2 * Copyright 2017 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.
17 #include <folly/experimental/symbolizer/StackTrace.h>
19 // Must be first to ensure that UNW_LOCAL_ONLY is defined
20 #define UNW_LOCAL_ONLY 1
21 #include <libunwind.h>
24 namespace symbolizer {
26 ssize_t getStackTrace(uintptr_t* addresses, size_t maxAddresses) {
28 sizeof(uintptr_t) == sizeof(void*), "uinptr_t / pointer size mismatch");
29 // The libunwind documentation says that unw_backtrace is async-signal-safe
30 // but, as of libunwind 1.0.1, it isn't (tdep_trace allocates memory on
32 int r = unw_backtrace(reinterpret_cast<void**>(addresses), maxAddresses);
33 return r < 0 ? -1 : r;
37 inline bool getFrameInfo(unw_cursor_t* cursor, uintptr_t& ip) {
39 if (unw_get_reg(cursor, UNW_REG_IP, &uip) < 0) {
42 int r = unw_is_signal_frame(cursor);
46 // Use previous instruction in normal (call) frames (because the
47 // return address might not be in the same function for noreturn functions)
48 // but not in signal frames.
54 ssize_t getStackTraceSafe(uintptr_t* addresses, size_t maxAddresses) {
55 if (maxAddresses == 0) {
58 unw_context_t context;
59 if (unw_getcontext(&context) < 0) {
63 if (unw_init_local(&cursor, &context) < 0) {
66 if (!getFrameInfo(&cursor, *addresses)) {
71 for (; count != maxAddresses; ++count, ++addresses) {
72 int r = unw_step(&cursor);
79 if (!getFrameInfo(&cursor, *addresses)) {
85 } // namespace symbolizer