Re: [PATCH] restart: rename and cleanup switch to indicate signal-on-interrupt

["Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

Quoting Oren Laadan (orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org):
> When restartinig in --wait mode, an interrupt to the coordinator
> translates to a signal to the root task. This patch fixes and
> imrpoves the interface and logic of sending such signals.
> 
> Signed-off-by: Oren Laadan <orenl-eQaUEPhvms7ENvBUuze7eA@public.gmane.org>

Acked-by: Serge Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>

> ---
>  restart.c |  132 ++++++++++++++++++++++++++++++++++++++++++++++++++-----------
>  1 files changed, 109 insertions(+), 23 deletions(-)
> 
> diff --git a/restart.c b/restart.c
> index fbcc299..a25aaa9 100644
> --- a/restart.c
> +++ b/restart.c
> @@ -58,21 +58,22 @@ static char usage_str[] =
>  "usage: restart [opts]\n"
>  "  restart restores from a checkpoint image by first creating in userspace\n"
>  "  the original tasks tree, and then calling sys_restart by each task.\n"
> -"\tOptions:\n"
> -"\t -h,--help             print this help message\n"
> -"\t -p,--pidns            create a new pid namspace (default with --pids)\n"
> -"\t -P,--no-pidns         do not create a new pid namspace (default)\n"
> -"\t    --pidns-intr=SIG   send SIG to root task on SIGINT (default: SIGKILL)\n"
> -"\t    --pids             restore original pids (default with --pidns)\n"
> -"\t -i,--inspect          inspect image on-the-fly for error records\n"
> -"\t -r,--root=ROOT        restart under the directory ROOT instead of current\n"
> -"\t -w,--wait             wait for (root) task to termiate (default)\n"
> -"\t    --show-status      show exit status of (root) task (implies -w)\n"
> -"\t    --copy-status      imitate exit status of (root) task (implies -w)\n"
> -"\t -W,--no-wait          do not wait for (root) task to terminate\n"
> -"\t -F,--freezer=CGROUP   freeze tasks in freezer group CGROUP on success\n"
> -"\t -v,--verbose          verbose output\n"
> -"\t -d,--debug            debugging output\n"
> +"Options:\n"
> +"  -h,--help             print this help message\n"
> +"  -p,--pidns            create a new pid namspace (default with --pids)\n"
> +"  -P,--no-pidns         do not create a new pid namespace (default)\n"
> +"     --pids             restore original pids (default with --pidns)\n"
> +"  -i,--inspect          inspect image on-the-fly for error records\n"
> +"  -r,--root=ROOT        restart under the directory ROOT instead of current\n"
> +"     --signal=SIG       send SIG to root task on SIGINT (default: SIGKILL\n"
> +"                        to container root, SIGINT otherwise)\n"
> +"  -w,--wait             wait for root task to termiate (default)\n"
> +"     --show-status      show exit status of root task (implies -w)\n"
> +"     --copy-status      imitate exit status of root task (implies -w)\n"
> +"  -W,--no-wait          do not wait for root task to terminate\n"
> +"  -F,--freezer=CGROUP   freeze tasks in freezer group CGROUP on success\n"
> +"  -v,--verbose          verbose output\n"
> +"  -d,--debug            debugging output\n"
>  "";
> 
>  /*
> @@ -128,6 +129,69 @@ static char usage_str[] =
>  			printf(__VA_ARGS__);	\
>  	} while(0)
> 
> +#define SIGNAL_ENTRY(signal)  { SIG ## signal, #signal }
> +
> +struct {
> +	int signum;
> +	char *sigstr;
