3 /* ex - Exception Handling (modified to fit into SimGrid from OSSP version) */
5 /* Copyright (c) 2005-2006 Martin Quinson */
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 program is free software; you can redistribute it and/or modify it
12 * under the terms of the license (GNU LGPL) which comes with this package. */
17 #include "xbt/sysdep.h"
19 #include "xbt/virtu.h"
21 /*-*-* Emergency debuging: define this when the exceptions get crazy *-*-*/
28 # define MAYDAY_SAVE(m) printf("%d %s:%d save %p\n", \
29 (*xbt_getpid)(),__FILE__,__LINE__, \
32 # define MAYDAY_RESTORE(m) printf("%d %s:%d restore %p\n", \
33 (*xbt_getpid)(),__FILE__,__LINE__, \
36 # define MAYDAY_CATCH(e) printf("%d %s:%d Catched '%s'\n", \
37 (*xbt_getpid)(),__FILE__,__LINE__, \
41 # define MAYDAY_SAVE(m)
42 # define MAYDAY_RESTORE(m)
43 # define MAYDAY_CATCH(e)
46 /*-*-* end of debugging stuff *-*-*/
48 #if defined(__EX_MCTX_MCSC__)
49 #include <ucontext.h> /* POSIX.1 ucontext(3) */
50 #define __ex_mctx_struct ucontext_t uc;
51 #define __ex_mctx_save(mctx) (getcontext(&(mctx)->uc) == 0)
52 #define __ex_mctx_restored(mctx) /* noop */
53 #define __ex_mctx_restore(mctx) (void)setcontext(&(mctx)->uc)
55 #elif defined(__EX_MCTX_SSJLJ__)
56 #include <setjmp.h> /* POSIX.1 sigjmp_buf(3) */
57 #define __ex_mctx_struct sigjmp_buf jb;
58 #define __ex_mctx_save(mctx) (sigsetjmp((mctx)->jb, 1) == 0)
59 #define __ex_mctx_restored(mctx) /* noop */
60 #define __ex_mctx_restore(mctx) (void)siglongjmp((mctx)->jb, 1)
62 #elif defined(__EX_MCTX_SJLJ__) || !defined(__EX_MCTX_CUSTOM__) || defined(__EX_MAYDAY)
63 #include <setjmp.h> /* ISO-C jmp_buf(3) */
64 #define __ex_mctx_struct jmp_buf jb;
65 #define __ex_mctx_save(mctx) ( MAYDAY_SAVE(mctx) setjmp((mctx)->jb) == 0)
66 #define __ex_mctx_restored(mctx) /* noop */
67 #define __ex_mctx_restore(mctx) ( MAYDAY_RESTORE(mctx) (void)longjmp((mctx)->jb, 1))
70 /* declare the machine context type */
72 __ex_mctx_struct} __ex_mctx_t;
74 /** @addtogroup XBT_ex
75 * @brief A set of macros providing exception a la C++ in ANSI C (grounding feature)
77 * This module is a small ISO-C++ style exception handling library
78 * for use in the ISO-C language. It allows you to use the paradigm
79 * of throwing and catching exceptions in order to reduce the amount
80 * of error handling code without hindering program robustness.
82 * This is achieved by directly transferring exceptional return codes
83 * (and the program control flow) from the location where the exception
84 * is raised (throw point) to the location where it is handled (catch
85 * point) -- usually from a deeply nested sub-routine to a parent
86 * routine. All intermediate routines no longer have to make sure that
87 * the exceptional return codes from sub-routines are correctly passed
90 * These features are brought to you by a modified version of the libex
91 * library, one of the numerous masterpiece of Ralf S. Engelschall.
93 * \htmlonly <div class="toc">\endhtmlonly
95 * @section XBT_ex_toc TABLE OF CONTENTS
99 * - \ref XBT_ex_pitfalls
101 * \htmlonly </div> \endhtmlonly
103 * @section XBT_ex_intro DESCRIPTION
105 * In SimGrid, an exception is a triple <\a msg , \a category , \a value>
106 * where \a msg is a human-readable text describing the exceptional
107 * condition, \a code an integer describing what went wrong and \a value
108 * providing a sort of sub-category. (this is different in the original libex).
