epan/except.c

   1 /*
   2  * Portable Exception Handling for ANSI C.
   3  * Copyright (C) 1999 Kaz Kylheku <kaz@ashi.footprints.net>
   4  *
   5  * $Id$
   6  *
   7  * Free Software License:
   8  *
   9  * All rights are reserved by the author, with the following exceptions:
  10  * Permission is granted to freely reproduce and distribute this software,
  11  * possibly in exchange for a fee, provided that this copyright notice appears
  12  * intact. Permission is also granted to adapt this software to produce
  13  * derivative works, as long as the modified versions carry this copyright
  14  * notice and additional notices stating that the work has been modified.
  15  * This source code may be translated into executable form and incorporated
  16  * into proprietary software; there is no requirement for such software to
  17  * contain a copyright notice related to this source.
  18  */
  19
  20 /*
  21  * Modified to support throwing an exception with a null message pointer,
  22  * and to have the message not be const (as we generate messages with
  23  * "g_strdup_sprintf()", which means they need to be freed; using
  24  * a null message means that we don't have to use a special string
  25  * for exceptions with no message, and don't have to worry about
  26  * not freeing that).
  27  */
  28
  29 #include "config.h"
  30
  31 #include <assert.h>
  32 #include <stdlib.h>
  33 #include <stdio.h>
  34 #include <stdarg.h>
  35 #include <limits.h>
  36
  37 #include <glib.h>
  38
  39 #include "except.h"
  40
  41 #ifdef _WIN32
  42 #if _MSC_VER < 1500
  43 /* IsDebuggerPresent() needs this #define! */
  44 #define _WIN32_WINNT 0x0400
  45 #endif
  46 #include <windows.h>
  47 #include "exceptions.h"
  48 #endif
  49
  50 #define XCEPT_BUFFER_SIZE       1024
  51
  52 #ifdef KAZLIB_POSIX_THREADS
  53
  54 #include <pthread.h>
  55
  56 static pthread_mutex_t init_mtx = PTHREAD_MUTEX_INITIALIZER;
  57 static int init_counter;
  58 static pthread_key_t top_key;
  59 static pthread_key_t uh_key;
  60 static pthread_key_t alloc_key;
  61 static pthread_key_t dealloc_key;
  62 static void unhandled_catcher(except_t *);
  63
  64 #define get_top() ((struct except_stacknode *) pthread_getspecific(top_key))
  65 #define set_top(T) (pthread_setspecific(top_key, (T)), (void)((T) == (struct except_stacknode *) 0))
  66 #define set_catcher(C) (pthread_setspecific(uh_key, (void *) (C)), (void)((C) == (void (*)(except_t *)) 0))
  67 #define set_alloc(A) (pthread_setspecific(alloc_key, (void *) (A)), (void)((A) == (void *(*)(size_t)) 0))
  68 #define set_dealloc(D) (pthread_setspecific(dealloc_key, (void *) (D)), (void)((D) == (void (*)(void *)) 0))
  69
  70 static void (*get_catcher(void))(except_t *)
  71 {
  72     void (*catcher)(except_t *) = (void (*)(except_t *)) pthread_getspecific(uh_key);
  73     return (catcher == 0) ? unhandled_catcher : catcher;
  74 }
  75
  76 static void *(*get_alloc(void))(size_t)
  77 {
  78     void *(*alloc)(size_t) = (void *(*)(size_t)) pthread_getspecific(alloc_key);
  79     return (alloc == 0) ? malloc : alloc;
  80 }
  81
  82 static void (*get_dealloc(void))(void *)
  83 {
  84     void (*dealloc)(void *) = (void (*)(void *)) pthread_getspecific(dealloc_key);
  85     return (dealloc == 0) ? free : dealloc;
  86 }
  87
  88 int except_init(void)
  89 {
  90     int retval = 1;
  91
  92     pthread_mutex_lock(&init_mtx);
  93
  94     assert (init_counter < INT_MAX);
  95
  96     if (init_counter++ == 0) {
  97         int top_ok = (pthread_key_create(&top_key, 0) == 0);
  98         int uh_ok = (pthread_key_create(&uh_key, 0) == 0);
  99         int alloc_ok = (pthread_key_create(&alloc_key, 0) == 0);
