net/test/spawned_test_server/local_test_server_posix.cc

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/test/spawned_test_server/local_test_server.h"

#include <poll.h>
#include <stdint.h>

#include <vector>

#include "base/command_line.h"
#include "base/containers/span.h"
#include "base/files/file_util.h"
#include "base/files/scoped_file.h"
#include "base/logging.h"
#include "base/path_service.h"
#include "base/process/kill.h"
#include "base/process/launch.h"
#include "base/process/process_iterator.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "net/test/python_utils.h"

namespace {

// Helper class used to detect and kill orphaned python test server processes.
// Checks if the command line of a process contains |path_string| (the path
// from which the test server was launched) and |port_string| (the port used by
// the test server), and if the parent pid of the process is 1 (indicating that
// it is an orphaned process).
class OrphanedTestServerFilter : public base::ProcessFilter {
 public:
  OrphanedTestServerFilter(
      const std::string& path_string, const std::string& port_string)
      : path_string_(path_string),
        port_string_(port_string) {}

  OrphanedTestServerFilter(const OrphanedTestServerFilter&) = delete;
  OrphanedTestServerFilter& operator=(const OrphanedTestServerFilter&) = delete;

  bool Includes(const base::ProcessEntry& entry) const override {
    if (entry.parent_pid() != 1)
      return false;
    bool found_path_string = false;
    bool found_port_string = false;
    for (const auto& cmd_line_arg : entry.cmd_line_args()) {
      if (cmd_line_arg.find(path_string_) != std::string::npos)
        found_path_string = true;
      if (cmd_line_arg.find(port_string_) != std::string::npos)
        found_port_string = true;
    }
    return found_path_string && found_port_string;
  }

 private:
  std::string path_string_;
  std::string port_string_;
};

// Given a file descriptor, reads into |buffer| until it's full or an error has
// been encountered.  Returns true if the read was successful.
bool ReadData(int fd, base::span<uint8_t> buffer) {
  size_t initial_size = buffer.size();
  while (!buffer.empty()) {
    struct pollfd poll_fds[1];

    poll_fds[0].fd = fd;
    poll_fds[0].events = POLLIN | POLLPRI;
    poll_fds[0].revents = 0;

    // Each test itself has its own timeout, so no need to use one here.
    int rv = HANDLE_EINTR(poll(poll_fds, 1, -1));
    if (rv == 0) {
      LOG(ERROR) << "poll() timed out; bytes_read="
                 << (initial_size - buffer.size());
      return false;
    } else if (rv < 0) {
      PLOG(ERROR) << "poll() failed for child file descriptor; bytes_read="
                  << (initial_size - buffer.size());
      return false;
    }

    ssize_t num_bytes = HANDLE_EINTR(read(fd, buffer.data(), buffer.size()));
    if (num_bytes <= 0)
      return false;
    buffer.take_first(static_cast<size_t>(num_bytes));
  }
  return true;
}

}  // namespace

namespace net {

bool LocalTestServer::LaunchPython(
    const base::FilePath& testserver_path,
    const std::vector<base::FilePath>& python_path) {
  base::CommandLine python_command(base::CommandLine::NO_PROGRAM);
  if (!GetPython3Command(&python_command))
    return false;

  python_command.AppendArgPath(testserver_path);
  if (!AddCommandLineArguments(&python_command))
    return false;

  int pipefd[2];
  if (pipe(pipefd) != 0) {
    PLOG(ERROR) << "Could not create pipe.";
    return false;
  }

  // Save the read half. The write half is sent to the child.
  child_fd_.reset(pipefd[0]);
  base::ScopedFD write_closer(pipefd[1]);

  python_command.AppendArg("--startup-pipe=" + base::NumberToString(pipefd[1]));

  // Try to kill any orphaned testserver processes that may be running.
  OrphanedTestServerFilter filter(testserver_path.value(),
                                  base::NumberToString(GetPort()));
  if (!base::KillProcesses("python", -1, &filter)) {
    LOG(WARNING) << "Failed to clean up older orphaned testserver instances.";
  }

  // Launch a new testserver process.
  base::LaunchOptions options;
  SetPythonPathInEnvironment(python_path, &options.environment);

  // Log is useful in the event you want to run a nearby script (e.g. a test) in
  // the same environment as the TestServer.
  LOG(ERROR) << "LaunchPython called with PYTHONPATH = "
             << options.environment["PYTHONPATH"];

  // Set CWD to source root.
  if (!base::PathService::Get(base::DIR_SRC_TEST_DATA_ROOT,
                              &options.current_directory)) {
    LOG(ERROR) << "Failed to get DIR_SRC_TEST_DATA_ROOT";
    return false;
  }

  options.fds_to_remap.emplace_back(pipefd[1], pipefd[1]);
  LOG(ERROR) << "Running: " << python_command.GetCommandLineString();
  process_ = base::LaunchProcess(python_command, options);
  if (!process_.IsValid()) {
    LOG(ERROR) << "Failed to launch " << python_command.GetCommandLineString();
    return false;
  }

  return true;
}

bool LocalTestServer::WaitToStart() {
  base::ScopedFD our_fd(child_fd_.release());

  uint32_t server_data_len = 0;
  if (!ReadData(our_fd.get(), base::byte_span_from_ref(server_data_len))) {
    LOG(ERROR) << "Could not read server_data_len";
    return false;
  }
  std::string server_data(server_data_len, '\0');
  if (!ReadData(our_fd.get(), base::as_writable_byte_span(server_data))) {
    LOG(ERROR) << "Could not read server_data (" << server_data_len
               << " bytes)";
    return false;
  }

  int port;
  if (!SetAndParseServerData(server_data, &port)) {
    LOG(ERROR) << "Could not parse server_data: " << server_data;
    return false;
  }
  SetPort(port);

  return true;
}

}  // namespace net