src/udev/net/naming-scheme.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #include "alloc-util.h"
   3 #include "naming-scheme.h"
   4 #include "proc-cmdline.h"
   5 #include "string-util.h"
   6
   7 static const NamingScheme naming_schemes[] = {
   8         { "v238", NAMING_V238 },
   9         { "v239", NAMING_V239 },
  10         { "v240", NAMING_V240 },
  11         { "v243", NAMING_V243 },
  12         /* … add more schemes here, as the logic to name devices is updated … */
  13 };
  14
  15 static const NamingScheme* naming_scheme_from_name(const char *name) {
  16         size_t i;
  17
  18         if (streq(name, "latest"))
  19                 return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
  20
  21         for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
  22                 if (streq(naming_schemes[i].name, name))
  23                         return naming_schemes + i;
  24
  25         return NULL;
  26 }
  27
  28 const NamingScheme* naming_scheme(void) {
  29         static const NamingScheme *cache = NULL;
  30         _cleanup_free_ char *buffer = NULL;
  31         const char *e, *k;
  32
  33         if (cache)
  34                 return cache;
  35
  36         /* Acquire setting from the kernel command line */
  37         (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
  38
  39         /* Also acquire it from an env var */
  40         e = getenv("NET_NAMING_SCHEME");
  41         if (e) {
  42                 if (*e == ':') {
  43                         /* If prefixed with ':' the kernel cmdline takes precedence */
  44                         k = buffer ?: e + 1;
  45                 } else
  46                         k = e; /* Otherwise the env var takes precedence */
  47         } else
  48                 k = buffer;
  49
  50         if (k) {
  51                 cache = naming_scheme_from_name(k);
  52                 if (cache) {
  53                         log_info("Using interface naming scheme '%s'.", cache->name);
  54                         return cache;
  55                 }
  56
  57                 log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
  58         }
  59
  60         cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
  61         assert(cache);
  62         log_info("Using default interface naming scheme '%s'.", cache->name);
  63
  64         return cache;
  65 }