siginfo.c

   1 /* -*- Mode: C ; c-basic-offset: 4 -*- */
   2 /*
   3  * Copyright (C) 2012 Nedko Arnaudov
   4  *
   5  * print out a stack-trace when program segfaults
   6  *
   7  * Inspiration: sigsegv.c by Jaco Kroon
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program. If not, see <http://www.gnu.org/licenses/>
  21  * or write to the Free Software Foundation, Inc.,
  22  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #if defined(HAVE_CONFIG_H)
  26 # include "config.h"
  27 #endif
  28
  29 /* These are "defined" for documentation purposes. They should come from the build system with or without config.h */
  30 #if 0
  31 # define SIGINFO_CPP_DEMANGLE    /* whether to attempt c++ demangle. if used, you must link with libstdc++ */
  32 # define SIGINFO_AUTO_INIT       /* whether to use gcc constructor function for automatic initialization */
  33 #endif
  34
  35 #if !defined(SIGINFO_TEST)
  36 # if !defined siginfo_log
  37 #  error "siginfo_log not defined"
  38 # endif
  39 #else
  40 # define siginfo_log(fmt, args...) fprintf(stderr, fmt "\n", ##args);
  41 #endif
  42
  43 /* dladdr() is a glibc extension */
  44 #ifndef _GNU_SOURCE
  45 # define _GNU_SOURCE
  46 #endif
  47
  48 #include <memory.h>
  49 #include <stdlib.h>
  50 #include <stdio.h>
  51 #include <signal.h>
  52 #include <dlfcn.h>
  53 #include <execinfo.h>
  54 #include <errno.h>
  55
  56 #define SIGINFO_MAX_BT_FRAMES 20
  57
  58 #if defined(SA_SIGINFO) && !defined(__arm__) && !defined(__ia64__) && !defined(__alpha__) && !defined (__FreeBSD_kernel__) && !defined (__sh__) && !defined(__APPLE__) && !defined(__aarch64__)
  59 # define USE_UCONTEXT
  60 # include <ucontext.h>
  61 #endif
  62
  63 #if defined(__powerpc64__)
  64 # define SIGINFO_REGISTER(ucontext, index) ((ucontext)->uc_mcontext.gp_regs[index])
  65 #elif defined(__powerpc__)
  66 # define SIGINFO_REGISTER(ucontext, index) ((ucontext)->uc_mcontext.uc_regs->gregs[index])
  67 #elif defined(__sparc__) && defined(__arch64__)
  68 # define SIGINFO_REGISTER(ucontext, index) ((ucontext)->uc_mcontext.mc_gregs[index])
  69 #else
  70 # define SIGINFO_REGISTER(ucontext, index) ((ucontext)->uc_mcontext.gregs[index])
  71 #endif
  72
  73 #if defined(REG_RIP)
  74 # define SIGINFO_IP_REG REG_RIP
  75 # define SIGINFO_BP_REG REG_RBP
  76 # define SIGINFO_REGFORMAT "%016llx"
  77 # define UINT_PTR_TYPE unsigned long long
  78 #elif defined(REG_EIP)
  79 # define SIGINFO_IP_REG REG_EIP
  80 # define SIGINFO_BP_REG REG_EBP
  81 # define SIGINFO_REGFORMAT "%08lx"
  82 # define UINT_PTR_TYPE unsigned long
  83 #else
  84 # define SIGINFO_REGFORMAT "%x"
  85 # define SIGINFO_STACK_GENERIC
  86 # define UINT_PTR_TYPE unsigned int
  87 #endif
  88
  89 struct si_code_descriptor
  90 {
  91     int code;
  92     const char * description;
  93 };
  94
  95 #ifdef USE_UCONTEXT
  96 static struct si_code_descriptor sig_ill_codes[] =
  97 {
  98     { ILL_ILLOPC, "ILL_ILLOPC; Illegal opcode" },
  99     { ILL_ILLOPN, "ILL_ILLOPN; Illegal operand" },
 100     { ILL_ILLADR, "ILL_ILLADR; Illegal addressing mode" },
 101     { ILL_ILLTRP, "ILL_ILLTRP; Illegal trap" },
 102     { ILL_PRVOPC, "ILL_PRVOPC; Privileged opcode" },
 103     { ILL_PRVREG, "ILL_PRVREG; Privileged register" },
 104     { ILL_COPROC, "ILL_COPROC; Coprocessor error" },
 105     { ILL_BADSTK, "ILL_BADSTK; Internal stack error" },
 106     { 0, NULL }
 107 };
 108
 109 static struct si_code_descriptor sig_fpe_codes[] =
 110 {
 111     { FPE_INTDIV, "FPE_INTDIV; Integer divide by zero" },
 112     { FPE_INTOVF, "FPE_INTOVF; Integer overflow" },
 113     { FPE_FLTDIV, "FPE_FLTDIV; Floating-point divide by zero" },
 114     { FPE_FLTOVF, "FPE_FLTOVF; Floating-point overflow" },
