configure container architecture

doc/lxc.conf.sgml.in

@@ -76,6 +76,38 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     </para>
 
     <refsect2>
+      <title>Architecture</title>
+      <para>
+	Allows to set the architecture for the container. For example,
+	set a 32bits architecture for a container running 32bits
+	binaries on a 64bits host. That fix the container scripts
+	which rely on the architecture to do some work like
+	downloading the packages.
+      </para>
+
+      <variablelist>
+	<varlistentry>
+	  <term>
+	    <option>lxc.arch</option>
+	  </term>
+	  <listitem>
+	    <para>
+	      Specify the architecture for the container.
+	    </para>
+	    <para>
+	      Valid options are
+	      <option>x86</option>,
+	      <option>i686</option>,
+	      <option>x86_64</option>,
+	      <option>amd64</option>
+	    </para>
+	  </listitem>
+	</varlistentry>
+      </variablelist>
+
+    </refsect2>
+
+    <refsect2>
       <title>Hostname</title>
       <para>
 	The utsname section defines the hostname to be set for the

src/lxc/conf.c

@@ -40,6 +40,7 @@
 #include <sys/mman.h>
 #include <sys/prctl.h>
 #include <sys/capability.h>
+#include <sys/personality.h>
 
 #include <arpa/inet.h>
 #include <fcntl.h>
@@ -655,6 +656,21 @@ out:
 	return 0;
 }
 
+static int setup_personality(int persona)
+{
+	if (persona == -1)
+		return 0;
+
+	if (personality(persona) < 0) {
+		SYSERROR("failed to set personality to '0x%x'", persona);
+		return -1;
+	}
+
+	INFO("set personality to '0x%x'", persona);
+
+	return 0;
+}
+
 static int setup_console(const struct lxc_rootfs *rootfs,
 			 const struct lxc_console *console)
 {
@@ -1125,6 +1141,7 @@ struct lxc_conf *lxc_conf_init(void)
 	}
 	memset(new, 0, sizeof(*new));
 
+	new->personality = -1;
 	new->console.path = NULL;
 	new->console.peer = -1;
 	new->console.master = -1;
@@ -1475,6 +1492,11 @@ int lxc_setup(const char *name, struct lxc_conf *lxc_conf)
 		return -1;
 	}
 
+	if (setup_personality(lxc_conf->personality)) {
+		ERROR("failed to setup personality");
+		return -1;
+	}
+
 	if (setup_caps(&lxc_conf->caps)) {
 		ERROR("failed to drop capabilities");
 		return -1;

src/lxc/conf.h

@@ -194,6 +194,7 @@ struct lxc_conf {
 	int tty;
 	int pts;
 	int reboot;
+	int personality;
 	struct utsname *utsname;
 	struct lxc_list cgroup;
 	struct lxc_list network;

src/lxc/confile.c

@@ -31,6 +31,7 @@
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/utsname.h>
+#include <sys/personality.h>
 #include <arpa/inet.h>
 #include <netinet/in.h>
 #include <net/if.h>
@@ -43,6 +44,7 @@
 
 lxc_log_define(lxc_confile, lxc);
 
+static int config_personality(const char *, char *, struct lxc_conf *);
 static int config_pts(const char *, char *, struct lxc_conf *);
 static int config_tty(const char *, char *, struct lxc_conf *);
 static int config_cgroup(const char *, char *, struct lxc_conf *);
@@ -74,6 +76,7 @@ struct config {
 
 static struct config config[] = {
 
+	{ "lxc.arch",                 config_personality          },
 	{ "lxc.pts",                  config_pts                  },
 	{ "lxc.tty",                  config_tty                  },
 	{ "lxc.cgroup",               config_cgroup               },
@@ -475,6 +478,34 @@ static int config_network_ipv6(const char *key, char *value,
 	return 0;
 }
 
+static int config_personality(const char *key, char *value,
+			      struct lxc_conf *lxc_conf)
+{
+	struct per_name {
+		char *name;
+		int per;
+	} pername[4] = {
+		{ "x86", PER_LINUX32 },
+		{ "i686", PER_LINUX32 },
+		{ "x86_64", PER_LINUX },
+		{ "amd64", PER_LINUX },
+	};
+
+	int i;
+
+	for (i = 0; i < sizeof(pername); i++) {
+
+		if (strcmp(pername[i].name, value))
+		    continue;
+
+		lxc_conf->personality = pername[i].per;
+		return 0;
+	}
+
+	ERROR("unsupported personality '%s'", value);
+	return -1;
+}
+
 static int config_pts(const char *key, char *value, struct lxc_conf *lxc_conf)
 {
 	int maxpts = atoi(value);