main: disable nscd if we can to avoid deadlock, just in case

fixme

@@ -53,8 +53,6 @@
 
 * systemd-install disable should recursively kill all symlinks
 
-* __nss_disable_nscd() aufrufen um loops zu verhindern
-
 * in %post create all symlinks manually and use inittab data
 
 * check mtimes of dirs and unit files in systemctl

src/macro.h

@@ -40,6 +40,7 @@
 #define _unlikely_(x) (__builtin_expect(!!(x),0))
 #define _public_ __attribute__ ((visibility("default")))
 #define _hidden_ __attribute__ ((visibility("hidden")))
+#define _weakref_(x) __attribute__((weakref(#x)))
 
 /* Rounds up */
 static inline size_t ALIGN(size_t l) {

src/main.c

@@ -44,6 +44,7 @@
 #include "special.h"
 #include "conf-parser.h"
 #include "bus-errors.h"
+#include "missing.h"
 
 static enum {
         ACTION_RUN,
@@ -935,13 +936,24 @@ int main(int argc, char *argv[]) {
 
         log_info(PACKAGE_STRING " running in %s mode.", manager_running_as_to_string(arg_running_as));
 
-        if (arg_running_as == MANAGER_SYSTEM && !serialization) {
-                if (arg_show_status)
-                        status_welcome();
-                modprobe_setup(arg_nomodules);
-                kmod_setup();
-                hostname_setup();
-                loopback_setup();
+        if (arg_running_as == MANAGER_SYSTEM) {
+
+                /* Disable nscd, to avoid deadlocks when systemd uses
+                 * NSS and the nscd socket is maintained by us. */
+                if (nss_disable_nscd) {
+                        log_debug("Disabling nscd");
+                        nss_disable_nscd();
+                } else
+                        log_debug("Hmm, can't disable nscd.");
+
+                if (!serialization) {
+                        if (arg_show_status)
+                                status_welcome();
+                        modprobe_setup(arg_nomodules);
+                        kmod_setup();
+                        hostname_setup();
+                        loopback_setup();
+                }
         }
 
         if ((r = manager_new(arg_running_as, &m)) < 0) {

src/missing.h

@@ -29,6 +29,8 @@
 #include <fcntl.h>
 #include <unistd.h>
 
+#include "macro.h"
+
 #ifndef RLIMIT_RTTIME
 #define RLIMIT_RTTIME 15
 #endif
@@ -53,4 +55,12 @@ static inline int pivot_root(const char *new_root, const char *put_old) {
         return syscall(SYS_pivot_root, new_root, put_old);
 }
 
+/* This is an internal glibc function call. We are not supposed to
+ * call this, because we are not nscd. However sometimes we feel
+ * really dangerous and do it nonetheless. Muahahah! But at least we
+ * protect this with a weak ref just in case glibc takes this away
+ * from us. */
+
+static void nss_disable_nscd(void) _weakref_(__nss_disable_nscd);
+
 #endif