Upstream android debug and log related files

base/debug/stack_trace_android.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/debug/stack_trace.h"
+
+#include <signal.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "base/logging.h"
+
+namespace base {
+namespace debug {
+
+StackTrace::StackTrace() {
+}
+
+StackTrace::~StackTrace() {
+}
+
+const void* const* StackTrace::Addresses(size_t* count) const {
+  NOTIMPLEMENTED();
+  return NULL;
+}
+
+// Sends fake SIGSTKFLT signals to let the Android linker and debuggerd dump
+// stack. See inlined comments and Android bionic/linker/debugger.c and
+// system/core/debuggerd/debuggerd.c for details.
+void StackTrace::PrintBacktrace() const {
+  // Get the current handler of SIGSTKFLT for later use.
+  sighandler_t sig_handler = signal(SIGSTKFLT, SIG_DFL);
+  signal(SIGSTKFLT, sig_handler);
+
+  // The Android linker will handle this signal and send a stack dumping request
+  // to debuggerd which will ptrace_attach this process. Before returning from
+  // the signal handler, the linker sets the signal handler to SIG_IGN.
+  kill(gettid(), SIGSTKFLT);
+
+  // Because debuggerd will wait for the process to be stopped by the actual
+  // signal in crashing scenarios, signal is sent again to met the expectation.
+  // Debuggerd will dump stack into the system log and /data/tombstones/ files.
+  // NOTE: If this process runs in the interactive shell, it will be put
+  // in the background. To resume it in the foreground, use 'fg' command.
+  kill(gettid(), SIGSTKFLT);
+
+  // Restore the signal handler so that this method can work the next time.
+  signal(SIGSTKFLT, sig_handler);
+}
+
+void StackTrace::OutputToStream(std::ostream* os) const {
+  NOTIMPLEMENTED();
+}
+
+}  // namespace debug
+}  // namespace base