 115     { FPE_FLTUND, "FPE_FLTUND; Floating-point underflow" },
 116     { FPE_FLTRES, "FPE_FLTRES; Floating-point inexact result" },
 117     { FPE_FLTINV, "FPE_FLTINV; Invalid floating-point operation" },
 118     { FPE_FLTSUB, "FPE_FLTSUB; Subscript out of range" },
 119     { 0, NULL }
 120 };
 121
 122 static struct si_code_descriptor sig_segv_codes[] = {
 123     { SEGV_MAPERR, "SEGV_MAPERR; Address not mapped to object" },
 124     { SEGV_ACCERR, "SEGV_ACCERR; Invalid permissions for mapped object" },
 125     { 0, NULL }
 126 };
 127
 128 static struct si_code_descriptor sig_bus_codes[] =
 129 {
 130     { BUS_ADRALN, "BUS_ADRALN; Invalid address alignment" },
 131     { BUS_ADRERR, "BUS_ADRERR; Nonexistent physical address" },
 132     { BUS_OBJERR, "BUS_OBJERR; Object-specific hardware error" },
 133     { 0, NULL }
 134 };
 135
 136 static struct si_code_descriptor sig_any_codes[] =
 137 {
 138     { SI_USER,    "SI_USER; sent by kill, sigsend, raise" },
 139 #if defined(SI_KERNEL)
 140     { SI_KERNEL,  "SI_KERNEL; sent by the kernel from somewhere" },
 141 #endif
 142     { SI_QUEUE,   "SI_QUEUE; Signal sent by the sigqueue()" },
 143     { SI_TIMER,   "SI_TIMER; Signal generated by expiration of a timer set by timer_settime()" },
 144     { SI_ASYNCIO, "SI_ASYNCIO; Signal generated by completion of an asynchronous I/O request" },
 145     { SI_MESGQ,   "SI_MESGQ; Signal generated by arrival of a message on an empty message queue" },
 146 #if defined(SI_ASYNCIO)
 147     { SI_ASYNCIO, "SI_ASYNCIO; sent by AIO completion" },
 148 #endif
 149 #if defined(SI_SIGIO)
 150     { SI_SIGIO, "SI_SIGIO; sent by queued SIGIO" },
 151 #endif
 152 #if defined(SI_TKILL)
 153     { SI_TKILL, "SI_TKILL; sent by tkill system call" },
 154 #endif
 155 #if defined(SI_DETHREAD)
 156     { SI_DETHREAD, "SI_DETHREAD; sent by execve() killing subsidiary threads" },
 157 #endif
 158     { 0, NULL }
 159 };
 160 #else /* #ifdef USE_UCONTEXT */
 161 # define sig_ill_codes  NULL
 162 # define sig_fpe_codes  NULL
 163 # define sig_segv_codes NULL
 164 # define sig_bus_codes  NULL
 165 #endif /* #ifdef USE_UCONTEXT */
 166
 167 struct signal_descriptor
 168 {
 169     int signo;
 170     const char * descr;
 171     struct si_code_descriptor * codes;
 172     const char * msg;
 173 };
 174
 175 static struct signal_descriptor signal_descriptors[] =
 176 {
 177     { SIGILL,  "SIGILL",  sig_ill_codes,  "Illegal instruction" },
 178     { SIGFPE,  "SIGFPE",  sig_fpe_codes,  "Floating point exception" },
 179     { SIGSEGV, "SIGSEGV", sig_segv_codes, "Segmentation Fault" },
 180     { SIGBUS,  "SIGBUS",  sig_bus_codes,  "Bus error (bad memory access)" },
 181     { SIGABRT, "SIGABRT", NULL,           "Abort" },
 182 };
 183
 184 /* ucontext is required for non-generic stack backtrace */
 185 #if !defined(USE_UCONTEXT) && !defined(SIGINFO_STACK_GENERIC)
 186 # define SIGINFO_STACK_GENERIC
 187 #endif
 188
 189 #if defined(SIGINFO_STACK_GENERIC)
 190
 191 static void dump_stack(ucontext_t * ucontext)
 192 {
 193     size_t i;
 194     void * bt[SIGINFO_MAX_BT_FRAMES];
 195     char ** strings;
 196     size_t sz;
 197
 198     ((void)(ucontext));         /* unreferenced parameter */
 199
 200     siginfo_log("Stack trace (generic):");
 201
 202     sz = backtrace(bt, SIGINFO_MAX_BT_FRAMES);
 203     strings = backtrace_symbols(bt, sz);
 204
 205     for (i = 0; i < sz; i++)
 206     {
 207         siginfo_log("%2zu: %s", i, strings[i]);
 208     }
 209
 210     siginfo_log("End of stack trace");
 211 }
 212
 213 #else  /* #if defined(SIGINFO_STACK_GENERIC) */
 214
 215 #if defined(SIGINFO_CPP_DEMANGLE)
 216 char * __cxa_demangle(const char * __mangled_name, char * __output_buffer, size_t * __length, int * __status);
 217 #endif
 218
