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 | /** |
26 | * SECTION:error_reporting |
27 | * @Title: Error Reporting |
28 | * @Short_description: a system for reporting errors |
29 | * |
30 | * GLib provides a standard method of reporting errors from a called |
31 | * function to the calling code. (This is the same problem solved by |
32 | * exceptions in other languages.) It's important to understand that |
33 | * this method is both a data type (the #GError struct) and a [set of |
34 | * rules][gerror-rules]. If you use #GError incorrectly, then your code will not |
35 | * properly interoperate with other code that uses #GError, and users |
36 | * of your API will probably get confused. In most cases, [using #GError is |
37 | * preferred over numeric error codes][gerror-comparison], but there are |
38 | * situations where numeric error codes are useful for performance. |
39 | * |
40 | * First and foremost: #GError should only be used to report recoverable |
41 | * runtime errors, never to report programming errors. If the programmer |
42 | * has screwed up, then you should use g_warning(), g_return_if_fail(), |
43 | * g_assert(), g_error(), or some similar facility. (Incidentally, |
44 | * remember that the g_error() function should only be used for |
45 | * programming errors, it should not be used to print any error |
46 | * reportable via #GError.) |
47 | * |
48 | * Examples of recoverable runtime errors are "file not found" or |
49 | * "failed to parse input." Examples of programming errors are "NULL |
50 | * passed to strcmp()" or "attempted to free the same pointer twice." |
51 | * These two kinds of errors are fundamentally different: runtime errors |
52 | * should be handled or reported to the user, programming errors should |
53 | * be eliminated by fixing the bug in the program. This is why most |
54 | * functions in GLib and GTK+ do not use the #GError facility. |
55 | * |
56 | * Functions that can fail take a return location for a #GError as their |
57 | * last argument. On error, a new #GError instance will be allocated and |
58 | * returned to the caller via this argument. For example: |
59 | * |[<!-- language="C" --> |
60 | * gboolean g_file_get_contents (const gchar *filename, |
61 | * gchar **contents, |
62 | * gsize *length, |
63 | * GError **error); |
64 | * ]| |
65 | * If you pass a non-%NULL value for the `error` argument, it should |
66 | * point to a location where an error can be placed. For example: |
67 | * |[<!-- language="C" --> |
68 | * gchar *contents; |
69 | * GError *err = NULL; |
70 | * |
71 | * g_file_get_contents ("foo.txt", &contents, NULL, &err); |
72 | * g_assert ((contents == NULL && err != NULL) || (contents != NULL && err == NULL)); |
73 | * if (err != NULL) |
74 | * { |
75 | * // Report error to user, and free error |
76 | * g_assert (contents == NULL); |
77 | * fprintf (stderr, "Unable to read file: %s\n", err->message); |
78 | * g_error_free (err); |
79 | * } |
80 | * else |
81 | * { |
82 | * // Use file contents |
83 | * g_assert (contents != NULL); |
84 | * } |
85 | * ]| |
86 | * Note that `err != NULL` in this example is a reliable indicator |
87 | * of whether g_file_get_contents() failed. Additionally, |
88 | * g_file_get_contents() returns a boolean which |
89 | * indicates whether it was successful. |
90 | * |
91 | * Because g_file_get_contents() returns %FALSE on failure, if you |
92 | * are only interested in whether it failed and don't need to display |
93 | * an error message, you can pass %NULL for the @error argument: |
94 | * |[<!-- language="C" --> |
95 | * if (g_file_get_contents ("foo.txt", &contents, NULL, NULL)) // ignore errors |
96 | * // no error occurred |
97 | * ; |
98 | * else |
99 | * // error |
100 | * ; |
101 | * ]| |
102 | * |
103 | * The #GError object contains three fields: @domain indicates the module |
104 | * the error-reporting function is located in, @code indicates the specific |
105 | * error that occurred, and @message is a user-readable error message with |
106 | * as many details as possible. Several functions are provided to deal |
107 | * with an error received from a called function: g_error_matches() |
108 | * returns %TRUE if the error matches a given domain and code, |
109 | * g_propagate_error() copies an error into an error location (so the |
110 | * calling function will receive it), and g_clear_error() clears an |
111 | * error location by freeing the error and resetting the location to |
112 | * %NULL. To display an error to the user, simply display the @message, |
113 | * perhaps along with additional context known only to the calling |
114 | * function (the file being opened, or whatever - though in the |
115 | * g_file_get_contents() case, the @message already contains a filename). |
116 | * |
117 | * Note, however, that many error messages are too technical to display to the |
118 | * user in an application, so prefer to use g_error_matches() to categorize errors |
119 | * from called functions, and build an appropriate error message for the context |
120 | * within your application. Error messages from a #GError are more appropriate |
121 | * to be printed in system logs or on the command line. They are typically |
