1 /* ex - Exception Handling */
3 /* Copyright (c) 2005-2015. The SimGrid Team.
4 * All rights reserved. */
6 /* Copyright (c) 2002-2004 Ralf S. Engelschall <rse@engelschall.com> */
7 /* Copyright (c) 2002-2004 The OSSP Project <http://www.ossp.org/> */
8 /* Copyright (c) 2002-2004 Cable & Wireless <http://www.cw.com/> */
9 /* All rights reserved. */
11 /* This code is inspirated from the OSSP version (as retrieved back in 2004)*/
12 /* It was heavily modified to fit the SimGrid framework. */
14 /* The OSSP version has the following copyright notice:
15 ** OSSP ex - Exception Handling
16 ** Copyright (c) 2002-2004 Ralf S. Engelschall <rse@engelschall.com>
17 ** Copyright (c) 2002-2004 The OSSP Project <http://www.ossp.org/>
18 ** Copyright (c) 2002-2004 Cable & Wireless <http://www.cw.com/>
20 ** This file is part of OSSP ex, an exception handling library
21 ** which can be found at http://www.ossp.org/pkg/lib/ex/.
23 ** Permission to use, copy, modify, and distribute this software for
24 ** any purpose with or without fee is hereby granted, provided that
25 ** the above copyright notice and this permission notice appear in all
28 ** THIS SOFTWARE IS PROVIDED `AS IS'' AND ANY EXPRESSED OR IMPLIED
29 ** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
30 ** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 ** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
32 ** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
35 ** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
36 ** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
37 ** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
38 ** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 /* The extensions made for the SimGrid project can either be distributed */
43 /* under the same license, or under the LGPL v2.1 */
50 #include "xbt/sysdep.h"
52 #include "xbt/virtu.h"
56 /*-*-* Emergency debuging: define this when the exceptions get crazy *-*-*/
61 # define MAYDAY_SAVE(m) printf("%d %s:%d save %p\n", \
62 xbt_getpid(), __FILE__, __LINE__, \
65 # define MAYDAY_RESTORE(m) printf("%d %s:%d restore %p\n", \
66 xbt_getpid(), __FILE__, __LINE__, \
69 # define MAYDAY_CATCH(e) printf("%d %s:%d Catched '%s'\n", \
70 xbt_getpid(), __FILE__, __LINE__, \
74 # define MAYDAY_SAVE(m)
75 # define MAYDAY_RESTORE(m)
76 # define MAYDAY_CATCH(e)
78 /*-*-* end of debugging stuff *-*-*/
79 #if defined(__EX_MCTX_MCSC__)
80 #include <ucontext.h> /* POSIX.1 ucontext(3) */
81 #define __ex_mctx_struct ucontext_t uc;
82 #define __ex_mctx_save(mctx) (getcontext(&(mctx)->uc) == 0)
83 #define __ex_mctx_restored(mctx) /* noop */
84 #define __ex_mctx_restore(mctx) (void)setcontext(&(mctx)->uc)
85 #elif defined(__EX_MCTX_SSJLJ__)
86 #include <setjmp.h> /* POSIX.1 sigjmp_buf(3) */
87 #define __ex_mctx_struct sigjmp_buf jb;
88 #define __ex_mctx_save(mctx) (sigsetjmp((mctx)->jb, 1) == 0)
89 #define __ex_mctx_restored(mctx) /* noop */
90 #define __ex_mctx_restore(mctx) (void)siglongjmp((mctx)->jb, 1)
91 #elif defined(__EX_MCTX_SJLJ__) || !defined(__EX_MCTX_CUSTOM__) || defined(__EX_MAYDAY)
92 #include <setjmp.h> /* ISO-C jmp_buf(3) */
93 #define __ex_mctx_struct jmp_buf jb;
94 #define __ex_mctx_save(mctx) ( MAYDAY_SAVE(mctx) setjmp((mctx)->jb) == 0)
95 #define __ex_mctx_restored(mctx) /* noop */
96 #define __ex_mctx_restore(mctx) ( MAYDAY_RESTORE(mctx) (void)longjmp((mctx)->jb, 1))
98 /* declare the machine context type */
100 __ex_mctx_struct} __ex_mctx_t;
102 /** @addtogroup XBT_ex
103 * @brief A set of macros providing exception a la C++ in ANSI C (grounding feature)
105 * This module is a small ISO-C++ style exception handling library
106 * for use in the ISO-C language. It allows you to use the paradigm
107 * of throwing and catching exceptions in order to reduce the amount
108 * of error handling code without hindering program robustness.
