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
38G_BEGIN_DECLS
39
40/* calculate a string size, guaranteed to fit format + args.
41 */
42GLIB_AVAILABLE_IN_ALL
43gsize 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 */
53typedef 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
73typedef void (*GLogFunc) (const gchar *log_domain,
74 GLogLevelFlags log_level,
75 const gchar *message,
76 gpointer user_data);
77
78/* Logging mechanism
79 */
80GLIB_AVAILABLE_IN_ALL
81guint g_log_set_handler (const gchar *log_domain,
82 GLogLevelFlags log_levels,
83 GLogFunc log_func,
84 gpointer user_data);
85GLIB_AVAILABLE_IN_2_46
86guint g_log_set_handler_full (const gchar *log_domain,
87 GLogLevelFlags log_levels,
88 GLogFunc log_func,
89 gpointer user_data,
90 GDestroyNotify destroy);
91GLIB_AVAILABLE_IN_ALL
92void g_log_remove_handler (const gchar *log_domain,
93 guint handler_id);
94GLIB_AVAILABLE_IN_ALL
95void g_log_default_handler (const gchar *log_domain,
96 GLogLevelFlags log_level,
97 const gchar *message,
98 gpointer unused_data);
99GLIB_AVAILABLE_IN_ALL
100GLogFunc g_log_set_default_handler (GLogFunc log_func,
101 gpointer user_data);
102GLIB_AVAILABLE_IN_ALL
103void g_log (const gchar *log_domain,
104 GLogLevelFlags log_level,
105 const gchar *format,
106 ...) G_GNUC_PRINTF (3, 4);
107GLIB_AVAILABLE_IN_ALL
108void g_logv (const gchar *log_domain,
109 GLogLevelFlags log_level,
110 const gchar *format,
111 va_list args) G_GNUC_PRINTF(3, 0);
112GLIB_AVAILABLE_IN_ALL
113GLogLevelFlags g_log_set_fatal_mask (const gchar *log_domain,
114 GLogLevelFlags fatal_mask);
115GLIB_AVAILABLE_IN_ALL
116GLogLevelFlags 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 */
134typedef 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 */
156typedef struct _GLogField GLogField;
157struct _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 * Since: 2.50
193 */
194typedef GLogWriterOutput (*GLogWriterFunc) (GLogLevelFlags log_level,
195 const GLogField *fields,
196 gsize n_fields,
197 gpointer user_data);
198
199GLIB_AVAILABLE_IN_2_50
200void g_log_structured (const gchar *log_domain,
201 GLogLevelFlags log_level,
202 ...);
203GLIB_AVAILABLE_IN_2_50
204void g_log_structured_array (GLogLevelFlags log_level,
205 const GLogField *fields,
206 gsize n_fields);
207
208GLIB_AVAILABLE_IN_2_50
209void g_log_variant (const gchar *log_domain,
210 GLogLevelFlags log_level,
211 GVariant *fields);
212
213GLIB_AVAILABLE_IN_2_50
214void g_log_set_writer_func (GLogWriterFunc func,
215 gpointer user_data,
216 GDestroyNotify user_data_free);
217
218GLIB_AVAILABLE_IN_2_50
219gboolean g_log_writer_supports_color (gint output_fd);
220GLIB_AVAILABLE_IN_2_50
221gboolean g_log_writer_is_journald (gint output_fd);
222
223GLIB_AVAILABLE_IN_2_50
224gchar *g_log_writer_format_fields (GLogLevelFlags log_level,
225 const GLogField *fields,
226 gsize n_fields,
227 gboolean use_color);
228
229GLIB_AVAILABLE_IN_2_50
230GLogWriterOutput g_log_writer_journald (GLogLevelFlags log_level,
231 const GLogField *fields,
232 gsize n_fields,
233 gpointer user_data);
234GLIB_AVAILABLE_IN_2_50
235GLogWriterOutput g_log_writer_standard_streams (GLogLevelFlags log_level,
236 const GLogField *fields,
237 gsize n_fields,
238 gpointer user_data);
239GLIB_AVAILABLE_IN_2_50
240GLogWriterOutput g_log_writer_default (GLogLevelFlags log_level,
241 const GLogField *fields,
242 gsize n_fields,
243 gpointer user_data);
244
245GLIB_AVAILABLE_IN_2_68
246void g_log_writer_default_set_use_stderr (gboolean use_stderr);
247GLIB_AVAILABLE_IN_2_68
248gboolean g_log_writer_default_would_drop (GLogLevelFlags log_level,
249 const char *log_domain);
250
251/**
252 * G_DEBUG_HERE:
253 *
254 * A convenience form of g_log_structured(), recommended to be added to
255 * functions when debugging. It prints the current monotonic time and the code
256 * location using %G_STRLOC.
