1/* More debugging hooks for `malloc'.
2   Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
3		 Written April 2, 1991 by John Gilmore of Cygnus Support.
4		 Based on mcheck.c by Mike Haertel.
5
6This library is free software; you can redistribute it and/or
7modify it under the terms of the GNU Library General Public License as
8published by the Free Software Foundation; either version 2 of the
9License, or (at your option) any later version.
10
11This library is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14Library General Public License for more details.
15
16You should have received a copy of the GNU Library General Public
17License along with this library; see the file COPYING.LIB.  If
18not, write to the Free Software Foundation, Inc., 675 Mass Ave,
19Cambridge, MA 02139, 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#endif
28
29#include <stdio.h>
30
31#ifndef	__GNU_LIBRARY__
32extern char *getenv ();
33#else
34#include <stdlib.h>
35#endif
36
37static FILE *mallstream;
38static char mallenv[]= "MALLOC_TRACE";
39static char mallbuf[BUFSIZ];	/* Buffer for the output.  */
40
41/* Address to breakpoint on accesses to... */
42__ptr_t mallwatch;
43
44/* Old hook values.  */
45static void (*tr_old_free_hook) __P ((__ptr_t ptr));
46static __ptr_t (*tr_old_malloc_hook) __P ((size_t size));
47static __ptr_t (*tr_old_realloc_hook) __P ((__ptr_t ptr, size_t size));
48
49/* This function is called when the block being alloc'd, realloc'd, or
50   freed has an address matching the variable "mallwatch".  In a debugger,
51   set "mallwatch" to the address of interest, then put a breakpoint on
52   tr_break.  */
53
54void tr_break __P ((void));
55void
56tr_break ()
57{
58}
59
60static void tr_freehook __P ((__ptr_t));
61static void
62tr_freehook (ptr)
63     __ptr_t ptr;
64{
65  fprintf (mallstream, "- %p\n", ptr);	/* Be sure to print it first.  */
66  if (ptr == mallwatch)
67    tr_break ();
68  __free_hook = tr_old_free_hook;
69  free (ptr);
70  __free_hook = tr_freehook;
71}
72
73static __ptr_t tr_mallochook __P ((size_t));
74static __ptr_t
75tr_mallochook(size_t size)
76{
77  __ptr_t hdr;
78
79  __malloc_hook = tr_old_malloc_hook;
80  hdr = (__ptr_t) malloc (size);
81  __malloc_hook = tr_mallochook;
82
83  /* We could be printing a NULL here; that's OK.  */
84  fprintf (mallstream, "+ %p %zx\n", hdr, size);
85
86  if (hdr == mallwatch)
87    tr_break ();
88
89  return hdr;
90}
91
92static __ptr_t tr_reallochook __P ((__ptr_t, size_t));
93static __ptr_t
94tr_reallochook (__ptr_t ptr, size_t size)
95{
96  __ptr_t hdr;
97
98  if (ptr == mallwatch)
99    tr_break ();
100
101  __free_hook = tr_old_free_hook;
102  __malloc_hook = tr_old_malloc_hook;
103  __realloc_hook = tr_old_realloc_hook;
104  hdr = (__ptr_t) realloc (ptr, size);
105  __free_hook = tr_freehook;
106  __malloc_hook = tr_mallochook;
107  __realloc_hook = tr_reallochook;
108  if (hdr == NULL)
109    /* Failed realloc.  */
110    fprintf (mallstream, "! %p %zx\n", ptr, size);
111  else
112    fprintf (mallstream, "< %p\n> %p %zx\n", ptr, hdr, size);
113
114  if (hdr == mallwatch)
115    tr_break ();
116
117  return hdr;
118}
119
120/* We enable tracing if either the environment variable MALLOC_TRACE
121   is set, or if the variable mallwatch has been patched to an address
122   that the debugging user wants us to stop on.  When patching mallwatch,
123   don't forget to set a breakpoint on tr_break!  */
124
125void
126mtrace ()
127{
128  char *mallfile;
129
130  mallfile = getenv (mallenv);
131  if (mallfile != NULL || mallwatch != NULL)
132    {
133      mallstream = fopen (mallfile != NULL ? mallfile : "/dev/null", "w");
134      if (mallstream != NULL)
135	{
136	  /* Be sure it doesn't malloc its buffer!  */
137	  setbuf (mallstream, mallbuf);
138	  fprintf (mallstream, "= Start\n");
139	  tr_old_free_hook = __free_hook;
140	  __free_hook = tr_freehook;
141	  tr_old_malloc_hook = __malloc_hook;
142	  __malloc_hook = tr_mallochook;
143	  tr_old_realloc_hook = __realloc_hook;
144	  __realloc_hook = tr_reallochook;
145	}
146    }
147}
148