From 75d219f0cc6be29d192677c5a8bd1bfd9528437b Mon Sep 17 00:00:00 2001 From: Tycho Andersen Date: Fri, 26 Aug 2016 16:07:19 +0000 Subject: [PATCH] c/r: use /proc/self/tid/children instead of pidfile All we really needed a unique temp file for was passing the pid. Since CRIU opened this with O_EXCL | O_CREAT, this was "safe" (users could still overwrite it afterwards, but the monitor would immediately die since the only valid number in there was the init process). In any case, we can just read /proc/self/tid/children, which lists the child process. Closes #1150 Signed-off-by: Tycho Andersen --- src/lxc/criu.c | 38 ++++++++++++++------------------------ 1 file changed, 14 insertions(+), 24 deletions(-) diff --git a/src/lxc/criu.c b/src/lxc/criu.c index 65998ed2b5..76d7080723 100644 --- a/src/lxc/criu.c +++ b/src/lxc/criu.c @@ -69,7 +69,6 @@ struct criu_opts { char tty_id[32]; /* the criu tty id for /dev/console, i.e. "tty[${rdev}:${dev}]" */ /* restore: the file to write the init process' pid into */ - char *pidfile; const char *cgroup_path; int console_fd; /* The path that is bind mounted from /dev/console, if any. We don't @@ -176,10 +175,10 @@ static void exec_criu(struct criu_opts *opts) static_args += 2; } else if (strcmp(opts->action, "restore") == 0) { /* --root $(lxc_mount_point) --restore-detached - * --restore-sibling --pidfile $foo --cgroup-root $foo + * --restore-sibling --cgroup-root $foo * --lsm-profile apparmor:whatever */ - static_args += 10; + static_args += 8; tty_info[0] = 0; if (load_tty_major_minor(opts->user->directory, tty_info, sizeof(tty_info))) @@ -330,8 +329,6 @@ static void exec_criu(struct criu_opts *opts) DECLARE_ARG(opts->c->lxc_conf->rootfs.mount); DECLARE_ARG("--restore-detached"); DECLARE_ARG("--restore-sibling"); - DECLARE_ARG("--pidfile"); - DECLARE_ARG(opts->pidfile); DECLARE_ARG("--cgroup-root"); DECLARE_ARG(opts->cgroup_path); @@ -604,13 +601,8 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_ { pid_t pid; struct lxc_handler *handler; - int fd, status; + int status; int pipes[2] = {-1, -1}; - char pidfile[] = "criu_restore_XXXXXX"; - - fd = mkstemp(pidfile); - if (fd < 0) - goto out; handler = lxc_init(c->name, c->lxc_conf, c->config_path); if (!handler) @@ -690,7 +682,6 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_ os.action = "restore"; os.user = opts; os.c = c; - os.pidfile = pidfile; os.cgroup_path = cgroup_canonical_path(handler); os.console_fd = c->lxc_conf->console.slave; os.criu_version = criu_version; @@ -742,8 +733,9 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_ } if (WIFEXITED(status)) { + char buf[4096]; + if (WEXITSTATUS(status)) { - char buf[4096]; int n; n = read(pipes[0], buf, sizeof(buf)); @@ -758,18 +750,21 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_ goto out_fini_handler; } else { int ret; - FILE *f = fdopen(fd, "r"); + + ret = snprintf(buf, sizeof(buf), "/proc/self/task/%" PRId64 "/children", syscall(__NR_gettid)); + if (ret < 0 || ret >= sizeof(buf)) { + ERROR("snprintf'd too many characters: %d", ret); + goto out_fini_handler; + } + + FILE *f = fopen(buf, "r"); if (!f) { - SYSERROR("couldn't read restore's init pidfile %s\n", pidfile); + SYSERROR("couldn't read restore's children file %s\n", buf); goto out_fini_handler; } - fd = -1; ret = fscanf(f, "%d", (int*) &handler->pid); fclose(f); - if (unlink(pidfile) < 0 && errno != ENOENT) - SYSERROR("unlinking pidfile failed"); - if (ret != 1) { ERROR("reading restore pid failed"); goto out_fini_handler; @@ -809,8 +804,6 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_ close(pipes[1]); lxc_fini(c->name, handler); - if (unlink(pidfile) < 0 && errno != ENOENT) - SYSERROR("unlinking pidfile failed"); out: if (status_pipe >= 0) { @@ -821,9 +814,6 @@ static void do_restore(struct lxc_container *c, int status_pipe, struct migrate_ close(status_pipe); } - if (fd > 0) - close(fd); - exit(1); }