110 * This is achieved by directly transferring exceptional return codes
111 * (and the program control flow) from the location where the exception
112 * is raised (throw point) to the location where it is handled (catch
113 * point) -- usually from a deeply nested sub-routine to a parent
114 * routine. All intermediate routines no longer have to make sure that
115 * the exceptional return codes from sub-routines are correctly passed
116 * back to the parent.
118 * These features are brought to you by a modified version of the libex
119 * library, one of the numerous masterpiece of Ralf S. Engelschall.
121 * \htmlonly <div class="toc">\endhtmlonly
123 * @section XBT_ex_toc TABLE OF CONTENTS
125 * - \ref XBT_ex_intro
127 * - \ref XBT_ex_pitfalls
129 * \htmlonly </div> \endhtmlonly
131 * @section XBT_ex_intro DESCRIPTION
133 * In SimGrid, an exception is a triple <\a msg , \a category , \a value>
134 * where \a msg is a human-readable text describing the exceptional
135 * condition, \a code an integer describing what went wrong and \a value
136 * providing a sort of sub-category. (this is different in the original libex).
138 * @section XBT_ex_base BASIC USAGE
140 * \em TRY \b TRIED_BLOCK [\em TRY_CLEANUP \b CLEANUP_BLOCK] \em CATCH (variable) \b CATCH_BLOCK
142 * This is the primary syntactical construct provided. It is modeled after the
143 * ISO-C++ try-catch clause and should sound familiar to most of you.
145 * Any exception thrown directly from the TRIED_BLOCK block or from called
146 * subroutines is caught. Cleanups which must be done after this block
147 * (whenever an exception arose or not) should be placed into the optionnal
148 * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should
149 * be placed into the (mandatory) CATCH_BLOCK.
152 * In absence of exception, the control flow goes into the blocks TRIED_BLOCK
153 * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored.
155 * When an exception is thrown, the control flow goes through the following
156 * blocks: TRIED_BLOCK (up to the statement throwing the exception),
157 * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a
158 * variable for inspection inside the CATCH_BLOCK. This variable must be
159 * declared in the outter scope, but its value is only valid within the
163 * - TRY, CLEANUP and CATCH cannot be used separately, they work
164 * only in combination and form a language clause as a whole.
165 * - In contrast to the syntax of other languages (such as C++ or Jave) there
166 * is only one CATCH block and not multiple ones (all exceptions are
167 * of the same \em xbt_ex_t C type).
168 * - the variable of CATCH can naturally be reused in subsequent
170 * - it is possible to nest TRY clauses.
172 * The TRY block is a regular ISO-C language statement block, but
174 * <center><b>it is not
175 * allowed to jump into it via "goto" or longjmp(3) or out of it via "break",
176 * "return", "goto" or longjmp(3)</b>.</center>
178 * This is because there is some hidden setup and
179 * cleanup that needs to be done regardless of whether an exception is
180 * caught. Bypassing these steps will break the exception handling facility.
181 * The symptom are likely to be a segfault at the next exception raising point,
182 * ie far away from the point where you did the mistake. Finding the problem can
183 * reveal challenging, unfortunately.
185 * The CLEANUP and CATCH blocks are regular ISO-C language statement
186 * blocks without any restrictions. You are even allowed to throw (and, in the
187 * CATCH block, to re-throw) exceptions.
189 * There is one subtle detail you should remember about TRY blocks:
190 * Variables used in the CLEANUP or CATCH clauses must be declared with
191 * the storage class "volatile", otherwise they might contain outdated
192 * information if an exception is thrown.
195 * This is because you usually do not know which commands in the TRY
196 * were already successful before the exception was thrown (logically speaking)
197 * and because the underlying ISO-C setjmp(3) facility applies those
198 * restrictions (technically speaking). As a matter of fact, value changes
199 * between the TRY and the THROW may be discarded if you forget the
200 * "volatile" keyword.