> +} signal_array[] = {
> +	{ 0, "NONE" },
> +	SIGNAL_ENTRY(ALRM),
> +	SIGNAL_ENTRY(HUP),
> +	SIGNAL_ENTRY(INT),
> +	SIGNAL_ENTRY(KILL),
> +	SIGNAL_ENTRY(PIPE),
> +	SIGNAL_ENTRY(POLL),
> +	SIGNAL_ENTRY(PROF),
> +	SIGNAL_ENTRY(TERM),
> +	SIGNAL_ENTRY(USR1),
> +	SIGNAL_ENTRY(USR2),
> +	SIGNAL_ENTRY(VTALRM),
> +	SIGNAL_ENTRY(STKFLT),
> +	SIGNAL_ENTRY(PWR),
> +	SIGNAL_ENTRY(WINCH),
> +	SIGNAL_ENTRY(CHLD),
> +	SIGNAL_ENTRY(URG),
> +	SIGNAL_ENTRY(TTIN),
> +	SIGNAL_ENTRY(TTOU),
> +	SIGNAL_ENTRY(STOP),
> +	SIGNAL_ENTRY(CONT),
> +	SIGNAL_ENTRY(ABRT),
> +	SIGNAL_ENTRY(FPE),
> +	SIGNAL_ENTRY(ILL),
> +	SIGNAL_ENTRY(QUIT),
> +	SIGNAL_ENTRY(SEGV),
> +	SIGNAL_ENTRY(TRAP),
> +	SIGNAL_ENTRY(SYS),
> +	SIGNAL_ENTRY(BUS),
> +	SIGNAL_ENTRY(XCPU),
> +	SIGNAL_ENTRY(XFSZ),
> +	{ -1, "LAST" },
> +};
> +
> +static char *sig2str(int sig)
> +{
> +	int i = 0;
> +
> +	do {
> +		if (signal_array[i].signum == sig)
> +			return signal_array[i].sigstr;
> +	} while (signal_array[++i].signum >= 0);
> +	return "UNKNOWN SIGNAL";
> +}
> +
> +static int str2sig(char *str)
> +{
> +	int sig = 0;
> +
> +	do {
> +		if (!strcmp(signal_array[sig].sigstr, str))
> +			return signal_array[sig].signum;
> +	} while (signal_array[++sig].signum >= 0);
> +
> +	return -1;
> +}
> +
>  inline static int restart(pid_t pid, int fd, unsigned long flags)
>  {
>  	return syscall(__NR_restart, pid, fd, flags);
> @@ -287,14 +351,26 @@ static void usage(char *str)
>  	exit(1);
>  }
> 
> +/* negative retval means error */
> +static int str2num(char *str)
> +{
> +	char *nptr;
> +	int num;
> +
> +	num = strtol(str, &nptr, 10);
> +	if (nptr - str != strlen(str))
> +		num = -1;
> +	return num;
> +}
> +
>  static void parse_args(struct args *args, int argc, char *argv[])
>  {
>  	static struct option opts[] = {
>  		{ "help",	no_argument,		NULL, 'h' },
>  		{ "pidns",	no_argument,		NULL, 'p' },
> -		{ "pidns-signal",	required_argument,	NULL, '4' },
>  		{ "no-pidns",	no_argument,		NULL, 'P' },
>  		{ "pids",	no_argument,		NULL, 3 },
> +		{ "signal",	required_argument,	NULL, 4 },
>  		{ "inspect",	no_argument,		NULL, 'i' },
>  		{ "root",	required_argument,		NULL, 'r' },
>  		{ "wait",	no_argument,		NULL, 'w' },
> @@ -336,9 +412,11 @@ static void parse_args(struct args *args, int argc, char *argv[])
>  			args->no_pidns = 1;
>  			break;
>  		case 4:
> -			sig = atoi(optarg);
> +			sig = str2sig(optarg);
> +			if (sig < 0)
> +				sig = str2num(optarg);
>  			if (sig < 0 || sig >= NSIG) {
> -				printf("restart: invalid signal number\n");
> +				printf("restart: invalid signal\n");
>  				exit(1);
>  			}
>  			global_send_sigint = sig;
> @@ -461,13 +539,21 @@ static void sigint_handler(int sig)
>  {
>  	pid_t pid = global_child_pid;
> 
> -	ckpt_verbose("SIGINT sent to restarted tasks\n");
> +	sig = global_send_sigint;
> +	if (!sig) {
> +		ckpt_verbose("Interrupt attempt .. ignored.\n");
> +		return;
> +	}
> +
> +	ckpt_verbose("Interrupted: sent SIG%s to "
> +		     "restarted tasks\n", sig2str(sig));
> 
>  	if (pid) {
> -		ckpt_dbg("delegating SIGINT to child %d "
> -			 "(coordinator or root task)\n", pid);
> -		kill(-pid, SIGINT);
> -		kill(pid, SIGINT);
> +		ckpt_dbg("delegating SIG%s to child %d "
> +			 "(coordinator/root task)\n",
> +			 sig2str(sig), pid);
> +		kill(-pid, sig);
> +		kill(pid, sig);
>  	}
>  }
> 
> -- 
> 1.6.0.4
> 
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