[PATCH user-cr] Allow for logfile for kernel debug messages

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

This is the user-cr patch corresponding to the logfile kernel
patch.

Logfile is specified using -l LOGFILE or --logfile=LOGFILE, i.e.

	checkpoint $pid -o ckpt.out -l ckpt.debug
	restart -l rstr.debug -i ckpt.out

If the logfile is unspecified, -1 will be sent for logfd to the kernel,
and there will be no debug log.   If specified, then checkpoint and
restart debug msgs will be sent to the logfile.

Signed-off-by: Serge E. Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 checkpoint.c |   22 ++++++++++++++++++----
 restart.c    |   29 +++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/checkpoint.c b/checkpoint.c
index c116daf..989e5c4 100644
--- a/checkpoint.c
+++ b/checkpoint.c
@@ -32,6 +32,7 @@ static char usage_str[] =
 "\tOptions:\n"
 "  -h,--help             print this help message\n"
 "  -o,--output=FILE      write data to FILE instead of standard output\n"
+"  -l,--logfile=FILE     write kernel debug data to FILE (default=nowhere)\n"
 "  -c,--container        require the PID is a container-init\n"
 "  -v,--verbose          verbose output\n"
 "";
@@ -40,11 +41,12 @@ struct args {
 	char *output;
 	int container;
 	int verbose;
+	char *logfile;
 };
 
-inline static int checkpoint(pid_t pid, int fd, unsigned long flags)
+inline static int checkpoint(pid_t pid, int fd, unsigned long flags, int logfd)
 {
-	return syscall(__NR_checkpoint, pid, fd, flags);
+	return syscall(__NR_checkpoint, pid, fd, flags, logfd);
 }
 
 static void usage(char *str)
@@ -59,10 +61,11 @@ static void parse_args(struct args *args, int argc, char *argv[])
 		{ "help",	no_argument,		NULL, 'h' },
 		{ "output",	required_argument,	NULL, 'o' },
 		{ "container",	no_argument,		NULL, 'c' },
+		{ "logfile",	required_argument,	NULL, 'l' },
 		{ "verbose",	no_argument,		NULL, 'v' },
 		{ NULL,		0,			NULL, 0 }
 	};
-	static char optc[] = "hvco:";
+	static char optc[] = "hvco:l:";
 
 	while (1) {
 		int c = getopt_long(argc, argv, optc, opts, NULL);
@@ -79,6 +82,9 @@ static void parse_args(struct args *args, int argc, char *argv[])
 		case 'c':
 			args->container = 1;
 			break;
+		case 'l':
+			args->logfile = optarg;
+			break;
 		case 'v':
 			args->verbose = 1;
 			break;
@@ -94,6 +100,7 @@ int main(int argc, char *argv[])
 	unsigned long flags = 0;
 	pid_t pid;
 	int ret;
+	int logfd;
 
 	memset(&args, 0, sizeof(args));
 	parse_args(&args, argc, argv);
@@ -125,8 +132,15 @@ int main(int argc, char *argv[])
 		if (ret != STDOUT_FILENO)
 			close(ret);
 	}
+	if (args.logfile) {
+		logfd = open(args.logfile, O_RDWR | O_CREAT, 0600);
+		if (logfd < 0) {
+			perror("open logfile");
+			exit(1);
+		}
+	}
 
-	ret = checkpoint(pid, STDOUT_FILENO, flags);
+	ret = checkpoint(pid, STDOUT_FILENO, flags, logfd);
 
 	if (ret < 0) {
 		perror("checkpoint");
diff --git a/restart.c b/restart.c
index fbaab88..561b941 100644
--- a/restart.c
+++ b/restart.c
@@ -75,6 +75,7 @@ static char usage_str[] =
 "  -i,--input=FILE      read data from FILE instead of standard input\n"
 "     --inspect          inspect image on-the-fly for error records\n"
 "  -v,--verbose          verbose output\n"
+"  -l,--log=FILE         logfile for kernel debug info\n"
 "  -d,--debug            debugging output\n"
 "";
 
@@ -194,9 +195,9 @@ static int str2sig(char *str)
 	return -1;
 }
 
-inline static int restart(pid_t pid, int fd, unsigned long flags)
+inline static int restart(pid_t pid, int fd, unsigned long flags, int logfd)
 {
-	return syscall(__NR_restart, pid, fd, flags);
+	return syscall(__NR_restart, pid, fd, flags, logfd);
 }
 
 #define BUFSIZE  (4 * 4096)
@@ -252,6 +253,8 @@ struct ckpt_ctx {
 	int pipe_out;
 	int pids_nr;
 
+	int logfd;
+
 	int pipe_child[2];	/* for children to report status */
 	int pipe_feed[2];	/* for feeder to provide input */
 
@@ -352,6 +355,7 @@ struct args {
 	int copy_status;
 	char *freezer;
 	char *input;
+	char *logfile;
 };
 
 static void usage(char *str)
@@ -390,10 +394,11 @@ static void parse_args(struct args *args, int argc, char *argv[])
 		{ "no-wait",	no_argument,		NULL, 'W' },
 		{ "freezer",	required_argument,	NULL, 'F' },
 		{ "verbose",	no_argument,		NULL, 'v' },
+		{ "log",	required_argument,	NULL, 'l' },
 		{ "debug",	no_argument,		NULL, 'd' },
 		{ NULL,		0,			NULL, 0 }
 	};
-	static char optc[] = "hdvpPwWF:r:i:";
+	static char optc[] = "hdvpPwWF:r:i:l:";
 
 	int sig;
 
@@ -416,6 +421,9 @@ static void parse_args(struct args *args, int argc, char *argv[])
 		case 5:  /* --inspect */
 			args->inspect = 1;
 			break;
+		case 'l':
+			args->logfile = optarg;
+			break;
 		case 'i':
 			args->input = optarg;
 			break;
@@ -666,6 +674,15 @@ int main(int argc, char *argv[])
 			close(ret);
 	}
 
+	ctx.logfd = -1;
+	if (args.logfile) {
+		ctx.logfd = open(args.logfile, O_RDWR | O_CREAT, 0600);
+		if (ctx.logfd < 0) {
+			perror("open log file");
+			exit(1);
+		}
+	}
+
 	/* freezer preparation */
 	if (args.freezer && freezer_prepare(&ctx) < 0)
 		exit(1);
@@ -678,7 +695,7 @@ int main(int argc, char *argv[])
 
 	/* self-restart ends here: */
 	if (args.self) {
-		restart(getpid(), STDIN_FILENO, RESTART_TASKSELF);
+		restart(getpid(), STDIN_FILENO, RESTART_TASKSELF, ctx.logfd);
 		/* reach here if restart(2) failed ! */
 		perror("restart");
 		exit(1);
@@ -929,7 +946,7 @@ static int ckpt_coordinator(struct ckpt_ctx *ctx)
 	if (ctx->args->freezer)
 		flags |= RESTART_FROZEN;
 
-	ret = restart(root_pid, STDIN_FILENO, flags);
+	ret = restart(root_pid, STDIN_FILENO, flags, ctx->logfd);
 
 	if (ret < 0) {
 		perror("restart failed");
@@ -1590,7 +1607,7 @@ static int ckpt_make_tree(struct ckpt_ctx *ctx, struct task *task)
 
 	/* on success this doesn't return */
 	ckpt_dbg("about to call sys_restart(), flags %#lx\n", flags);
-	ret = restart(0, STDIN_FILENO, flags);
+	ret = restart(0, STDIN_FILENO, flags, ctx->logfd);
 	if (ret < 0)
 		perror("task restore failed");
 	return ret;
-- 
1.6.1.1