src/debug.cc

   1 /*
   2  * $Id$
   3  *
   4  * DEBUG: section 00    Debug Routines
   5  * AUTHOR: Harvest Derived
   6  *
   7  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   8  * ----------------------------------------------------------
   9  *
  10  *  Squid is the result of efforts by numerous individuals from
  11  *  the Internet community; see the CONTRIBUTORS file for full
  12  *  details.   Many organizations have provided support for Squid's
  13  *  development; see the SPONSORS file for full details.  Squid is
  14  *  Copyrighted (C) 2001 by the Regents of the University of
  15  *  California; see the COPYRIGHT file for full details.  Squid
  16  *  incorporates software developed and/or copyrighted by other
  17  *  sources; see the CREDITS file for full details.
  18  *
  19  *  This program is free software; you can redistribute it and/or modify
  20  *  it under the terms of the GNU General Public License as published by
  21  *  the Free Software Foundation; either version 2 of the License, or
  22  *  (at your option) any later version.
  23  *
  24  *  This program is distributed in the hope that it will be useful,
  25  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  *  GNU General Public License for more details.
  28  *
  29  *  You should have received a copy of the GNU General Public License
  30  *  along with this program; if not, write to the Free Software
  31  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  32  *
  33  */
  34
  35 #include "config.h"
  36 #include "Debug.h"
  37 #include "SquidTime.h"
  38 #include "util.h"
  39 #include "ipc/Kids.h"
  40
  41 /* for shutting_down flag in xassert() */
  42 #include "globals.h"
  43
  44 char *Debug::debugOptions = NULL;
  45 int Debug::override_X = 0;
  46 int Debug::log_stderr = -1;
  47 bool Debug::log_syslog = false;
  48 int Debug::Levels[MAX_DEBUG_SECTIONS];
  49 int Debug::level;
  50 char *Debug::cache_log = NULL;
  51 int Debug::rotateNumber = -1;
  52 FILE *debug_log = NULL;
  53 static char *debug_log_file = NULL;
  54 static int Ctx_Lock = 0;
  55 static const char *debugLogTime(void);
  56 static const char *debugLogKid(void);
  57 static void ctx_print(void);
  58 #if HAVE_SYSLOG
  59 #ifdef LOG_LOCAL4
  60 static int syslog_facility = 0;
  61 #endif
  62 static void _db_print_syslog(const char *format, va_list args);
  63 #endif
  64 static void _db_print_stderr(const char *format, va_list args);
  65 static void _db_print_file(const char *format, va_list args);
  66
  67 #ifdef _SQUID_MSWIN_
  68 SQUIDCEXTERN LPCRITICAL_SECTION dbg_mutex;
  69 typedef BOOL (WINAPI * PFInitializeCriticalSectionAndSpinCount) (LPCRITICAL_SECTION, DWORD);
  70 #endif
  71
  72 void
  73 _db_print(const char *format,...)
  74 {
  75     char f[BUFSIZ];
  76     f[0]='\0';
  77     va_list args1;
  78     va_list args2;
  79     va_list args3;
  80
  81 #ifdef _SQUID_MSWIN_
  82     /* Multiple WIN32 threads may call this simultaneously */
  83
  84     if (!dbg_mutex) {
  85         HMODULE krnl_lib = GetModuleHandle("Kernel32");
  86         PFInitializeCriticalSectionAndSpinCount InitializeCriticalSectionAndSpinCount = NULL;
  87
  88         if (krnl_lib)
  89             InitializeCriticalSectionAndSpinCount =
  90                 (PFInitializeCriticalSectionAndSpinCount) GetProcAddress(krnl_lib,
  91                         "InitializeCriticalSectionAndSpinCount");
  92
  93         dbg_mutex = static_cast<CRITICAL_SECTION*>(xcalloc(1, sizeof(CRITICAL_SECTION)));
  94
  95         if (InitializeCriticalSectionAndSpinCount) {
  96             /* let multiprocessor systems EnterCriticalSection() fast */
  97
  98             if (!InitializeCriticalSectionAndSpinCount(dbg_mutex, 4000)) {
  99                 if (debug_log) {