122 | * translated. |
123 | * |
124 | * When implementing a function that can report errors, the basic |
125 | * tool is g_set_error(). Typically, if a fatal error occurs you |
126 | * want to g_set_error(), then return immediately. g_set_error() |
127 | * does nothing if the error location passed to it is %NULL. |
128 | * Here's an example: |
129 | * |[<!-- language="C" --> |
130 | * gint |
131 | * foo_open_file (GError **error) |
132 | * { |
133 | * gint fd; |
134 | * int saved_errno; |
135 | * |
136 | * g_return_val_if_fail (error == NULL || *error == NULL, -1); |
137 | * |
138 | * fd = open ("file.txt", O_RDONLY); |
139 | * saved_errno = errno; |
140 | * |
141 | * if (fd < 0) |
142 | * { |
143 | * g_set_error (error, |
144 | * FOO_ERROR, // error domain |
145 | * FOO_ERROR_BLAH, // error code |
146 | * "Failed to open file: %s", // error message format string |
147 | * g_strerror (saved_errno)); |
148 | * return -1; |
149 | * } |
150 | * else |
151 | * return fd; |
152 | * } |
153 | * ]| |
154 | * |
155 | * Things are somewhat more complicated if you yourself call another |
156 | * function that can report a #GError. If the sub-function indicates |
157 | * fatal errors in some way other than reporting a #GError, such as |
158 | * by returning %TRUE on success, you can simply do the following: |
159 | * |[<!-- language="C" --> |
160 | * gboolean |
161 | * my_function_that_can_fail (GError **err) |
162 | * { |
163 | * g_return_val_if_fail (err == NULL || *err == NULL, FALSE); |
164 | * |
165 | * if (!sub_function_that_can_fail (err)) |
166 | * { |
167 | * // assert that error was set by the sub-function |
168 | * g_assert (err == NULL || *err != NULL); |
169 | * return FALSE; |
170 | * } |
171 | * |
172 | * // otherwise continue, no error occurred |
173 | * g_assert (err == NULL || *err == NULL); |
174 | * } |
175 | * ]| |
176 | * |
177 | * If the sub-function does not indicate errors other than by |
178 | * reporting a #GError (or if its return value does not reliably indicate |
179 | * errors) you need to create a temporary #GError |
180 | * since the passed-in one may be %NULL. g_propagate_error() is |
181 | * intended for use in this case. |
182 | * |[<!-- language="C" --> |
183 | * gboolean |
184 | * my_function_that_can_fail (GError **err) |
185 | * { |
186 | * GError *tmp_error; |
187 | * |
188 | * g_return_val_if_fail (err == NULL || *err == NULL, FALSE); |
189 | * |
190 | * tmp_error = NULL; |
191 | * sub_function_that_can_fail (&tmp_error); |
192 | * |
193 | * if (tmp_error != NULL) |
194 | * { |
195 | * // store tmp_error in err, if err != NULL, |
196 | * // otherwise call g_error_free() on tmp_error |
197 | * g_propagate_error (err, tmp_error); |
198 | * return FALSE; |
199 | * } |
200 | * |
201 | * // otherwise continue, no error occurred |
202 | * } |
203 | * ]| |
204 | * |
205 | * Error pileups are always a bug. For example, this code is incorrect: |
206 | * |[<!-- language="C" --> |
207 | * gboolean |
208 | * my_function_that_can_fail (GError **err) |
209 | * { |
210 | * GError *tmp_error; |
211 | * |
212 | * g_return_val_if_fail (err == NULL || *err == NULL, FALSE); |
213 | * |
214 | * tmp_error = NULL; |
215 | * sub_function_that_can_fail (&tmp_error); |
216 | * other_function_that_can_fail (&tmp_error); |
217 | * |
218 | * if (tmp_error != NULL) |
219 | * { |
220 | * g_propagate_error (err, tmp_error); |
221 | * return FALSE; |
222 | * } |
223 | * } |
224 | * ]| |
225 | * @tmp_error should be checked immediately after sub_function_that_can_fail(), |
226 | * and either cleared or propagated upward. The rule is: after each error, |
227 | * you must either handle the error, or return it to the calling function. |
228 | * |
229 | * Note that passing %NULL for the error location is the equivalent |
230 | * of handling an error by always doing nothing about it. So the |
231 | * following code is fine, assuming errors in sub_function_that_can_fail() |
232 | * are not fatal to my_function_that_can_fail(): |
233 | * |[<!-- language="C" --> |
234 | * gboolean |
235 | * my_function_that_can_fail (GError **err) |
236 | * { |
237 | * GError *tmp_error; |
238 | * |
239 | * g_return_val_if_fail (err == NULL || *err == NULL, FALSE); |
240 | * |
241 | * sub_function_that_can_fail (NULL); // ignore errors |
242 | * |
243 | * tmp_error = NULL; |
244 | * other_function_that_can_fail (&tmp_error); |
245 | * |
246 | * if (tmp_error != NULL) |
247 | * { |
248 | * g_propagate_error (err, tmp_error); |
249 | * return FALSE; |
250 | * } |
251 | * } |
252 | * ]| |
253 | * |
254 | * Note that passing %NULL for the error location ignores errors; |
255 | * it's equivalent to |
256 | * `try { sub_function_that_can_fail (); } catch (...) {}` |
257 | * in C++. It does not mean to leave errors unhandled; it means |
258 | * to handle them by doing nothing. |
259 | * |
260 | * Error domains and codes are conventionally named as follows: |
261 | * |
262 | * - The error domain is called <NAMESPACE>_<MODULE>_ERROR, |
263 | * for example %G_SPAWN_ERROR or %G_THREAD_ERROR: |
264 | * |[<!-- language="C" --> |
265 | * #define G_SPAWN_ERROR g_spawn_error_quark () |
266 | * |
267 | * G_DEFINE_QUARK (g-spawn-error-quark, g_spawn_error) |
