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// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// 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.
// * Neither the name of Google Inc. nor the names of its
// 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
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// 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
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ---
// Author: Sanjay Ghemawat
//
// Portable implementation - just use glibc
//
// Note: The glibc implementation may cause a call to malloc.
// This can cause a deadlock in HeapProfiler.
#include <execinfo.h>
#include <stdlib.h>
#include "google/stacktrace.h"
// If you change this function, also change GetStackFrames below.
int GetStackTrace(void** result, int max_depth, int skip_count) {
static const int kStackLength = 64;
void * stack[kStackLength];
int size;
size = backtrace(stack, kStackLength);
skip_count++; // we want to skip the current frame as well
int result_count = size - skip_count;
if (result_count < 0)
result_count = 0;
if (result_count > max_depth)
result_count = max_depth;
for (int i = 0; i < result_count; i++)
result[i] = stack[i + skip_count];
return result_count;
}
// If you change this function, also change GetStackTrace above:
//
// This GetStackFrames routine shares a lot of code with GetStackTrace
// above. This code could have been refactored into a common routine,
// and then both GetStackTrace/GetStackFrames could call that routine.
// There are two problems with that:
//
// (1) The performance of the refactored-code suffers substantially - the
// refactored needs to be able to record the stack trace when called
// from GetStackTrace, and both the stack trace and stack frame sizes,
// when called from GetStackFrames - this introduces enough new
// conditionals that GetStackTrace performance can degrade by as much
// as 50%.
//
// (2) Whether the refactored routine gets inlined into GetStackTrace and
// GetStackFrames depends on the compiler, and we can't guarantee the
// behavior either-way, even with "__attribute__ ((always_inline))"
// or "__attribute__ ((noinline))". But we need this guarantee or the
// frame counts may be off by one.
//
// Both (1) and (2) can be addressed without this code duplication, by
// clever use of template functions, and by defining GetStackTrace and
// GetStackFrames as macros that expand to these template functions.
// However, this approach comes with its own set of problems - namely,
// macros and preprocessor trouble - for example, if GetStackTrace
// and/or GetStackFrames is ever defined as a member functions in some
// class, we are in trouble.
int GetStackFrames(void** pcs, int* sizes, int max_depth, int skip_count) {
static const int kStackLength = 64;
void * stack[kStackLength];
int size;
size = backtrace(stack, kStackLength);
skip_count++; // we want to skip the current frame as well
int result_count = size - skip_count;
if (result_count < 0)
result_count = 0;
if (result_count > max_depth)
result_count = max_depth;
for (int i = 0; i < result_count; i++)
pcs[i] = stack[i + skip_count];
// No implementation for finding out the stack frame sizes yet.
memset(sizes, 0, sizeof(*sizes) * result_count);
return result_count;
}
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