text: /**
   *    Copyright 2017 jmpews
   *
   *    Licensed under the Apache License, Version 2.0 (the "License");
   *    you may not use this file except in compliance with the License.
   *    You may obtain a copy of the License at
   *
   *        http://www.apache.org/licenses/LICENSE-2.0
   *
   *    Unless required by applicable law or agreed to in writing, software
   *    distributed under the License is distributed on an "AS IS" BASIS,
   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *    See the License for the specific language governing permissions and
   *    limitations under the License.
   */
  
  #include "hookzz.h"
  #include <stdio.h>
  #include <unistd.h>
  
  static void hack_this_function() {
  #ifdef __arm64__
      __asm__("mov X0, #0\n"
              "mov w16, #20\n"
              "svc #0x80\n"
              "nop\n"
              "nop\n"
              "nop\n"
              "nop");
  #endif
  }
  
  static void sorry_to_exit() {
  #ifdef __arm64__
      __asm__("mov X0, #0\n"
              "mov w16, #1\n"
              "svc #0x80");
  #endif
  }
  
  void getpid_pre_call(RegState *rs, ThreadStack *threadstack, CallStack *callstack) {
      unsigned long request = *(unsigned long *)(&rs->general.regs.x16);
      printf("request(x16) is: %ld\n", request);
      printf("x0 is: %ld\n", (long)rs->general.regs.x0);
  }
  
  void getpid_half_call(RegState *rs, ThreadStack *threadstack, CallStack *callstack) {
      pid_t x0 = (pid_t)(rs->general.regs.x0);
      printf("getpid() return at x0 is: %d\n", x0);
  }
  
  __attribute__((constructor)) void test_hook_address() {
      void *hack_this_function_ptr = (void *)hack_this_function;
      // hook address with only `pre_call`
      // ZzBuildHookAddress(hack_this_function_ptr + 8, hack_this_function_ptr + 12, (void
      // *)getpid_pre_call, NULL);
  
      // hook address with only `half_call`
      // ZzBuildHookAddress(hack_this_function_ptr + 8, hack_this_function_ptr + 12, NULL, (void
      // *)getpid_half_call);
  
      // hook address with both `half_call` and `pre_call`
      ZzBuildHookAddress(hack_this_function_ptr + 8, hack_this_function_ptr + 12, getpid_pre_call, getpid_half_call,
                         TRUE);
      ZzEnableHook((void *)hack_this_function_ptr + 8);
  
      void *sorry_to_exit_ptr = (void *)sorry_to_exit;
      unsigned long nop_bytes = 0xD503201F;
      ZzRuntimeCodePatch((unsigned long)sorry_to_exit_ptr + 8, (zpointer)&nop_bytes, 4);
  
      hack_this_function();
      sorry_to_exit();
  
      printf("hack success -.0\n");
  }
  
  /*
  (lldb) disass -n hack_this_function
  test_hook_address.dylib`hack_this_function:
      0x1000b0280 <+0>:  mov    x0, #0x0
      0x1000b0284 <+4>:  mov    w16, #0x14
      0x1000b0288 <+8>:  svc    #0x80
      0x1000b028c <+12>: ret
  
  (lldb) disass -n sorry_to_exit
  test_hook_address.dylib`sorry_to_exit:
      0x1000b0290 <+0>:  mov    x0, #0x0
      0x1000b0294 <+4>:  mov    w16, #0x1
      0x1000b0298 <+8>:  svc    #0x80
      0x1000b029c <+12>: ret
  
  (lldb) c
  Process 41414 resuming
  request(x16) is: 20
  x0 is: 0
  getpid() return at x0 is: 41414
  hack success -.0
  (lldb) disass -n hack_this_function
  test_hook_address.dylib`hack_this_function:
      0x1000b0280 <+0>:  mov    x0, #0x0
      0x1000b0284 <+4>:  mov    w16, #0x14
      0x1000b0288 <+8>:  b      0x1001202cc
      0x1000b028c <+12>: ret
  
  (lldb) disass -n sorry_to_exit
  test_hook_address.dylib`sorry_to_exit:
      0x1000b0290 <+0>:  mov    x0, #0x0
      0x1000b0294 <+4>:  mov    w16, #0x1
      0x1000b0298 <+8>:  nop
      0x1000b029c <+12>: ret
  */