Switch from use of LXCPATH to a configurable default_lxc_path

Here is a patch to introduce a configurable system-wide
lxcpath.  It seems to work with lxc-create, lxc-start,
and basic python3 lxc usage through the api.

For shell functions, a new /usr/share/lxc/lxc.functions is
introduced which sets some of the basic global variables,
including evaluating the right place for lxc_path.

I have not converted any of the other python code, as I was
not sure where we should keep the common functions (i.e.
for now just default_lxc_path()).

configure.ac: add an option for setting the global config file name.
utils: add a default_lxc_path() function
Use default_lxc_path in .c files
define get_lxc_path() and set_lxc_path() in C api
use get_lxc_path() in lua api
create sh helper for getting default path from config file
fix up scripts to use lxc.functions

Changelog:
  feb6:
	fix lxc_path in lxc.functions
	utils.c: as Dwight pointed out, don't close a NULL fin.
	utils.c: fix the parsing of lxcpath line
	lxc-start: print which rcfile we are using
	commands.c: As Dwight alluded to, the sockname handling was just
	   ridiculous.  Clean that up.
	use Dwight's recommendation for lxc.functions path: $datadir/lxc
	make lxccontainer->get_config_path() return const char *
		Per Dwight's suggestion, much nicer than returning strdup.
  feb6 (v2):
        lxccontainer: set c->config_path before using it.
	convert legacy lxc-ls

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

configure.ac

@@ -161,12 +161,21 @@ AC_ARG_ENABLE([tests],
 AM_CONDITIONAL([ENABLE_TESTS], [test "x$enable_tests" = "xyes"])
 
 # LXC container path, where the containers are actually stored
+# This is overriden by an entry in the file called LXCCONF
+# (i.e. /etc/lxc/lxc.conf)
 AC_ARG_WITH([config-path],
 	[AC_HELP_STRING(
 		[--with-config-path=dir],
 		[lxc configuration repository path]
 	)], [], [with_config_path=['${localstatedir}/lib/lxc']])
 
+# The path of the global lxc configuration file.
+AC_ARG_WITH([global-conf],
+	[AC_HELP_STRING(
+		[--with-global-conf=dir],
+		[global lxc configuration file]
+	)], [], [with_global_conf=['${sysconfdir}/lxc/lxc.conf']])
+
 # Rootfs path, where the container mount structure is assembled
 AC_ARG_WITH([rootfs-path],
 	[AC_HELP_STRING(
@@ -207,6 +216,7 @@ AS_AC_EXPAND(DOCDIR, "$docdir")
 AS_AC_EXPAND(LXC_DEFAULT_CONF, "$defaultconf")
 AS_AC_EXPAND(LXC_GENERATE_DATE, "$(date)")
 AS_AC_EXPAND(LXCPATH, "$with_config_path")
+AS_AC_EXPAND(LXC_GLOBAL_CONF, "$with_global_conf")
 AS_AC_EXPAND(LXCROOTFSMOUNT, "$with_rootfs_path")
 AS_AC_EXPAND(LXCTEMPLATEDIR, "$datadir/lxc/templates")
 AS_AC_EXPAND(LXCINITDIR, "$libexecdir")
@@ -355,6 +365,7 @@ AC_CONFIG_FILES([
 	src/lxc/lxc-start-ephemeral
 	src/lxc/lxc-destroy
 	src/lxc/legacy/lxc-ls
+	src/lxc/lxc.functions
 
 	src/python-lxc/Makefile
 	src/python-lxc/lxc/__init__.py

src/lua-lxc/core.c

@@ -339,7 +339,11 @@ static int lxc_version_get(lua_State *L) {
 }
 
 static int lxc_path_get(lua_State *L) {
-    lua_pushstring(L, LXCPATH);
+    struct lxc_container *c = lua_unboxpointer(L, 1, CONTAINER_TYPENAME);
+    const char *lxcpath;
+
+    lxcpath = c->get_config_path(c);
+    lua_pushstring(L, lxcpath);
     return 1;
 }
 

