glib/gmessages.h

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-or-later
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 /*
  21  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  22  * file for a list of people on the GLib Team.  See the ChangeLog
  23  * files for a list of changes.  These files are distributed with
  24  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  25  */
  26
  27 #ifndef __G_MESSAGES_H__
  28 #define __G_MESSAGES_H__
  29
  30 #if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
  31 #error "Only <glib.h> can be included directly."
  32 #endif
  33
  34 #include <stdarg.h>
  35 #include <glib/gatomic.h>
  36 #include <glib/gtypes.h>
  37 #include <glib/gmacros.h>
  38 #include <glib/gvariant.h>
  39
  40 G_BEGIN_DECLS
  41
  42 /* calculate a string size, guaranteed to fit format + args.
  43  */
  44 GLIB_AVAILABLE_IN_ALL
  45 gsize   g_printf_string_upper_bound (const gchar* format,
  46                                      va_list      args) G_GNUC_PRINTF(1, 0);
  47
  48 /* Log level shift offset for user defined
  49  * log levels (0-7 are used by GLib).
  50  */
  51 #define G_LOG_LEVEL_USER_SHIFT  (8)
  52
  53 /* Glib log levels and flags.
  54  */
  55 typedef enum
  56 {
  57   /* log flags */
  58   G_LOG_FLAG_RECURSION          = 1 << 0,
  59   G_LOG_FLAG_FATAL              = 1 << 1,
  60
  61   /* GLib log levels */
  62   G_LOG_LEVEL_ERROR             = 1 << 2,       /* always fatal */
  63   G_LOG_LEVEL_CRITICAL          = 1 << 3,
  64   G_LOG_LEVEL_WARNING           = 1 << 4,
  65   G_LOG_LEVEL_MESSAGE           = 1 << 5,
  66   G_LOG_LEVEL_INFO              = 1 << 6,
  67   G_LOG_LEVEL_DEBUG             = 1 << 7,
  68
  69   G_LOG_LEVEL_MASK              = ~(G_LOG_FLAG_RECURSION | G_LOG_FLAG_FATAL)
  70 } GLogLevelFlags;
  71
  72 /* GLib log levels that are considered fatal by default */
  73 #define G_LOG_FATAL_MASK        (G_LOG_FLAG_RECURSION | G_LOG_LEVEL_ERROR)
  74
  75 typedef void            (*GLogFunc)             (const gchar   *log_domain,
  76                                                  GLogLevelFlags log_level,
  77                                                  const gchar   *message,
  78                                                  gpointer       user_data);
  79
  80 /* Logging mechanism
  81  */
  82 GLIB_AVAILABLE_IN_ALL
  83 guint           g_log_set_handler       (const gchar    *log_domain,
  84                                          GLogLevelFlags  log_levels,
  85                                          GLogFunc        log_func,
  86                                          gpointer        user_data);
  87 GLIB_AVAILABLE_IN_2_46
  88 guint           g_log_set_handler_full  (const gchar    *log_domain,
  89                                          GLogLevelFlags  log_levels,
  90                                          GLogFunc        log_func,
  91                                          gpointer        user_data,
  92                                          GDestroyNotify  destroy);
  93 GLIB_AVAILABLE_IN_ALL
  94 void            g_log_remove_handler    (const gchar    *log_domain,
  95                                          guint           handler_id);
  96 GLIB_AVAILABLE_IN_ALL
  97 void            g_log_default_handler   (const gchar    *log_domain,
  98                                          GLogLevelFlags  log_level,
  99                                          const gchar    *message,
 100                                          gpointer        unused_data);
 101 GLIB_AVAILABLE_IN_ALL
 102 GLogFunc        g_log_set_default_handler (GLogFunc      log_func,
 103                                            gpointer      user_data);
 104 GLIB_AVAILABLE_IN_ALL
 105 void            g_log                   (const gchar    *log_domain,
 106                                          GLogLevelFlags  log_level,
 107                                          const gchar    *format,
 108                                          ...) G_GNUC_PRINTF (3, 4);
 109 GLIB_AVAILABLE_IN_ALL
 110 void            g_logv                  (const gchar    *log_domain,
 111                                          GLogLevelFlags  log_level,
 112                                          const gchar    *format,
 113                                          va_list         args) G_GNUC_PRINTF(3, 0);
 114 GLIB_AVAILABLE_IN_ALL
 115 GLogLevelFlags  g_log_set_fatal_mask    (const gchar    *log_domain,
 116                                          GLogLevelFlags  fatal_mask);
 117 GLIB_AVAILABLE_IN_ALL
 118 GLogLevelFlags  g_log_set_always_fatal  (GLogLevelFlags  fatal_mask);
 119
 120 /* Structured logging mechanism. */
 121
 122 /**
 123  * GLogWriterOutput:
 124  * @G_LOG_WRITER_HANDLED: Log writer has handled the log entry.
