zircon/system/ulib/syslog/fx_logger.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef ZIRCON_SYSTEM_ULIB_SYSLOG_FX_LOGGER_H_
#define ZIRCON_SYSTEM_ULIB_SYSLOG_FX_LOGGER_H_

#include <lib/syslog/logger.h>
#include <lib/zx/process.h>
#include <lib/zx/socket.h>
#include <lib/zx/thread.h>

#include <atomic>

#include <fbl/mutex.h>
#include <fbl/string.h>
#include <fbl/unique_fd.h>
#include <fbl/vector.h>

namespace {

zx_koid_t GetKoid(zx_handle_t handle) {
  zx_info_handle_basic_t info;
  zx_status_t status =
      zx_object_get_info(handle, ZX_INFO_HANDLE_BASIC, &info, sizeof(info), nullptr, nullptr);
  return status == ZX_OK ? info.koid : ZX_KOID_INVALID;
}

zx_koid_t GetCurrentProcessKoid() {
  auto koid = GetKoid(zx_process_self());
  ZX_DEBUG_ASSERT(koid != ZX_KOID_INVALID);
  return koid;
}

}  // namespace

struct fx_logger {
 public:
  // If tags or ntags are out of bound, this constructor will not fail but it
  // will not store all the tags and global tag behaviour would be undefined.
  // So they should be validated before calling this constructor.
  fx_logger(const fx_logger_config_t* config) {
    pid_ = GetCurrentProcessKoid();
    dropped_logs_.store(0, std::memory_order_relaxed);
    Reconfigure(config);
    if (GetLogConnectionStatus() == ZX_ERR_BAD_STATE) {
      ActivateFallback(-1);
    }
  }

  ~fx_logger() = default;

  zx_status_t VLogWrite(fx_log_severity_t severity, const char* tag, const char* format,
                        va_list args, const char* file = nullptr, uint32_t line = 0) {
    return VLogWrite(severity, tag, file, line, format, args, true);
  }

  zx_status_t LogWrite(fx_log_severity_t severity, const char* tag, const char* msg,
                       const char* file = nullptr, uint32_t line = 0) {
    va_list empty_args;
    return VLogWrite(severity, tag, file, line, msg, empty_args, false);
  }

  zx_status_t SetSeverity(fx_log_severity_t log_severity) {
    if (log_severity > FX_LOG_FATAL) {
      return ZX_ERR_INVALID_ARGS;
    }
    severity_.store(log_severity, std::memory_order_relaxed);
    return ZX_OK;
  }

  fx_log_severity_t GetSeverity() { return severity_.load(std::memory_order_relaxed); }

  void ActivateFallback(int fallback_fd);

  zx_status_t Reconfigure(const fx_logger_config_t* config);

  zx_status_t GetLogConnectionStatus();

  // Set the log connection for this logger using a handle which
  // is presumed to come from a socket connection with the logging
  // service.
  void SetLogConnection(zx_handle_t handle);

 private:
  zx_status_t VLogWrite(fx_log_severity_t severity, const char* tag, const char* file,
                        uint32_t line, const char* format, va_list args, bool perform_format);

  zx_status_t VLogWriteToSocket(fx_log_severity_t severity, const char* tag, const char* file,
                                uint32_t line, const char* msg, va_list args, bool perform_format);

  zx_status_t VLogWriteToFd(int fd, fx_log_severity_t severity, const char* tag, const char* file,
                            uint32_t line, const char* msg, va_list args, bool perform_format);

  zx_status_t SetTags(const char* const* tags, size_t ntags);

  zx_koid_t pid_;
  std::atomic<fx_log_severity_t> severity_;
  std::atomic<uint32_t> dropped_logs_;
  std::atomic<int> logger_fd_ = -1;
  zx::socket socket_;
  fbl::Vector<fbl::String> tags_;

  // This field is just used to close fd when
  // logger object goes out of scope
  fbl::unique_fd fd_to_close_;

  // string representation to print in fallback mode
  fbl::String tagstr_;

  fbl::Mutex logger_mutex_;
};

#endif  // ZIRCON_SYSTEM_ULIB_SYSLOG_FX_LOGGER_H_