[lxc-devel] [lxc/master] devpts: use max=<count> option on mount

[brauner on Github]

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From d4033a97f9e12cfe8b7012400a12e09577d59a94 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Mon, 31 Jul 2017 22:54:38 +0200
Subject: [PATCH] devpts: use max=<count> option on mount

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 src/lxc/conf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index ab038d36d..25d29c20a 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -1332,7 +1332,8 @@ static int setup_pivot_root(const struct lxc_rootfs *rootfs)
 static int lxc_setup_devpts(int num_pts)
 {
 	int ret;
-	const char *devpts_mntopts = "newinstance,ptmxmode=0666,mode=0620,gid=5";
+	const char *default_devpts_mntopts = "newinstance,ptmxmode=0666,mode=0620,gid=5";
+	char devpts_mntopts[256];
 
 	if (!num_pts) {
 		DEBUG("no new devpts instance will be mounted since no pts "
@@ -1340,6 +1341,11 @@ static int lxc_setup_devpts(int num_pts)
 		return 0;
 	}
 
+	ret = snprintf(devpts_mntopts, sizeof(devpts_mntopts), "%s,max=%d",
+		       default_devpts_mntopts, num_pts);
+	if (ret < 0 || (size_t)ret >= sizeof(devpts_mntopts))
+		return -1;
+
 	/* Unmount old devpts instance. */
 	ret = access("/dev/pts/ptmx", F_OK);
 	if (!ret) {