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17 /*!
18 * ======== Error ========
19 * Runtime error manager
20 *
21 * The `Error` module provides mechanisms for raising, checking, and
22 * handling errors in a program. You can configure it via the
23 * `{@link Error#policy Error.policy}` and
24 * `{@link Error#raiseHook Error.raiseHook}` configuration parameters.
25 *
26 * Modules may define specific error types and reference these when
27 * raising an error. Each error type has a custom error message and
28 * can be parameterized with up to `{@link #NUMARGS}` arguments. A
29 * generic error type is provided for raising errors when not in a module.
30 *
31 * Use the `{@link #check Error_check()}` function to determine if an
32 * error has been raised. It is important to understand that it is the
33 * caller's responsibility to check the error block after calling a
34 * function that takes an error block as an argument. Otherwise, a raised
35 * error may go undetected, which could compromise the integrity of the
36 * system. For example:
37 *
38 * @p(code)
39 * Task_create(..., &eb);
40 *
41 * if (Error_check(&eb)) {
42 * ...an error has been raised...
43 * }
44 * @p
45 *
46 * The `{@link #raiseHook Error.raiseHook}` configuration parameter allows
47 * a configured function to be invoked when any error is raised. This
48 * function is passed a pointer to the error's error block and makes it
49 * easy to manage all errors from a common point. For example, you can
50 * trap any error (fatal or not) by simply setting a breakpoint in this
51 * function. You can use the following functions to extract information
52 * from an error block.
53 *
54 * @p(blist)
55 * - `{@link #getData Error_getData()}`
56 * - `{@link #getCode Error_getCode()}`
57 * - `{@link #getId Error_getId()}`
58 * - `{@link #getMsg Error_getMsg()}`
59 * - `{@link #getSite Error_getSite()}`
60 * @p
61 *
62 * The Error module provides facilities for handling errors, but the Log
63 * module also provides features for logging error events. These are separate
64 * concepts; however, to ensure that users do not have to both raise and log
65 * an error, the Error module will automatically log an error event when one
66 * is raised. The Error module logs the standard {@link Log#L_error} event,
67 * passing it the error message and arguments.
68 *
69 * The error event is logged to the Error module's logger using the Error
70 * module's diags mask. Logging of errors is enabled by default in the diags
71 * mask, but the event will not be logged unless a logger is configured for
72 * the Error module as well.
73 *
74 * To make the error event appear as though it is coming from the module which
75 * called Error_raise, the event is logged with the caller's module id and
76 * with the caller's call site information.
77 *
78 * @a(Examples)
79 * Example 1: The following example shows how a module, named ModA,
80 * defines a custom error type and shows how this error is raised by
81 * the module. The module defines an `Id` of `E_notEven` in its module
82 * specification file (in this case, `ModA.xdc`). The error's message
83 * string takes only one argument. The module also defines a `mayFail()`
84 * function that takes an error block. In the module's C source file,
85 * the function checks for the error condition and raises the error if
86 * needed.
87 *
88 * This is part of ModA's XDC specification file for the module:
89 *
90 * @p(code)
91 * config xdc.runtime.Error.Id E_notEven = {
92 * msg: "expected an even number (%d)"
93 * };
94 *
95 * Void mayFail(Int x, xdc.runtime.Error.Block *eb);
96 * @p
97 *
98 * This is part of the C code for the module:
99 *
100 * @p(code)
101 * Void ModA_mayFail(Int x, Error_Block *eb)
102 * {
103 * if ((x % 2) != 0) {
104 * Error_raise(eb, ModA_E_notEven, x, 0);
105 * ...add error handling code here...
106 * return;
107 * }
108 * ...
109 * }
110 * @p
111 *
112 * @p(html)
113 * <hr />
114 * @p
115 *
116 * Example 2: The following C code supplies an error block to a function
117 * that requires one and tests the error block to see if the function
118 * raised an error. Note that an error block must be initialized before
119 * it can be used and same error block may be passed to several functions.
120 *
121 * @p(code)
122 * #include <xdc/runtime/Error.h>
123 * #include <ti/sysbios/knl/Task.h>
124 * Error_Block eb;
125 * Task_Handle tsk;
126 *
127 * Error_init(&eb);
128 * tsk = Task_create(..., &eb);
129 *
130 * if (Error_check(&eb)) {
131 * ...an error has been raised...
132 * }
133 * @p
134 *
135 * @p(html)
136 * <hr />
137 * @p
138 *
139 * Example 3: The following C code shows that you may pass `NULL` to a
140 * function requiring an error block. In this case, if the function
141 * raises an error, the program is aborted (via
142 * `{@link System#abort xdc_runtime_System_abort()}`), thus execution
143 * control will never return to the caller.
