR;
	    }
	    break;
	}
    }

    if ( 1 > fwritejamlastread(Base_PS->LrdFile_PS,Record_PS) ) {
	Base_PS->Errno_I = errno;
	return JAM_IO_ERROR;
    }

    fflush( Base_PS->LrdFile_PS );

    return 0;
}