Re: [Xen-devel] [PATCH] xenconsole: merge pty access check into when it is opened

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 30/11/2013 03:42, Matthew Daley wrote:
> This stops pty_path from being leaked, and removes the toctou race,
> FWIW.
>
> Not sure why it's a separate check to begin with...
>
> Coverity-ID: 1056047
> Signed-off-by: Matthew Daley <mattd@xxxxxxxxxxx>
> ---
>  tools/console/client/main.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/console/client/main.c b/tools/console/client/main.c
> index 38c856a..c32d3eb 100644
> --- a/tools/console/client/main.c
> +++ b/tools/console/client/main.c
> @@ -116,12 +116,12 @@ static int get_pty_fd(struct xs_handle *xs, char *path, 
> int seconds)
>                        * disambiguate: just read the pty path */
>                       pty_path = xs_read(xs, XBT_NULL, path, &len);
>                       if (pty_path != NULL) {
> -                             if (access(pty_path, R_OK|W_OK) != 0)
> -                                     continue;
>                               pty_fd = open(pty_path, O_RDWR | O_NOCTTY);
> -                             if (pty_fd == -1) 
> -                                     err(errno, "Could not open tty `%s'", 
> -                                         pty_path);
> +                             if (pty_fd == -1) {
> +                                     if (errno != EACCES)
> +                                             err(errno, "Could not open tty 
> `%s'",
> +                                                     pty_path);

access() can fail for many more reasons than just EACCES.  I would skip
the errno check entirely and always print the error.

~Andrew

> +                             }
>                               free(pty_path);
>                       }
>               }


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