[platform/upstream/glib.git] / glib / gmessages.c

/* GLIB - Library of useful routines for C programming
 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GLib Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GLib at ftp://ftp.gtk.org/pub/gtk/.
 */

/*
 * MT safe
 */

/**
 * SECTION:warnings
 * @Title: Message Output and Debugging Functions
 * @Short_description: functions to output messages and help debug applications
 *
 * These functions provide support for outputting messages.
 *
 * The <function>g_return</function> family of macros (g_return_if_fail(),
 * g_return_val_if_fail(), g_return_if_reached(), g_return_val_if_reached())
 * should only be used for programming errors, a typical use case is
 * checking for invalid parameters at the beginning of a public function.
 * They should not be used if you just mean "if (error) return", they
 * should only be used if you mean "if (bug in program) return".
 * The program behavior is generally considered undefined after one
 * of these checks fails. They are not intended for normal control
 * flow, only to give a perhaps-helpful warning before giving up.
 */

#include "config.h"

#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <signal.h>
#include <locale.h>
#include <errno.h>

#include "gmessages.h"

#include "glib-init.h"
#include "gbacktrace.h"
#include "gcharset.h"
#include "gconvert.h"
#include "gmem.h"
#include "gprintfint.h"
#include "gtestutils.h"
#include "gthread.h"
#include "gstrfuncs.h"
#include "gstring.h"

#ifdef G_OS_WIN32
#include <process.h>            /* For getpid() */
#include <io.h>
#  define _WIN32_WINDOWS 0x0401 /* to get IsDebuggerPresent */
#  include <windows.h>
#endif


/**
 * SECTION:messages
 * @title: Message Logging
 * @short_description: versatile support for logging messages
 *     with different levels of importance
 *
 * These functions provide support for logging error messages
 * or messages used for debugging.
 *
 * There are several built-in levels of messages, defined in
 * #GLogLevelFlags. These can be extended with user-defined levels.
 */

/**
 * G_LOG_DOMAIN:
 *
 * Defines the log domain.
 *
 * For applications, this is typically left as the default %NULL
 * (or "") domain. Libraries should define this so that any messages
 * which they log can be differentiated from messages from other
 * libraries and application code. But be careful not to define
 * it in any public header files.
 *
 * For example, GTK+ uses this in its Makefile.am:
 * |[
 * INCLUDES = -DG_LOG_DOMAIN=\"Gtk\"
 * ]|
 */

/**
 * G_LOG_FATAL_MASK:
 *
 * GLib log levels that are considered fatal by default.
 */

/**
 * GLogFunc:
 * @log_domain: the log domain of the message
 * @log_level: the log level of the message (including the
 *     fatal and recursion flags)
 * @message: the message to process
 * @user_data: user data, set in g_log_set_handler()
 *
 * Specifies the prototype of log handler functions.
 */

/**
 * GLogLevelFlags:
 * @G_LOG_FLAG_RECURSION: internal flag
 * @G_LOG_FLAG_FATAL: internal flag
 * @G_LOG_LEVEL_ERROR: log level for errors, see g_error().
 *     This level is also used for messages produced by g_assert().
 * @G_LOG_LEVEL_CRITICAL: log level for critical messages, see g_critical().
 *     This level is also used for messages produced by g_return_if_fail()
 *     and g_return_val_if_fail().
 * @G_LOG_LEVEL_WARNING: log level for warnings, see g_warning()
 * @G_LOG_LEVEL_MESSAGE: log level for messages, see g_message()
 * @G_LOG_LEVEL_INFO: log level for informational messages
 * @G_LOG_LEVEL_DEBUG: log level for debug messages, see g_debug()
 * @G_LOG_LEVEL_MASK: a mask including all log levels
 *
 * Flags specifying the level of log messages.
 *
 * It is possible to change how GLib treats messages of the various
 * levels using g_log_set_handler() and g_log_set_fatal_mask().
 */

/**
 * g_message:
 * @...: format string, followed by parameters to insert
 *     into the format string (as with printf())
 *
 * A convenience function/macro to log a normal message.
 */

/**
 * g_warning:
 * @...: format string, followed by parameters to insert
 *     into the format string (as with printf())
 *
 * A convenience function/macro to log a warning message.
 *
 * You can make warnings fatal at runtime by setting the
 * %G_DEBUG environment variable (see
 * <ulink url="glib-running.html">Running GLib Applications</ulink>).
 */

/**
 * g_critical:
 * @...: format string, followed by parameters to insert
 *     into the format string (as with printf())
 *
 * Logs a "critical warning" (#G_LOG_LEVEL_CRITICAL).
 * It's more or less application-defined what constitutes
 * a critical vs. a regular warning. You could call
 * g_log_set_always_fatal() to make critical warnings exit
 * the program, then use g_critical() for fatal errors, for
 * example.
 *
 * You can also make critical warnings fatal at runtime by
 * setting the %G_DEBUG environment variable (see
 * <ulink url="glib-running.html">Running GLib Applications</ulink>).
 */

