Re: Bug#584538: libdebian-installer: problems on Hurd with poll()

[Samuel Thibault <sthibault@debian.org>]

Hello,

Jérémie Koenig, le Fri 04 Jun 2010 14:41:34 +0200, a écrit :
> On Hurd, libdebian-installer gets stuck inside the internal_di_exec()
> function. This is caused by the way poll() reports end-of-file, which
> cannot be portably relied on.
> 
> The attach patch uses feof() instead of POLLHUP to detect it.

> Index: packages/libdebian-installer/src/exec.c
> ===================================================================
> --- packages/libdebian-installer/src/exec.c	(revision 63370)
> +++ packages/libdebian-installer/src/exec.c	(working copy)
> @@ -162,14 +162,12 @@
>        {
>          bool exit = false;
>  
> +        /* Implementations of poll() deliver various combinations of POLLIN and
> +           POLLHUP on EOF. fgets() detects it and we check with feof() below.
> +           References: http://www.greenend.org.uk/rjk/2001/06/poll.html */
>          for (i = 0; i < pipes; i++)
>          {
> -/* References: http://www.greenend.org.uk/rjk/2001/06/poll.html */
> -#if defined(__FreeBSD_kernel__)
> -          if ((pollfds[i].revents & POLLIN) && (! (pollfds[i].revents & POLLHUP)))
> -#else
> -          if (pollfds[i].revents & POLLIN)
> -#endif
> +          if (pollfds[i].revents & (POLLIN | POLLHUP))
>            {
>              while (fgets (line, sizeof (line), files[i].file) != NULL)
>              {
> @@ -180,8 +178,8 @@
>                  len--;
>                }
>                files[i].handler (line, len, io_user_data);
> +              exit = true;
>              }
> -            exit = true;
>            }
>          }
>  
> @@ -189,7 +187,7 @@
>            continue;
>  
>          for (i = 0; i < pipes; i++)
> -          if (pollfds[i].revents & POLLHUP)
> +          if (feof(files[i].file))
>              exit = true;
>  
>          if (exit)

This seems simpler to me.  Could BSD people check they do not have bad
effects?

Samuel