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"
23 /*-*-* Emergency debuging: define this when the exceptions get crazy *-*-*/
30 # define MAYDAY_SAVE(m) printf("%d %s:%d save %p\n", \
31 (*xbt_getpid)(),__FILE__,__LINE__, \
34 # define MAYDAY_RESTORE(m) printf("%d %s:%d restore %p\n", \
35 (*xbt_getpid)(),__FILE__,__LINE__, \
38 # define MAYDAY_CATCH(e) printf("%d %s:%d Catched '%s'\n", \
39 (*xbt_getpid)(),__FILE__,__LINE__, \
43 # define MAYDAY_SAVE(m)
44 # define MAYDAY_RESTORE(m)
45 # define MAYDAY_CATCH(e)
48 /*-*-* end of debugging stuff *-*-*/
50 #if defined(__EX_MCTX_MCSC__)
51 #include <ucontext.h> /* POSIX.1 ucontext(3) */
52 #define __ex_mctx_struct ucontext_t uc;
53 #define __ex_mctx_save(mctx) (getcontext(&(mctx)->uc) == 0)
54 #define __ex_mctx_restored(mctx) /* noop */
55 #define __ex_mctx_restore(mctx) (void)setcontext(&(mctx)->uc)
57 #elif defined(__EX_MCTX_SSJLJ__)
58 #include <setjmp.h> /* POSIX.1 sigjmp_buf(3) */
59 #define __ex_mctx_struct sigjmp_buf jb;
60 #define __ex_mctx_save(mctx) (sigsetjmp((mctx)->jb, 1) == 0)
61 #define __ex_mctx_restored(mctx) /* noop */
62 #define __ex_mctx_restore(mctx) (void)siglongjmp((mctx)->jb, 1)
64 #elif defined(__EX_MCTX_SJLJ__) || !defined(__EX_MCTX_CUSTOM__) || defined(__EX_MAYDAY)
65 #include <setjmp.h> /* ISO-C jmp_buf(3) */
66 #define __ex_mctx_struct jmp_buf jb;
67 #define __ex_mctx_save(mctx) ( MAYDAY_SAVE(mctx) setjmp((mctx)->jb) == 0)
68 #define __ex_mctx_restored(mctx) /* noop */
69 #define __ex_mctx_restore(mctx) ( MAYDAY_RESTORE(mctx) (void)longjmp((mctx)->jb, 1))
72 /* declare the machine context type */
74 __ex_mctx_struct} __ex_mctx_t;
76 /** @addtogroup XBT_ex
77 * @brief A set of macros providing exception a la C++ in ANSI C (grounding feature)
79 * This module is a small ISO-C++ style exception handling library
80 * for use in the ISO-C language. It allows you to use the paradigm
81 * of throwing and catching exceptions in order to reduce the amount
82 * of error handling code without hindering program robustness.
84 * This is achieved by directly transferring exceptional return codes
85 * (and the program control flow) from the location where the exception
86 * is raised (throw point) to the location where it is handled (catch
87 * point) -- usually from a deeply nested sub-routine to a parent
88 * routine. All intermediate routines no longer have to make sure that
89 * the exceptional return codes from sub-routines are correctly passed
92 * These features are brought to you by a modified version of the libex
93 * library, one of the numerous masterpiece of Ralf S. Engelschall.
95 * \htmlonly <div class="toc">\endhtmlonly
97 * @section XBT_ex_toc TABLE OF CONTENTS
101 * - \ref XBT_ex_pitfalls
103 * \htmlonly </div> \endhtmlonly
105 * @section XBT_ex_intro DESCRIPTION
107 * In SimGrid, an exception is a triple <\a msg , \a category , \a value>
108 * where \a msg is a human-readable text describing the exceptional
109 * condition, \a code an integer describing what went wrong and \a value
110 * providing a sort of sub-category. (this is different in the original libex).
112 * @section XBT_ex_base BASIC USAGE
114 * \em TRY \b TRIED_BLOCK [\em CLEANUP \b CLEANUP_BLOCK] \em CATCH (variable) \b CATCH_BLOCK
116 * This is the primary syntactical construct provided. It is modeled after the
117 * ISO-C++ try-catch clause and should sound familiar to most of you.
