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