Introduce basic infrastructure for virtlockd daemon

The virtlockd daemon will maintain locks on behalf of libvirtd.
There are two reasons for it to be separate

 - Avoid risk of other libvirtd threads accidentally
   releasing fcntl() locks by opening + closing a file
   that is locked
 - Ensure locks can be preserved across libvirtd restarts.
   virtlockd will need to be able to re-exec itself while
   maintaining locks. This is simpler to achieve if its
   sole job is maintaining locks
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

.gitignore

@@ -123,6 +123,8 @@
 /src/test_libvirt*.aug
 /src/util/virkeymaps.h
 /src/virt-aa-helper
+/src/virtlockd
+/src/virtlockd.init
 /tests/*.log
 /tests/*.pid
 /tests/*xml2*test

cfg.mk

@@ -655,6 +655,8 @@ sc_prohibit_cross_inclusion:
 	@for dir in $(cross_dirs); do					\
 	  case $$dir in							\
 	    util/) safe="util";;					\
+	    locking/)							\
+	      safe="($$dir|util|conf|rpc)";;				\
 	    cpu/ | locking/ | network/ | rpc/ | security/)		\
 	      safe="($$dir|util|conf)";;				\
 	    xenapi/ | xenxs/ ) safe="($$dir|util|conf|xen)";;		\
@@ -743,7 +745,7 @@ $(srcdir)/src/remote/remote_client_bodies.h: $(srcdir)/src/remote/remote_protoco
 # List all syntax-check exemptions:
 exclude_file_name_regexp--sc_avoid_strcase = ^tools/virsh\.h$$
 
-_src1=libvirt|fdstream|qemu/qemu_monitor|util/(command|util)|xen/xend_internal|rpc/virnetsocket|lxc/lxc_controller
+_src1=libvirt|fdstream|qemu/qemu_monitor|util/(command|util)|xen/xend_internal|rpc/virnetsocket|lxc/lxc_controller|locking/lock_daemon
 exclude_file_name_regexp--sc_avoid_write = \
   ^(src/($(_src1))|daemon/libvirtd|tools/console|tests/(shunload|virnettlscontext)test)\.c$$
 
@@ -776,7 +778,7 @@ exclude_file_name_regexp--sc_prohibit_close = \
 exclude_file_name_regexp--sc_prohibit_empty_lines_at_EOF = \
   (^tests/(qemuhelp|nodeinfo)data/|\.(gif|ico|png|diff)$$)
 
-_src2=src/(util/command|libvirt|lxc/lxc_controller)
+_src2=src/(util/command|libvirt|lxc/lxc_controller|locking/lock_daemon)
 exclude_file_name_regexp--sc_prohibit_fork_wrappers = \
   (^($(_src2)|tests/testutils|daemon/libvirtd)\.c$$)
 

libvirt.spec.in

@@ -1662,9 +1662,11 @@ fi
 %else
 %{_sysconfdir}/rc.d/init.d/libvirtd
 %{_sysconfdir}/rc.d/init.d/libvirt-guests
+%{_sysconfdir}/rc.d/init.d/virtlockd
 %endif
 %doc daemon/libvirtd.upstart
 %config(noreplace) %{_sysconfdir}/sysconfig/libvirtd
+%config(noreplace) %{_sysconfdir}/sysconfig/virtlockd
 %config(noreplace) %{_sysconfdir}/libvirt/libvirtd.conf
 %if 0%{?fedora} >= 14 || 0%{?rhel} >= 6
 %config(noreplace) %{_sysconfdir}/sysctl.d/libvirtd
@@ -1731,6 +1733,10 @@ rm -f $RPM_BUILD_ROOT%{_sysconfdir}/sysctl.d/libvirtd
 %dir %attr(0755, root, root) %{_localstatedir}/lib/libvirt/dnsmasq/
 %endif
 
+%if %{with_libvirtd}
+%dir %attr(0755, root, root) %{_libdir}/libvirt/lock-driver
+%endif
+
 %if %{with_qemu}
 %{_datadir}/augeas/lenses/libvirtd_qemu.aug
 %{_datadir}/augeas/lenses/tests/test_libvirtd_qemu.aug
@@ -1764,6 +1770,7 @@ rm -f $RPM_BUILD_ROOT%{_sysconfdir}/sysctl.d/libvirtd
 
