minix/lib/libc/stdio/ftell.c
2010-08-16 17:07:40 +00:00

45 lines
858 B
C

/*
* ftell.c - obtain the value of the file-position indicator of a stream
*/
/* $Header$ */
#include <assert.h>
#include <stdio.h>
#if (SEEK_CUR != 1) || (SEEK_SET != 0) || (SEEK_END != 2)
#error SEEK_* values are wrong
#endif
#include "loc_incl.h"
#include <sys/types.h>
off_t _lseek(int fildes, off_t offset, int whence);
long ftell(FILE *stream)
{
assert(sizeof(long) == sizeof(off_t));
return (long) ftello(stream);
}
off_t ftello(FILE *stream)
{
long result;
int adjust = 0;
if (io_testflag(stream,_IOREADING))
adjust = -stream->_count;
else if (io_testflag(stream,_IOWRITING)
&& stream->_buf
&& !io_testflag(stream,_IONBF))
adjust = stream->_ptr - stream->_buf;
else adjust = 0;
result = _lseek(fileno(stream), (off_t)0, SEEK_CUR);
if ( result == -1 )
return result;
result += (long) adjust;
return result;
}