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 //#define __EX_MCTX_MCSC__ 1
47 //#define __EX_MCTX_SSJLJ__ 1
48 /* the machine context */
49 #if defined(__EX_MCTX_MCSC__)
50 #include <ucontext.h> /* POSIX.1 ucontext(3) */
51 #define __ex_mctx_struct ucontext_t uc;
52 #define __ex_mctx_save(mctx) (getcontext(&(mctx)->uc) == 0)
53 #define __ex_mctx_restored(mctx) /* noop */
54 #define __ex_mctx_restore(mctx) (void)setcontext(&(mctx)->uc)
56 #elif defined(__EX_MCTX_SSJLJ__)
57 #include <setjmp.h> /* POSIX.1 sigjmp_buf(3) */
58 #define __ex_mctx_struct sigjmp_buf jb;
59 #define __ex_mctx_save(mctx) (sigsetjmp((mctx)->jb, 1) == 0)
60 #define __ex_mctx_restored(mctx) /* noop */
61 #define __ex_mctx_restore(mctx) (void)siglongjmp((mctx)->jb, 1)
63 #elif defined(__EX_MCTX_SJLJ__) || !defined(__EX_MCTX_CUSTOM__)
64 #include <setjmp.h> /* ISO-C jmp_buf(3) */
65 #define __ex_mctx_struct jmp_buf jb;
66 #define __ex_mctx_save(mctx) (setjmp((mctx)->jb) == 0)
67 #define __ex_mctx_restored(mctx) /* noop */
68 #define __ex_mctx_restore(mctx) (void)longjmp((mctx)->jb, 1)
71 /* declare the machine context type */
72 typedef struct { __ex_mctx_struct } __ex_mctx_t;
74 /** @addtogroup XBT_ex
76 * This module is a small ISO-C++ style exception handling library
77 * for use in the ISO-C language. It allows you to use the paradigm
78 * of throwing and catching exceptions in order to reduce the amount
79 * of error handling code without hindering program robustness.
81 * This is achieved by directly transferring exceptional return codes
82 * (and the program control flow) from the location where the exception
83 * is raised (throw point) to the location where it is handled (catch
84 * point) -- usually from a deeply nested sub-routine to a parent
85 * routine. All intermediate routines no longer have to make sure that
86 * the exceptional return codes from sub-routines are correctly passed
89 * These features are brought to you by a modified version of the libex
90 * library, one of the numerous masterpiece of Ralf S. Engelschall.
92 * @section XBT_ex_intro DESCRIPTION
94 * In SimGrid, exceptions is a triple <\a msg , \a category , \a value>
95 * where \a msg is a human-readable text describing the exceptional
96 * condition, \a code an integer describing what went wrong and \a value
97 * providing a sort of sub-category. (this is different in the original libex).
99 * @section XBT_ex_base BASIC USAGE
101 * \em TRY \b TRIED_BLOCK [\em CLEANUP \b CLEANUP_BLOCK] \em CATCH (variable) \b CATCH_BLOCK
103 * This is the primary syntactical construct provided. It is modeled after the
104 * ISO-C++ try-catch clause and should sound familiar to most of you.
106 * Any exception thrown directly from the TRIED_BLOCK block or from called
107 * subroutines is caught. Cleanups which must be done after this block
108 * (whenever an exception arised or not) should be placed into the optionnal
109 * CLEANUP_BLOCK. The code dealing with the exceptions when they arise should
110 * be placed into the (mandatory) CATCH_BLOCK.
113 * In absence of exception, the control flow goes into the blocks TRIED_BLOCK
114 * and CLEANUP_BLOCK (if present); The CATCH_BLOCK block is then ignored.
116 * When an exception is thrown, the control flow goes through the following
117 * blocks: TRIED_BLOCK (up to the statement throwing the exception),
118 * CLEANUP_BLOCK (if any) and CATCH_BLOCK. The exception is stored in a
119 * variable for inspection inside the CATCH_BLOCK. This variable must be
120 * declared in the outter scope, but its value is only valid within the
124 * - TRY, CLEANUP and CATCH cannot be used separately, they work
125 * only in combination and form a language clause as a whole.
126 * - In contrast to the syntax of other languages (such as C++ or Jave) there
127 * is only one CATCH block and not multiple ones (all exceptions are
128 * of the same \em xbt_ex_t C type).
