From cf565d0145f728d16d3f9156a86a2c286e0ccc66 Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Mon, 3 Jul 2017 01:02:11 +0800
Subject: [PATCH] Add mount ns kernel support detection

---
 jni/magiskhide/proc_monitor.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/jni/magiskhide/proc_monitor.c b/jni/magiskhide/proc_monitor.c
index 176fc37bd..f8fbeafd0 100644
--- a/jni/magiskhide/proc_monitor.c
+++ b/jni/magiskhide/proc_monitor.c
@@ -22,12 +22,6 @@ static char init_ns[32], zygote_ns[2][32];
 static int log_pid, log_fd;
 static char *buffer;
 
-static void read_namespace(const int pid, char* target, const size_t size) {
-	char path[32];
-	snprintf(path, sizeof(path), "/proc/%d/ns/mnt", pid);
-	xreadlink(path, target, size);
-}
-
 // Workaround for the lack of pthread_cancel
 static void quit_pthread(int sig) {
 	err_handler = do_nothing;
@@ -53,6 +47,22 @@ static void quit_pthread(int sig) {
 	pthread_exit(NULL);
 }
 
+static void proc_monitor_err() {
+	LOGD("proc_monitor: error occured, stopping magiskhide services\n");
+	quit_pthread(SIGUSR1);
+}
+
+static void read_namespace(const int pid, char* target, const size_t size) {
+	char path[32];
+	snprintf(path, sizeof(path), "/proc/%d/ns/mnt", pid);
+	if (access(path, R_OK) == -1) {
+		LOGE("proc_monitor: Your kernel doesn't support mount namespace :(\n");
+		proc_monitor_err();
+		return;
+	}
+	xreadlink(path, target, size);
+}
+
 static void store_zygote_ns(int pid) {
 	if (zygote_num == 2) return;
 	do {
@@ -62,11 +72,6 @@ static void store_zygote_ns(int pid) {
 	++zygote_num;
 }
 
-static void proc_monitor_err() {
-	LOGD("proc_monitor: error occured, stopping magiskhide services\n");
-	quit_pthread(SIGUSR1);
-}
-
 void proc_monitor() {
 	// Register the cancel signal
 	struct sigaction act;