/**
 * g_error:
 * @...: format string, followed by parameters to insert
 *     into the format string (as with printf())
 *
 * A convenience function/macro to log an error message.
 *
 * Error messages are always fatal, resulting in a call to
 * abort() to terminate the application. This function will
 * result in a core dump; don't use it for errors you expect.
 * Using this function indicates a bug in your program, i.e.
 * an assertion failure.
 *
 */

/**
 * g_debug:
 * @...: format string, followed by parameters to insert
 *     into the format string (as with printf())
 *
 * A convenience function/macro to log a debug message.
 *
 * Since: 2.6
 */

/* --- structures --- */
typedef struct _GLogDomain      GLogDomain;
typedef struct _GLogHandler     GLogHandler;
struct _GLogDomain
{
  gchar         *log_domain;
  GLogLevelFlags fatal_mask;
  GLogHandler   *handlers;
  GLogDomain    *next;
};
struct _GLogHandler
{
  guint          id;
  GLogLevelFlags log_level;
  GLogFunc       log_func;
  gpointer       data;
  GLogHandler   *next;
};


/* --- variables --- */
static GMutex         g_messages_lock;
static GLogDomain    *g_log_domains = NULL;
static GPrintFunc     glib_print_func = NULL;
static GPrintFunc     glib_printerr_func = NULL;
static GPrivate       g_log_depth;
static GLogFunc       default_log_func = g_log_default_handler;
static gpointer       default_log_data = NULL;
static GTestLogFatalFunc fatal_log_func = NULL;
static gpointer          fatal_log_data;

/* --- functions --- */
#ifdef G_OS_WIN32
#  include <windows.h>
static gboolean win32_keep_fatal_message = FALSE;

/* This default message will usually be overwritten. */
/* Yes, a fixed size buffer is bad. So sue me. But g_error() is never
 * called with huge strings, is it?
 */
static gchar  fatal_msg_buf[1000] = "Unspecified fatal error encountered, aborting.";
static gchar *fatal_msg_ptr = fatal_msg_buf;

#undef write
static inline int
dowrite (int          fd,
         const void  *buf,
         unsigned int len)
{
  if (win32_keep_fatal_message)
    {
      memcpy (fatal_msg_ptr, buf, len);
      fatal_msg_ptr += len;
      *fatal_msg_ptr = 0;
      return len;
    }

  write (fd, buf, len);

  return len;
}
#define write(fd, buf, len) dowrite(fd, buf, len)

#endif

static void
write_string (int          fd,
              const gchar *string)
{
  write (fd, string, strlen (string));
}

static GLogDomain*
g_log_find_domain_L (const gchar *log_domain)
{
  register GLogDomain *domain;
  
  domain = g_log_domains;
  while (domain)
    {
      if (strcmp (domain->log_domain, log_domain) == 0)
        return domain;
      domain = domain->next;
    }
  return NULL;
}

static GLogDomain*
g_log_domain_new_L (const gchar *log_domain)
{
  register GLogDomain *domain;

  domain = g_new (GLogDomain, 1);
  domain->log_domain = g_strdup (log_domain);
  domain->fatal_mask = G_LOG_FATAL_MASK;
  domain->handlers = NULL;
  
  domain->next = g_log_domains;
  g_log_domains = domain;
  
  return domain;
}

static void
g_log_domain_check_free_L (GLogDomain *domain)
{
  if (domain->fatal_mask == G_LOG_FATAL_MASK &&
      domain->handlers == NULL)
    {
      register GLogDomain *last, *work;
      
      last = NULL;  

      work = g_log_domains;
      while (work)
        {
          if (work == domain)
            {
              if (last)
                last->next = domain->next;
              else
                g_log_domains = domain->next;
              g_free (domain->log_domain);
              g_free (domain);
              break;
            }
          last = work;
          work = last->next;
        }  
    }
}

static GLogFunc
g_log_domain_get_handler_L (GLogDomain  *domain,
                            GLogLevelFlags log_level,
                            gpointer    *data)
{
  if (domain && log_level)
    {
      register GLogHandler *handler;
      
      handler = domain->handlers;
      while (handler)
        {
          if ((handler->log_level & log_level) == log_level)
            {
              *data = handler->data;
              return handler->log_func;
            }
          handler = handler->next;
        }
    }

