3 week bump.
--
Scott Cheloha
> On Jul 28, 2017, at 9:26 PM, Scott Cheloha <scottchel...@gmail.com> wrote:
>
> Hi,
>
> This bit from setvbuf(3):
>
> The size parameter may be given as zero to obtain
> deferred optimal-size buffer allocation as usual.
>
> doesn't describe what's happening in setvbuf.c. When size is 0,
> fp->_fb.base is allocated immediately:
>
> /*
> * Find optimal I/O size for seek optimization. This also returns
> * a `tty flag' to suggest that we check isatty(fd), but we do not
> * care since our caller told us how to buffer.
> */
> flags |= __swhatbuf(fp, &iosize, &ttyflag);
> if (size == 0) {
> buf = NULL; /* force local allocation */
> size = iosize;
> }
>
> /* Allocate buffer if needed. */
> if (buf == NULL) {
>
> if ((buf = malloc(size)) == NULL) {
> /*
> * Unable to honor user's request. We will return
> * failure, but try again with file system size.
> */
> ret = EOF;
> if (size != iosize) {
> size = iosize;
> buf = malloc(size);
> }
>
> }
> if (buf == NULL) {
> /* No luck; switch to unbuffered I/O. */
>
> Allocation is not "deferred," unless I've misunderstood something.
>
> Not sure whether it's important to mention that the allocation
> occurs immediately as opposed to whenever I/O is first attempted,
> so I've just pared the remark down.
>
> --
> Scott Cheloha
>
> Index: lib/libc/stdio/setvbuf.3
> ===================================================================
> RCS file: /cvs/src/lib/libc/stdio/setvbuf.3,v
> retrieving revision 1.4
> diff -u -p -r1.4 setvbuf.3
> --- lib/libc/stdio/setvbuf.3 26 Nov 2014 18:16:32 -0000 1.4
> +++ lib/libc/stdio/setvbuf.3 29 Jul 2017 02:21:49 -0000
> @@ -90,7 +90,7 @@ fully buffered
> The
> .Fa size
> parameter may be given as zero
> -to obtain deferred optimal-size buffer allocation as usual.
> +to obtain an optimal-size buffer allocation.
> If it is not zero, then except for unbuffered files, the
> .Fa buf
> argument should point to a buffer at least
