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