On Sat, Dec 15, 2018 at 09:15:14PM -0700, Todd C. Miller wrote:
> On Fri, 14 Dec 2018 10:49:23 -0700, "Todd C. Miller" wrote:
>
> > After thinking about this a bit more I believe it best to just use
> > the existing FILE * and swap in the buffer temporarily. There's
> > no need to store the value of the old buffer; since we are unbuffered
> > it can only point to _nbuf.
>
> The last diff had a bug. It turns out that __srefill() assumes it
> has the entire buffer to use so we need to reset the buffer each
> time we call it.
Sorry to have missed it while I reviewed the previous diff. Adjusting
the buffer pointer/size at each time is the right thing to do.
ok semarie@
> This fixes the problem naddy@ saw with a few of the ports in python
> code.
>
> - todd
>
> Index: lib/libc/stdio/fread.c
> ===================================================================
> RCS file: /cvs/src/lib/libc/stdio/fread.c,v
> retrieving revision 1.18
> diff -u -p -u -r1.18 fread.c
> --- lib/libc/stdio/fread.c 16 Dec 2018 03:40:40 -0000 1.18
> +++ lib/libc/stdio/fread.c 16 Dec 2018 04:12:32 -0000
> @@ -68,6 +68,36 @@ fread(void *buf, size_t size, size_t cou
> fp->_r = 0;
> total = resid;
> p = buf;
> +
> + /*
> + * If we're unbuffered we know that the buffer in fp is empty so
> + * we can read directly into buf. This is much faster than a
> + * series of one byte reads into fp->_nbuf.
> + */
> + if ((fp->_flags & __SNBF) != 0 && buf != NULL) {
> + while (resid > 0) {
> + /* set up the buffer */
> + fp->_bf._base = fp->_p = p;
> + fp->_bf._size = resid;
> +
> + if (__srefill(fp)) {
> + /* no more input: return partial result */
> + count = (total - resid) / size;
> + break;
> + }
> + p += fp->_r;
> + resid -= fp->_r;
> + }
> +
> + /* restore the old buffer (see __smakebuf) */
> + fp->_bf._base = fp->_p = fp->_nbuf;
> + fp->_bf._size = 1;
> + fp->_r = 0;
> +
> + FUNLOCKFILE(fp);
> + return (count);
> + }
> +
> while (resid > (r = fp->_r)) {
> (void)memcpy(p, fp->_p, r);
> fp->_p += r;
--
Sebastien Marie
