From cccc74b5146cb1b88facef29a530c653dbe0cb90 Mon Sep 17 00:00:00 2001
From: Daniel Lezcano <daniel.lezcano@free.fr>
Date: Mon, 13 Sep 2010 15:36:20 +0200
Subject: [PATCH] configure container architecture

When a container is installed with 32bits binaries while we are
running on a 64bits host, inside the container we are seen as
64bits arch. That leads to some problems for the package updates
because the scripts will download 64bits packages instead of 32bits.

This patch defines a configuration variable to set the architecture
of the container.

lxc.arch = i686 | x86 | x86_64 | amd64

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
---
 doc/lxc.conf.sgml.in | 32 ++++++++++++++++++++++++++++++++
 src/lxc/conf.c       | 22 ++++++++++++++++++++++
 src/lxc/conf.h       |  1 +
 src/lxc/confile.c    | 31 +++++++++++++++++++++++++++++++
 4 files changed, 86 insertions(+)

diff --git a/doc/lxc.conf.sgml.in b/doc/lxc.conf.sgml.in
index a6454b919..f975d57e7 100644
--- a/doc/lxc.conf.sgml.in
+++ b/doc/lxc.conf.sgml.in
@@ -75,6 +75,38 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
       the line is a comment.
     </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>
diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index c95521365..8cb8e2050 100644
--- a/src/lxc/conf.c
+++ b/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;
diff --git a/src/lxc/conf.h b/src/lxc/conf.h
index 32135b656..b12a3466e 100644
--- a/src/lxc/conf.h
+++ b/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;
diff --git a/src/lxc/confile.c b/src/lxc/confile.c
index e2c015d7c..610ca154b 100644
--- a/src/lxc/confile.c
+++ b/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);