 100         int dealloc_ok = (pthread_key_create(&dealloc_key, 0) == 0);
 101
 102         if (!top_ok || !uh_ok || !alloc_ok || !dealloc_ok) {
 103             retval = 0;
 104             init_counter = 0;
 105             if (top_ok)
 106                 pthread_key_delete(top_key);
 107             if (uh_ok)
 108                 pthread_key_delete(uh_key);
 109             if (alloc_ok)
 110                 pthread_key_delete(alloc_key);
 111             if (dealloc_ok)
 112                 pthread_key_delete(dealloc_key);
 113         }
 114     }
 115
 116     pthread_mutex_unlock(&init_mtx);
 117
 118     return retval;
 119 }
 120
 121 void except_deinit(void)
 122 {
 123     pthread_mutex_lock(&init_mtx);
 124
 125     assert (init_counter > 0);
 126
 127     if (--init_counter == 0) {
 128         pthread_key_delete(top_key);
 129         pthread_key_delete(uh_key);
 130         pthread_key_delete(alloc_key);
 131         pthread_key_delete(dealloc_key);
 132     }
 133
 134     pthread_mutex_unlock(&init_mtx);
 135 }
 136
 137 #else   /* no thread support */
 138
 139 static int init_counter;
 140 static void unhandled_catcher(except_t *);
 141 static void (*uh_catcher_ptr)(except_t *) = unhandled_catcher;
 142 /* We need this 'size_t' cast due to a glitch in GLib where g_malloc was prototyped
 143  * as 'gpointer g_malloc (gulong n_bytes)'. This was later fixed to the correct prototype
 144  * 'gpointer g_malloc (gsize n_bytes)'. In Wireshark we use the latter prototype
 145  * throughout the code. We can get away with this even with older versions of GLib by
 146  * adding a '(void *(*)(size_t))' cast whenever we refer to g_malloc. The only platform
 147  * supported by Wireshark where this isn't safe (sizeof size_t != sizeof gulong) is Win64.
 148  * However, we _always_ bundle the newest version of GLib on this platform so
 149  * the size_t issue doesn't exists here. Pheew.. */
 150 static void *(*allocator)(size_t) = (void *(*)(size_t)) g_malloc;
 151 static void (*deallocator)(void *) = g_free;
 152 static struct except_stacknode *stack_top;
 153
 154 #define get_top() (stack_top)
 155 #define set_top(T) (stack_top = (T))
 156 #define get_catcher() (uh_catcher_ptr)
 157 #define set_catcher(C) (uh_catcher_ptr = (C))
 158 #define get_alloc() (allocator)
 159 #define set_alloc(A) (allocator = (A))
 160 #define get_dealloc() (deallocator)
 161 #define set_dealloc(D) (deallocator = (D))
 162
 163 int except_init(void)
 164 {
 165     assert (init_counter < INT_MAX);
 166     init_counter++;
 167     return 1;
 168 }
 169
 170 void except_deinit(void)
 171 {
 172     assert (init_counter > 0);
 173     init_counter--;
 174 }
 175
 176 #endif
 177
 178
 179 static int match(const volatile except_id_t *thrown, const except_id_t *caught)
 180 {
 181     int group_match = (caught->except_group == XCEPT_GROUP_ANY ||
 182         caught->except_group == thrown->except_group);
 183     int code_match = (caught->except_code == XCEPT_CODE_ANY ||
 184         caught->except_code == thrown->except_code);
 185
 186     return group_match && code_match;
 187 }
 188
 189 G_GNUC_NORETURN WS_MSVC_NORETURN static void do_throw(except_t *except)
 190 {
 191     struct except_stacknode *top;
 192
 193     assert (except->except_id.except_group != 0 &&
 194         except->except_id.except_code != 0);
 195
 196     for (top = get_top(); top != 0; top = top->except_down) {
 197         if (top->except_type == XCEPT_CLEANUP) {
 198             top->except_info.except_cleanup->except_func(top->except_info.except_cleanup->except_context);
 199         } else {
 200             struct except_catch *catcher = top->except_info.except_catcher;
