Re: [patch] libstdc++/67747 Allocate space for dirent::d_name

[Martin Sebor <msebor at gmail dot com>]

On 10/02/2015 11:43 AM, Florian Weimer wrote:
> On 10/02/2015 07:37 PM, Martin Sebor wrote:
>
> > I'm not sure what you are basing this assertion on. In the man
> > pages I have looked at, memcpy is documented as MT-Safe. readdir
> > is documented as MT-Unsafe. The Unsafe definition is clear:
> > contains global and static data that is not protected.
>
> I think the Solaris thread-safety attributes are a bit too simplistic to
> capture the whole scope of thread safety issues for functions operating
> on mutable data.
>
> > For example, Solaris 11.2:
> > http://docs.oracle.com/cd/E36784_01/html/E36874/readdir-3c.html
>
> “It is safe to use readdir() in a threaded application, so long as only
> one thread reads from the directory stream at any given time. The
> readdir() function is generally preferred over the readdir_r() function.”

Ah, I see the discrepancy. I had a few pages open, one for Solaris
9 and one for 11.2. The newer one has the quote, the older one does
not.

Here's the older page:
http://docs.oracle.com/cd/E19683-01/816-0213/6m6ne3895/index.html

With that, I agree that using readdir is thread-safe on Solaris 11.2.
It is not safe on Solaris 9, and it would not be safe on other systems
that don't document it as such.

Martin