 100                     fprintf(debug_log, "FATAL: _db_print: can't initialize critical section\n");
 101                     fflush(debug_log);
 102                 }
 103
 104                 fprintf(stderr, "FATAL: _db_print: can't initialize critical section\n");
 105                 abort();
 106             } else
 107                 InitializeCriticalSection(dbg_mutex);
 108         }
 109     }
 110
 111     EnterCriticalSection(dbg_mutex);
 112 #endif
 113
 114     /* give a chance to context-based debugging to print current context */
 115     if (!Ctx_Lock)
 116         ctx_print();
 117
 118     va_start(args1, format);
 119     va_start(args2, format);
 120     va_start(args3, format);
 121
 122     snprintf(f, BUFSIZ, "%s%s| %s",
 123              debugLogTime(),
 124              debugLogKid(),
 125              format);
 126
 127     _db_print_file(f, args1);
 128     _db_print_stderr(f, args2);
 129
 130 #if HAVE_SYSLOG
 131     _db_print_syslog(format, args3);
 132 #endif
 133
 134 #ifdef _SQUID_MSWIN_
 135     LeaveCriticalSection(dbg_mutex);
 136 #endif
 137
 138     va_end(args1);
 139     va_end(args2);
 140     va_end(args3);
 141 }
 142
 143 static void
 144 _db_print_file(const char *format, va_list args)
 145 {
 146     if (debug_log == NULL)
 147         return;
 148
 149     /* give a chance to context-based debugging to print current context */
 150     if (!Ctx_Lock)
 151         ctx_print();
 152
 153     vfprintf(debug_log, format, args);
 154     fflush(debug_log);
 155 }
 156
 157 static void
 158 _db_print_stderr(const char *format, va_list args)
 159 {
 160     if (Debug::log_stderr < Debug::level)
 161         return;
 162
 163     if (debug_log == stderr)
 164         return;
 165
 166     vfprintf(stderr, format, args);
 167 }
 168
 169 #if HAVE_SYSLOG
 170 static void
 171 _db_print_syslog(const char *format, va_list args)
 172 {
 173     /* level 0,1 go to syslog */
 174
 175     if (Debug::level > 1)
 176         return;
 177
 178     if (!Debug::log_syslog)
 179         return;
 180
 181     char tmpbuf[BUFSIZ];
 182     tmpbuf[0] = '\0';
 183
 184     vsnprintf(tmpbuf, BUFSIZ, format, args);
 185
 186     tmpbuf[BUFSIZ - 1] = '\0';
 187
 188     syslog(Debug::level == 0 ? LOG_WARNING : LOG_NOTICE, "%s", tmpbuf);
 189 }
 190 #endif /* HAVE_SYSLOG */
 191
 192 static void
 193 debugArg(const char *arg)
 194 {
 195     int s = 0;
 196     int l = 0;
 197     int i;
 198
 199     if (!strncasecmp(arg, "rotate=", 7)) {
 200         arg += 7;
 201         Debug::rotateNumber = atoi(arg);
 202         return;
 203     } else if (!strncasecmp(arg, "ALL", 3)) {
 204         s = -1;
 205         arg += 4;
 206     } else {
 207         s = atoi(arg);
 208         while (*arg && *arg++ != ',');
 209     }
 210
 211     l = atoi(arg);
 212     assert(s >= -1);
 213
 214     if (s >= MAX_DEBUG_SECTIONS)
 215         s = MAX_DEBUG_SECTIONS-1;
 216
 217     if (l < 0)
 218         l = 0;
 219
 220     if (l > 10)
 221         l = 10;
 222
 223     if (s >= 0) {
 224         Debug::Levels[s] = l;
 225         return;
 226     }
 227
 228     for (i = 0; i < MAX_DEBUG_SECTIONS; i++)
 229         Debug::Levels[i] = l;
 230 }
 231
 232 static void
 233 debugOpenLog(const char *logfile)
 234 {
 235     if (logfile == NULL) {
 236         debug_log = stderr;
 237         return;
 238     }
 239
 240     if (debug_log_file)
 241         xfree(debug_log_file);
 242
 243     debug_log_file = xstrdup(logfile);  /* keep a static copy */
 244
 245     if (debug_log && debug_log != stderr)
 246         fclose(debug_log);
 247
 248     debug_log = fopen(logfile, "a+");
 249
 250     if (!debug_log) {
 251         fprintf(stderr, "WARNING: Cannot write log file: %s\n", logfile);
