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