debugd/src/perf_tool.cc

// Copyright (c) 2013 The Chromium OS 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 "debugd/src/perf_tool.h"

#include <base/strings/string_number_conversions.h>
#include <base/strings/string_split.h>
#include <base/strings/string_util.h>
#include <sys/utsname.h>

#include <algorithm>
#include <map>

#include "debugd/src/process_with_output.h"

using base::StringPrintf;

namespace debugd {

namespace {

const char kUnsupportedPerfToolErrorName[] =
    "org.chromium.debugd.error.UnsupportedPerfTool";

// Location of quipper on ChromeOS.
const char kQuipperLocation[] = "/usr/bin/quipper";

enum PerfSubcommand {
  PERF_COMMAND_RECORD,
  PERF_COMMAND_STAT,
  PERF_COMMAND_MEM,
  PERF_COMMAND_UNSUPPORTED,
};

// Returns one of the above enums given an vector of perf arguments, starting
// with "perf" itself in |args[0]|.
PerfSubcommand GetPerfSubcommandType(const std::vector<std::string>& args) {
  if (args[0] == "perf" && args.size() > 1) {
    if (args[1] == "record")
      return PERF_COMMAND_RECORD;
    if (args[1] == "stat")
      return PERF_COMMAND_STAT;
    if (args[1] == "mem")
      return PERF_COMMAND_MEM;
  }

  return PERF_COMMAND_UNSUPPORTED;
}

}  // namespace

PerfTool::PerfTool() {}

int PerfTool::GetPerfOutput(const uint32_t& duration_secs,
                            const std::vector<std::string>& perf_args,
                            std::vector<uint8_t>* perf_data,
                            std::vector<uint8_t>* perf_stat,
                            DBus::Error* error) {
  PerfSubcommand subcommand = GetPerfSubcommandType(perf_args);
  if (subcommand == PERF_COMMAND_UNSUPPORTED) {
    error->set(kUnsupportedPerfToolErrorName,
               "perf_args must begin with {\"perf\", \"record\"}, "
               " {\"perf\", \"stat\"}, or {\"perf\", \"mem\"}");
    return -1;
  }

  std::string output_string;
  int result =
      GetPerfOutputHelper(duration_secs, perf_args, error, &output_string);

  switch (subcommand) {
  case PERF_COMMAND_RECORD:
  case PERF_COMMAND_MEM:
    perf_data->assign(output_string.begin(), output_string.end());
    break;
  case PERF_COMMAND_STAT:
    perf_stat->assign(output_string.begin(), output_string.end());
    break;
  default:
    // Discard the output.
    break;
  }

  return result;
}

int PerfTool::GetPerfOutputHelper(const uint32_t& duration_secs,
                                  const std::vector<std::string>& perf_args,
                                  DBus::Error* error,
                                  std::string* data_string) {
  // This whole method is synchronous, so we create a subprocess, let it run to
  // completion, then gather up its output to return it.
  ProcessWithOutput process;
  process.SandboxAs("root", "root");
  if (!process.Init())
    *data_string = "<process init failed>";
  // If you're going to add switches to a command, have a look at the Process
  // interface; there's support for adding options specifically.
  process.AddArg(kQuipperLocation);
  process.AddArg(StringPrintf("%u", duration_secs));
  for (const auto& arg : perf_args) {
    process.AddArg(arg);
  }
  // Run the process to completion. If the process might take a while, you may
  // have to make this asynchronous using .Start().
  int status = process.Run();
  if (status != 0)
    *data_string = StringPrintf("<process exited with status: %d", status);
  process.GetOutput(data_string);

  return status;
}

}  // namespace debugd