110 * @section XBT_ex_base BASIC USAGE
112 * \em TRY \b TRIED_BLOCK [\em CLEANUP \b CLEANUP_BLOCK] \em CATCH (variable) \b CATCH_BLOCK
114 * This is the primary syntactical construct provided. It is modeled after the
115 * ISO-C++ try-catch clause and should sound familiar to most of you.
117 * Any exception thrown directly from the TRIED_BLOCK block or from called
118 * subroutines is caught. Cleanups which must be done after this block
119 * (whenever an exception arised or not) should be placed into the optionnal
120 * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should
121 * be placed into the (mandatory) CATCH_BLOCK.
124 * In absence of exception, the control flow goes into the blocks TRIED_BLOCK
125 * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored.
127 * When an exception is thrown, the control flow goes through the following
128 * blocks: TRIED_BLOCK (up to the statement throwing the exception),
129 * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a
130 * variable for inspection inside the CATCH_BLOCK. This variable must be
131 * declared in the outter scope, but its value is only valid within the
135 * - TRY, CLEANUP and CATCH cannot be used separately, they work
136 * only in combination and form a language clause as a whole.
137 * - In contrast to the syntax of other languages (such as C++ or Jave) there
138 * is only one CATCH block and not multiple ones (all exceptions are
139 * of the same \em xbt_ex_t C type).
140 * - the variable of CATCH can naturally be reused in subsequent
142 * - it is possible to nest TRY clauses.
144 * The TRY block is a regular ISO-C language statement block, but
146 * <center><b>it is not
147 * allowed to jump into it via "goto" or longjmp(3) or out of it via "break",
148 * "return", "goto" or longjmp(3)</b>.</center>
150 * This is because there is some hidden setup and
151 * cleanup that needs to be done regardless of whether an exception is
152 * caught. Bypassing these steps will break the exception handling facility.
153 * The symptom are likely to be a segfault at the next exception raising point,
154 * ie far away from the point where you did the mistake. If you suspect
155 * that kind of error in your code, have a look at the little script
156 * <tt>tools/xbt_exception_checker</tt> in the CVS. It extracts all the TRY
157 * blocks from a set of C files you give it and display them (and only
158 * them) on the standard output. You can then grep for the forbidden
159 * keywords on that output.
161 * The CLEANUP and CATCH blocks are regular ISO-C language statement
162 * blocks without any restrictions. You are even allowed to throw (and, in the
163 * CATCH block, to re-throw) exceptions.
165 * There is one subtle detail you should remember about TRY blocks:
166 * Variables used in the CLEANUP or CATCH clauses must be declared with
167 * the storage class "volatile", otherwise they might contain outdated
168 * information if an exception is thrown.
171 * This is because you usually do not know which commands in the TRY
172 * were already successful before the exception was thrown (logically speaking)
173 * and because the underlying ISO-C setjmp(3) facility applies those
174 * restrictions (technically speaking). As a matter of fact, value changes
175 * between the TRY and the THROW may be discarded if you forget the
176 * "volatile" keyword.
178 * \section XBT_ex_pitfalls PROGRAMMING PITFALLS
180 * Exception handling is a very elegant and efficient way of dealing with
181 * exceptional situation. Nevertheless it requires additional discipline in
182 * programming and there are a few pitfalls one must be aware of. Look the
183 * following code which shows some pitfalls and contains many errors (assuming
184 * a mallocex() function which throws an exception if malloc(3) fails):
188 * \until end_of_bad_example
190 * This example raises a few issues:
191 * -# \b variable \b scope \n
192 * Variables which are used in the CLEANUP or CATCH clauses must be
193 * declared before the TRY clause, otherwise they only exist inside the
194 * TRY block. In the example above, cp1, cp2 and cp3 only exist in the
195 * TRY block and are invisible from the CLEANUP and CATCH
197 * -# \b variable \b initialization \n
198 * Variables which are used in the CLEANUP or CATCH clauses must
199 * be initialized before the point of the first possible THROW is
200 * reached. In the example above, CLEANUP would have trouble using cp3
201 * if mallocex() throws a exception when allocating a TOOBIG buffer.
