stacktrace/detail/collect_unwind.ipp

0001 // Copyright Antony Polukhin, 2016-2023.
0002 //
0003 // Distributed under the Boost Software License, Version 1.0. (See
0004 // accompanying file LICENSE_1_0.txt or copy at
0005 // http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #ifndef BOOST_STACKTRACE_DETAIL_COLLECT_UNWIND_IPP
0008 #define BOOST_STACKTRACE_DETAIL_COLLECT_UNWIND_IPP
0009
0010 #include <boost/config.hpp>
0011 #ifdef BOOST_HAS_PRAGMA_ONCE
0012 #   pragma once
0013 #endif
0014
0015 #include <boost/stacktrace/safe_dump_to.hpp>
0016
0017 // On iOS 32-bit ARM architecture _Unwind_Backtrace function doesn't exist, symbol is undefined.
0018 // Forcing libc backtrace() function usage.
0019 #include <boost/predef.h>
0020 #if defined(BOOST_OS_IOS_AVAILABLE) && defined(BOOST_ARCH_ARM_AVAILABLE) && BOOST_VERSION_NUMBER_MAJOR(BOOST_ARCH_ARM) < 8
0021 #define BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION
0022 #endif
0023
0024 #if defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
0025 #include <execinfo.h>
0026 #include <algorithm>
0027 #else
0028 #include <unwind.h>
0029 #endif
0030 #include <cstdio>
0031
0032 #if !defined(_GNU_SOURCE) && !defined(BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED) && !defined(BOOST_WINDOWS)
0033 #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`."
0034 #endif
0035
0036 namespace boost { namespace stacktrace { namespace detail {
0037
0038 #if !defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
0039 struct unwind_state {
0040     std::size_t frames_to_skip;
0041     native_frame_ptr_t* current;
0042     native_frame_ptr_t* end;
0043 };
0044
0045 inline _Unwind_Reason_Code unwind_callback(::_Unwind_Context* context, void* arg) {
0046     // Note: do not write `::_Unwind_GetIP` because it is a macro on some platforms.
0047     // Use `_Unwind_GetIP` instead!
0048     unwind_state* const state = static_cast<unwind_state*>(arg);
0049     if (state->frames_to_skip) {
0050         --state->frames_to_skip;
0051         return _Unwind_GetIP(context) ? ::_URC_NO_REASON : ::_URC_END_OF_STACK;
0052     }
0053
0054     *state->current =  reinterpret_cast<native_frame_ptr_t>(
0055         _Unwind_GetIP(context)
0056     );
0057
0058     ++state->current;
0059     if (!*(state->current - 1) || state->current == state->end) {
0060         return ::_URC_END_OF_STACK;
0061     }
0062     return ::_URC_NO_REASON;
0063 }
0064 #endif //!defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
0065
0066 std::size_t this_thread_frames::collect(native_frame_ptr_t* out_frames, std::size_t max_frames_count, std::size_t skip) noexcept {
0067     std::size_t frames_count = 0;
0068     if (!max_frames_count) {
0069         return frames_count;
0070     }
0071     skip += 1;
0072
0073 #if defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
0074     // According to https://opensource.apple.com/source/Libc/Libc-1272.200.26/gen/backtrace.c.auto.html
0075     // it looks like the `::backtrace` is async signal safe.
0076     frames_count = static_cast<size_t>(::backtrace(const_cast<void **>(out_frames), static_cast<int>(max_frames_count)));
0077
0078     // NOTE: There is no way to pass "skip" count to backtrace function so we need to perform left shift operation.
0079     // If number of elements in result backtrace is >= max_frames_count then "skip" elements are wasted.
0080     if (frames_count && skip) {
0081         if (skip >= frames_count) {
0082             frames_count = 0;
0083         } else {
0084             std::copy(out_frames + skip, out_frames + frames_count, out_frames);
0085             frames_count -= skip;
0086         }
0087     }
0088 #else
0089     boost::stacktrace::detail::unwind_state state = { skip, out_frames, out_frames + max_frames_count };
0090     ::_Unwind_Backtrace(&boost::stacktrace::detail::unwind_callback, &state);
0091     frames_count = state.current - out_frames;
0092 #endif //defined(BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION)
0093
0094     if (frames_count && out_frames[frames_count - 1] == 0) {
0095         -- frames_count;
0096     }
0097
0098     return frames_count;
0099 }
0100
0101
0102 }}} // namespace boost::stacktrace::detail
0103
0104 #undef BOOST_STACKTRACE_USE_LIBC_BACKTRACE_FUNCTION
0105
0106 #endif // BOOST_STACKTRACE_DETAIL_COLLECT_UNWIND_IPP