Reuse VM ids.

[Ori Bernstein]

Keep a list of known vms, and reuse the VM IDs. This means that when using
'-L', the IP addresses of the VMs are stable.

diff --git usr.sbin/vmd/config.c usr.sbin/vmd/config.c
index af12b790002..522bae32501 100644
--- usr.sbin/vmd/config.c
+++ usr.sbin/vmd/config.c
@@ -61,7 +61,10 @@ config_init(struct vmd *env)
        if (what & CONFIG_VMS) {
                if ((env->vmd_vms = calloc(1, sizeof(*env->vmd_vms))) == NULL)
                        return (-1);
+               if ((env->vmd_known = calloc(1, sizeof(*env->vmd_known))) == 
NULL)
+                       return (-1);
                TAILQ_INIT(env->vmd_vms);
+               TAILQ_INIT(env->vmd_known);
        }
        if (what & CONFIG_SWITCHES) {
                if ((env->vmd_switches = calloc(1,
diff --git usr.sbin/vmd/vmd.c usr.sbin/vmd/vmd.c
index 18a5e0d3d5d..732691b4381 100644
--- usr.sbin/vmd/vmd.c
+++ usr.sbin/vmd/vmd.c
@@ -1169,6 +1169,27 @@ vm_remove(struct vmd_vm *vm, const char *caller)
        free(vm);
 }
 
+static uint32_t
+claim_vmid(const char *name)
+{
+       struct name2id *n2i = NULL;
+
+       TAILQ_FOREACH(n2i, env->vmd_known, entry)
+               if (strcmp(n2i->name, name) == 0)
+                       return n2i->id;
+
+       if (++env->vmd_nvm == 0)
+               fatalx("too many vms");
+       if ((n2i = calloc(1, sizeof(struct name2id))) == NULL)
+               fatalx("could not alloc vm name");
+       n2i->id = env->vmd_nvm;
+       if (strlcpy(n2i->name, name, sizeof(n2i->name)) >= sizeof(n2i->name))
+               fatalx("overlong vm name");
+       TAILQ_INSERT_TAIL(env->vmd_known, n2i, entry);
+
+       return n2i->id;
+}
+
 int
 vm_register(struct privsep *ps, struct vmop_create_params *vmc,
     struct vmd_vm **ret_vm, uint32_t id, uid_t uid)
@@ -1300,11 +1321,8 @@ vm_register(struct privsep *ps, struct 
vmop_create_params *vmc,
        vm->vm_cdrom = -1;
        vm->vm_iev.ibuf.fd = -1;
 
-       if (++env->vmd_nvm == 0)
-               fatalx("too many vms");
-
        /* Assign a new internal Id if not specified */
-       vm->vm_vmid = id == 0 ? env->vmd_nvm : id;
+       vm->vm_vmid = (id == 0) ? claim_vmid(vcp->vcp_name) : id;
 
        log_debug("%s: registering vm %d", __func__, vm->vm_vmid);
        TAILQ_INSERT_TAIL(env->vmd_vms, vm, vm_entry);
diff --git usr.sbin/vmd/vmd.h usr.sbin/vmd/vmd.h
index b7c012854e8..86fad536e59 100644
--- usr.sbin/vmd/vmd.h
+++ usr.sbin/vmd/vmd.h
@@ -276,6 +276,13 @@ struct vmd_user {
 };
 TAILQ_HEAD(userlist, vmd_user);
 
+struct name2id {
+       char                    name[VMM_MAX_NAME_LEN];
+       int32_t                 id;
+       TAILQ_ENTRY(name2id)    entry;
+};
+TAILQ_HEAD(name2idlist, name2id);
+
 struct address {
        struct sockaddr_storage  ss;
        int                      prefixlen;
@@ -300,6 +307,7 @@ struct vmd {
 
        uint32_t                 vmd_nvm;
        struct vmlist           *vmd_vms;
+       struct name2idlist      *vmd_known;
        uint32_t                 vmd_nswitches;
        struct switchlist       *vmd_switches;
        struct userlist         *vmd_users;

-- 
    Ori Bernstein