proc_fuse: add disable_uptime feature

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>

Author: mihalicyn

src/bindings.c

@@ -41,6 +41,7 @@
 #include "utils.h"
 
 feature_t per_instance_features[63] = {
+	{ .name = "disable_uptime", },
 	{ }
 };
 

src/bindings.h

@@ -165,6 +165,7 @@ struct pidns_store {
 	/* Do not free on liblxcfs reload (contains useful persistent data) */
 	bool keep_on_reload;
 
+#define	LXCFS_FEATURES_DISABLE_UPTIME	(1 << 0)
 	/* bit mask for per-instance configuration options (on/off) */
 	__u64 features;
 };

src/proc_fuse.c

@@ -942,6 +942,9 @@ static int proc_uptime_read(char *buf, size_t size, off_t offset,
 		return total_len;
 	}
 
+	if (check_set_lxcfs_feature(fc->pid, LXCFS_FEATURE_CHECK, LXCFS_FEATURES_DISABLE_UPTIME))
+		return read_file_fuse("/proc/uptime", buf, size, d);
+
 	reaperage = get_reaper_age(fc->pid);
 	/*
 	 * To understand why this is done, please read the comment to the