 219 static void dump_stack(ucontext_t * ucontext)
 220 {
 221     int frame;
 222     Dl_info dlinfo;
 223     void ** bp;
 224     void * ip;
 225     const char * symname;
 226 #if defined(SIGINFO_CPP_DEMANGLE)
 227     int demangle_status;
 228     char * demangled_name;
 229 #endif
 230
 231     ip = (void *) SIGINFO_REGISTER(ucontext, SIGINFO_IP_REG);
 232     bp = (void **)SIGINFO_REGISTER(ucontext, SIGINFO_BP_REG);
 233
 234     siginfo_log("Stack trace:");
 235
 236     for (frame = 0; bp != NULL && ip != NULL; frame++, ip = bp[1], bp = (void **)bp[0])
 237     {
 238         //siginfo_log("IP=%p BP=%p", ip, bp);
 239         if (dladdr(ip, &dlinfo) == 0)
 240         {
 241             siginfo_log("%2d: [dladdr failed for %p]", frame, ip);
 242             continue;
 243         }
 244
 245         symname = dlinfo.dli_sname;
 246 #if defined(SIGINFO_CPP_DEMANGLE)
 247         demangled_name = __cxa_demangle(symname, NULL, 0, &demangle_status);
 248         if (demangle_status == 0 && demangled_name != NULL)
 249         {
 250             symname = demangled_name;
 251         }
 252 #endif
 253
 254         siginfo_log(
 255             "%2d: 0x" SIGINFO_REGFORMAT " <%s+%d> (%s)",
 256             frame,
 257             (UINT_PTR_TYPE)ip,
 258             symname,
 259             (int)(ip - dlinfo.dli_saddr),
 260             dlinfo.dli_fname);
 261
 262 #if defined(SIGINFO_NO_CPP_DEMANGLE)
 263         free(demangled_name);
 264 #endif
 265
 266         if (dlinfo.dli_sname && strcmp(dlinfo.dli_sname, "main") == 0) break;
 267     }
 268
 269     siginfo_log("End of stack trace");
 270 }
 271
 272 #endif  /* #if defined(SIGINFO_STACK_GENERIC) */
 273
 274 static struct signal_descriptor * lookup_signal_descriptor(int signo)
 275 {
 276     size_t i;
 277
 278     for (i = 0; i < sizeof(signal_descriptors) / sizeof(signal_descriptors[0]); i++)
 279     {
 280         if (signal_descriptors[i].signo == signo)
 281         {
 282             return signal_descriptors + i;
 283         }
 284     }
 285
 286     return NULL;
 287 }
 288
 289 #if defined(USE_UCONTEXT)
 290 static const char * si_code_description_lookup(struct si_code_descriptor * descr_ptr, int si_code)
 291 {
 292     while (descr_ptr->description != NULL)
 293     {
 294         if (descr_ptr->code == si_code)
 295         {
 296             return descr_ptr->description;
 297         }
 298
 299         descr_ptr++;
 300     }
 301
 302     return NULL;
 303 }
 304
 305 static const char * si_code_description(struct signal_descriptor * descr_ptr, int si_code)
 306 {
 307     const char * si_code_str = NULL;
 308
 309     si_code_str = si_code_description_lookup(sig_any_codes, si_code);
 310     if (si_code_str != NULL)
 311     {
 312         return si_code_str;
 313     }
 314
 315     if (descr_ptr != NULL && descr_ptr->codes != NULL)
 316     {
 317         return si_code_description_lookup(descr_ptr->codes, si_code);
 318     }
 319
 320     return "unknown";
 321 }
 322 #endif  /* #if defined(USE_UCONTEXT) */
 323
 324 static void dump_siginfo(int signo, siginfo_t * info)
 325 {
 326     struct signal_descriptor * descr_ptr;
 327
 328     descr_ptr = lookup_signal_descriptor(signo);
 329     if (descr_ptr != NULL)
 330     {
 331         siginfo_log("%s! (%s)", descr_ptr->msg, descr_ptr->descr);
 332     }
 333     else
 334     {
 335         siginfo_log("Unknown bad signal %d caught!", signo);
 336     }
 337
 338 #if defined(USE_UCONTEXT)
 339     siginfo_log("info.si_signo = %d", info->si_signo);
 340     siginfo_log("info.si_errno = %d", info->si_errno);
 341     siginfo_log("info.si_code  = %d (%s)", info->si_code, si_code_description(descr_ptr, info->si_code));
 342     siginfo_log("info.si_addr  = %p", info->si_addr);
 343 #else