 201             const except_id_t *pi = catcher->except_id;
 202             size_t i;
 203
 204             assert (top->except_type == XCEPT_CATCHER);
 205             except_free(catcher->except_obj.except_dyndata);
 206
 207             for (i = 0; i < catcher->except_size; pi++, i++) {
 208                 if (match(&except->except_id, pi)) {
 209                     catcher->except_obj = *except;
 210                     set_top(top);
 211                     longjmp(catcher->except_jmp, 1);
 212                 }
 213             }
 214         }
 215     }
 216
 217     set_top(top);
 218     get_catcher()(except);      /* unhandled exception */
 219     abort();
 220 }
 221
 222 static void unhandled_catcher(except_t *except)
 223 {
 224     if (except->except_message == NULL) {
 225         fprintf(stderr, "Unhandled exception (group=%ld, code=%ld)\n",
 226                 except->except_id.except_group,
 227                 except->except_id.except_code);
 228     } else {
 229         fprintf(stderr, "Unhandled exception (\"%s\", group=%ld, code=%ld)\n",
 230                 except->except_message, except->except_id.except_group,
 231                 except->except_id.except_code);
 232     }
 233     abort();
 234 }
 235
 236 static void stack_push(struct except_stacknode *node)
 237 {
 238     node->except_down = get_top();
 239     set_top(node);
 240 }
 241
 242 void except_setup_clean(struct except_stacknode *esn,
 243         struct except_cleanup *ecl, void (*cleanf)(void *), void *context)
 244 {
 245     esn->except_type = XCEPT_CLEANUP;
 246     ecl->except_func = cleanf;
 247     ecl->except_context = context;
 248     esn->except_info.except_cleanup = ecl;
 249     stack_push(esn);
 250 }
 251
 252 void except_setup_try(struct except_stacknode *esn,
 253         struct except_catch *ech, const except_id_t id[], size_t size)
 254 {
 255    ech->except_id = id;
 256    ech->except_size = size;
 257    ech->except_obj.except_dyndata = 0;
 258    esn->except_type = XCEPT_CATCHER;
 259    esn->except_info.except_catcher = ech;
 260    stack_push(esn);
 261 }
 262
 263 struct except_stacknode *except_pop(void)
 264 {
 265     struct except_stacknode *top = get_top();
 266     set_top(top->except_down);
 267     return top;
 268 }
 269
 270 G_GNUC_NORETURN WS_MSVC_NORETURN void except_rethrow(except_t *except)
 271 {
 272     struct except_stacknode *top = get_top();
 273     assert (top != 0);
 274     assert (top->except_type == XCEPT_CATCHER);
 275     assert (&top->except_info.except_catcher->except_obj == except);
 276     set_top(top->except_down);
 277     do_throw(except);
 278 }
 279
 280 G_GNUC_NORETURN WS_MSVC_NORETURN void except_throw(long group, long code, const char *msg)
 281 {
 282     except_t except;
 283
 284     except.except_id.except_group = group;
 285     except.except_id.except_code = code;
 286     except.except_message = msg;
 287     except.except_dyndata = 0;
 288
 289 #ifdef _WIN32
 290     if (code == DissectorError && IsDebuggerPresent()) {
 291         DebugBreak();
 292     }
 293 #endif
 294
 295     do_throw(&except);
 296 }
 297
 298 G_GNUC_NORETURN WS_MSVC_NORETURN void except_throwd(long group, long code, const char *msg, void *data)
 299 {
 300     except_t except;
 301
 302     except.except_id.except_group = group;
 303     except.except_id.except_code = code;
 304     except.except_message = msg;
 305     except.except_dyndata = data;
 306
 307     do_throw(&except);
 308 }
 309
 310 /*
 311  * XXX - should we use g_strdup_sprintf() here, so we're not limited by
 312  * XCEPT_BUFFER_SIZE?  We could then just use this to generate formatted
 313  * messages.
