Re: [PATCH v2 2/5] virtiofsd: create lock/pid file in per user cache dir

[Dr. David Alan Gilbert]

* Vivek Goyal (vgoyal@redhat.com) wrote:
> Right now we create lock/pid file in /usr/local/var/... and unprivliged
> user does not have access to create files there.

I *think* the /usr/local there is coming from the build config of your
qemu; but I'm not 100% sure whether it's just it's --preifx

> Hence, in unprivileged mode, create this file in per user cache dir
> as specified by environment variable XDG_RUNTIME_DIR.

Yes; it's interesting that qemu daemons are somewhat inconsistent in
this; most of them ask for a --pidfile to say where you want it;
but not all.

> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
>  tools/virtiofsd/fuse_virtio.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
> index 6b21a93841..1551a94757 100644
> --- a/tools/virtiofsd/fuse_virtio.c
> +++ b/tools/virtiofsd/fuse_virtio.c
> @@ -972,8 +972,21 @@ static bool fv_socket_lock(struct fuse_session *se)
>      g_autofree gchar *pidfile = NULL;
>      g_autofree gchar *dir = NULL;
>      Error *local_err = NULL;
> +    gboolean unprivileged = false;
>  
> -    dir = qemu_get_local_state_pathname("run/virtiofsd");
> +    if (geteuid() != 0)
> +        unprivileged = true;

Note qemu style guides need {'s on that.

> +    /*
> +     * Unpriviliged users don't have access to /usr/local/var. Hence
> +     * store lock/pid file in per user cache directory. Use environment
> +     * variable XDG_RUNTIME_DIR.
> +     */
> +    if (unprivileged) {
> +        dir = g_strdup_printf("%s/virtiofsd", g_get_user_runtime_dir());
> +    } else {
> +        dir = qemu_get_local_state_pathname("run/virtiofsd");
> +    }

Yeh that's OK, so with the  { fixed;

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

A few other possible thoughts:
  a) Just always use g_get_runtime_dir as the top; even for root - it
seems to come out as /root/.cache for root, which isn't terrible.
  b) Maybe put this code in qemu_get_local_state_pathname?

Dave


>  
>      if (g_mkdir_with_parents(dir, S_IRWXU) < 0) {
>          fuse_log(FUSE_LOG_ERR, "%s: Failed to create directory %s: %s",
> -- 
> 2.25.4
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK