sfd_type: Add SELF_STDIN_OFF service fd and call helpers where needed

We will need it for slave ttys migration. They serve for one purpose --
to clone self stdio descriptor and use it with tty layer, which will
be addressed in further patches.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -88,6 +88,9 @@ static int crtools_prepare_shared(void)
 	if (collect_inet_sockets())
 		return -1;
 
+	if (tty_prep_fds())
+		return -1;
+
 	return 0;
 }
 

files.c

@@ -535,7 +535,7 @@ int prepare_fds(struct pstree_item *me)
 
 	ret = close_old_fds(me);
 	if (ret)
-		return ret;
+		goto err;
 
 	pr_info("Opening fdinfo-s\n");
 
@@ -562,6 +562,8 @@ int prepare_fds(struct pstree_item *me)
 			break;
 	}
 
+err:
+	tty_fini_fds();
 	return ret;
 }
 

include/crtools.h

@@ -116,6 +116,7 @@ enum sfd_type {
 	SELF_EXE_FD_OFF,
 	PROC_FD_OFF,
 	CTL_TTY_OFF,
+	SELF_STDIN_OFF,
 
 	SERVICE_FD_MAX
 };

include/tty.h

@@ -20,4 +20,7 @@ extern int tty_setup_slavery(void);
 
 extern int tty_verify_active_pairs(void);
 
+extern int tty_prep_fds(void);
+extern void tty_fini_fds(void);
+
 #endif /* CR_TTY_H__ */

tty.c

@@ -84,6 +84,7 @@ struct tty_info {
 
 static LIST_HEAD(all_tty_info_entries);
 static LIST_HEAD(all_ttys);
+static int self_stdin = -1;
 
 /*
  * Usually an application has not that many ttys opened.
@@ -1022,3 +1023,26 @@ int dump_tty(struct fd_parms *p, int lfd, const struct cr_fdset *set)
 {
 	return do_dump_gen_file(p, lfd, &tty_ops, set);
 }
+
+int tty_prep_fds(void)
+{
+	self_stdin = get_service_fd(SELF_STDIN_OFF);
+
+	if (!isatty(STDIN_FILENO)) {
+		pr_err("Standart stream is not a terminal, aborting\n");
+		return -1;
+	}
+
+	if (dup2(STDIN_FILENO, self_stdin) < 0) {
+		self_stdin = -1;
+		pr_perror("Can't dup stdin to SELF_STDIN_OFF");
+		return -1;
+	}
+
+	return 0;
+}
+
+void tty_fini_fds(void)
+{
+	close_safe(&self_stdin);
+}