[Devel] Re: [PATCH 4/5][lxc] Hook up lxc_restart() with app_restart()

[Daniel Lezcano]

Sukadev Bhattiprolu wrote:
> From: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
> Date: Thu, 11 Mar 2010 20:47:56 -0800
> Subject: [PATCH 4/5][lxc] Hook up lxc_restart() with app_restart()
> 
> Have lxc_restart() call app_restart() implemented in the 'restart.o' from
> USER-CR git tree.
> 
> Changelog[v2]:
> 	- Link with restart.o from usercr rather than libcheckpoint.a
> 	- rename 'struct restart_args' to 'struct app_restart_args'
> 	- Initialize the new field app_restart_args->uerrfd
> 	- (Oren Laadan)Remove ->send_sigint field from 'struct app_restart_args'
> ---
>  src/lxc/restart.c |  104 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 104 insertions(+), 0 deletions(-)
> 
> diff --git a/src/lxc/restart.c b/src/lxc/restart.c
> index 467489e..945435c 100644
> --- a/src/lxc/restart.c
> +++ b/src/lxc/restart.c
> @@ -22,11 +22,115 @@
>   */
>  #include <lxc/lxc.h>
>  #include <lxc/log.h>
> +#include <lxc/start.h>
> +#include <lxc/namespace.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <signal.h>
> +#include <sys/prctl.h>
> +#include <app-checkpoint.h>
> +
> +struct lxc_restart_arg {
> +	const char *name;
> +	const char *statefile;
> +	char *const argv;
> +	struct lxc_handler *handler;
> +};
> 
>  lxc_log_define(lxc_restart, lxc);
> 
> +static int do_restart(struct lxc_restart_arg *lxcarg)
> +{
> +	int pid;
> +	struct lxc_handler *handler = lxcarg->handler;
> +	const char *name = lxcarg->name;
> +	char *const argv = lxcarg->argv;
> +	const char *statefile = lxcarg->statefile;
> +	struct app_restart_args restart_args;
> +
> +        if (sigprocmask(SIG_SETMASK, &handler->oldmask, NULL)) {
> +                SYSERROR("failed to set sigprocmask");
> +                return -1;
> +        }
> +
> +        if (prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0)) {
> +                SYSERROR("failed to set pdeath signal");
> +                return -1;
> +        }
> +
> +	memset(&restart_args, 0, sizeof(restart_args));
> +
> +	if (statefile) {

Why do you need to check if statefile is valid ? It's a mandatory 
option, no ? if it is not specified, we should not reach this point.

> +		restart_args.infd = open(statefile, O_RDONLY, 0);
> +		if (restart_args.infd < 0) {
> +			SYSERROR("Failed to open statefile %s\n", statefile);
> +			return -1;
> +		}
> +	}
> +
> +	restart_args.pids = 1;
> +	restart_args.pidns = 1;
> +	restart_args.mnt_pty = 1;
> +	restart_args.mntns = 1;
> +	restart_args.klogfd = -1;
> +	restart_args.ulogfd = lxc_log_fd;
> +	restart_args.uerrfd = fileno(stderr);
> +	restart_args.debug = 1;
> +	restart_args.wait = 0;
> +
> +        pid = app_restart(&restart_args);
> +
> +        return pid;
> +}
> +
>  int lxc_restart(const char *name, const char *statefile, struct lxc_conf *conf,
>  		int flags)
>  {
> +	int err;
> +	int status;
> +	struct lxc_handler *handler;
> +	struct lxc_restart_arg lxcarg = {
> +		.name = name,
> +		.statefile = statefile,
> +		.handler = NULL,
> +	};
> +
> +	handler = lxc_init(name, conf);
> +	if (!handler) {
> +		ERROR("failed to initialize the container");
> +		return -1;
> +	}
> +
> +	lxcarg.handler = handler;
> +	handler->pid = do_restart(&lxcarg);
> +
> +	INFO("do_restart(): returns pid %d\n", handler->pid);
> +	lxc_rename_nsgroup(name, handler);
> +
> +	err = lxc_close_all_inherited_fd();
> +	if (err) {
> +		ERROR("unable to close inherited fds");
> +		goto out_abort;
> +	}

A small change here, recently committed. Now we check there is *no* 
inherited fd at this point instead of trying to detect them.

> +	err = lxc_poll(name, handler);
> +	if (err) {
> +		ERROR("mainloop exited with an error");
> +		goto out_abort;
> +	}
> +
> +	while (waitpid(handler->pid, &status, 0) < 0 && errno == EINTR)
> +		continue;
> +
> +	err =  lxc_error_set_and_log(handler->pid, status);
> +
> +out_fini:
> +	lxc_fini(name, handler);
> +	return err;
> +
> +out_abort:
> +	lxc_abort(name, handler);
> +	goto out_fini;
> +
>  	return 0;
>  }
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