 125  * @G_LOG_WRITER_UNHANDLED: Log writer could not handle the log entry.
 126  *
 127  * Return values from #GLogWriterFuncs to indicate whether the given log entry
 128  * was successfully handled by the writer, or whether there was an error in
 129  * handling it (and hence a fallback writer should be used).
 130  *
 131  * If a #GLogWriterFunc ignores a log entry, it should return
 132  * %G_LOG_WRITER_HANDLED.
 133  *
 134  * Since: 2.50
 135  */
 136 typedef enum
 137 {
 138   G_LOG_WRITER_HANDLED = 1,
 139   G_LOG_WRITER_UNHANDLED = 0,
 140 } GLogWriterOutput;
 141
 142 /**
 143  * GLogField:
 144  * @key: field name (UTF-8 string)
 145  * @value: field value (arbitrary bytes)
 146  * @length: length of @value, in bytes, or -1 if it is nul-terminated
 147  *
 148  * Structure representing a single field in a structured log entry. See
 149  * g_log_structured() for details.
 150  *
 151  * Log fields may contain arbitrary values, including binary with embedded nul
 152  * bytes. If the field contains a string, the string must be UTF-8 encoded and
 153  * have a trailing nul byte. Otherwise, @length must be set to a non-negative
 154  * value.
 155  *
 156  * Since: 2.50
 157  */
 158 typedef struct _GLogField GLogField;
 159 struct _GLogField
 160 {
 161   const gchar *key;
 162   gconstpointer value;
 163   gssize length;
 164 };
 165
 166 /**
 167  * GLogWriterFunc:
 168  * @log_level: log level of the message
 169  * @fields: (array length=n_fields): fields forming the message
 170  * @n_fields: number of @fields
 171  * @user_data: user data passed to g_log_set_writer_func()
 172  *
 173  * Writer function for log entries. A log entry is a collection of one or more
 174  * #GLogFields, using the standard [field names from journal
 175  * specification](https://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html).
 176  * See g_log_structured() for more information.
 177  *
 178  * Writer functions must ignore fields which they do not recognise, unless they
 179  * can write arbitrary binary output, as field values may be arbitrary binary.
 180  *
 181  * @log_level is guaranteed to be included in @fields as the `PRIORITY` field,
 182  * but is provided separately for convenience of deciding whether or where to
 183  * output the log entry.
 184  *
 185  * Writer functions should return %G_LOG_WRITER_HANDLED if they handled the log
 186  * message successfully or if they deliberately ignored it. If there was an
 187  * error handling the message (for example, if the writer function is meant to
 188  * send messages to a remote logging server and there is a network error), it
 189  * should return %G_LOG_WRITER_UNHANDLED. This allows writer functions to be
 190  * chained and fall back to simpler handlers in case of failure.
