add experimental checkpoint and restart commands

src/lxc/Makefile.am

@@ -22,6 +22,8 @@ liblxc_la_SOURCES = \
 	monitor.c monitor.h \
 	kill.c \
 	freezer.c \
+	checkpoint.c \
+	restart.c \
 	version.c \
 	lxc_cgroup.c lxc_cgroup.h \
 	lxc.h \
@@ -57,6 +59,8 @@ bin_PROGRAMS = \
 	lxc-info \
 	lxc-unfreeze \
 	lxc-priority \
+	lxc-checkpoint \
+	lxc-restart \
 	lxc-version
 
 lxc_create_SOURCES = lxc_create.c lxc_config.c lxc_config.h
@@ -98,5 +102,11 @@ lxc_unfreeze_LDADD = liblxc.la
 lxc_priority_SOURCES = lxc_priority.c
 lxc_priority_LDADD = liblxc.la
 
+lxc_checkpoint_SOURCES = lxc_checkpoint.c
+lxc_checkpoint_LDADD = liblxc.la
+
+lxc_restart_SOURCES = lxc_restart.c
+lxc_restart_LDADD = liblxc.la
+
 lxc_version_SOURCES = lxc_version.c
 lxc_version_LDADD = liblxc.la

src/lxc/checkpoint.c

+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <dlezcano at fr.ibm.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
+ */
+#define _GNU_SOURCE
+#include <stdio.h>
+#undef _GNU_SOURCE
+#include <fcntl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+#include <sys/file.h>
+#include <netinet/in.h>
+#include <net/if.h>
+
+#include <lxc.h>
+
+
+#if __i386__
+#    define __NR_checkpoint 334
+#else
+#    error "Architecture not supported"
+#endif
+static inline long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
+{
+	return syscall(__NR_checkpoint, pid, fd, flags);
+}
+
+int lxc_checkpoint(const char *name, int cfd, unsigned long flags)
+{
+	char init[MAXPATHLEN];
+	char val[MAXPIDLEN];
+	int fd, lock, ret = -1;
+	size_t pid;
+
+	lock = lxc_get_lock(name);
+	if (lock > 0) {
+		lxc_log_error("'%s' is not running", name);
+		lxc_put_lock(lock);
+		return -1;
+	}
+
+	if (lock < 0) {
+		lxc_log_error("failed to acquire the lock on '%s':%s", 
+			      name, strerror(-lock));
+		return -1;
+	}
+
+	snprintf(init, MAXPATHLEN, LXCPATH "/%s/init", name);
+	fd = open(init, O_RDONLY);
+	if (fd < 0) {
+		lxc_log_syserror("failed to open init file for %s", name);
+		goto out_unlock;
+	}
+	
+	if (read(fd, val, sizeof(val)) < 0) {
+		lxc_log_syserror("failed to read %s", init);
+		goto out_close;
+	}
+
+	pid = atoi(val);
+
+	if (sys_checkpoint(pid, cfd, flags) < 0) {
+		lxc_log_syserror("failed to checkpoint %zd", pid);
+		goto out_close;
+	}
+
+	ret = 0;
+
+out_close:
+	close(fd);
+out_unlock:
+	lxc_put_lock(lock);
+	return ret;
+}

src/lxc/lxc.h

@@ -251,6 +251,24 @@ extern int lxc_cgroup_get_cpuset(const char *name, long *cpumask,
 extern int lxc_cgroup_get_cpu_usage(const char *name, long long *usage);
 
 /*
+ * Checkpoint a container previously frozen
+ * @name : the name of the container being checkpointed
+ * @fd : file descriptor on which the container is checkpointed
+ * @flags : checkpoint flags
+ * Returns 0 on success, < 0 otherwise
+ */
+extern int lxc_checkpoint(const char *name, int fd, unsigned long flags);
+
+/*
+ * Restart a container previously frozen
+ * @name : the name of the container being restarted
+ * @fd : file descriptor from which the container is restarted
+ * @flags : restart flags
+ * Returns 0 on success, < 0 otherwise
+ */
+extern int lxc_restart(const char *name, int fd, unsigned long flags);
+
+/*
  * Returns the version number of the library
  */
 extern const char const *lxc_version(void);

