add ENABLE_FEATURE_SYSTEMD and use it in syslogd

Signed-off-by: Davide Cavalca <davide@geexbox.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 73 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 968bdcf5a..32e25a8d4 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1217,6 +1217,12 @@ extern void selinux_preserve_fcontext(int fdesc) FAST_FUNC;
 #endif
 extern void selinux_or_die(void) FAST_FUNC;
 
+
+/* systemd support */
+#define SD_LISTEN_FDS_START 3
+int sd_listen_fds(void);
+
+
 /* setup_environment:
  * if chdir pw->pw_dir: ok: else if to_tmp == 1: goto /tmp else: goto / or die
  * if clear_env = 1: cd(pw->pw_dir), clear environment, then set
diff --git a/libbb/systemd_support.c b/libbb/systemd_support.c
new file mode 100644
index 000000000..981296dbb
--- /dev/null
+++ b/libbb/systemd_support.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2011 Davide Cavalca <davide@geexbox.org>
+ *
+ * Based on http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.c
+ * Copyright 2010 Lennart Poettering
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "libbb.h"
+
+//config:config FEATURE_SYSTEMD
+//config:       bool "Enable systemd support"
+//config:       default y
+//config:       help
+//config:         If you plan to use busybox daemons on a system where daemons
+//config:         are controlled by systemd, enable this option.
+//config:         If you don't use systemd, it is still safe to enable it,
+//config:         but yhe downside is increased code size.
+
+//kbuild:lib-$(CONFIG_FEATURE_SYSTEMD) += systemd_support.o
+
+int sd_listen_fds(void)
+{
+        const char *e;
+        int n;
+        int fd;
+
+        e = getenv("LISTEN_PID");
+        if (!e)
+                return 0;
+        n = xatoi_positive(e);
+        /* Is this for us? */
+        if (getpid() != (pid_t) n)
+                return 0;
+
+        e = getenv("LISTEN_FDS");
+        if (!e)
+                return 0;
+        n = xatoi_positive(e);
+        for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++)
+                close_on_exec_on(fd);
+
+        return n;
+}
diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index fb7309538..24cab3b6c 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -512,6 +512,11 @@ static NOINLINE int create_socket(void)
         int sock_fd;
         char *dev_log_name;
 
+#if ENABLE_FEATURE_SYSTEMD
+        if (sd_listen_fds() == 1)
+                return SD_LISTEN_FDS_START;
+#endif
+
         memset(&sunx, 0, sizeof(sunx));
         sunx.sun_family = AF_UNIX;