129 * - the variable of CATCH can naturally be reused in subsequent
131 * - it is possible to nest TRY clauses.
133 * The TRY block is a regular ISO-C language statement block, but it is not
134 * allowed to jump into it via "goto" or longjmp(3) or out of it via "break",
135 * "return", "goto" or longjmp(3) because there is some hidden setup and
136 * cleanup that needs to be done regardless of whether an exception is
137 * caught. Bypassing these steps will break the exception handling facility.
139 * The CLEANUP and CATCH blocks are regular ISO-C language statement
140 * blocks without any restrictions. You are even allowed to throw (and, in the
141 * CATCH block, to re-throw) exceptions.
143 * There is one subtle detail you should remember about TRY blocks:
144 * Variables used in the CLEANUP or CATCH clauses must be declared with
145 * the storage class "volatile", otherwise they might contain outdated
146 * information if an exception it thrown.
149 * This is because you usually do not know which commands in the TRY
150 * were already successful before the exception was thrown (logically speaking)
151 * and because the underlying ISO-C setjmp(3) facility applies those
152 * restrictions (technically speaking). As a matter of fact, value changes
153 * between the TRY and the THROW may be discarded if you forget the
154 * "volatile" keyword.
156 * \section XBT_ex_pitfalls PROGRAMMING PITFALLS
158 * Exception handling is a very elegant and efficient way of dealing with
159 * exceptional situation. Nevertheless it requires additional discipline in
160 * programming and there are a few pitfalls one must be aware of. Look the
161 * following code which shows some pitfalls and contains many errors (assuming
162 * a mallocex() function which throws an exception if malloc(3) fails):
164 * \dontinclude ex_test.c
166 * \until end_of_bad_example
168 * This example raises a few issues:
169 * -# \b variable \b scope \n
170 * Variables which are used in the CLEANUP or CATCH clauses must be
171 * declared before the TRY clause, otherwise they only exist inside the
172 * TRY block. In the example above, cp1, cp2 and cp3 only exist in the
173 * TRY block and are invisible from the CLEANUP and CATCH
175 * -# \b variable \b initialization \n
176 * Variables which are used in the CLEANUP or CATCH clauses must
177 * be initialized before the point of the first possible THROW is
178 * reached. In the example above, CLEANUP would have trouble using cp3
179 * if mallocex() throws a exception when allocating a TOOBIG buffer.
180 * -# \b volatile \b variable \n
181 * Variables which are used in the CLEANUP or CATCH clauses MUST BE
182 * DECLARED AS "volatile", otherwise they might contain outdated
183 * information when an exception is thrown.
184 * -# \b clean \b before \b catch \n
185 * The CLEANUP clause is not only place before the CATCH clause in
186 * the source code, it also occures before in the control flow. So,
187 * resources being cleaned up cannot be used in the CATCH block. In the
188 * example, c3 gets freed before the printf placed in CATCH.
189 * -# \b variable \b uninitialization \n
190 * If resources are passed out of the scope of the
191 * TRY/CLEANUP/CATCH construct, they naturally shouldn't get
192 * cleaned up. The example above does free(3) cp1 in CLEANUP although
193 * its value was affected to globalcontext->first, invalidating this
196 * The following is fixed version of the code (annotated with the pitfall items
200 * \until end_of_good_example
206 unknown_error=0, /**< unknown error */
207 arg_error, /**< Invalid argument */
208 mismatch_error, /**< The provided ID does not match */
209 not_found_error, /**< The searched element was not found */
