1 files changed, 64 insertions, 0 deletions
diff --git a/src/udev/net/naming-scheme.c b/src/udev/net/naming-scheme.c
new file mode 100644
index 0000000..27cede5
--- /dev/null
+++ b/src/udev/net/naming-scheme.c
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#include "alloc-util.h"
+#include "naming-scheme.h"
+#include "proc-cmdline.h"
+#include "string-util.h"
+
+static const NamingScheme naming_schemes[] = {
+        { "v238", NAMING_V238 },
+        { "v239", NAMING_V239 },
+        { "v240", NAMING_V240 },
+        /* … add more schemes here, as the logic to name devices is updated … */
+};
+
+static const NamingScheme* naming_scheme_from_name(const char *name) {
+        size_t i;
+
+        if (streq(name, "latest"))
+                return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
+
+        for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
+                if (streq(naming_schemes[i].name, name))
+                        return naming_schemes + i;
+
+        return NULL;
+}
+
+const NamingScheme* naming_scheme(void) {
+        static const NamingScheme *cache = NULL;
+        _cleanup_free_ char *buffer = NULL;
+        const char *e, *k;
+
+        if (cache)
+                return cache;
+
+        /* Acquire setting from the kernel command line */
+        (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
+
+        /* Also acquire it from an env var */
+        e = getenv("NET_NAMING_SCHEME");
+        if (e) {
+                if (*e == ':') {
+                        /* If prefixed with ':' the kernel cmdline takes precedence */
+                        k = buffer ?: e + 1;
+                } else
+                        k = e; /* Otherwise the env var takes precedence */
+        } else
+                k = buffer;
+
+        if (k) {
+                cache = naming_scheme_from_name(k);
+                if (cache) {
+                        log_info("Using interface naming scheme '%s'.", cache->name);
+                        return cache;
+                }
+
+                log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
+        }
+
+        cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
+        assert(cache);
+        log_info("Using default interface naming scheme '%s'.", cache->name);
+
+        return cache;
+}