udev,network: use standard paths for .network and .link files

This centralizes the configuration to one header file.
/usr/local/lib is now included in the search list, and documentation is
updated accordingly.

man/systemd.network.xml

@@ -37,17 +37,17 @@
     <para>The main network file must have the extension <filename>.network</filename>; other
     extensions are ignored. Networks are applied to links whenever the links appear.</para>
 
-    <para>The <filename>.network</filename> files are read from the files located in the system
-    network directory <filename>/usr/lib/systemd/network</filename>, the volatile runtime network
-    directory <filename>/run/systemd/network</filename> and the local administration network
-    directory <filename>/etc/systemd/network</filename>. All configuration files are collectively
-    sorted and processed in lexical order, regardless of the directories in which they live.
-    However, files with identical filenames replace each other. Files in <filename>/etc</filename>
-    have the highest priority, files in <filename>/run</filename> take precedence over files with
-    the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
-    configuration file with a local file if needed. As a special case, an empty file (file size 0)
-    or symlink with the same name pointing to <filename>/dev/null</filename> disables the
-    configuration file entirely (it is "masked").</para>
+    <para>The <filename>.network</filename> files are read from the files located in the system network
+    directories <filename>/usr/lib/systemd/network</filename> and
+    <filename>/usr/local/lib/systemd/network</filename>, the volatile runtime network directory
+    <filename>/run/systemd/network</filename> and the local administration network directory
+    <filename>/etc/systemd/network</filename>. All configuration files are collectively sorted and processed
+    in lexical order, regardless of the directories in which they live. However, files with identical
+    filenames replace each other. Files in <filename>/etc</filename> have the highest priority, files in
+    <filename>/run</filename> take precedence over files with the same name under
+    <filename>/usr</filename>. This can be used to override a system-supplied configuration file with a local
+    file if needed. As a special case, an empty file (file size 0) or symlink with the same name pointing to
+    <filename>/dev/null</filename> disables the configuration file entirely (it is "masked").</para>
 
     <para>Along with the network file <filename>foo.network</filename>, a "drop-in" directory
     <filename>foo.network.d/</filename> may exist. All files with the suffix
@@ -60,9 +60,7 @@
     <filename>/run/systemd/network</filename> directories. Drop-in files in
     <filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
     take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
-    directories take precedence over the main netdev file wherever located. (Of course, since
-    <filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
-    unlikely drop-ins should be used in either of those places.)</para>
+    directories take precedence over the main netdev file wherever located.</para>
 
     <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
     nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically

src/libsystemd-network/network-internal.h

@@ -8,7 +8,9 @@
 
 #include "condition.h"
 #include "conf-parser.h"
+#include "def.h"
 #include "set.h"
+#include "strv.h"
 
 #define LINK_BRIDGE_PORT_PRIORITY_INVALID 128
 #define LINK_BRIDGE_PORT_PRIORITY_MAX 63
@@ -54,3 +56,5 @@ int deserialize_dhcp_routes(struct sd_dhcp_route **ret, size_t *ret_size, size_t
 
 /* It is not necessary to add deserialize_dhcp_option(). Use unhexmem() instead. */
 int serialize_dhcp_option(FILE *f, const char *key, const void *data, size_t size);
+
+#define NETWORK_DIRS ((const char* const*) CONF_PATHS_STRV("systemd/network"))

src/network/netdev/netdev.c

@@ -661,7 +661,7 @@ int netdev_load_one(Manager *manager, const char *filename) {
         };
 
         dropin_dirname = strjoina(basename(filename), ".d");
-        r = config_parse_many(filename, network_dirs, dropin_dirname,
+        r = config_parse_many(filename, NETWORK_DIRS, dropin_dirname,
                               "Match\0NetDev\0",
                               config_item_perf_lookup, network_netdev_gperf_lookup,
                               CONFIG_PARSE_WARN|CONFIG_PARSE_RELAXED, netdev_raw);
@@ -702,7 +702,7 @@ int netdev_load_one(Manager *manager, const char *filename) {
         if (NETDEV_VTABLE(netdev)->init)
                 NETDEV_VTABLE(netdev)->init(netdev);
 
-        r = config_parse_many(filename, network_dirs, dropin_dirname,
+        r = config_parse_many(filename, NETWORK_DIRS, dropin_dirname,
                               NETDEV_VTABLE(netdev)->sections,
                               config_item_perf_lookup, network_netdev_gperf_lookup,
                               CONFIG_PARSE_WARN, netdev);
@@ -802,7 +802,7 @@ int netdev_load(Manager *manager) {
 
         hashmap_clear_with_destructor(manager->netdevs, netdev_unref);
 