 %attr(0755, root, root) %{_libexecdir}/libvirt_iohelper
 %attr(0755, root, root) %{_sbindir}/libvirtd
+%attr(0755, root, root) %{_sbindir}/virtlockd
 
 %{_mandir}/man8/libvirtd.8*
 

po/POTFILES.in

@@ -48,6 +48,8 @@ src/interface/interface_backend_udev.c
 src/internal.h
 src/libvirt.c
 src/libvirt-qemu.c
+src/locking/lock_daemon.c
+src/locking/lock_daemon_config.c
 src/locking/lock_driver_sanlock.c
 src/locking/lock_manager.c
 src/locking/sanlock_helper.c

src/Makefile.am

@@ -148,6 +148,13 @@ LOCK_DRIVER_SANLOCK_SOURCES = \
 LOCK_DRIVER_SANLOCK_HELPER_SOURCES = \
 		locking/sanlock_helper.c
 
+LOCK_DAEMON_SOURCES = \
+		locking/lock_daemon.h \
+		locking/lock_daemon.c \
+		locking/lock_daemon_config.h \
+		locking/lock_daemon_config.c \
+		$(NULL)
+
 NETDEV_CONF_SOURCES =						\
 		conf/netdev_bandwidth_conf.h conf/netdev_bandwidth_conf.c \
 		conf/netdev_vport_profile_conf.h conf/netdev_vport_profile_conf.c \
@@ -1510,6 +1517,76 @@ libvirt_qemu_la_CFLAGS = $(AM_CFLAGS)
 libvirt_qemu_la_LIBADD = libvirt.la $(CYGWIN_EXTRA_LIBADD)
 EXTRA_DIST += $(LIBVIRT_QEMU_SYMBOL_FILE)
 
+if WITH_LIBVIRTD
+sbin_PROGRAMS = virtlockd
+
+virtlockd_SOURCES = $(LOCK_DAEMON_SOURCES)
+virtlockd_CFLAGS = \
+		$(AM_CFLAGS) \
+		$(NULL)
+virtlockd_LDFLAGS = \
+		$(AM_LDFLAGS) \
+		$(CYGWIN_EXTRA_LDFLAGS) \
+		$(MINGW_EXTRA_LDFLAGS) \
+		$(NULL)
+virtlockd_LDADD = \
+		libvirt-net-rpc-server.la \
+		libvirt-net-rpc.la \
+		libvirt_util.la \
+		../gnulib/lib/libgnu.la \
+		$(CYGWIN_EXTRA_LIBADD) \
+		$(NULL)
+if WITH_DTRACE_PROBES
+virtlockd_LDADD += libvirt_probes.lo
+endif
+
+else
+EXTRA_DIST += $(LOCK_DAEMON_SOURCES)
+endif
+
+EXTRA_DIST += locking/virtlockd.sysconf
+
+install-sysconfig:
+	mkdir -p $(DESTDIR)$(sysconfdir)/sysconfig
+	$(INSTALL_DATA) $(srcdir)/locking/virtlockd.sysconf \
+	  $(DESTDIR)$(sysconfdir)/sysconfig/virtlockd
+
+uninstall-sysconfig:
+	rm -f $(DESTDIR)$(sysconfdir)/sysconfig/virtlockd
+
+EXTRA_DIST += locking/virtlockd.init.in
+
+if WITH_LIBVIRTD
+if LIBVIRT_INIT_SCRIPT_RED_HAT
+install-init:: virtlockd.init install-sysconfig
+	mkdir -p $(DESTDIR)$(sysconfdir)/rc.d/init.d
+	$(INSTALL_SCRIPT) virtlockd.init \
+	  $(DESTDIR)$(sysconfdir)/rc.d/init.d/virtlockd
+
+uninstall-init:: uninstall-sysconfig
+	rm -f $(DESTDIR)$(sysconfdir)/rc.d/init.d/libvirtd
+
+BUILT_SOURCES += virtlockd.init
+else
+install-init::
+uninstall-init::
+endif
+else
+install-init::
+uninstall-init::
+endif
+
+virtlockd.init: locking/virtlockd.init.in $(top_builddir)/config.status
+	$(AM_V_GEN)sed					\
+	    -e "s!::localstatedir::!$(localstatedir)!g"	\
+	    -e "s!::sbindir::!$(sbindir)!g"		\
+	    -e "s!::sysconfdir::!$(sysconfdir)!g"	\
+	    < $< > $@-t &&				\
+	    chmod a+x $@-t &&				\
+	    mv $@-t $@
+
+
+
 if HAVE_SANLOCK
 lockdriverdir = $(libdir)/libvirt/lock-driver
 lockdriver_LTLIBRARIES = sanlock.la
@@ -1747,7 +1824,11 @@ endif
 endif
 EXTRA_DIST += $(SECURITY_DRIVER_APPARMOR_HELPER_SOURCES)
 
