Initial support for cgmanager

This patch splits out most of the cgroupfs-specific code, so that
cgroup-manager versions can be plugged in.  The case I did
not handle is cgroup_enter at lxc_attach.  I'm hoping that case can
be greatly simplified, but will worry about it after fleshing out the
cgroup manager handlers.

This also simplify the freezer functions.

This seems to not regress my common tests when running without
cgmanager, but I'd like to do a bit more testing before pushing.
However I was hoping to get some more eyes on this so am sending it
out now.

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

configure.ac

@@ -240,6 +240,23 @@ AM_COND_IF([ENABLE_SECCOMP],
 		])
 	])
 
+# cgmanager
+AC_ARG_ENABLE([cgmanager],
+	[AC_HELP_STRING([--enable-cgmanager], [enable cgmanager support [default=auto]])],
+	[], [enable_cgmanager=auto])
+
+if test "x$enable_cgmanager" = "xauto" ; then
+	AC_CHECK_LIB([cgmanager],[cgmanager_create],[enable_cgmanager=yes],[enable_cgmanager=no])
+fi
+AM_CONDITIONAL([ENABLE_CGMANAGER], [test "x$enable_cgmanager" = "xyes"])
+
+AM_COND_IF([ENABLE_CGMANAGER],
+	[PKG_CHECK_MODULES([CGMANAGER], [libcgmanager])
+	PKG_CHECK_MODULES([NIH], [libnih >= 1.0.2])
+	PKG_CHECK_MODULES([NIH_DBUS], [libnih-dbus >= 1.0.0])
+	PKG_CHECK_MODULES([DBUS], [dbus-1 >= 1.2.16])
+	])
+
 # Linux capabilities
 AC_ARG_ENABLE([capabilities],
 	[AC_HELP_STRING([--enable-capabilities], [enable kernel capabilities support [default=auto]])],
@@ -689,6 +706,7 @@ Security features:
  - Linux capabilities: $enable_capabilities
  - seccomp: $enable_seccomp
  - SELinux: $enable_selinux
+ - cgmanager: $enable_cgmanager
 
 Bindings:
  - lua: $enable_lua

src/lxc/Makefile.am

@@ -93,6 +93,10 @@ liblxc_so_SOURCES = \
 	\
 	$(LSM_SOURCES)
 
+if ENABLE_CGMANAGER
+liblxc_so_SOURCES += cgmanager.c
+endif
+
 if IS_BIONIC
 liblxc_so_SOURCES += \
 	../include/ifaddrs.c ../include/ifaddrs.h \
@@ -122,6 +126,10 @@ if ENABLE_APPARMOR
 AM_CFLAGS += -DHAVE_APPARMOR
 endif
 
+if ENABLE_CGMANAGER
+AM_CFLAGS += -DHAVE_CGMANAGER
+endif
+
 if ENABLE_SELINUX
 AM_CFLAGS += -DHAVE_SELINUX
 endif
@@ -144,6 +152,11 @@ liblxc_so_LDFLAGS = \
 
 liblxc_so_LDADD = $(CAP_LIBS) $(APPARMOR_LIBS) $(SECCOMP_LIBS)
 
+#if ENABLE_CGMANAGER
+liblxc_so_LDADD += $(CGMANAGER_LIBS) $(DBUS_LIBS) $(NIH_LIBS) $(NIH_DBUS_LIBS)
+liblxc_so_CFLAGS += $(CGMANAGER_CFLAGS) $(DBUS_CFLAGS) $(NIH_CFLAGS) $(NIH_DBUS_CFLAGS)
+#endif
+
 bin_SCRIPTS = \
 	lxc-ps \
 	lxc-netstat \
@@ -245,6 +258,11 @@ LDADD=liblxc.so @CAP_LIBS@ @APPARMOR_LIBS@ @SECCOMP_LIBS@
 lxc_attach_SOURCES = lxc_attach.c
 lxc_autostart_SOURCES = lxc_autostart.c
 lxc_cgroup_SOURCES = lxc_cgroup.c
+#if ENABLE_CGMANAGER
+lxc_cgroup_SOURCES += cgmanager.c
+lxc_cgroup_LDADD = $(CGMANAGER_LIBS) $(DBUS_LIBS) $(NIH_LIBS) $(NIH_DBUS_LIBS) $(LDADD)
+lxc_cgroup_CFLAGS = $(CGMANAGER_CFLAGS) $(DBUS_CFLAGS) $(NIH_CFLAGS) $(NIH_DBUS_CFLAGS)
+#endif
 lxc_checkpoint_SOURCES = lxc_checkpoint.c
 lxc_config_SOURCES = lxc_config.c
 lxc_console_SOURCES = lxc_console.c

src/lxc/attach.c

@@ -748,7 +748,11 @@ int lxc_attach(const char* name, const char* lxcpath, lxc_attach_exec_t exec_fun
 				goto cleanup_error;
 			}
 
-			ret = lxc_cgroup_enter(container_info, attached_pid, false);
+			/*
+			 * TODO - switch over to using a cgroup_operation.  We can't use
+			 * cgroup_enter() as that takes a handler.
+			 */
+			ret = lxc_cgroupfs_enter(container_info, attached_pid, false);
 			lxc_cgroup_process_info_free(container_info);
 			if (ret < 0) {
 				ERROR("could not move attached process %ld to cgroup of container", (long)attached_pid);