src/lxc/Makefile.am

@@ -88,6 +88,7 @@ endif
 AM_CFLAGS=-I$(top_srcdir)/src \
 	-DLXCROOTFSMOUNT=\"$(LXCROOTFSMOUNT)\" \
 	-DLXCPATH=\"$(LXCPATH)\" \
+	-DLXC_GLOBAL_CONF=\"$(LXC_GLOBAL_CONF)\" \
 	-DLXCINITDIR=\"$(LXCINITDIR)\" \
 	-DLXCTEMPLATEDIR=\"$(LXCTEMPLATEDIR)\" \
 	-DLOGPATH=\"$(LOGPATH)\"
@@ -164,6 +165,9 @@ bin_PROGRAMS = \
 pkglibexec_PROGRAMS = \
 	lxc-init
 
+#pkglibexec_SCRIPTS = \
+#	lxc.functions
+
 AM_LDFLAGS = -Wl,-E
 if ENABLE_RPATH
 AM_LDFLAGS += -Wl,-rpath -Wl,$(libdir)
@@ -192,6 +196,8 @@ lxc_wait_SOURCES = lxc_wait.c
 lxc_kill_SOURCES = lxc_kill.c
 
 install-exec-local: install-soPROGRAMS
+	mkdir -p $(DESTDIR)$(datadir)/lxc
+	install -c -m 644 lxc.functions $(DESTDIR)$(datadir)/lxc
 	mv $(DESTDIR)$(libdir)/liblxc.so $(DESTDIR)$(libdir)/liblxc.so.$(VERSION)
 	/sbin/ldconfig -l $(DESTDIR)$(libdir)/liblxc.so.$(VERSION)
 	cd $(DESTDIR)$(libdir); \

src/lxc/commands.c

@@ -30,10 +30,13 @@
 #include <sys/un.h>
 #include <sys/poll.h>
 #include <sys/param.h>
+#include <malloc.h>
+#include <stdlib.h>
 
 #include <lxc/log.h>
 #include <lxc/conf.h>
 #include <lxc/start.h>	/* for struct lxc_handler */
+#include <lxc/utils.h>
 
 #include "commands.h"
 #include "mainloop.h"
@@ -56,7 +59,20 @@
 
 lxc_log_define(lxc_commands, lxc);
 
-#define abstractname LXCPATH "/%s/command"
+static int fill_sock_name(char *path, int len, const char *name) {
+	char *lxcpath = default_lxc_path();
+	int ret;
+	if (!lxcpath) {
+		ERROR("Out of memory getting lxcpath");
+		return -1;
+	}
+	ret = snprintf(path, len, "%s/%s/command", lxcpath, name);
+	if (ret < 0 || ret >= len) {
+		ERROR("Name too long");
+		return -1;
+	}
+	return 0;
+}
 
 static int receive_answer(int sock, struct lxc_answer *answer)
 {
@@ -75,14 +91,11 @@ static int __lxc_command(const char *name, struct lxc_command *command,
 	int sock, ret = -1;
 	char path[sizeof(((struct sockaddr_un *)0)->sun_path)] = { 0 };
 	char *offset = &path[1];
-	int rc, len;
+	int len;
 
 	len = sizeof(path)-1;
-	rc = snprintf(offset, len, abstractname, name);
-	if (rc < 0 || rc >= len) {
-		ERROR("Name too long");
+	if (fill_sock_name(offset, len, name))
 		return -1;
-	}
 
 	sock = lxc_af_unix_connect(path);
 	if (sock < 0 && errno == ECONNREFUSED) {
@@ -292,14 +305,11 @@ extern int lxc_command_init(const char *name, struct lxc_handler *handler)
 	int fd;
 	char path[sizeof(((struct sockaddr_un *)0)->sun_path)] = { 0 };
 	char *offset = &path[1];
-	int rc, len;
+	int len;
 
