boost/stacktrace/detail/collect_unwind.ipp
// Copyright Antony Polukhin, 2016-2021.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_STACKTRACE_DETAIL_COLLECT_UNWIND_IPP
#define BOOST_STACKTRACE_DETAIL_COLLECT_UNWIND_IPP
#include <boost/config.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
# pragma once
#endif
#include <boost/stacktrace/safe_dump_to.hpp>
// On iOS 32-bit ARM architecture _Unwind_Backtrace function doesn't exist, symbol is undefined.
// Forcing libc backtrace() function usage.
#include <boost/predef.h>
#if defined(BOOST_OS_IOS_AVAILABLE) && defined(BOOST_ARCH_ARM_AVAILABLE) && BOOST_VERSION_NUMBER_MAJOR(BOOST_ARCH_ARM) < 8
#define BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION
#endif
#if defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
#include <execinfo.h>
#include <algorithm>
#else
#include <unwind.h>
#endif
#include <cstdio>
#if !defined(_GNU_SOURCE) && !defined(BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED) && !defined(BOOST_WINDOWS)
#error "Boost.Stacktrace requires `_Unwind_Backtrace` function. Define `_GNU_SOURCE` macro or `BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED` if _Unwind_Backtrace is available without `_GNU_SOURCE`."
#endif
namespace boost { namespace stacktrace { namespace detail {
#if !defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
struct unwind_state {
std::size_t frames_to_skip;
native_frame_ptr_t* current;
native_frame_ptr_t* end;
};
inline _Unwind_Reason_Code unwind_callback(::_Unwind_Context* context, void* arg) {
// Note: do not write `::_Unwind_GetIP` because it is a macro on some platforms.
// Use `_Unwind_GetIP` instead!
unwind_state* const state = static_cast<unwind_state*>(arg);
if (state->frames_to_skip) {
--state->frames_to_skip;
return _Unwind_GetIP(context) ? ::_URC_NO_REASON : ::_URC_END_OF_STACK;
}
*state->current = reinterpret_cast<native_frame_ptr_t>(
_Unwind_GetIP(context)
);
++state->current;
if (!*(state->current - 1) || state->current == state->end) {
return ::_URC_END_OF_STACK;
}
return ::_URC_NO_REASON;
}
#endif //!defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
std::size_t this_thread_frames::collect(native_frame_ptr_t* out_frames, std::size_t max_frames_count, std::size_t skip) BOOST_NOEXCEPT {
std::size_t frames_count = 0;
if (!max_frames_count) {
return frames_count;
}
skip += 1;
#if defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
// According to https://opensource.apple.com/source/Libc/Libc-1272.200.26/gen/backtrace.c.auto.html
// it looks like the `::backtrace` is async signal safe.
frames_count = static_cast<size_t>(::backtrace(const_cast<void **>(out_frames), static_cast<int>(max_frames_count)));
// NOTE: There is no way to pass "skip" count to backtrace function so we need to perform left shift operation.
// If number of elements in result backtrace is >= max_frames_count then "skip" elements are wasted.
if (frames_count && skip) {
if (skip >= frames_count) {
frames_count = 0;
} else {
std::copy(out_frames + skip, out_frames + frames_count, out_frames);
frames_count -= skip;
}
}
#else
boost::stacktrace::detail::unwind_state state = { skip, out_frames, out_frames + max_frames_count };
::_Unwind_Backtrace(&boost::stacktrace::detail::unwind_callback, &state);
frames_count = state.current - out_frames;
#endif //defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
if (frames_count && out_frames[frames_count - 1] == 0) {
-- frames_count;
}
return frames_count;
}
}}} // namespace boost::stacktrace::detail
#undef BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION
#endif // BOOST_STACKTRACE_DETAIL_COLLECT_UNWIND_IPP