 252         perror(logfile);
 253         fprintf(stderr, "         messages will be sent to 'stderr'.\n");
 254         fflush(stderr);
 255         debug_log = stderr;
 256     }
 257
 258 #if _SQUID_WINDOWS_
 259     setmode(fileno(debug_log), O_TEXT);
 260 #endif
 261 }
 262
 263 #if HAVE_SYSLOG
 264 #ifdef LOG_LOCAL4
 265
 266 static struct syslog_facility_name {
 267     const char *name;
 268     int facility;
 269 }
 270
 271 syslog_facility_names[] = {
 272
 273 #ifdef LOG_AUTH
 274     {
 275         "auth", LOG_AUTH
 276     },
 277 #endif
 278 #ifdef LOG_AUTHPRIV
 279     {
 280         "authpriv", LOG_AUTHPRIV
 281     },
 282 #endif
 283 #ifdef LOG_CRON
 284     {
 285         "cron", LOG_CRON
 286     },
 287 #endif
 288 #ifdef LOG_DAEMON
 289     {
 290         "daemon", LOG_DAEMON
 291     },
 292 #endif
 293 #ifdef LOG_FTP
 294     {
 295         "ftp", LOG_FTP
 296     },
 297 #endif
 298 #ifdef LOG_KERN
 299     {
 300         "kern", LOG_KERN
 301     },
 302 #endif
 303 #ifdef LOG_LPR
 304     {
 305         "lpr", LOG_LPR
 306     },
 307 #endif
 308 #ifdef LOG_MAIL
 309     {
 310         "mail", LOG_MAIL
 311     },
 312 #endif
 313 #ifdef LOG_NEWS
 314     {
 315         "news", LOG_NEWS
 316     },
 317 #endif
 318 #ifdef LOG_SYSLOG
 319     {
 320         "syslog", LOG_SYSLOG
 321     },
 322 #endif
 323 #ifdef LOG_USER
 324     {
 325         "user", LOG_USER
 326     },
 327 #endif
 328 #ifdef LOG_UUCP
 329     {
 330         "uucp", LOG_UUCP
 331     },
 332 #endif
 333 #ifdef LOG_LOCAL0
 334     {
 335         "local0", LOG_LOCAL0
 336     },
 337 #endif
 338 #ifdef LOG_LOCAL1
 339     {
 340         "local1", LOG_LOCAL1
 341     },
 342 #endif
 343 #ifdef LOG_LOCAL2
 344     {
 345         "local2", LOG_LOCAL2
 346     },
 347 #endif
 348 #ifdef LOG_LOCAL3
 349     {
 350         "local3", LOG_LOCAL3
 351     },
 352 #endif
 353 #ifdef LOG_LOCAL4
 354     {
 355         "local4", LOG_LOCAL4
 356     },
 357 #endif
 358 #ifdef LOG_LOCAL5
 359     {
 360         "local5", LOG_LOCAL5
 361     },
 362 #endif
 363 #ifdef LOG_LOCAL6
 364     {
 365         "local6", LOG_LOCAL6
 366     },
 367 #endif
 368 #ifdef LOG_LOCAL7
 369     {
 370         "local7", LOG_LOCAL7
 371     },
 372 #endif
 373     {
 374         NULL, 0
 375     }
 376 };
 377
 378 #endif
 379
 380 void
 381 _db_set_syslog(const char *facility)
 382 {
 383     Debug::log_syslog = true;
 384
 385 #ifdef LOG_LOCAL4
 386 #ifdef LOG_DAEMON
 387
 388     syslog_facility = LOG_DAEMON;
 389 #else
 390
 391     syslog_facility = LOG_LOCAL4;
 392 #endif /* LOG_DAEMON */
 393
 394     if (facility) {
 395
 396         struct syslog_facility_name *n;
 397
 398         for (n = syslog_facility_names; n->name; n++) {
 399             if (strcmp(n->name, facility) == 0) {
 400                 syslog_facility = n->facility;
 401                 return;
 402             }
 403         }
 404
 405         fprintf(stderr, "unknown syslog facility '%s'\n", facility);
 406         exit(1);
 407     }
 408
 409 #else
 410     if (facility)
 411         fprintf(stderr, "syslog facility type not supported on your system\n");
 412
 413 #endif /* LOG_LOCAL4 */
 414 }
 415
 416 #endif
 417
 418 void
 419 Debug::parseOptions(char const *options)
 420 {
 421     int i;
 422     char *p = NULL;
 423     char *s = NULL;
 424
 425     if (override_X) {
 426         debugs(0, 9, "command-line -X overrides: " << options);
 427         return;
 428     }
 429
 430     for (i = 0; i < MAX_DEBUG_SECTIONS; i++)
 431         Debug::Levels[i] = 0;
 432
 433     if (options) {
 434         p = xstrdup(options);
 435
 436         for (s = strtok(p, w_space); s; s = strtok(NULL, w_space))
 437             debugArg(s);
 438
 439         xfree(p);
 440     }
 441 }
 442
 443 void
