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// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// 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: Arun Sharma
//
// Produce stack trace using libunwind
#ifndef BASE_STACKTRACE_LIBINWIND_INL_H_
#define BASE_STACKTRACE_LIBINWIND_INL_H_
// Note: this file is included into stacktrace.cc more than once.
// Anything that should only be defined once should be here:
// We only need local unwinder.
#define UNW_LOCAL_ONLY
extern "C" {
#include <assert.h>
#include <string.h> // for memset()
#include <libunwind.h>
}
#include "gperftools/stacktrace.h"
#include "base/logging.h"
// Sometimes, we can try to get a stack trace from within a stack
// trace, because libunwind can call mmap (maybe indirectly via an
// internal mmap based memory allocator), and that mmap gets trapped
// and causes a stack-trace request. If were to try to honor that
// recursive request, we'd end up with infinite recursion or deadlock.
// Luckily, it's safe to ignore those subsequent traces. In such
// cases, we return 0 to indicate the situation.
static __thread int recursive;
#if defined(TCMALLOC_ENABLE_UNWIND_FROM_UCONTEXT) && (defined(__i386__) || defined(__x86_64__)) && defined(__GNU_LIBRARY__)
#define BASE_STACKTRACE_UNW_CONTEXT_IS_UCONTEXT 1
#endif
#endif // BASE_STACKTRACE_LIBINWIND_INL_H_
// Note: this part of the file is included several times.
// Do not put globals below.
// The following 4 functions are generated from the code below:
// GetStack{Trace,Frames}()
// GetStack{Trace,Frames}WithContext()
//
// These functions take the following args:
// void** result: the stack-trace, as an array
// int* sizes: the size of each stack frame, as an array
// (GetStackFrames* only)
// int max_depth: the size of the result (and sizes) array(s)
// int skip_count: how many stack pointers to skip before storing in result
// void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
static int GET_STACK_TRACE_OR_FRAMES {
void *ip;
int n = 0;
unw_cursor_t cursor;
unw_context_t uc;
#if IS_STACK_FRAMES
unw_word_t sp = 0, next_sp = 0;
#endif
if (recursive) {
return 0;
}
++recursive;
#if (IS_WITH_CONTEXT && defined(BASE_STACKTRACE_UNW_CONTEXT_IS_UCONTEXT))
if (ucp) {
uc = *(static_cast<unw_context_t *>(const_cast<void *>(ucp)));
/* this is a bit weird. profiler.cc calls us with signal's ucontext
* yet passing us 2 as skip_count and essentially assuming we won't
* use ucontext. */
/* In order to fix that I'm going to assume that if ucp is
* non-null we're asked to ignore skip_count in case we're
* able to use ucp */
skip_count = 0;
} else {
unw_getcontext(&uc);
skip_count += 2; // Do not include current and parent frame
}
#else
unw_getcontext(&uc);
skip_count += 2; // Do not include current and parent frame
#endif
int ret = unw_init_local(&cursor, &uc);
assert(ret >= 0);
while (skip_count--) {
if (unw_step(&cursor) <= 0) {
goto out;
}
#if IS_STACK_FRAMES
if (unw_get_reg(&cursor, UNW_REG_SP, &next_sp)) {
goto out;
}
#endif
}
while (n < max_depth) {
if (unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip) < 0) {
break;
}
#if IS_STACK_FRAMES
sizes[n] = 0;
#endif
result[n++] = ip;
if (unw_step(&cursor) <= 0) {
break;
}
#if IS_STACK_FRAMES
sp = next_sp;
if (unw_get_reg(&cursor, UNW_REG_SP, &next_sp) , 0) {
break;
}
sizes[n - 1] = next_sp - sp;
#endif
}
out:
--recursive;
return n;
}
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