network: implement lxc_get_netdev_by_idx()

lxc_get_netdev_by_idx() takes care of checking whether a given netdev struct
for a given index is already allocated. If so it returns a pointer to it to the
caller.
If it doesn't find it it will allocate a new netdev struct and insert it into
the network list at the right position. For example, let's say you have the
following networks defined in your config file:

lxc.network.0.type=veth
lxc.network.0.link=lxcbr0
lxc.network.0.name=eth0
lxc.network.0.flags=up

lxc.network.3.type=veth
lxc.network.3.link=lxcbr0
lxc.network.3.name=eth1
lxc.network.3.flags=up
lxc.network.3.hwaddr = 00:16:3e:5d:7d:65

lxc.network.1.type=veth
lxc.network.1.link=lxcbr0
lxc.network.1.name=eth0
lxc.network.1.flags=up

lxc_get_netdev_by_idx() will take care that the internal network list appears
in the order:

0
1
3

The ordering of the keys themselves can also be random, meaning you could do:

lxc.network.3.type=veth
lxc.network.0.link=lxcbr0
lxc.network.0.name=eth0
lxc.network.3.hwaddr = 00:16:3e:5d:7d:65
lxc.network.0.flags=up
lxc.network.3.flags=up
lxc.network.0.type=veth
lxc.network.3.link=lxcbr0
lxc.network.3.name=eth1

and lxc_get_netdev_by_idx() would still figure out the correct ordering since
it keeps track of the index.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/confile_utils.c b/src/lxc/confile_utils.c
index 8da239129861c23e8ce958644c9589a09ec159ec..6118762e1f17d9fa4cac228c058bf7ffafc81045 100644 (file)
--- a/src/lxc/confile_utils.c
+++ b/src/lxc/confile_utils.c
@@ -17,13 +17,22 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include "config.h"
+
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "conf.h"
+#include "confile.h"
+#include "confile_utils.h"
+#include "error.h"
 #include "log.h"
+#include "list.h"
 #include "utils.h"
 
+lxc_log_define(lxc_confile_utils, lxc);
+
 int parse_idmaps(const char *idmap, char *type, unsigned long *nsid,
                 unsigned long *hostid, unsigned long *range)
 {
@@ -156,3 +165,73 @@ bool lxc_config_value_empty(const char *value)
 
        return true;
 }
+
+struct lxc_netdev *lxc_find_netdev_by_idx(struct lxc_conf *conf,
+                                         unsigned int idx)
+{
+       struct lxc_netdev *netdev = NULL;
+       struct lxc_list *networks = &conf->network;
+       struct lxc_list *insert = networks;
+
+       /* lookup network */
+       if (lxc_list_empty(networks))
+               return NULL;
+
+       lxc_list_for_each(insert, networks) {
+               netdev = insert->elem;
+               if (netdev->idx >= idx)
+                       break;
+       }
+
+       /* network already exists */
+       if (netdev->idx == idx)
+               return netdev;
+
+       return NULL;
+}
+
+/* Takes care of finding the correct netdev struct in the networks list or
+ * allocates a new one if it couldn't be found.
+ */
+struct lxc_netdev *lxc_get_netdev_by_idx(struct lxc_conf *conf,
+                                        unsigned int idx)
+{
+       struct lxc_list *newlist;
+       struct lxc_netdev *netdev = NULL;
+       struct lxc_list *networks = &conf->network;
+       struct lxc_list *insert = networks;
+
+       /* lookup network */
+       netdev = lxc_find_netdev_by_idx(conf, idx);
+       if (netdev)
+               return netdev;
+
+       /* network does not exist */
+       netdev = malloc(sizeof(*netdev));
+       if (!netdev)
+               return NULL;
+
+       memset(netdev, 0, sizeof(*netdev));
+       lxc_list_init(&netdev->ipv4);
+       lxc_list_init(&netdev->ipv6);
+
+       /* give network a unique index */
+       netdev->idx = idx;
+
+       /* prepare new list */
+       newlist = malloc(sizeof(*newlist));
+       if (!newlist) {
+               free(netdev);
+               return NULL;
+       }
+
+       lxc_list_init(newlist);
+       newlist->elem = netdev;
+
+       /* Insert will now point to the correct position to insert the new
+        * netdev.
+        */
+       lxc_list_add_tail(insert, newlist);
+
+       return netdev;
+}

diff --git a/src/lxc/confile_utils.h b/src/lxc/confile_utils.h
index 35ac10b2e451501dabcd173b32be741b261d0ada..7b41af156f3c4e5c7d1a35f9400053373db7e168 100644 (file)
--- a/src/lxc/confile_utils.h
+++ b/src/lxc/confile_utils.h
@@ -22,9 +22,15 @@
 
 #include <stdbool.h>
 
+#include "conf.h"
+
 extern int parse_idmaps(const char *idmap, char *type, unsigned long *nsid,
                        unsigned long *hostid, unsigned long *range);
 
 extern bool lxc_config_value_empty(const char *value);
+extern struct lxc_netdev *lxc_find_netdev_by_idx(struct lxc_conf *conf,
+                                                unsigned int idx);
+extern struct lxc_netdev *lxc_get_netdev_by_idx(struct lxc_conf *conf,
+                                               unsigned int idx);
 
 #endif /* __LXC_CONFILE_UTILS_H */