 444 _db_init(const char *logfile, const char *options)
 445 {
 446     Debug::parseOptions(options);
 447
 448     debugOpenLog(logfile);
 449
 450 #if HAVE_SYSLOG && defined(LOG_LOCAL4)
 451
 452     if (Debug::log_syslog)
 453         openlog(APP_SHORTNAME, LOG_PID | LOG_NDELAY | LOG_CONS, syslog_facility);
 454
 455 #endif /* HAVE_SYSLOG */
 456
 457     /* Pre-Init TZ env, see bug #2656 */
 458     tzset();
 459 }
 460
 461 void
 462 _db_rotate_log(void)
 463 {
 464     if (debug_log_file == NULL)
 465         return;
 466
 467 #ifdef S_ISREG
 468     struct stat sb;
 469     if (stat(debug_log_file, &sb) == 0)
 470         if (S_ISREG(sb.st_mode) == 0)
 471             return;
 472 #endif
 473
 474     char from[MAXPATHLEN];
 475     from[0] = '\0';
 476
 477     char to[MAXPATHLEN];
 478     to[0] = '\0';
 479
 480     /*
 481      * NOTE: we cannot use xrename here without having it in a
 482      * separate file -- tools.c has too many dependencies to be
 483      * used everywhere debug.c is used.
 484      */
 485     /* Rotate numbers 0 through N up one */
 486     for (int i = Debug::rotateNumber; i > 1;) {
 487         i--;
 488         snprintf(from, MAXPATHLEN, "%s.%d", debug_log_file, i - 1);
 489         snprintf(to, MAXPATHLEN, "%s.%d", debug_log_file, i);
 490 #ifdef _SQUID_MSWIN_
 491         remove
 492         (to);
 493 #endif
 494         rename(from, to);
 495     }
 496
 497     /*
 498      * You can't rename open files on Microsoft "operating systems"
 499      * so we close before renaming.
 500      */
 501 #ifdef _SQUID_MSWIN_
 502     if (debug_log != stderr)
 503         fclose(debug_log);
 504 #endif
 505     /* Rotate the current log to .0 */
 506     if (Debug::rotateNumber > 0) {
 507         snprintf(to, MAXPATHLEN, "%s.%d", debug_log_file, 0);
 508 #ifdef _SQUID_MSWIN_
 509         remove
 510         (to);
 511 #endif
 512         rename(debug_log_file, to);
 513     }
 514
 515     /* Close and reopen the log.  It may have been renamed "manually"
 516      * before HUP'ing us. */
 517     if (debug_log != stderr)
 518         debugOpenLog(Debug::cache_log);
 519 }
 520
 521 static const char *
 522 debugLogTime(void)
 523 {
 524
 525     time_t t = getCurrentTime();
 526
 527     struct tm *tm;
 528     static char buf[128];
 529     static time_t last_t = 0;
 530
 531     if (Debug::level > 1) {
 532         char buf2[128];
 533         tm = localtime(&t);
 534         strftime(buf2, 127, "%Y/%m/%d %H:%M:%S", tm);
 535         buf2[127] = '\0';
 536         snprintf(buf, 127, "%s.%03d", buf2, (int) current_time.tv_usec / 1000);
 537         last_t = t;
 538     } else if (t != last_t) {
 539         tm = localtime(&t);
 540         strftime(buf, 127, "%Y/%m/%d %H:%M:%S", tm);
 541         last_t = t;
 542     }
 543
 544     buf[127] = '\0';
 545     return buf;
 546 }
 547
 548 static const char *
 549 debugLogKid(void)
 550 {
 551     if (KidIdentifier != 0) {
 552         static char buf[16];
 553         if (!*buf) // optimization: fill only once after KidIdentifier is set
 554             snprintf(buf, sizeof(buf), " kid%d", KidIdentifier);
 555         return buf;
 556     }
 557
 558     return "";
 559 }
 560
 561 void
 562 xassert(const char *msg, const char *file, int line)
 563 {
 564     debugs(0, 0, "assertion failed: " << file << ":" << line << ": \"" << msg << "\"");
 565
 566     if (!shutting_down)
 567         abort();
 568 }
 569
 570 /*
 571  * Context-based Debugging
 572  *
 573  * Rationale
 574  * ---------
 575  *
 576  * When you have a long nested processing sequence, it is often impossible
 577  * for low level routines to know in what larger context they operate. If a
 578  * routine coredumps, one can restore the context using debugger trace.
