libutil/Log.h

   1 #ifndef REMOTE_UTIL_LOG_H
   2 #define REMOTE_UTIL_LOG_H
   3
   4 #include <stdarg.h>
   5 #include <stdio.h>
   6 #include <syslog.h>
   7
   8 namespace remote { namespace util {
   9
  10 class Log {
  11         public:
  12                 /** Log level specifiers
  13                  *
  14                  * The following log levels can be used to specify the default
  15                  * log level when opening a log. They are listed in the order
  16                  * of priority starting with the most important. When
  17                  * specifying the log level, messages with higher priorities
  18                  * are automatically included, e.g. Log::INFO will include
  19                  * Log::ERROR and Log::FATAL.
  20                  *
  21                  * The specifiers all maps internally to syslog priorities as
  22                  * defined in <syslog.h>.
  23                  */
  24                 enum {
  25                         FATAL = LOG_EMERG,
  26                         ERROR = LOG_ERR,
  27                         WARN  = LOG_WARNING,
  28                         INFO  = LOG_INFO,
  29                         DEBUG = LOG_DEBUG,
  30                 };
  31
  32                 /** Syslog specifier
  33                  *
  34                  * May be passed when opening a log, to specify that
  35                  * syslog should be used. E.g.:
  36                  *
  37                  *      Log::open("remote-mch", Log::INFO, Log::SYSLOG);
  38                  */
  39                 static const FILE *SYSLOG;
  40
  41                 /** Setup logging
  42                  *
  43                  * Configures the various logging options and prepares
  44                  * for future calls to redirect messages to the
  45                  * requested place.
  46                  *
  47                  * The log file is an ordinary file handle. It should be
  48                  * a file opened in append mode. To use syslog, pass NULL.
  49                  * The default is to use stdout.
  50                  *
  51                  * @param ident         A unique log identifier
  52                  * @param level         The default log level, messages
  53                  *                      with log level of lower importance
  54                  *                      than this will be discarded.
  55                  * @param file          The log file handle.
  56                  */
  57                 static void open(const char *ident, int level = Log::INFO,
  58                                  const FILE *file = stdout);
  59
  60                 /** Fatal error message
  61                  *
  62                  * An emergency condition occurred rendering the system
  63                  * unusable.
  64                  */
  65                 static void fatal(const char *format, ...);
  66
  67                 /** Error message
  68                  *
  69                  * An error condition occurred.
  70                  */
  71                 static void error(const char *format, ...);
  72
  73                 /** Warning message
  74                  *
  75                  * An warning condition occurred.
  76                  */
  77                 static void warn(const char *format, ...);
  78
  79                 /** Informational message
  80                  *
  81                  * A normal and non-significant condition occurred.
  82                  */
  83                 static void info(const char *format, ...);
  84
  85                 /** Debug message
  86                  *
  87                  * For logging occurrences relevant during debuging.
  88                  */
  89                 static void debug(const char *format, ...);
  90
  91         private:
  92                 static void put(int priority, const char *format, va_list params);
  93                 static const char *ident;
  94                 static const FILE *file;
  95                 static int level;
  96
  97                 static inline bool use_syslog()
  98                 {
  99                         return Log::file == SYSLOG;
 100                 }
 101
 102                 /* This might be a bad hardcoded way to discard messages of
 103                  * less importance. However, the BSD syslog.h file used by
 104                  * glibc states that EMERG < ERR < WARNING < INFO < DEBUG. */
 105                 static inline bool ignore(int priority)
 106                 {
 107                         return priority > Log::level;
 108                 }
 109 };
 110
 111 }}
 112
 113 #endif