2 ** OSSP ex - Exception Handling (modified to fit into SimGrid)
3 ** Copyright (c) 2005 Martin Quinson.
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/>
8 ** This file is part of OSSP ex, an exception handling library
9 ** which can be found at http://www.ossp.org/pkg/lib/ex/.
11 ** Permission to use, copy, modify, and distribute this software for
12 ** any purpose with or without fee is hereby granted, provided that
13 ** the above copyright notice and this permission notice appear in all
16 ** THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
17 ** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 ** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 ** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
20 ** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
23 ** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 ** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 ** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 ** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 ** ex.h: exception handling (pre-processor part)
36 #include <xbt/sysdep.h>
38 /* do not include execinfo.h directly since it's not always available.
39 Instead, copy the parts we need (and fake when it's not there) */
40 extern int backtrace (void **__array, int __size);
42 /* required ISO-C standard facilities */
46 /* the machine context */
47 #if defined(__EX_MCTX_MCSC__)
48 #include <ucontext.h> /* POSIX.1 ucontext(3) */
49 #define __ex_mctx_struct ucontext_t uc;
50 #define __ex_mctx_save(mctx) (getcontext(&(mctx)->uc) == 0)
51 #define __ex_mctx_restored(mctx) /* noop */
52 #define __ex_mctx_restore(mctx) (void)setcontext(&(mctx)->uc)
54 #elif defined(__EX_MCTX_SSJLJ__)
55 #include <setjmp.h> /* POSIX.1 sigjmp_buf(3) */
56 #define __ex_mctx_struct sigjmp_buf jb;
57 #define __ex_mctx_save(mctx) (sigsetjmp((mctx)->jb, 1) == 0)
58 #define __ex_mctx_restored(mctx) /* noop */
59 #define __ex_mctx_restore(mctx) (void)siglongjmp((mctx)->jb, 1)
61 #elif defined(__EX_MCTX_SJLJ__) || !defined(__EX_MCTX_CUSTOM__)
62 #include <setjmp.h> /* ISO-C jmp_buf(3) */
63 #define __ex_mctx_struct jmp_buf jb;
64 #define __ex_mctx_save(mctx) (setjmp((mctx)->jb) == 0)
65 #define __ex_mctx_restored(mctx) /* noop */
66 #define __ex_mctx_restore(mctx) (void)longjmp((mctx)->jb, 1)
69 /* declare the machine context type */
70 typedef struct { __ex_mctx_struct } __ex_mctx_t;
72 /** @addtogroup XBT_ex
74 * This module is a small ISO-C++ style exception handling library
75 * for use in the ISO-C language. It allows you to use the paradigm
76 * of throwing and catching exceptions in order to reduce the amount
77 * of error handling code without hindering program robustness.
79 * This is achieved by directly transferring exceptional return codes
80 * (and the program control flow) from the location where the exception
81 * is raised (throw point) to the location where it is handled (catch
82 * point) -- usually from a deeply nested sub-routine to a parent
83 * routine. All intermediate routines no longer have to make sure that
84 * the exceptional return codes from sub-routines are correctly passed
87 * These features are brought to you by a modified version of the libex
88 * library, one of the numerous masterpiece of Ralf S. Engelschall.
90 * @section XBT_ex_intro DESCRIPTION
92 * In SimGrid, exceptions is a triple <\a msg , \a category , \a value>
93 * where \a msg is a human-readable text describing the exceptional
94 * condition, \a code an integer describing what went wrong and \a value
95 * providing a sort of sub-category. (this is different in the original libex).
97 * @section XBT_ex_base BASIC USAGE
99 * \em TRY \b TRIED_BLOCK [\em CLEANUP \b CLEANUP_BLOCK] \em CATCH (variable) \b CATCH_BLOCK
101 * This is the primary syntactical construct provided. It is modeled after the
102 * ISO-C++ try-catch clause and should sound familiar to most of you.
104 * Any exception thrown directly from the TRIED_BLOCK block or from called
105 * subroutines is caught. Cleanups which must be done after this block
106 * (whenever an exception arised or not) should be placed into the optionnal
107 * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should
108 * be placed into the (mandatory) CATCH_BLOCK.
111 * In absence of exception, the control flow goes into the blocks TRIED_BLOCK
112 * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored.
