1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/debug/stack_trace.h"
6
7#include <android/log.h>
8#include <unwind.h>
9
10#include "base/debug/proc_maps_linux.h"
11#include "base/strings/stringprintf.h"
12#include "base/threading/thread_restrictions.h"
13
14#ifdef __LP64__
15#define FMT_ADDR  "0x%016lx"
16#else
17#define FMT_ADDR  "0x%08x"
18#endif
19
20namespace {
21
22struct StackCrawlState {
23  StackCrawlState(uintptr_t* frames, size_t max_depth)
24      : frames(frames),
25        frame_count(0),
26        max_depth(max_depth),
27        have_skipped_self(false) {}
28
29  uintptr_t* frames;
30  size_t frame_count;
31  size_t max_depth;
32  bool have_skipped_self;
33};
34
35_Unwind_Reason_Code TraceStackFrame(_Unwind_Context* context, void* arg) {
36  StackCrawlState* state = static_cast<StackCrawlState*>(arg);
37  uintptr_t ip = _Unwind_GetIP(context);
38
39  // The first stack frame is this function itself.  Skip it.
40  if (ip != 0 && !state->have_skipped_self) {
41    state->have_skipped_self = true;
42    return _URC_NO_REASON;
43  }
44
45  state->frames[state->frame_count++] = ip;
46  if (state->frame_count >= state->max_depth)
47    return _URC_END_OF_STACK;
48  return _URC_NO_REASON;
49}
50
51}  // namespace
52
53namespace base {
54namespace debug {
55
56bool EnableInProcessStackDumping() {
57  // When running in an application, our code typically expects SIGPIPE
58  // to be ignored.  Therefore, when testing that same code, it should run
59  // with SIGPIPE ignored as well.
60  // TODO(phajdan.jr): De-duplicate this SIGPIPE code.
61  struct sigaction action;
62  memset(&action, 0, sizeof(action));
63  action.sa_handler = SIG_IGN;
64  sigemptyset(&action.sa_mask);
65  return (sigaction(SIGPIPE, &action, NULL) == 0);
66}
67
68StackTrace::StackTrace() {
69  StackCrawlState state(reinterpret_cast<uintptr_t*>(trace_), kMaxTraces);
70  _Unwind_Backtrace(&TraceStackFrame, &state);
71  count_ = state.frame_count;
72}
73
74void StackTrace::Print() const {
75  std::string backtrace = ToString();
76  __android_log_write(ANDROID_LOG_ERROR, "chromium", backtrace.c_str());
77}
78
79// NOTE: Native libraries in APKs are stripped before installing. Print out the
80// relocatable address and library names so host computers can use tools to
81// symbolize and demangle (e.g., addr2line, c++filt).
82void StackTrace::OutputToStream(std::ostream* os) const {
83  std::string proc_maps;
84  std::vector<MappedMemoryRegion> regions;
85  // Allow IO to read /proc/self/maps. Reading this file doesn't hit the disk
86  // since it lives in procfs, and this is currently used to print a stack trace
87  // on fatal log messages in debug builds only. If the restriction is enabled
88  // then it will recursively trigger fatal failures when this enters on the
89  // UI thread.
90  base::ThreadRestrictions::ScopedAllowIO allow_io;
91  if (!ReadProcMaps(&proc_maps)) {
92    __android_log_write(
93        ANDROID_LOG_ERROR, "chromium", "Failed to read /proc/self/maps");
94  } else if (!ParseProcMaps(proc_maps, &regions)) {
95    __android_log_write(
96        ANDROID_LOG_ERROR, "chromium", "Failed to parse /proc/self/maps");
97  }
98
99  for (size_t i = 0; i < count_; ++i) {
100    // Subtract one as return address of function may be in the next
101    // function when a function is annotated as noreturn.
102    uintptr_t address = reinterpret_cast<uintptr_t>(trace_[i]) - 1;
103
104    std::vector<MappedMemoryRegion>::iterator iter = regions.begin();
105    while (iter != regions.end()) {
106      if (address >= iter->start && address < iter->end &&
107          !iter->path.empty()) {
108        break;
109      }
110      ++iter;
111    }
112
113    *os << base::StringPrintf("#%02zd " FMT_ADDR " ", i, address);
114
115    if (iter != regions.end()) {
116      uintptr_t rel_pc = address - iter->start + iter->offset;
117      const char* path = iter->path.c_str();
118      *os << base::StringPrintf("%s+" FMT_ADDR, path, rel_pc);
119    } else {
120      *os << "<unknown>";
121    }
122
123    *os << "\n";
124  }
125}
126
127}  // namespace debug
128}  // namespace base
129