1 /* ex - Exception Handling */
3 /* Copyright (c) 2005-2013. The SimGrid Team. */
4 /* Copyright (c) 2002-2004 Ralf S. Engelschall <rse@engelschall.com> */
5 /* Copyright (c) 2002-2004 The OSSP Project <http://www.ossp.org/> */
6 /* Copyright (c) 2002-2004 Cable & Wireless <http://www.cw.com/> */
7 /* All rights reserved. */
9 /* This code is inspirated from the OSSP version (as retrieved back in 2004)*/
10 /* It was heavily modified to fit the SimGrid framework. */
12 /* The OSSP version has the following copyright notice:
13 ** OSSP ex - Exception Handling
14 ** Copyright (c) 2002-2004 Ralf S. Engelschall <rse@engelschall.com>
15 ** Copyright (c) 2002-2004 The OSSP Project <http://www.ossp.org/>
16 ** Copyright (c) 2002-2004 Cable & Wireless <http://www.cw.com/>
18 ** This file is part of OSSP ex, an exception handling library
19 ** which can be found at http://www.ossp.org/pkg/lib/ex/.
21 ** Permission to use, copy, modify, and distribute this software for
22 ** any purpose with or without fee is hereby granted, provided that
23 ** the above copyright notice and this permission notice appear in all
26 ** THIS SOFTWARE IS PROVIDED `AS IS'' AND ANY EXPRESSED OR IMPLIED
27 ** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
28 ** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 ** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
30 ** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
31 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
32 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
33 ** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
34 ** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
35 ** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
36 ** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 /* The extensions made for the SimGrid project can either be distributed */
41 /* under the same license, or under the LGPL v2.1 */
46 #include "xbt/sysdep.h"
48 #include "xbt/virtu.h"
52 /*-*-* Emergency debuging: define this when the exceptions get crazy *-*-*/
57 # define MAYDAY_SAVE(m) printf("%d %s:%d save %p\n", \
58 xbt_getpid(), __FILE__, __LINE__, \
61 # define MAYDAY_RESTORE(m) printf("%d %s:%d restore %p\n", \
62 xbt_getpid(), __FILE__, __LINE__, \
65 # define MAYDAY_CATCH(e) printf("%d %s:%d Catched '%s'\n", \
66 xbt_getpid(), __FILE__, __LINE__, \
70 # define MAYDAY_SAVE(m)
71 # define MAYDAY_RESTORE(m)
72 # define MAYDAY_CATCH(e)
74 /*-*-* end of debugging stuff *-*-*/
75 #if defined(__EX_MCTX_MCSC__)
76 #include <ucontext.h> /* POSIX.1 ucontext(3) */
77 #define __ex_mctx_struct ucontext_t uc;
78 #define __ex_mctx_save(mctx) (getcontext(&(mctx)->uc) == 0)
79 #define __ex_mctx_restored(mctx) /* noop */
80 #define __ex_mctx_restore(mctx) (void)setcontext(&(mctx)->uc)
81 #elif defined(__EX_MCTX_SSJLJ__)
82 #include <setjmp.h> /* POSIX.1 sigjmp_buf(3) */
83 #define __ex_mctx_struct sigjmp_buf jb;
84 #define __ex_mctx_save(mctx) (sigsetjmp((mctx)->jb, 1) == 0)
85 #define __ex_mctx_restored(mctx) /* noop */
86 #define __ex_mctx_restore(mctx) (void)siglongjmp((mctx)->jb, 1)
87 #elif defined(__EX_MCTX_SJLJ__) || !defined(__EX_MCTX_CUSTOM__) || defined(__EX_MAYDAY)
88 #include <setjmp.h> /* ISO-C jmp_buf(3) */
89 #define __ex_mctx_struct jmp_buf jb;
90 #define __ex_mctx_save(mctx) ( MAYDAY_SAVE(mctx) setjmp((mctx)->jb) == 0)
91 #define __ex_mctx_restored(mctx) /* noop */
92 #define __ex_mctx_restore(mctx) ( MAYDAY_RESTORE(mctx) (void)longjmp((mctx)->jb, 1))
94 /* declare the machine context type */
96 __ex_mctx_struct} __ex_mctx_t;
98 /** @addtogroup XBT_ex
99 * @brief A set of macros providing exception a la C++ in ANSI C (grounding feature)
101 * This module is a small ISO-C++ style exception handling library
102 * for use in the ISO-C language. It allows you to use the paradigm
103 * of throwing and catching exceptions in order to reduce the amount
104 * of error handling code without hindering program robustness.
