On Tue, Mar 28, 2017 at 11:15:12PM +0200, Christian Couder wrote:
> On Sun, Mar 26, 2017 at 3:43 PM, René Scharfe <l.s.r@xxxxxx> wrote:
> > FreeBSD implements getcwd(3) as a syscall, but falls back to a version
> > based on readdir(3) if it fails for some reason. The latter requires
> > permissions to read and execute path components, while the former does
> > not. That means that if our buffer is too small and we're missing
> > rights we could get EACCES, but we may succeed with a bigger buffer.
> >
> > Keep retrying if getcwd(3) indicates lack of permissions until our
> > buffer can fit PATH_MAX bytes, as that's the maximum supported by the
> > syscall on FreeBSD anyway. This way we do what we can to be able to
> > benefit from the syscall, but we also won't loop forever if there is a
> > real permission issue.
>
> Sorry to be late and maybe I missed something obvious, but the above
> and the patch seem complex to me compared with something like:
>
> diff --git a/strbuf.c b/strbuf.c
> index ace58e7367..25eadcbedc 100644
> --- a/strbuf.c
> +++ b/strbuf.c
> @@ -441,7 +441,7 @@ int strbuf_readlink(struct strbuf *sb, const char
> *path, size_t hint)
> int strbuf_getcwd(struct strbuf *sb)
> {
> size_t oldalloc = sb->alloc;
> - size_t guessed_len = 128;
> + size_t guessed_len = PATH_MAX > 128 ? PATH_MAX : 128;
>
> for (;; guessed_len *= 2) {
> strbuf_grow(sb, guessed_len);
I think the main reason is just that we do not have to pay the price to
allocate PATH_MAX-sized buffers when they are rarely used.
I doubt it matters all that much in practice, though.
-Peff