 314  */
 315 G_GNUC_NORETURN WS_MSVC_NORETURN void except_throwf(long group, long code, const char *fmt, ...)
 316 {
 317     char *buf = (char *)except_alloc(XCEPT_BUFFER_SIZE);
 318     va_list vl;
 319
 320     va_start (vl, fmt);
 321     g_vsnprintf(buf, XCEPT_BUFFER_SIZE, fmt, vl);
 322     va_end (vl);
 323     except_throwd(group, code, buf, buf);
 324 }
 325
 326 void (*except_unhandled_catcher(void (*new_catcher)(except_t *)))(except_t *)
 327 {
 328     void (*old_catcher)(except_t *) = get_catcher();
 329     set_catcher(new_catcher);
 330     return old_catcher;
 331 }
 332
 333 #undef except_code
 334 #undef except_group
 335 #undef except_message
 336 #undef except_data
 337
 338 unsigned long except_code(except_t *ex)
 339 {
 340     return ex->except_id.except_code;
 341 }
 342
 343 unsigned long except_group(except_t *ex)
 344 {
 345     return ex->except_id.except_group;
 346 }
 347
 348 const char *except_message(except_t *ex)
 349 {
 350     return ex->except_message;
 351 }
 352
 353 void *except_data(except_t *ex)
 354 {
 355     return ex->except_dyndata;
 356 }
 357
 358 void *except_take_data(except_t *ex)
 359 {
 360     void *data = ex->except_dyndata;
 361     ex->except_dyndata = 0;
 362     return data;
 363 }
 364
 365 void except_set_allocator(void *(*alloc)(size_t), void (*dealloc)(void *))
 366 {
 367     set_alloc(alloc);
 368     set_dealloc(dealloc);
 369 }
 370
 371 void *except_alloc(size_t size)
 372 {
 373     void *ptr = get_alloc()(size);
 374
 375     if (ptr == 0)
 376         except_throw(XCEPT_BAD_ALLOC, 0, "out of memory");
 377     return ptr;
 378 }
 379
 380 void except_free(void *ptr)
 381 {
 382     get_dealloc()(ptr);
 383 }
 384
 385 #ifdef KAZLIB_TEST_MAIN
 386
 387 #include <stdio.h>
 388 #include <ctype.h>
 389
 390 static void cleanup(void *arg)
 391 {
 392     printf("cleanup(\"%s\") called\n", (char *) arg);
 393 }
 394
 395 static void bottom_level(void)
 396 {
 397     char buf[256];
 398     printf("throw exception? "); fflush(stdout);
 399     fgets(buf, sizeof buf, stdin);
 400
 401     if (buf[0] >= 0 && toupper(buf[0]) == 'Y')
 402         except_throw(1, 1, "nasty exception");
 403 }
 404
 405 static void top_level(void)
 406 {
 407     except_cleanup_push(cleanup, "argument");
 408     bottom_level();
 409     except_cleanup_pop(0);
 410 }
 411
 412 int main(int argc, char **argv)
 413 {
 414     static const except_id_t catch[] = { { 1, 1 }, { 1, 2 } };
 415     except_t *ex;
 416     char *msg;
 417
 418     /*
 419      * Nested exception ``try blocks''
 420      */
 421
 422     /* outer */
 423     except_try_push(catch, 2, &ex);
 424     if (!ex) {
 425         /* inner */
 426         except_try_push(catch, 2, &ex);
 427         if (!ex) {
 428             top_level();
 429         } else {
 430             /* inner catch */
 431             msg = except_message(ex);
 432             if (msg == NULL) {
 433                 printf("caught exception (inner): s=%ld, c=%ld\n",
 434                        except_group(ex), except_code(ex));
 435             } else {
 436                 printf("caught exception (inner): \"%s\", s=%ld, c=%ld\n",
 437                        msg, except_group(ex), except_code(ex));
 438             }
 439             except_rethrow(ex);
 440         }
 441         except_try_pop();
 442     } else {
 443         /* outer catch */
 444         msg = except_message(ex);
 445         if (msg == NULL) {
 446             printf("caught exception (outer): s=%ld, c=%ld\n",
 447                    except_group(ex), except_code(ex));
 448         } else {
 449             printf("caught exception (outer): \"%s\", s=%ld, c=%ld\n",
 450                    except_message(ex), except_group(ex), except_code(ex));
 451         }
 452     }
 453     except_try_pop();
 454     except_throw(99, 99, "exception in main");
 455     return 0;
 456 }
 457
 458
 459 #endif