log.h

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/*_############################################################################
  _## 
  _##  log.h  
  _##
  _##  SNMP++ v3.4
  _##  -----------------------------------------------
  _##  Copyright (c) 2001-2021 Jochen Katz, Frank Fock
  _##
  _##  This software is based on SNMP++2.6 from Hewlett Packard:
  _##  
  _##    Copyright (c) 1996
  _##    Hewlett-Packard Company
  _##  
  _##  ATTENTION: USE OF THIS SOFTWARE IS SUBJECT TO THE FOLLOWING TERMS.
  _##  Permission to use, copy, modify, distribute and/or sell this software 
  _##  and/or its documentation is hereby granted without fee. User agrees 
  _##  to display the above copyright notice and this license notice in all 
  _##  copies of the software and any documentation of the software. User 
  _##  agrees to assume all liability for the use of the software; 
  _##  Hewlett-Packard, Frank Fock, and Jochen Katz make no representations 
  _##  about the suitability of this software for any purpose. It is provided 
  _##  "AS-IS" without warranty of any kind, either express or implied. User 
  _##  hereby grants a royalty-free license to any and all derivatives based
  _##  upon this software code base. 
  _##  
  _##########################################################################*/

#ifndef _SNMP_LOG_H_
#define _SNMP_LOG_H_

#include <libsnmp.h>
#include <snmp_pp/config_snmp_pp.h>
#include <snmp_pp/reentrant.h>

#ifndef WIN32
#include <sys/types.h>
#endif
#include <string.h>


#ifdef SNMP_PP_NAMESPACE
namespace Snmp_pp {
#endif

// Log entry class
#define ERROR_LOG       0x10
#define WARNING_LOG     0x20
#define EVENT_LOG       0x30
#define INFO_LOG        0x40
#define DEBUG_LOG       0x50
#define USER_LOG        0x60

#define LOG_CLASS_MASK  0xF0
#define LOG_LEVEL_MASK  0x0F

#define LOG_TYPES       6

#ifdef _NO_LOGGING
 
#define LOG_BEGIN(name,level) (void)0
#define LOG(item) (void)0
#define LOG_END (void)0

#define LOG_UNUSED(x)

#else

#define LOG_BEGIN(name,level)                                   \
{                                                               \
        if (DefaultLog::log()->log_needed(name,level))          \
        {                                                       \
                DefaultLog::lock();                             \
                DefaultLog::create_log_entry(name,level)

#define LOG(item)       *DefaultLog::log_entry() += item

#define LOG_END                                                 \
                *DefaultLog::log() += DefaultLog::log_entry();  \
                DefaultLog::delete_log_entry();                 \
                DefaultLog::unlock();                           \
        }                                                       \
}                                                               \
(void)0

#define LOG_UNUSED(x) x

#endif


/*--------------------------- class LogEntry --------------------------*/

/**
 * The LogEntry class represents log entries. An instance of LogEntry can be
 * added to a Log. Each LogEntry can be classified into the log classes
 * ERROR_LOG, WARNING_LOG, EVENT_LOG, INFO_LOG, DEBUG_LOG and USER_LOG with up
 * to 16 severity levels. A log entry consists of a descriptor string and
 * optional several string or numeric values.
 *
 * The log class USER_LOG can be used for applications, it is not used
 * within snmp++ and agent++.
 *
 * @note A error log of level 0 will stop program execution!
 *
 * @see Log
 * 
 * @author Frank Fock
 * @author Marty Janzen
 * @version 3.6
 */

class DLLOPT LogEntry {
public:
        /**
         * Constructor with log class and severity level
         * 
         * @param n - The name of the logging module
         * @param t - The type of the log entry. The type is composed 
         *            by a logical OR of the log entry class with a level
         *            of 0 up to 15. 
         * @note A error log of level 0 will stop program execution!
         */  
        LogEntry(const char * const n, unsigned char t) : name(n), type(t), count(0) {}