 	len = sizeof(path)-1;
-	rc = snprintf(offset, len, abstractname, name);
-	if (rc < 0 || rc >= len) {
-		ERROR("Name too long");
+	if (fill_sock_name(offset, len, name))
 		return -1;
-	}
 
 	fd = lxc_af_unix_open(path, SOCK_STREAM, 0);
 	if (fd < 0) {

src/lxc/conf.c

@@ -1519,15 +1519,23 @@ static int mount_entry_on_absolute_rootfs(struct mntent *mntent,
 	unsigned long mntflags;
 	char *mntdata;
 	int r, ret = 0, offset;
+	char *lxcpath;
 
 	if (parse_mntopts(mntent->mnt_opts, &mntflags, &mntdata) < 0) {
 		ERROR("failed to parse mount option '%s'", mntent->mnt_opts);
 		return -1;
 	}
 
+	lxcpath = default_lxc_path();
+	if (!lxcpath) {
+		ERROR("Out of memory");
+		return -1;
+	}
+
 	/* if rootfs->path is a blockdev path, allow container fstab to
-	 * use $LXCPATH/CN/rootfs as the target prefix */
-	r = snprintf(path, MAXPATHLEN, LXCPATH "/%s/rootfs", lxc_name);
+	 * use $lxcpath/CN/rootfs as the target prefix */
+	r = snprintf(path, MAXPATHLEN, "%s/%s/rootfs", lxcpath, lxc_name);
+	free(lxcpath);
 	if (r < 0 || r >= MAXPATHLEN)
 		goto skipvarlib;
 

src/lxc/legacy/lxc-ls.in

@@ -17,7 +17,7 @@
 # License along with this library; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
-lxc_path=@LXCPATH@
+. @DATADIR@/lxc/lxc.functions
 
 usage()
 {

src/lxc/lxc-clone.in

@@ -54,8 +54,7 @@ optarg_check() {
     [ -n "$2" ] || usage_err "option $1 requires an argument"
 }
 
-lxc_path=@LXCPATH@
-bindir=@BINDIR@
+. @DATADIR@/lxc/lxc.functions
 snapshot=no
 lxc_defsize=2G
 lxc_size=_unset

src/lxc/lxc-create.in

@@ -73,9 +73,7 @@ optarg_check() {
     fi
 }
 
-lxc_path=@LXCPATH@
-bindir=@BINDIR@
-templatedir=@LXCTEMPLATEDIR@
+. @DATADIR@/lxc/lxc.functions
 backingstore=_unset
 fstype=ext4
 fssize=500M

src/lxc/lxc-destroy.in

@@ -51,7 +51,7 @@ optarg_check() {
     fi
 }
 
-lxc_path=@LXCPATH@
+. @DATADIR@/lxc/lxc.functions
 force=0
 
 while [ $# -gt 0 ]; do

src/lxc/lxc-setcap.in

@@ -25,6 +25,8 @@
 # When the capabilities are set, a non root user can manage the containers.
 #
 
+. @DATADIR@/lxc/lxc.functions
+
 LXC_ATTACH_CAPS="cap_sys_admin,cap_dac_override"
 LXC_CREATE_CAPS="cap_sys_admin"
 LXC_NETSTAT_CAPS="cap_sys_admin"
@@ -62,23 +64,23 @@ lxc_setcaps()
     setcap $LXC_CHECKPOINT_CAPS=ep @BINDIR@/lxc-checkpoint
     setcap $LXC_INIT_CAPS=ep @LXCINITDIR@/lxc/lxc-init
 