211 system_error, /**< a syscall did fail */
212 network_error, /**< error while sending/receiving data */
213 timeout_error, /**< not quick enough, dude */
214 thread_error /**< error while [un]locking */
217 const char *xbt_errcat_name(xbt_errcat_t errcode);
219 /** @brief Structure describing an exception */
221 char *msg; /**< human readable message; to be freed */
222 xbt_errcat_t category; /**< category like HTTP (what went wrong) */
223 int value; /**< like errno (why did it went wrong) */
225 char *host; /* NULL for localhost; hostname:port if remote */
227 char *file; /**< to be freed only for remote exceptions */
229 char *func; /**< to be freed only for remote exceptions */
235 /* declare the context type (private) */
237 __ex_mctx_t *ctx_mctx; /* permanent machine context of enclosing try/catch */
238 int ctx_caught; /* temporary flag whether exception was caught */
239 volatile xbt_ex_t ctx_ex; /* temporary exception storage */
242 /* the static and dynamic initializers for a context structure */
243 #define XBT_CTX_INITIALIZER \
244 { NULL, 0, { /* content */ NULL, 0, 0, \
245 /* throw point*/ NULL, NULL, NULL, 0, NULL,\
246 /* backtrace */ {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL},0 } }
247 #define XBT_CTX_INITIALIZE(ctx) \
249 (ctx)->ctx_mctx = NULL; \
250 (ctx)->ctx_caught = 0; \
251 (ctx)->ctx_ex.msg = NULL; \
252 (ctx)->ctx_ex.category = 0; \
253 (ctx)->ctx_ex.value = 0; \
254 (ctx)->ctx_ex.host = NULL; \
255 (ctx)->ctx_ex.procname = NULL; \
256 (ctx)->ctx_ex.file = NULL; \
257 (ctx)->ctx_ex.line = 0; \
258 (ctx)->ctx_ex.func = NULL; \
259 (ctx)->ctx_ex.bt[0] = NULL; \
260 (ctx)->ctx_ex.bt[1] = NULL; \
261 (ctx)->ctx_ex.bt[2] = NULL; \
262 (ctx)->ctx_ex.bt[3] = NULL; \
263 (ctx)->ctx_ex.bt[4] = NULL; \
264 (ctx)->ctx_ex.bt[5] = NULL; \
265 (ctx)->ctx_ex.bt[6] = NULL; \
266 (ctx)->ctx_ex.bt[7] = NULL; \
267 (ctx)->ctx_ex.bt[8] = NULL; \
268 (ctx)->ctx_ex.bt[9] = NULL; \
269 (ctx)->ctx_ex.used = 0; \
272 /* the exception context */
273 typedef ex_ctx_t *(*ex_ctx_cb_t)(void);
274 extern ex_ctx_cb_t __xbt_ex_ctx;
275 extern ex_ctx_t *__xbt_ex_ctx_default(void);
277 /* the termination handler */
278 typedef void (*ex_term_cb_t)(xbt_ex_t *);
279 extern ex_term_cb_t __xbt_ex_terminate;
280 extern void __xbt_ex_terminate_default(xbt_ex_t *e) __attribute__((__noreturn__));
282 /** @brief Introduce a block where exception may be dealed with
287 ex_ctx_t *__xbt_ex_ctx_ptr = __xbt_ex_ctx(); \
288 int __ex_cleanup = 0; \
289 __ex_mctx_t *__ex_mctx_en; \
290 __ex_mctx_t __ex_mctx_me; \
291 __ex_mctx_en = __xbt_ex_ctx_ptr->ctx_mctx; \
292 __xbt_ex_ctx_ptr->ctx_mctx = &__ex_mctx_me; \
293 if (__ex_mctx_save(&__ex_mctx_me)) { \
296 /** @brief optional(!) block for cleanup
302 __xbt_ex_ctx_ptr->ctx_caught = 0; \
304 __ex_mctx_restored(&__ex_mctx_me); \
305 __xbt_ex_ctx_ptr->ctx_caught = 1; \
307 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
312 /** @brief the block for catching (ie, deal with) an exception
318 if (!(__ex_cleanup)) \
319 __xbt_ex_ctx_ptr->ctx_caught = 0; \
321 if (!(__ex_cleanup)) { \
322 __ex_mctx_restored(&__ex_mctx_me); \
323 __xbt_ex_ctx_ptr->ctx_caught = 1; \
326 __xbt_ex_ctx_ptr->ctx_mctx = __ex_mctx_en; \
328 if ( !(__xbt_ex_ctx()->ctx_caught) \
329 || ((e) = __xbt_ex_ctx()->ctx_ex, 0)) { \
333 /** @brief Build an exception from the supplied arguments and throws it
336 * @param c: category code (integer)
337 * @param v: value (integer)
338 * @param m: message text
340 * If called from within a TRY/CATCH construct, this exception
341 * is copied into the CATCH relevant variable program control flow
342 * is derouted to the CATCH (after the optional sg_cleanup).
