/* fseek( FILE *, long, int )

   This file is part of the Public Domain C Library (PDCLib).
   Permission is granted to use, modify, and / or redistribute at will.
*/

#include <stdio.h>

#ifndef REGTEST

#include "pdclib/_PDCLIB_glue.h"

#ifndef __STDC_NO_THREADS__
#include <threads.h>
#endif

int fseek( struct _PDCLIB_file_t * stream, long offset, int whence )
{
    int rc;
    _PDCLIB_LOCK( stream->mtx );

    if ( stream->status & _PDCLIB_FWRITE )
    {
        if ( _PDCLIB_flushbuffer( stream ) == EOF )
        {
            _PDCLIB_UNLOCK( stream->mtx );
            return EOF;
        }
    }

    stream->status &= ~ _PDCLIB_EOFFLAG;

    if ( stream->status & _PDCLIB_FRW )
    {
        stream->status &= ~ ( _PDCLIB_FREAD | _PDCLIB_FWRITE );
    }

    if ( whence == SEEK_CUR )
    {
        offset -= ( ( (int)stream->bufend - (int)stream->bufidx ) + stream->ungetidx );
    }

    rc = ( _PDCLIB_seek( stream, offset, whence ) != EOF ) ? 0 : EOF;
    _PDCLIB_UNLOCK( stream->mtx );
    return rc;
}

#endif

#ifdef TEST

#include "_PDCLIB_test.h"

#include <string.h>

int main( void )
{
    FILE * fh;
    TESTCASE( ( fh = tmpfile() ) != NULL );
    TESTCASE( fwrite( teststring, 1, strlen( teststring ), fh ) == strlen( teststring ) );
    /* General functionality */
    TESTCASE( fseek( fh, -1, SEEK_END ) == 0  );
    TESTCASE( (size_t)ftell( fh ) == strlen( teststring ) - 1 );
    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
    TESTCASE( (size_t)ftell( fh ) == strlen( teststring ) );
    TESTCASE( fseek( fh, 0, SEEK_SET ) == 0 );
    TESTCASE( ftell( fh ) == 0 );
    TESTCASE( fseek( fh, 5, SEEK_CUR ) == 0 );
    TESTCASE( ftell( fh ) == 5 );
    TESTCASE( fseek( fh, -3, SEEK_CUR ) == 0 );
    TESTCASE( ftell( fh ) == 2 );
    /* Checking behaviour around EOF */
    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
    TESTCASE( ! feof( fh ) );
    TESTCASE( fgetc( fh ) == EOF );
    TESTCASE( feof( fh ) );
    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
    TESTCASE( ! feof( fh ) );
    /* Checking undo of ungetc() */
    TESTCASE( fseek( fh, 0, SEEK_SET ) == 0 );
    TESTCASE( fgetc( fh ) == teststring[0] );
    TESTCASE( fgetc( fh ) == teststring[1] );
    TESTCASE( fgetc( fh ) == teststring[2] );
    TESTCASE( ftell( fh ) == 3 );
    TESTCASE( ungetc( teststring[2], fh ) == teststring[2] );
    TESTCASE( ftell( fh ) == 2 );
    TESTCASE( fgetc( fh ) == teststring[2] );
    TESTCASE( ftell( fh ) == 3 );
    TESTCASE( ungetc( 'x', fh ) == 'x' );
    TESTCASE( ftell( fh ) == 2 );
    TESTCASE( fgetc( fh ) == 'x' );
    TESTCASE( ungetc( 'x', fh ) == 'x' );
    TESTCASE( ftell( fh ) == 2 );
    TESTCASE( fseek( fh, 2, SEEK_SET ) == 0 );
    TESTCASE( fgetc( fh ) == teststring[2] );
    /* Checking error handling */
    TESTCASE( fseek( fh, -5, SEEK_SET ) == -1 );
    TESTCASE( fseek( fh, 0, SEEK_END ) == 0 );
    TESTCASE( fclose( fh ) == 0 );
    return TEST_RESULTS;
}

#endif