 579  * However, in many case you do not want to coredump, but just want to report
 580  * a potential problem. A report maybe useless out of problem context.
 581  *
 582  * To solve this potential problem, use the following approach:
 583  *
 584  * int
 585  * top_level_foo(const char *url)
 586  * {
 587  *      // define current context
 588  *      // note: we stack but do not dup ctx descriptions!
 589  *      Ctx ctx = ctx_enter(url);
 590  *      ...
 591  *      // go down; middle_level_bar will eventually call bottom_level_boo
 592  *      middle_level_bar(method, protocol);
 593  *      ...
 594  *      // exit, clean after yourself
 595  *      ctx_exit(ctx);
 596  * }
 597  *
 598  * void
 599  * bottom_level_boo(int status, void *data)
 600  * {
 601  *      // detect exceptional condition, and simply report it, the context
 602  *      // information will be available somewhere close in the log file
 603  *      if (status == STRANGE_STATUS)
 604  *      debugs(13, 6, "DOS attack detected, data: " << data);
 605  *      ...
 606  * }
 607  *
 608  * Current implementation is extremely simple but still very handy. It has a
 609  * negligible overhead (descriptions are not duplicated).
 610  *
 611  * When the _first_ debug message for a given context is printed, it is
 612  * prepended with the current context description. Context is printed with
 613  * the same debugging level as the original message.
 614  *
 615  * Note that we do not print context every type you do ctx_enter(). This
 616  * approach would produce too many useless messages.  For the same reason, a
 617  * context description is printed at most _once_ even if you have 10
 618  * debugging messages within one context.
 619  *
 620  * Contexts can be nested, of course. You must use ctx_enter() to enter a
 621  * context (push it onto stack).  It is probably safe to exit several nested
 622  * contexts at _once_ by calling ctx_exit() at the top level (this will pop
 623  * all context till current one). However, as in any stack, you cannot start
 624  * in the middle.
 625  *
 626  * Analysis:
 627  * i)   locate debugging message,
 628  * ii)  locate current context by going _upstream_ in your log file,
 629  * iii) hack away.
 630  *
 631  *
 632  * To-Do:
 633  * -----
 634  *
 635  *       decide if we want to dup() descriptions (adds overhead) but allows to
 636  *       add printf()-style interface
 637  *
 638  * implementation:
 639  * ---------------
 640  *
 641  * descriptions for contexts over CTX_MAX_LEVEL limit are ignored, you probably
 642  * have a bug if your nesting goes that deep.
 643  */
 644
 645 #define CTX_MAX_LEVEL 255
 646
 647 /*
 648  * produce a warning when nesting reaches this level and then double
 649  * the level
 650  */
 651 static int Ctx_Warn_Level = 32;
 652 /* all descriptions has been printed up to this level */
 653 static int Ctx_Reported_Level = -1;
 654 /* descriptions are still valid or active up to this level */
 655 static int Ctx_Valid_Level = -1;
 656 /* current level, the number of nested ctx_enter() calls */
 657 static int Ctx_Current_Level = -1;
 658 /* saved descriptions (stack) */
 659 static const char *Ctx_Descrs[CTX_MAX_LEVEL + 1];
 660 /* "safe" get secription */
 661 static const char *ctx_get_descr(Ctx ctx);
 662
 663
 664 Ctx
 665 ctx_enter(const char *descr)
 666 {
 667     Ctx_Current_Level++;
 668
 669     if (Ctx_Current_Level <= CTX_MAX_LEVEL)
 670         Ctx_Descrs[Ctx_Current_Level] = descr;
 671
 672     if (Ctx_Current_Level == Ctx_Warn_Level) {
 673         debugs(0, 0, "# ctx: suspiciously deep (" << Ctx_Warn_Level << ") nesting:");
 674         Ctx_Warn_Level *= 2;
 675     }
 676
 677     return Ctx_Current_Level;
 678 }
 679
 680 void
 681 ctx_exit(Ctx ctx)