202 * \section XBT_ex_pitfalls PROGRAMMING PITFALLS
204 * Exception handling is a very elegant and efficient way of dealing with
205 * exceptional situation. Nevertheless it requires additional discipline in
206 * programming and there are a few pitfalls one must be aware of. Look the
207 * following code which shows some pitfalls and contains many errors (assuming
208 * a mallocex() function which throws an exception if malloc(3) fails):
212 * \until end_of_bad_example
214 * This example raises a few issues:
215 * -# \b variable \b scope \n
216 * Variables which are used in the CLEANUP or CATCH clauses must be
217 * declared before the TRY clause, otherwise they only exist inside the
218 * TRY block. In the example above, cp1, cp2 and cp3 only exist in the
219 * TRY block and are invisible from the CLEANUP and CATCH
221 * -# \b variable \b initialization \n
222 * Variables which are used in the CLEANUP or CATCH clauses must
223 * be initialized before the point of the first possible THROW is
224 * reached. In the example above, CLEANUP would have trouble using cp3
225 * if mallocex() throws a exception when allocating a TOOBIG buffer.
226 * -# \b volatile \b variable \n
227 * Variables which are used in the CLEANUP or CATCH clauses MUST BE
228 * DECLARED AS "volatile", otherwise they might contain outdated
229 * information when an exception is thrown.
230 * -# \b clean \b before \b catch \n
231 * The CLEANUP clause is not only place before the CATCH clause in
232 * the source code, it also occures before in the control flow. So,
233 * resources being cleaned up cannot be used in the CATCH block. In the
234 * example, c3 gets freed before the printf placed in CATCH.
235 * -# \b variable \b uninitialization \n
236 * If resources are passed out of the scope of the
237 * TRY/CLEANUP/CATCH construct, they naturally shouldn't get
238 * cleaned up. The example above does free(3) cp1 in CLEANUP although
239 * its value was affected to globalcontext->first, invalidating this
242 * The following is fixed version of the code (annotated with the pitfall items
246 * \until end_of_good_example
251 /** @brief different kind of errors */
253 unknown_error = 0, /**< unknown error */
254 arg_error, /**< Invalid argument */
255 bound_error, /**< Out of bounds argument */
256 mismatch_error, /**< The provided ID does not match */
257 not_found_error, /**< The searched element was not found */
258 system_error, /**< a syscall did fail */
259 network_error, /**< error while sending/receiving data */
260 timeout_error, /**< not quick enough, dude */
261 cancel_error, /**< an action was canceled */
262 thread_error, /**< error while [un]locking */
263 host_error, /**< host failed */
264 tracing_error, /**< error during the simulation tracing */
265 io_error, /**< disk or file error */
266 vm_error /**< vm error */
269 XBT_PUBLIC(const char *) xbt_ex_catname(xbt_errcat_t cat);
271 /** @brief Structure describing an exception */
273 char *msg; /**< human readable message */
274 xbt_errcat_t category; /**< category like HTTP (what went wrong) */
275 int value; /**< like errno (why did it went wrong) */
277 char *procname; /**< Name of the process who thrown this */
278 int pid; /**< PID of the process who thrown this */
279 char *file; /**< Thrown point */
280 int line; /**< Thrown point */
281 char *func; /**< Thrown point */
284 char **bt_strings; /* only filed on display (or before the network propagation) */
285 void *bt[XBT_BACKTRACE_SIZE];
288 /* declare the running context type
289 * (that's where we get the process name for the logs and the exception storage)
290 * -- do not mess with it --
292 typedef struct xbt_running_ctx_t {