257 *
258 * Since: 2.50
259 */
260#define G_DEBUG_HERE() \
261 g_log_structured (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, \
262 "CODE_FILE", __FILE__, \
263 "CODE_LINE", G_STRINGIFY (__LINE__), \
264 "CODE_FUNC", G_STRFUNC, \
265 "MESSAGE", "%" G_GINT64_FORMAT ": %s", \
266 g_get_monotonic_time (), G_STRLOC)
267
268/* internal */
269void _g_log_fallback_handler (const gchar *log_domain,
270 GLogLevelFlags log_level,
271 const gchar *message,
272 gpointer unused_data);
273
274/* Internal functions, used to implement the following macros */
275GLIB_AVAILABLE_IN_ALL
276void g_return_if_fail_warning (const char *log_domain,
277 const char *pretty_function,
278 const char *expression) G_ANALYZER_NORETURN;
279GLIB_AVAILABLE_IN_ALL
280void g_warn_message (const char *domain,
281 const char *file,
282 int line,
283 const char *func,
284 const char *warnexpr) G_ANALYZER_NORETURN;
285GLIB_DEPRECATED
286G_NORETURN
287void g_assert_warning (const char *log_domain,
288 const char *file,
289 const int line,
290 const char *pretty_function,
291 const char *expression);
292
293GLIB_AVAILABLE_IN_2_56
294void g_log_structured_standard (const gchar *log_domain,
295 GLogLevelFlags log_level,
296 const gchar *file,
297 const gchar *line,
298 const gchar *func,
299 const gchar *message_format,
300 ...) G_GNUC_PRINTF (6, 7);
301
302#ifndef G_LOG_DOMAIN
303#define G_LOG_DOMAIN ((gchar*) 0)
304#endif /* G_LOG_DOMAIN */
305
306#if defined(G_HAVE_ISO_VARARGS) && !G_ANALYZER_ANALYZING
307#if defined(G_LOG_USE_STRUCTURED) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_56
308#define g_error(...) G_STMT_START { \
309 g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_ERROR, \
310 __FILE__, G_STRINGIFY (__LINE__), \
311 G_STRFUNC, __VA_ARGS__); \
312 for (;;) ; \
313 } G_STMT_END
314#define g_message(...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, \
315 __FILE__, G_STRINGIFY (__LINE__), \
316 G_STRFUNC, __VA_ARGS__)
317#define g_critical(...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL, \
318 __FILE__, G_STRINGIFY (__LINE__), \
319 G_STRFUNC, __VA_ARGS__)
320#define g_warning(...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, \
321 __FILE__, G_STRINGIFY (__LINE__), \
322 G_STRFUNC, __VA_ARGS__)
323#define g_info(...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, \
324 __FILE__, G_STRINGIFY (__LINE__), \
325 G_STRFUNC, __VA_ARGS__)
326#define g_debug(...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, \
327 __FILE__, G_STRINGIFY (__LINE__), \
328 G_STRFUNC, __VA_ARGS__)
329#else
330/* for(;;) ; so that GCC knows that control doesn't go past g_error().
331 * Put space before ending semicolon to avoid C++ build warnings.
