lib/util/fault.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Critical Fault handling
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Tim Prouty 2009
   6    Copyright (C) James Peach 2006
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "replace.h"
  23 #include "system/filesys.h"
  24 #include "system/wait.h"
  25 #include "version.h"
  26
  27 #ifdef HAVE_SYS_SYSCTL_H
  28 #include <sys/sysctl.h>
  29 #endif
  30
  31
  32 #ifdef HAVE_SYS_PRCTL_H
  33 #include <sys/prctl.h>
  34 #endif
  35
  36 #include "debug.h"
  37 #include "lib/util/signal.h" /* Avoid /usr/include/signal.h */
  38 #include "substitute.h"
  39 #include "fault.h"
  40
  41 static struct {
  42         bool disabled;
  43         smb_panic_handler_t panic_handler;
  44 } fault_state;
  45
  46
  47 /*******************************************************************
  48 setup variables used for fault handling
  49 ********************************************************************/
  50 void fault_configure(smb_panic_handler_t panic_handler)
  51 {
  52         fault_state.panic_handler = panic_handler;
  53 }
  54
  55
  56 /**
  57    disable setting up fault handlers
  58    This is used for the bind9 dlz module, as we
  59    don't want a Samba module in bind9 to override the bind
  60    fault handling
  61 **/
  62 _PUBLIC_ void fault_setup_disable(void)
  63 {
  64         fault_state.disabled = true;
  65 }
  66
  67
  68 /*******************************************************************
  69 report a fault
  70 ********************************************************************/
  71 static void fault_report(int sig)
  72 {
  73         static int counter;
  74
  75         if (counter) _exit(1);
  76
  77         counter++;
  78
  79         DEBUGSEP(0);
  80         DEBUG(0,("INTERNAL ERROR: Signal %d in pid %d (%s)",sig,(int)getpid(),SAMBA_VERSION_STRING));
  81         DEBUG(0,("\nPlease read the Trouble-Shooting section of the Samba HOWTO\n"));
  82         DEBUGSEP(0);
  83
  84         smb_panic("internal error");
  85
  86         /* smb_panic() never returns, so this is really redundant */
  87         exit(1);
  88 }
  89
  90 /****************************************************************************
  91 catch serious errors
  92 ****************************************************************************/
  93 static void sig_fault(int sig)
  94 {
  95         fault_report(sig);
  96 }
  97
  98 /*******************************************************************
  99 setup our fault handlers
 100 ********************************************************************/
 101 void fault_setup(void)
 102 {
 103         if (fault_state.disabled) {
 104                 return;
 105         }
 106 #if !defined(HAVE_DISABLE_FAULT_HANDLING)
 107 #ifdef SIGSEGV
 108         CatchSignal(SIGSEGV, sig_fault);
 109 #endif
 110 #ifdef SIGBUS
 111         CatchSignal(SIGBUS, sig_fault);
 112 #endif
 113 #ifdef SIGABRT
 114         CatchSignal(SIGABRT, sig_fault);
 115 #endif
 116 #endif
 117 }
 118
 119 _PUBLIC_ const char *panic_action = NULL;
 120
 121 /*
 122    default smb_panic() implementation
 123 */
 124 static void smb_panic_default(const char *why) _NORETURN_;
 125 static void smb_panic_default(const char *why)
 126 {
 127         DBG_ERR("PANIC (pid %llu): %s\n",
 128                     (unsigned long long)getpid(), why);
 129         log_stack_trace();
 130
 131 #if defined(HAVE_PRCTL) && defined(PR_SET_PTRACER)
 132         /*
 133          * Make sure all children can attach a debugger.
 134          */
 135         prctl(PR_SET_PTRACER, getpid(), 0, 0, 0);
 136 #endif
 137
 138         if (panic_action && *panic_action) {
 139                 char cmdstring[200];
 140                 if (strlcpy(cmdstring, panic_action, sizeof(cmdstring)) < sizeof(cmdstring)) {
 141                         int result;
 142                         char pidstr[20];
 143                         snprintf(pidstr, sizeof(pidstr), "%d", (int) getpid());
 144                         all_string_sub(cmdstring, "%d", pidstr, sizeof(cmdstring));
 145                         DEBUG(0, ("smb_panic(): calling panic action [%s]\n", cmdstring));
 146                         result = system(cmdstring);
 147
 148                         if (result == -1)
 149                                 DEBUG(0, ("smb_panic(): fork failed in panic action: %s\n",
 150                                           strerror(errno)));
 151                         else
 152                                 DEBUG(0, ("smb_panic(): action returned status %d\n",
 153                                           WEXITSTATUS(result)));
 154                 }
 155         }
 156
 157 #ifdef SIGABRT
 158         CatchSignal(SIGABRT, SIG_DFL);
 159 #endif
 160         abort();