268 | * ]| |
269 | * |
270 | * - The quark function for the error domain is called |
271 | * <namespace>_<module>_error_quark, |
272 | * for example g_spawn_error_quark() or g_thread_error_quark(). |
273 | * |
274 | * - The error codes are in an enumeration called |
275 | * <Namespace><Module>Error; |
276 | * for example, #GThreadError or #GSpawnError. |
277 | * |
278 | * - Members of the error code enumeration are called |
279 | * <NAMESPACE>_<MODULE>_ERROR_<CODE>, |
280 | * for example %G_SPAWN_ERROR_FORK or %G_THREAD_ERROR_AGAIN. |
281 | * |
282 | * - If there's a "generic" or "unknown" error code for unrecoverable |
283 | * errors it doesn't make sense to distinguish with specific codes, |
284 | * it should be called <NAMESPACE>_<MODULE>_ERROR_FAILED, |
285 | * for example %G_SPAWN_ERROR_FAILED. In the case of error code |
286 | * enumerations that may be extended in future releases, you should |
287 | * generally not handle this error code explicitly, but should |
288 | * instead treat any unrecognized error code as equivalent to |
289 | * FAILED. |
290 | * |
291 | * ## Comparison of #GError and traditional error handling # {#gerror-comparison} |
292 | * |
293 | * #GError has several advantages over traditional numeric error codes: |
294 | * importantly, tools like |
295 | * [gobject-introspection](https://developer.gnome.org/gi/stable/) understand |
296 | * #GErrors and convert them to exceptions in bindings; the message includes |
297 | * more information than just a code; and use of a domain helps prevent |
298 | * misinterpretation of error codes. |
299 | * |
300 | * #GError has disadvantages though: it requires a memory allocation, and |
301 | * formatting the error message string has a performance overhead. This makes it |
302 | * unsuitable for use in retry loops where errors are a common case, rather than |
303 | * being unusual. For example, using %G_IO_ERROR_WOULD_BLOCK means hitting these |
304 | * overheads in the normal control flow. String formatting overhead can be |
305 | * eliminated by using g_set_error_literal() in some cases. |
306 | * |
307 | * These performance issues can be compounded if a function wraps the #GErrors |
308 | * returned by the functions it calls: this multiplies the number of allocations |
309 | * and string formatting operations. This can be partially mitigated by using |
310 | * g_prefix_error(). |
311 | * |
312 | * ## Rules for use of #GError # {#gerror-rules} |
313 | * |
314 | * Summary of rules for use of #GError: |
315 | * |
316 | * - Do not report programming errors via #GError. |
317 | * |
318 | * - The last argument of a function that returns an error should |
319 | * be a location where a #GError can be placed (i.e. `GError **error`). |
320 | * If #GError is used with varargs, the `GError**` should be the last |
321 | * argument before the `...`. |
322 | * |
323 | * - The caller may pass %NULL for the `GError**` if they are not interested |
324 | * in details of the exact error that occurred. |
325 | * |
326 | * - If %NULL is passed for the `GError**` argument, then errors should |
327 | * not be returned to the caller, but your function should still |
328 | * abort and return if an error occurs. That is, control flow should |
329 | * not be affected by whether the caller wants to get a #GError. |
330 | * |
331 | * - If a #GError is reported, then your function by definition had a |
332 | * fatal failure and did not complete whatever it was supposed to do. |
333 | * If the failure was not fatal, then you handled it and you should not |
334 | * report it. If it was fatal, then you must report it and discontinue |
335 | * whatever you were doing immediately. |
336 | * |
337 | * - If a #GError is reported, out parameters are not guaranteed to |
338 | * be set to any defined value. |
339 | * |
340 | * - A `GError*` must be initialized to %NULL before passing its address |
341 | * to a function that can report errors. |
342 | * |
343 | * - #GError structs must not be stack-allocated. |
344 | * |
345 | * - "Piling up" errors is always a bug. That is, if you assign a |
346 | * new #GError to a `GError*` that is non-%NULL, thus overwriting |
347 | * the previous error, it indicates that you should have aborted |
348 | * the operation instead of continuing. If you were able to continue, |
349 | * you should have cleared the previous error with g_clear_error(). |
350 | * g_set_error() will complain if you pile up errors. |
351 | * |
352 | * - By convention, if you return a boolean value indicating success |
353 | * then %TRUE means success and %FALSE means failure. Avoid creating |
354 | * functions which have a boolean return value and a #GError parameter, |
355 | * but where the boolean does something other than signal whether the |
356 | * #GError is set. Among other problems, it requires C callers to allocate |
357 | * a temporary error. Instead, provide a `gboolean *` out parameter. |
358 | * There are functions in GLib itself such as g_key_file_has_key() that |
359 | * are hard to use because of this. If %FALSE is returned, the error must |
360 | * be set to a non-%NULL value. One exception to this is that in situations |
361 | * that are already considered to be undefined behaviour (such as when a |
