sigsegv.c

   1 /**
   2  * This source file is used to print out a stack-trace when your program
   3  * segfaults.  It is relatively reliable and spot-on accurate.
   4  *
   5  * This code is in the public domain.  Use it as you see fit, some credit
   6  * would be appreciated, but is not a prerequisite for usage.  Feedback
   7  * on it's use would encourage further development and maintenance.
   8  *
   9  * Author:  Jaco Kroon <jaco@kroon.co.za>
  10  *
  11  * Copyright (C) 2005 - 2008 Jaco Kroon
  12  */
  13
  14 #if defined(HAVE_CONFIG_H)
  15 #include "config.h"
  16 #endif
  17
  18 #define NO_CPP_DEMANGLE
  19 #define SIGSEGV_NO_AUTO_INIT
  20
  21 #ifndef _GNU_SOURCE
  22 # define _GNU_SOURCE
  23 #endif
  24
  25 #include <memory.h>
  26 #include <stdlib.h>
  27 #include <stdio.h>
  28 #include <signal.h>
  29 #include <ucontext.h>
  30 #include <dlfcn.h>
  31 #include <execinfo.h>
  32 #include <errno.h>
  33 #ifndef NO_CPP_DEMANGLE
  34 //#include <cxxabi.h>
  35 char * __cxa_demangle(const char * __mangled_name, char * __output_buffer, size_t * __length, int * __status);
  36 #endif
  37
  38 #include <stdbool.h>
  39 #include "log.h"
  40
  41 #if defined(REG_RIP)
  42 # define SIGSEGV_STACK_IA64
  43 # define REGFORMAT "%016lx"
  44 #elif defined(REG_EIP)
  45 # define SIGSEGV_STACK_X86
  46 # define REGFORMAT "%08x"
  47 #else
  48 # define SIGSEGV_STACK_GENERIC
  49 # define REGFORMAT "%x"
  50 #endif
  51
  52 static void signal_segv(int signum, siginfo_t* info, void*ptr) {
  53     static const char *si_codes[3] = {"", "SEGV_MAPERR", "SEGV_ACCERR"};
  54
  55     size_t i;
  56     ucontext_t *ucontext = (ucontext_t*)ptr;
  57
  58 #if defined(SIGSEGV_STACK_X86) || defined(SIGSEGV_STACK_IA64)
  59     int f = 0;
  60     Dl_info dlinfo;
  61     void **bp = 0;
  62     void *ip = 0;
  63 #else
  64     void *bt[20];
  65     char **strings;
  66     size_t sz;
  67 #endif
  68
  69     if (signum == SIGSEGV)
  70     {
  71         a2j_error("Segmentation Fault!");
  72     }
  73     else if (signum == SIGABRT)
  74     {
  75         a2j_error("Abort!");
  76     }
  77     else if (signum == SIGILL)
  78     {
  79         a2j_error("Illegal instruction!");
  80     }
  81     else if (signum == SIGFPE)
  82     {
  83         a2j_error("Floating point exception!");
  84     }
  85     else
  86     {
  87         a2j_error("Unknown bad signal catched!");
  88     }
  89
  90     a2j_error("info.si_signo = %d", signum);
  91     a2j_error("info.si_errno = %d", info->si_errno);
  92     a2j_error("info.si_code  = %d (%s)", info->si_code, si_codes[info->si_code]);
  93     a2j_error("info.si_addr  = %p", info->si_addr);
  94     for(i = 0; i < NGREG; i++)
  95         a2j_error("reg[%02d]       = 0x" REGFORMAT, i, ucontext->uc_mcontext.gregs[i]);
  96
  97 #if defined(SIGSEGV_STACK_X86) || defined(SIGSEGV_STACK_IA64)
  98 # if defined(SIGSEGV_STACK_IA64)
  99     ip = (void*)ucontext->uc_mcontext.gregs[REG_RIP];
 100     bp = (void**)ucontext->uc_mcontext.gregs[REG_RBP];
 101 # elif defined(SIGSEGV_STACK_X86)
 102     ip = (void*)ucontext->uc_mcontext.gregs[REG_EIP];
 103     bp = (void**)ucontext->uc_mcontext.gregs[REG_EBP];
 104 # endif
 105
 106     a2j_error("Stack trace:");
 107     while(bp && ip) {
 108         if(!dladdr(ip, &dlinfo))
 109             break;
 110
 111         const char *symname = dlinfo.dli_sname;
 112 #ifndef NO_CPP_DEMANGLE
 113         int status;
 114         char *tmp = __cxa_demangle(symname, NULL, 0, &status);
 115
 116         if(status == 0 && tmp)
 117             symname = tmp;
 118 #endif
 119
 120         a2j_error("% 2d: %p <%s+%u> (%s)",
 121                 ++f,
 122                 ip,
 123                 symname,
 124                 (unsigned)(ip - dlinfo.dli_saddr),
 125                 dlinfo.dli_fname);
 126
 127 #ifndef NO_CPP_DEMANGLE
 128         if(tmp)
 129             free(tmp);
 130 #endif
 131
 132         if(dlinfo.dli_sname && !strcmp(dlinfo.dli_sname, "main"))
 133             break;
 134
 135         ip = bp[1];
 136         bp = (void**)bp[0];
 137     }
 138 #else
 139     a2j_error("Stack trace (non-dedicated):");
 140     sz = backtrace(bt, 20);
 141     strings = backtrace_symbols(bt, sz);
 142
 143     for(i = 0; i < sz; ++i)
 144         a2j_error("%s", strings[i]);
 145 #endif
 146     a2j_error("End of stack trace");
 147     exit (-1);
 148 }
 149
 150 int setup_sigsegv() {
 151     struct sigaction action;
 152
 153     memset(&action, 0, sizeof(action));
 154     action.sa_sigaction = signal_segv;
 155     action.sa_flags = SA_SIGINFO;
 156     if(sigaction(SIGSEGV, &action, NULL) < 0) {
 157         a2j_error("sigaction failed. errno is %d (%s)", errno, strerror(errno));
 158         return 0;
 159     }
 160
 161     if(sigaction(SIGILL, &action, NULL) < 0) {
 162         a2j_error("sigaction failed. errno is %d (%s)", errno, strerror(errno));
 163         return 0;
 164     }
 165
 166     if(sigaction(SIGABRT, &action, NULL) < 0) {
 167         a2j_error("sigaction failed. errno is %d (%s)", errno, strerror(errno));
 168         return 0;
 169     }
 170
 171     if(sigaction(SIGFPE, &action, NULL) < 0) {
 172         a2j_error("sigaction failed. errno is %d (%s)", errno, strerror(errno));
 173         return 0;
 174     }
 175
 176     return 1;
 177 }
 178
 179 #ifndef SIGSEGV_NO_AUTO_INIT
 180 static void __attribute((constructor)) init(void) {
 181     setup_sigsegv();
 182 }
 183 #endif