malloc/mtrace.c

   1 /* More debugging hooks for `malloc'.
   2    Copyright (C) 1991,92,93,94,96,97,98,99 Free Software Foundation, Inc.
   3                  Written April 2, 1991 by John Gilmore of Cygnus Support.
   4                  Based on mcheck.c by Mike Haertel.
   5
   6    This library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    This library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with this library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.
  20
  21    The author may be reached (Email) at the address mike@ai.mit.edu,
  22    or (US mail) as Mike Haertel c/o Free Software Foundation.  */
  23
  24 #ifndef _MALLOC_INTERNAL
  25 #define _MALLOC_INTERNAL
  26 #include <malloc.h>
  27 #include <mcheck.h>
  28 #include <bits/libc-lock.h>
  29 #endif
  30
  31 #include <ldsodefs.h>
  32
  33 #include <stdio.h>
  34 #include <string.h>
  35 #include <stdlib.h>
  36
  37 #include <stdio-common/_itoa.h>
  38
  39 #ifdef USE_IN_LIBIO
  40 # include <libio/iolibio.h>
  41 # define setvbuf(s, b, f, l) _IO_setvbuf (s, b, f, l)
  42 #endif
  43
  44 #define TRACE_BUFFER_SIZE 512
  45
  46 static FILE *mallstream;
  47 static const char mallenv[]= "MALLOC_TRACE";
  48 static char malloc_trace_buffer[TRACE_BUFFER_SIZE];
  49
  50 __libc_lock_define_initialized (static, lock);
  51
  52 /* Address to breakpoint on accesses to... */
  53 __ptr_t mallwatch;
  54
  55 /* File name and line number information, for callers that had
  56    the foresight to call through a macro.  */
  57 char *_mtrace_file;
  58 int _mtrace_line;
  59
  60 /* Old hook values.  */
  61 static void (*tr_old_free_hook) __P ((__ptr_t ptr, const __ptr_t));
  62 static __ptr_t (*tr_old_malloc_hook) __P ((__malloc_size_t size,
  63                                            const __ptr_t));
  64 static __ptr_t (*tr_old_realloc_hook) __P ((__ptr_t ptr,
  65                                             __malloc_size_t size,
  66                                             const __ptr_t));
  67
  68 /* This function is called when the block being alloc'd, realloc'd, or
  69    freed has an address matching the variable "mallwatch".  In a debugger,
  70    set "mallwatch" to the address of interest, then put a breakpoint on
  71    tr_break.  */
  72
  73 void tr_break __P ((void));
  74 void
  75 tr_break ()
  76 {
  77 }
  78
  79 static void tr_where __P ((const __ptr_t)) internal_function;
  80 static void
  81 internal_function
  82 tr_where (caller)
  83      const __ptr_t caller;
  84 {
  85   if (_mtrace_file)
  86     {
  87       fprintf (mallstream, "@ %s:%d ", _mtrace_file, _mtrace_line);
  88       _mtrace_file = NULL;
  89     }
  90   else if (caller != NULL)
  91     {
  92 #ifdef HAVE_ELF
  93       Dl_info info;
  94       if (_dl_addr (caller, &info))
  95         {
  96           char *buf = (char *) "";
  97           if (info.dli_sname && info.dli_sname[0])
  98             {
  99               size_t len = strlen (info.dli_sname);
 100               buf = alloca (len + 6 + 2 * sizeof (void *));
 101
 102               buf[0] = '(';
 103               __stpcpy (_fitoa (caller >= (const __ptr_t) info.dli_saddr
 104                                 ? caller - (const __ptr_t) info.dli_saddr
 105                                 : (const __ptr_t) info.dli_saddr - caller,
 106                                 __stpcpy (__mempcpy (buf + 1, info.dli_sname,
 107                                                      len),
 108                                           caller >= (__ptr_t) info.dli_saddr
 109                                           ? "+0x" : "-0x"),
 110                                 16, 0),
 111                         ")");
 112             }
 113
 114           fprintf (mallstream, "@ %s%s%s[%p] ",
 115                    info.dli_fname ?: "", info.dli_fname ? ":" : "",
 116                    buf, caller);
 117         }
 118       else
 119 #endif
 120         fprintf (mallstream, "@ [%p] ", caller);
 121     }
 122 }
 123
 124 static void tr_freehook __P ((__ptr_t, const __ptr_t));
 125 static void
 126 tr_freehook (ptr, caller)
 127      __ptr_t ptr;
 128      const __ptr_t caller;
 129 {
 130   tr_where (caller);
 131   /* Be sure to print it first.  */
 132   fprintf (mallstream, "- %p\n", ptr);
 133   if (ptr == mallwatch)
 134     tr_break ();
 135   __libc_lock_lock (lock);
 136   __free_hook = tr_old_free_hook;
 137   if (tr_old_free_hook != NULL)
 138     (*tr_old_free_hook) (ptr, caller);
 139   else
 140     free (ptr);
 141   __free_hook = tr_freehook;
 142   __libc_lock_unlock (lock);
 143 }
 144
