base/debug/stack_trace_android.cc

   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 <signal.h>
   8 #include <sys/types.h>
   9 #include <unistd.h>
  10
  11 #include "base/logging.h"
  12
  13 namespace base {
  14 namespace debug {
  15
  16 bool EnableInProcessStackDumping() {
  17   // When running in an application, our code typically expects SIGPIPE
  18   // to be ignored.  Therefore, when testing that same code, it should run
  19   // with SIGPIPE ignored as well.
  20   // TODO(phajdan.jr): De-duplicate this SIGPIPE code.
  21   struct sigaction action;
  22   memset(&action, 0, sizeof(action));
  23   action.sa_handler = SIG_IGN;
  24   sigemptyset(&action.sa_mask);
  25   return (sigaction(SIGPIPE, &action, NULL) == 0);
  26 }
  27
  28 StackTrace::StackTrace() {
  29 }
  30
  31 // Sends fake SIGSTKFLT signals to let the Android linker and debuggerd dump
  32 // stack. See inlined comments and Android bionic/linker/debugger.c and
  33 // system/core/debuggerd/debuggerd.c for details.
  34 void StackTrace::PrintBacktrace() const {
  35   // Get the current handler of SIGSTKFLT for later use.
  36   sighandler_t sig_handler = signal(SIGSTKFLT, SIG_DFL);
  37   signal(SIGSTKFLT, sig_handler);
  38
  39   // The Android linker will handle this signal and send a stack dumping request
  40   // to debuggerd which will ptrace_attach this process. Before returning from
  41   // the signal handler, the linker sets the signal handler to SIG_IGN.
  42   kill(gettid(), SIGSTKFLT);
  43
  44   // Because debuggerd will wait for the process to be stopped by the actual
  45   // signal in crashing scenarios, signal is sent again to met the expectation.
  46   // Debuggerd will dump stack into the system log and /data/tombstones/ files.
  47   // NOTE: If this process runs in the interactive shell, it will be put
  48   // in the background. To resume it in the foreground, use 'fg' command.
  49   kill(gettid(), SIGSTKFLT);
  50
  51   // Restore the signal handler so that this method can work the next time.
  52   signal(SIGSTKFLT, sig_handler);
  53 }
  54
  55 void StackTrace::OutputToStream(std::ostream* os) const {
  56   NOTIMPLEMENTED();
  57 }
  58
  59 }  // namespace debug
  60 }  // namespace base