  *data = default_log_data;
  return default_log_func;
}

/**
 * g_log_set_always_fatal:
 * @fatal_mask: the mask containing bits set for each level
 *     of error which is to be fatal
 *
 * Sets the message levels which are always fatal, in any log domain.
 * When a message with any of these levels is logged the program terminates.
 * You can only set the levels defined by GLib to be fatal.
 * %G_LOG_LEVEL_ERROR is always fatal.
 *
 * You can also make some message levels fatal at runtime by setting
 * the %G_DEBUG environment variable (see
 * <ulink url="glib-running.html">Running GLib Applications</ulink>).
 *
 * Returns: the old fatal mask
 */
GLogLevelFlags
g_log_set_always_fatal (GLogLevelFlags fatal_mask)
{
  GLogLevelFlags old_mask;

  /* restrict the global mask to levels that are known to glib
   * since this setting applies to all domains
   */
  fatal_mask &= (1 << G_LOG_LEVEL_USER_SHIFT) - 1;
  /* force errors to be fatal */
  fatal_mask |= G_LOG_LEVEL_ERROR;
  /* remove bogus flag */
  fatal_mask &= ~G_LOG_FLAG_FATAL;

  g_mutex_lock (&g_messages_lock);
  old_mask = g_log_always_fatal;
  g_log_always_fatal = fatal_mask;
  g_mutex_unlock (&g_messages_lock);

  return old_mask;
}

/**
 * g_log_set_fatal_mask:
 * @log_domain: the log domain
 * @fatal_mask: the new fatal mask
 *
 * Sets the log levels which are fatal in the given domain.
 * %G_LOG_LEVEL_ERROR is always fatal.
 *
 * Returns: the old fatal mask for the log domain
 */
GLogLevelFlags
g_log_set_fatal_mask (const gchar   *log_domain,
                      GLogLevelFlags fatal_mask)
{
  GLogLevelFlags old_flags;
  register GLogDomain *domain;
  
  if (!log_domain)
    log_domain = "";
  
  /* force errors to be fatal */
  fatal_mask |= G_LOG_LEVEL_ERROR;
  /* remove bogus flag */
  fatal_mask &= ~G_LOG_FLAG_FATAL;
  
  g_mutex_lock (&g_messages_lock);

  domain = g_log_find_domain_L (log_domain);
  if (!domain)
    domain = g_log_domain_new_L (log_domain);
  old_flags = domain->fatal_mask;
  
  domain->fatal_mask = fatal_mask;
  g_log_domain_check_free_L (domain);

  g_mutex_unlock (&g_messages_lock);

  return old_flags;
}

/**
 * g_log_set_handler:
 * @log_domain: the log domain, or %NULL for the default ""
 *     application domain
 * @log_levels: the log levels to apply the log handler for.
 *     To handle fatal and recursive messages as well, combine
 *     the log levels with the #G_LOG_FLAG_FATAL and
 *     #G_LOG_FLAG_RECURSION bit flags.
 * @log_func: the log handler function
 * @user_data: data passed to the log handler
 *
 * Sets the log handler for a domain and a set of log levels.
 * To handle fatal and recursive messages the @log_levels parameter
 * must be combined with the #G_LOG_FLAG_FATAL and #G_LOG_FLAG_RECURSION
 * bit flags.
 *
 * Note that since the #G_LOG_LEVEL_ERROR log level is always fatal, if
 * you want to set a handler for this log level you must combine it with
 * #G_LOG_FLAG_FATAL.
 *
 * <example>
 * <title>Adding a log handler for all warning messages in the default
 * (application) domain</title>
 * <programlisting>
 * g_log_set_handler (NULL, G_LOG_LEVEL_WARNING | G_LOG_FLAG_FATAL
 *                    | G_LOG_FLAG_RECURSION, my_log_handler, NULL);
 * </programlisting>
 * </example>
 *
 * <example>
 * <title>Adding a log handler for all critical messages from GTK+</title>
 * <programlisting>
 * g_log_set_handler ("Gtk", G_LOG_LEVEL_CRITICAL | G_LOG_FLAG_FATAL
 *                    | G_LOG_FLAG_RECURSION, my_log_handler, NULL);
 * </programlisting>
 * </example>
 *
 * <example>
 * <title>Adding a log handler for <emphasis>all</emphasis> messages from
 * GLib</title>
 * <programlisting>
 * g_log_set_handler ("GLib", G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL
 *                    | G_LOG_FLAG_RECURSION, my_log_handler, NULL);
 * </programlisting>
 * </example>
 *
 * Returns: the id of the new handler
 */
guint
g_log_set_handler (const gchar   *log_domain,
                   GLogLevelFlags log_levels,
                   GLogFunc       log_func,
                   gpointer       user_data)
{
  static guint handler_id = 0;
  GLogDomain *domain;
  GLogHandler *handler;
  
  g_return_val_if_fail ((log_levels & G_LOG_LEVEL_MASK) != 0, 0);
  g_return_val_if_fail (log_func != NULL, 0);
  
  if (!log_domain)
    log_domain = "";

  handler = g_new (GLogHandler, 1);

  g_mutex_lock (&g_messages_lock);

  domain = g_log_find_domain_L (log_domain);
  if (!domain)
    domain = g_log_domain_new_L (log_domain);
  