293 __ex_mctx_t *ctx_mctx; /* permanent machine context of enclosing try/catch */
294 int ctx_caught; /* temporary flag whether exception was caught */
295 volatile xbt_ex_t exception; /* temporary exception storage */
298 /* the static and dynamic initializers for a context structure */
299 #define XBT_RUNNING_CTX_INITIALIZER \
300 { NULL, 0, { /* content */ NULL, unknown_error, 0, \
301 /* throw point*/ NULL, 0, NULL, 0, NULL, \
302 /* backtrace */ 0, NULL, /* bt[] */ } }
304 XBT_PUBLIC_DATA(const xbt_running_ctx_t) __xbt_ex_ctx_initializer;
306 // #define XBT_RUNNING_CTX_INITIALIZE(ctx) (*(ctx) = __xbt_ex_ctx_initializer)
308 #define XBT_RUNNING_CTX_INITIALIZE(ctx) \
309 (ctx)->ctx_mctx = NULL; \
310 (ctx)->ctx_caught = 0; \
311 (ctx)->exception.msg = NULL; \
312 (ctx)->exception.category = unknown_error; \
313 (ctx)->exception.value = 0; \
314 (ctx)->exception.procname = NULL; \
315 (ctx)->exception.pid = 0; \
316 (ctx)->exception.file = NULL; \
317 (ctx)->exception.line = 0; \
318 (ctx)->exception.used = 0; \
319 (ctx)->exception.bt_strings = NULL;
321 /* the exception context */
322 typedef xbt_running_ctx_t *(*xbt_running_ctx_fetcher_t) (void);
323 XBT_PUBLIC_DATA(xbt_running_ctx_fetcher_t) __xbt_running_ctx_fetch;
324 XBT_PUBLIC( xbt_running_ctx_t *)__xbt_ex_ctx_default(void);
326 /* the termination handler */
327 typedef void (*ex_term_cb_t) (xbt_ex_t *);
328 XBT_PUBLIC_DATA(ex_term_cb_t) __xbt_ex_terminate;
329 XBT_PUBLIC( void )__xbt_ex_terminate_default(xbt_ex_t * e);
331 /** @brief Introduce a block where exception may be dealed with
336 xbt_running_ctx_t *__xbt_ex_ctx_ptr = __xbt_running_ctx_fetch(); \
337 int __ex_cleanup = 0; \
338 __ex_mctx_t __ex_mctx_me; \
339 __ex_mctx_t * __ex_mctx_en = __xbt_ex_ctx_ptr->ctx_mctx; \
340 __xbt_ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \
341 if (__ex_mctx_save(&__ex_mctx_me)) { \
344 /** @brief optional(!) block for cleanup
347 #define TRY_CLEANUP \
350 __xbt_ex_ctx_ptr->ctx_caught = 0; \
352 __ex_mctx_restored(&__ex_mctx_me); \
353 __xbt_ex_ctx_ptr->ctx_caught = 1; \
355 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
362 # define XBT_EX_T_CPLUSPLUSCAST (xbt_ex_t&)
364 # define XBT_EX_T_CPLUSPLUSCAST
368 /** @brief the block for catching (ie, deal with) an exception
372 DO_CATCH((e) = XBT_EX_T_CPLUSPLUSCAST __xbt_running_ctx_fetch()->exception)
374 /** @brief like CATCH(e) but without argument
377 * Useful if you only want to rethrow the exception caught, and do not want to
378 * bother with an unused variable.
380 #define CATCH_ANONYMOUS DO_CATCH(0)
382 #define DO_CATCH(_xbt_do_catch_set_e) \
385 if (!(__ex_cleanup)) \
386 __xbt_ex_ctx_ptr->ctx_caught = 0; \
388 if (!(__ex_cleanup)) { \
389 __ex_mctx_restored(&__ex_mctx_me); \
390 __xbt_ex_ctx_ptr->ctx_caught = 1; \
393 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
395 if ( !(__xbt_running_ctx_fetch()->ctx_caught) \
396 || ((void)(_xbt_do_catch_set_e), \
397 MAYDAY_CATCH(__xbt_running_ctx_fetch()->exception) 0)) { \
401 #define DO_THROW(running_ctx) \
402 do { /* deal with the exception */ \
403 xbt_running_ctx_t *ctx = (running_ctx); \
404 if (ctx->ctx_mctx == NULL) \
405 __xbt_ex_terminate((xbt_ex_t*)&(ctx->exception)); /* not catched */ \
407 __ex_mctx_restore(ctx->ctx_mctx); /* catched somewhere */ \
411 /** @brief Helper macro for THROW and THROWF
414 * @param _throw_ctx: the throwing context in which we should construct the exception
415 * @param c: category code (integer)
416 * @param v: value (integer)
417 * @param m: message text
419 * If called from within a TRY/CATCH construct, this exception
420 * is copied into the CATCH relevant variable program control flow
421 * is derouted to the CATCH (after the optional sg_cleanup).
