about summary refs log tree commit diff
path: root/malloc/mtrace.c
blob: 91e5710468a48cc44e9f526b2b648e36d2439990 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
/* More debugging hooks for `malloc'.
   Copyright (C) 1991-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
                 Written April 2, 1991 by John Gilmore of Cygnus Support.
                 Based on mcheck.c by Mike Haertel.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _MALLOC_INTERNAL
# define _MALLOC_INTERNAL
# include <malloc.h>
# include <mcheck.h>
# include <bits/libc-lock.h>
#endif

#include <dlfcn.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <_itoa.h>

#include <libc-internal.h>

#include <libio/iolibio.h>
#define setvbuf(s, b, f, l) _IO_setvbuf (s, b, f, l)
#define fwrite(buf, size, count, fp) _IO_fwrite (buf, size, count, fp)

#include <kernel-features.h>

#define TRACE_BUFFER_SIZE 512

static FILE *mallstream;
static const char mallenv[] = "MALLOC_TRACE";
static char *malloc_trace_buffer;

__libc_lock_define_initialized (static, lock);

/* Address to breakpoint on accesses to... */
__ptr_t mallwatch;

/* Old hook values.  */
static void (*tr_old_free_hook) (__ptr_t ptr, const __ptr_t);
static __ptr_t (*tr_old_malloc_hook) (size_t size, const __ptr_t);
static __ptr_t (*tr_old_realloc_hook) (__ptr_t ptr, size_t size,
                                       const __ptr_t);
static __ptr_t (*tr_old_memalign_hook) (size_t __alignment, size_t __size,
                                        const __ptr_t);

/* This function is called when the block being alloc'd, realloc'd, or
   freed has an address matching the variable "mallwatch".  In a debugger,
   set "mallwatch" to the address of interest, then put a breakpoint on
   tr_break.  */

extern void tr_break (void) __THROW;
libc_hidden_proto (tr_break)
void
tr_break (void)
{
}
libc_hidden_def (tr_break)

static void internal_function
tr_where (const __ptr_t caller, Dl_info *info)
{
  if (caller != NULL)
    {
      if (info != NULL)
        {
          char *buf = (char *) "";
          if (info->dli_sname != NULL)
            {
              size_t len = strlen (info->dli_sname);
              buf = alloca (len + 6 + 2 * sizeof (void *));

              buf[0] = '(';
              __stpcpy (_fitoa (caller >= (const __ptr_t) info->dli_saddr
                                ? caller - (const __ptr_t) info->dli_saddr
                                : (const __ptr_t) info->dli_saddr - caller,
                                __stpcpy (__mempcpy (buf + 1, info->dli_sname,
                                                     len),
                                          caller >= (__ptr_t) info->dli_saddr
                                          ? "+0x" : "-0x"),
                                16, 0),
                        ")");
            }

          fprintf (mallstream, "@ %s%s%s[%p] ",
                   info->dli_fname ? : "", info->dli_fname ? ":" : "",
                   buf, caller);
        }
      else
        fprintf (mallstream, "@ [%p] ", caller);
    }
}

static Dl_info *
lock_and_info (const __ptr_t caller, Dl_info *mem)
{
  if (caller == NULL)
    return NULL;

  Dl_info *res = _dl_addr (caller, mem, NULL, NULL) ? mem : NULL;

  __libc_lock_lock (lock);

  return res;
}

static void
tr_freehook (__ptr_t ptr, const __ptr_t caller)
{
  if (ptr == NULL)
    return;

  Dl_info mem;
  Dl_info *info = lock_and_info (caller, &mem);
  tr_where (caller, info);
  /* Be sure to print it first.  */
  fprintf (mallstream, "- %p\n", ptr);
  if (ptr == mallwatch)
    {
      __libc_lock_unlock (lock);
      tr_break ();
      __libc_lock_lock (lock);
    }
  __free_hook = tr_old_free_hook;
  if (tr_old_free_hook != NULL)
    (*tr_old_free_hook)(ptr, caller);
  else
    free (ptr);
  __free_hook = tr_freehook;
  __libc_lock_unlock (lock);
}

static __ptr_t
tr_mallochook (size_t size, const __ptr_t caller)
{
  __ptr_t hdr;

  Dl_info mem;
  Dl_info *info = lock_and_info (caller, &mem);

  __malloc_hook = tr_old_malloc_hook;
  if (tr_old_malloc_hook != NULL)
    hdr = (__ptr_t) (*tr_old_malloc_hook)(size, caller);
  else
    hdr = (__ptr_t) malloc (size);
  __malloc_hook = tr_mallochook;

  tr_where (caller, info);
  /* We could be printing a NULL here; that's OK.  */
  fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);

  __libc_lock_unlock (lock);

  if (hdr == mallwatch)
    tr_break ();

  return hdr;
}

static __ptr_t
tr_reallochook (__ptr_t ptr, size_t size, const __ptr_t caller)
{
  __ptr_t hdr;

  if (ptr == mallwatch)
    tr_break ();

  Dl_info mem;
  Dl_info *info = lock_and_info (caller, &mem);

