text: //
  //  KSSymbolicator.c
  //
  //  Copyright (c) 2016 Karl Stenerud. All rights reserved.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall remain in place
  // in this source code.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  //
  
  
  #include "KSSymbolicator.h"
  #include "KSDynamicLinker.h"
  
  
  /** Remove any pointer tagging from an instruction address
   * On armv7 the least significant bit of the pointer distinguishes
   * between thumb mode (2-byte instructions) and normal mode (4-byte instructions).
   * On arm64 all instructions are 4-bytes wide so the two least significant
   * bytes should always be 0.
   * On x86_64 and i386, instructions are variable length so all bits are
   * signficant.
   */
  #if defined(__arm__)
  #define DETAG_INSTRUCTION_ADDRESS(A) ((A) & ~(1UL))
  #elif defined(__arm64__)
  #define DETAG_INSTRUCTION_ADDRESS(A) ((A) & ~(3UL))
  #else
  #define DETAG_INSTRUCTION_ADDRESS(A) (A)
  #endif
  
  /** Step backwards by one instruction.
   * The backtrace of an objective-C program is expected to contain return
   * addresses not call instructions, as that is what can easily be read from
   * the stack. This is not a problem except for a few cases where the return
   * address is inside a different symbol than the call address.
   */
  #define CALL_INSTRUCTION_FROM_RETURN_ADDRESS(A) (DETAG_INSTRUCTION_ADDRESS((A)) - 1)
  
  
  uintptr_t kssymbolicator_callInstructionAddress(const uintptr_t returnAddress)
  {
      return CALL_INSTRUCTION_FROM_RETURN_ADDRESS(returnAddress);
  }
  
  bool kssymbolicator_symbolicate(KSStackCursor *cursor)
  {
      Dl_info symbolsBuffer;
      if(ksdl_dladdr(CALL_INSTRUCTION_FROM_RETURN_ADDRESS(cursor->stackEntry.address), &symbolsBuffer))
      {
          cursor->stackEntry.imageAddress = (uintptr_t)symbolsBuffer.dli_fbase;
          cursor->stackEntry.imageName = symbolsBuffer.dli_fname;
          cursor->stackEntry.symbolAddress = (uintptr_t)symbolsBuffer.dli_saddr;
          cursor->stackEntry.symbolName = symbolsBuffer.dli_sname;
          return true;
      }
      
      cursor->stackEntry.imageAddress = 0;
      cursor->stackEntry.imageName = 0;
      cursor->stackEntry.symbolAddress = 0;
      cursor->stackEntry.symbolName = 0;
      return false;
  }
  