-    test -e @LXCPATH@ || mkdir -p @LXCPATH@
-    chmod 0777 @LXCPATH@
+    test -e $lxc_path || mkdir -p $lxc_path
+    chmod 0777 $lxc_path
 }
 
 lxc_dropcaps()
 {
-    setcap -r @BINDIR@/lxc-attach
-    setcap -r @BINDIR@/lxc-create
-    setcap -r @BINDIR@/lxc-execute
-    setcap -r @BINDIR@/lxc-start
-    setcap -r @BINDIR@/lxc-restart
-    setcap -r @BINDIR@/lxc-unshare
-    setcap -r @BINDIR@/lxc-netstat
-    setcap -r @BINDIR@/lxc-checkpoint
-    setcap -r @LXCINITDIR@/lxc/lxc-init
+    setcap -r $bindir/lxc-attach
+    setcap -r $bindir/lxc-create
+    setcap -r $bindir/lxc-execute
+    setcap -r $bindir/lxc-start
+    setcap -r $bindir/lxc-restart
+    setcap -r $bindir/lxc-unshare
+    setcap -r $bindir/lxc-netstat
+    setcap -r $bindir/lxc-checkpoint
+    setcap -r $lxcinitdir/lxc/lxc-init
 
-    chmod 0755 @LXCPATH@
+    chmod 0755 $lxc_path
 }
 
 usage_err() {

src/lxc/lxc-setuid.in

@@ -25,6 +25,8 @@
 # When the capabilities are set, a non root user can manage the containers.
 #
 
+. @DATADIR@/lxc/lxc.functions
+
 usage() {
     echo "usage: $(basename $0) [-d]" >&2
 }
@@ -49,33 +51,33 @@ setuid()
 
 lxc_setuid()
 {
-    setuid @BINDIR@/lxc-attach
-    setuid @BINDIR@/lxc-create
-    setuid @BINDIR@/lxc-execute
-    setuid @BINDIR@/lxc-start
-    setuid @BINDIR@/lxc-restart
-    setuid @BINDIR@/lxc-unshare
-    setuid @BINDIR@/lxc-netstat
-    setuid @BINDIR@/lxc-checkpoint
-    setuid @LXCINITDIR@/lxc-init
+    setuid $bindir/lxc-attach
+    setuid $bindir/lxc-create
+    setuid $bindir/lxc-execute
+    setuid $bindir/lxc-start
+    setuid $bindir/lxc-restart
+    setuid $bindir/lxc-unshare
+    setuid $bindir/lxc-netstat
+    setuid $bindir/lxc-checkpoint
+    setuid $lxcinitdir/lxc-init
 
-    test -e @LXCPATH@ || mkdir -p @LXCPATH@
-    chmod 0777 @LXCPATH@
+    test -e $lxc_path || mkdir -p $lxc_path
+    chmod 0777 $lxc_path
 }
 
 lxc_dropuid()
 {
-    setuid -r @BINDIR@/lxc-attach
-    setuid -r @BINDIR@/lxc-create
-    setuid -r @BINDIR@/lxc-execute
-    setuid -r @BINDIR@/lxc-start
-    setuid -r @BINDIR@/lxc-restart
-    setuid -r @BINDIR@/lxc-unshare
-    setuid -r @BINDIR@/lxc-netstat
-    setuid -r @BINDIR@/lxc-checkpoint
-    setuid -r @LXCINITDIR@/lxc-init
+    setuid -r $bindir/lxc-attach
+    setuid -r $bindir/lxc-create
+    setuid -r $bindir/lxc-execute
+    setuid -r $bindir/lxc-start
+    setuid -r $bindir/lxc-restart
+    setuid -r $bindir/lxc-unshare
+    setuid -r $bindir/lxc-netstat
+    setuid -r $bindir/lxc-checkpoint
+    setuid -r $lxcinitdir/lxc-init
 