362 | * g_return_val_if_fail() check fails), the error need not be set. |
363 | * Instead of checking separately whether the error is set, callers |
364 | * should ensure that they do not provoke undefined behaviour, then |
365 | * assume that the error will be set on failure. |
366 | * |
367 | * - A %NULL return value is also frequently used to mean that an error |
368 | * occurred. You should make clear in your documentation whether %NULL |
369 | * is a valid return value in non-error cases; if %NULL is a valid value, |
370 | * then users must check whether an error was returned to see if the |
371 | * function succeeded. |
372 | * |
373 | * - When implementing a function that can report errors, you may want |
374 | * to add a check at the top of your function that the error return |
375 | * location is either %NULL or contains a %NULL error (e.g. |
376 | * `g_return_if_fail (error == NULL || *error == NULL);`). |
377 | * |
378 | * ## Extended #GError Domains # {#gerror-extended-domains} |
379 | * |
380 | * Since GLib 2.68 it is possible to extend the #GError type. This is |
381 | * done with the G_DEFINE_EXTENDED_ERROR() macro. To create an |
382 | * extended #GError type do something like this in the header file: |
383 | * |[<!-- language="C" --> |
384 | * typedef enum |
385 | * { |
386 | * MY_ERROR_BAD_REQUEST, |
387 | * } MyError; |
388 | * #define MY_ERROR (my_error_quark ()) |
389 | * GQuark my_error_quark (void); |
390 | * int |
391 | * my_error_get_parse_error_id (GError *error); |
392 | * const char * |
393 | * my_error_get_bad_request_details (GError *error); |
394 | * ]| |
395 | * and in implementation: |
396 | * |[<!-- language="C" --> |
397 | * typedef struct |
398 | * { |
399 | * int parse_error_id; |
400 | * char *bad_request_details; |
401 | * } MyErrorPrivate; |
402 | * |
403 | * static void |
404 | * my_error_private_init (MyErrorPrivate *priv) |
405 | * { |
406 | * priv->parse_error_id = -1; |
407 | * // No need to set priv->bad_request_details to NULL, |
408 | * // the struct is initialized with zeros. |
409 | * } |
410 | * |
411 | * static void |
412 | * my_error_private_copy (const MyErrorPrivate *src_priv, MyErrorPrivate *dest_priv) |
413 | * { |
414 | * dest_priv->parse_error_id = src_priv->parse_error_id; |
415 | * dest_priv->bad_request_details = g_strdup (src_priv->bad_request_details); |
416 | * } |
417 | * |
418 | * static void |
419 | * my_error_private_clear (MyErrorPrivate *priv) |
420 | * { |
421 | * g_free (priv->bad_request_details); |
422 | * } |
423 | * |
424 | * // This defines the my_error_get_private and my_error_quark functions. |
425 | * G_DEFINE_EXTENDED_ERROR (MyError, my_error) |
426 | * |
427 | * int |
428 | * my_error_get_parse_error_id (GError *error) |
429 | * { |
430 | * MyErrorPrivate *priv = my_error_get_private (error); |
431 | * g_return_val_if_fail (priv != NULL, -1); |
432 | * return priv->parse_error_id; |
433 | * } |
434 | * |
435 | * const char * |
436 | * my_error_get_bad_request_details (GError *error) |
437 | * { |
438 | * MyErrorPrivate *priv = my_error_get_private (error); |
439 | * g_return_val_if_fail (priv != NULL, NULL); |
440 | * g_return_val_if_fail (error->code != MY_ERROR_BAD_REQUEST, NULL); |
441 | * return priv->bad_request_details; |
442 | * } |
443 | * |
444 | * static void |
445 | * my_error_set_bad_request (GError **error, |
446 | * const char *reason, |
447 | * int error_id, |
448 | * const char *details) |
449 | * { |
450 | * MyErrorPrivate *priv; |
451 | * g_set_error (error, MY_ERROR, MY_ERROR_BAD_REQUEST, "Invalid request: %s", reason); |
452 | * if (error != NULL && *error != NULL) |
453 | * { |
454 | * priv = my_error_get_private (error); |
455 | * g_return_val_if_fail (priv != NULL, NULL); |
456 | * priv->parse_error_id = error_id; |
457 | * priv->bad_request_details = g_strdup (details); |
458 | * } |
459 | * } |
460 | * ]| |
461 | * An example of use of the error could be: |
462 | * |[<!-- language="C" --> |
463 | * gboolean |
464 | * send_request (GBytes *request, GError **error) |
465 | * { |
466 | * ParseFailedStatus *failure = validate_request (request); |
467 | * if (failure != NULL) |
468 | * { |
469 | * my_error_set_bad_request (error, failure->reason, failure->error_id, failure->details); |
470 | * parse_failed_status_free (failure); |
471 | * return FALSE; |
472 | * } |
473 | * |
474 | * return send_one (request, error); |
475 | * } |
476 | * ]| |
477 | * |
478 | * Please note that if you are a library author and your library |
479 | * exposes an existing error domain, then you can't make this error |
480 | * domain an extended one without breaking ABI. This is because |
481 | * earlier it was possible to create an error with this error domain |
482 | * on the stack and then copy it with g_error_copy(). If the new |
483 | * version of your library makes the error domain an extended one, |
484 | * then g_error_copy() called by code that allocated the error on the |
485 | * stack will try to copy more data than it used to, which will lead |
486 | * to undefined behavior. You must not stack-allocate errors with an |
487 | * extended error domain, and it is bad practice to stack-allocate any |