119 * Any exception thrown directly from the TRIED_BLOCK block or from called
120 * subroutines is caught. Cleanups which must be done after this block
121 * (whenever an exception arised or not) should be placed into the optionnal
122 * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should
123 * be placed into the (mandatory) CATCH_BLOCK.
126 * In absence of exception, the control flow goes into the blocks TRIED_BLOCK
127 * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored.
129 * When an exception is thrown, the control flow goes through the following
130 * blocks: TRIED_BLOCK (up to the statement throwing the exception),
131 * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a
132 * variable for inspection inside the CATCH_BLOCK. This variable must be
133 * declared in the outter scope, but its value is only valid within the
137 * - TRY, CLEANUP and CATCH cannot be used separately, they work
138 * only in combination and form a language clause as a whole.
139 * - In contrast to the syntax of other languages (such as C++ or Jave) there
140 * is only one CATCH block and not multiple ones (all exceptions are
141 * of the same \em xbt_ex_t C type).
142 * - the variable of CATCH can naturally be reused in subsequent
144 * - it is possible to nest TRY clauses.
146 * The TRY block is a regular ISO-C language statement block, but
148 * <center><b>it is not
149 * allowed to jump into it via "goto" or longjmp(3) or out of it via "break",
150 * "return", "goto" or longjmp(3)</b>.</center>
152 * This is because there is some hidden setup and
153 * cleanup that needs to be done regardless of whether an exception is
154 * caught. Bypassing these steps will break the exception handling facility.
155 * The symptom are likely to be a segfault at the next exception raising point,
156 * ie far away from the point where you did the mistake. If you suspect
157 * that kind of error in your code, have a look at the little script
158 * <tt>tools/xbt_exception_checker</tt> in the CVS. It extracts all the TRY
159 * blocks from a set of C files you give it and display them (and only
160 * them) on the standard output. You can then grep for the forbidden
161 * keywords on that output.
163 * The CLEANUP and CATCH blocks are regular ISO-C language statement
164 * blocks without any restrictions. You are even allowed to throw (and, in the
165 * CATCH block, to re-throw) exceptions.
167 * There is one subtle detail you should remember about TRY blocks:
168 * Variables used in the CLEANUP or CATCH clauses must be declared with
169 * the storage class "volatile", otherwise they might contain outdated
170 * information if an exception is thrown.
173 * This is because you usually do not know which commands in the TRY
174 * were already successful before the exception was thrown (logically speaking)
175 * and because the underlying ISO-C setjmp(3) facility applies those
176 * restrictions (technically speaking). As a matter of fact, value changes
177 * between the TRY and the THROW may be discarded if you forget the
178 * "volatile" keyword.
180 * \section XBT_ex_pitfalls PROGRAMMING PITFALLS
182 * Exception handling is a very elegant and efficient way of dealing with
183 * exceptional situation. Nevertheless it requires additional discipline in
184 * programming and there are a few pitfalls one must be aware of. Look the
185 * following code which shows some pitfalls and contains many errors (assuming
186 * a mallocex() function which throws an exception if malloc(3) fails):
190 * \until end_of_bad_example
192 * This example raises a few issues:
193 * -# \b variable \b scope \n
194 * Variables which are used in the CLEANUP or CATCH clauses must be
195 * declared before the TRY clause, otherwise they only exist inside the
196 * TRY block. In the example above, cp1, cp2 and cp3 only exist in the
197 * TRY block and are invisible from the CLEANUP and CATCH
199 * -# \b variable \b initialization \n
200 * Variables which are used in the CLEANUP or CATCH clauses must
201 * be initialized before the point of the first possible THROW is
202 * reached. In the example above, CLEANUP would have trouble using cp3
203 * if mallocex() throws a exception when allocating a TOOBIG buffer.
204 * -# \b volatile \b variable \n
205 * Variables which are used in the CLEANUP or CATCH clauses MUST BE
206 * DECLARED AS "volatile", otherwise they might contain outdated
207 * information when an exception is thrown.
208 * -# \b clean \b before \b catch \n
209 * The CLEANUP clause is not only place before the CATCH clause in
210 * the source code, it also occures before in the control flow. So,
211 * resources being cleaned up cannot be used in the CATCH block. In the
212 * example, c3 gets freed before the printf placed in CATCH.