src/lxc/lxc_checkpoint.c

+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <dlezcano at fr.ibm.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
+ */
+#include <stdio.h>
+#include <libgen.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include <lxc.h>
+
+void usage(char *cmd)
+{
+	fprintf(stderr, "%s <command>\n", basename(cmd));
+	fprintf(stderr, "\t -n <name>   : name of the container\n");
+	_exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+	char opt;
+	char *name = NULL;
+	int nbargs = 0;
+
+	while ((opt = getopt(argc, argv, "n:")) != -1) {
+		switch (opt) {
+		case 'n':
+			name = optarg;
+			break;
+		}
+
+		nbargs++;
+	}
+
+	if (!name)
+		usage(argv[0]);
+
+	if (lxc_checkpoint(name, STDOUT_FILENO, 0)) {
+		fprintf(stderr, "failed to checkpoint %s\n", name);
+		return 1;
+	}
+
+	return 0;
+}

src/lxc/lxc_restart.c

+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <dlezcano at fr.ibm.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
+ */
+#include <stdio.h>
+#include <libgen.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include <lxc.h>
+
+void usage(char *cmd)
+{
+	fprintf(stderr, "%s <command>\n", basename(cmd));
+	fprintf(stderr, "\t -n <name>   : name of the container\n");
+	_exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+	char opt;
+	char *name = NULL;
+	int nbargs = 0;
+
+	while ((opt = getopt(argc, argv, "n:")) != -1) {
+		switch (opt) {
+		case 'n':
+			name = optarg;
+			break;
+		}
+
+		nbargs++;
+	}
+
+	if (!name)
+		usage(argv[0]);
+
+	if (lxc_restart(name, STDIN_FILENO, 0)) {
+		fprintf(stderr, "failed to checkpoint %s\n", name);
+		return 1;
+	}
+
+	return 0;
+}

