// Copyright (c) 2005 - 2007, Google Inc.

// All rights reserved.

//

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// modification, are permitted provided that the following conditions are

// met:

//

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// notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

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// contributors may be used to endorse or promote products derived from

// this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

//

// Author: Arun Sharma

//

// Produce stack trace using libgcc

extern "C" {

#include <stdlib.h> // for NULL

#include <unwind.h> // ABI defined unwinder

}

#include "stacktrace.h"

_START_GOOGLE_NAMESPACE_

typedef struct {

  void **result;

  int max_depth;

  int skip_count;

  int count;

} trace_arg_t;

// Workaround for the malloc() in _Unwind_Backtrace() issue.

static _Unwind_Reason_Code nop_backtrace(struct _Unwind_Context *uc, void *opq) {

  return _URC_NO_REASON;

}

// This code is not considered ready to run until

// static initializers run so that we are guaranteed

// that any malloc-related initialization is done.

static bool ready_to_run = false;

class StackTraceInit {

 public:

   StackTraceInit() {

     // Extra call to force initialization

     _Unwind_Backtrace(nop_backtrace, NULL);

     ready_to_run = true;

   }

};

static StackTraceInit module_initializer;  // Force initialization

static _Unwind_Reason_Code GetOneFrame(struct _Unwind_Context *uc, void *opq) {

  trace_arg_t *targ = (trace_arg_t *) opq;

  if (targ->skip_count > 0) {

    targ->skip_count--;

  } else {

    targ->result[targ->count++] = (void *) _Unwind_GetIP(uc);

  }

  if (targ->count == targ->max_depth)

    return _URC_END_OF_STACK;

  return _URC_NO_REASON;

}

// If you change this function, also change GetStackFrames below.

int GetStackTrace(void** result, int max_depth, int skip_count) {

  if (!ready_to_run)

    return 0;

  trace_arg_t targ;

  skip_count += 1;         // Do not include the "GetStackTrace" frame

  targ.result = result;

  targ.max_depth = max_depth;

  targ.skip_count = skip_count;

  targ.count = 0;

  _Unwind_Backtrace(GetOneFrame, &targ);

  return targ.count;

}

_END_GOOGLE_NAMESPACE_