213 * -# \b variable \b uninitialization \n
214 * If resources are passed out of the scope of the
215 * TRY/CLEANUP/CATCH construct, they naturally shouldn't get
216 * cleaned up. The example above does free(3) cp1 in CLEANUP although
217 * its value was affected to globalcontext->first, invalidating this
220 * The following is fixed version of the code (annotated with the pitfall items
224 * \until end_of_good_example
229 /** @brief different kind of errors */
231 unknown_error = 0,/**< unknown error */
232 arg_error, /**< Invalid argument */
233 bound_error, /**< Out of bounds argument */
234 mismatch_error, /**< The provided ID does not match */
235 not_found_error, /**< The searched element was not found */
237 system_error, /**< a syscall did fail */
238 network_error, /**< error while sending/receiving data */
239 timeout_error, /**< not quick enough, dude */
240 thread_error, /**< error while [un]locking */
241 host_error, /**< host failed */
242 tracing_error /**< error during the simulation tracing */
245 XBT_PUBLIC(const char *) xbt_ex_catname(xbt_errcat_t cat);
247 /** @brief Structure describing an exception */
249 char *msg; /**< human readable message */
250 xbt_errcat_t category;
251 /**< category like HTTP (what went wrong) */
252 int value; /**< like errno (why did it went wrong) */
255 /**< whether it was raised remotely */
256 char *host;/**< NULL locally thrown exceptions; full hostname if remote ones */
257 /* FIXME: host should be hostname:port[#thread] */
259 /**< Name of the process who thrown this */
260 int pid; /**< PID of the process who thrown this */
261 char *file;/**< Thrown point */
262 int line; /**< Thrown point */
263 char *func;/**< Thrown point */
266 char **bt_strings; /* only filed on display (or before the network propagation) */
267 void *bt[XBT_BACKTRACE_SIZE];
270 /* declare the context type (private) */
272 __ex_mctx_t *ctx_mctx; /* permanent machine context of enclosing try/catch */
273 volatile int ctx_caught; /* temporary flag whether exception was caught */
274 volatile xbt_ex_t ctx_ex; /* temporary exception storage */
277 /* the static and dynamic initializers for a context structure */
278 #define XBT_CTX_INITIALIZER \
279 { NULL, 0, { /* content */ NULL, unknown_error, 0, \
280 /* throw point*/ 0,NULL, NULL,0, NULL, 0, NULL,\
281 /* backtrace */ 0,NULL,{NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL} } }
282 #define XBT_CTX_INITIALIZE(ctx) \
284 (ctx)->ctx_mctx = NULL; \
285 (ctx)->ctx_caught = 0; \
286 (ctx)->ctx_ex.msg = NULL; \
287 (ctx)->ctx_ex.category = 0; \
288 (ctx)->ctx_ex.value = 0; \
289 (ctx)->ctx_ex.remote = 0; \
290 (ctx)->ctx_ex.host = NULL; \
291 (ctx)->ctx_ex.procname = NULL; \
292 (ctx)->ctx_ex.pid = 0; \
293 (ctx)->ctx_ex.file = NULL; \
294 (ctx)->ctx_ex.line = 0; \