  __free_hook = tr_old_free_hook;
  __malloc_hook = tr_old_malloc_hook;
  __realloc_hook = tr_old_realloc_hook;
  if (tr_old_realloc_hook != NULL)
    hdr = (__ptr_t) (*tr_old_realloc_hook)(ptr, size, caller);
  else
    hdr = (__ptr_t) realloc (ptr, size);
  __free_hook = tr_freehook;
  __malloc_hook = tr_mallochook;
  __realloc_hook = tr_reallochook;

  tr_where (caller, info);
  if (hdr == NULL)
    {
      if (size != 0)
        /* Failed realloc.  */
        fprintf (mallstream, "! %p %#lx\n", ptr, (unsigned long int) size);
      else
        fprintf (mallstream, "- %p\n", ptr);
    }
  else if (ptr == NULL)
    fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
  else
    {
      fprintf (mallstream, "< %p\n", ptr);
      tr_where (caller, info);
      fprintf (mallstream, "> %p %#lx\n", hdr, (unsigned long int) size);
    }

  __libc_lock_unlock (lock);

  if (hdr == mallwatch)
    tr_break ();

  return hdr;
}

static __ptr_t
tr_memalignhook (size_t alignment, size_t size, const __ptr_t caller)
{
  __ptr_t hdr;

  Dl_info mem;
  Dl_info *info = lock_and_info (caller, &mem);

  __memalign_hook = tr_old_memalign_hook;
  __malloc_hook = tr_old_malloc_hook;
  if (tr_old_memalign_hook != NULL)
    hdr = (__ptr_t) (*tr_old_memalign_hook)(alignment, size, caller);
  else
    hdr = (__ptr_t) memalign (alignment, size);
  __memalign_hook = tr_memalignhook;
  __malloc_hook = tr_mallochook;

  tr_where (caller, info);
  /* We could be printing a NULL here; that's OK.  */
  fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);

  __libc_lock_unlock (lock);

  if (hdr == mallwatch)
    tr_break ();

  return hdr;
}


#ifdef _LIBC

/* This function gets called to make sure all memory the library
   allocates get freed and so does not irritate the user when studying
   the mtrace output.  */
static void __libc_freeres_fn_section
release_libc_mem (void)
{
  /* Only call the free function if we still are running in mtrace mode.  */
  if (mallstream != NULL)
    __libc_freeres ();
}
#endif


/* We enable tracing if either the environment variable MALLOC_TRACE
   is set, or if the variable mallwatch has been patched to an address
   that the debugging user wants us to stop on.  When patching mallwatch,
   don't forget to set a breakpoint on tr_break!  */

void
mtrace (void)
{
#ifdef _LIBC
  static int added_atexit_handler;
#endif
  char *mallfile;

  /* Don't panic if we're called more than once.  */
  if (mallstream != NULL)
    return;

#ifdef _LIBC
  /* When compiling the GNU libc we use the secure getenv function
     which prevents the misuse in case of SUID or SGID enabled
     programs.  */
  mallfile = __libc_secure_getenv (mallenv);
#else
  mallfile = getenv (mallenv);
#endif
  if (mallfile != NULL || mallwatch != NULL)
    {
      char *mtb = malloc (TRACE_BUFFER_SIZE);
      if (mtb == NULL)
        return;

      mallstream = fopen (mallfile != NULL ? mallfile : "/dev/null", "wce");
      if (mallstream != NULL)
        {
#ifndef __ASSUME_O_CLOEXEC
          /* Make sure we close the file descriptor on exec.  */
          int flags = __fcntl (fileno (mallstream), F_GETFD, 0);
          if (flags >= 0)
            {
              flags |= FD_CLOEXEC;
              __fcntl (fileno (mallstream), F_SETFD, flags);
            }
#endif
          /* Be sure it doesn't malloc its buffer!  */
          malloc_trace_buffer = mtb;
          setvbuf (mallstream, malloc_trace_buffer, _IOFBF, TRACE_BUFFER_SIZE);
          fprintf (mallstream, "= Start\n");
          tr_old_free_hook = __free_hook;
          __free_hook = tr_freehook;
          tr_old_malloc_hook = __malloc_hook;
          __malloc_hook = tr_mallochook;
          tr_old_realloc_hook = __realloc_hook;
          __realloc_hook = tr_reallochook;
          tr_old_memalign_hook = __memalign_hook;
          __memalign_hook = tr_memalignhook;
#ifdef _LIBC
          if (!added_atexit_handler)
            {
              extern void *__dso_handle __attribute__ ((__weak__));
              added_atexit_handler = 1;
              __cxa_atexit ((void (*)(void *))release_libc_mem, NULL,
                            &__dso_handle ? __dso_handle : NULL);
            }
#endif
        }
      else
        free (mtb);
    }
}

void
muntrace (void)
{
  if (mallstream == NULL)
    return;

  /* Do the reverse of what done in mtrace: first reset the hooks and
     MALLSTREAM, and only after that write the trailer and close the
     file.  */
  FILE *f = mallstream;
  mallstream = NULL;
  __free_hook = tr_old_free_hook;
  __malloc_hook = tr_old_malloc_hook;
  __realloc_hook = tr_old_realloc_hook;
  __memalign_hook = tr_old_memalign_hook;

  fprintf (f, "= End\n");
  fclose (f);
}