The Tcpdump Group git mirrors - tcpdump/blob - instrument-functions.c

   1 /*
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that: (1) source code
   4  * distributions retain the above copyright notice and this paragraph
   5  * in its entirety, and (2) distributions including binary code include
   6  * the above copyright notice and this paragraph in its entirety in
   7  * the documentation or other materials provided with the distribution.
   8  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
   9  * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
  10  * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  11  * FOR A PARTICULAR PURPOSE.
  12  */
  13
  14 #ifndef _GNU_SOURCE
  15 #define _GNU_SOURCE
  16 #endif
  17
  18 #include <stdio.h>
  19 #include <dlfcn.h>
  20
  21 extern int profile_func_level;
  22 int profile_func_level = -1;
  23
  24 /*
  25  * Generate instrumentation calls for entry and exit to functions.
  26  * Just after function entry and just before function exit, the
  27  * following profiling functions are called with the address of the
  28  * current function and its call site (currently not use).
  29  *
  30  * The attribute 'no_instrument_function' causes this instrumentation is
  31  * not done.
  32  *
  33  * These profiling functions print the function names with indentation
  34  * and call level.
  35  *
  36  * To instument a static function, remove temporarily the static specifier.
  37  */
  38
  39 void __cyg_profile_func_enter(void *this_fn, void *call_site)
  40                               __attribute__((no_instrument_function));
  41
  42 void __cyg_profile_func_exit(void *this_fn, void *call_site)
  43                              __attribute__((no_instrument_function));
  44
  45 /*
  46  * The get_function_name() get the function name by calling dladdr()
  47  */
  48
  49 static const char *get_function_name(void *func)
  50                               __attribute__((no_instrument_function));
  51
  52 static const char *
  53 get_function_name(void *func)
  54 {
  55         Dl_info info;
  56         const char *function_name;
  57
  58         if(dladdr(func, &info))
  59                 function_name = info.dli_sname;
  60         else
  61                 function_name = NULL;
  62         return function_name;
  63 }
  64
  65 void
  66 __cyg_profile_func_enter(void *this_fn,
  67                               void *call_site __attribute__((unused)))
  68 {
  69         int i;
  70         const char *function_name;
  71
  72         if((function_name = get_function_name(this_fn)) != NULL) {
  73                 profile_func_level += 1;
  74                 for (i = 0 ; i < profile_func_level ; i++)
  75                         putchar(' ');
  76                 printf("[>> %s (%d)]\n", function_name, profile_func_level);
  77         }
  78         fflush(stdout);
  79 }
  80
  81 void
  82 __cyg_profile_func_exit(void *this_fn,
  83                              void *call_site __attribute__((unused)))
  84 {
  85         int i;
  86         const char *function_name;
  87
  88         if((function_name = get_function_name(this_fn)) != NULL) {
  89                 for (i = 0 ; i < profile_func_level ; i++)
  90                         putchar(' ');
  91                 printf ("[<< %s (%d)]\n", function_name, profile_func_level);
  92                 profile_func_level -= 1;
  93         }
  94         fflush(stdout);
  95 }