-install-data-local:
+install-data-local: install-init
+if WITH_LIBVIRTD
+	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/lockd"
+	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/run/libvirt/lockd"
+endif
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/cache/libvirt"
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/images"
 	$(MKDIR_P) "$(DESTDIR)$(localstatedir)/lib/libvirt/filesystems"
@@ -1796,7 +1877,11 @@ if WITH_NETWORK
 	    $(DESTDIR)$(sysconfdir)/libvirt/qemu/networks/autostart/default.xml
 endif
 
-uninstall-local::
+uninstall-local:: uninstall-init
+if WITH_LIBVIRTD
+	rmdir "$(DESTDIR)$(localstatedir)/lib/libvirt/lockd" ||:
+	rmdir "$(DESTDIR)$(localstatedir)/run/libvirt/lockd" ||:
+endif
 	rmdir "$(DESTDIR)$(localstatedir)/cache/libvirt" ||:
 	rmdir "$(DESTDIR)$(localstatedir)/lib/libvirt/images" ||:
 	rmdir "$(DESTDIR)$(localstatedir)/lib/libvirt/filesystems" ||:

src/locking/lock_daemon.h

+/*
+ * lock_daemon.h: lock management daemon
+ *
+ * Copyright (C) 2006-2012 Red Hat, Inc.
+ *
+ * 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, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Daniel P. Berrange <berrange@redhat.com>
+ */
+
+#ifndef __VIR_LOCK_DAEMON_H__
+# define __VIR_LOCK_DAEMON_H__
+
+# include "virlockspace.h"
+# include "threads.h"
+
+typedef struct _virLockDaemon virLockDaemon;
+typedef virLockDaemon *virLockDaemonPtr;
+
+typedef struct _virLockDaemonClient virLockDaemonClient;
+typedef virLockDaemonClient *virLockDaemonClientPtr;
+
+struct _virLockDaemonClient {
+    virMutex lock;
+
+    pid_t clientPid;
+};
+
+extern virLockDaemonPtr lockDaemon;
+
+#endif /* __VIR_LOCK_DAEMON_H__ */