332 */
333#define g_error(...) G_STMT_START { \
334 g_log (G_LOG_DOMAIN, \
335 G_LOG_LEVEL_ERROR, \
336 __VA_ARGS__); \
337 for (;;) ; \
338 } G_STMT_END
339#define g_message(...) g_log (G_LOG_DOMAIN, \
340 G_LOG_LEVEL_MESSAGE, \
341 __VA_ARGS__)
342#define g_critical(...) g_log (G_LOG_DOMAIN, \
343 G_LOG_LEVEL_CRITICAL, \
344 __VA_ARGS__)
345#define g_warning(...) g_log (G_LOG_DOMAIN, \
346 G_LOG_LEVEL_WARNING, \
347 __VA_ARGS__)
348#define g_info(...) g_log (G_LOG_DOMAIN, \
349 G_LOG_LEVEL_INFO, \
350 __VA_ARGS__)
351#define g_debug(...) g_log (G_LOG_DOMAIN, \
352 G_LOG_LEVEL_DEBUG, \
353 __VA_ARGS__)
354#endif
355#elif defined(G_HAVE_GNUC_VARARGS) && !G_ANALYZER_ANALYZING
356#if defined(G_LOG_USE_STRUCTURED) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_56
357#define g_error(format...) G_STMT_START { \
358 g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_ERROR, \
359 __FILE__, G_STRINGIFY (__LINE__), \
360 G_STRFUNC, format); \
361 for (;;) ; \
362 } G_STMT_END
363#define g_message(format...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, \
364 __FILE__, G_STRINGIFY (__LINE__), \
365 G_STRFUNC, format)
366#define g_critical(format...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL, \
367 __FILE__, G_STRINGIFY (__LINE__), \
368 G_STRFUNC, format)
369#define g_warning(format...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, \
370 __FILE__, G_STRINGIFY (__LINE__), \
371 G_STRFUNC, format)
372#define g_info(format...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, \
373 __FILE__, G_STRINGIFY (__LINE__), \
374 G_STRFUNC, format)
375#define g_debug(format...) g_log_structured_standard (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, \
376 __FILE__, G_STRINGIFY (__LINE__), \
377 G_STRFUNC, format)
378#else
379#define g_error(format...) G_STMT_START { \
380 g_log (G_LOG_DOMAIN, \
381 G_LOG_LEVEL_ERROR, \
382 format); \
383 for (;;) ; \
384 } G_STMT_END
385
386#define g_message(format...) g_log (G_LOG_DOMAIN, \
387 G_LOG_LEVEL_MESSAGE, \
388 format)
389#define g_critical(format...) g_log (G_LOG_DOMAIN, \
390 G_LOG_LEVEL_CRITICAL, \
391 format)
392#define g_warning(format...) g_log (G_LOG_DOMAIN, \
393 G_LOG_LEVEL_WARNING, \
394 format)
395#define g_info(format...) g_log (G_LOG_DOMAIN, \
396 G_LOG_LEVEL_INFO, \
397 format)
398#define g_debug(format...) g_log (G_LOG_DOMAIN, \
399 G_LOG_LEVEL_DEBUG, \
400 format)
401#endif
402#else /* no varargs macros */
403static G_NORETURN void g_error (const gchar *format, ...) G_ANALYZER_NORETURN;
404static void g_critical (const gchar *format, ...) G_ANALYZER_NORETURN;
405
406static inline void
407g_error (const gchar *format,
408 ...)
409{
410 va_list args;
411 va_start (args, format);
412 g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_ERROR, format, args);
413 va_end (args);
414
415 for(;;) ;
416}
417static inline void
418g_message (const gchar *format,
419 ...)
420{
421 va_list args;
422 va_start (args, format);
423 g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, format, args);
424 va_end (args);
425}
426static inline void
427g_critical (const gchar *format,
428 ...)
429{
430 va_list args;
431 va_start (args, format);
432 g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL, format, args);
433 va_end (args);
434}
435static inline void
436g_warning (const gchar *format,
437 ...)
438{
439 va_list args;
440 va_start (args, format);
441 g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, format, args);
442 va_end (args);
443}
444static inline void
445g_info (const gchar *format,
446 ...)
