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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 {
     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 
     53 namespace base {
     54 namespace debug {
     55 
     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 
     68 StackTrace::StackTrace() {
     69   StackCrawlState state(reinterpret_cast<uintptr_t*>(trace_), kMaxTraces);
     70   _Unwind_Backtrace(&TraceStackFrame, &state);
     71   count_ = state.frame_count;
     72 }
     73 
     74 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).
     82 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