144 *
145 * @p(code)
146 * #include <xdc/runtime/Error.h>
147 * #include <ti/sysbios/knl/Task.h>
148 *
149 * tsk = Task_create(..., NULL);
150 * ...will never get here if an error was raised in Task_create...
151 * @p
152 *
153 * @p(html)
154 * <hr />
155 * @p
156 *
157 * Example 4: The following C code shows how to write a function that
158 * is not part of a module and that takes an error block and raises
159 * the generic error type provided by the Error module. Note, if the
160 * caller passes `NULL` for the error block or if the error policy is
161 * `{@link #Policy TERMINATE}`, then the call to
162 * `{@link #raise Error_raise()}` will call
163 * `{@link System#abort xdc_runtime_System_abort()}` and never return.
164 *
165 * @p(code)
166 * #include <xdc/runtime/Error.h>
167 *
168 * Void myFunc(..., Error_Block *eb)
169 * {
170 * ...
171 *
172 * if (...error condition detected...) {
173 * String myErrorMsg = "my custom error message";
174 * Error_raise(eb, Error_E_generic, myErrorMsg, 0);
175 * ...add error handling code here...
176 * return;
177 * }
178 * }
179 * @p
180 */
181
182 module Error {
183
184 /*!
185 * ======== Policy ========
186 * Error handling policies
187 *
188 * Regardless of the current policy in use, raising an error by
189 * calling `{@link #raise Error_raise}` will always invoke the
190 * error raise hook function assigned to the
191 * `{@link #raiseHook Error.raiseHook}` configuration parameter.
192 *
193 * @field(TERMINATE) All raised errors are fatal. A call to
194 * `{@link #raise Error_raise}` will never return to the caller.
195 *
196 * @field(UNWIND) Errors are returned to the caller. A call to
197 * `{@link #raise Error_raise}` will return back to the caller.
198 */
199 enum Policy {
200 TERMINATE,
201 UNWIND
202 };
203
204 /*!
205 * ======== Desc ========
206 * Error descriptor
207 *
208 * Each type of error is defined with an error descriptor. This
209 * structure groups common information about the errors of this type.
210 *
211 * @field(msg) The error message using a `printf` style format string,
212 * but limited to `{@link #NUMARGS}` arguments.
213 * This format string together with the two arguments passed
214 * to `Error_raise`` are used to create a human readable
215 * error message.
216 *
217 * @field(code) A user assignable code, 0 by default. The user may
218 * optionally set this field during config to give the
219 * error a well-known numeric code.
220 */
221 metaonly struct Desc {
222 String msg;
223 UInt16 code;
224 };
225
226 /*!
227 * ======== Id ========
228 * Error identifier
229 *
230 * Each type of error raised is defined with a metaonly
231 * `{@link Error#Desc}`. An `Error_Id` is a 32-bit target value that
232 * encodes the information in the `Desc`. Target programs use
233 * `Error_Id` values to "raise" and check for specific errors.
234 *
235 * @a(Warning) `{@link #Id}` values may vary among different
236 * configurations of an application. For example, the addition of a
237 * new module to a program may result in a different absolute value for
238 * `{@link #E_generic}`. If you need error numbers that remain
239 * invariant, use the user definable `{@link #Desc Desc.code}` field.
240 */
241 @Encoded typedef Desc Id;
242
243 /*!
244 * ======== HookFxn ========
245 * Function called whenever an error is raised
246 *
247 * The first parameter and only parameter passed to this function is a
248 * pointer to an `Error_Block`. Even if the client passes a `NULL` error
249 * block pointer to `{@link #raise Error_raise}`, this parameter passed
250 * to this "hook" function is always `non-NULL`.
251 */
252 typedef Void (*HookFxn)(Block *);
253
254 /*!
255 * ======== NUMARGS ========
256 * Maximum number of arguments supported by an error
257 */
258 const Int NUMARGS = 2;
259
260 /*!
261 * ======== Data ========
262 * Error args
263 *
264 * The two arguments (arg1, arg2) passed to `{@link #raise}` are
265 * stored in one of these arrays within the associated Error_Block.
266 * To access these arguments use `{@link #getData}` to obtain a
267 * pointer to the Error_Block's Data array.
268 *
269 * @see #getData
270 */
271 struct Data {
272 IArg arg[NUMARGS];
273 }
274
275 /*!
276 * ======== Block ========
277 * Error block
278 *
279 * An opaque structure used to store information about errors once raised.
280 * This structure must be initialized via `{@link #init Error_init()}`
281 * before being used for the first time.
282 */
283 @Opaque struct Block {
284 UInt16 unused;
285 Data data;
286 Id id;
287 String msg;
288 Types.Site site;
289 IArg xtra[4];
290 };
291
292 /*!
