[libvirt] [PATCH] systemd: directly notify systemd instead of using sd_notify

[Peter Krempa]

On Mon, Jun 06, 2016 at 15:16:50 +0100, Daniel Berrange wrote:
> The sd_notify method is used to tell systemd when libvirtd
> has finished starting up. All it does is send a datagram
> containing the string parameter to systemd on a UNIX socket
> named in the NOTIFY_SOCKET environment variable. Rather than
> pulling in the systemd libraries for this, just code the
> notification directly in libvirt as this is a stable ABI
> from systemd's POV which explicitly allows independant
> implementations:
> 
> See "Reimplementable Independently" column in the
> "$NOTIFY_SOCKET Daemon Notifications" row:
> 
> https://www.freedesktop.org/wiki/Software/systemd/InterfacePortabilityAndStabilityChart/
> 
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>  configure.ac              |  2 --
>  libvirt.spec.in           | 12 -----------
>  m4/virt-systemd-daemon.m4 | 34 -------------------------------
>  src/Makefile.am           |  4 ++--
>  src/util/virsystemd.c     | 52 ++++++++++++++++++++++++++++++++++++++++++-----
>  5 files changed, 49 insertions(+), 55 deletions(-)
>  delete mode 100644 m4/virt-systemd-daemon.m4

[...]

> diff --git a/src/util/virsystemd.c b/src/util/virsystemd.c
> index 4883f94..71b8f33 100644
> --- a/src/util/virsystemd.c
> +++ b/src/util/virsystemd.c

[...]

> @@ -480,9 +482,49 @@ int virSystemdTerminateMachine(const char *name)
>  void
>  virSystemdNotifyStartup(void)
>  {
> -#ifdef WITH_SYSTEMD_DAEMON
> -    sd_notify(0, "READY=1");
> -#endif
> +#ifdef HAVE_SYS_UN_H
> +    const char *path;
> +    const char *msg = "READY=1";
> +    int fd;
> +    struct sockaddr_un un = {
> +        .sun_family = AF_UNIX,
> +    };
> +    struct iovec iov = {
> +        .iov_base = (char *)msg,
> +        .iov_len = strlen(msg),
> +    };
> +    struct msghdr mh = {
> +        .msg_name = &un,
> +        .msg_namelen = sizeof(un),
> +        .msg_iov = &iov,
> +        .msg_iovlen = 1,
> +    };
> +
> +    if (!(path = virGetEnvBlockSUID("NOTIFY_SOCKET"))) {
> +        VIR_DEBUG("Skipping systemd notify, not requested");
> +        return;
> +    }
> +
> +    if (strlen(path) > sizeof(un.sun_path)) {

Off-by-one by not considering the trailing \0

> +        VIR_WARN("Systemd notify socket path '%s' too long", path);
> +        return;
> +    }

ACK