488 | * other #GErrors. |
489 | * |
490 | * Extended error domains in unloadable plugins/modules are not |
491 | * supported. |
492 | */ |
493 | |
494 | #include "config.h" |
495 | |
496 | #include "gvalgrind.h" |
497 | #include <string.h> |
498 | |
499 | #include "gerror.h" |
500 | |
501 | #include "ghash.h" |
502 | #include "glib-init.h" |
503 | #include "gslice.h" |
504 | #include "gstrfuncs.h" |
505 | #include "gtestutils.h" |
506 | #include "gthread.h" |
507 | |
508 | static GRWLock error_domain_global; |
509 | /* error_domain_ht must be accessed with error_domain_global |
510 | * locked. |
511 | */ |
512 | static GHashTable *error_domain_ht = NULL; |
513 | |
514 | void |
515 | g_error_init (void) |
516 | { |
517 | error_domain_ht = g_hash_table_new (NULL, NULL); |
518 | } |
519 | |
520 | typedef struct |
521 | { |
522 | /* private_size is already aligned. */ |
523 | gsize private_size; |
524 | GErrorInitFunc init; |
525 | GErrorCopyFunc copy; |
526 | GErrorClearFunc clear; |
527 | } ErrorDomainInfo; |
528 | |
529 | /* Must be called with error_domain_global locked. |
530 | */ |
531 | static inline ErrorDomainInfo * |
532 | error_domain_lookup (GQuark domain) |
533 | { |
534 | return g_hash_table_lookup (hash_table: error_domain_ht, |
535 | GUINT_TO_POINTER (domain)); |
536 | } |
537 | |
538 | /* Copied from gtype.c. */ |
539 | #define STRUCT_ALIGNMENT (2 * sizeof (gsize)) |
540 | #define ALIGN_STRUCT(offset) \ |
541 | ((offset + (STRUCT_ALIGNMENT - 1)) & -STRUCT_ALIGNMENT) |
542 | |
543 | static void |
544 | error_domain_register (GQuark error_quark, |
545 | gsize error_type_private_size, |
546 | GErrorInitFunc error_type_init, |
547 | GErrorCopyFunc error_type_copy, |
548 | GErrorClearFunc error_type_clear) |
549 | { |
550 | g_rw_lock_writer_lock (rw_lock: &error_domain_global); |
551 | if (error_domain_lookup (domain: error_quark) == NULL) |
552 | { |
553 | ErrorDomainInfo *info = g_new (ErrorDomainInfo, 1); |
554 | info->private_size = ALIGN_STRUCT (error_type_private_size); |
555 | info->init = error_type_init; |
556 | info->copy = error_type_copy; |
557 | info->clear = error_type_clear; |
558 | |
559 | g_hash_table_insert (hash_table: error_domain_ht, |
560 | GUINT_TO_POINTER (error_quark), |
561 | value: info); |
562 | } |
563 | else |
564 | { |
565 | const char *name = g_quark_to_string (quark: error_quark); |
566 | |
567 | g_critical ("Attempted to register an extended error domain for %s more than once" , name); |
568 | } |
569 | g_rw_lock_writer_unlock (rw_lock: &error_domain_global); |
570 | } |
571 | |
572 | /** |
573 | * g_error_domain_register_static: |
574 | * @error_type_name: static string to create a #GQuark from |
575 | * @error_type_private_size: size of the private error data in bytes |
576 | * @error_type_init: function initializing fields of the private error data |
577 | * @error_type_copy: function copying fields of the private error data |
578 | * @error_type_clear: function freeing fields of the private error data |
579 | * |
580 | * This function registers an extended #GError domain. |
581 | * |
582 | * @error_type_name should not be freed. @error_type_private_size must |
583 | * be greater than 0. |
584 | * |
585 | * @error_type_init receives an initialized #GError and should then initialize |
586 | * the private data. |
587 | * |
588 | * @error_type_copy is a function that receives both original and a copy |
589 | * #GError and should copy the fields of the private error data. The standard |
590 | * #GError fields are already handled. |
591 | * |
592 | * @error_type_clear receives the pointer to the error, and it should free the |
593 | * fields of the private error data. It should not free the struct itself though. |
594 | * |
595 | * Normally, it is better to use G_DEFINE_EXTENDED_ERROR(), as it |
596 | * already takes care of passing valid information to this function. |
597 | * |
598 | * Returns: #GQuark representing the error domain |
599 | * Since: 2.68 |
600 | */ |
601 | GQuark |
602 | g_error_domain_register_static (const char *error_type_name, |
603 | gsize error_type_private_size, |
604 | GErrorInitFunc error_type_init, |
605 | GErrorCopyFunc error_type_copy, |
606 | GErrorClearFunc error_type_clear) |
607 | { |
608 | GQuark error_quark; |
609 | |
610 | g_return_val_if_fail (error_type_name != NULL, 0); |
611 | g_return_val_if_fail (error_type_private_size > 0, 0); |
612 | g_return_val_if_fail (error_type_init != NULL, 0); |
613 | g_return_val_if_fail (error_type_copy != NULL, 0); |
614 | g_return_val_if_fail (error_type_clear != NULL, 0); |
615 | |
616 | error_quark = g_quark_from_static_string (string: error_type_name); |
617 | error_domain_register (error_quark, |
618 | error_type_private_size, |
619 | error_type_init, |
620 | error_type_copy, |
621 | error_type_clear); |
622 | return error_quark; |
623 | } |
624 | |
625 | /** |
626 | * g_error_domain_register: |
627 | * @error_type_name: string to create a #GQuark from |
628 | * @error_type_private_size: size of the private error data in bytes |
629 | * @error_type_init: function initializing fields of the private error data |
630 | * @error_type_copy: function copying fields of the private error data |