202 * -# \b volatile \b variable \n
203 * Variables which are used in the CLEANUP or CATCH clauses MUST BE
204 * DECLARED AS "volatile", otherwise they might contain outdated
205 * information when an exception is thrown.
206 * -# \b clean \b before \b catch \n
207 * The CLEANUP clause is not only place before the CATCH clause in
208 * the source code, it also occures before in the control flow. So,
209 * resources being cleaned up cannot be used in the CATCH block. In the
210 * example, c3 gets freed before the printf placed in CATCH.
211 * -# \b variable \b uninitialization \n
212 * If resources are passed out of the scope of the
213 * TRY/CLEANUP/CATCH construct, they naturally shouldn't get
214 * cleaned up. The example above does free(3) cp1 in CLEANUP although
215 * its value was affected to globalcontext->first, invalidating this
218 * The following is fixed version of the code (annotated with the pitfall items
222 * \until end_of_good_example
227 /** @brief different kind of errors */
229 unknown_error = 0,/**< unknown error */
230 arg_error, /**< Invalid argument */
231 bound_error, /**< Out of bounds argument */
232 mismatch_error, /**< The provided ID does not match */
233 not_found_error, /**< The searched element was not found */
235 system_error, /**< a syscall did fail */
236 network_error, /**< error while sending/receiving data */
237 timeout_error, /**< not quick enough, dude */
238 thread_error, /**< error while [un]locking */
239 host_error /**< host failed */
242 XBT_PUBLIC(const char *) xbt_ex_catname(xbt_errcat_t cat);
244 /** @brief Structure describing an exception */
246 char *msg; /**< human readable message */
247 xbt_errcat_t category;
248 /**< category like HTTP (what went wrong) */
249 int value; /**< like errno (why did it went wrong) */
252 /**< whether it was raised remotely */
253 char *host;/**< NULL locally thrown exceptions; full hostname if remote ones */
254 /* FIXME: host should be hostname:port[#thread] */
256 /**< Name of the process who thrown this */
257 int pid; /**< PID of the process who thrown this */
258 char *file;/**< Thrown point */
259 int line; /**< Thrown point */
260 char *func;/**< Thrown point */
263 char **bt_strings; /* only filed on display (or before the network propagation) */
264 void *bt[XBT_BACKTRACE_SIZE];
267 /* declare the context type (private) */
269 __ex_mctx_t *ctx_mctx; /* permanent machine context of enclosing try/catch */
270 volatile int ctx_caught; /* temporary flag whether exception was caught */
271 volatile xbt_ex_t ctx_ex; /* temporary exception storage */
274 /* the static and dynamic initializers for a context structure */
275 #define XBT_CTX_INITIALIZER \
276 { NULL, 0, { /* content */ NULL, unknown_error, 0, \
277 /* throw point*/ 0,NULL, NULL,0, NULL, 0, NULL,\
278 /* backtrace */ 0,NULL,{NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL} } }
279 #define XBT_CTX_INITIALIZE(ctx) \
281 (ctx)->ctx_mctx = NULL; \
282 (ctx)->ctx_caught = 0; \
283 (ctx)->ctx_ex.msg = NULL; \
284 (ctx)->ctx_ex.category = 0; \
285 (ctx)->ctx_ex.value = 0; \
286 (ctx)->ctx_ex.remote = 0; \
287 (ctx)->ctx_ex.host = NULL; \
288 (ctx)->ctx_ex.procname = NULL; \
289 (ctx)->ctx_ex.pid = 0; \
290 (ctx)->ctx_ex.file = NULL; \
291 (ctx)->ctx_ex.line = 0; \