106 * This is achieved by directly transferring exceptional return codes
107 * (and the program control flow) from the location where the exception
108 * is raised (throw point) to the location where it is handled (catch
109 * point) -- usually from a deeply nested sub-routine to a parent
110 * routine. All intermediate routines no longer have to make sure that
111 * the exceptional return codes from sub-routines are correctly passed
112 * back to the parent.
114 * These features are brought to you by a modified version of the libex
115 * library, one of the numerous masterpiece of Ralf S. Engelschall.
117 * \htmlonly <div class="toc">\endhtmlonly
119 * @section XBT_ex_toc TABLE OF CONTENTS
121 * - \ref XBT_ex_intro
123 * - \ref XBT_ex_pitfalls
125 * \htmlonly </div> \endhtmlonly
127 * @section XBT_ex_intro DESCRIPTION
129 * In SimGrid, an exception is a triple <\a msg , \a category , \a value>
130 * where \a msg is a human-readable text describing the exceptional
131 * condition, \a code an integer describing what went wrong and \a value
132 * providing a sort of sub-category. (this is different in the original libex).
134 * @section XBT_ex_base BASIC USAGE
136 * \em TRY \b TRIED_BLOCK [\em TRY_CLEANUP \b CLEANUP_BLOCK] \em CATCH (variable) \b CATCH_BLOCK
138 * This is the primary syntactical construct provided. It is modeled after the
139 * ISO-C++ try-catch clause and should sound familiar to most of you.
141 * Any exception thrown directly from the TRIED_BLOCK block or from called
142 * subroutines is caught. Cleanups which must be done after this block
143 * (whenever an exception arose or not) should be placed into the optionnal
144 * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should
145 * be placed into the (mandatory) CATCH_BLOCK.
148 * In absence of exception, the control flow goes into the blocks TRIED_BLOCK
149 * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored.
151 * When an exception is thrown, the control flow goes through the following
152 * blocks: TRIED_BLOCK (up to the statement throwing the exception),
153 * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a
154 * variable for inspection inside the CATCH_BLOCK. This variable must be
155 * declared in the outter scope, but its value is only valid within the
159 * - TRY, CLEANUP and CATCH cannot be used separately, they work
160 * only in combination and form a language clause as a whole.
161 * - In contrast to the syntax of other languages (such as C++ or Jave) there
162 * is only one CATCH block and not multiple ones (all exceptions are
163 * of the same \em xbt_ex_t C type).
164 * - the variable of CATCH can naturally be reused in subsequent
166 * - it is possible to nest TRY clauses.
168 * The TRY block is a regular ISO-C language statement block, but
170 * <center><b>it is not
171 * allowed to jump into it via "goto" or longjmp(3) or out of it via "break",
172 * "return", "goto" or longjmp(3)</b>.</center>
174 * This is because there is some hidden setup and
175 * cleanup that needs to be done regardless of whether an exception is
176 * caught. Bypassing these steps will break the exception handling facility.
177 * The symptom are likely to be a segfault at the next exception raising point,
178 * ie far away from the point where you did the mistake. If you suspect
179 * that kind of error in your code, have a look at the little script
180 * <tt>tools/xbt_exception_checker</tt> in the CVS. It extracts all the TRY
181 * blocks from a set of C files you give it and display them (and only
182 * them) on the standard output. You can then grep for the forbidden
183 * keywords on that output.