  handler->id = ++handler_id;
  handler->log_level = log_levels;
  handler->log_func = log_func;
  handler->data = user_data;
  handler->next = domain->handlers;
  domain->handlers = handler;

  g_mutex_unlock (&g_messages_lock);
  
  return handler_id;
}

/**
 * g_log_set_default_handler:
 * @log_func: the log handler function
 * @user_data: data passed to the log handler
 *
 * Installs a default log handler which is used if no
 * log handler has been set for the particular log domain
 * and log level combination. By default, GLib uses
 * g_log_default_handler() as default log handler.
 *
 * Returns: the previous default log handler
 *
 * Since: 2.6
 */
GLogFunc
g_log_set_default_handler (GLogFunc log_func,
                           gpointer user_data)
{
  GLogFunc old_log_func;
  
  g_mutex_lock (&g_messages_lock);
  old_log_func = default_log_func;
  default_log_func = log_func;
  default_log_data = user_data;
  g_mutex_unlock (&g_messages_lock);
  
  return old_log_func;
}

/**
 * g_test_log_set_fatal_handler:
 * @log_func: the log handler function.
 * @user_data: data passed to the log handler.
 *
 * Installs a non-error fatal log handler which can be
 * used to decide whether log messages which are counted
 * as fatal abort the program.
 *
 * The use case here is that you are running a test case
 * that depends on particular libraries or circumstances
 * and cannot prevent certain known critical or warning
 * messages. So you install a handler that compares the
 * domain and message to precisely not abort in such a case.
 *
 * Note that the handler is reset at the beginning of
 * any test case, so you have to set it inside each test
 * function which needs the special behavior.
 *
 * This handler has no effect on g_error messages.
 *
 * Since: 2.22
 **/
void
g_test_log_set_fatal_handler (GTestLogFatalFunc log_func,
                              gpointer          user_data)
{
  g_mutex_lock (&g_messages_lock);
  fatal_log_func = log_func;
  fatal_log_data = user_data;
  g_mutex_unlock (&g_messages_lock);
}

/**
 * g_log_remove_handler:
 * @log_domain: the log domain
 * @handler_id: the id of the handler, which was returned
 *     in g_log_set_handler()
 *
 * Removes the log handler.
 */
void
g_log_remove_handler (const gchar *log_domain,
                      guint        handler_id)
{
  register GLogDomain *domain;
  
  g_return_if_fail (handler_id > 0);
  
  if (!log_domain)
    log_domain = "";
  
  g_mutex_lock (&g_messages_lock);
  domain = g_log_find_domain_L (log_domain);
  if (domain)
    {
      GLogHandler *work, *last;
      
      last = NULL;
      work = domain->handlers;
      while (work)
        {
          if (work->id == handler_id)
            {
              if (last)
                last->next = work->next;
              else
                domain->handlers = work->next;
              g_log_domain_check_free_L (domain); 
              g_mutex_unlock (&g_messages_lock);
              g_free (work);
              return;
            }
          last = work;
          work = last->next;
        }
    } 
  g_mutex_unlock (&g_messages_lock);
  g_warning ("%s: could not find handler with id `%d' for domain \"%s\"",
             G_STRLOC, handler_id, log_domain);
}

/**
 * g_logv:
 * @log_domain: the log domain
 * @log_level: the log level
 * @format: the message format. See the printf() documentation
 * @args: the parameters to insert into the format string
 *
 * Logs an error or debugging message.
 *
 * If the log level has been set as fatal, the abort()
 * function is called to terminate the program.
 */
void
g_logv (const gchar   *log_domain,
        GLogLevelFlags log_level,
        const gchar   *format,
        va_list        args1)
{
  gboolean was_fatal = (log_level & G_LOG_FLAG_FATAL) != 0;
  gboolean was_recursion = (log_level & G_LOG_FLAG_RECURSION) != 0;
  gint i;

  log_level &= G_LOG_LEVEL_MASK;
  if (!log_level)
    return;

  for (i = g_bit_nth_msf (log_level, -1); i >= 0; i = g_bit_nth_msf (log_level, i))
    {
      register GLogLevelFlags test_level;

      test_level = 1 << i;
      if (log_level & test_level)
        {
          GLogDomain *domain;
          GLogFunc log_func;
          GLogLevelFlags domain_fatal_mask;
          gpointer data = NULL;
          gboolean masquerade_fatal = FALSE;
          guint depth;

          if (was_fatal)
            test_level |= G_LOG_FLAG_FATAL;
          if (was_recursion)
            test_level |= G_LOG_FLAG_RECURSION;

