/* $Id: messages.c 5496 2002-06-07 13:59:06Z alexk $
**
**  Message and error reporting (possibly fatal).
**
**  Usage:
**
**      extern int cleanup(void);
**      extern void log(int, const char *, va_list, int);
**
**      message_fatal_cleanup = cleanup;
**      message_program_name = argv[0];
**
**      warn("Something horrible happened at %lu", time);
**      syswarn("Couldn't unlink temporary file %s", tmpfile);
**
**      die("Something fatal happened at %lu", time);
**      sysdie("open of %s failed", filename);
**
**      debug("Some debugging message about %s", string);
**      trace(TRACE_PROGRAM, "Program trace output");
**      notice("Informational notices");
**
**      message_handlers_warn(1, log);
**      warn("This now goes through our log function");
**
**  These functions implement message reporting through user-configurable
**  handler functions.  debug() only does something if DEBUG is defined,
**  trace() supports sending trace messages in one of a number of configurable
**  classes of traces so that they can be turned on or off independently, and
**  notice() and warn() just output messages as configured.  die() similarly
**  outputs a message but then exits, normally with a status of 1.
**
**  The sys* versions do the same, but append a colon, a space, and the
**  results of strerror(errno) to the end of the message.  All functions
**  accept printf-style formatting strings and arguments.
**
**  If message_fatal_cleanup is non-NULL, it is called before exit by die and
**  sysdie and its return value is used as the argument to exit.  It is a
**  pointer to a function taking no arguments and returning an int, and can be
**  used to call cleanup functions or to exit in some alternate fashion (such
**  as by calling _exit).
**
**  If message_program_name is non-NULL, the string it points to, followed by
**  a colon and a space, is prepended to all error messages logged through the
**  message_log_stdout and message_log_stderr message handlers (the former is
**  the default for notice, and the latter is the default for warn and die).
**
**  Honoring error_program_name and printing to stderr is just the default
**  handler; with message_handlers_* the handlers for any message function can
**  be changed.  By default, notice prints to stdout, warn and die print to
**  stderr, and the others don't do anything at all.  These functions take a
**  count of handlers and then that many function pointers, each one to a
**  function that takes a message length (the number of characters snprintf
**  generates given the format and arguments), a format, an argument list as a
**  va_list, and the applicable errno value (if any).
*/

/* Used for unused parameters to silence gcc warnings. */
#define UNUSED  __attribute__((__unused__))

/* Make available the bool type. */
#if INN_HAVE_STDBOOL_H
# include <stdbool.h>
#else
# undef true
# undef false
# define true   (1)
# define false  (0)
# ifndef __cplusplus
#  define bool int
# endif
#endif /* INN_HAVE_STDBOOL_H */

#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <errno.h>
#include <syslog.h>
#include <crypt.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>

/* The functions are actually macros so that we can pick up the file and line
   number information for debugging error messages without the user having to
   pass those in every time. */
#define xcalloc(n, size)        x_calloc((n), (size), __FILE__, __LINE__)
#define xmalloc(size)           x_malloc((size), __FILE__, __LINE__)
#define xrealloc(p, size)       x_realloc((p), (size), __FILE__, __LINE__)
#define xstrdup(p)              x_strdup((p), __FILE__, __LINE__)
#define xstrndup(p, size)       x_strndup((p), (size), __FILE__, __LINE__)

/* 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;

/* The default handler lists. */
static message_handler_func stdout_handlers[2] = {
    message_log_stdout, NULL
};
static message_handler_func stderr_handlers[2] = {
    message_log_stderr, NULL
};

/* The list of logging functions currently in effect. */
static message_handler_func *debug_handlers  = NULL;
static message_handler_func *trace_handlers  = NULL;
static message_handler_func *notice_handlers = stdout_handlers;
static message_handler_func *warn_handlers   = stderr_handlers;
static message_handler_func *die_handlers    = stderr_handlers;

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

/* If non-NULL, prepended (followed by ": ") to messages. */
const char *message_program_name = NULL;

/* Whether or not we're currently outputting a particular type of trace. */
static bool tracing[TRACE_ALL] = { false /* false, ... */ };


/*
**  Set the handlers for a particular message function.  Takes a pointer to
**  the handler list, the count of handlers, and the argument list.
*/
static void
message_handlers(message_handler_func **list, int count, va_list args)
{
    int i;

    if (*list != stdout_handlers && *list != stderr_handlers)
        free(*list);
    *list = xmalloc(sizeof(message_handler_func) * (count + 1));
    for (i = 0; i < count; i++)
        (*list)[i] = (message_handler_func) va_arg(args, message_handler_func);
    (*list)[count] = NULL;
}


/*
**  There's no good way of writing these handlers without a bunch of code
**  duplication since we can't assume variadic macros, but I can at least make
**  it easier to write and keep them consistent.
*/
#define HANDLER_FUNCTION(type)                                  \
    void                                                        \
    message_handlers_ ## type(int count, ...)                   \
    {                                                           \
        va_list args;                                           \
                                                                \
        va_start(args, count);                                  \
        message_handlers(& type ## _handlers, count, args);     \
        va_end(args);                                           \
    }
HANDLER_FUNCTION(debug)
HANDLER_FUNCTION(trace)
HANDLER_FUNCTION(notice)
HANDLER_FUNCTION(warn)
HANDLER_FUNCTION(die)