 161 }
 162
 163
 164 /**
 165    Something really nasty happened - panic !
 166 **/
 167 _PUBLIC_ void smb_panic(const char *why)
 168 {
 169         if (fault_state.panic_handler) {
 170                 fault_state.panic_handler(why);
 171                 _exit(1);
 172         }
 173         smb_panic_default(why);
 174 }
 175
 176 /*******************************************************************
 177  Print a backtrace of the stack to the debug log. This function
 178  DELIBERATELY LEAKS MEMORY. The expectation is that you should
 179  exit shortly after calling it.
 180 ********************************************************************/
 181
 182 /* Buffer size to use when printing backtraces */
 183 #define BACKTRACE_STACK_SIZE 64
 184
 185
 186 #ifdef HAVE_LIBUNWIND_H
 187 #include <libunwind.h>
 188 #endif
 189
 190 #ifdef HAVE_EXECINFO_H
 191 #include <execinfo.h>
 192 #endif
 193
 194 void log_stack_trace(void)
 195 {
 196 #ifdef HAVE_LIBUNWIND
 197         /* Try to use libunwind before any other technique since on ia64
 198          * libunwind correctly walks the stack in more circumstances than
 199          * backtrace.
 200          */
 201         unw_cursor_t cursor;
 202         unw_context_t uc;
 203         unsigned i = 0;
 204
 205         char procname[256];
 206         unw_word_t ip, sp, off;
 207
 208         procname[sizeof(procname) - 1] = '\0';
 209
 210         if (unw_getcontext(&uc) != 0) {
 211                 goto libunwind_failed;
 212         }
 213
 214         if (unw_init_local(&cursor, &uc) != 0) {
 215                 goto libunwind_failed;
 216         }
 217
 218         DEBUG(0, ("BACKTRACE:\n"));
 219
 220         do {
 221             ip = sp = 0;
 222             unw_get_reg(&cursor, UNW_REG_IP, &ip);
 223             unw_get_reg(&cursor, UNW_REG_SP, &sp);
 224
 225             switch (unw_get_proc_name(&cursor,
 226                         procname, sizeof(procname) - 1, &off) ) {
 227             case 0:
 228                     /* Name found. */
 229             case -UNW_ENOMEM:
 230                     /* Name truncated. */
 231                     DEBUGADD(0, (" #%u %s + %#llx [ip=%#llx] [sp=%#llx]\n",
 232                             i, procname, (long long)off,
 233                             (long long)ip, (long long) sp));
 234                     break;
 235             default:
 236             /* case -UNW_ENOINFO: */
 237             /* case -UNW_EUNSPEC: */
 238                     /* No symbol name found. */
 239                     DEBUGADD(0, (" #%u %s [ip=%#llx] [sp=%#llx]\n",
 240                             i, "<unknown symbol>",
 241                             (long long)ip, (long long) sp));
 242             }
 243             ++i;
 244         } while (unw_step(&cursor) > 0);
 245
 246         return;
 247
 248 libunwind_failed:
 249         DEBUG(0, ("unable to produce a stack trace with libunwind\n"));
 250
 251 #elif defined(HAVE_BACKTRACE_SYMBOLS)
 252         void *backtrace_stack[BACKTRACE_STACK_SIZE];
 253         size_t backtrace_size;
 254         char **backtrace_strings;
 255
 256         /* get the backtrace (stack frames) */
 257         backtrace_size = backtrace(backtrace_stack,BACKTRACE_STACK_SIZE);
 258         backtrace_strings = backtrace_symbols(backtrace_stack, backtrace_size);
 259
 260         DEBUG(0, ("BACKTRACE: %lu stack frames:\n",
 261                   (unsigned long)backtrace_size));
 262
 263         if (backtrace_strings) {
 264                 int i;
 265
 266                 for (i = 0; i < backtrace_size; i++)
 267                         DEBUGADD(0, (" #%u %s\n", i, backtrace_strings[i]));
 268
 269                 /* Leak the backtrace_strings, rather than risk what free() might do */
 270         }
 271
 272 #else
 273         DEBUG(0, ("unable to produce a stack trace on this platform\n"));
 274 #endif
 275 }