Introduce CONF_DIRS_NULSTR helper to define standard conf dirs

Several different systemd tools define a nulstr containing a standard
series of configuration file directories, in /etc, /run, /usr/local/lib,
/usr/lib, and (#ifdef HAVE_SPLIT_USR) /lib.  Factor that logic out into
a new helper macro, CONF_DIRS_NULSTR.

6 files changed, 20 insertions, 45 deletions

diff --git a/src/binfmt/binfmt.c b/src/binfmt/binfmt.c
index c1c152239b..0a15fafc60 100644
--- a/src/binfmt/binfmt.c
+++ b/src/binfmt/binfmt.c
@@ -36,15 +36,7 @@
 #include "fileio.h"
 #include "build.h"
 
-static const char conf_file_dirs[] =
-        "/etc/binfmt.d\0"
-        "/run/binfmt.d\0"
-        "/usr/local/lib/binfmt.d\0"
-        "/usr/lib/binfmt.d\0"
-#ifdef HAVE_SPLIT_USR
-        "/lib/binfmt.d\0"
-#endif
-        ;
+static const char conf_file_dirs[] = CONF_DIRS_NULSTR("binfmt");
 
 static int delete_rule(const char *rule) {
         _cleanup_free_ char *x = NULL, *fn = NULL;
diff --git a/src/modules-load/modules-load.c b/src/modules-load/modules-load.c
index 08de5e0ce9..c676fd1c18 100644
--- a/src/modules-load/modules-load.c
+++ b/src/modules-load/modules-load.c
@@ -38,15 +38,7 @@
 
 static char **arg_proc_cmdline_modules = NULL;
 
-static const char conf_file_dirs[] =
-        "/etc/modules-load.d\0"
-        "/run/modules-load.d\0"
-        "/usr/local/lib/modules-load.d\0"
-        "/usr/lib/modules-load.d\0"
-#ifdef HAVE_SPLIT_USR
-        "/lib/modules-load.d\0"
-#endif
-        ;
+static const char conf_file_dirs[] = CONF_DIRS_NULSTR("modules-load");
 
 static void systemd_kmod_log(void *data, int priority, const char *file, int line,
                              const char *fn, const char *format, va_list args) {
diff --git a/src/shared/macro.h b/src/shared/macro.h
index 9ee332c8df..6d4712c30d 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -384,6 +384,21 @@ do {                                                                    \
                 _found;                                                 \
         })
 
+/* Return a nulstr for a standard cascade of configuration directories,
+ * suitable to pass to conf_files_list_nulstr or config_parse_many. */
+#define CONF_DIRS_NULSTR(n) \
+        "/etc/" n ".d\0" \
+        "/run/" n ".d\0" \
+        "/usr/local/lib/" n ".d\0" \
+        "/usr/lib/" n ".d\0" \
+        CONF_DIR_SPLIT_USR(n)
+
+#ifdef HAVE_SPLIT_USR
+#define CONF_DIR_SPLIT_USR(n) "/lib/" n ".d\0"
+#else
+#define CONF_DIR_SPLIT_USR(n)
+#endif
+
 /* Define C11 thread_local attribute even on older gcc compiler
  * version */
 #ifndef thread_local
diff --git a/src/sysctl/sysctl.c b/src/sysctl/sysctl.c
index 809e59b71f..edebe501d1 100644
--- a/src/sysctl/sysctl.c
+++ b/src/sysctl/sysctl.c
@@ -38,15 +38,7 @@
 
 static char **arg_prefixes = NULL;
 
-static const char conf_file_dirs[] =
-        "/etc/sysctl.d\0"
-        "/run/sysctl.d\0"
-        "/usr/local/lib/sysctl.d\0"
-        "/usr/lib/sysctl.d\0"
-#ifdef HAVE_SPLIT_USR
-        "/lib/sysctl.d\0"
-#endif
-        ;
+static const char conf_file_dirs[] = CONF_DIRS_NULSTR("sysctl");
 
 static char* normalize_sysctl(char *s) {
         char *n;
diff --git a/src/sysusers/sysusers.c b/src/sysusers/sysusers.c
index 04e973ac17..7820e84983 100644
--- a/src/sysusers/sysusers.c
+++ b/src/sysusers/sysusers.c
@@ -67,15 +67,7 @@ typedef struct Item {
 
 static char *arg_root = NULL;
 
-static const char conf_file_dirs[] =
-        "/etc/sysusers.d\0"
-        "/run/sysusers.d\0"
-        "/usr/local/lib/sysusers.d\0"
-        "/usr/lib/sysusers.d\0"
-#ifdef HAVE_SPLIT_USR
-        "/lib/sysusers.d\0"
-#endif
-        ;
+static const char conf_file_dirs[] = CONF_DIRS_NULSTR("sysusers");
 
 static Hashmap *users = NULL, *groups = NULL;
 static Hashmap *todo_uids = NULL, *todo_gids = NULL;
diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index 1e4675f87e..23fd6ca3bc 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -117,15 +117,7 @@ static char **arg_include_prefixes = NULL;
 static char **arg_exclude_prefixes = NULL;
 static char *arg_root = NULL;
 
-static const char conf_file_dirs[] =
-        "/etc/tmpfiles.d\0"
-        "/run/tmpfiles.d\0"
-        "/usr/local/lib/tmpfiles.d\0"
-        "/usr/lib/tmpfiles.d\0"
-#ifdef HAVE_SPLIT_USR
-        "/lib/tmpfiles.d\0"
-#endif
-        ;
+static const char conf_file_dirs[] = CONF_DIRS_NULSTR("tmpfiles");
 
 #define MAX_DEPTH 256