/thirdparty/breakpad/common/memory.h
http://github.com/tomahawk-player/tomahawk · C Header · 218 lines · 147 code · 33 blank · 38 comment · 17 complexity · 7a3e05f177804ae20aa256bb1f5d0242 MD5 · raw file
- // Copyright (c) 2009, 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.
- #ifndef GOOGLE_BREAKPAD_COMMON_MEMORY_H_
- #define GOOGLE_BREAKPAD_COMMON_MEMORY_H_
- #include <stdint.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <sys/mman.h>
- #ifdef __APPLE__
- #define sys_mmap mmap
- #define sys_mmap2 mmap
- #define sys_munmap munmap
- #define MAP_ANONYMOUS MAP_ANON
- #else
- #include "third_party/lss/linux_syscall_support.h"
- #endif
- namespace google_breakpad {
- // This is very simple allocator which fetches pages from the kernel directly.
- // Thus, it can be used even when the heap may be corrupted.
- //
- // There is no free operation. The pages are only freed when the object is
- // destroyed.
- class PageAllocator {
- public:
- PageAllocator()
- : page_size_(getpagesize()),
- last_(NULL),
- current_page_(NULL),
- page_offset_(0) {
- }
- ~PageAllocator() {
- FreeAll();
- }
- void *Alloc(unsigned bytes) {
- if (!bytes)
- return NULL;
- if (current_page_ && page_size_ - page_offset_ >= bytes) {
- uint8_t *const ret = current_page_ + page_offset_;
- page_offset_ += bytes;
- if (page_offset_ == page_size_) {
- page_offset_ = 0;
- current_page_ = NULL;
- }
- return ret;
- }
- const unsigned pages =
- (bytes + sizeof(PageHeader) + page_size_ - 1) / page_size_;
- uint8_t *const ret = GetNPages(pages);
- if (!ret)
- return NULL;
- page_offset_ = (page_size_ - (page_size_ * pages - (bytes + sizeof(PageHeader)))) % page_size_;
- current_page_ = page_offset_ ? ret + page_size_ * (pages - 1) : NULL;
- return ret + sizeof(PageHeader);
- }
- private:
- uint8_t *GetNPages(unsigned num_pages) {
- #ifdef __x86_64
- void *a = sys_mmap(NULL, page_size_ * num_pages, PROT_READ | PROT_WRITE,
- MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- #else
- void *a = sys_mmap2(NULL, page_size_ * num_pages, PROT_READ | PROT_WRITE,
- MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- #endif
- if (a == MAP_FAILED)
- return NULL;
- struct PageHeader *header = reinterpret_cast<PageHeader*>(a);
- header->next = last_;
- header->num_pages = num_pages;
- last_ = header;
- return reinterpret_cast<uint8_t*>(a);
- }
- void FreeAll() {
- PageHeader *next;
- for (PageHeader *cur = last_; cur; cur = next) {
- next = cur->next;
- sys_munmap(cur, cur->num_pages * page_size_);
- }
- }
- struct PageHeader {
- PageHeader *next; // pointer to the start of the next set of pages.
- unsigned num_pages; // the number of pages in this set.
- };
- const unsigned page_size_;
- PageHeader *last_;
- uint8_t *current_page_;
- unsigned page_offset_;
- };
- // A wasteful vector is like a normal std::vector, except that it's very much
- // simplier and it allocates memory from a PageAllocator. It's wasteful
- // because, when resizing, it always allocates a whole new array since the
- // PageAllocator doesn't support realloc.
- template<class T>
- class wasteful_vector {
- public:
- wasteful_vector(PageAllocator *allocator, unsigned size_hint = 16)
- : allocator_(allocator),
- a_((T*) allocator->Alloc(sizeof(T) * size_hint)),
- allocated_(size_hint),
- used_(0) {
- }
- T& back() {
- return a_[used_ - 1];
- }
- const T& back() const {
- return a_[used_ - 1];
- }
- bool empty() const {
- return used_ == 0;
- }
- void push_back(const T& new_element) {
- if (used_ == allocated_)
- Realloc(allocated_ * 2);
- a_[used_++] = new_element;
- }
- size_t size() const {
- return used_;
- }
- void resize(unsigned sz, T c = T()) {
- // No need to test "sz >= 0", as "sz" is unsigned.
- if (sz <= used_) {
- used_ = sz;
- } else {
- unsigned a = allocated_;
- if (sz > a) {
- while (sz > a) {
- a *= 2;
- }
- Realloc(a);
- }
- while (sz > used_) {
- a_[used_++] = c;
- }
- }
- }
- T& operator[](size_t index) {
- return a_[index];
- }
- const T& operator[](size_t index) const {
- return a_[index];
- }
- private:
- void Realloc(unsigned new_size) {
- T *new_array =
- reinterpret_cast<T*>(allocator_->Alloc(sizeof(T) * new_size));
- memcpy(new_array, a_, used_ * sizeof(T));
- a_ = new_array;
- allocated_ = new_size;
- }
- PageAllocator *const allocator_;
- T *a_; // pointer to an array of |allocated_| elements.
- unsigned allocated_; // size of |a_|, in elements.
- unsigned used_; // number of used slots in |a_|.
- };
- } // namespace google_breakpad
- inline void* operator new(size_t nbytes,
- google_breakpad::PageAllocator& allocator) {
- return allocator.Alloc(nbytes);
- }
- #endif // GOOGLE_BREAKPAD_COMMON_MEMORY_H_