295 (ctx)->ctx_ex.func = NULL; \
296 (ctx)->ctx_ex.bt[0] = NULL; \
297 (ctx)->ctx_ex.bt[1] = NULL; \
298 (ctx)->ctx_ex.bt[2] = NULL; \
299 (ctx)->ctx_ex.bt[3] = NULL; \
300 (ctx)->ctx_ex.bt[4] = NULL; \
301 (ctx)->ctx_ex.bt[5] = NULL; \
302 (ctx)->ctx_ex.bt[6] = NULL; \
303 (ctx)->ctx_ex.bt[7] = NULL; \
304 (ctx)->ctx_ex.bt[8] = NULL; \
305 (ctx)->ctx_ex.bt[9] = NULL; \
306 (ctx)->ctx_ex.used = 0; \
307 (ctx)->ctx_ex.bt_strings = NULL; \
310 /* the exception context */
311 typedef ex_ctx_t *(*ex_ctx_cb_t) (void);
312 XBT_PUBLIC_DATA(ex_ctx_cb_t) __xbt_ex_ctx;
313 extern ex_ctx_t *__xbt_ex_ctx_default(void);
315 /* the termination handler */
316 typedef void (*ex_term_cb_t) (xbt_ex_t *);
317 XBT_PUBLIC_DATA(ex_term_cb_t) __xbt_ex_terminate;
318 extern void __xbt_ex_terminate_default(xbt_ex_t * e);
320 /** @brief Introduce a block where exception may be dealed with
325 ex_ctx_t *__xbt_ex_ctx_ptr = __xbt_ex_ctx(); \
326 int __ex_cleanup = 0; \
327 __ex_mctx_t *__ex_mctx_en; \
328 __ex_mctx_t __ex_mctx_me; \
329 __ex_mctx_en = __xbt_ex_ctx_ptr->ctx_mctx; \
330 __xbt_ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \
331 if (__ex_mctx_save(&__ex_mctx_me)) { \
334 /** @brief optional(!) block for cleanup
340 __xbt_ex_ctx_ptr->ctx_caught = 0; \
342 __ex_mctx_restored(&__ex_mctx_me); \
343 __xbt_ex_ctx_ptr->ctx_caught = 1; \
345 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
352 # define XBT_EX_T_CPLUSPLUSCAST (xbt_ex_t&)
354 # define XBT_EX_T_CPLUSPLUSCAST
358 /** @brief the block for catching (ie, deal with) an exception
364 if (!(__ex_cleanup)) \
365 __xbt_ex_ctx_ptr->ctx_caught = 0; \
367 if (!(__ex_cleanup)) { \
368 __ex_mctx_restored(&__ex_mctx_me); \
369 __xbt_ex_ctx_ptr->ctx_caught = 1; \
372 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
374 if ( !(__xbt_ex_ctx()->ctx_caught) \
375 || ((e) = XBT_EX_T_CPLUSPLUSCAST __xbt_ex_ctx()->ctx_ex, MAYDAY_CATCH(e) 0)) { \
379 #define DO_THROW(e) \
380 /* deal with the exception */ \
381 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
382 __xbt_ex_terminate((xbt_ex_t *)&(e)); /* not catched */\
384 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); /* catched somewhere */ \
385 abort() /* nope, stupid GCC, we won't survive a THROW (this won't be reached) */
387 /** @brief Helper macro for THROWS0-6
390 * @param c: category code (integer)
391 * @param v: value (integer)
392 * @param m: message text
394 * If called from within a TRY/CATCH construct, this exception
395 * is copied into the CATCH relevant variable program control flow
396 * is derouted to the CATCH (after the optional sg_cleanup).
398 * If no TRY/CATCH construct embeeds this call, the program calls
401 * The THROW can be performed everywhere, including inside TRY,
402 * CLEANUP and CATCH blocks.