          /* check recursion and lookup handler */
          g_mutex_lock (&g_messages_lock);
          depth = GPOINTER_TO_UINT (g_private_get (&g_log_depth));
          domain = g_log_find_domain_L (log_domain ? log_domain : "");
          if (depth)
            test_level |= G_LOG_FLAG_RECURSION;
          depth++;
          domain_fatal_mask = domain ? domain->fatal_mask : G_LOG_FATAL_MASK;
          if ((domain_fatal_mask | g_log_always_fatal) & test_level)
            test_level |= G_LOG_FLAG_FATAL;
          if (test_level & G_LOG_FLAG_RECURSION)
            log_func = _g_log_fallback_handler;
          else
            log_func = g_log_domain_get_handler_L (domain, test_level, &data);
          domain = NULL;
          g_mutex_unlock (&g_messages_lock);

          g_private_set (&g_log_depth, GUINT_TO_POINTER (depth));


          if (test_level & G_LOG_FLAG_RECURSION)
            {
              /* we use a stack buffer of fixed size, since we're likely
               * in an out-of-memory situation
               */
              gchar buffer[1025];
              gsize size G_GNUC_UNUSED;
              va_list args2;

              G_VA_COPY (args2, args1);
              size = _g_vsnprintf (buffer, 1024, format, args2);
              va_end (args2);

              log_func (log_domain, test_level, buffer, data);
            }
          else
            {
              gchar *msg;
              va_list args2;

              G_VA_COPY (args2, args1);
              msg = g_strdup_vprintf (format, args2);
              va_end (args2);

              log_func (log_domain, test_level, msg, data);

              if ((test_level & G_LOG_FLAG_FATAL)
                && !(test_level & G_LOG_LEVEL_ERROR))
                {
                  masquerade_fatal = fatal_log_func
                    && !fatal_log_func (log_domain, test_level, msg, fatal_log_data);
                }

              g_free (msg);
            }

          if ((test_level & G_LOG_FLAG_FATAL) && !masquerade_fatal)
            {
#ifdef G_OS_WIN32
              gchar *locale_msg = g_locale_from_utf8 (fatal_msg_buf, -1, NULL, NULL, NULL);
              
              MessageBox (NULL, locale_msg, NULL,
                          MB_ICONERROR|MB_SETFOREGROUND);
              if (IsDebuggerPresent () && !(test_level & G_LOG_FLAG_RECURSION))
                G_BREAKPOINT ();
              else
                abort ();
#else
              if (!(test_level & G_LOG_FLAG_RECURSION))
                G_BREAKPOINT ();
              else
                abort ();
#endif /* !G_OS_WIN32 */
            }
          
          depth--;
          g_private_set (&g_log_depth, GUINT_TO_POINTER (depth));
        }
    }
}

/**
 * g_log:
 * @log_domain: the log domain, usually #G_LOG_DOMAIN
 * @log_level: the log level, either from #GLogLevelFlags
 *     or a user-defined level
 * @format: the message format. See the printf() documentation
 * @...: the parameters to insert into the format string
 *
 * Logs an error or debugging message.
 *
 * If the log level has been set as fatal, the abort()
 * function is called to terminate the program.
 */
void
g_log (const gchar   *log_domain,
       GLogLevelFlags log_level,
       const gchar   *format,
       ...)
{
  va_list args;
  
  va_start (args, format);
  g_logv (log_domain, log_level, format, args);
  va_end (args);
}

void
g_return_if_fail_warning (const char *log_domain,
                          const char *pretty_function,
                          const char *expression)
{
  g_log (log_domain,
         G_LOG_LEVEL_CRITICAL,
         "%s: assertion `%s' failed",
         pretty_function,
         expression);
}

void
g_warn_message (const char     *domain,
                const char     *file,
                int             line,
                const char     *func,
                const char     *warnexpr)
{
  char *s, lstr[32];
  g_snprintf (lstr, 32, "%d", line);
  if (warnexpr)
    s = g_strconcat ("(", file, ":", lstr, "):",
                     func, func[0] ? ":" : "",
                     " runtime check failed: (", warnexpr, ")", NULL);
  else
    s = g_strconcat ("(", file, ":", lstr, "):",
                     func, func[0] ? ":" : "",
                     " ", "code should not be reached", NULL);
  g_log (domain, G_LOG_LEVEL_WARNING, "%s", s);
  g_free (s);
}

void
g_assert_warning (const char *log_domain,
                  const char *file,
                  const int   line,
                  const char *pretty_function,
                  const char *expression)
{
  g_log (log_domain,
         G_LOG_LEVEL_ERROR,
         expression 
         ? "file %s: line %d (%s): assertion failed: (%s)"
         : "file %s: line %d (%s): should not be reached",
         file, 
         line, 
         pretty_function,
         expression);
  abort ();
}