        /**
         * Virtual destructor.
         */  
        virtual ~LogEntry() {}

        /**
         * Initialize a new log entry, showing timestamp, class, and level.
         */ 
        virtual void init();

        /**
         * Add a numeric value to the log entry.
         *
         * @param l - A numeric value.
         */
        virtual LogEntry& operator+=(const long l);

        /**
         * Add a string value to the log entry.
         *
         * @param s - A string value.
         */
        virtual LogEntry& operator+=(const char* s);

        /**
         * Get the contents of this log entry.
         *
         * @return Current contents of this log entry.
         */ 
        virtual const char* get_value() const { return ""; }

        /**
         * Get the type of this log entry.
         *
         * @return Log entry type.
         * @since 3.6
         */ 
        unsigned char get_type() const { return type; }

        /**
         * Get the class of this log entry.
         *
         * @return Log entry class.
         */ 
        unsigned char get_class() const { return (unsigned char)(type & LOG_CLASS_MASK); }

        /**
         * Get the level of this log entry.
         *
         * @return Log entry level.
         */ 
        unsigned char get_level() const { return (unsigned char)(type & LOG_LEVEL_MASK); }

        /**
         * Get the logger name of this log entry.
         *
         * @return Log entry logger name
         */
        const char * get_name() const { return name; }

protected:
        /**
         * Add a string to the log.
         *
         * @param s - A string value.
         * @return TRUE if the value has been added and FALSE if the log
         *         entry is full.
         */
        virtual bool    add_string(const char* s) = 0;

        /**
         * Add an integer to the log.
         *
         * @param s - An integer value.
         * @return TRUE if the value has been added and FALSE if the log
         *         entry is full.
         */
        virtual bool    add_integer(long s);

        /**
         * Add the current time to the log.
         */
        virtual bool add_timestamp();

protected:
        const char * const      name;
        unsigned char           type;
        int                     count;
};


/*------------------------- class LogEntryImpl ------------------------*/

#define MAX_LOG_SIZE    2550 // increased until debugprintf is not used!

/**
 * The LogEntryImpl class implements a log entry using a dynamically
 * allocated, but fixed-size buffer.
 * @see Log
 * 
 * @author Marty Janzen
 * @version 3.6
 */

class DLLOPT LogEntryImpl : public LogEntry {
public:
        /**
         * Constructor with log class and severity level
         * 
         * @param n - The name of the logging module
         * @param t - The type of the log entry. The type is composed 
         *            by logical or the log entry class with a level
         *            of 0 up to 15. 
         * @note A error log of level 0 will stop program execution!
         */  
        LogEntryImpl(const char * const n, unsigned char t)
                : LogEntry(n, t)
        {
                value = new char[MAX_LOG_SIZE];
                value[0] = '\0';
                ptr = value;
                output_stopped = false;
        }

        /**
         * Destructor.
         */  
        virtual ~LogEntryImpl()
        {
                delete [] value;
        }

        /**
         * Get the contents of this log entry.
         *
         * @return Current contents of this log entry.
         */ 
        virtual const char* get_value() const { return value; }

protected:
        /**
         * Count the bytes left for additional values.
         *
         * @return The number of bytes left in this log entry.
         */  
        unsigned int            bytes_left() 
            { return (unsigned int)(MAX_LOG_SIZE-(ptr-value)-1); }

        /**
         * Add a string to the log.
         *
         * @param s - A string value.
         * @return TRUE if the value has been added and FALSE if the log
         *         entry is full.
         */
        bool            add_string(const char* s);

private:
        char*           value;
        char*           ptr;
        bool            output_stopped;
};


/*--------------------------- class AgentLog --------------------------*/

/**
 * The AgentLog class is an abstract base class representing a log for
 * information that is generated during the run time of an AGENT++
 * SNMP agent.  A derived class only needs to provide appropriate
 * create_log_entry() and operator+= methods.
 * @see LogEntry
 *
 * @author Frank Fock
 * @version 3.6
 */
 
class DLLOPT AgentLog {
public:
        /**
         * Default constructor.
         */ 
        AgentLog();