-        r = conf_files_list_strv(&files, ".netdev", NULL, 0, network_dirs);
+        r = conf_files_list_strv(&files, ".netdev", NULL, 0, NETWORK_DIRS);
         if (r < 0)
                 return log_error_errno(r, "Failed to enumerate netdev files: %m");
 

src/network/networkd-manager.c

@@ -18,6 +18,7 @@
 #include "fileio.h"
 #include "local-addresses.h"
 #include "netlink-util.h"
+#include "network-internal.h"
 #include "networkd-manager.h"
 #include "ordered-set.h"
 #include "path-util.h"
@@ -29,15 +30,6 @@
 /* use 8 MB for receive socket kernel queue. */
 #define RCVBUF_SIZE    (8*1024*1024)
 
-const char* const network_dirs[] = {
-        "/etc/systemd/network",
-        "/run/systemd/network",
-        "/usr/lib/systemd/network",
-#if HAVE_SPLIT_USR
-        "/lib/systemd/network",
-#endif
-        NULL};
-
 static int setup_default_address_pool(Manager *m) {
         AddressPool *p;
         int r;
@@ -1485,7 +1477,7 @@ int manager_load_config(Manager *m) {
         int r;
 
         /* update timestamp */
-        paths_check_timestamp(network_dirs, &m->network_dirs_ts_usec, true);
+        paths_check_timestamp(NETWORK_DIRS, &m->network_dirs_ts_usec, true);
 
         r = netdev_load(m);
         if (r < 0)
@@ -1499,7 +1491,7 @@ int manager_load_config(Manager *m) {
 }
 
 bool manager_should_reload(Manager *m) {
-        return paths_check_timestamp(network_dirs, &m->network_dirs_ts_usec, false);
+        return paths_check_timestamp(NETWORK_DIRS, &m->network_dirs_ts_usec, false);
 }
 
 int manager_rtnl_enumerate_links(Manager *m) {

src/network/networkd-manager.h

@@ -18,8 +18,6 @@
 #include "networkd-link.h"
 #include "networkd-network.h"
 
-extern const char* const network_dirs[];
-
 struct Manager {
         sd_netlink *rtnl;
         /* lazy initialized */

src/network/networkd-network.c

@@ -211,7 +211,7 @@ int network_load_one(Manager *manager, const char *filename) {
                 .ipv6_accept_ra_route_table = RT_TABLE_MAIN,
         };
 
-        r = config_parse_many(filename, network_dirs, dropin_dirname,
+        r = config_parse_many(filename, NETWORK_DIRS, dropin_dirname,
                               "Match\0"
                               "Link\0"
                               "Network\0"
@@ -291,7 +291,7 @@ int network_load(Manager *manager) {
         while ((network = manager->networks))
                 network_free(network);
 
-        r = conf_files_list_strv(&files, ".network", NULL, 0, network_dirs);
+        r = conf_files_list_strv(&files, ".network", NULL, 0, NETWORK_DIRS);
         if (r < 0)
                 return log_error_errno(r, "Failed to enumerate network files: %m");
 

src/udev/net/link-config.c

@@ -8,6 +8,7 @@
 #include "alloc-util.h"
 #include "conf-files.h"
 #include "conf-parser.h"
+#include "def.h"
 #include "device-util.h"
 #include "ethtool-util.h"
 #include "fd-util.h"
@@ -36,18 +37,9 @@ struct link_config_ctx {
 
         sd_netlink *rtnl;
 
-        usec_t link_dirs_ts_usec;
+        usec_t network_dirs_ts_usec;
 };
 
-static const char* const link_dirs[] = {
-        "/etc/systemd/network",
-        "/run/systemd/network",
-        "/usr/lib/systemd/network",
-#if HAVE_SPLIT_USR
-        "/lib/systemd/network",
-#endif
-        NULL};
-
 static void link_config_free(link_config *link) {
         if (!link)
                 return;
@@ -216,9 +208,9 @@ int link_config_load(link_config_ctx *ctx) {
         }
 
         /* update timestamp */
-        paths_check_timestamp(link_dirs, &ctx->link_dirs_ts_usec, true);
+        paths_check_timestamp(NETWORK_DIRS, &ctx->network_dirs_ts_usec, true);
 
-        r = conf_files_list_strv(&files, ".link", NULL, 0, link_dirs);
+        r = conf_files_list_strv(&files, ".link", NULL, 0, NETWORK_DIRS);
         if (r < 0)
                 return log_error_errno(r, "failed to enumerate link files: %m");
 
@@ -232,7 +224,7 @@ int link_config_load(link_config_ctx *ctx) {
 }
 
 bool link_config_should_reload(link_config_ctx *ctx) {
-        return paths_check_timestamp(link_dirs, &ctx->link_dirs_ts_usec, false);
+        return paths_check_timestamp(NETWORK_DIRS, &ctx->network_dirs_ts_usec, false);
 }
 
 int link_config_get(link_config_ctx *ctx, sd_device *device, link_config **ret) {