 682 {
 683     assert(ctx >= 0);
 684     Ctx_Current_Level = (ctx >= 0) ? ctx - 1 : -1;
 685
 686     if (Ctx_Valid_Level > Ctx_Current_Level)
 687         Ctx_Valid_Level = Ctx_Current_Level;
 688 }
 689
 690 /*
 691  * the idea id to print each context description at most once but provide enough
 692  * info for deducing the current execution stack
 693  */
 694 static void
 695 ctx_print(void)
 696 {
 697     /* lock so _db_print will not call us recursively */
 698     Ctx_Lock++;
 699     /* ok, user saw [0,Ctx_Reported_Level] descriptions */
 700     /* first inform about entries popped since user saw them */
 701
 702     if (Ctx_Valid_Level < Ctx_Reported_Level) {
 703         if (Ctx_Reported_Level != Ctx_Valid_Level + 1)
 704             _db_print("ctx: exit levels from %2d down to %2d\n",
 705                       Ctx_Reported_Level, Ctx_Valid_Level + 1);
 706         else
 707             _db_print("ctx: exit level %2d\n", Ctx_Reported_Level);
 708
 709         Ctx_Reported_Level = Ctx_Valid_Level;
 710     }
 711
 712     /* report new contexts that were pushed since last report */
 713     while (Ctx_Reported_Level < Ctx_Current_Level) {
 714         Ctx_Reported_Level++;
 715         Ctx_Valid_Level++;
 716         _db_print("ctx: enter level %2d: '%s'\n", Ctx_Reported_Level,
 717                   ctx_get_descr(Ctx_Reported_Level));
 718     }
 719
 720     /* unlock */
 721     Ctx_Lock--;
 722 }
 723
 724 /* checks for nulls and overflows */
 725 static const char *
 726 ctx_get_descr(Ctx ctx)
 727 {
 728     if (ctx < 0 || ctx > CTX_MAX_LEVEL)
 729         return "<lost>";
 730
 731     return Ctx_Descrs[ctx] ? Ctx_Descrs[ctx] : "<null>";
 732 }
 733
 734 int Debug::TheDepth = 0;
 735
 736 std::ostream &
 737 Debug::getDebugOut()
 738 {
 739     assert(TheDepth >= 0);
 740     ++TheDepth;
 741     if (TheDepth > 1) {
 742         assert(CurrentDebug);
 743         *CurrentDebug << std::endl << "reentrant debuging " << TheDepth << "-{";
 744     } else {
 745         assert(!CurrentDebug);
 746         CurrentDebug = new std::ostringstream();
 747         // set default formatting flags
 748         CurrentDebug->setf(std::ios::fixed);
 749         CurrentDebug->precision(2);
 750     }
 751     return *CurrentDebug;
 752 }
 753
 754 void
 755 Debug::finishDebug()
 756 {
 757     assert(TheDepth >= 0);
 758     assert(CurrentDebug);
 759     if (TheDepth > 1) {
 760         *CurrentDebug << "}-" << TheDepth << std::endl;
 761     } else {
 762         assert(TheDepth == 1);
 763         _db_print("%s\n", CurrentDebug->str().c_str());
 764         delete CurrentDebug;
 765         CurrentDebug = NULL;
 766     }
 767     --TheDepth;
 768 }
 769
 770 // Hack: replaces global ::xassert() to debug debugging assertions
 771 // Relies on assert macro calling xassert() without a specific scope.
 772 void
 773 Debug::xassert(const char *msg, const char *file, int line)
 774 {
 775
 776     if (CurrentDebug) {
 777         *CurrentDebug << "assertion failed: " << file << ":" << line <<
 778         ": \"" << msg << "\"";
 779     }
 780     abort();
 781 }
 782
 783 std::ostringstream (*Debug::CurrentDebug)(NULL);
 784
 785 size_t
 786 BuildPrefixInit()
 787 {
 788     // XXX: This must be kept in sync with the actual debug.cc location
 789     const char *ThisFileNameTail = "src/debug.cc";
 790
 791     const char *file=__FILE__;
 792
 793     // Disable heuristic if it does not work.
 794     if (!strstr(file, ThisFileNameTail))
 795         return 0;
 796
 797     return strlen(file)-strlen(ThisFileNameTail);
 798 }
 799
 800 const char*
 801 SkipBuildPrefix(const char* path)
 802 {
 803     static const size_t BuildPrefixLength = BuildPrefixInit();
 804
 805     return path+BuildPrefixLength;
 806 }