        /**
         * Virtual destructor.
         */
        virtual ~AgentLog() {}

#ifdef WITH_LOG_PROFILES
        /**
         * Set a bunch of predefined filters for all log classes at once.
         * Only available when built with WITH_LOG_PROFILES
         *
         * @param logprofile - name of a log profile, must be one of
         *  { "off", "quiet", "std", "events", "verbose", "full",
         *    "debug", "schwafel", "original" }
         *  In case a non-existent profile is chosen, "original" is used.
         */
        virtual void    set_profile(const char * const logprofile);
#endif

        /**
         * Set a filter on a specified log class. Only log entries with
         * a level less or equal than the specified level will be logged.
         *
         * @param logclass - A log entry class. @see LogEntry
         * @param filter - A value between 0 and 15.
         */ 
        virtual void    set_filter(int logclass, unsigned char filter);

        /**
         * Gets the log level for the given log class.
         * @return
         *    a unsigned char value between 0 and 15 
         */
        virtual unsigned char get_filter(int logclass) const; 

        /**
         * Create a new LogEntry.
         *
         * @param name - The name of the logging module
         * @param t - The type of the log entry.
         * @return A new instance of LogEntry (or of a derived class).
         */
        virtual LogEntry* create_log_entry(const char * const name, unsigned char t) const = 0;

        /**
         * Add a LogEntry to the receiver Log.
         *
         * @param log - A log entry.
         * @return The receiver log itself.
         */
        virtual AgentLog& operator+=(const LogEntry* log) = 0;

        /**
         * Check whether a logging for the given type of LogEntry
         * has to be done or not.
         *
         * @param t
         *    the type of the log entry. The type is composed 
         *    by logical or the log entry class with a level
         *    of 0 up to 15.
         * @return
         *    TRUE if logging is needed, FALSE otherwise.
         */
        virtual bool    log_needed(const char * const, unsigned char t) const
          { return (logfilter[(t / 16) - 1] != 0xFF) && ((t & LOG_LEVEL_MASK) <= logfilter[(t / 16) - 1]); }

        /**
         * Return the current time as a string.
         * 
         * @param buf
         *    a buffer (of at least 18 characters, for the default method)
         *    into which to place a string containg the current time.
         *    If no buffer is supplied, a static area is used.
         * @return
         *    a string containing the current time. Either the supplied
         *    buffer or the static area.
         */
        virtual const char*     now(char* buf = 0);

        /**
         * Return the current time as a string, using the current
         * default log object.  (For backward compatibility.)
         * @note that the user is responsible for deleting the returned
         * string, using delete [].
         * 
         * @return
         *    a string containg the current time.
         */
        static const char*      get_current_time();

protected:
        unsigned char           logfilter[LOG_TYPES];
        char                    static_buf[18];
};


/*------------------------- class AgentLogImpl ------------------------*/

/**
 * The AgentLogImpl class is an implementation of AgentLog which writes
 * log messages to a file, or to stdout or stderr.
 * @see LogEntry 
 *
 * @author Frank Fock
 * @version 3.5f
 */
 
class DLLOPT AgentLogImpl : public AgentLog {
public:
        /**
         * Default constructor, with optional pointer to an open log file.
         * Log is directed to the file if given, otherwise to stdout
         *
         * @param fp - An open log file.  0 implies stdout.
         */ 
        AgentLogImpl(FILE* fp = stdout);

        /**
         * Constructor with file name of a log file. Log is directed
         * to the given file.
         *
         * @param fname - The file name of a log file.
         */ 
        AgentLogImpl(const char* fname);

        /**
         * Destructor.
         */
        ~AgentLogImpl();

        /**
         * Set destination of logs to a given file.
         * 
         * @param fname - A file name. "" directs logs to stdout.
         */
        void            set_dest(const char* fname);

