msvcirt: Add a more accurate implementation of streambuf::pbackfail

[Piotr Caban]

On 08/19/15 19:04, Iván Matellanes wrote:
> +/* ?pbackfail at streambuf@@UAEHH at Z */
> +/* ?pbackfail at streambuf@@UEAAHH at Z */
> +DEFINE_THISCALL_WRAPPER(streambuf_pbackfail, 8)
> +#define call_streambuf_pbackfail(this, c) CALL_VTBL_FUNC(this, 36, int, (streambuf*, int), (this, c))
> +int __thiscall streambuf_pbackfail(streambuf *this, int c)
> +{
> +    TRACE("(%p %d)\n", this, c);
> +    if (this->gptr > this->eback)
> +        return *--this->gptr = c;
> +    if (call_streambuf_seekoff(this, -1, SEEKDIR_cur, OPENMODE_in) == EOF)
> +        return EOF;
> +    return c;
> +}
If seekoff is used the buffers needs to be updated. Otherwise next read 
will return incorrect data. You will need to make space for put back 
character and place it in the buffer.

Thanks,
Piotr