[PATCH 5/8] mdev: add syslog logging mode

[Denys Vlasenko]

Applied, thanks

On Mon, Dec 16, 2019 at 10:57 PM Jan Klötzke <jan at kloetzke.net> wrote:
>
> If mdev is run as daemon it should be possible to forward the debug
> messages to syslog. This feature might be useful if mdev is run with -s
> during boot too. OTOH it makes no sense for the daemon to log to
> mdev.log. This can be handled by a syslog daemon way better. If the
> daemon stays in the foreground due to -f, the messages are still written
> to stderr as before.
>
> Signed-off-by: Jan Klötzke <jan at kloetzke.net>
> ---
>  util-linux/mdev.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/util-linux/mdev.c b/util-linux/mdev.c
> index 91c4ff466..1ef7a029e 100644
> --- a/util-linux/mdev.c
> +++ b/util-linux/mdev.c
> @@ -81,7 +81,7 @@
>  //kbuild:lib-$(CONFIG_MDEV) += mdev.o
>
>  //usage:#define mdev_trivial_usage
> -//usage:       "[-s]" IF_FEATURE_MDEV_DAEMON(" | [-df]")
> +//usage:       "[-S] " IF_FEATURE_MDEV_DAEMON("[") "[-s]" IF_FEATURE_MDEV_DAEMON(" | [-df]]")
>  //usage:#define mdev_full_usage "\n\n"
>  //usage:       "mdev -s is to be run during boot to scan /sys and populate /dev.\n"
>  //usage:       IF_FEATURE_MDEV_DAEMON(
> @@ -89,6 +89,9 @@
>  //usage:       "       -f: stay in foreground.\n"
>  //usage:       )
>  //usage:       "\n"
> +//usage:       "optional arguments:\n"
> +//usage:       "       -S: Log to syslog too\n"
> +//usage:       "\n"
>  //usage:       "Bare mdev is a kernel hotplug helper. To activate it:\n"
>  //usage:       "       echo /sbin/mdev >/proc/sys/kernel/hotplug\n"
>  //usage:       IF_FEATURE_MDEV_CONF(
> @@ -114,6 +117,7 @@
>  #include "common_bufsiz.h"
>  #include "xregex.h"
>  #include <linux/netlink.h>
> +#include <syslog.h>
>
>  /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
>   * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
> @@ -1244,8 +1248,9 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
>  {
>         enum {
>                 MDEV_OPT_SCAN       = 1 << 0,
> -               MDEV_OPT_DAEMON     = 1 << 1,
> -               MDEV_OPT_FOREGROUND = 1 << 2,
> +               MDEV_OPT_SYSLOG     = 1 << 1,
> +               MDEV_OPT_DAEMON     = 1 << 2,
> +               MDEV_OPT_FOREGROUND = 1 << 3,
>         };
>         int opt;
>         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
> @@ -1261,7 +1266,7 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
>
>         xchdir("/dev");
>
> -       opt = getopt32(argv, "s" IF_FEATURE_MDEV_DAEMON("df"));
> +       opt = getopt32(argv, "sS" IF_FEATURE_MDEV_DAEMON("df"));
>
>  #if ENABLE_FEATURE_MDEV_CONF
>         G.filename = "/etc/mdev.conf";
> @@ -1271,8 +1276,17 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
>         }
>  #endif
>
> +       if (opt & MDEV_OPT_SYSLOG) {
> +               openlog(applet_name, LOG_PID, LOG_DAEMON);
> +               logmode |= LOGMODE_SYSLOG;
> +       }
> +
>  #if ENABLE_FEATURE_MDEV_DAEMON
>         if (opt & MDEV_OPT_DAEMON) {
> +               // there is no point in write()ing to /dev/null
> +               if (!(opt & MDEV_OPT_FOREGROUND))
> +                       logmode &= ~LOGMODE_STDIO;
> +
>                 /*
>                  * Daemon mode listening on uevent netlink socket. Fork away
>                  * after initial scan so that caller can be sure everything
> @@ -1283,8 +1297,6 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
>                 if (!(opt & MDEV_OPT_FOREGROUND))
>                         bb_daemonize_or_rexec(0, argv);
>
> -               open_mdev_log(NULL, getpid());
> -
>                 daemon_loop(temp, fd);
>         }
>  #endif
> --
> 2.20.1
>
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