main: disable nscd properly, if possible

configure.ac

@@ -91,6 +91,7 @@ LT_PREREQ(2.2)
 LT_INIT
 
 AC_SEARCH_LIBS([clock_gettime], [rt], [], [AC_MSG_ERROR([*** POSIX RT library not found])])
+AC_SEARCH_LIBS([dlsym], [dl], [], [AC_MSG_ERROR([*** Dynamic linking loader library not found])])
 AC_SEARCH_LIBS([cap_init], [cap], [], [AC_MSG_ERROR([*** POSIX caps library not found])])
 AC_CHECK_HEADERS([sys/capability.h], [], [AC_MSG_ERROR([*** POSIX caps headers not found])])
 

fixme

@@ -79,8 +79,6 @@
 
 * plymouth different shut down msgs
 
-* fix nscd disable
-
 External:
 
 * sysv functions should color when stdout is tty, not stdin

src/main.c

@@ -994,11 +994,7 @@ int main(int argc, char *argv[]) {
 
                 /* 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."); */
+                nss_disable_nscd();
 
                 if (!serialization) {
                         if (arg_show_status)

src/missing.h

@@ -55,14 +55,6 @@ 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); */
-
 #ifndef AUDIT_SERVICE_START
 #define AUDIT_SERVICE_START     1130    /* Service (daemon) start */
 #endif

src/util.c

@@ -48,6 +48,7 @@
 #include <pwd.h>
 #include <netinet/ip.h>
 #include <linux/kd.h>
+#include <dlfcn.h>
 
 #include "macro.h"
 #include "util.h"
@@ -2979,6 +2980,24 @@ char *ellipsize(const char *s, unsigned length, unsigned percent) {
         return r;
 }
 
+void nss_disable_nscd(void) {
+
+        void (*func)(void);
+
+        /* 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
+         * dlsym() just in case glibc takes this away from us. */
+
+        if ((func = dlsym(RTLD_DEFAULT, "__nss_disable_nscd"))) {
+                log_debug("Disabling nscd.");
+                func();
+        } else
+                log_debug("Cannot disable nscd.");
+}
+
+
 static const char *const ioprio_class_table[] = {
         [IOPRIO_CLASS_NONE] = "none",
         [IOPRIO_CLASS_RT] = "realtime",

src/util.h

@@ -336,6 +336,8 @@ int running_in_chroot(void);
 
 char *ellipsize(const char *s, unsigned length, unsigned percent);
 
+void nss_disable_nscd(void);
+
 const char *ioprio_class_to_string(int i);
 int ioprio_class_from_string(const char *s);