 191  *
 192  * Returns: %G_LOG_WRITER_HANDLED if the log entry was handled successfully;
 193  *   %G_LOG_WRITER_UNHANDLED otherwise
 194  *
 195  * Since: 2.50
 196  */
 197 typedef GLogWriterOutput (*GLogWriterFunc)     (GLogLevelFlags   log_level,
 198                                                 const GLogField *fields,
 199                                                 gsize            n_fields,
 200                                                 gpointer         user_data);
 201
 202 GLIB_AVAILABLE_IN_2_50
 203 void             g_log_structured              (const gchar     *log_domain,
 204                                                 GLogLevelFlags   log_level,
 205                                                 ...);
 206 GLIB_AVAILABLE_IN_2_50
 207 void             g_log_structured_array        (GLogLevelFlags   log_level,
 208                                                 const GLogField *fields,
 209                                                 gsize            n_fields);
 210
 211 GLIB_AVAILABLE_IN_2_50
 212 void             g_log_variant                 (const gchar     *log_domain,
 213                                                 GLogLevelFlags   log_level,
 214                                                 GVariant        *fields);
 215
 216 GLIB_AVAILABLE_IN_2_50
 217 void             g_log_set_writer_func         (GLogWriterFunc   func,
 218                                                 gpointer         user_data,
 219                                                 GDestroyNotify   user_data_free);
 220
 221 GLIB_AVAILABLE_IN_2_50
 222 gboolean         g_log_writer_supports_color   (gint             output_fd);
 223 GLIB_AVAILABLE_IN_2_50
 224 gboolean         g_log_writer_is_journald      (gint             output_fd);
 225
 226 GLIB_AVAILABLE_IN_2_50
 227 gchar           *g_log_writer_format_fields    (GLogLevelFlags   log_level,
 228                                                 const GLogField *fields,
 229                                                 gsize            n_fields,
 230                                                 gboolean         use_color);
 231
 232 GLIB_AVAILABLE_IN_2_50
 233 GLogWriterOutput g_log_writer_journald         (GLogLevelFlags   log_level,
 234                                                 const GLogField *fields,
 235                                                 gsize            n_fields,
 236                                                 gpointer         user_data);
 237 GLIB_AVAILABLE_IN_2_50
 238 GLogWriterOutput g_log_writer_standard_streams (GLogLevelFlags   log_level,
 239                                                 const GLogField *fields,
 240                                                 gsize            n_fields,
 241                                                 gpointer         user_data);
 242 GLIB_AVAILABLE_IN_2_50
 243 GLogWriterOutput g_log_writer_default          (GLogLevelFlags   log_level,
 244                                                 const GLogField *fields,
 245                                                 gsize            n_fields,
 246                                                 gpointer         user_data);
 247
 248 GLIB_AVAILABLE_IN_2_68
 249 void            g_log_writer_default_set_use_stderr (gboolean use_stderr);
 250 GLIB_AVAILABLE_IN_2_68
 251 gboolean        g_log_writer_default_would_drop (GLogLevelFlags  log_level,
 252                                                  const char     *log_domain);
 253
 254 /* G_MESSAGES_DEBUG enablement */
 255 GLIB_AVAILABLE_IN_2_72
 256 gboolean         g_log_get_debug_enabled       (void);
 257 GLIB_AVAILABLE_IN_2_72
 258 void             g_log_set_debug_enabled       (gboolean         enabled);
 259
 260 /**
 261  * G_DEBUG_HERE:
 262  *
 263  * A convenience form of g_log_structured(), recommended to be added to
 264  * functions when debugging. It prints the current monotonic time and the code
 265  * location using %G_STRLOC.