        /**
         * Set destination of logs to a given file.
         * 
         * @param fp - A pointer to an open file.  0 directs logs to stdout.
         */
        void            set_dest(FILE* fp);

        /**
         * Create a new LogEntry.
         *
         * @param name - The name of the logging module
         * @param t - The type of the log entry.
         * @return A new instance of LogEntry (or of a derived class).
         */
        virtual LogEntry* create_log_entry(const char * const name, unsigned char t) const;

        /**
         * Add a LogEntry to the receiver Log.
         *
         * @param log - A log entry.
         * @return The receiver log itself.
         */
        virtual AgentLog& operator+=(const LogEntry* log);

protected:
        FILE*                   logfile;
        bool                    close_needed;
};


/*--------------------------- class DefaultLog --------------------------*/

/**
 * The DefaultLog class has a static Log member, that is used by the
 * AGENT++ API for logging.
 *
 * @version 3.6
 * @author Frank Fock (singleton pattern -> Philippe Roger)
 */  

class DLLOPT DefaultLog {
public:
        DefaultLog() { }
        ~DefaultLog() { }

        /**
         * Initialize the default logger with the given logging implementation.
         *
         * @note Call cleanup function before the application exits
         * @note The DefaultLog class takes ownership of the pointer. Do
         *       not delete it yourself.
         * @note This method is NOT THREADSAFE. It must be called in main()
         *       before any logging takes place.
         * 
         * @param logger
         *    an AgentLog instance to be used as default logger. A previously
         *    set logger will be deleted.
         */
        static void init(AgentLog* logger) 
          { lock(); if (instance) delete instance; instance = logger; unlock(); }

        /**
         * Initialize the default logger with the given logging implementation
         * if there is currently no logger instance set.
         *
         * @note Call cleanup function before the application exits
         * @note The DefaultLog class takes ownership of the pointer. Do
         *       not delete it yourself.
         * @note This method is THREADSAFE. 
         * 
         * @param logger
         *    an AgentLog instance to be used as default logger.
         * @return
         *    the existing logger (if there was any) or the new logger pointer.
         * @since 3.5.24
         */
        static AgentLog* init_ts(AgentLog* logger = NULL);

        /**
         * Free the logging implementation.
         * @note This method is THREADSAFE. 
         */
        static void cleanup();

        /**
         * Return the default logger. 
         *
         * @return
         *    a pointer to an AgentLog instance.
         */
        static inline AgentLog* log()
        { 
            AgentLog* r = instance;
            if (!r)
                r = init_ts();
            return r; 
        }

        /**
         * Create a new log entry or reuse an existing one.
         *
         * @param name - The name of the logging module
         * @param type
         *    the type of the log entry as bitwise or of log class and level. 
         */
        static void create_log_entry(const char *name, unsigned char type)
        {
            if (!entry)
            {
                entry = log()->create_log_entry(name, type);
                entry->init();
            }
        }

        /**
         * Return the current log entry. If there is none, an ERROR_LOG entry
         * with level 1 will be created.
         *
         * @return
         *    a pointer to a LogEntry instance.
         */
        static LogEntry* log_entry() 
        {
            if (!entry) {
                create_log_entry("main", ERROR_LOG | 1);
            }
            return entry;
        } 

        /**
         * Delete current log entry.
         */
        static void delete_log_entry() 
        {
            if (entry)
                delete entry;
            entry = 0;
        }

        /**
         * Lock the log singleton.
         */
        static void lock()
        {
#ifdef _THREADS
                mutex.lock();
#endif
        }

        /**
         * Unlock the log singleton.
         */
        static void unlock()
        {
#ifdef _THREADS
                mutex.unlock();
#endif
        }

protected:

        static AgentLog* instance;
        static LogEntry* entry;
#ifdef _THREADS
        static SnmpSynchronized mutex;
#endif
        static const char defaultName;
};

#ifdef SNMP_PP_NAMESPACE
}
#endif

#endif // _SNMP_LOG_H_