423 * If no TRY/CATCH construct embeds this call, the program calls
426 * The THROW can be performed everywhere, including inside TRY,
427 * CLEANUP and CATCH blocks.
430 #define THROW_PREPARE(_throw_ctx, c, v, m) \
431 /* build the exception */ \
432 _throw_ctx->exception.msg = (m); \
433 _throw_ctx->exception.category = (xbt_errcat_t)(c); \
434 _throw_ctx->exception.value = (v); \
435 _throw_ctx->exception.procname = (char*)xbt_procname(); \
436 _throw_ctx->exception.pid = xbt_getpid(); \
437 _throw_ctx->exception.file = (char*)__FILE__; \
438 _throw_ctx->exception.line = __LINE__; \
439 _throw_ctx->exception.func = (char*)__func__; \
440 _throw_ctx->exception.bt_strings = NULL; \
441 xbt_backtrace_current((xbt_ex_t *)&(_throw_ctx->exception));
443 #define _XBT_THROW(c, v, m) \
444 do { /* change this sequence into one block */ \
445 xbt_running_ctx_t *_throw_ctx = __xbt_running_ctx_fetch(); \
446 THROW_PREPARE(_throw_ctx, c, v, m); \
447 DO_THROW(_throw_ctx); \
450 /** @brief Builds and throws an exception
452 #define THROW(c, v) _XBT_THROW(c, v, NULL)
454 /** @brief Builds and throws an exception with a printf-like formatted message
456 #define THROWF(c, v, ...) _XBT_THROW(c, v, bprintf(__VA_ARGS__))
458 #define THROW_IMPOSSIBLE \
459 THROWF(unknown_error, 0, "The Impossible Did Happen (yet again)")
460 #define THROW_UNIMPLEMENTED \
461 THROWF(unknown_error, 0, "Function %s unimplemented",__func__)
462 #define THROW_DEADCODE \
463 THROWF(unknown_error, 0, "Function %s was supposed to be DEADCODE, but it's not",__func__)
465 #define DIE_IMPOSSIBLE xbt_die("The Impossible Did Happen (yet again)")
467 /** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
470 #define RETHROW DO_THROW(__xbt_running_ctx_fetch())
472 /** @brief like THROWF, but adding some details to the message of an existing exception
475 #define RETHROWF(...) \
477 char *_xbt_ex_internal_msg = __xbt_running_ctx_fetch()->exception.msg; \
478 __xbt_running_ctx_fetch()->exception.msg = bprintf(__VA_ARGS__, \
479 _xbt_ex_internal_msg); \
480 free(_xbt_ex_internal_msg); \
484 /** @brief Exception destructor */
485 XBT_PUBLIC(void) xbt_ex_free(xbt_ex_t e);
486 /** @brief The display made by an exception that is not catched */
487 XBT_PUBLIC(void) xbt_ex_display(xbt_ex_t * e);
489 /** @brief Shows a backtrace of the current location */
490 XBT_PUBLIC(void) xbt_backtrace_display_current(void);
491 /** @brief reimplementation of glibc backtrace based directly on gcc library, without implicit malloc */
492 XBT_PUBLIC(int) xbt_backtrace_no_malloc(void**bt, int size);
493 /** @brief Captures a backtrace for further use */
494 XBT_PUBLIC(void) xbt_backtrace_current(xbt_ex_t * e);
495 /** @brief Display a previously captured backtrace */
496 XBT_PUBLIC(void) xbt_backtrace_display(xbt_ex_t * e);
497 /** @brief Get current backtrace with libunwind */
498 XBT_PUBLIC(int) xbt_libunwind_backtrace(void *bt[XBT_BACKTRACE_SIZE], int size);
503 #endif /* __XBT_EX_H__ */