Re: [PATCH 5/8] trans/mtab: do not include non-filesystem translators by default

[Samuel Thibault]

Justus Winter, le Sun 12 Jan 2014 20:08:42 +0100, a écrit :
> Traditionally, /proc/mounts includes only filesystem mount points.
> Previously though, the mtab translator included any kind of
> translator, like all /hurd/storeio translators.  This causes problems
> with umount --all as this would remove the passive translator records
> from nodes in /dev.
> 
> Fix this by only listing filesystem-like translators by default.
> Filesystem-like translators are identified by their response to
> dir_readdir messages sent to their root node.

Ack.

> * trans/mtab.c (all_translators): New variable.
> (options): Add flag to preserve the old behavior.
> (parse_opt): Handle the new flag.
> (is_filesystem_translator): New function.
> (mtab_populate): Skip non-filesystem translators by default.
> ---
>  trans/mtab.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/trans/mtab.c b/trans/mtab.c
> index adfb345..75ef1d3 100644
> --- a/trans/mtab.c
> +++ b/trans/mtab.c
> @@ -40,6 +40,7 @@
>  
>  static char *target_path = NULL;
>  static int insecure = 0;
> +static int all_translators = 0;
>  
>  /* Our control port.  */
>  struct trivfs_control *control;
> @@ -60,6 +61,9 @@ static const struct argp_option options[] =
>  {
>    {"insecure", 'I', 0, 0,
>     "Follow translators not bound to nodes owned by you or root"},
> +  {"all-translators", 'A', 0, 0,
> +   "List all translators, even those that are probably not "
> +   "filesystem translators"},
>    {}
>  };
>  
> @@ -72,6 +76,10 @@ error_t parse_opt (int key, char *arg, struct argp_state 
> *state)
>        insecure = 1;
>        break;
>  
> +    case 'A':
> +      all_translators = 1;
> +      break;
> +
>      case ARGP_KEY_ARG:
>        target_path = realpath (arg, NULL);
>        if (! target_path)
> @@ -277,6 +285,32 @@ mtab_add_entry (struct mtab *mtab, const char *entry, 
> size_t length)
>    return 0;
>  }
>  
> +/* Check whether the given NODE is a directory on a filesystem
> +   translator.  */
> +static boolean_t
> +is_filesystem_translator (file_t node)
> +{
> +  error_t err;
> +  char *data = NULL;
> +  size_t datacnt = 0;
> +  int amount;
> +  err = dir_readdir (node, &data, &datacnt, 0, 1, 0, &amount);
> +  if (data != NULL && datacnt > 0)
> +    vm_deallocate (mach_task_self (), (vm_address_t) data, datacnt);
> +
> +  /* Filesystem translators return either no error, or, if NODE has
> +     not been looked up with O_READ, EBADF to dir_readdir
> +     requests.  */
> +  switch (err)
> +    {
> +    case 0:
> +    case EBADF:
> +      return TRUE;
> +    default:
> +      return FALSE;
> +    }
> +}
> +
>  /* Populates the given MTAB object with the information for PATH.  If
>     INSECURE is given, also follow translators bound to nodes not owned
>     by root or the current user.  */
> @@ -333,6 +367,12 @@ mtab_populate (struct mtab *mtab, const char *path, int 
> insecure)
>        goto errout;
>      }
>  
> +  if (! (all_translators || is_filesystem_translator (node)))
> +    {
> +      err = 0;
> +      goto errout;
> +    }
> +
>    /* Query its options.       */
>    err = file_get_fs_options (node, &argz, &argz_len);
>    if (err)
> -- 
> 1.8.5.2
> 

-- 
Samuel
 > Il [e2fsck] a bien démarré, mais il m'a rendu la main aussitot en me
 > disant "houlala, c'est pas beau à voir votre truc, je préfèrerai que
 > vous teniez vous même la tronçonneuse" (traduction libre)
 NC in Guide du linuxien pervers : "Bien configurer sa tronçonneuse."