631 | * @error_type_clear: function freeing fields of the private error data |
632 | * |
633 | * This function registers an extended #GError domain. |
634 | * @error_type_name will be duplicated. Otherwise does the same as |
635 | * g_error_domain_register_static(). |
636 | * |
637 | * Returns: #GQuark representing the error domain |
638 | * Since: 2.68 |
639 | */ |
640 | GQuark |
641 | g_error_domain_register (const char *error_type_name, |
642 | gsize error_type_private_size, |
643 | GErrorInitFunc error_type_init, |
644 | GErrorCopyFunc error_type_copy, |
645 | GErrorClearFunc error_type_clear) |
646 | { |
647 | GQuark error_quark; |
648 | |
649 | g_return_val_if_fail (error_type_name != NULL, 0); |
650 | g_return_val_if_fail (error_type_private_size > 0, 0); |
651 | g_return_val_if_fail (error_type_init != NULL, 0); |
652 | g_return_val_if_fail (error_type_copy != NULL, 0); |
653 | g_return_val_if_fail (error_type_clear != NULL, 0); |
654 | |
655 | error_quark = g_quark_from_string (string: error_type_name); |
656 | error_domain_register (error_quark, |
657 | error_type_private_size, |
658 | error_type_init, |
659 | error_type_copy, |
660 | error_type_clear); |
661 | return error_quark; |
662 | } |
663 | |
664 | static GError * |
665 | g_error_allocate (GQuark domain, ErrorDomainInfo *out_info) |
666 | { |
667 | guint8 *allocated; |
668 | GError *error; |
669 | ErrorDomainInfo *info; |
670 | gsize private_size; |
671 | |
672 | g_rw_lock_reader_lock (rw_lock: &error_domain_global); |
673 | info = error_domain_lookup (domain); |
674 | if (info != NULL) |
675 | { |
676 | if (out_info != NULL) |
677 | *out_info = *info; |
678 | private_size = info->private_size; |
679 | g_rw_lock_reader_unlock (rw_lock: &error_domain_global); |
680 | } |
681 | else |
682 | { |
683 | g_rw_lock_reader_unlock (rw_lock: &error_domain_global); |
684 | if (out_info != NULL) |
685 | memset (s: out_info, c: 0, n: sizeof (*out_info)); |
686 | private_size = 0; |
687 | } |
688 | /* See comments in g_type_create_instance in gtype.c to see what |
689 | * this magic is about. |
690 | */ |
691 | #ifdef ENABLE_VALGRIND |
692 | if (private_size > 0 && RUNNING_ON_VALGRIND) |
693 | { |
694 | private_size += ALIGN_STRUCT (1); |
695 | allocated = g_slice_alloc0 (block_size: private_size + sizeof (GError) + sizeof (gpointer)); |
696 | *(gpointer *) (allocated + private_size + sizeof (GError)) = allocated + ALIGN_STRUCT (1); |
697 | VALGRIND_MALLOCLIKE_BLOCK (allocated + private_size, sizeof (GError) + sizeof (gpointer), 0, TRUE); |
698 | VALGRIND_MALLOCLIKE_BLOCK (allocated + ALIGN_STRUCT (1), private_size - ALIGN_STRUCT (1), 0, TRUE); |
699 | } |
700 | else |
701 | #endif |
702 | allocated = g_slice_alloc0 (block_size: private_size + sizeof (GError)); |
703 | |
704 | error = (GError *) (allocated + private_size); |
705 | return error; |
706 | } |
707 | |
708 | /* This function takes ownership of @message. */ |
709 | static GError * |
710 | g_error_new_steal (GQuark domain, |
711 | gint code, |
712 | gchar *message, |
713 | ErrorDomainInfo *out_info) |
714 | { |
715 | ErrorDomainInfo info; |
716 | GError *error = g_error_allocate (domain, out_info: &info); |
717 | |
718 | error->domain = domain; |
719 | error->code = code; |
720 | error->message = message; |
721 | |
722 | if (info.init != NULL) |
723 | info.init (error); |
724 | if (out_info != NULL) |
725 | *out_info = info; |
726 | |
727 | return error; |
728 | } |
729 | |
730 | /** |
731 | * g_error_new_valist: |
732 | * @domain: error domain |
733 | * @code: error code |
734 | * @format: printf()-style format for error message |
735 | * @args: #va_list of parameters for the message format |
736 | * |
737 | * Creates a new #GError with the given @domain and @code, |
738 | * and a message formatted with @format. |
739 | * |
740 | * Returns: a new #GError |
741 | * |
742 | * Since: 2.22 |
743 | */ |
744 | GError* |
745 | g_error_new_valist (GQuark domain, |
746 | gint code, |
747 | const gchar *format, |
748 | va_list args) |
749 | { |
750 | /* Historically, GError allowed this (although it was never meant to work), |
751 | * and it has significant use in the wild, which g_return_val_if_fail |
752 | * would break. It should maybe g_return_val_if_fail in GLib 4. |
753 | * (GNOME#660371, GNOME#560482) |
754 | */ |
755 | g_warn_if_fail (domain != 0); |
756 | g_warn_if_fail (format != NULL); |
757 | |
758 | return g_error_new_steal (domain, code, message: g_strdup_vprintf (format, args), NULL); |
759 | } |
760 | |
761 | /** |
762 | * g_error_new: |
763 | * @domain: error domain |
764 | * @code: error code |
765 | * @format: printf()-style format for error message |
766 | * @...: parameters for message format |
767 | * |
768 | * Creates a new #GError with the given @domain and @code, |
769 | * and a message formatted with @format. |
770 | * |
771 | * Returns: a new #GError |
772 | */ |
773 | GError* |
774 | g_error_new (GQuark domain, |
775 | gint code, |
776 | const gchar *format, |
777 | ...) |
778 | { |
779 | GError* error; |
780 | va_list args; |
781 | |
782 | g_return_val_if_fail (format != NULL, NULL); |
783 | g_return_val_if_fail (domain != 0, NULL); |
784 | |
785 | va_start (args, format); |