293 * ======== E_generic ========
294 * Generic error
295 *
296 * This error takes advantage of the $S specifier to allow for recursive
297 * formatting of the error message passed to error raise.
298 *
299 * For example, the following is possible:
300 * @p(code)
301 * Error_raise(eb, Error_E_generic, "Error occurred, code: %d", code);
302 * @p
303 *
304 * @see System#extendedFormats
305 * @see System#printf
306 */
307 config Id E_generic = {msg: "%$S"};
308
309 /*!
310 * ======== E_memory ========
311 * Out of memory error
312 *
313 * The first parameter must be the heap instance handle. The second
314 * parameter is the size of the object for which the allocation failed.
315 */
316 config Id E_memory = {msg: "out of memory: heap=0x%x, size=%u"};
317
318 /*!
319 * ======== E_msgCode ========
320 * Generic error that displays a string and a numeric value
321 */
322 config Id E_msgCode = {msg: "%s 0x%x"};
323
324 /*!
325 * ======== policy ========
326 * System-wide error handling policy
327 */
328 config Policy policy = UNWIND;
329
330 /*!
331 * ======== raiseHook ========
332 * The function to call whenever an error is raised
333 *
334 * This function is always called when an error is raised, even if the
335 * `Error` policy is `{@link #Policy TERMINATE}`. In rare cases, it is
336 * possible that a raised error does not trigger a call to `raiseHook`;
337 * see `{@link #maxDepth}`.
338 *
339 * By default, this function is set to `{@link #print Error_print}`
340 * which causes the error to be formatted and output via
341 * `{@link xdc.runtime.System#aprintf System_printf}`.
342 *
343 * @see #maxDepth
344 * @see #HookFxn
345 * @see #print
346 */
347 config HookFxn raiseHook = Error.print;
348
349 /*!
350 * ======== maxDepth ========
351 * Maximum number of concurrent calls to `{@link #raiseHook}`
352 *
353 * To prevent errors that occur in the raiseHook function from
354 * causing an infinite recursion, the maximum number of concurrent
355 * calls to `{@link #raiseHook}` is limited by `Error_maxDepth`. If
356 * the number of concurrent calls exceeds `Error_maxDepth`, the
357 * `raiseHook` function is not called.
358 *
359 * In multi-threaded systems, errors raised by separate threads may
360 * be detected as recursive calls to `raiseHook`. So, setting
361 * `Error.maxDepth` to a small value may - in rare instances - result in
362 * `errorHook` not being called for some raised errors.
363 *
364 * If it is important that all raised errors trigger a call to the
365 * `raiseHook` function, set `Error.maxDepth` to an impossibly large
366 * number (0xffff) and either ensure that the raise hook never calls a
367 * function that can raise an error or add checks in `raiseHook` to
368 * protect against "double faults".
369 */
370 config UInt16 maxDepth = 16;
371
372 /*!
373 * ======== check ========
374 * Return TRUE if an error was raised
375 *
376 * @param(eb) pointer to an `Error_Block` or `NULL`
377 *
378 * @a(returns)
379 * If `eb` is non-`NULL` and `{@link #policy Error.policy} == UNWIND` and
380 * an error was raised on `eb`, this function returns `TRUE`. Otherwise,
381 * it returns `FALSE`.
382 */
383 Bool check(Block *eb);
384
385 /*!
386 * ======== getData ========
387 * Get an error's argument list
388 *
389 * @param(eb) non-`NULL` pointer to an `Error_Block`
390 *
391 * @a(returns)
392 * `getData` returns an array of type `{@link #Data}` with
393 * `{@link #NUMARGS}` elements containing the arguments provided
394 * at the time the error was raised.
395 *
396 * @see #raise
397 */
398 Data *getData(Block *eb);
399
400 /*!
401 * ======== getCode ========
402 * Get an error's code
403 *
404 * @param(eb) non-`NULL` pointer to an `Error_Block`
405 *
406 * @a(returns)
407 * `getCode` returns the error code associated with this error block.
408 *
409 * @see #raise
410 * @see #Desc
411 */
412 UInt16 getCode(Block *eb);
413
414 /*!
415 * ======== getId ========
416 * Get an error's id
417 *
418 * @param(eb) non-`NULL` pointer to an `Error_Block`
419 *
420 * @a(Warning)
421 * `Error_Id` values may vary among different configurations
422 * of an application. For example, the addition of a new module to a
423 * program may result in a different absolute value for
424 * `{@link #E_generic}`. If you need error numbers that remain
425 * invariant, use the user definable `{@link #Desc Desc.code}` field.
426 *
427 * @see #raise
428 * @see #Desc
429 */
430 Id getId(Block *eb);
431
432 /*!
433 * ======== getMsg ========
434 * Get an error's "printf" format string
435 *
436 * @param(eb) non-`NULL` pointer to an `Error_Block`
437 *
438 * @see #raise
439 * @see #Desc
440 */
441 String getMsg(Block *eb);
442
443 /*!