 266  *
 267  * Since: 2.50
 268  */
 269 #define G_DEBUG_HERE()                                          \
 270   g_log_structured (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG,            \
 271                     "CODE_FILE", __FILE__,                      \
 272                     "CODE_LINE", G_STRINGIFY (__LINE__),        \
 273                     "CODE_FUNC", G_STRFUNC,                      \
 274                     "MESSAGE", "%" G_GINT64_FORMAT ": %s",      \
 275                     g_get_monotonic_time (), G_STRLOC)
 276
 277 /* internal */
 278 void    _g_log_fallback_handler (const gchar   *log_domain,
 279                                                  GLogLevelFlags log_level,
 280                                                  const gchar   *message,
 281                                                  gpointer       unused_data);
 282
 283 /* Internal functions, used to implement the following macros */
 284 GLIB_AVAILABLE_IN_ALL
 285 void g_return_if_fail_warning (const char *log_domain,
 286                                const char *pretty_function,
 287                                const char *expression) G_ANALYZER_NORETURN;
 288 GLIB_AVAILABLE_IN_ALL
 289 void g_warn_message           (const char     *domain,
 290                                const char     *file,
 291                                int             line,
 292                                const char     *func,
 293                                const char     *warnexpr) G_ANALYZER_NORETURN;
 294 GLIB_DEPRECATED
 295 G_NORETURN
 296 void g_assert_warning         (const char *log_domain,
 297                                const char *file,
 298                                const int   line,
 299                                const char *pretty_function,
 300                                const char *expression);
 301
 302 GLIB_AVAILABLE_IN_2_56
 303 void g_log_structured_standard (const gchar    *log_domain,
 304                                 GLogLevelFlags  log_level,
 305                                 const gchar    *file,
 306                                 const gchar    *line,
 307                                 const gchar    *func,
 308                                 const gchar    *message_format,
 309                                 ...) G_GNUC_PRINTF (6, 7);
 310
 311 #ifndef G_LOG_DOMAIN
 312 #define G_LOG_DOMAIN    ((gchar*) 0)
 313 #endif  /* G_LOG_DOMAIN */
 314
 315 #if defined(G_HAVE_ISO_VARARGS) && !G_ANALYZER_ANALYZING
 316 #if defined(G_LOG_USE_STRUCTURED) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_56
 317 #define g_error(...)  G_STMT_START {                                            \
 318                         g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_ERROR, \
 319                                                    __FILE__, G_STRINGIFY (__LINE__), \
 320                                                    G_STRFUNC, __VA_ARGS__); \
 321                         for (;;) ;                                              \
 322                       } G_STMT_END
 323 #define g_message(...)  g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, \
 324                                                    __FILE__, G_STRINGIFY (__LINE__), \
 325                                                    G_STRFUNC, __VA_ARGS__)
 326 #define g_critical(...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL, \
 327                                                    __FILE__, G_STRINGIFY (__LINE__), \
 328                                                    G_STRFUNC, __VA_ARGS__)
 329 #define g_warning(...)  g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, \
 330                                                    __FILE__, G_STRINGIFY (__LINE__), \
 331                                                    G_STRFUNC, __VA_ARGS__)
 332 #define g_info(...)     g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, \
 333                                                    __FILE__, G_STRINGIFY (__LINE__), \
 334                                                    G_STRFUNC, __VA_ARGS__)
 335 #define g_debug(...)    g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, \
 336                                                    __FILE__, G_STRINGIFY (__LINE__), \
 337                                                    G_STRFUNC, __VA_ARGS__)
 338 #else
 339 /* for(;;) ; so that GCC knows that control doesn't go past g_error().
 340  * Put space before ending semicolon to avoid C++ build warnings.
 341  */
 342 #define g_error(...)  G_STMT_START {                 \
 343                         g_log (G_LOG_DOMAIN,         \
 344                                G_LOG_LEVEL_ERROR,    \
 345                                __VA_ARGS__);         \
 346                         for (;;) ;                   \
 347                       } G_STMT_END
 348 #define g_message(...)  g_log (G_LOG_DOMAIN,         \
 349                                G_LOG_LEVEL_MESSAGE,  \
 350                                __VA_ARGS__)
 351 #define g_critical(...) g_log (G_LOG_DOMAIN,         \
 352                                G_LOG_LEVEL_CRITICAL, \
 353                                __VA_ARGS__)
 354 #define g_warning(...)  g_log (G_LOG_DOMAIN,         \
 355                                G_LOG_LEVEL_WARNING,  \
 356                                __VA_ARGS__)
 357 #define g_info(...)     g_log (G_LOG_DOMAIN,         \
 358                                G_LOG_LEVEL_INFO,     \
 359                                __VA_ARGS__)
 360 #define g_debug(...)    g_log (G_LOG_DOMAIN,         \
 361                                G_LOG_LEVEL_DEBUG,    \