786 | error = g_error_new_valist (domain, code, format, args); |
787 | va_end (args); |
788 | |
789 | return error; |
790 | } |
791 | |
792 | /** |
793 | * g_error_new_literal: |
794 | * @domain: error domain |
795 | * @code: error code |
796 | * @message: error message |
797 | * |
798 | * Creates a new #GError; unlike g_error_new(), @message is |
799 | * not a printf()-style format string. Use this function if |
800 | * @message contains text you don't have control over, |
801 | * that could include printf() escape sequences. |
802 | * |
803 | * Returns: a new #GError |
804 | **/ |
805 | GError* |
806 | g_error_new_literal (GQuark domain, |
807 | gint code, |
808 | const gchar *message) |
809 | { |
810 | g_return_val_if_fail (message != NULL, NULL); |
811 | g_return_val_if_fail (domain != 0, NULL); |
812 | |
813 | return g_error_new_steal (domain, code, message: g_strdup (str: message), NULL); |
814 | } |
815 | |
816 | /** |
817 | * g_error_free: |
818 | * @error: a #GError |
819 | * |
820 | * Frees a #GError and associated resources. |
821 | */ |
822 | void |
823 | g_error_free (GError *error) |
824 | { |
825 | gsize private_size; |
826 | ErrorDomainInfo *info; |
827 | guint8 *allocated; |
828 | |
829 | g_return_if_fail (error != NULL); |
830 | |
831 | g_rw_lock_reader_lock (rw_lock: &error_domain_global); |
832 | info = error_domain_lookup (domain: error->domain); |
833 | if (info != NULL) |
834 | { |
835 | GErrorClearFunc clear = info->clear; |
836 | |
837 | private_size = info->private_size; |
838 | g_rw_lock_reader_unlock (rw_lock: &error_domain_global); |
839 | clear (error); |
840 | } |
841 | else |
842 | { |
843 | g_rw_lock_reader_unlock (rw_lock: &error_domain_global); |
844 | private_size = 0; |
845 | } |
846 | |
847 | g_free (mem: error->message); |
848 | allocated = ((guint8 *) error) - private_size; |
849 | /* See comments in g_type_free_instance in gtype.c to see what this |
850 | * magic is about. |
851 | */ |
852 | #ifdef ENABLE_VALGRIND |
853 | if (private_size > 0 && RUNNING_ON_VALGRIND) |
854 | { |
855 | private_size += ALIGN_STRUCT (1); |
856 | allocated -= ALIGN_STRUCT (1); |
857 | *(gpointer *) (allocated + private_size + sizeof (GError)) = NULL; |
858 | g_slice_free1 (block_size: private_size + sizeof (GError) + sizeof (gpointer), mem_block: allocated); |
859 | VALGRIND_FREELIKE_BLOCK (allocated + ALIGN_STRUCT (1), 0); |
860 | VALGRIND_FREELIKE_BLOCK (error, 0); |
861 | } |
862 | else |
863 | #endif |
864 | g_slice_free1 (block_size: private_size + sizeof (GError), mem_block: allocated); |
865 | } |
866 | |
867 | /** |
868 | * g_error_copy: |
869 | * @error: a #GError |
870 | * |
871 | * Makes a copy of @error. |
872 | * |
873 | * Returns: a new #GError |
874 | */ |
875 | GError* |
876 | g_error_copy (const GError *error) |
877 | { |
878 | GError *copy; |
879 | ErrorDomainInfo info; |
880 | |
881 | g_return_val_if_fail (error != NULL, NULL); |
882 | /* See g_error_new_valist for why these don't return */ |
883 | g_warn_if_fail (error->domain != 0); |
884 | g_warn_if_fail (error->message != NULL); |
885 | |
886 | copy = g_error_new_steal (domain: error->domain, |
887 | code: error->code, |
888 | message: g_strdup (str: error->message), |
889 | out_info: &info); |
890 | if (info.copy != NULL) |
891 | info.copy (error, copy); |
892 | |
893 | return copy; |
894 | } |
895 | |
896 | /** |
897 | * g_error_matches: |
898 | * @error: (nullable): a #GError |
899 | * @domain: an error domain |
900 | * @code: an error code |
901 | * |
902 | * Returns %TRUE if @error matches @domain and @code, %FALSE |
903 | * otherwise. In particular, when @error is %NULL, %FALSE will |
904 | * be returned. |
905 | * |
906 | * If @domain contains a `FAILED` (or otherwise generic) error code, |
907 | * you should generally not check for it explicitly, but should |
908 | * instead treat any not-explicitly-recognized error code as being |
909 | * equivalent to the `FAILED` code. This way, if the domain is |
910 | * extended in the future to provide a more specific error code for |
911 | * a certain case, your code will still work. |
912 | * |
913 | * Returns: whether @error has @domain and @code |
914 | */ |
915 | gboolean |
916 | g_error_matches (const GError *error, |
917 | GQuark domain, |
918 | gint code) |
919 | { |
920 | return error && |
921 | error->domain == domain && |
922 | error->code == code; |
923 | } |
924 | |
925 | #define ERROR_OVERWRITTEN_WARNING "GError set over the top of a previous GError or uninitialized memory.\n" \ |
926 | "This indicates a bug in someone's code. You must ensure an error is NULL before it's set.\n" \ |
927 | "The overwriting error message was: %s" |
928 | |
929 | /** |
930 | * g_set_error: |
931 | * @err: (out callee-allocates) (optional): a return location for a #GError |
932 | * @domain: error domain |
933 | * @code: error code |
934 | * @format: printf()-style format |
935 | * @...: args for @format |
936 | * |
937 | * Does nothing if @err is %NULL; if @err is non-%NULL, then *@err |
938 | * must be %NULL. A new #GError is created and assigned to *@err. |
939 | */ |
940 | void |
941 | g_set_error (GError **err, |
942 | GQuark domain, |
943 | gint code, |
944 | const gchar *format, |
945 | ...) |
