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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 CLIENT_LINUX_HANDLER_MEMORY_H_
#define CLIENT_LINUX_HANDLER_MEMORY_H_
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include "common/linux/linux_syscall_support.h"
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) {
}
void push_back(const T& new_element) {
if (used_ == allocated_)
Realloc(allocated_ * 2);
a_[used_++] = new_element;
}
size_t size() const {
return used_;
}
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 // CLIENT_LINUX_HANDLER_MEMORY_H_
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