447{
448 va_list args;
449 va_start (args, format);
450 g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, format, args);
451 va_end (args);
452}
453static inline void
454g_debug (const gchar *format,
455 ...)
456{
457 va_list args;
458 va_start (args, format);
459 g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, format, args);
460 va_end (args);
461}
462#endif /* !__GNUC__ */
463
464/**
465 * g_warning_once:
466 * @...: format string, followed by parameters to insert
467 * into the format string (as with printf())
468 *
469 * Logs a warning only once.
470 *
471 * g_warning_once() calls g_warning() with the passed message the first time
472 * the statement is executed; subsequent times it is a no-op.
473 *
474 * Note! On platforms where the compiler doesn't support variadic macros, the
475 * warning is printed each time instead of only once.
476 *
477 * Since: 2.64
478 */
479#if defined(G_HAVE_ISO_VARARGS) && !G_ANALYZER_ANALYZING
480#define g_warning_once(...) \
481 G_STMT_START { \
482 static int G_PASTE (_GWarningOnceBoolean, __LINE__) = 0; /* (atomic) */ \
483 if (g_atomic_int_compare_and_exchange (&G_PASTE (_GWarningOnceBoolean, __LINE__), \
484 0, 1)) \
485 g_warning (__VA_ARGS__); \
486 } G_STMT_END \
487 GLIB_AVAILABLE_MACRO_IN_2_64
488#elif defined(G_HAVE_GNUC_VARARGS) && !G_ANALYZER_ANALYZING
489#define g_warning_once(format...) \
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 (format); \
495 } G_STMT_END \
496 GLIB_AVAILABLE_MACRO_IN_2_64
497#else
498#define g_warning_once g_warning
499#endif
500
501/**
502 * GPrintFunc:
503 * @string: the message to output
504 *
505 * Specifies the type of the print handler functions.
506 * These are called with the complete formatted string to output.
507 */
508typedef void (*GPrintFunc) (const gchar *string);
509GLIB_AVAILABLE_IN_ALL
510void g_print (const gchar *format,
511 ...) G_GNUC_PRINTF (1, 2);
512GLIB_AVAILABLE_IN_ALL
513GPrintFunc g_set_print_handler (GPrintFunc func);
514GLIB_AVAILABLE_IN_ALL
515void g_printerr (const gchar *format,
516 ...) G_GNUC_PRINTF (1, 2);
517GLIB_AVAILABLE_IN_ALL
518GPrintFunc g_set_printerr_handler (GPrintFunc func);
519
520/**
521 * g_warn_if_reached:
522 *
523 * Logs a warning.
524 *
525 * Since: 2.16
526 */
527#define g_warn_if_reached() \
528 do { \
529 g_warn_message (G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC, NULL); \
530 } while (0)
531
532/**
533 * g_warn_if_fail:
534 * @expr: the expression to check
535 *
536 * Logs a warning if the expression is not true.
537 *
538 * Since: 2.16
539 */
540#define g_warn_if_fail(expr) \
541 do { \
542 if G_LIKELY (expr) ; \
543 else g_warn_message (G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC, #expr); \
544 } while (0)
545
546#ifdef G_DISABLE_CHECKS
547
548/**
549 * g_return_if_fail:
550 * @expr: the expression to check
551 *
552 * Verifies that the expression @expr, usually representing a precondition,
553 * evaluates to %TRUE. If the function returns a value, use
554 * g_return_val_if_fail() instead.
555 *
556 * If @expr evaluates to %FALSE, the current function should be considered to
557 * have undefined behaviour (a programmer error). The only correct solution
558 * to such an error is to change the module that is calling the current
559 * function, so that it avoids this incorrect call.
560 *
561 * To make this undefined behaviour visible, if @expr evaluates to %FALSE,
562 * the result is usually that a critical message is logged and the current
563 * function returns.
564 *
565 * If `G_DISABLE_CHECKS` is defined then the check is not performed. You
566 * should therefore not depend on any side effects of @expr.