#define CHAR_IS_SAFE(wc) (!((wc < 0x20 && wc != '\t' && wc != '\n' && wc != '\r') || \
                            (wc == 0x7f) || \
                            (wc >= 0x80 && wc < 0xa0)))
     
static gchar*
strdup_convert (const gchar *string,
                const gchar *charset)
{
  if (!g_utf8_validate (string, -1, NULL))
    {
      GString *gstring = g_string_new ("[Invalid UTF-8] ");
      guchar *p;

      for (p = (guchar *)string; *p; p++)
        {
          if (CHAR_IS_SAFE(*p) &&
              !(*p == '\r' && *(p + 1) != '\n') &&
              *p < 0x80)
            g_string_append_c (gstring, *p);
          else
            g_string_append_printf (gstring, "\\x%02x", (guint)(guchar)*p);
        }
      
      return g_string_free (gstring, FALSE);
    }
  else
    {
      GError *err = NULL;
      
      gchar *result = g_convert_with_fallback (string, -1, charset, "UTF-8", "?", NULL, NULL, &err);
      if (result)
        return result;
      else
        {
          /* Not thread-safe, but doesn't matter if we print the warning twice
           */
          static gboolean warned = FALSE; 
          if (!warned)
            {
              warned = TRUE;
              _g_fprintf (stderr, "GLib: Cannot convert message: %s\n", err->message);
            }
          g_error_free (err);
          
          return g_strdup (string);
        }
    }
}

/* For a radix of 8 we need at most 3 output bytes for 1 input
 * byte. Additionally we might need up to 2 output bytes for the
 * readix prefix and 1 byte for the trailing NULL.
 */
#define FORMAT_UNSIGNED_BUFSIZE ((GLIB_SIZEOF_LONG * 3) + 3)

static void
format_unsigned (gchar  *buf,
                 gulong  num,
                 guint   radix)
{
  gulong tmp;
  gchar c;
  gint i, n;

  /* we may not call _any_ GLib functions here (or macros like g_return_if_fail()) */

  if (radix != 8 && radix != 10 && radix != 16)
    {
      *buf = '\000';
      return;
    }
  
  if (!num)
    {
      *buf++ = '0';
      *buf = '\000';
      return;
    } 
  
  if (radix == 16)
    {
      *buf++ = '0';
      *buf++ = 'x';
    }
  else if (radix == 8)
    {
      *buf++ = '0';
    }
        
  n = 0;
  tmp = num;
  while (tmp)
    {
      tmp /= radix;
      n++;
    }

  i = n;

  /* Again we can't use g_assert; actually this check should _never_ fail. */
  if (n > FORMAT_UNSIGNED_BUFSIZE - 3)
    {
      *buf = '\000';
      return;
    }

  while (num)
    {
      i--;
      c = (num % radix);
      if (c < 10)
        buf[i] = c + '0';
      else
        buf[i] = c + 'a' - 10;
      num /= radix;
    }
  
  buf[n] = '\000';
}

/* string size big enough to hold level prefix */
#define STRING_BUFFER_SIZE      (FORMAT_UNSIGNED_BUFSIZE + 32)

#define ALERT_LEVELS            (G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL | G_LOG_LEVEL_WARNING)

static int
mklevel_prefix (gchar          level_prefix[STRING_BUFFER_SIZE],
                GLogLevelFlags log_level)
{
  gboolean to_stdout = TRUE;

  /* we may not call _any_ GLib functions here */

  switch (log_level & G_LOG_LEVEL_MASK)
    {
    case G_LOG_LEVEL_ERROR:
      strcpy (level_prefix, "ERROR");
      to_stdout = FALSE;
      break;
    case G_LOG_LEVEL_CRITICAL:
      strcpy (level_prefix, "CRITICAL");
      to_stdout = FALSE;
      break;
    case G_LOG_LEVEL_WARNING:
      strcpy (level_prefix, "WARNING");
      to_stdout = FALSE;
      break;
    case G_LOG_LEVEL_MESSAGE:
      strcpy (level_prefix, "Message");
      to_stdout = FALSE;
      break;
    case G_LOG_LEVEL_INFO:
      strcpy (level_prefix, "INFO");
      break;
    case G_LOG_LEVEL_DEBUG:
      strcpy (level_prefix, "DEBUG");
      break;
    default:
      if (log_level)
        {
          strcpy (level_prefix, "LOG-");
          format_unsigned (level_prefix + 4, log_level & G_LOG_LEVEL_MASK, 16);
        }
      else
        strcpy (level_prefix, "LOG");
      break;
    }
  if (log_level & G_LOG_FLAG_RECURSION)
    strcat (level_prefix, " (recursed)");
  if (log_level & ALERT_LEVELS)
    strcat (level_prefix, " **");

#ifdef G_OS_WIN32
  win32_keep_fatal_message = (log_level & G_LOG_FLAG_FATAL) != 0;
#endif
  return to_stdout ? 1 : 2;
}

void
_g_log_fallback_handler (const gchar   *log_domain,
                         GLogLevelFlags log_level,
                         const gchar   *message,
                         gpointer       unused_data)
{
  gchar level_prefix[STRING_BUFFER_SIZE];
#ifndef G_OS_WIN32
  gchar pid_string[FORMAT_UNSIGNED_BUFSIZE];
#endif
  int fd;