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 --
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;
305 #define XBT_RUNNING_CTX_INITIALIZE(ctx) (*(ctx) = __xbt_ex_ctx_initializer)
307 /* the exception context */
308 typedef xbt_running_ctx_t *(*xbt_running_ctx_fetcher_t) (void);
309 XBT_PUBLIC_DATA(xbt_running_ctx_fetcher_t) __xbt_running_ctx_fetch;
310 XBT_PUBLIC( xbt_running_ctx_t *)__xbt_ex_ctx_default(void);
312 /* the termination handler */
313 typedef void (*ex_term_cb_t) (xbt_ex_t *);
314 XBT_PUBLIC_DATA(ex_term_cb_t) __xbt_ex_terminate;
315 XBT_PUBLIC( void )__xbt_ex_terminate_default(xbt_ex_t * e);
317 /** @brief Introduce a block where exception may be dealed with
322 xbt_running_ctx_t *__xbt_ex_ctx_ptr = __xbt_running_ctx_fetch(); \
323 int __ex_cleanup = 0; \
324 __ex_mctx_t *__ex_mctx_en; \
325 __ex_mctx_t __ex_mctx_me; \
326 __ex_mctx_en = __xbt_ex_ctx_ptr->ctx_mctx; \
327 __xbt_ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \
328 if (__ex_mctx_save(&__ex_mctx_me)) { \
331 /** @brief optional(!) block for cleanup
334 #define TRY_CLEANUP \
337 __xbt_ex_ctx_ptr->ctx_caught = 0; \
339 __ex_mctx_restored(&__ex_mctx_me); \
340 __xbt_ex_ctx_ptr->ctx_caught = 1; \
342 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
349 # define XBT_EX_T_CPLUSPLUSCAST (xbt_ex_t&)
351 # define XBT_EX_T_CPLUSPLUSCAST
355 /** @brief the block for catching (ie, deal with) an exception
359 DO_CATCH((e) = XBT_EX_T_CPLUSPLUSCAST __xbt_running_ctx_fetch()->exception)
361 /** @brief like CATCH(e) but without argument
364 * Useful if you only want to rethrow the exception caught, and do not want to
365 * bother with an unused variable.
367 #define CATCH_ANONYMOUS DO_CATCH(0)
369 #define DO_CATCH(_xbt_do_catch_set_e) \
372 if (!(__ex_cleanup)) \
373 __xbt_ex_ctx_ptr->ctx_caught = 0; \
375 if (!(__ex_cleanup)) { \
376 __ex_mctx_restored(&__ex_mctx_me); \
377 __xbt_ex_ctx_ptr->ctx_caught = 1; \
380 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
382 if ( !(__xbt_running_ctx_fetch()->ctx_caught) \
383 || ((void)(_xbt_do_catch_set_e), \
384 MAYDAY_CATCH(__xbt_running_ctx_fetch()->exception) 0)) { \
388 #define DO_THROW(running_ctx) \
389 do { /* deal with the exception */ \
390 xbt_running_ctx_t *ctx = (running_ctx); \
391 if (ctx->ctx_mctx == NULL) \
392 __xbt_ex_terminate((xbt_ex_t*)&(ctx->exception)); /* not catched */ \
394 __ex_mctx_restore(ctx->ctx_mctx); /* catched somewhere */ \
395 abort(); /* nope, stupid GCC, we won't survive a THROW */ \
396 /* (this won't be reached) */ \
399 /** @brief Helper macro for THROW and THROWF
402 * @param _throw_ctx: the throwing context in which we should construct the exception
403 * @param c: category code (integer)
404 * @param v: value (integer)
405 * @param m: message text
407 * If called from within a TRY/CATCH construct, this exception
408 * is copied into the CATCH relevant variable program control flow
409 * is derouted to the CATCH (after the optional sg_cleanup).
411 * If no TRY/CATCH construct embeds this call, the program calls
414 * The THROW can be performed everywhere, including inside TRY,
415 * CLEANUP and CATCH blocks.