114 * When an exception is thrown, the control flow goes through the following
115 * blocks: TRIED_BLOCK (up to the statement throwing the exception),
116 * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a
117 * variable for inspection inside the CATCH_BLOCK. This variable must be
118 * declared in the outter scope, but its value is only valid within the
122 * - TRY, CLEANUP and CATCH cannot be used separately, they work
123 * only in combination and form a language clause as a whole.
124 * - In contrast to the syntax of other languages (such as C++ or Jave) there
125 * is only one CATCH block and not multiple ones (all exceptions are
126 * of the same \em xbt_ex_t C type).
127 * - the variable of CATCH can naturally be reused in subsequent
129 * - it is possible to nest TRY clauses.
131 * The TRY block is a regular ISO-C language statement block, but it is not
132 * allowed to jump into it via "goto" or longjmp(3) or out of it via "break",
133 * "return", "goto" or longjmp(3) because there is some hidden setup and
134 * cleanup that needs to be done regardless of whether an exception is
135 * caught. Bypassing these steps will break the exception handling facility.
137 * The CLEANUP and CATCH blocks are regular ISO-C language statement
138 * blocks without any restrictions. You are even allowed to throw (and, in the
139 * CATCH block, to re-throw) exceptions.
141 * There is one subtle detail you should remember about TRY blocks:
142 * Variables used in the CLEANUP or CATCH clauses must be declared with
143 * the storage class "volatile", otherwise they might contain outdated
144 * information if an exception it thrown.
147 * This is because you usually do not know which commands in the TRY
148 * were already successful before the exception was thrown (logically speaking)
149 * and because the underlying ISO-C setjmp(3) facility applies those
150 * restrictions (technically speaking). As a matter of fact, value changes
151 * between the TRY and the THROW may be discarded if you forget the
152 * "volatile" keyword.
154 * \section XBT_ex_pitfalls PROGRAMMING PITFALLS
156 * Exception handling is a very elegant and efficient way of dealing with
157 * exceptional situation. Nevertheless it requires additional discipline in
158 * programming and there are a few pitfalls one must be aware of. Look the
159 * following code which shows some pitfalls and contains many errors (assuming
160 * a mallocex() function which throws an exception if malloc(3) fails):
162 * \dontinclude ex_test.c
164 * \until end_of_bad_example
166 * This example raises a few issues:
167 * -# \b variable \b scope \n
168 * Variables which are used in the CLEANUP or CATCH clauses must be
169 * declared before the TRY clause, otherwise they only exist inside the
170 * TRY block. In the example above, cp1, cp2 and cp3 only exist in the
171 * TRY block and are invisible from the CLEANUP and CATCH
173 * -# \b variable \b initialization \n
174 * Variables which are used in the CLEANUP or CATCH clauses must
175 * be initialized before the point of the first possible THROW is
176 * reached. In the example above, CLEANUP would have trouble using cp3
177 * if mallocex() throws a exception when allocating a TOOBIG buffer.
178 * -# \b volatile \b variable \n
179 * Variables which are used in the CLEANUP or CATCH clauses MUST BE
180 * DECLARED AS "volatile", otherwise they might contain outdated
181 * information when an exception is thrown.
182 * -# \b clean \b before \b catch \n
183 * The CLEANUP clause is not only place before the CATCH clause in
184 * the source code, it also occures before in the control flow. So,
185 * resources being cleaned up cannot be used in the CATCH block. In the
186 * example, c3 gets freed before the printf placed in CATCH.
