debuggerd/libdebuggerd/backtrace.cpp

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "DEBUG"

#include "libdebuggerd/backtrace.h"

#include <errno.h>
#include <dirent.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#include <map>
#include <memory>
#include <string>

#include <android-base/unique_fd.h>
#include <log/log.h>
#include <unwindstack/Unwinder.h>

#include "libdebuggerd/types.h"
#include "libdebuggerd/utility.h"

static void dump_process_header(log_t* log, pid_t pid, const char* process_name) {
  time_t t = time(NULL);
  struct tm tm;
  localtime_r(&t, &tm);
  char timestr[64];
  strftime(timestr, sizeof(timestr), "%F %T", &tm);
  _LOG(log, logtype::BACKTRACE, "\n\n----- pid %d at %s -----\n", pid, timestr);

  if (process_name) {
    _LOG(log, logtype::BACKTRACE, "Cmd line: %s\n", process_name);
  }
  _LOG(log, logtype::BACKTRACE, "ABI: '%s'\n", ABI_STRING);
}

static void dump_process_footer(log_t* log, pid_t pid) {
  _LOG(log, logtype::BACKTRACE, "\n----- end %d -----\n", pid);
}

void dump_backtrace_thread(int output_fd, unwindstack::Unwinder* unwinder,
                           const ThreadInfo& thread) {
  log_t log;
  log.tfd = output_fd;
  log.amfd_data = nullptr;

  _LOG(&log, logtype::BACKTRACE, "\n\"%s\" sysTid=%d\n", thread.thread_name.c_str(), thread.tid);

  unwinder->SetRegs(thread.registers.get());
  unwinder->Unwind();
  if (unwinder->NumFrames() == 0) {
    _LOG(&log, logtype::THREAD, "Unwind failed: tid = %d", thread.tid);
    return;
  }

  unwinder->SetDisplayBuildID(true);
  for (size_t i = 0; i < unwinder->NumFrames(); i++) {
    _LOG(&log, logtype::BACKTRACE, "  %s\n", unwinder->FormatFrame(i).c_str());
  }
}

void dump_backtrace(android::base::unique_fd output_fd, unwindstack::Unwinder* unwinder,
                    const std::map<pid_t, ThreadInfo>& thread_info, pid_t target_thread) {
  log_t log;
  log.tfd = output_fd.get();
  log.amfd_data = nullptr;

  auto target = thread_info.find(target_thread);
  if (target == thread_info.end()) {
    ALOGE("failed to find target thread in thread info");
    return;
  }

  dump_process_header(&log, target->second.pid, target->second.process_name.c_str());

  dump_backtrace_thread(output_fd.get(), unwinder, target->second);
  for (const auto& [tid, info] : thread_info) {
    if (tid != target_thread) {
      dump_backtrace_thread(output_fd.get(), unwinder, info);
    }
  }

  dump_process_footer(&log, target->second.pid);
}

void dump_backtrace_header(int output_fd) {
  log_t log;
  log.tfd = output_fd;
  log.amfd_data = nullptr;

  char process_name[128];
  read_with_default("/proc/self/cmdline", process_name, sizeof(process_name), "<unknown>");
  dump_process_header(&log, getpid(), process_name);
}

void dump_backtrace_footer(int output_fd) {
  log_t log;
  log.tfd = output_fd;
  log.amfd_data = nullptr;

  dump_process_footer(&log, getpid());
}