292 (ctx)->ctx_ex.func = NULL; \
293 (ctx)->ctx_ex.bt[0] = NULL; \
294 (ctx)->ctx_ex.bt[1] = NULL; \
295 (ctx)->ctx_ex.bt[2] = NULL; \
296 (ctx)->ctx_ex.bt[3] = NULL; \
297 (ctx)->ctx_ex.bt[4] = NULL; \
298 (ctx)->ctx_ex.bt[5] = NULL; \
299 (ctx)->ctx_ex.bt[6] = NULL; \
300 (ctx)->ctx_ex.bt[7] = NULL; \
301 (ctx)->ctx_ex.bt[8] = NULL; \
302 (ctx)->ctx_ex.bt[9] = NULL; \
303 (ctx)->ctx_ex.used = 0; \
304 (ctx)->ctx_ex.bt_strings = NULL; \
307 /* the exception context */
308 typedef ex_ctx_t *(*ex_ctx_cb_t) (void);
309 XBT_PUBLIC_DATA(ex_ctx_cb_t) __xbt_ex_ctx;
310 extern ex_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 extern void __xbt_ex_terminate_default(xbt_ex_t * e);
317 /** @brief Introduce a block where exception may be dealed with
322 ex_ctx_t *__xbt_ex_ctx_ptr = __xbt_ex_ctx(); \
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
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
361 if (!(__ex_cleanup)) \
362 __xbt_ex_ctx_ptr->ctx_caught = 0; \
364 if (!(__ex_cleanup)) { \
365 __ex_mctx_restored(&__ex_mctx_me); \
366 __xbt_ex_ctx_ptr->ctx_caught = 1; \
369 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
371 if ( !(__xbt_ex_ctx()->ctx_caught) \
372 || ((e) = XBT_EX_T_CPLUSPLUSCAST __xbt_ex_ctx()->ctx_ex, MAYDAY_CATCH(e) 0)) { \
376 #define DO_THROW(e) \
377 /* deal with the exception */ \
378 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
379 __xbt_ex_terminate((xbt_ex_t *)&(e)); /* not catched */\
381 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); /* catched somewhere */ \
382 abort() /* nope, stupid GCC, we won't survive a THROW (this won't be reached) */
384 /** @brief Helper macro for THROWS0-6
387 * @param c: category code (integer)
388 * @param v: value (integer)
389 * @param m: message text
391 * If called from within a TRY/CATCH construct, this exception
392 * is copied into the CATCH relevant variable program control flow
393 * is derouted to the CATCH (after the optional sg_cleanup).
395 * If no TRY/CATCH construct embeeds this call, the program calls
398 * The THROW can be performed everywhere, including inside TRY,
399 * CLEANUP and CATCH blocks.
402 #define _THROW(c,v,m) \
403 do { /* change this sequence into one block */ \
404 ex_ctx_t *_throw_ctx = __xbt_ex_ctx(); \
405 /* build the exception */ \
406 _throw_ctx->ctx_ex.msg = (m); \
407 _throw_ctx->ctx_ex.category = (xbt_errcat_t)(c); \
408 _throw_ctx->ctx_ex.value = (v); \
409 _throw_ctx->ctx_ex.remote = 0; \
410 _throw_ctx->ctx_ex.host = (char*)NULL; \
411 _throw_ctx->ctx_ex.procname = (char*)xbt_procname(); \
412 _throw_ctx->ctx_ex.pid = (*xbt_getpid)(); \
413 _throw_ctx->ctx_ex.file = (char*)__FILE__; \
414 _throw_ctx->ctx_ex.line = __LINE__; \
415 _throw_ctx->ctx_ex.func = (char*)_XBT_FUNCTION; \
416 _throw_ctx->ctx_ex.bt_strings = NULL; \
417 xbt_backtrace_current( (xbt_ex_t *) &(_throw_ctx->ctx_ex) ); \
418 DO_THROW(_throw_ctx->ctx_ex); \
420 /* __xbt_ex_ctx()->ctx_ex.used = backtrace((void**)__xbt_ex_ctx()->ctx_ex.bt,XBT_BACKTRACE_SIZE); */
422 /** @brief Builds and throws an exception with a string taking no arguments
424 #define THROW0(c,v,m) _THROW(c,v,(m?bprintf(m):NULL))
425 /** @brief Builds and throws an exception with a string taking one argument
427 #define THROW1(c,v,m,a1) _THROW(c,v,bprintf(m,a1))
