utility/fcbacktrace.c

   1 /**********************************************************************
   2  Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; either version 2, or (at your option)
   6    any later version.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12 ***********************************************************************/
  13
  14 #ifdef HAVE_CONFIG_H
  15 #include <fc_config.h>
  16 #endif /* HAVE_CONFIG_H */
  17
  18 #include "fc_prehdrs.h"
  19
  20 #ifdef HAVE_EXECINFO_H
  21 #include <execinfo.h>
  22 #endif
  23
  24 /* utility */
  25 #include "log.h"
  26 #include "shared.h"
  27
  28 #include "fcbacktrace.h"
  29
  30 /* We don't want backtrace-spam to testmatic logs */
  31 #if defined(DEBUG) && defined(HAVE_BACKTRACE) && !defined(FREECIV_TESTMATIC)
  32 #define BACKTRACE_ACTIVE 1
  33 #endif
  34
  35 #ifdef BACKTRACE_ACTIVE
  36
  37 /* We write always in level LOG_NORMAL and not in higher one since those
  38  * interact badly with server callback to send error messages to local
  39  * client. */
  40 #define LOG_BACKTRACE LOG_NORMAL
  41
  42 #define MAX_NUM_FRAMES 64
  43
  44 static log_pre_callback_fn previous = NULL;
  45
  46 static void write_backtrace_line(enum log_level level, bool print_from_where,
  47                                  const char *where, const char *msg);
  48 static void backtrace_log(enum log_level level, bool print_from_where,
  49                           const char *where, const char *msg);
  50 #endif /* BACKTRACE_ACTIVE */
  51
  52 /************************************************************************
  53   Take backtrace log callback to use
  54 ************************************************************************/
  55 void backtrace_init(void)
  56 {
  57 #ifdef BACKTRACE_ACTIVE
  58   previous = log_set_pre_callback(backtrace_log);
  59 #endif
  60 }
  61
  62 /************************************************************************
  63   Remove backtrace log callback from use
  64 ************************************************************************/
  65 void backtrace_deinit(void)
  66 {
  67 #ifdef BACKTRACE_ACTIVE
  68   log_pre_callback_fn active;
  69
  70   active = log_set_pre_callback(previous);
  71
  72   if (active != backtrace_log) {
  73     /* We were not the active callback!
  74      * Restore the active callback and log error */
  75     log_set_pre_callback(active);
  76     log_error("Backtrace log (pre)callback cannot be removed");
  77   }
  78 #endif /* BACKTRACE_ACTIVE */
  79 }
  80
  81 #ifdef BACKTRACE_ACTIVE
  82 /************************************************************************
  83   Write one line of backtrace
  84 ************************************************************************/
  85 static void write_backtrace_line(enum log_level level, bool print_from_where,
  86                                  const char *where, const char *msg)
  87 {
  88   /* Current behavior of this function is to write to chained callback,
  89    * nothing more, nothing less. */
  90   if (previous != NULL) {
  91     previous(level, print_from_where, where, msg);
  92   }
  93 }
  94
  95 /*****************************************************************************
  96   Main backtrace callback called from logging code.
  97 *****************************************************************************/
  98 static void backtrace_log(enum log_level level, bool print_from_where,
  99                           const char *where, const char *msg)
 100 {
 101   if (previous != NULL) {
 102     /* Call chained callback first */
 103     previous(level, print_from_where, where, msg);
 104   }
 105
 106   if (level <= LOG_ERROR) {
 107     backtrace_print(LOG_BACKTRACE);
 108   }
 109 }
 110
 111 #endif /* BACKTRACE_ACTIVE */
 112
 113 /*****************************************************************************
 114   Print backtrace
 115 *****************************************************************************/
 116 void backtrace_print(enum log_level level)
 117 {
 118 #ifdef BACKTRACE_ACTIVE
 119   void *buffer[MAX_NUM_FRAMES];
 120   int frames;
 121   char **names;
 122
 123   frames = backtrace(buffer, ARRAY_SIZE(buffer));
 124   names = backtrace_symbols(buffer, frames);
 125
 126   if (names == NULL) {
 127     write_backtrace_line(level, FALSE, NULL, "No backtrace");
 128   } else {
 129     int i;
 130
 131     write_backtrace_line(level, FALSE, NULL, "Backtrace:");
 132
 133     for (i = 0; i < MIN(frames, MAX_NUM_FRAMES); i++) {
 134       char linestr[256];
 135
 136       fc_snprintf(linestr, sizeof(linestr), "%5d: %s", i, names[i]);
 137
 138       write_backtrace_line(level, FALSE, NULL, linestr);
 139     }
 140
 141     free(names);
 142   }
 143 #endif /* BACKTRACE_ACTIVE */
 144 }