-    chmod 0755 @LXCPATH@
+    chmod 0755 $lxc_path
 }
 
 usage_err() {

src/lxc/lxc.functions.in

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+#
+# lxc: linux Container library
+
+# Authors:
+# Serge Hallyn <serge.hallyn@ubuntu.com>
+
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+# This file contains helpers for the various lxc shell scripts
+
+globalconf=@LXC_GLOBAL_CONF@
+bindir=@BINDIR@
+templatedir=@LXCTEMPLATEDIR@
+lxcinitdir=@LXCINITDIR@
+
+get_default_lxcpath() {
+        (grep -v "^#" "$globalconf" 2>/dev/null || echo "lxcpath=@LXCPATH@") | \
+                grep "[ \t]*lxcpath[ \t]*=" | awk -F= '{ print $2 }'
+}
+
+lxc_path=`get_default_lxcpath`

src/lxc/lxc_execute.c

@@ -39,6 +39,7 @@
 #include "arguments.h"
 #include "config.h"
 #include "start.h"
+#include "utils.h"
 
 lxc_log_define(lxc_execute_ui, lxc_execute);
 
@@ -108,8 +109,14 @@ int main(int argc, char *argv[])
 		rcfile = (char *)my_args.rcfile;
 	else {
 		int rc;
+		char *lxcpath = default_lxc_path();
+		if (!lxcpath) {
+			ERROR("Out of memory");
+			return -1;
+		}
 
-		rc = asprintf(&rcfile, LXCPATH "/%s/config", my_args.name);
+		rc = asprintf(&rcfile, "%s/%s/config", lxcpath, my_args.name);
+		free(lxcpath);
 		if (rc == -1) {
 			SYSERROR("failed to allocate memory");
 			return -1;

src/lxc/lxc_restart.c

@@ -36,6 +36,7 @@
 #include "config.h"
 #include "confile.h"
 #include "arguments.h"
+#include "utils.h"
 
 lxc_log_define(lxc_restart_ui, lxc_restart);
 
@@ -131,8 +132,14 @@ int main(int argc, char *argv[])
 		rcfile = (char *)my_args.rcfile;
 	else {
 		int rc;
+		char *lxcpath = default_lxc_path();
+		if (!lxcpath) {
+			ERROR("Out of memory");
+			return -1;
+		}
 
-		rc = asprintf(&rcfile, LXCPATH "/%s/config", my_args.name);
+		rc = asprintf(&rcfile, "%s/%s/config", lxcpath, my_args.name);
+		free(lxcpath);
 		if (rc == -1) {
 			SYSERROR("failed to allocate memory");
 			return -1;

src/lxc/lxc_start.c

@@ -173,8 +173,15 @@ int main(int argc, char *argv[])
 		rcfile = (char *)my_args.rcfile;
 	else {
 		int rc;
+		char *lxcpath = default_lxc_path();
+		if (!lxcpath) {
+			ERROR("Out of memory");
+			return -1;
+		}
 
-		rc = asprintf(&rcfile, LXCPATH "/%s/config", my_args.name);
+		rc = asprintf(&rcfile, "%s/%s/config", lxcpath, my_args.name);
+		INFO("using rcfile %s", rcfile);
+		free(lxcpath);
 		if (rc == -1) {
 			SYSERROR("failed to allocate memory");
 			return err;

src/lxc/lxccontainer.c

@@ -30,6 +30,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <errno.h>
+#include <lxc/utils.h>
 
 lxc_log_define(lxc_container, lxc);
 
@@ -82,6 +83,10 @@ static void lxc_container_free(struct lxc_container *c)
 		lxc_conf_free(c->lxc_conf);
 		c->lxc_conf = NULL;
 	}
+	if (c->config_path) {
+		free(c->config_path);
+		c->config_path = NULL;
+	}
 	free(c);
 }
 
@@ -483,11 +488,11 @@ static bool create_container_dir(struct lxc_container *c)
 	char *s;
 	int len, ret;
 
-	len = strlen(LXCPATH) + strlen(c->name) + 2;
+	len = strlen(c->config_path) + strlen(c->name) + 2;
 	s = malloc(len);
 	if (!s)
 		return false;
-	ret = snprintf(s, len, "%s/%s", LXCPATH, c->name);
+	ret = snprintf(s, len, "%s/%s", c->config_path, c->name);
 	if (ret < 0 || ret >= len) {
 		free(s);
 		return false;
@@ -577,11 +582,11 @@ static bool lxcapi_create(struct lxc_container *c, char *t, char *const argv[])
 			exit(1);
 		newargv[0] = t;
 
