Get random separately

native/src/base/misc.cpp

@@ -33,7 +33,7 @@ int fork_no_orphan() {
     return 0;
 }
 
-int gen_rand_str(char *buf, int len, const void *seed_buf, bool varlen) {
+mt19937_64 &get_rand(const void *seed_buf) {
     static mt19937_64 gen([&] {
         mt19937_64::result_type seed;
         if (seed_buf == nullptr) {
@@ -45,6 +45,11 @@ int gen_rand_str(char *buf, int len, const void *seed_buf, bool varlen) {
         }
         return seed;
     }());
+    return gen;
+}
+
+int gen_rand_str(char *buf, int len, bool varlen) {
+    auto gen = get_rand();
 
     if (len == 0)
         return 0;

native/src/base/misc.hpp

@@ -5,6 +5,7 @@
 #include <functional>
 #include <string_view>
 #include <bitset>
+#include <random>
 
 #include <base-rs.hpp>
 
@@ -159,7 +160,8 @@ void init_argv0(int argc, char **argv);
 void set_nice_name(const char *name);
 uint32_t binary_gcd(uint32_t u, uint32_t v);
 int switch_mnt_ns(int pid);
-int gen_rand_str(char *buf, int len, const void *seed_buf = nullptr, bool varlen = true);
+std::mt19937_64 &get_rand(const void *seed_buf = nullptr);
+int gen_rand_str(char *buf, int len, bool varlen = true);
 std::string &replace_all(std::string &str, std::string_view from, std::string_view to);
 std::vector<std::string> split(const std::string &s, const std::string &delims);
 std::vector<std::string_view> split_ro(std::string_view, std::string_view delims);

native/src/init/rootdir.cpp

@@ -209,7 +209,7 @@ void MagiskInit::parse_config_file() {
         }
         return true;
     });
-    gen_rand_str(nullptr, 0, &seed);
+    get_rand(&seed);
 }
 
 #define ROOTMIR     MIRRDIR "/system_root"