locale-util: allow overriding locale directory via environment

src/basic/locale-util.c

@@ -55,6 +55,15 @@ static char* normalize_locale(const char *name) {
         return strdup(name);
 }
 
+static const char* get_locale_dir(void) {
+        return secure_getenv("SYSTEMD_LOCALE_DIRECTORY") ?:
+#ifdef __GLIBC__
+                "/usr/lib/locale/";
+#else
+                "/usr/share/i18n/locales/musl/";
+#endif
+}
+
 #ifdef __GLIBC__
 static int add_locales_from_archive(Set *locales) {
         /* Stolen from glibc... */
@@ -94,7 +103,11 @@ static int add_locales_from_archive(Set *locales) {
 
         assert(locales);
 
-        _cleanup_close_ int fd = open("/usr/lib/locale/locale-archive", O_RDONLY|O_NOCTTY|O_CLOEXEC);
+        _cleanup_free_ char *locale_archive_file = path_join(get_locale_dir(), "locale-archive");
+        if (!locale_archive_file)
+                return -ENOMEM;
+
+        _cleanup_close_ int fd = open(locale_archive_file, O_RDONLY|O_NOCTTY|O_CLOEXEC);
         if (fd < 0)
                 return errno == ENOENT ? 0 : -errno;
 
@@ -162,7 +175,7 @@ static int add_locales_from_libdir(Set *locales) {
 
         assert(locales);
 
-        dir = opendir("/usr/lib/locale");
+        dir = opendir(get_locale_dir());
         if (!dir)
                 return errno == ENOENT ? 0 : -errno;
 
@@ -191,7 +204,7 @@ static int add_locales_for_musl(Set *locales) {
 
         assert(locales);
 
-        _cleanup_closedir_ DIR *dir = opendir("/usr/share/i18n/locales/musl/");
+        _cleanup_closedir_ DIR *dir = opendir(get_locale_dir());
         if (!dir)
                 return errno == ENOENT ? 0 : -errno;
 
@@ -313,7 +326,7 @@ int locale_is_installed(const char *name) {
 
         /* musl's newlocale() always succeeds and provides a fake locale object even when the locale does
          * not exist. Hence, we need to explicitly check if the locale file exists. */
-        _cleanup_free_ char *p = path_join("/usr/share/i18n/locales/musl/", name);
+        _cleanup_free_ char *p = path_join(get_locale_dir(), name);
         if (!p)
                 return -ENOMEM;