428 /** @brief Builds and throws an exception with a string taking two arguments
430 #define THROW2(c,v,m,a1,a2) _THROW(c,v,bprintf(m,a1,a2))
431 /** @brief Builds and throws an exception with a string taking three arguments
433 #define THROW3(c,v,m,a1,a2,a3) _THROW(c,v,bprintf(m,a1,a2,a3))
434 /** @brief Builds and throws an exception with a string taking four arguments
436 #define THROW4(c,v,m,a1,a2,a3,a4) _THROW(c,v,bprintf(m,a1,a2,a3,a4))
437 /** @brief Builds and throws an exception with a string taking five arguments
439 #define THROW5(c,v,m,a1,a2,a3,a4,a5) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5))
440 /** @brief Builds and throws an exception with a string taking six arguments
442 #define THROW6(c,v,m,a1,a2,a3,a4,a5,a6) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6))
443 /** @brief Builds and throws an exception with a string taking seven arguments
445 #define THROW7(c,v,m,a1,a2,a3,a4,a5,a6,a7) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6,a7))
447 #define THROW_IMPOSSIBLE THROW0(unknown_error,0,"The Impossible Did Happen (yet again)")
448 #define THROW_UNIMPLEMENTED THROW1(unknown_error,0,"Function %s unimplemented",_XBT_FUNCTION)
451 # define DIE_IMPOSSIBLE xbt_assert0(0,"The Impossible Did Happen (yet again)")
453 # define DIE_IMPOSSIBLE exit(1);
456 /** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
461 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
462 __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); \
464 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); \
470 #define _XBT_PRE_RETHROW \
472 char *_xbt_ex_internal_msg = __xbt_ex_ctx()->ctx_ex.msg; \
473 __xbt_ex_ctx()->ctx_ex.msg = bprintf(
474 #define _XBT_POST_RETHROW \
475 _xbt_ex_internal_msg); \
476 free(_xbt_ex_internal_msg); \
481 /** @brief like THROW0, but adding some details to the message of an existing exception
484 #define RETHROW0(msg) _XBT_PRE_RETHROW msg, _XBT_POST_RETHROW
485 /** @brief like THROW1, but adding some details to the message of an existing exception
488 #define RETHROW1(msg,a) _XBT_PRE_RETHROW msg,a, _XBT_POST_RETHROW
489 /** @brief like THROW2, but adding some details to the message of an existing exception
492 #define RETHROW2(msg,a,b) _XBT_PRE_RETHROW msg,a,b, _XBT_POST_RETHROW
493 /** @brief like THROW3, but adding some details to the message of an existing exception
496 #define RETHROW3(msg,a,b,c) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
497 /** @brief like THROW4, but adding some details to the message of an existing exception
500 #define RETHROW4(msg,a,b,c,d) _XBT_PRE_RETHROW msg,a,b,c,d, _XBT_POST_RETHROW
501 /** @brief like THROW5, but adding some details to the message of an existing exception
504 #define RETHROW5(msg,a,b,c,d,e) _XBT_PRE_RETHROW msg,a,b,c,d,e, _XBT_POST_RETHROW
506 /** @brief Exception destructor */
507 XBT_PUBLIC(void) xbt_ex_free(xbt_ex_t e);
509 /** @brief Shows a backtrace of the current location */
510 XBT_PUBLIC(void) xbt_backtrace_display_current(void);
511 /** @brief Captures a backtrace for further use */
512 XBT_PUBLIC(void) xbt_backtrace_current(xbt_ex_t * e);
513 /** @brief Display a previously captured backtrace */
514 XBT_PUBLIC(void) xbt_backtrace_display(xbt_ex_t * e);
517 #endif /* __XBT_EX_H__ */