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// Copyright (c) 2011, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ---
// Author: Rebecca Shapiro <bxx@google.com>
//
// This file contains declarations of functions that implement doubly
// linked lists and definitions of functions that implement singly
// linked lists. It also contains macros to tell the SizeMap class
// how much space a node in the freelist needs so that SizeMap can
// create large enough size classes.
#ifndef TCMALLOC_FREE_LIST_H_
#define TCMALLOC_FREE_LIST_H_
#include <stddef.h>
#include "internal_logging.h"
#include "linked_list.h"
#include "system-alloc.h"
namespace tcmalloc {
#if defined(TCMALLOC_USE_DOUBLYLINKED_FREELIST)
// size class information for common.h.
static const bool kSupportsDoublyLinkedList = true;
void FL_PopRange(void** head, int n, void** start, void** end);
void FL_PushRange(void** head, void* start, void* end);
size_t FL_Size(void* head);
template <typename T>
inline void FL_EqualityCheck(const T& v0,
const T& v1,
const char* file,
int line) {
if (v0 != v1)
Log(kCrash, file, line, "Memory corruption detected.");
}
inline void EnsureNonLoop(void* node, void* next) {
// We only have time to do minimal checking. We don't traverse the list, but
// only look for an immediate loop (cycle back to ourself).
if (node != next)
return;
Log(kCrash, __FILE__, __LINE__, "Circular loop in list detected: ", next);
}
inline void* MaskPtr(void* p) {
// Maximize ASLR entropy and guarantee the result is an invalid address.
const uintptr_t mask =
~(reinterpret_cast<uintptr_t>(TCMalloc_SystemAlloc) >> 13);
return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(p) ^ mask);
}
inline void* UnmaskPtr(void* p) {
return MaskPtr(p);
}
// Returns value of the |previous| pointer w/out running a sanity
// check.
inline void* FL_Previous_No_Check(void* t) {
return UnmaskPtr(reinterpret_cast<void**>(t)[1]);
}
// Returns value of the |next| pointer w/out running a sanity check.
inline void* FL_Next_No_Check(void* t) {
return UnmaskPtr(reinterpret_cast<void**>(t)[0]);
}
inline void* FL_Previous(void* t) {
void* previous = FL_Previous_No_Check(t);
if (previous) {
FL_EqualityCheck(FL_Next_No_Check(previous), t, __FILE__, __LINE__);
}
return previous;
}
inline void FL_SetPrevious(void* t, void* n) {
EnsureNonLoop(t, n);
reinterpret_cast<void**>(t)[1] = MaskPtr(n);
}
inline void FL_SetNext(void* t, void* n) {
EnsureNonLoop(t, n);
reinterpret_cast<void**>(t)[0] = MaskPtr(n);
}
inline void* FL_Next(void* t) {
void* next = FL_Next_No_Check(t);
if (next) {
FL_EqualityCheck(FL_Previous_No_Check(next), t, __FILE__, __LINE__);
}
return next;
}
// Pops the top element off the linked list whose first element is at
// |*list|, and updates |*list| to point to the next element in the
// list. Returns the address of the element that was removed from the
// linked list. |list| must not be NULL.
inline void* FL_Pop(void** list) {
void* result = *list;
ASSERT(FL_Previous_No_Check(result) == NULL);
*list = FL_Next(result);
if (*list != NULL) {
FL_SetPrevious(*list, NULL);
}
return result;
}
// Makes the element at |t| a singleton doubly linked list.
inline void FL_Init(void* t) {
FL_SetPrevious(t, NULL);
FL_SetNext(t, NULL);
}
// Pushes element to a linked list whose first element is at
// |*list|. When this call returns, |list| will point to the new head
// of the linked list.
inline void FL_Push(void** list, void* element) {
void* old = *list;
if (old == NULL) { // Builds singleton list.
FL_Init(element);
} else {
ASSERT(FL_Previous_No_Check(old) == NULL);
FL_SetNext(element, old);
FL_SetPrevious(old, element);
FL_SetPrevious(element, NULL);
}
*list = element;
}
#else // TCMALLOC_USE_DOUBLYLINKED_FREELIST not defined
static const bool kSupportsDoublyLinkedList = false;
inline void* FL_Next(void* t) {
return SLL_Next(t);
}
inline void FL_Init(void* t) {
SLL_SetNext(t, NULL);
}
inline void FL_Push(void** list, void* element) {
if (*list != element) {
SLL_Push(list, element);
return;
}
Log(kCrash, __FILE__, __LINE__, "Double Free of %p detected", element);
}
inline void* FL_Pop(void** list) {
return SLL_Pop(list);
}
// Removes |N| elements from a linked list to which |head| points.
// |head| will be modified to point to the new |head|. |start| and
// |end| will point to the first and last nodes of the range. Note
// that |end| will point to NULL after this function is called.
inline void FL_PopRange(void** head, int n, void** start, void** end) {
SLL_PopRange(head, n, start, end);
}
inline void FL_PushRange(void** head, void* start, void* end) {
SLL_PushRange(head, start, end);
}
inline size_t FL_Size(void* head) {
return SLL_Size(head);
}
#endif // TCMALLOC_USE_DOUBLYLINKED_FREELIST
} // namespace tcmalloc
#endif // TCMALLOC_FREE_LIST_H_