2 Unix SMB/CIFS implementation.
3 Implement a stack of talloc contexts
4 Copyright (C) Volker Lendecke 2007
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program 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
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 * Implement a stack of talloc frames.
24 * When a new talloc stackframe is allocated with talloc_stackframe(), then
25 * the TALLOC_CTX returned with talloc_tos() is reset to that new
26 * frame. Whenever that stack frame is TALLOC_FREE()'ed, then the reverse
27 * happens: The previous talloc_tos() is restored.
29 * This API is designed to be robust in the sense that if someone forgets to
30 * TALLOC_FREE() a stackframe, then the next outer one correctly cleans up and
31 * resets the talloc_tos().
33 * This robustness feature means that we can't rely on a linked list with
34 * talloc destructors because in a hierarchy of talloc destructors the parent
35 * destructor is called before its children destructors. The child destructor
36 * called after the parent would set the talloc_tos() to the wrong value.
41 static int talloc_stacksize
;
42 static TALLOC_CTX
**talloc_stack
;
44 static int talloc_pop(TALLOC_CTX
*frame
)
48 for (i
=talloc_stacksize
-1; i
>0; i
--) {
49 if (frame
== talloc_stack
[i
]) {
52 talloc_free(talloc_stack
[i
]);
60 * Create a new talloc stack frame.
62 * When free'd, it frees all stack frames that were created after this one and
63 * not explicitly freed.
66 TALLOC_CTX
*talloc_stackframe(void)
68 TALLOC_CTX
**tmp
, *top
;
70 if (!(tmp
= TALLOC_REALLOC_ARRAY(NULL
, talloc_stack
, TALLOC_CTX
*,
71 talloc_stacksize
+ 1))) {
77 if (!(top
= talloc_new(talloc_stack
))) {
81 talloc_set_destructor(top
, talloc_pop
);
83 talloc_stack
[talloc_stacksize
++] = top
;
88 smb_panic("talloc_stackframe failed");
93 * Get us the current top of the talloc stack.
96 TALLOC_CTX
*talloc_tos(void)
98 if (talloc_stacksize
== 0) {
100 DEBUG(0, ("no talloc stackframe around, leaking memory\n"));
103 return talloc_stack
[talloc_stacksize
-1];