187 * -# \b variable \b uninitialization \n
188 * If resources are passed out of the scope of the
189 * TRY/CLEANUP/CATCH construct, they naturally shouldn't get
190 * cleaned up. The example above does free(3) cp1 in CLEANUP although
191 * its value was affected to globalcontext->first, invalidating this
194 * The following is fixed version of the code (annotated with the pitfall items
198 * \until end_of_good_example
204 unknown_error=0, /**< unknown error */
205 arg_error, /**< Invalid argument */
206 mismatch_error, /**< The provided ID does not match */
207 not_found_error, /**< The searched element was not found */
209 system_error, /**< a syscall did fail */
210 network_error, /**< error while sending/receiving data */
211 timeout_error, /**< not quick enough, dude */
212 thread_error /**< error while [un]locking */
215 const char *xbt_errcat_name(xbt_errcat_t errcode);
217 /** @brief Structure describing an exception */
219 char *msg; /**< human readable message; to be freed */
220 xbt_errcat_t category; /**< category like HTTP (what went wrong) */
221 int value; /**< like errno (why did it went wrong) */
223 char *host; /* NULL for localhost; hostname:port if remote */
225 char *file; /**< to be freed only for remote exceptions */
227 char *func; /**< to be freed only for remote exceptions */
233 /* declare the context type (private) */
235 __ex_mctx_t *ctx_mctx; /* permanent machine context of enclosing try/catch */
236 int ctx_caught; /* temporary flag whether exception was caught */
237 volatile xbt_ex_t ctx_ex; /* temporary exception storage */
240 /* the static and dynamic initializers for a context structure */
241 #define XBT_CTX_INITIALIZER \
242 { NULL, 0, { /* content */ NULL, 0, 0, \
243 /* throw point*/ NULL, NULL, NULL, 0, NULL,\
244 /* backtrace */ {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL},0 } }
245 #define XBT_CTX_INITIALIZE(ctx) \
247 (ctx)->ctx_mctx = NULL; \
248 (ctx)->ctx_caught = 0; \
249 (ctx)->ctx_ex.msg = NULL; \
250 (ctx)->ctx_ex.category = 0; \
251 (ctx)->ctx_ex.value = 0; \
252 (ctx)->ctx_ex.host = NULL; \
253 (ctx)->ctx_ex.procname = NULL; \
254 (ctx)->ctx_ex.file = NULL; \
255 (ctx)->ctx_ex.line = 0; \
256 (ctx)->ctx_ex.func = NULL; \
257 (ctx)->ctx_ex.bt[0] = NULL; \
258 (ctx)->ctx_ex.bt[1] = NULL; \
259 (ctx)->ctx_ex.bt[2] = NULL; \
260 (ctx)->ctx_ex.bt[3] = NULL; \
261 (ctx)->ctx_ex.bt[4] = NULL; \
262 (ctx)->ctx_ex.bt[5] = NULL; \
263 (ctx)->ctx_ex.bt[6] = NULL; \
264 (ctx)->ctx_ex.bt[7] = NULL; \
265 (ctx)->ctx_ex.bt[8] = NULL; \
266 (ctx)->ctx_ex.bt[9] = NULL; \
267 (ctx)->ctx_ex.used = 0; \
270 /* the exception context */
271 typedef ex_ctx_t *(*ex_ctx_cb_t)(void);
272 extern ex_ctx_cb_t __xbt_ex_ctx;
273 extern ex_ctx_t *__xbt_ex_ctx_default(void);
275 /* the termination handler */
276 typedef void (*ex_term_cb_t)(xbt_ex_t *);
277 extern ex_term_cb_t __xbt_ex_terminate;
278 extern void __xbt_ex_terminate_default(xbt_ex_t *e);
280 /** @brief Introduce a block where exception may be dealed with
285 ex_ctx_t *__xbt_ex_ctx_ptr = __xbt_ex_ctx(); \
286 int __ex_cleanup = 0; \
287 __ex_mctx_t *__ex_mctx_en; \
288 __ex_mctx_t __ex_mctx_me; \
289 __ex_mctx_en = __xbt_ex_ctx_ptr->ctx_mctx; \
290 __xbt_ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \
291 if (__ex_mctx_save(&__ex_mctx_me)) { \
294 /** @brief optional(!) block for cleanup
300 __xbt_ex_ctx_ptr->ctx_caught = 0; \
302 __ex_mctx_restored(&__ex_mctx_me); \
303 __xbt_ex_ctx_ptr->ctx_caught = 1; \
305 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
310 /** @brief the block for catching (ie, deal with) an exception
316 if (!(__ex_cleanup)) \
317 __xbt_ex_ctx_ptr->ctx_caught = 0; \
319 if (!(__ex_cleanup)) { \
320 __ex_mctx_restored(&__ex_mctx_me); \
321 __xbt_ex_ctx_ptr->ctx_caught = 1; \
324 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
326 if ( !(__xbt_ex_ctx()->ctx_caught) \
327 || ((e) = __xbt_ex_ctx()->ctx_ex, 0)) { \
331 /** @brief Build an exception from the supplied arguments and throws it
334 * @param c: category code (integer)
335 * @param v: value (integer)
336 * @param m: message text
338 * If called from within a TRY/CATCH construct, this exception
339 * is copied into the CATCH relevant variable program control flow
340 * is derouted to the CATCH (after the optional sg_cleanup).
