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(int *ptr)
49 for (i=talloc_stacksize-1; i>=tos; i--) {
50 talloc_free(talloc_stack[i]);
53 talloc_stacksize = tos;
58 * Create a new talloc stack frame.
60 * When free'd, it frees all stack frames that were created after this one and
61 * not explicitly freed.
64 TALLOC_CTX *talloc_stackframe(void)
66 TALLOC_CTX **tmp, *top;
69 if (!(tmp = TALLOC_REALLOC_ARRAY(NULL, talloc_stack, TALLOC_CTX *,
70 talloc_stacksize + 1))) {
76 if (!(top = talloc_new(talloc_stack))) {
80 if (!(cleanup = talloc(top, int))) {
84 *cleanup = talloc_stacksize;
85 talloc_set_destructor(cleanup, talloc_pop);
87 talloc_stack[talloc_stacksize++] = top;
92 smb_panic("talloc_stackframe failed");
97 * Get us the current top of the talloc stack.
100 TALLOC_CTX *talloc_tos(void)
102 if (talloc_stacksize == 0) {
103 DEBUG(0, ("no talloc stackframe around, leaking memory\n"));
107 return talloc_stack[talloc_stacksize-1];