 145 static __ptr_t tr_mallochook __P ((__malloc_size_t, const __ptr_t));
 146 static __ptr_t
 147 tr_mallochook (size, caller)
 148      __malloc_size_t size;
 149      const __ptr_t caller;
 150 {
 151   __ptr_t hdr;
 152
 153   __libc_lock_lock (lock);
 154
 155   __malloc_hook = tr_old_malloc_hook;
 156   if (tr_old_malloc_hook != NULL)
 157     hdr = (__ptr_t) (*tr_old_malloc_hook) (size, caller);
 158   else
 159     hdr = (__ptr_t) malloc (size);
 160   __malloc_hook = tr_mallochook;
 161
 162   __libc_lock_unlock (lock);
 163
 164   tr_where (caller);
 165   /* We could be printing a NULL here; that's OK.  */
 166   fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
 167
 168   if (hdr == mallwatch)
 169     tr_break ();
 170
 171   return hdr;
 172 }
 173
 174 static __ptr_t tr_reallochook __P ((__ptr_t, __malloc_size_t, const __ptr_t));
 175 static __ptr_t
 176 tr_reallochook (ptr, size, caller)
 177      __ptr_t ptr;
 178      __malloc_size_t size;
 179      const __ptr_t caller;
 180 {
 181   __ptr_t hdr;
 182
 183   if (ptr == mallwatch)
 184     tr_break ();
 185
 186   __libc_lock_lock (lock);
 187
 188   __free_hook = tr_old_free_hook;
 189   __malloc_hook = tr_old_malloc_hook;
 190   __realloc_hook = tr_old_realloc_hook;
 191   if (tr_old_realloc_hook != NULL)
 192     hdr = (__ptr_t) (*tr_old_realloc_hook) (ptr, size, caller);
 193   else
 194     hdr = (__ptr_t) realloc (ptr, size);
 195   __free_hook = tr_freehook;
 196   __malloc_hook = tr_mallochook;
 197   __realloc_hook = tr_reallochook;
 198
 199   __libc_lock_unlock (lock);
 200
 201   tr_where (caller);
 202   if (hdr == NULL)
 203     /* Failed realloc.  */
 204     fprintf (mallstream, "! %p %#lx\n", ptr, (unsigned long int) size);
 205   else if (ptr == NULL)
 206     fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
 207   else
 208     {
 209       fprintf (mallstream, "< %p\n", ptr);
 210       tr_where (caller);
 211       fprintf (mallstream, "> %p %#lx\n", hdr, (unsigned long int) size);
 212     }
 213
 214   if (hdr == mallwatch)
 215     tr_break ();
 216
 217   return hdr;
 218 }
 219
 220
 221 #ifdef _LIBC
 222 extern void __libc_freeres (void);
 223
 224 /* This function gets called to make sure all memory the library
 225    allocates get freed and so does not irritate the user when studying
 226    the mtrace output.  */
 227 static void
 228 release_libc_mem (void)
 229 {
 230   /* Only call the free function if we still are running in mtrace mode.  */
 231   if (mallstream != NULL)
 232     __libc_freeres ();
 233 }
 234 #endif
 235
 236
 237 /* We enable tracing if either the environment variable MALLOC_TRACE
 238    is set, or if the variable mallwatch has been patched to an address
 239    that the debugging user wants us to stop on.  When patching mallwatch,
 240    don't forget to set a breakpoint on tr_break!  */
 241
 242 void
 243 mtrace ()
 244 {
 245 #ifdef _LIBC
 246   static int added_atexit_handler;
 247 #endif
 248   char *mallfile;
 249
 250   /* Don't panic if we're called more than once.  */
 251   if (mallstream != NULL)
 252     return;
 253
 254 #ifdef _LIBC
 255   /* When compiling the GNU libc we use the secure getenv function
 256      which prevents the misuse in case of SUID or SGID enabled
 257      programs.  */
 258   mallfile = __secure_getenv (mallenv);
 259 #else
 260   mallfile = getenv (mallenv);
 261 #endif
 262   if (mallfile != NULL || mallwatch != NULL)
 263     {
 264       mallstream = fopen (mallfile != NULL ? mallfile : "/dev/null", "w");
 265       if (mallstream != NULL)
 266         {
 267           /* Be sure it doesn't malloc its buffer!  */
 268           setvbuf (mallstream, malloc_trace_buffer, _IOFBF, TRACE_BUFFER_SIZE);
 269           fprintf (mallstream, "= Start\n");
 270           tr_old_free_hook = __free_hook;
 271           __free_hook = tr_freehook;
 272           tr_old_malloc_hook = __malloc_hook;
 273           __malloc_hook = tr_mallochook;
 274           tr_old_realloc_hook = __realloc_hook;
 275           __realloc_hook = tr_reallochook;
 276 #ifdef _LIBC
 277           if (!added_atexit_handler)
 278             {
 279               added_atexit_handler = 1;
 280               atexit (release_libc_mem);
 281             }
 282 #endif
 283         }
 284     }
 285 }
 286
 287 void
 288 muntrace ()
 289 {
 290   if (mallstream == NULL)
 291     return;
 292
 293   fprintf (mallstream, "= End\n");
 294   fclose (mallstream);
 295   mallstream = NULL;
 296   __free_hook = tr_old_free_hook;
 297   __malloc_hook = tr_old_malloc_hook;
 298   __realloc_hook = tr_old_realloc_hook;
 299 }