add: Zygiskd C99 re-write

This commit re-writes Zygiskd to be C99.

zygiskd/root_impl/kernelsu.c

@@ -0,0 +1,54 @@
+#include <stdlib.h>
+
+#include <sys/stat.h>
+#include <sys/prctl.h>
+
+#include "../constants.h"
+
+#include "kernelsu.h"
+
+#define KERNEL_SU_OPTION 0xdeadbeef
+
+#define CMD_GET_VERSION 2
+#define CMD_UID_GRANTED_ROOT 12
+#define CMD_UID_SHOULD_UMOUNT 13
+
+enum RootImplState ksu_get_kernel_su() {
+  int version = 0;
+  prctl(KERNEL_SU_OPTION, CMD_GET_VERSION, &version, 0, 0);
+
+  if (version == 0) return -1;
+
+  if (version >= MIN_KSU_VERSION && version <= MAX_KSU_VERSION) return Supported;
+  
+  if (version >= 1 && version <= MIN_KSU_VERSION - 1) return TooOld;
+
+  return Abnormal;
+}
+
+bool ksu_uid_granted_root(int uid) {
+  uint32_t result = 0;
+  bool granted = false;
+  prctl(KERNEL_SU_OPTION, CMD_UID_GRANTED_ROOT, uid, &granted, &result);
+
+  if (result != KERNEL_SU_OPTION) return false;
+
+  return granted;
+}
+
+bool ksu_uid_should_umount(int uid) {
+  uint32_t result = 0;
+  bool umount = false;
+  prctl(KERNEL_SU_OPTION, CMD_UID_SHOULD_UMOUNT, uid, &umount, &result);
+
+  if (result != KERNEL_SU_OPTION) return false;
+
+  return umount;
+}
+
+bool ksu_uid_is_manager(int uid) {
+  struct stat s;
+  if (stat("/data/user_de/0/me.weishu.kernelsu", &s) == 0) return s.st_uid == (uid_t)uid;
+
+  return false;
+}