/*  $Id: messages.h,v 1.4 2002/06/07 13:59:06 alexk Exp $
**
**  Logging, debugging, and error reporting functions.
**
**  This collection of functions facilitate logging, debugging, and error
**  reporting in a flexible manner that can be used by libraries as well as by
**  programs.  The functions are based around the idea of handlers, which take
**  a message and do something appropriate with it.  The program can set the
**  appropriate handlers for all the message reporting functions, and then
**  library code can use them with impunity and know the right thing will
**  happen with the messages.
*/

#ifndef INN_MESSAGES_H
#define INN_MESSAGES_H 1

#include <inn/defines.h>
#include <stdarg.h>

BEGIN_DECLS

/* These are the currently-supported types of traces. */
enum message_trace {
    TRACE_NETWORK,              /* Network traffic. */
    TRACE_PROGRAM,              /* Stages of program execution. */
    TRACE_ALL                   /* All traces; this must be last. */
};

/* The reporting functions.  The ones prefaced by "sys" add a colon, a space,
   and the results of strerror(errno) to the output and are intended for
   reporting failures of system calls. */
extern void trace(enum message_trace, const char *, ...)
    __attribute__((__format__(printf, 2, 3)));
extern void notice(const char *, ...)
    __attribute__((__format__(printf, 1, 2)));
extern void sysnotice(const char *, ...)
    __attribute__((__format__(printf, 1, 2)));
extern void warn(const char *, ...)
    __attribute__((__format__(printf, 1, 2)));
extern void syswarn(const char *, ...)
    __attribute__((__format__(printf, 1, 2)));
extern void die(const char *, ...)
    __attribute__((__noreturn__, __format__(printf, 1, 2)));
extern void sysdie(const char *, ...)
    __attribute__((__noreturn__, __format__(printf, 1, 2)));

/* Debug is handled specially, since we want to make the code disappear
   completely unless we're built with -DDEBUG.  We can only do that with
   support for variadic macros, though; otherwise, the function just won't do
   anything. */
#if !defined(DEBUG) && (INN_HAVE_C99_VAMACROS || INN_HAVE_GNU_VAMACROS)
# if INN_HAVE_C99_VAMACROS
#  define debug(format, ...)            /* empty */
# elif INN_HAVE_GNU_VAMACROS
#  define debug(format, args...)        /* empty */
# endif
#else
extern void debug(const char *, ...)
    __attribute__((__format__(printf, 1, 2)));
#endif

/* Set the handlers for various message functions.  All of these functions
   take a count of the number of handlers and then function pointers for each
   of those handlers.  These functions are not thread-safe; they set global
   variables. */
extern void message_handlers_debug(int count, ...);
extern void message_handlers_trace(int count, ...);
extern void message_handlers_notice(int count, ...);
extern void message_handlers_warn(int count, ...);
extern void message_handlers_die(int count, ...);

/* Enable or disable tracing for particular classes of messages. */
extern void message_trace_enable(enum message_trace, bool);

/* Some useful handlers, intended to be passed to message_handlers_*.  All
   handlers take the length of the formatted message, the format, a variadic
   argument list, and the errno setting if any. */
extern void message_log_stdout(int, const char *, va_list, int);
extern void message_log_stderr(int, const char *, va_list, int);
extern void message_log_syslog_debug(int, const char *, va_list, int);
extern void message_log_syslog_info(int, const char *, va_list, int);
extern void message_log_syslog_notice(int, const char *, va_list, int);
extern void message_log_syslog_warning(int, const char *, va_list, int);
extern void message_log_syslog_err(int, const char *, va_list, int);
extern void message_log_syslog_crit(int, const char *, va_list, int);

/* The type of a message handler. */
typedef void (*message_handler_func)(int, const char *, va_list, int);

/* If non-NULL, called before exit and its return value passed to exit. */
extern int (*message_fatal_cleanup)(void);

/* If non-NULL, prepended (followed by ": ") to all messages printed by either
   message_log_stdout or message_log_stderr. */
extern const char *message_program_name;

END_DECLS

#endif /* INN_MESSAGE_H */
