#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include "fileutil.h"

int fflush(FILE *fp)
{
	// TODO: fflush(NULL) should flush "all" files (do we track them?)
	if(!fp) {
		errno = EINVAL;
		return EOF;
	}
	if(!fp->buf)
		return 0;

	/* In reading mode, reset the file offset */
	if(fp->bufdir == __FILE_BUF_READ && fp->bufpos < fp->bufread) {
		fp->fdpos = fp->fdpos - fp->bufread + fp->bufpos;
		lseek(fp->fd, fp->fdpos, SEEK_SET);
		fp->bufpos = 0;
		fp->bufread = 0;
		return 0;
	}

	/* In writing mode, write pending data */
	if(fp->bufdir == __FILE_BUF_WRITE && fp->bufpos > 0) {
		ssize_t written = __fp_write(fp, fp->buf, fp->bufpos);
		fp->bufpos = 0;
		return (written == (ssize_t)fp->bufpos ? 0 : EOF);
	}

	return 0;
}