  /* we cannot call _any_ GLib functions in this fallback handler,
   * which is why we skip UTF-8 conversion, etc.
   * since we either recursed or ran out of memory, we're in a pretty
   * pathologic situation anyways, what we can do is giving the
   * the process ID unconditionally however.
   */

  fd = mklevel_prefix (level_prefix, log_level);
  if (!message)
    message = "(NULL) message";

#ifndef G_OS_WIN32
  format_unsigned (pid_string, getpid (), 10);
#endif

  if (log_domain)
    write_string (fd, "\n");
  else
    write_string (fd, "\n** ");

#ifndef G_OS_WIN32
  write_string (fd, "(process:");
  write_string (fd, pid_string);
  write_string (fd, "): ");
#endif

  if (log_domain)
    {
      write_string (fd, log_domain);
      write_string (fd, "-");
    }
  write_string (fd, level_prefix);
  write_string (fd, ": ");
  write_string (fd, message);
}

static void
escape_string (GString *string)
{
  const char *p = string->str;
  gunichar wc;

  while (p < string->str + string->len)
    {
      gboolean safe;
            
      wc = g_utf8_get_char_validated (p, -1);
      if (wc == (gunichar)-1 || wc == (gunichar)-2)  
        {
          gchar *tmp;
          guint pos;

          pos = p - string->str;

          /* Emit invalid UTF-8 as hex escapes 
           */
          tmp = g_strdup_printf ("\\x%02x", (guint)(guchar)*p);
          g_string_erase (string, pos, 1);
          g_string_insert (string, pos, tmp);

          p = string->str + (pos + 4); /* Skip over escape sequence */

          g_free (tmp);
          continue;
        }
      if (wc == '\r')
        {
          safe = *(p + 1) == '\n';
        }
      else
        {
          safe = CHAR_IS_SAFE (wc);
        }
      
      if (!safe)
        {
          gchar *tmp;
          guint pos;

          pos = p - string->str;
          
          /* Largest char we escape is 0x0a, so we don't have to worry
           * about 8-digit \Uxxxxyyyy
           */
          tmp = g_strdup_printf ("\\u%04x", wc); 
          g_string_erase (string, pos, g_utf8_next_char (p) - p);
          g_string_insert (string, pos, tmp);
          g_free (tmp);

          p = string->str + (pos + 6); /* Skip over escape sequence */
        }
      else
        p = g_utf8_next_char (p);
    }
}

/**
 * g_log_default_handler:
 * @log_domain: the log domain of the message
 * @log_level: the level of the message
 * @message: the message
 * @unused_data: data passed from g_log() which is unused
 *
 * The default log handler set up by GLib; g_log_set_default_handler()
 * allows to install an alternate default log handler.
 * This is used if no log handler has been set for the particular log
 * domain and log level combination. It outputs the message to stderr
 * or stdout and if the log level is fatal it calls abort().
 *
 * stderr is used for levels %G_LOG_LEVEL_ERROR, %G_LOG_LEVEL_CRITICAL,
 * %G_LOG_LEVEL_WARNING and %G_LOG_LEVEL_MESSAGE. stdout is used for
 * the rest.
 */
void
g_log_default_handler (const gchar   *log_domain,
                       GLogLevelFlags log_level,
                       const gchar   *message,
                       gpointer       unused_data)
{
  gchar level_prefix[STRING_BUFFER_SIZE], *string;
  GString *gstring;
  int fd;

  /* we can be called externally with recursion for whatever reason */
  if (log_level & G_LOG_FLAG_RECURSION)
    {
      _g_log_fallback_handler (log_domain, log_level, message, unused_data);
      return;
    }

  fd = mklevel_prefix (level_prefix, log_level);

  gstring = g_string_new (NULL);
  if (log_level & ALERT_LEVELS)
    g_string_append (gstring, "\n");
  if (!log_domain)
    g_string_append (gstring, "** ");

  if ((g_log_msg_prefix & log_level) == log_level)
    {
      const gchar *prg_name = g_get_prgname ();
      
      if (!prg_name)
        g_string_append_printf (gstring, "(process:%lu): ", (gulong)getpid ());
      else
        g_string_append_printf (gstring, "(%s:%lu): ", prg_name, (gulong)getpid ());
    }

  if (log_domain)
    {
      g_string_append (gstring, log_domain);
      g_string_append_c (gstring, '-');
    }
  g_string_append (gstring, level_prefix);

  g_string_append (gstring, ": ");
  if (!message)
    g_string_append (gstring, "(NULL) message");
  else
    {
      GString *msg;
      const gchar *charset;

