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+// 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>
+
+#include <memory>
+#include <vector>
+
+#if defined(MEMORY_SANITIZER)
+#include <sanitizer/msan_interface.h>
+#endif
+
+#ifdef __APPLE__
+#define sys_mmap 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),
+ pages_allocated_(0) {
+ }
+
+ ~PageAllocator() {
+ FreeAll();
+ }
+
+ void *Alloc(size_t 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 size_t 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);
+ }
+
+ // Checks whether the page allocator owns the passed-in pointer.
+ // This method exists for testing pursposes only.
+ bool OwnsPointer(const void* p) {
+ for (PageHeader* header = last_; header; header = header->next) {
+ const char* current = reinterpret_cast<char*>(header);
+ if ((p >= current) && (p < current + header->num_pages * page_size_))
+ return true;
+ }
+
+ return false;
+ }
+
+ unsigned long pages_allocated() { return pages_allocated_; }
+
+ private:
+ uint8_t *GetNPages(size_t num_pages) {
+ void *a = sys_mmap(NULL, page_size_ * num_pages, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (a == MAP_FAILED)
+ return NULL;
+
+#if defined(MEMORY_SANITIZER)
+ // We need to indicate to MSan that memory allocated through sys_mmap is
+ // initialized, since linux_syscall_support.h doesn't have MSan hooks.
+ __msan_unpoison(a, page_size_ * num_pages);
+#endif
+
+ struct PageHeader *header = reinterpret_cast<PageHeader*>(a);
+ header->next = last_;
+ header->num_pages = num_pages;
+ last_ = header;
+
+ pages_allocated_ += num_pages;
+
+ 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.
+ size_t num_pages; // the number of pages in this set.
+ };
+
+ const size_t page_size_;
+ PageHeader *last_;
+ uint8_t *current_page_;
+ size_t page_offset_;
+ unsigned long pages_allocated_;
+};
+
+// Wrapper to use with STL containers
+template <typename T>
+struct PageStdAllocator : public std::allocator<T> {
+ typedef typename std::allocator<T>::pointer pointer;
+ typedef typename std::allocator<T>::size_type size_type;
+
+ explicit PageStdAllocator(PageAllocator& allocator) : allocator_(allocator),
+ stackdata_(NULL),
+ stackdata_size_(0)
+ {}
+
+ template <class Other> PageStdAllocator(const PageStdAllocator<Other>& other)
+ : allocator_(other.allocator_),
+ stackdata_(nullptr),
+ stackdata_size_(0)
+ {}
+
+ explicit PageStdAllocator(PageAllocator& allocator,
+ pointer stackdata,
+ size_type stackdata_size) : allocator_(allocator),
+ stackdata_(stackdata),
+ stackdata_size_(stackdata_size)
+ {}
+
+ inline pointer allocate(size_type n, const void* = 0) {
+ const size_type size = sizeof(T) * n;
+ if (size <= stackdata_size_) {
+ return stackdata_;
+ }
+ return static_cast<pointer>(allocator_.Alloc(size));
+ }
+
+ inline void deallocate(pointer, size_type) {
+ // The PageAllocator doesn't free.
+ }
+
+ template <typename U> struct rebind {
+ typedef PageStdAllocator<U> other;
+ };
+
+ private:
+ // Silly workaround for the gcc from Android's ndk (gcc 4.6), which will
+ // otherwise complain that `other.allocator_` is private in the constructor
+ // code.
+ template<typename Other> friend struct PageStdAllocator;
+
+ PageAllocator& allocator_;
+ pointer stackdata_;
+ size_type stackdata_size_;
+};
+
+// A wasteful vector is a std::vector, except that 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 std::vector<T, PageStdAllocator<T> > {
+ public:
+ wasteful_vector(PageAllocator* allocator, unsigned size_hint = 16)
+ : std::vector<T, PageStdAllocator<T> >(PageStdAllocator<T>(*allocator)) {
+ std::vector<T, PageStdAllocator<T> >::reserve(size_hint);
+ }
+ protected:
+ wasteful_vector(PageStdAllocator<T> allocator)
+ : std::vector<T, PageStdAllocator<T> >(allocator) {}
+};
+
+// auto_wasteful_vector allocates space on the stack for N entries to avoid
+// using the PageAllocator for small data, while still allowing for larger data.
+template<class T, unsigned int N>
+class auto_wasteful_vector : public wasteful_vector<T> {
+ T stackdata_[N];
+ public:
+ auto_wasteful_vector(PageAllocator* allocator)
+ : wasteful_vector<T>(
+ PageStdAllocator<T>(*allocator,
+ &stackdata_[0],
+ sizeof(stackdata_))) {
+ std::vector<T, PageStdAllocator<T> >::reserve(N);
+ }
+};
+
+} // namespace google_breakpad
+
+inline void* operator new(size_t nbytes,
+ google_breakpad::PageAllocator& allocator) {
+ return allocator.Alloc(nbytes);
+}
+
+#endif // GOOGLE_BREAKPAD_COMMON_MEMORY_H_