Quoting Oren Laadan ([email protected]):
> Based on Serge Hallyn's patch:
>
> "Trivial patch, and I'm not sure whether we want this or want to do
> it this way. But it saves me having to do it during my restart.sh
> wrapper shell-script."
>
> Make sure that the old /dev/pts is un-mounted prior to the mount of
> the new one.
>
> Signed-off-by: Oren Laadan <[email protected]>
> ---
> restart.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/restart.c b/restart.c
> index f42b456..e3c4a5c 100644
> --- a/restart.c
> +++ b/restart.c
> @@ -53,6 +53,7 @@ static char usage_str[] =
> " --signal=SIG send SIG to root task on SIGINT (default: SIGKILL\n"
> " to container root, SIGINT otherwise)\n"
> " --mntns restart under a private mounts namespace\n"
> +" --mount-pty start in a new devpts namespace to supprt ptys\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"
> @@ -275,6 +276,7 @@ int global_send_sigint = -1;
> int global_sent_sigint;
>
> static int ckpt_remount_proc(void);
> +static int ckpt_remount_devpts(void);
>
> static int ckpt_build_tree(struct ckpt_ctx *ctx);
> static int ckpt_init_tree(struct ckpt_ctx *ctx);
> @@ -342,6 +344,7 @@ struct args {
> char *root;
> int wait;
> int mntns;
> + int mnt_pty;
> int show_status;
> int copy_status;
> char *freezer;
> @@ -432,6 +435,7 @@ static void parse_args(struct args *args, int argc, char
> *argv[])
> { "debug", no_argument, NULL, 'd' },
> { "warn-pidzero", no_argument, NULL, 9 },
> { "fail-pidzero", no_argument, NULL, 10 },
> + { "mount-pty", no_argument, NULL, 12 },
> { NULL, 0, NULL, 0 }
> };
> static char optc[] = "hdvkpPwWF:r:i:l:";
> @@ -538,6 +542,9 @@ static void parse_args(struct args *args, int argc, char
> *argv[])
> case 11:
> args->mntns = 1;
> break;
> + case 12:
> + args->mnt_pty = 1;
> + break;
> default:
> usage(usage_str);
> }
> @@ -591,6 +598,9 @@ static void parse_args(struct args *args, int argc, char
> *argv[])
> printf("Invalid used of both -l/--logfile and --logfile-fd\n");
> exit(1);
> }
> +
> + if (args->mnt_pty)
> + args->mntns = 1;
> }
>
> static void report_exit_status(int status, char *str, int debug)
> @@ -785,6 +795,10 @@ int main(int argc, char *argv[])
> exit(1);
> }
>
> + /* remount /dev/pts ? */
> + if (args.mnt_pty && ckpt_remount_devpts() < 0)
> + exit(1);
> +
> /* self-restart ends here: */
> if (args.self) {
> restart(getpid(), STDIN_FILENO, RESTART_TASKSELF, args.logfd);
> @@ -916,6 +930,32 @@ static int ckpt_collect_child(struct ckpt_ctx *ctx)
> return ckpt_parse_status(status, mimic, verbose);
> }
>
> +static int ckpt_remount_devpts(void)
> +{
> + struct stat ptystat;
> +
> + /* make sure /dev/ptmx is a link else we'll just break */
> + if (lstat("/dev/ptmx", &ptystat) < 0) {
> + perror("stat /dev/ptmx");
> + return -1;
> + }
> + if ((ptystat.st_mode & S_IFMT) != S_IFLNK) {
> + ckpt_err("Error: /dev/ptmx must be a link to /dev/pts/ptmx\n");
> + return -1;
> + }
> +
> + if (umount2("/dev/pts", MNT_DETACH) < 0) {
> + perror("umount -l /dev/pts");
> + return -1;
> + }
> + if (mount("pts", "/dev/pts", "devpts", 0, "newinstance") < 0) {
How about making that
if (mount("pts", "/dev/pts", "devpts", 0, "ptmxmode=666,newinstance")
< 0) {
(or take that as another arg if you must)? Otherwise restarting
non-root-owned tasks not only ends up with tasks not able to create
a new terminal, but you can't externally fix that since the mount
is private...
> + perror("mount -t devpts -o newinstance");
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> static int ckpt_close_files(void)
> {
> char fdpath[64], *endp;
> --
> 1.6.3.3
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