444 * ======== getSite ========
445 * Get an error's call site info
446 *
447 * @param(eb) non-`NULL` pointer to an `Error_Block`
448 *
449 * @a(returns)
450 * `getSite` returns a pointer to an initialized
451 * `{@link Types#Site Types.Site}` structure. However, in the
452 * event that the call site was compiled with `xdc_FILE` defined to
453 * be `NULL` (to minimize string space overhead) the `file`
454 * field may be set to `NULL`.
455 *
456 * @see #raise
457 * @see #Desc
458 */
459 Types.Site *getSite(Block *eb);
460
461 /*!
462 * ======== idToCode ========
463 * Extract the user's error code associated with an `Error_Id`
464 *
465 * @param(id) `Error_Id` from which to extract the user defined
466 * code
467 * @_nodoc
468 */
469 @Macro UInt16 idToCode(Id id);
470
471 /*!
472 * ======== idToUid ========
473 * Extract the unique error id associated with an `Error_Id`
474 *
475 * @param(id) `Error_Id` from which to extract the system unique
476 * id associated with the specified `Error_Id`
477 * @_nodoc
478 */
479 @Macro UInt16 idToUid(Id id);
480
481 /*!
482 * ======== init ========
483 * Put an error block into its initial state
484 *
485 * To ensure reliable error detection, clients must call `init` for
486 * an `Error_Block` prior to any use.
487 *
488 * If the same Error Block is used multiple times, only the last error
489 * raised is retained.
490 *
491 * @param(eb) pointer to an `Error_Block` or `NULL`
492 *
493 * If `eb` is `NULL` this function simply returns.
494 */
495 Void init(Block *eb);
496
497 /*!
498 * ======== print ========
499 * Print error using System.printf()
500 *
501 * This function prints the error using `System_printf()`. The output
502 * is on a single line terminated with a new line character and has the
503 * following form:
504 * @p(code)
505 * <site>: <file>, line <line_num>: <err_msg>
506 * @p
507 * where `<site>` is the module that raised the error, `<file>` and
508 * `<line_num>` are the file and line number of the containing the call
509 * site of the `Error_raise()`, and `<err_msg>` is the error message
510 * rendered with the arguments associated with the error.
511 *
512 * @param(eb) pointer to an `Error_Block` or `NULL`
513 *
514 * If `eb` is `NULL` this function simply returns with no output.
515 *
516 * @a(Warning)
517 * This function is not protected by a gate and, as a result,
518 * if two threads call this method concurrently, the output of the two
519 * calls will be intermingled. To prevent intermingled error output,
520 * you can either wrap all calls to this method with an appropriate
521 * `Gate_enter`/`Gate_leave` pair or simply ensure that only one
522 * thread in the system ever calls this method.
523 */
524 Void print(Block *eb);
525
526 /*!
527 * ======== raise ========
528 * Raise an error
529 *
530 * This function is used to raise an `Error` by writing call site,
531 * error ID, and error argument information into the `Error_Block`
532 * pointed to by `eb`.
533 *
534 * If `Error_raise` is called more than once on an `Error_Block` object,
535 * the previous error information is overwritten; only the last error
536 * is retained in the `Error_Block` object.
537 *
538 * In all cases, any configured `{@link #raiseHook Error.raiseHook}`
539 * function is called with a non-`NULL` pointer to a fully
540 * initialized `Error_Block` object.
541 *
542 * @param(eb) pointer to an `Error_Block` or `NULL`
543 *
544 * If `eb` is `NULL` or `{@link #policy Error.policy} == TERMINATE`,
545 * this function does not return to the caller; after calling any
546 * configured `{@link #raiseHook}`, `System_abort` is called with the
547 * string `"xdc.runtime.Error.raise: terminating execution\n"`.
548 *
549 * @param(id) the error to raise
550 *
551 * This pointer identifies the class of error being raised;
552 * the error class indicates how to interpret any subsequent
553 * arguments passed to `{@link #raise}`.
554 *
555 * @param(arg1) error's first argument
556 *
557 * The argument interpreted by the first control character
558 * in the error message format string. It is ignored if not needed.
559 *
560 * @param(arg2) error's second argument
561 *
562 * The argument interpreted by the second control character
563 * in the error message format string. It is ignored if not needed.
564 */
565 @Macro Void raise(Block *eb, Id id, IArg arg1, IArg arg2);
566
567 /*! @_nodoc */
568 Void raiseX(Block *eb, Types.ModuleId mod, String file, Int line, Id id,
569 IArg arg1, IArg arg2);
570
571 internal:
572
573 struct Module_State {
574 UInt16 count;
575 };
576
577 }
578 579 580
581