344 * If no TRY/CATCH construct embeeds this call, the program calls
347 * The THROW can be performed everywhere, including inside TRY,
348 * CLEANUP and CATCH blocks.
351 #define _THROW(c,v,m) \
352 do { /* change this sequence into one block */ \
353 /* build the exception */ \
354 __xbt_ex_ctx()->ctx_ex.msg = (m); \
355 __xbt_ex_ctx()->ctx_ex.category = (c); \
356 __xbt_ex_ctx()->ctx_ex.value = (v); \
357 __xbt_ex_ctx()->ctx_ex.host = (char*)NULL; \
358 __xbt_ex_ctx()->ctx_ex.procname = strdup(xbt_procname()); \
359 __xbt_ex_ctx()->ctx_ex.file = (char*)__FILE__; \
360 __xbt_ex_ctx()->ctx_ex.line = __LINE__; \
361 __xbt_ex_ctx()->ctx_ex.func = (char*)_XBT_FUNCTION; \
362 __xbt_ex_ctx()->ctx_ex.used = backtrace((void**)__xbt_ex_ctx()->ctx_ex.bt,10);\
363 /* deal with the exception */ \
364 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
365 __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); /* not catched */\
367 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); /* catched somewhere */ \
368 abort();/* nope, stupid GCC, we won't survive a THROW (this won't be reached) */ \
371 #define THROW0(c,v,m) _THROW(c,v,bprintf(m))
372 #define THROW1(c,v,m,a1) _THROW(c,v,bprintf(m,a1))
373 #define THROW2(c,v,m,a1,a2) _THROW(c,v,bprintf(m,a1,a2))
374 #define THROW3(c,v,m,a1,a2,a3) _THROW(c,v,bprintf(m,a1,a2,a3))
375 #define THROW4(c,v,m,a1,a2,a3,a4) _THROW(c,v,bprintf(m,a1,a2,a3,a4))
376 #define THROW5(c,v,m,a1,a2,a3,a4,a5) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5))
377 #define THROW6(c,v,m,a1,a2,a3,a4,a5,a6) _THROW(c,v,bprintf(m,a1,a2,a3,a4,a5,a6))
379 #define THROW_IMPOSSIBLE THROW0(unknown_error,0,"The Impossible Did Happen (yet again)")
380 #define DIE_IMPOSSIBLE xbt_assert0(0,"The Impossible Did Happen (yet again)")
381 #define THROW_UNIMPLEMENTED THROW1(unknown_error,0,"Function %s unimplemented",__FUNCTION__)
383 /** @brief re-throwing of an already caught exception (ie, pass it to the upper catch block)
388 if (__xbt_ex_ctx()->ctx_mctx == NULL) \
389 __xbt_ex_terminate((xbt_ex_t *)&(__xbt_ex_ctx()->ctx_ex)); \
391 __ex_mctx_restore(__xbt_ex_ctx()->ctx_mctx); \
395 /** @brief like RETHROW, but adding some details to the message
400 #define _XBT_PRE_RETHROW \
402 char *_xbt_ex_internal_msg = __xbt_ex_ctx()->ctx_ex.msg; \
403 __xbt_ex_ctx()->ctx_ex.msg = bprintf(
404 #define _XBT_POST_RETHROW \
405 _xbt_ex_internal_msg); \
406 free(_xbt_ex_internal_msg); \
410 #define RETHROW0(msg) _XBT_PRE_RETHROW msg, _XBT_POST_RETHROW
411 #define RETHROW1(msg,a) _XBT_PRE_RETHROW msg,a, _XBT_POST_RETHROW
412 #define RETHROW2(msg,a,b) _XBT_PRE_RETHROW msg,a,b, _XBT_POST_RETHROW
413 #define RETHROW3(msg,a,b,c) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
414 #define RETHROW4(msg,a,b,c,d) _XBT_PRE_RETHROW msg,a,b,c, _XBT_POST_RETHROW
415 #define RETHROW5(msg,a,b,c,d,e) _XBT_PRE_RETHROW msg,a,b,c,d,e _XBT_POST_RETHROW
417 void xbt_ex_free(xbt_ex_t e);
418 const char * xbt_ex_catname(xbt_errcat_t cat);
421 #endif /* __XBT_EX_H__ */