 344     (void)info;                 /* unused parameter */
 345 #endif
 346 }
 347
 348 #if defined(USE_UCONTEXT)
 349 #define REGISTER_NAME_CASE(x) case REG_ ## x: return #x
 350 static const char * register_name(size_t i)
 351 {
 352     switch (i)
 353     {
 354 #if defined(REG_EIP)
 355         REGISTER_NAME_CASE(GS);
 356         REGISTER_NAME_CASE(FS);
 357         REGISTER_NAME_CASE(ES);
 358         REGISTER_NAME_CASE(DS);
 359         REGISTER_NAME_CASE(EDI);
 360         REGISTER_NAME_CASE(ESI);
 361         REGISTER_NAME_CASE(EBP);
 362         REGISTER_NAME_CASE(ESP);
 363         REGISTER_NAME_CASE(EBX);
 364         REGISTER_NAME_CASE(EDX);
 365         REGISTER_NAME_CASE(ECX);
 366         REGISTER_NAME_CASE(EAX);
 367         REGISTER_NAME_CASE(TRAPNO);
 368         REGISTER_NAME_CASE(ERR);
 369         REGISTER_NAME_CASE(EIP);
 370         REGISTER_NAME_CASE(CS);
 371         REGISTER_NAME_CASE(EFL);
 372         REGISTER_NAME_CASE(UESP);
 373         REGISTER_NAME_CASE(SS);
 374 #endif
 375     }
 376
 377     return NULL;
 378 }
 379
 380 static void dump_registers(ucontext_t * ucontext)
 381 {
 382     size_t index;
 383     const char * name;
 384     char buffer[64];
 385
 386     for (index = 0; index < NGREG; index++)
 387     {
 388         name = register_name(index);
 389         if (name == NULL)
 390         {
 391             snprintf(buffer, sizeof(buffer), "reg[%02d]", (int)index);
 392             name = buffer;
 393         }
 394
 395         siginfo_log("%6s = 0x" SIGINFO_REGFORMAT, name, (UINT_PTR_TYPE)SIGINFO_REGISTER(ucontext, index));
 396     }
 397 }
 398 #endif  /* #if defined(USE_UCONTEXT) */
 399
 400 static void signal_handler(int signum, siginfo_t * info, void * ptr)
 401 {
 402     dump_siginfo(signum, info);
 403 #if defined(USE_UCONTEXT)
 404     dump_registers(ptr);
 405 #endif
 406     dump_stack(ptr);
 407     exit(-1);
 408 }
 409
 410 #if defined(SIGINFO_AUTO_INIT)
 411 static
 412 #endif
 413 int setup_siginfo(void)
 414 {
 415     struct sigaction action;
 416     size_t i;
 417
 418     memset(&action, 0, sizeof(action));
 419     action.sa_sigaction = signal_handler;
 420 #ifdef SA_SIGINFO
 421     action.sa_flags = SA_SIGINFO;
 422 #endif
 423
 424     for (i = 0; i < sizeof(signal_descriptors)  / sizeof(signal_descriptors[0]); i++)
 425     {
 426         if (sigaction(signal_descriptors[i].signo, &action, NULL) < 0)
 427         {
 428             siginfo_log("sigaction failed for signal %d. errno is %d (%s)", signal_descriptors[i].signo, errno, strerror(errno));
 429             return 0;
 430         }
 431     }
 432
 433     return 1;
 434 }
 435
 436 #if defined(SIGINFO_AUTO_INIT)
 437 static void __attribute((constructor)) init(void)
 438 {
 439     setup_siginfo();
 440 }
 441 #endif
 442
 443 #if defined(SIGINFO_TEST)
 444
 445 void crash_abort(void)
 446 {
 447     abort();
 448 }
 449
 450 void crash_access(void)
 451 {
 452     /* why this doesnt cause FPE? */
 453     *((float *)123) = 1000.0 / 0.0;
 454 }
 455
 456 void crash_call(void)
 457 {
 458     ((void (*)(void))(0xDEADBEEF))();
 459 }
 460
 461 static void (* tests [])(void) =
 462 {
 463     crash_abort,
 464     crash_access,
 465     crash_call,
 466 };
 467
 468 int main(int argc, char ** argv)
 469 {
 470     unsigned int index;
 471
 472     setup_siginfo();
 473
 474     if (argc > 1)
 475     {
 476         index = atoi(argv[1]);
 477         if (index >= sizeof(tests) / sizeof(tests[0]))
 478         {
 479             siginfo_log("invalid index %d, using 0 instead", index);
 480             index = 0;
 481         }
 482     }
 483     else
 484     {
 485         index = 0;
 486     }
 487
 488     tests[index]();
 489
 490     return 0;
 491 }
 492 #endif