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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 
20 namespace {
21 
22 struct StackCrawlState {
StackCrawlState__anon8289ec7a0111::StackCrawlState23   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 
TraceStackFrame(_Unwind_Context * context,void * arg)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 
53 namespace base {
54 namespace debug {
55 
EnableInProcessStackDumping()56 bool 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 
StackTrace()68 StackTrace::StackTrace() {
69   StackCrawlState state(reinterpret_cast<uintptr_t*>(trace_), kMaxTraces);
70   _Unwind_Backtrace(&TraceStackFrame, &state);
71   count_ = state.frame_count;
72 }
73 
Print() const74 void 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).
OutputToStream(std::ostream * os) const82 void 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