946 | { |
947 | GError *new; |
948 | |
949 | va_list args; |
950 | |
951 | if (err == NULL) |
952 | return; |
953 | |
954 | va_start (args, format); |
955 | new = g_error_new_valist (domain, code, format, args); |
956 | va_end (args); |
957 | |
958 | if (*err == NULL) |
959 | *err = new; |
960 | else |
961 | { |
962 | g_warning (ERROR_OVERWRITTEN_WARNING, new->message); |
963 | g_error_free (error: new); |
964 | } |
965 | } |
966 | |
967 | /** |
968 | * g_set_error_literal: |
969 | * @err: (out callee-allocates) (optional): a return location for a #GError |
970 | * @domain: error domain |
971 | * @code: error code |
972 | * @message: error message |
973 | * |
974 | * Does nothing if @err is %NULL; if @err is non-%NULL, then *@err |
975 | * must be %NULL. A new #GError is created and assigned to *@err. |
976 | * Unlike g_set_error(), @message is not a printf()-style format string. |
977 | * Use this function if @message contains text you don't have control over, |
978 | * that could include printf() escape sequences. |
979 | * |
980 | * Since: 2.18 |
981 | */ |
982 | void |
983 | g_set_error_literal (GError **err, |
984 | GQuark domain, |
985 | gint code, |
986 | const gchar *message) |
987 | { |
988 | if (err == NULL) |
989 | return; |
990 | |
991 | if (*err == NULL) |
992 | *err = g_error_new_literal (domain, code, message); |
993 | else |
994 | g_warning (ERROR_OVERWRITTEN_WARNING, message); |
995 | } |
996 | |
997 | /** |
998 | * g_propagate_error: |
999 | * @dest: (out callee-allocates) (optional) (nullable): error return location |
1000 | * @src: (transfer full): error to move into the return location |
1001 | * |
1002 | * If @dest is %NULL, free @src; otherwise, moves @src into *@dest. |
1003 | * The error variable @dest points to must be %NULL. |
1004 | * |
1005 | * @src must be non-%NULL. |
1006 | * |
1007 | * Note that @src is no longer valid after this call. If you want |
1008 | * to keep using the same GError*, you need to set it to %NULL |
1009 | * after calling this function on it. |
1010 | */ |
1011 | void |
1012 | g_propagate_error (GError **dest, |
1013 | GError *src) |
1014 | { |
1015 | g_return_if_fail (src != NULL); |
1016 | |
1017 | if (dest == NULL) |
1018 | { |
1019 | g_error_free (error: src); |
1020 | return; |
1021 | } |
1022 | else |
1023 | { |
1024 | if (*dest != NULL) |
1025 | { |
1026 | g_warning (ERROR_OVERWRITTEN_WARNING, src->message); |
1027 | g_error_free (error: src); |
1028 | } |
1029 | else |
1030 | *dest = src; |
1031 | } |
1032 | } |
1033 | |
1034 | /** |
1035 | * g_clear_error: |
1036 | * @err: a #GError return location |
1037 | * |
1038 | * If @err or *@err is %NULL, does nothing. Otherwise, |
1039 | * calls g_error_free() on *@err and sets *@err to %NULL. |
1040 | */ |
1041 | void |
1042 | g_clear_error (GError **err) |
1043 | { |
1044 | if (err && *err) |
1045 | { |
1046 | g_error_free (error: *err); |
1047 | *err = NULL; |
1048 | } |
1049 | } |
1050 | |
1051 | G_GNUC_PRINTF(2, 0) |
1052 | static void |
1053 | g_error_add_prefix (gchar **string, |
1054 | const gchar *format, |
1055 | va_list ap) |
1056 | { |
1057 | gchar *oldstring; |
1058 | gchar *prefix; |
1059 | |
1060 | prefix = g_strdup_vprintf (format, args: ap); |
1061 | oldstring = *string; |
1062 | *string = g_strconcat (string1: prefix, oldstring, NULL); |
1063 | g_free (mem: oldstring); |
1064 | g_free (mem: prefix); |
1065 | } |
1066 | |
1067 | /** |
1068 | * g_prefix_error: |
1069 | * @err: (inout) (optional) (nullable): a return location for a #GError |
1070 | * @format: printf()-style format string |
1071 | * @...: arguments to @format |
1072 | * |
1073 | * Formats a string according to @format and prefix it to an existing |
1074 | * error message. If @err is %NULL (ie: no error variable) then do |
1075 | * nothing. |
1076 | * |
1077 | * If *@err is %NULL (ie: an error variable is present but there is no |
1078 | * error condition) then also do nothing. |
1079 | * |
1080 | * Since: 2.16 |
1081 | */ |
1082 | void |
1083 | g_prefix_error (GError **err, |
1084 | const gchar *format, |
1085 | ...) |
1086 | { |
1087 | if (err && *err) |
1088 | { |
1089 | va_list ap; |
1090 | |
1091 | va_start (ap, format); |
1092 | g_error_add_prefix (string: &(*err)->message, format, ap); |
1093 | va_end (ap); |
1094 | } |
1095 | } |
1096 | |
1097 | /** |
1098 | * g_propagate_prefixed_error: |
1099 | * @dest: error return location |
1100 | * @src: error to move into the return location |
1101 | * @format: printf()-style format string |
1102 | * @...: arguments to @format |
1103 | * |
1104 | * If @dest is %NULL, free @src; otherwise, moves @src into *@dest. |
1105 | * *@dest must be %NULL. After the move, add a prefix as with |
1106 | * g_prefix_error(). |
1107 | * |
1108 | * Since: 2.16 |
1109 | **/ |
1110 | void |
1111 | g_propagate_prefixed_error (GError **dest, |
1112 | GError *src, |
1113 | const gchar *format, |
1114 | ...) |
1115 | { |
1116 | g_propagate_error (dest, src); |
1117 | |
1118 | if (dest) |
1119 | { |
1120 | va_list ap; |
1121 | |
1122 | g_assert (*dest != NULL); |
1123 | va_start (ap, format); |
1124 | g_error_add_prefix (string: &(*dest)->message, format, ap); |
1125 | va_end (ap); |
1126 | } |
1127 | } |
1128 | |