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-rw-r--r--lib/util/talloc_stack.c130
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diff --git a/lib/util/talloc_stack.c b/lib/util/talloc_stack.c
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+/*
+ Unix SMB/CIFS implementation.
+ Implement a stack of talloc contexts
+ Copyright (C) Volker Lendecke 2007
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/*
+ * Implement a stack of talloc frames.
+ *
+ * When a new talloc stackframe is allocated with talloc_stackframe(), then
+ * the TALLOC_CTX returned with talloc_tos() is reset to that new
+ * frame. Whenever that stack frame is TALLOC_FREE()'ed, then the reverse
+ * happens: The previous talloc_tos() is restored.
+ *
+ * This API is designed to be robust in the sense that if someone forgets to
+ * TALLOC_FREE() a stackframe, then the next outer one correctly cleans up and
+ * resets the talloc_tos().
+ *
+ * This robustness feature means that we can't rely on a linked list with
+ * talloc destructors because in a hierarchy of talloc destructors the parent
+ * destructor is called before its children destructors. The child destructor
+ * called after the parent would set the talloc_tos() to the wrong value.
+ */
+
+#include "includes.h"
+
+static int talloc_stacksize;
+static int talloc_stack_arraysize;
+static TALLOC_CTX **talloc_stack;
+
+static int talloc_pop(TALLOC_CTX *frame)
+{
+ int i;
+
+ for (i=talloc_stacksize-1; i>0; i--) {
+ if (frame == talloc_stack[i]) {
+ break;
+ }
+ talloc_free(talloc_stack[i]);
+ }
+
+ talloc_stacksize = i;
+ return 0;
+}
+
+/*
+ * Create a new talloc stack frame.
+ *
+ * When free'd, it frees all stack frames that were created after this one and
+ * not explicitly freed.
+ */
+
+static TALLOC_CTX *talloc_stackframe_internal(size_t poolsize)
+{
+ TALLOC_CTX **tmp, *top, *parent;
+
+ if (talloc_stack_arraysize < talloc_stacksize + 1) {
+ tmp = TALLOC_REALLOC_ARRAY(NULL, talloc_stack, TALLOC_CTX *,
+ talloc_stacksize + 1);
+ if (tmp == NULL) {
+ goto fail;
+ }
+ talloc_stack = tmp;
+ talloc_stack_arraysize = talloc_stacksize + 1;
+ }
+
+ if (talloc_stacksize == 0) {
+ parent = talloc_stack;
+ }
+ else {
+ parent = talloc_stack[talloc_stacksize-1];
+ }
+
+ if (poolsize) {
+ top = talloc_pool(parent, poolsize);
+ } else {
+ top = talloc_new(parent);
+ }
+
+ if (top == NULL) {
+ goto fail;
+ }
+
+ talloc_set_destructor(top, talloc_pop);
+
+ talloc_stack[talloc_stacksize++] = top;
+ return top;
+
+ fail:
+ smb_panic("talloc_stackframe failed");
+ return NULL;
+}
+
+TALLOC_CTX *talloc_stackframe(void)
+{
+ return talloc_stackframe_internal(0);
+}
+
+TALLOC_CTX *talloc_stackframe_pool(size_t poolsize)
+{
+ return talloc_stackframe_internal(poolsize);
+}
+
+/*
+ * Get us the current top of the talloc stack.
+ */
+
+TALLOC_CTX *talloc_tos(void)
+{
+ if (talloc_stacksize == 0) {
+ talloc_stackframe();
+ DEBUG(0, ("no talloc stackframe around, leaking memory\n"));
+ }
+
+ return talloc_stack[talloc_stacksize-1];
+}