src/locking/lock_daemon_config.c

+/*
+ * lock_daemon_config.h: virtlockd config file handling
+ *
+ * Copyright (C) 2006-2012 Red Hat, Inc.
+ * Copyright (C) 2006 Daniel P. Berrange
+ *
+ * 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, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Daniel P. Berrange <berrange@redhat.com>
+ */
+
+#include <config.h>
+
+#include "lock_daemon_config.h"
+#include "conf.h"
+#include "memory.h"
+#include "virterror_internal.h"
+#include "logging.h"
+#include "rpc/virnetserver.h"
+#include "configmake.h"
+
+#define VIR_FROM_THIS VIR_FROM_CONF
+
+
+/* A helper function used by each of the following macros.  */
+static int
+checkType(virConfValuePtr p, const char *filename,
+          const char *key, virConfType required_type)
+{
+    if (p->type != required_type) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("remoteReadConfigFile: %s: %s: invalid type:"
+                         " got %s; expected %s"), filename, key,
+                       virConfTypeName(p->type),
+                       virConfTypeName(required_type));
+        return -1;
+    }
+    return 0;
+}
+
+/* If there is no config data for the key, #var_name, then do nothing.
+   If there is valid data of type VIR_CONF_STRING, and strdup succeeds,
+   store the result in var_name.  Otherwise, (i.e. invalid type, or strdup
+   failure), give a diagnostic and "goto" the cleanup-and-fail label.  */
+#define GET_CONF_STR(conf, filename, var_name)                          \
+    do {                                                                \
+        virConfValuePtr p = virConfGetValue(conf, #var_name);           \
+        if (p) {                                                        \
+            if (checkType(p, filename, #var_name, VIR_CONF_STRING) < 0) \
+                goto error;                                             \
+            VIR_FREE(data->var_name);                                   \
+            if (!(data->var_name = strdup(p->str))) {                   \
+                virReportOOMError();                                    \
+                goto error;                                             \
+            }                                                           \
+        }                                                               \
+    } while (0)
+
+/* Like GET_CONF_STR, but for integral values.  */
+#define GET_CONF_INT(conf, filename, var_name)                          \
+    do {                                                                \
+        virConfValuePtr p = virConfGetValue(conf, #var_name);           \
+        if (p) {                                                        \
+            if (checkType(p, filename, #var_name, VIR_CONF_LONG) < 0)   \
+                goto error;                                             \
+            data->var_name = p->l;                                      \
+        }                                                               \
+    } while (0)
+
+int
+virLockDaemonConfigFilePath(bool privileged, char **configfile)
+{
+    if (privileged) {
+        if (!(*configfile = strdup(SYSCONFDIR "/libvirt/virtlockd.conf")))
+            goto no_memory;
+    } else {
+        char *configdir = NULL;
+
+        if (!(configdir = virGetUserConfigDirectory()))
+            goto error;
+
+        if (virAsprintf(configfile, "%s/virtlockd.conf", configdir) < 0) {
+            VIR_FREE(configdir);
+            goto no_memory;
+        }
+        VIR_FREE(configdir);
+    }
+
+    return 0;
+
+no_memory:
+    virReportOOMError();
+error:
+    return -1;
+}
+
+
+virLockDaemonConfigPtr
+virLockDaemonConfigNew(bool privileged ATTRIBUTE_UNUSED)
+{
+    virLockDaemonConfigPtr data;
+
+    if (VIR_ALLOC(data) < 0) {
+        virReportOOMError();
+        return NULL;
+    }
+
+    data->log_buffer_size = 64;
+
+    return data;
+}
+
+void
+virLockDaemonConfigFree(virLockDaemonConfigPtr data)
+{
+    if (!data)
+        return;
+
+    VIR_FREE(data->log_filters);
+    VIR_FREE(data->log_outputs);
+
+    VIR_FREE(data);
+}
+
+static int
+virLockDaemonConfigLoadOptions(virLockDaemonConfigPtr data,
+                               const char *filename,
+                               virConfPtr conf)
+{
+    GET_CONF_INT(conf, filename, log_level);
+    GET_CONF_STR(conf, filename, log_filters);
+    GET_CONF_STR(conf, filename, log_outputs);
+    GET_CONF_INT(conf, filename, log_buffer_size);
+
+    return 0;
+
+error:
+    return -1;
+}
+
+
+/* Read the config file if it exists.
+ * Only used in the remote case, hence the name.
+ */
+int
+virLockDaemonConfigLoadFile(virLockDaemonConfigPtr data,
+                            const char *filename,
+                            bool allow_missing)
+{
+    virConfPtr conf;
+    int ret;
+
+    if (allow_missing &&
+        access(filename, R_OK) == -1 &&
+        errno == ENOENT)
+        return 0;
+
+    conf = virConfReadFile(filename, 0);
+    if (!conf)
+        return -1;
+
+    ret = virLockDaemonConfigLoadOptions(data, filename, conf);
+    virConfFree(conf);
+    return ret;
+}
+
+int virLockDaemonConfigLoadData(virLockDaemonConfigPtr data,
+                                const char *filename,
+                                const char *filedata)
+{
+    virConfPtr conf;
+    int ret;
+
+    conf = virConfReadMem(filedata, strlen(filedata), 0);
+    if (!conf)
+        return -1;
+
+    ret = virLockDaemonConfigLoadOptions(data, filename, conf);
+    virConfFree(conf);
+    return ret;
+}