418 #define THROW_PREPARE(_throw_ctx, c, v, m) \
419 /* build the exception */ \
420 _throw_ctx->exception.msg = (m); \
421 _throw_ctx->exception.category = (xbt_errcat_t)(c); \
422 _throw_ctx->exception.value = (v); \
423 _throw_ctx->exception.procname = (char*)xbt_procname(); \
424 _throw_ctx->exception.pid = xbt_getpid(); \
425 _throw_ctx->exception.file = (char*)__FILE__; \
426 _throw_ctx->exception.line = __LINE__; \
427 _throw_ctx->exception.func = (char*)_XBT_FUNCTION; \
428 _throw_ctx->exception.bt_strings = NULL; \
429 xbt_backtrace_current((xbt_ex_t *)&(_throw_ctx->exception));
431 #define _THROW(c, v, m) \
432 do { /* change this sequence into one block */ \
433 xbt_running_ctx_t *_throw_ctx = __xbt_running_ctx_fetch(); \
434 THROW_PREPARE(_throw_ctx, c, v, m); \
435 DO_THROW(_throw_ctx); \
438 /** @brief Builds and throws an exception
440 #define THROW(c, v) _THROW(c, v, NULL)
442 /** @brief Builds and throws an exception with a printf-like formatted message
444 #define THROWF(c, v, ...) _THROW(c, v, bprintf(__VA_ARGS__))
446 #define THROW_IMPOSSIBLE \
447 THROWF(unknown_error, 0, "The Impossible Did Happen (yet again)")
448 #define THROW_UNIMPLEMENTED \
449 THROWF(unknown_error, 0, "Function %s unimplemented",_XBT_FUNCTION)
451 #define DIE_IMPOSSIBLE xbt_die("The Impossible Did Happen (yet again)")
453 /** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
456 #define RETHROW DO_THROW(__xbt_running_ctx_fetch())
458 /** @brief like THROWF, but adding some details to the message of an existing exception
461 #define RETHROWF(...) \
463 char *_xbt_ex_internal_msg = __xbt_running_ctx_fetch()->exception.msg; \
464 __xbt_running_ctx_fetch()->exception.msg = bprintf(__VA_ARGS__, \
465 _xbt_ex_internal_msg); \
466 free(_xbt_ex_internal_msg); \
470 /** @brief Exception destructor */
471 XBT_PUBLIC(void) xbt_ex_free(xbt_ex_t e);
473 /** @brief Shows a backtrace of the current location */
474 XBT_PUBLIC(void) xbt_backtrace_display_current(void);
475 /** @brief reimplementation of glibc backtrace based directly on gcc library, without implicit malloc */
476 XBT_PUBLIC(int) xbt_backtrace_no_malloc(void**bt, int size);
477 /** @brief Captures a backtrace for further use */
478 XBT_PUBLIC(void) xbt_backtrace_current(xbt_ex_t * e);
479 /** @brief Display a previously captured backtrace */
480 XBT_PUBLIC(void) xbt_backtrace_display(xbt_ex_t * e);
481 /** @brief Get current backtrace with libunwind */
482 XBT_PUBLIC(int) xbt_libunwind_backtrace(void *bt[XBT_BACKTRACE_SIZE], int size);
484 #ifdef XBT_USE_DEPRECATED
486 /* Kept for backward compatibility. */
488 #define THROW0(c, v, m) \
489 do { if (m) THROWF(c, v, m); else THROW(c, v); } while (0)
490 #define THROW1(c, v, ...) THROWF(c, v, __VA_ARGS__)
491 #define THROW2(c, v, ...) THROWF(c, v, __VA_ARGS__)
492 #define THROW3(c, v, ...) THROWF(c, v, __VA_ARGS__)
493 #define THROW4(c, v, ...) THROWF(c, v, __VA_ARGS__)
494 #define THROW5(c, v, ...) THROWF(c, v, __VA_ARGS__)
495 #define THROW6(c, v, ...) THROWF(c, v, __VA_ARGS__)
496 #define THROW7(c, v, ...) THROWF(c, v, __VA_ARGS__)
498 #define RETHROW0(...) RETHROWF(__VA_ARGS__)
499 #define RETHROW1(...) RETHROWF(__VA_ARGS__)
500 #define RETHROW2(...) RETHROWF(__VA_ARGS__)
501 #define RETHROW3(...) RETHROWF(__VA_ARGS__)
502 #define RETHROW4(...) RETHROWF(__VA_ARGS__)
503 #define RETHROW5(...) RETHROWF(__VA_ARGS__)
510 #endif /* __XBT_EX_H__ */