-		len = strlen(LXCPATH) + strlen(c->name) + strlen("--path=") + 2;
+		len = strlen(c->config_path) + strlen(c->name) + strlen("--path=") + 2;
 		patharg = malloc(len);
 		if (!patharg)
 			exit(1);
-		ret = snprintf(patharg, len, "--path=%s/%s", LXCPATH, c->name);
+		ret = snprintf(patharg, len, "--path=%s/%s", c->config_path, c->name);
 		if (ret < 0 || ret >= len)
 			exit(1);
 		newargv[1] = patharg;
@@ -859,6 +864,37 @@ static char *lxcapi_config_file_name(struct lxc_container *c)
 	return strdup(c->configfile);
 }
 
+static const char *lxcapi_get_config_path(struct lxc_container *c)
+{
+	if (!c || !c->config_path)
+		return NULL;
+	return (const char *)(c->config_path);
+}
+
+static bool lxcapi_set_config_path(struct lxc_container *c, const char *path)
+{
+	char *p;
+	bool b = false;
+
+	if (!c)
+		return b;
+
+	if (lxclock(c->privlock, 0))
+		return b;
+
+	p = strdup(path);
+	if (!p)
+		goto err;
+	b = true;
+	if (c->config_path)
+		free(c->config_path);
+	c->config_path = p;
+err:
+	lxcunlock(c->privlock);
+	return b;
+}
+
+
 static bool lxcapi_set_cgroup_item(struct lxc_container *c, const char *subsys, const char *value)
 {
 	int ret;
@@ -914,6 +950,12 @@ struct lxc_container *lxc_container_new(const char *name)
 	}
 	memset(c, 0, sizeof(*c));
 
+	c->config_path = default_lxc_path();
+	if (!c->config_path) {
+		fprintf(stderr, "Out of memory");
+		goto err;
+	}
+
 	c->name = malloc(strlen(name)+1);
 	if (!c->name) {
 		fprintf(stderr, "Error allocating lxc_container name\n");
@@ -934,13 +976,13 @@ struct lxc_container *lxc_container_new(const char *name)
 		goto err;
 	}
 
-	len = strlen(LXCPATH)+strlen(c->name)+strlen("/config")+2;
+	len = strlen(c->config_path)+strlen(c->name)+strlen("/config")+2;
 	c->configfile = malloc(len);
 	if (!c->configfile) {
 		fprintf(stderr, "Error allocating config file pathname\n");
 		goto err;
 	}
-	ret = snprintf(c->configfile, len, "%s/%s/config", LXCPATH, c->name);
+	ret = snprintf(c->configfile, len, "%s/%s/config", c->config_path, c->name);
 	if (ret < 0 || ret >= len) {
 		fprintf(stderr, "Error printing out config file name\n");
 		goto err;
@@ -974,6 +1016,8 @@ struct lxc_container *lxc_container_new(const char *name)
 	c->get_config_item = lxcapi_get_config_item;
 	c->get_cgroup_item = lxcapi_get_cgroup_item;
 	c->set_cgroup_item = lxcapi_set_cgroup_item;
+	c->get_config_path = lxcapi_get_config_path;
+	c->set_config_path = lxcapi_set_config_path;
 
 	/* we'll allow the caller to update these later */
 	if (lxc_log_init(NULL, "none", NULL, "lxc_container", 0)) {
@@ -981,10 +1025,6 @@ struct lxc_container *lxc_container_new(const char *name)
 		goto err;
 	}
 
-	/*
-	 * default configuration file is $LXCPATH/$NAME/config
-	 */
-
 	return c;
 
 err:

src/lxc/lxccontainer.h

@@ -18,6 +18,8 @@ struct lxc_container {
 	int error_num;
 	int daemonize;
 
