breakpad/src/processor/logging.h

// Copyright (c) 2007, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// logging.h: Breakpad logging
//
// Breakpad itself uses Breakpad logging with statements of the form:
//   BPLOG(severity) << "message";
// severity may be INFO, ERROR, or other values defined in this file.
//
// BPLOG is an overridable macro so that users can customize Breakpad's
// logging.  Left at the default, logging messages are sent to stderr along
// with a timestamp and the source code location that produced a message.
// The streams may be changed by redefining BPLOG_*_STREAM, the logging
// behavior may be changed by redefining BPLOG_*, and the entire logging
// system may be overridden by redefining BPLOG(severity).  These
// redefinitions may be passed to the preprocessor as a command-line flag
// (-D).
//
// If an additional header is required to override Breakpad logging, it can
// be specified by the BP_LOGGING_INCLUDE macro.  If defined, this header
// will #include the header specified by that macro.
//
// Author: Mark Mentovai

#ifndef PROCESSOR_LOGGING_H__
#define PROCESSOR_LOGGING_H__

#include <iostream>
#include <string>

#include "google_breakpad/common/breakpad_types.h"

#ifdef BP_LOGGING_INCLUDE
#include BP_LOGGING_INCLUDE
#endif  // BP_LOGGING_INCLUDE

namespace google_breakpad {

class LogStream {
 public:
  enum Severity {
    SEVERITY_INFO,
    SEVERITY_ERROR,
  };

  // Begin logging a message to the stream identified by |stream|, at the
  // indicated severity.  The file and line parameters should be set so as to
  // identify the line of source code that is producing a message.
  LogStream(std::ostream &stream, Severity severity,
            const char *file, int line);

  // Finish logging by printing a newline and flushing the output stream.
  ~LogStream();

  template<typename T> std::ostream& operator<<(const T &t) {
    return stream_ << t;
  }

 private:
  std::ostream &stream_;

  // Disallow copy constructor and assignment operator
  explicit LogStream(const LogStream &that);
  void operator=(const LogStream &that);
};

// This class is used to explicitly ignore values in the conditional logging
// macros.  This avoids compiler warnings like "value computed is not used"
// and "statement has no effect".
class LogMessageVoidify {
 public:
  LogMessageVoidify() {}

  // This has to be an operator with a precedence lower than << but higher
  // than ?:
  void operator&(std::ostream &) {}
};

// Returns number formatted as a hexadecimal string, such as "0x7b".
std::string HexString(u_int32_t number);
std::string HexString(u_int64_t number);
std::string HexString(int number);

// Returns the error code as set in the global errno variable, and sets
// error_string, a required argument, to a string describing that error
// code.
int ErrnoString(std::string *error_string);

}  // namespace google_breakpad

#ifndef BPLOG
#define BPLOG(severity) BPLOG_ ## severity
#endif  // BPLOG

#ifndef BPLOG_INFO
#ifndef BPLOG_INFO_STREAM
#define BPLOG_INFO_STREAM std::clog
#endif  // BPLOG_INFO_STREAM
#define BPLOG_INFO LogStream(BPLOG_INFO_STREAM, LogStream::SEVERITY_INFO, \
                             __FILE__, __LINE__)
#endif  // BPLOG_INFO

#ifndef BPLOG_ERROR
#ifndef BPLOG_ERROR_STREAM
#define BPLOG_ERROR_STREAM std::cerr
#endif  // BPLOG_ERROR_STREAM
#define BPLOG_ERROR LogStream(BPLOG_ERROR_STREAM, LogStream::SEVERITY_ERROR, \
                              __FILE__, __LINE__)
#endif  // BPLOG_ERROR

#define BPLOG_IF(severity, condition) \
    !(condition) ? (void) 0 : LogMessageVoidify() & BPLOG(severity)

#endif  // PROCESSOR_LOGGING_H__