405 #define _THROW(c,v,m) \
406 do { /* change this sequence into one block */ \
407 ex_ctx_t *_throw_ctx = __xbt_ex_ctx(); \
408 /* build the exception */ \
409 _throw_ctx->ctx_ex.msg = (m); \
410 _throw_ctx->ctx_ex.category = (xbt_errcat_t)(c); \
411 _throw_ctx->ctx_ex.value = (v); \
412 _throw_ctx->ctx_ex.remote = 0; \
413 _throw_ctx->ctx_ex.host = (char*)NULL; \
414 _throw_ctx->ctx_ex.procname = (char*)xbt_procname(); \
415 _throw_ctx->ctx_ex.pid = (*xbt_getpid)(); \
416 _throw_ctx->ctx_ex.file = (char*)__FILE__; \
417 _throw_ctx->ctx_ex.line = __LINE__; \
418 _throw_ctx->ctx_ex.func = (char*)_XBT_FUNCTION; \
419 _throw_ctx->ctx_ex.bt_strings = NULL; \
420 xbt_backtrace_current( (xbt_ex_t *) &(_throw_ctx->ctx_ex) ); \
421 DO_THROW(_throw_ctx->ctx_ex); \
423 /* __xbt_ex_ctx()->ctx_ex.used = backtrace((void**)__xbt_ex_ctx()->ctx_ex.bt,XBT_BACKTRACE_SIZE); */
425 /** @brief Builds and throws an exception with a string taking no arguments
427 #define THROW0(c,v,m) _THROW(c,v,(m?bprintf(m):NULL))
428 /** @brief Builds and throws an exception with a string taking one argument
430 #define THROW1(c,v,m,a1) _THROW(c,v,bprintf(m,a1))
431 /** @brief Builds and throws an exception with a string taking two arguments
433 #define THROW2(c,v,m,a1,a2) _THROW(c,v,bprintf(m,a1,a2))
434 /** @brief Builds and throws an exception with a string taking three arguments
436 #define THROW3(c,v,m,a1,a2,a3) _THROW(c,v,bprintf(m,a1,a2,a3))
437 /** @brief Builds and throws an exception with a string taking four arguments
439 #define THROW4(c,v,m,a1,a2,a3,a4) _THROW(c,v,bprintf(m,a1,a2,a3,a4))
440 /** @brief Builds and throws an exception with a string taking five arguments
442 #define THROW5(c,v,m,a1,a2,a3,a4,a5) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5))
443 /** @brief Builds and throws an exception with a string taking six arguments
445 #define THROW6(c,v,m,a1,a2,a3,a4,a5,a6) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6))
446 /** @brief Builds and throws an exception with a string taking seven arguments
448 #define THROW7(c,v,m,a1,a2,a3,a4,a5,a6,a7) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6,a7))
450 #define THROW_IMPOSSIBLE THROW0(unknown_error,0,"The Impossible Did Happen (yet again)")
451 #define THROW_UNIMPLEMENTED THROW1(unknown_error,0,"Function %s unimplemented",_XBT_FUNCTION)
454 # define DIE_IMPOSSIBLE xbt_assert0(0,"The Impossible Did Happen (yet again)")
456 # define DIE_IMPOSSIBLE exit(1);
459 /** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
464 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
465 __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); \
467 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); \
473 #define _XBT_PRE_RETHROW \
475 char *_xbt_ex_internal_msg = __xbt_ex_ctx()->ctx_ex.msg; \
476 __xbt_ex_ctx()->ctx_ex.msg = bprintf(
477 #define _XBT_POST_RETHROW \
478 _xbt_ex_internal_msg); \
479 free(_xbt_ex_internal_msg); \
484 /** @brief like THROW0, but adding some details to the message of an existing exception
487 #define RETHROW0(msg) _XBT_PRE_RETHROW msg, _XBT_POST_RETHROW
488 /** @brief like THROW1, but adding some details to the message of an existing exception
491 #define RETHROW1(msg,a) _XBT_PRE_RETHROW msg,a, _XBT_POST_RETHROW
492 /** @brief like THROW2, but adding some details to the message of an existing exception
495 #define RETHROW2(msg,a,b) _XBT_PRE_RETHROW msg,a,b, _XBT_POST_RETHROW
496 /** @brief like THROW3, but adding some details to the message of an existing exception
499 #define RETHROW3(msg,a,b,c) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
500 /** @brief like THROW4, but adding some details to the message of an existing exception
503 #define RETHROW4(msg,a,b,c,d) _XBT_PRE_RETHROW msg,a,b,c,d, _XBT_POST_RETHROW
504 /** @brief like THROW5, but adding some details to the message of an existing exception
507 #define RETHROW5(msg,a,b,c,d,e) _XBT_PRE_RETHROW msg,a,b,c,d,e, _XBT_POST_RETHROW
509 /** @brief Exception destructor */
510 XBT_PUBLIC(void) xbt_ex_free(xbt_ex_t e);
512 /** @brief Shows a backtrace of the current location */
513 XBT_PUBLIC(void) xbt_backtrace_display_current(void);
514 /** @brief Captures a backtrace for further use */
515 XBT_PUBLIC(void) xbt_backtrace_current(xbt_ex_t * e);
516 /** @brief Display a previously captured backtrace */
517 XBT_PUBLIC(void) xbt_backtrace_display(xbt_ex_t * e);
522 #endif /* __XBT_EX_H__ */