+	char *config_path;
+
 	bool (*is_defined)(struct lxc_container *c);  // did /var/lib/lxc/$name/config exist
 	const char *(*state)(struct lxc_container *c);
 	bool (*is_running)(struct lxc_container *c);  // true so long as defined and not stopped
@@ -58,6 +60,18 @@ struct lxc_container {
 	int (*get_cgroup_item)(struct lxc_container *c, const char *subsys, char *retv, int inlen);
 	bool (*set_cgroup_item)(struct lxc_container *c, const char *subsys, const char *value);
 
+	/*
+	 * Each container can have a custom configuration path.  However
+	 * by default it will be set to either the LXCPATH configure
+	 * variable, or the lxcpath value in the LXC_GLOBAL_CONF configuration
+	 * file (i.e. /etc/lxc/lxc.conf).
+	 * You can change the value for a specific container with
+	 * set_config_path().  Note there is no other way to specify this in
+	 * general at the moment.
+	 */
+	const char *(*get_config_path)(struct lxc_container *c);
+	bool (*set_config_path)(struct lxc_container *c, const char *path);
+
 #if 0
 	bool (*commit_cgroups)(struct lxc_container *c);
 	bool (*reread_cgroups)(struct lxc_container *c);

src/lxc/utils.c

@@ -193,3 +193,59 @@ extern int mkdir_p(char *dir, mode_t mode)
 
         return 0;
 }
+
+static char *copypath(char *p)
+{
+	int len = strlen(p);
+	char *retbuf;
+
+	if (len < 1)
+		return NULL;
+	if (p[len-1] == '\n') {
+		p[len-1] = '\0';
+		len--;
+	}
+	retbuf = malloc(len+1);
+	if (!retbuf)
+		return NULL;
+	strcpy(retbuf, p);
+	return retbuf;
+}
+
+char *default_lxc_path(void)
+{
+	char buf[1024], *p, *retbuf;
+	FILE *fin;
+
+	fin = fopen(LXC_GLOBAL_CONF, "r");
+	if (fin) {
+		while (fgets(buf, 1024, fin)) {
+			if (buf[0] == '#')
+				continue;
+			p = strstr(buf, "lxcpath");
+			if (!p)
+				continue;
+			p = strchr(p, '=');
+			if (!p)
+				continue;
+			p++;
+			while (*p && (*p == ' ' || *p == '\t')) p++;
+			if (!*p)
+				continue;
+			retbuf = copypath(p);
+			goto out;
+		}
+	}
+	/* we couldn't open the file, or didn't find a lxcpath
+	 * entry there.  Return @LXCPATH@ */
+	retbuf = malloc(strlen(LXCPATH)+1);
+	if (!retbuf)
+		goto out;
+	strcpy(retbuf, LXCPATH);
+
+out:
+	if (fin)
+		fclose(fin);
+	INFO("returning %s", (retbuf ? retbuf : "null"));
+	return retbuf;
+}

src/lxc/utils.h

@@ -27,5 +27,10 @@ extern int lxc_copy_file(const char *src, const char *dst);
 extern int lxc_setup_fs(void);
 extern int get_u16(unsigned short *val, const char *arg, int base);
 extern int mkdir_p(const char *dir, mode_t mode);
+/*
+ * Return a newly allocated buffer containing the default container
+ * path.  Caller must free this buffer.
+ */
+extern char *default_lxc_path(void);
 
 #endif

src/tests/Makefile.am

@@ -19,6 +19,7 @@ lxc_test_getkeys_SOURCES = getkeys.c
 AM_CFLAGS=-I$(top_srcdir)/src \
 	-DLXCROOTFSMOUNT=\"$(LXCROOTFSMOUNT)\" \
 	-DLXCPATH=\"$(LXCPATH)\" \
+	-DLXC_GLOBAL_CONF=\"$(LXC_GLOBAL_CONF)\" \
 	-DLXCINITDIR=\"$(LXCINITDIR)\"
 
 bin_PROGRAMS = lxc-test-containertests lxc-test-locktests lxc-test-startone \