 362                                __VA_ARGS__)
 363 #endif
 364 #elif defined(G_HAVE_GNUC_VARARGS)  && !G_ANALYZER_ANALYZING
 365 #if defined(G_LOG_USE_STRUCTURED) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_56
 366 #define g_error(format...)   G_STMT_START {                                          \
 367                                g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_ERROR, \
 368                                                           __FILE__, G_STRINGIFY (__LINE__), \
 369                                                           G_STRFUNC, format); \
 370                                for (;;) ;                                            \
 371                              } G_STMT_END
 372 #define g_message(format...)  g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, \
 373                                                          __FILE__, G_STRINGIFY (__LINE__), \
 374                                                          G_STRFUNC, format)
 375 #define g_critical(format...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL, \
 376                                                          __FILE__, G_STRINGIFY (__LINE__), \
 377                                                          G_STRFUNC, format)
 378 #define g_warning(format...)  g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, \
 379                                                          __FILE__, G_STRINGIFY (__LINE__), \
 380                                                          G_STRFUNC, format)
 381 #define g_info(format...)     g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, \
 382                                                          __FILE__, G_STRINGIFY (__LINE__), \
 383                                                          G_STRFUNC, format)
 384 #define g_debug(format...)    g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, \
 385                                                          __FILE__, G_STRINGIFY (__LINE__), \
 386                                                          G_STRFUNC, format)
 387 #else
 388 #define g_error(format...)    G_STMT_START {                 \
 389                                 g_log (G_LOG_DOMAIN,         \
 390                                        G_LOG_LEVEL_ERROR,    \
 391                                        format);              \
 392                                 for (;;) ;                   \
 393                               } G_STMT_END
 394
 395 #define g_message(format...)    g_log (G_LOG_DOMAIN,         \
 396                                        G_LOG_LEVEL_MESSAGE,  \
 397                                        format)
 398 #define g_critical(format...)   g_log (G_LOG_DOMAIN,         \
 399                                        G_LOG_LEVEL_CRITICAL, \
 400                                        format)
 401 #define g_warning(format...)    g_log (G_LOG_DOMAIN,         \
 402                                        G_LOG_LEVEL_WARNING,  \
 403                                        format)
 404 #define g_info(format...)       g_log (G_LOG_DOMAIN,         \
 405                                        G_LOG_LEVEL_INFO,     \
 406                                        format)
 407 #define g_debug(format...)      g_log (G_LOG_DOMAIN,         \
 408                                        G_LOG_LEVEL_DEBUG,    \
 409                                        format)
 410 #endif
 411 #else   /* no varargs macros */
 412 static G_NORETURN void g_error (const gchar *format, ...) G_ANALYZER_NORETURN;
 413 static void g_critical (const gchar *format, ...) G_ANALYZER_NORETURN;
 414
 415 static inline void
 416 g_error (const gchar *format,
 417          ...)
 418 {
 419   va_list args;
 420   va_start (args, format);
 421   g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_ERROR, format, args);
 422   va_end (args);
 423
 424   for(;;) ;
 425 }
 426 static inline void
 427 g_message (const gchar *format,
 428            ...)
 429 {
 430   va_list args;
 431   va_start (args, format);
 432   g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, format, args);
 433   va_end (args);
 434 }
 435 static inline void
 436 g_critical (const gchar *format,
 437             ...)
 438 {
 439   va_list args;
 440   va_start (args, format);
 441   g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL, format, args);
 442   va_end (args);
 443 }
 444 static inline void
 445 g_warning (const gchar *format,
 446            ...)
 447 {
 448   va_list args;
 449   va_start (args, format);
 450   g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, format, args);
 451   va_end (args);
 452 }
 453 static inline void
 454 g_info (const gchar *format,
 455         ...)
 456 {
 457   va_list args;
 458   va_start (args, format);
 459   g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, format, args);
 460   va_end (args);
 461 }
 462 static inline void
 463 g_debug (const gchar *format,
 464          ...)
 465 {
 466   va_list args;
 467   va_start (args, format);
 468   g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, format, args);
 469   va_end (args);
 470 }
 471 #endif  /* !__GNUC__ */
 472
 473 /**
 474  * g_warning_once:
 475  * @...: format string, followed by parameters to insert
 476  *     into the format string (as with printf())
 477  *
 478  * Logs a warning only once.
 479  *
 480  * g_warning_once() calls g_warning() with the passed message the first time
 481  * the statement is executed; subsequent times it is a no-op.
 482  *
 483  * Note! On platforms where the compiler doesn't support variadic macros, the
 484  * warning is printed each time instead of only once.