src/locking/lock_daemon_config.h

+/*
+ * lock_daemon_config.h: virtlockd config file handling
+ *
+ * Copyright (C) 2006-2012 Red Hat, Inc.
+ * Copyright (C) 2006 Daniel P. Berrange
+ *
+ * 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, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Daniel P. Berrange <berrange@redhat.com>
+ */
+
+#ifndef __VIR_LOCK_DAEMON_CONFIG_H__
+# define __VIR_LOCK_DAEMON_CONFIG_H__
+
+# include "internal.h"
+
+typedef struct _virLockDaemonConfig virLockDaemonConfig;
+typedef virLockDaemonConfig *virLockDaemonConfigPtr;
+
+struct _virLockDaemonConfig {
+    int log_level;
+    char *log_filters;
+    char *log_outputs;
+    int log_buffer_size;
+};
+
+
+int virLockDaemonConfigFilePath(bool privileged, char **configfile);
+virLockDaemonConfigPtr virLockDaemonConfigNew(bool privileged);
+void virLockDaemonConfigFree(virLockDaemonConfigPtr data);
+int virLockDaemonConfigLoadFile(virLockDaemonConfigPtr data,
+                                const char *filename,
+                         bool allow_missing);
+int virLockDaemonConfigLoadData(virLockDaemonConfigPtr data,
+                                const char *filename,
+                                const char *filedata);
+
+#endif /* __LIBVIRTD_CONFIG_H__ */

src/locking/virtlockd.init.in

+#!/bin/sh
+
+# the following is the LSB init header see
+# http://www.linux-foundation.org/spec//booksets/LSB-Core-generic/LSB-Core-generic.html#INITSCRCOMCONV
+#
+### BEGIN INIT INFO
+# Provides: virtlockd
+# Default-Start: 3 4 5
+# Short-Description: virtual machine lock manager
+# Description: This is a daemon for managing locks
+#              on virtual machine disk images
+### END INIT INFO
+
+# the following is chkconfig init header
+#
+# virtlockd:   virtual machine lock manager
+#
+# chkconfig: 345 97 03
+# description:  This is a daemon for managing locks \
+#               on virtual machine disk images
+#
+# processname: virtlockd
+# pidfile: ::localstatedir::/run/libvirt/virtlockd.pid
+#
+
+# Source function library.
+. ::sysconfdir::/rc.d/init.d/functions
+
+SERVICE=virtlockd
+PROCESS=virtlockd
+PIDFILE=::localstatedir::/run/libvirt/lockd/$SERVICE.pid
+
+VIRTLOCKD_ARGS=
+
+test -f ::sysconfdir::/sysconfig/virtlockd && . ::sysconfdir::/sysconfig/virtlockd
+
+RETVAL=0
+
+start() {
+    echo -n $"Starting $SERVICE daemon: "
+    daemon --pidfile $PIDFILE --check $SERVICE $PROCESS --daemon $VIRTLOCKD_ARGS
+    RETVAL=$?
+    echo
+    [ $RETVAL -eq 0 ] && touch ::localstatedir::/lock/subsys/$SERVICE
+}
+
+stop() {
+    echo -n $"Stopping $SERVICE daemon: "
+
+    killproc -p $PIDFILE $PROCESS
+    RETVAL=$?
+    echo
+    if [ $RETVAL -eq 0 ]; then
+        rm -f ::localstatedir::/lock/subsys/$SERVICE
+        rm -f $PIDFILE
+    fi
+}
+
+restart() {
+    stop
+    start
+}
+
+reload() {
+    echo -n $"Reloading $SERVICE configuration: "
+
+    killproc -p $PIDFILE $PROCESS -HUP
+    RETVAL=$?
+    echo
+    return $RETVAL
+}
+
+# See how we were called.
+case "$1" in
+    start|stop|restart|reload)
+        $1
+        ;;
+    status)
+        status -p $PIDFILE $PROCESS
+        RETVAL=$?
+        ;;
+    force-reload)
+        reload
+        ;;
+    condrestart|try-restart)
+        [ -f ::localstatedir::/lock/subsys/$SERVICE ] && restart || :
+        ;;
+    *)
+        echo $"Usage: $0 {start|stop|status|restart|condrestart|reload|force-reload|try-restart}"
+        exit 2
+        ;;
+esac
+exit $RETVAL

src/locking/virtlockd.sysconf

+#
+# Pass extra arguments to virtlockd
+#VIRTLOCKD_ARGS=