/*
**  Print a message to stdout, supporting message_program_name.
*/
void
message_log_stdout(int len UNUSED, const char *fmt, va_list args, int err)
{
    if (message_program_name != NULL)
        fprintf(stdout, "%s: ", message_program_name);
    vfprintf(stdout, fmt, args);
    if (err)
        fprintf(stdout, ": %s", strerror(err));
    fprintf(stdout, "\n");
}


/*
**  Print a message to stderr, supporting message_program_name.  Also flush
**  stdout so that errors and regular output occur in the right order.
*/
void
message_log_stderr(int len UNUSED, const char *fmt, va_list args, int err)
{
    fflush(stdout);
    if (message_program_name != NULL)
        fprintf(stderr, "%s: ", message_program_name);
    vfprintf(stderr, fmt, args);
    if (err)
        fprintf(stderr, ": %s", strerror(err));
    fprintf(stderr, "\n");
}


/*
**  Log a message to syslog.  This is a helper function used to implement all
**  of the syslog message log handlers.  It takes the same arguments as a
**  regular message handler function but with an additional priority
**  argument.
*/
static void
message_log_syslog(int pri, int len, const char *fmt, va_list args, int err)
{
    char *buffer;

    buffer = malloc(len + 1);
    if (buffer == NULL) {
        fprintf(stderr, "failed to malloc %u bytes at %s line %d: %s",
                len + 1, __FILE__, __LINE__, strerror(errno));
        exit(message_fatal_cleanup ? (*message_fatal_cleanup)() : 1);
    }
    vsnprintf(buffer, len + 1, fmt, args);
    syslog(pri, err ? "%s: %m" : "%s", buffer);
    free(buffer);
}


/*
**  Do the same sort of wrapper to generate all of the separate syslog logging
**  functions.
*/
#define SYSLOG_FUNCTION(name, type)                                     \
    void                                                                \
    message_log_syslog_ ## name(int l, const char *f, va_list a, int e) \
    {                                                                   \
        message_log_syslog(LOG_ ## type, l, f, a, e);                   \
    }
SYSLOG_FUNCTION(debug,   DEBUG)
SYSLOG_FUNCTION(info,    INFO)
SYSLOG_FUNCTION(notice,  NOTICE)
SYSLOG_FUNCTION(warning, WARNING)
SYSLOG_FUNCTION(err,     ERR)
SYSLOG_FUNCTION(crit,    CRIT)


/*
**  Enable or disable tracing for particular classes of messages.
*/
void
message_trace_enable(enum message_trace type, bool enable)
{
    if (type > TRACE_ALL)
        return;
    if (type == TRACE_ALL) {
        int i;

        for (i = 0; i < TRACE_ALL; i++)
            tracing[i] = enable;
    } else {
        tracing[type] = enable;
    }
}


/*
**  All of the message handlers.  There's a lot of code duplication here too,
**  but each one is still *slightly* different and va_start has to be called
**  multiple times, so it's hard to get rid of the duplication.
*/

#ifdef DEBUG
void
debug(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;

    if (debug_handlers == NULL)
        return;
    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length < 0)
        return;
    for (log = debug_handlers; *log != NULL; log++) {
        va_start(args, format);
        (**log)(length, format, args, 0);
        va_end(args);
    }
}
#elif !INN_HAVE_C99_VAMACROS && !INN_HAVE_GNU_VAMACROS
void debug(const char *format UNUSED, ...) { }
#endif

void
trace(enum message_trace type, const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;

    if (trace_handlers == NULL || !tracing[type])
        return;
    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length < 0)
        return;
    for (log = trace_handlers; *log != NULL; log++) {
        va_start(args, format);
        (**log)(length, format, args, 0);
        va_end(args);
    }
}

void
notice(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;

    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length < 0)
        return;
    for (log = notice_handlers; *log != NULL; log++) {
        va_start(args, format);
        (**log)(length, format, args, 0);
        va_end(args);
    }
}

void
sysnotice(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;
    int error = errno;

    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length < 0)
        return;
    for (log = notice_handlers; *log != NULL; log++) {
        va_start(args, format);
        (**log)(length, format, args, error);
        va_end(args);
    }
}

void
warn(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;

    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length < 0)
        return;
    for (log = warn_handlers; *log != NULL; log++) {
        va_start(args, format);
        (**log)(length, format, args, 0);
        va_end(args);
    }
}

void
syswarn(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;
    int error = errno;

    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length < 0)
        return;
    for (log = warn_handlers; *log != NULL; log++) {
        va_start(args, format);
        (**log)(length, format, args, error);
        va_end(args);
    }
}

void
die(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;

    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length >= 0)
        for (log = die_handlers; *log != NULL; log++) {
            va_start(args, format);
            (**log)(length, format, args, 0);
            va_end(args);
        }
    exit(message_fatal_cleanup ? (*message_fatal_cleanup)() : 1);
}

void
sysdie(const char *format, ...)
{
    va_list args;
    message_handler_func *log;
    int length;
    int error = errno;

    va_start(args, format);
    length = vsnprintf(NULL, 0, format, args);
    va_end(args);
    if (length >= 0)
        for (log = die_handlers; *log != NULL; log++) {
            va_start(args, format);
            (**log)(length, format, args, error);
            va_end(args);
        }
    exit(message_fatal_cleanup ? (*message_fatal_cleanup)() : 1);
}