 485  *
 486  * Since: 2.64
 487  */
 488 #if defined(G_HAVE_ISO_VARARGS) && !G_ANALYZER_ANALYZING
 489 #define g_warning_once(...) \
 490   G_STMT_START { \
 491     static int G_PASTE (_GWarningOnceBoolean, __LINE__) = 0;  /* (atomic) */ \
 492     if (g_atomic_int_compare_and_exchange (&G_PASTE (_GWarningOnceBoolean, __LINE__), \
 493                                            0, 1)) \
 494       g_warning (__VA_ARGS__); \
 495   } G_STMT_END \
 496   GLIB_AVAILABLE_MACRO_IN_2_64
 497 #elif defined(G_HAVE_GNUC_VARARGS)  && !G_ANALYZER_ANALYZING
 498 #define g_warning_once(format...) \
 499   G_STMT_START { \
 500     static int G_PASTE (_GWarningOnceBoolean, __LINE__) = 0;  /* (atomic) */ \
 501     if (g_atomic_int_compare_and_exchange (&G_PASTE (_GWarningOnceBoolean, __LINE__), \
 502                                            0, 1)) \
 503       g_warning (format); \
 504   } G_STMT_END \
 505   GLIB_AVAILABLE_MACRO_IN_2_64
 506 #else
 507 #define g_warning_once g_warning
 508 #endif
 509
 510 /**
 511  * GPrintFunc:
 512  * @string: the message to output
 513  *
 514  * Specifies the type of the print handler functions.
 515  * These are called with the complete formatted string to output.
 516  */
 517 typedef void    (*GPrintFunc)           (const gchar    *string);
 518 GLIB_AVAILABLE_IN_ALL
 519 void            g_print                 (const gchar    *format,
 520                                          ...) G_GNUC_PRINTF (1, 2);
 521 GLIB_AVAILABLE_IN_ALL
 522 GPrintFunc      g_set_print_handler     (GPrintFunc      func);
 523 GLIB_AVAILABLE_IN_ALL
 524 void            g_printerr              (const gchar    *format,
 525                                          ...) G_GNUC_PRINTF (1, 2);
 526 GLIB_AVAILABLE_IN_ALL
 527 GPrintFunc      g_set_printerr_handler  (GPrintFunc      func);
 528
 529 /**
 530  * g_warn_if_reached:
 531  *
 532  * Logs a warning.
 533  *
 534  * Since: 2.16
 535  */
 536 #define g_warn_if_reached() \
 537   do { \
 538     g_warn_message (G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC, NULL); \
 539   } while (0)
 540
 541 /**
 542  * g_warn_if_fail:
 543  * @expr: the expression to check
 544  *
 545  * Logs a warning if the expression is not true.
 546  *
 547  * Since: 2.16
 548  */
 549 #define g_warn_if_fail(expr) \
 550   do { \
 551     if G_LIKELY (expr) ; \
 552     else g_warn_message (G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC, #expr); \
 553   } while (0)
 554
 555 #ifdef G_DISABLE_CHECKS
 556
 557 /**
 558  * g_return_if_fail:
 559  * @expr: the expression to check
 560  *
 561  * Verifies that the expression @expr, usually representing a precondition,
 562  * evaluates to %TRUE. If the function returns a value, use
 563  * g_return_val_if_fail() instead.
 564  *
 565  * If @expr evaluates to %FALSE, the current function should be considered to
 566  * have undefined behaviour (a programmer error). The only correct solution
 567  * to such an error is to change the module that is calling the current
 568  * function, so that it avoids this incorrect call.
 569  *
 570  * To make this undefined behaviour visible, if @expr evaluates to %FALSE,
 571  * the result is usually that a critical message is logged and the current
 572  * function returns.
 573  *
 574  * If `G_DISABLE_CHECKS` is defined then the check is not performed.  You
 575  * should therefore not depend on any side effects of @expr.