567 *
568 * To debug failure of a g_return_if_fail() check, run the code under a debugger
569 * with `G_DEBUG=fatal-criticals` or `G_DEBUG=fatal-warnings` defined in the
570 * environment (see [Running GLib Applications](glib-running.html)):
571 *
572 * |[
573 * G_DEBUG=fatal-warnings gdb ./my-program
574 * ]|
575 *
576 * Any unrelated failures can be skipped over in
577 * [gdb](https://www.gnu.org/software/gdb/) using the `continue` command.
578 */
579#define g_return_if_fail(expr) G_STMT_START{ (void)0; }G_STMT_END
580
581/**
582 * g_return_val_if_fail:
583 * @expr: the expression to check
584 * @val: the value to return from the current function
585 * if the expression is not true
586 *
587 * Verifies that the expression @expr, usually representing a precondition,
588 * evaluates to %TRUE. If the function does not return a value, use
589 * g_return_if_fail() instead.
590 *
591 * If @expr evaluates to %FALSE, the current function should be considered to
592 * have undefined behaviour (a programmer error). The only correct solution
593 * to such an error is to change the module that is calling the current
594 * function, so that it avoids this incorrect call.
595 *
596 * To make this undefined behaviour visible, if @expr evaluates to %FALSE,
597 * the result is usually that a critical message is logged and @val is
598 * returned from the current function.
599 *
600 * If `G_DISABLE_CHECKS` is defined then the check is not performed. You
601 * should therefore not depend on any side effects of @expr.
602 *
603 * See g_return_if_fail() for guidance on how to debug failure of this check.
604 */
605#define g_return_val_if_fail(expr,val) G_STMT_START{ (void)0; }G_STMT_END
606
607/**
608 * g_return_if_reached:
609 *
610 * Logs a critical message and returns from the current function.
611 * This can only be used in functions which do not return a value.
612 *
613 * See g_return_if_fail() for guidance on how to debug failure of this check.
614 */
615#define g_return_if_reached() G_STMT_START{ return; }G_STMT_END
616
617/**
618 * g_return_val_if_reached:
619 * @val: the value to return from the current function
620 *
621 * Logs a critical message and returns @val.
622 *
623 * See g_return_if_fail() for guidance on how to debug failure of this check.
624 */
625#define g_return_val_if_reached(val) G_STMT_START{ return (val); }G_STMT_END
626
627#else /* !G_DISABLE_CHECKS */
628
629#define g_return_if_fail(expr) \
630 G_STMT_START { \
631 if (G_LIKELY (expr)) \
632 { } \
633 else \
634 { \
635 g_return_if_fail_warning (G_LOG_DOMAIN, \
636 G_STRFUNC, \
637 #expr); \
638 return; \
639 } \
640 } G_STMT_END
641
642#define g_return_val_if_fail(expr, val) \
643 G_STMT_START { \
644 if (G_LIKELY (expr)) \
645 { } \
646 else \
647 { \
648 g_return_if_fail_warning (G_LOG_DOMAIN, \
649 G_STRFUNC, \
650 #expr); \
651 return (val); \
652 } \
653 } G_STMT_END
654
655#define g_return_if_reached() \
656 G_STMT_START { \
657 g_log (G_LOG_DOMAIN, \
658 G_LOG_LEVEL_CRITICAL, \
659 "file %s: line %d (%s): should not be reached", \
660 __FILE__, \
661 __LINE__, \
662 G_STRFUNC); \
663 return; \
664 } G_STMT_END
665
666#define g_return_val_if_reached(val) \
667 G_STMT_START { \
668 g_log (G_LOG_DOMAIN, \
669 G_LOG_LEVEL_CRITICAL, \
670 "file %s: line %d (%s): should not be reached", \
671 __FILE__, \
672 __LINE__, \
673 G_STRFUNC); \
674 return (val); \
675 } G_STMT_END
676
677#endif /* !G_DISABLE_CHECKS */
678
679G_END_DECLS
680
681#endif /* __G_MESSAGES_H__ */
682

source code of gtk/subprojects/glib/glib/gmessages.h