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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 <string.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;
+}