 576  *
 577  * To debug failure of a g_return_if_fail() check, run the code under a debugger
 578  * with `G_DEBUG=fatal-criticals` or `G_DEBUG=fatal-warnings` defined in the
 579  * environment (see [Running GLib Applications](glib-running.html)):
 580  *
 581  * |[
 582  *   G_DEBUG=fatal-warnings gdb ./my-program
 583  * ]|
 584  *
 585  * Any unrelated failures can be skipped over in
 586  * [gdb](https://www.gnu.org/software/gdb/) using the `continue` command.
 587  */
 588 #define g_return_if_fail(expr) G_STMT_START{ (void)0; }G_STMT_END
 589
 590 /**
 591  * g_return_val_if_fail:
 592  * @expr: the expression to check
 593  * @val: the value to return from the current function
 594  *       if the expression is not true
 595  *
 596  * Verifies that the expression @expr, usually representing a precondition,
 597  * evaluates to %TRUE. If the function does not return a value, use
 598  * g_return_if_fail() instead.
 599  *
 600  * If @expr evaluates to %FALSE, the current function should be considered to
 601  * have undefined behaviour (a programmer error). The only correct solution
 602  * to such an error is to change the module that is calling the current
 603  * function, so that it avoids this incorrect call.
 604  *
 605  * To make this undefined behaviour visible, if @expr evaluates to %FALSE,
 606  * the result is usually that a critical message is logged and @val is
 607  * returned from the current function.
 608  *
 609  * If `G_DISABLE_CHECKS` is defined then the check is not performed.  You
 610  * should therefore not depend on any side effects of @expr.
 611  *
 612  * See g_return_if_fail() for guidance on how to debug failure of this check.
 613  */
 614 #define g_return_val_if_fail(expr,val) G_STMT_START{ (void)0; }G_STMT_END
 615
 616 /**
 617  * g_return_if_reached:
 618  *
 619  * Logs a critical message and returns from the current function.
 620  * This can only be used in functions which do not return a value.
 621  *
 622  * See g_return_if_fail() for guidance on how to debug failure of this check.
 623  */
 624 #define g_return_if_reached() G_STMT_START{ return; }G_STMT_END
 625
 626 /**
 627  * g_return_val_if_reached:
 628  * @val: the value to return from the current function
 629  *
 630  * Logs a critical message and returns @val.
 631  *
 632  * See g_return_if_fail() for guidance on how to debug failure of this check.
 633  */
 634 #define g_return_val_if_reached(val) G_STMT_START{ return (val); }G_STMT_END
 635
 636 #else /* !G_DISABLE_CHECKS */
 637
 638 #define g_return_if_fail(expr) \
 639   G_STMT_START { \
 640     if (G_LIKELY (expr)) \
 641       { } \
 642     else \
 643       { \
 644         g_return_if_fail_warning (G_LOG_DOMAIN, \
 645                                   G_STRFUNC, \
 646                                   #expr); \
 647         return; \
 648       } \
 649   } G_STMT_END
 650
 651 #define g_return_val_if_fail(expr, val) \
 652   G_STMT_START { \
 653     if (G_LIKELY (expr)) \
 654       { } \
 655     else \
 656       { \
 657         g_return_if_fail_warning (G_LOG_DOMAIN, \
 658                                   G_STRFUNC, \
 659                                   #expr); \
 660         return (val); \
 661       } \
 662   } G_STMT_END
 663
 664 #define g_return_if_reached() \
 665   G_STMT_START { \
 666     g_log (G_LOG_DOMAIN, \
 667            G_LOG_LEVEL_CRITICAL, \
 668            "file %s: line %d (%s): should not be reached", \
 669            __FILE__, \
 670            __LINE__, \
 671            G_STRFUNC); \
 672     return; \
 673   } G_STMT_END
 674
 675 #define g_return_val_if_reached(val) \
 676   G_STMT_START { \
 677     g_log (G_LOG_DOMAIN, \
 678            G_LOG_LEVEL_CRITICAL, \
 679            "file %s: line %d (%s): should not be reached", \
 680            __FILE__, \
 681            __LINE__, \
 682            G_STRFUNC); \
 683     return (val); \
 684   } G_STMT_END
 685
 686 #endif /* !G_DISABLE_CHECKS */
 687
 688 G_END_DECLS
 689
 690 #endif /* __G_MESSAGES_H__ */