#include "syscalls.h"

/* _fillbuf:  allocate and fill input buffer */
int _fillbuf(FILE *fp)
{
    int bufsize;

    if ((fp->flag&(_READ|_EOF|_ERR)) != _READ)
        return EOF;
    bufsize = (fp->flag & _UNBUF) ? 1 : BUFSIZ;
    if (fp->base == NULL)     /* no buffer yet */
        if ((fp->base = (char *) malloc(bufsize)) == NULL)
            return EOF;       /* can't get buffer */
    fp->ptr = fp->base;
    fp->cnt = read(fp->fd, fp->ptr, bufsize);
    if (--fp->cnt < 0) {
        if (fp->cnt == -1)
            fp->flag |= _EOF;
        else
            fp->flag |= _ERR;
        fp->cnt = 0;
        return EOF;
    }
    return (unsigned char) *fp->ptr++;
}