2 * Copyright 2017-present Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 #include <folly/experimental/symbolizer/StackTrace.h>
18 // Must be first to ensure that UNW_LOCAL_ONLY is defined
19 #define UNW_LOCAL_ONLY 1
20 #include <libunwind.h>
23 namespace symbolizer {
25 ssize_t getStackTrace(uintptr_t* addresses, size_t maxAddresses) {
27 sizeof(uintptr_t) == sizeof(void*), "uintptr_t / pointer size mismatch");
28 // The libunwind documentation says that unw_backtrace is async-signal-safe
29 // but, as of libunwind 1.0.1, it isn't (tdep_trace allocates memory on
31 int r = unw_backtrace(reinterpret_cast<void**>(addresses), maxAddresses);
32 return r < 0 ? -1 : r;
36 inline bool getFrameInfo(unw_cursor_t* cursor, uintptr_t& ip) {
38 if (unw_get_reg(cursor, UNW_REG_IP, &uip) < 0) {
41 int r = unw_is_signal_frame(cursor);
45 // Use previous instruction in normal (call) frames (because the
46 // return address might not be in the same function for noreturn functions)
47 // but not in signal frames.
53 ssize_t getStackTraceSafe(uintptr_t* addresses, size_t maxAddresses) {
54 if (maxAddresses == 0) {
57 unw_context_t context;
58 if (unw_getcontext(&context) < 0) {
62 if (unw_init_local(&cursor, &context) < 0) {
65 if (!getFrameInfo(&cursor, *addresses)) {
70 for (; count != maxAddresses; ++count, ++addresses) {
71 int r = unw_step(&cursor);
78 if (!getFrameInfo(&cursor, *addresses)) {
84 } // namespace symbolizer