src/lxc/restart.c

+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <dlezcano at fr.ibm.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
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#undef _GNU_SOURCE
+#include <string.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <errno.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/param.h>
+#include <sys/file.h>
+#include <sys/types.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#include <lxc/lxc.h>
+
+LXC_TTY_HANDLER(SIGINT);
+LXC_TTY_HANDLER(SIGQUIT);
+
+
+#if __i386__
+#    define __NR_restart 335
+#else
+#    error "Architecture not supported"
+#endif
+static inline long sys_restart(pid_t pid, int fd, unsigned long flags)
+{
+	return syscall(__NR_restart, pid, fd, flags);
+}
+
+int lxc_restart(const char *name, int cfd, unsigned long flags)
+{
+	char *init = NULL, *val = NULL;
+	int fd, lock, sv[2], sync = 0, err = -1;
+	pid_t pid;
+	int clone_flags;
+	
+	lock = lxc_get_lock(name);
+	if (!lock) {
+		lxc_log_error("'%s' is busy", name);
+		return -1;
+	}
+
+	if (lock < 0) {
+		lxc_log_error("failed to acquire lock on '%s':%s",
+			      name, strerror(-lock));
+		return -1;
+	}
+
+	fcntl(lock, F_SETFD, FD_CLOEXEC);
+
+	/* Begin the set the state to STARTING*/
+	if (lxc_setstate(name, STARTING)) {
+		lxc_log_error("failed to set state %s", lxc_state2str(STARTING));
+		goto out;
+	}
+
+	/* Synchro socketpair */
+	if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sv)) {
+		lxc_log_syserror("failed to create communication socketpair");
+		goto err;
+	}
+
+	/* Avoid signals from terminal */
+	LXC_TTY_ADD_HANDLER(SIGINT);
+	LXC_TTY_ADD_HANDLER(SIGQUIT);
+
+	clone_flags = CLONE_NEWPID|CLONE_NEWIPC;
+	if (conf_has_fstab(name))
+		clone_flags |= CLONE_NEWNS;
+	if (conf_has_utsname(name))
+		clone_flags |= CLONE_NEWUTS;
+	if (conf_has_network(name))
+		clone_flags |= CLONE_NEWNET;
+
+	/* Create a process in a new set of namespaces */
+	pid = fork_ns(clone_flags);
+	if (pid < 0) {
+		lxc_log_syserror("failed to fork into a new namespace");
+		goto err_fork_ns;
+	}
+
+	if (!pid) {
+
+		close(sv[1]);
+
+		/* Be sure we don't inherit this after the exec */
+		fcntl(sv[0], F_SETFD, FD_CLOEXEC);
+		
+		/* Tell our father he can begin to configure the container */
+		if (write(sv[0], &sync, sizeof(sync)) < 0) {
+			lxc_log_syserror("failed to write socket");
+			return 1;
+		}
+
+		/* Wait for the father to finish the configuration */
+		if (read(sv[0], &sync, sizeof(sync)) < 0) {
+			lxc_log_syserror("failed to read socket");
+			return 1;
+		}
+
+		/* Setup the container, ip, names, utsname, ... */
+		if (lxc_setup(name)) {
+			lxc_log_error("failed to setup the container");
+			if (write(sv[0], &sync, sizeof(sync)) < 0)
+				lxc_log_syserror("failed to write the socket");
+			return -1;
+		}
+
+		sys_restart(pid, cfd, flags);
+		lxc_log_syserror("failed to restart");
+
+		/* If the exec fails, tell that to our father */
+		if (write(sv[0], &sync, sizeof(sync)) < 0)
+			lxc_log_syserror("failed to write the socket");
+		
+		exit(1);
+	}
+
+	close(sv[0]);
+	
+	/* Wait for the child to be ready */
+	if (read(sv[1], &sync, sizeof(sync)) < 0) {
+		lxc_log_syserror("failed to read the socket");
+		goto err_pipe_read;
+	}
+
+	/* Create the network configuration */
+	if (clone_flags & CLONE_NEWNET && conf_create_network(name, pid)) {
+		lxc_log_error("failed to create the configured network");
+		goto err_create_network;
+	}
+
+	/* Tell the child to continue its initialization */
+	if (write(sv[1], &sync, sizeof(sync)) < 0) {
+		lxc_log_syserror("failed to write the socket");
+		goto err_pipe_write;
+	}
+
+	/* Wait for the child to exec or returning an error */
+	err = read(sv[1], &sync, sizeof(sync));
+	if (err < 0) {
+		lxc_log_error("failed to read the socket");
+		goto err_pipe_read2;
+	}
+
+	if (err > 0) {
+		lxc_log_error("something went wrong with %d", pid);
+		/* TODO : check status etc ... */
+		waitpid(pid, NULL, 0);
+		goto err_child_failed;
+	}
+
+	asprintf(&val, "%d\n", pid);
+	asprintf(&init, LXCPATH "/%s/init", name);
+	fd = open(init, O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
+	if (fd < 0) {
+		lxc_log_syserror("failed to open '%s'", init);
+		goto err_write;
+	}
+	
+	if (write(fd, val, strlen(val)) < 0) {
+		lxc_log_syserror("failed to write the init pid");
+		goto err_write;
+	}
+
+	close(fd);
+
+	if (lxc_link_nsgroup(name, pid))
+		lxc_log_warning("cgroupfs not found: cgroup disabled");
+
+	if (lxc_setstate(name, RUNNING)) {
+		lxc_log_error("failed to set state to %s", 
+			      lxc_state2str(RUNNING));
+		goto err_state_failed;
+	}
+
+wait_again:
+	if (waitpid(pid, NULL, 0) < 0) {
+		if (errno == EINTR) 
+			goto wait_again;
+		lxc_log_syserror("failed to wait the pid %d", pid);
+		goto err_waitpid_failed;
+	}
+
+	if (lxc_setstate(name, STOPPING))
+		lxc_log_error("failed to set state %s", lxc_state2str(STOPPING));
+
+	if (clone_flags & CLONE_NEWNET && conf_destroy_network(name))
+		lxc_log_error("failed to destroy the network");
+
+	err = 0;
+out:
+	if (lxc_setstate(name, STOPPED))
+		lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
+
+	lxc_unlink_nsgroup(name);
+	unlink(init);
+	free(init);
+	free(val);
+	lxc_put_lock(lock);
+
+	return err;
+
+err_write:
+	close(fd);
+
+err_state_failed:
+err_child_failed:
+err_pipe_read2:
+err_pipe_write:
+	if (clone_flags & CLONE_NEWNET)
+		conf_destroy_network(name);
+err_create_network:
+err_pipe_read:
+err_waitpid_failed:
+	if (lxc_setstate(name, ABORTING))
+		lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
+
+	kill(pid, SIGKILL);
+err_fork_ns:
+	LXC_TTY_DEL_HANDLER(SIGQUIT);
+	LXC_TTY_DEL_HANDLER(SIGINT);
+	close(sv[0]);
+	close(sv[1]);
+err:
+	goto out;
+}