1/*
2
3  Copyright (C) 2000,2004 Silicon Graphics, Inc.  All Rights Reserved.
4  Portions Copyright 2002-2010 Sun Microsystems, Inc. All rights reserved.
5
6  This program is free software; you can redistribute it and/or modify it
7  under the terms of version 2.1 of the GNU Lesser General Public License
8  as published by the Free Software Foundation.
9
10  This program is distributed in the hope that it would be useful, but
11  WITHOUT ANY WARRANTY; without even the implied warranty of
12  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
13
14  Further, this software is distributed without any warranty that it is
15  free of the rightful claim of any third person regarding infringement
16  or the like.  Any license provided herein, whether implied or
17  otherwise, applies only to this software file.  Patent licenses, if
18  any, provided herein do not apply to combinations of this program with
19  other software, or any other product whatsoever.
20
21  You should have received a copy of the GNU Lesser General Public
22  License along with this program; if not, write the Free Software
23  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston MA 02110-1301,
24  USA.
25
26  Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
27  Mountain View, CA 94043, or:
28
29  http://www.sgi.com
30
31  For further information regarding this notice, see:
32
33  http://oss.sgi.com/projects/GenInfo/NoticeExplan
34
35*/
36
37
38
39#include "config.h"
40#include "pro_incl.h"
41#ifdef HAVE_STDLIB_H
42#include <stdlib.h>
43#endif /* HAVE_STDLIB_H */
44#ifdef HAVE_STRING_H
45#include <string.h>
46#endif /* HAVE_STRING_H */
47#include <malloc.h>
48
49/*
50 When each block is allocated, there is a two-word structure
51 allocated at the beginning so the block can go on a list.
52 The address returned is the address *after* the two pointers
53 at the start.  But this allows us to be given a pointer to
54 a generic block, and go backwards to find the list-node.  Then
55 we can remove this block from it's list without the need to search
56 through a linked list in order to remove the node.  It also allows
57 us to 'delete' a memory block without needing the dbg structure.
58 We still need the dbg structure on allocation so that we know which
59 linked list to add the block to.
60
61 Only the allocation of the dbg structure itself cannot use _dwarf_p_get_alloc.
62 That structure should be set up by hand, and the two list pointers
63 should be initialized to point at the node itself.  That initializes
64 the doubly linked list.
65*/
66
67#define LIST_TO_BLOCK(lst) ((void*) (((char *)lst) + sizeof(memory_list_t)))
68#define BLOCK_TO_LIST(blk) ((memory_list_t*) (((char*)blk) - sizeof(memory_list_t)))
69
70
71/*
72  dbg should be NULL only when allocating dbg itself.  In that
73  case we initialize it to an empty circular doubly-linked list.
74*/
75
76Dwarf_Ptr
77_dwarf_p_get_alloc(Dwarf_P_Debug dbg, Dwarf_Unsigned size)
78{
79    void *sp;
80    memory_list_t *lp = NULL;
81    memory_list_t *dbglp = NULL;
82    memory_list_t *nextblock = NULL;
83
84    /* alloc control struct and data block together for performance reasons */
85    lp = (memory_list_t *) malloc(size + sizeof(memory_list_t));
86    if (lp == NULL) {
87        /* should throw an error */
88        return NULL;
89    }
90
91    /* point to 'size' bytes just beyond lp struct */
92    sp = LIST_TO_BLOCK(lp);
93    memset(sp, 0, size);
94
95    if (dbg == NULL) {
96        lp->next = lp->prev = lp;
97    } else {
98        /* I always have to draw a picture to understand this part. */
99
100        dbglp = BLOCK_TO_LIST(dbg);
101        nextblock = dbglp->next;
102
103        /* Insert between dbglp and nextblock */
104        dbglp->next = lp;
105        lp->prev = dbglp;
106        lp->next = nextblock;
107        nextblock->prev = lp;
108    }
109
110    return sp;
111}
112
113/*
114  This routine is only here in case a caller of an older version of the
115  library is calling this for some reason.
116  We will clean up any stray blocks when the session is closed.
117  No need to remove this block.  In theory the user might be
118  depending on the fact that we used to just 'free' this.
119  In theory they might also be
120  passing a block that they got from libdwarf.  So we don't know if we
121  should try to remove this block from our global list.  Safest just to
122  do nothing at this point.
123
124  !!!
125  This function is deprecated!  Don't call it inside libdwarf or outside of it.
126  !!!
127*/
128
129void
130dwarf_p_dealloc(Dwarf_Small * ptr)
131{
132    return;
133}
134
135/*
136  The dbg structure is not needed here anymore.
137*/
138
139void
140_dwarf_p_dealloc(Dwarf_P_Debug dbg, Dwarf_Small * ptr) /* ARGSUSED */
141{
142  memory_list_t *lp;
143  lp = BLOCK_TO_LIST(ptr);
144
145  /*
146    Remove from a doubly linked, circular list.
147    Read carefully, use a white board if necessary.
148    If this is an empty list, the following statements are no-ops, and
149    will write to the same memory location they read from.
150    This should only happen when we deallocate the dbg structure itself.
151  */
152
153  lp->prev->next = lp->next;
154  lp->next->prev = lp->prev;
155
156  free((void*)lp);
157}
158
159
160/*
161  This routine deallocates all the nodes on the dbg list,
162  and then deallocates the dbg structure itself.
163*/
164
165void
166_dwarf_p_dealloc_all(Dwarf_P_Debug dbg)
167{
168    memory_list_t *dbglp;
169
170    if (dbg == NULL) {
171        /* should throw an error */
172        return;
173    }
174
175    dbglp = BLOCK_TO_LIST(dbg);
176    while (dbglp->next != dbglp) {
177        _dwarf_p_dealloc(dbg, LIST_TO_BLOCK(dbglp->next));
178    }
179    if (dbglp->next != dbglp ||
180        dbglp->prev != dbglp) {
181
182        /* should throw error */
183        /* For some reason we couldn't free all the blocks? */
184        return;
185    }
186    _dwarf_p_dealloc(NULL, (void*)dbg);
187}
188
189