342 * If no TRY/CATCH construct embeeds this call, the program calls
345 * The THROW can be performed everywhere, including inside TRY,
346 * CLEANUP and CATCH blocks.
349 #define _THROW(c,v,m) \
350 do { /* change this sequence into one block */ \
351 /* build the exception */ \
352 __xbt_ex_ctx()->ctx_ex.msg = (m); \
353 __xbt_ex_ctx()->ctx_ex.category = (c); \
354 __xbt_ex_ctx()->ctx_ex.value = (v); \
355 __xbt_ex_ctx()->ctx_ex.host = (char*)NULL; \
356 __xbt_ex_ctx()->ctx_ex.procname = strdup(xbt_procname()); \
357 __xbt_ex_ctx()->ctx_ex.file = (char*)__FILE__; \
358 __xbt_ex_ctx()->ctx_ex.line = __LINE__; \
359 __xbt_ex_ctx()->ctx_ex.func = (char*)_XBT_FUNCTION; \
360 __xbt_ex_ctx()->ctx_ex.used = backtrace((void**)__xbt_ex_ctx()->ctx_ex.bt,10);\
361 /* deal with the exception */ \
362 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
363 __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); /* not catched */\
365 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); /* catched somewhere */ \
366 abort();/* nope, stupid GCC, we won't survive a THROW (this won't be reached) */ \
369 #define THROW0(c,v,m) _THROW(c,v,(m?bprintf(m):NULL))
370 #define THROW1(c,v,m,a1) _THROW(c,v,bprintf(m,a1))
371 #define THROW2(c,v,m,a1,a2) _THROW(c,v,bprintf(m,a1,a2))
372 #define THROW3(c,v,m,a1,a2,a3) _THROW(c,v,bprintf(m,a1,a2,a3))
373 #define THROW4(c,v,m,a1,a2,a3,a4) _THROW(c,v,bprintf(m,a1,a2,a3,a4))
374 #define THROW5(c,v,m,a1,a2,a3,a4,a5) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5))
375 #define THROW6(c,v,m,a1,a2,a3,a4,a5,a6) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6))
377 #define THROW_IMPOSSIBLE THROW0(unknown_error,0,"The Impossible Did Happen (yet again)")
378 #define DIE_IMPOSSIBLE xbt_assert0(0,"The Impossible Did Happen (yet again)")
379 #define THROW_UNIMPLEMENTED THROW1(unknown_error,0,"Function %s unimplemented",__FUNCTION__)
381 /** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
386 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
387 __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); \
389 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); \
393 /** @brief like RETHROW, but adding some details to the message
398 #define _XBT_PRE_RETHROW \
400 char *_xbt_ex_internal_msg = __xbt_ex_ctx()->ctx_ex.msg; \
401 __xbt_ex_ctx()->ctx_ex.msg = bprintf(
402 #define _XBT_POST_RETHROW \
403 _xbt_ex_internal_msg); \
404 free(_xbt_ex_internal_msg); \
408 #define RETHROW0(msg) _XBT_PRE_RETHROW msg, _XBT_POST_RETHROW
409 #define RETHROW1(msg,a) _XBT_PRE_RETHROW msg,a, _XBT_POST_RETHROW
410 #define RETHROW2(msg,a,b) _XBT_PRE_RETHROW msg,a,b, _XBT_POST_RETHROW
411 #define RETHROW3(msg,a,b,c) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
412 #define RETHROW4(msg,a,b,c,d) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
413 #define RETHROW5(msg,a,b,c,d,e) _XBT_PRE_RETHROW msg,a,b,c,d,e _XBT_POST_RETHROW
415 void xbt_ex_free(xbt_ex_t e);
416 const char * xbt_ex_catname(xbt_errcat_t cat);
418 void xbt_ex_display(xbt_ex_t *e);
421 #endif /* __XBT_EX_H__ */