source: trunk/server/lib/util/fault.c

/* 
   Unix SMB/CIFS implementation.
   Critical Fault handling
   Copyright (C) Andrew Tridgell 1992-1998
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "version.h"
#include "system/wait.h"
#include "system/filesys.h"

/**
 * @file
 * @brief Fault handling
 */

/* the registered fault handler */
static struct {
        const char *name;
        void (*fault_handler)(int sig);
} fault_handlers;

static const char *progname;

#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#elif HAVE_LIBEXC_H
#include <libexc.h>
#endif

/**
 * Write backtrace to debug log
 */
_PUBLIC_ void call_backtrace(void)
{
#ifdef HAVE_BACKTRACE
#ifndef BACKTRACE_STACK_SIZE
#define BACKTRACE_STACK_SIZE 64
#endif
        void *backtrace_stack[BACKTRACE_STACK_SIZE];
        int backtrace_size;
        char **backtrace_strings;

        /* get the backtrace (stack frames) */
        backtrace_size = backtrace(backtrace_stack,BACKTRACE_STACK_SIZE);
        backtrace_strings = backtrace_symbols(backtrace_stack, backtrace_size);

        DEBUG(0, ("BACKTRACE: %lu stack frames:\n", 
                  (unsigned long)backtrace_size));
        
        if (backtrace_strings) {
                int i;

                for (i = 0; i < backtrace_size; i++)
                        DEBUGADD(0, (" #%u %s\n", i, backtrace_strings[i]));

                /* Leak the backtrace_strings, rather than risk what free() might do */
        }

#elif HAVE_LIBEXC

#define NAMESIZE 32 /* Arbitrary */
#ifndef BACKTRACE_STACK_SIZE
#define BACKTRACE_STACK_SIZE 64
#endif

        /* The IRIX libexc library provides an API for unwinding the stack. See
         * libexc(3) for details. Apparantly trace_back_stack leaks memory, but
         * since we are about to abort anyway, it hardly matters.
         *
         * Note that if we paniced due to a SIGSEGV or SIGBUS (or similar) this
         * will fail with a nasty message upon failing to open the /proc entry.
         */
        {
                uint64_t        addrs[BACKTRACE_STACK_SIZE];
                char *          names[BACKTRACE_STACK_SIZE];
                char            namebuf[BACKTRACE_STACK_SIZE * NAMESIZE];

                int             i;
                int             levels;

                ZERO_ARRAY(addrs);
                ZERO_ARRAY(names);
                ZERO_ARRAY(namebuf);

                for (i = 0; i < BACKTRACE_STACK_SIZE; i++) {
                        names[i] = namebuf + (i * NAMESIZE);
                }

                levels = trace_back_stack(0, addrs, names,
                                BACKTRACE_STACK_SIZE, NAMESIZE);

                DEBUG(0, ("BACKTRACE: %d stack frames:\n", levels));
                for (i = 0; i < levels; i++) {
                        DEBUGADD(0, (" #%d 0x%llx %s\n", i, addrs[i], names[i]));
                }
     }
#undef NAMESIZE
#endif
}

_PUBLIC_ const char *panic_action = NULL;

/**
 Something really nasty happened - panic !
**/
_PUBLIC_ _NORETURN_ void smb_panic(const char *why)
{
        int result;

        if (panic_action && *panic_action) {
                char pidstr[20];
                char cmdstring[200];
                safe_strcpy(cmdstring, panic_action, sizeof(cmdstring));
                snprintf(pidstr, sizeof(pidstr), "%d", (int) getpid());
                all_string_sub(cmdstring, "%PID%", pidstr, sizeof(cmdstring));
                if (progname) {
                        all_string_sub(cmdstring, "%PROG%", progname, sizeof(cmdstring));
                }
                DEBUG(0, ("smb_panic(): calling panic action [%s]\n", cmdstring));
                result = system(cmdstring);

                if (result == -1)
                        DEBUG(0, ("smb_panic(): fork failed in panic action: %s\n",
                                  strerror(errno)));
                else
                        DEBUG(0, ("smb_panic(): action returned status %d\n",
                                  WEXITSTATUS(result)));
        }
        DEBUG(0,("PANIC: %s\n", why));

        call_backtrace();

#ifdef SIGABRT
        CatchSignal(SIGABRT, SIG_DFL);
#endif
        abort();
}

/**
report a fault
**/
_NORETURN_ static void fault_report(int sig)
{
        static int counter;
        
        if (counter) _exit(1);

        DEBUG(0,("=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n"));
        DEBUG(0,("INTERNAL ERROR: Signal %d in pid %d (%s)",sig,(int)getpid(),SAMBA_VERSION_STRING));
        DEBUG(0,("\nPlease read the file BUGS.txt in the distribution\n"));
        DEBUG(0,("=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n"));

        smb_panic("internal error");

        exit(1);
}

/**
catch serious errors
**/
_NORETURN_ static void sig_fault(int sig)
{
        if (fault_handlers.fault_handler) {
                /* we have a fault handler, call it. It may not return. */
                fault_handlers.fault_handler(sig);
        }
        /* If it returns or doesn't exist, use regular reporter */
        fault_report(sig);
}

/**
setup our fault handlers
**/
_PUBLIC_ void fault_setup(const char *pname)
{
        if (progname != NULL) {
                return;
        }
        progname = pname;
#ifdef SIGSEGV
        CatchSignal(SIGSEGV, sig_fault);
#endif
#ifdef SIGBUS
        CatchSignal(SIGBUS, sig_fault);
#endif
#ifdef SIGABRT
        CatchSignal(SIGABRT, sig_fault);
#endif
#ifdef SIGFPE
        CatchSignal(SIGFPE, sig_fault);
#endif
}

/**
   disable setting up fault handlers
**/
_PUBLIC_ void fault_setup_disable(void)
{
        progname = "fault disabled";
}


/**
  register a fault handler. 
  Should only be called once in the execution of smbd.
*/
_PUBLIC_ bool register_fault_handler(const char *name, 
                                     void (*fault_handler)(int sig))
{
        if (fault_handlers.name != NULL) {
                /* it's already registered! */
                DEBUG(2,("fault handler '%s' already registered - failed '%s'\n", 
                         fault_handlers.name, name));
                return false;
        }

        fault_handlers.name = name;
        fault_handlers.fault_handler = fault_handler;

        DEBUG(2,("fault handler '%s' registered\n", name));
        return true;
}