      msg = g_string_new (message);
      escape_string (msg);

      if (g_get_charset (&charset))
        g_string_append (gstring, msg->str);    /* charset is UTF-8 already */
      else
        {
          string = strdup_convert (msg->str, charset);
          g_string_append (gstring, string);
          g_free (string);
        }

      g_string_free (msg, TRUE);
    }
  g_string_append (gstring, "\n");

  string = g_string_free (gstring, FALSE);

  write_string (fd, string);
  g_free (string);
}

/**
 * g_set_print_handler:
 * @func: the new print handler
 *
 * Sets the print handler.
 *
 * Any messages passed to g_print() will be output via
 * the new handler. The default handler simply outputs
 * the message to stdout. By providing your own handler
 * you can redirect the output, to a GTK+ widget or a
 * log file for example.
 *
 * Returns: the old print handler
 */
GPrintFunc
g_set_print_handler (GPrintFunc func)
{
  GPrintFunc old_print_func;

  g_mutex_lock (&g_messages_lock);
  old_print_func = glib_print_func;
  glib_print_func = func;
  g_mutex_unlock (&g_messages_lock);

  return old_print_func;
}

/**
 * g_print:
 * @format: the message format. See the printf() documentation
 * @...: the parameters to insert into the format string
 *
 * Outputs a formatted message via the print handler.
 * The default print handler simply outputs the message to stdout.
 *
 * g_print() should not be used from within libraries for debugging
 * messages, since it may be redirected by applications to special
 * purpose message windows or even files. Instead, libraries should
 * use g_log(), or the convenience functions g_message(), g_warning()
 * and g_error().
 */
void
g_print (const gchar *format,
         ...)
{
  va_list args;
  gchar *string;
  GPrintFunc local_glib_print_func;

  g_return_if_fail (format != NULL);

  va_start (args, format);
  string = g_strdup_vprintf (format, args);
  va_end (args);

  g_mutex_lock (&g_messages_lock);
  local_glib_print_func = glib_print_func;
  g_mutex_unlock (&g_messages_lock);

  if (local_glib_print_func)
    local_glib_print_func (string);
  else
    {
      const gchar *charset;

      if (g_get_charset (&charset))
        fputs (string, stdout); /* charset is UTF-8 already */
      else
        {
          gchar *lstring = strdup_convert (string, charset);

          fputs (lstring, stdout);
          g_free (lstring);
        }
      fflush (stdout);
    }
  g_free (string);
}

/**
 * g_set_printerr_handler:
 * @func: the new error message handler
 *
 * Sets the handler for printing error messages.
 *
 * Any messages passed to g_printerr() will be output via
 * the new handler. The default handler simply outputs the
 * message to stderr. By providing your own handler you can
 * redirect the output, to a GTK+ widget or a log file for
 * example.
 *
 * Returns: the old error message handler
 */
GPrintFunc
g_set_printerr_handler (GPrintFunc func)
{
  GPrintFunc old_printerr_func;

  g_mutex_lock (&g_messages_lock);
  old_printerr_func = glib_printerr_func;
  glib_printerr_func = func;
  g_mutex_unlock (&g_messages_lock);

  return old_printerr_func;
}

/**
 * g_printerr:
 * @format: the message format. See the printf() documentation
 * @...: the parameters to insert into the format string
 *
 * Outputs a formatted message via the error message handler.
 * The default handler simply outputs the message to stderr.
 *
 * g_printerr() should not be used from within libraries.
 * Instead g_log() should be used, or the convenience functions
 * g_message(), g_warning() and g_error().
 */
void
g_printerr (const gchar *format,
            ...)
{
  va_list args;
  gchar *string;
  GPrintFunc local_glib_printerr_func;

  g_return_if_fail (format != NULL);

  va_start (args, format);
  string = g_strdup_vprintf (format, args);
  va_end (args);

  g_mutex_lock (&g_messages_lock);
  local_glib_printerr_func = glib_printerr_func;
  g_mutex_unlock (&g_messages_lock);

  if (local_glib_printerr_func)
    local_glib_printerr_func (string);
  else
    {
      const gchar *charset;

      if (g_get_charset (&charset))
        fputs (string, stderr); /* charset is UTF-8 already */
      else
        {
          gchar *lstring = strdup_convert (string, charset);

          fputs (lstring, stderr);
          g_free (lstring);
        }
      fflush (stderr);
    }
  g_free (string);
}

/**
 * g_printf_string_upper_bound:
 * @format: the format string. See the printf() documentation
 * @args: the parameters to be inserted into the format string
 *
 * Calculates the maximum space needed to store the output
 * of the sprintf() function.
 *
 * Returns: the maximum space needed to store the formatted string
 */
gsize
g_printf_string_upper_bound (const gchar *format,
                             va_list      args)
{
  gchar c;
  return _g_vsnprintf (&c, 1, format, args) + 1;
}