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/**
* This source file is used to print out a stack-trace when your program
* segfaults. It is relatively reliable and spot-on accurate.
*
* This code is in the public domain. Use it as you see fit, some credit
* would be appreciated, but is not a prerequisite for usage. Feedback
* on it's use would encourage further development and maintenance.
*
* Author: Jaco Kroon <jaco@kroon.co.za>
*
* Copyright (C) 2005 - 2006 Jaco Kroon
*/
#define _GNU_SOURCE
#include <memory.h>
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <ucontext.h>
#include <dlfcn.h>
#if defined(HAVE_EXECINFO_H)
#include <execinfo.h>
#endif /* #if defined(HAVE_EXECINFO_H) */
#ifndef NO_CPP_DEMANGLE
#include <cxxabi.h>
#endif
#include <syslog.h>
#if defined(REG_RIP)
# define SIGSEGV_STACK_IA64
# define REGFORMAT "%016lx"
#elif defined(REG_EIP)
# define SIGSEGV_STACK_X86
# define REGFORMAT "%08x"
#else
# define SIGSEGV_STACK_GENERIC
# define REGFORMAT "%lx"
#endif
static void signal_segv(int signum, siginfo_t* info, void*ptr) {
size_t i;
#if defined(NGREG)
ucontext_t *ucontext = (ucontext_t*)ptr;
#endif /* #if defined(NGREG) */
#if defined(SIGSEGV_STACK_X86) || defined(SIGSEGV_STACK_IA64)
int f = 0;
Dl_info dlinfo;
void **bp = 0;
void *ip = 0;
#endif
#if defined(HAVE_EXECINFO_H)
void *bt[20];
char **strings;
size_t sz;
#endif /* #if defined(HAVE_EXECINFO_H) */
openlog("memcached", LOG_PID, LOG_LOCAL0);
syslog(LOG_ALERT, "Segmentation Fault!\n");
syslog(LOG_ALERT, "info.si_signo = %d\n", signum);
syslog(LOG_ALERT, "info.si_errno = %d\n", info->si_errno);
syslog(LOG_ALERT, "info.si_code = %d\n", info->si_code);
syslog(LOG_ALERT, "info.si_addr = %p\n", info->si_addr);
#if defined(NGREG)
for(i = 0; i < NGREG; i++)
syslog(LOG_ALERT, "reg[%02lu] = 0x" REGFORMAT "\n", i, ucontext->uc_mcontext.gregs[i]);
#endif /* #if defined(NGREG) */
#if defined(SIGSEGV_STACK_X86) || defined(SIGSEGV_STACK_IA64)
# if defined(SIGSEGV_STACK_IA64)
ip = (void*)ucontext->uc_mcontext.gregs[REG_RIP];
bp = (void**)ucontext->uc_mcontext.gregs[REG_RBP];
# elif defined(SIGSEGV_STACK_X86)
ip = (void*)ucontext->uc_mcontext.gregs[REG_EIP];
bp = (void**)ucontext->uc_mcontext.gregs[REG_EBP];
# endif
syslog(LOG_ALERT, "Stack trace:\n");
while(ip) {
if(!dladdr(ip, &dlinfo))
break;
const char *symname = dlinfo.dli_sname;
#ifndef NO_CPP_DEMANGLE
int status;
char *tmp = __cxa_demangle(symname, NULL, 0, &status);
if(status == 0 && tmp)
symname = tmp;
#endif
syslog(LOG_ALERT, "% 2d: %p <%s+%u> (%s)\n",
++f,
ip,
symname,
(unsigned)(ip - dlinfo.dli_saddr),
dlinfo.dli_fname);
#ifndef NO_CPP_DEMANGLE
if(tmp)
free(tmp);
#endif
if (bp == NULL) {
break;
}
if(dlinfo.dli_sname && !strcmp(dlinfo.dli_sname, "main"))
break;
ip = bp[1];
bp = (void**)bp[0];
}
#endif
syslog(LOG_ALERT, "End of stack trace\n");
closelog();
#if defined(HAVE_EXECINFO_H)
openlog("memcached", LOG_PID, LOG_LOCAL0);
syslog(LOG_ALERT, "Stack trace (non-dedicated):\n");
sz = backtrace(bt, 20);
strings = backtrace_symbols(bt, sz);
for(i = 0; i < sz; ++i)
syslog(LOG_ALERT, "%s\n", strings[i]);
syslog(LOG_ALERT, "End of stack trace (non-dedicated)\n");
closelog();
#endif /* #if defined(HAVE_EXECINFO_H) */
(void) i; /* consume i so we don't get a compiler warning. */
exit (-1);
}
int setup_sigsegv() {
struct sigaction action;
memset(&action, 0, sizeof(action));
action.sa_sigaction = signal_segv;
action.sa_flags = SA_SIGINFO;
if(sigaction(SIGABRT, &action, NULL) < 0) {
perror("sigaction");
return 0;
}
if(sigaction(SIGBUS, &action, NULL) < 0) {
perror("sigaction");
return 0;
}
if(sigaction(SIGFPE, &action, NULL) < 0) {
perror("sigaction");
return 0;
}
if(sigaction(SIGILL, &action, NULL) < 0) {
perror("sigaction");
return 0;
}
if(sigaction(SIGSEGV, &action, NULL) < 0) {
perror("sigaction");
return 0;
}
return 1;
}
#if 0
#ifndef SIGSEGV_NO_AUTO_INIT
static void __attribute((constructor)) init(void) {
setup_sigsegv();
}
#endif
#endif /* #if 0 */