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// Copyright 2017 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef CRASHPAD_UTIL_POSIX_SCOPED_MMAP_H_
#define CRASHPAD_UTIL_POSIX_SCOPED_MMAP_H_
#include "base/macros.h"
#include <sys/mman.h>
#include <sys/types.h>
#include "util/misc/from_pointer_cast.h"
namespace crashpad {
//! \brief Maintains a memory-mapped region created by `mmap()`.
//!
//! On destruction, any memory-mapped region managed by an object of this class
//! will be released by calling `munmap()`.
class ScopedMmap {
public:
ScopedMmap();
~ScopedMmap();
//! \brief Releases the memory-mapped region by calling `munmap()`.
//!
//! \return `true` on success. `false` on failure, with a message logged.
bool Reset();
//! \brief Releases any existing memory-mapped region and sets the object to
//! maintain an already-established mapping.
//!
//! If \a addr and \a len indicate a region that overlaps with the existing
//! memory-mapped region, only the portion of the existing memory-mapped
//! region that does not overlap the new region, if any, will be released.
//!
//! \param[in] addr The base address of the existing memory-mapped region to
//! maintain.
//! \param[in] len The size of the existing memory-mapped region to maintain.
//!
//! \return `true` on success. `false` on failure, with a message logged.
bool ResetAddrLen(void* addr, size_t len);
//! \brief Releases any existing memory-mapped region and establishes a new
//! one by calling `mmap()`.
//!
//! The parameters to this method are passed directly to `mmap()`.
//!
//! \return `true` on success. `false` on failure, with a message logged. A
//! message will also be logged on failure to release any existing
//! memory-mapped region, but this will not preclude `mmap()` from being
//! called or a new mapping from being established, and if such a call to
//! `mmap()` is successful, this method will return `true`.
bool ResetMmap(void* addr,
size_t len,
int prot,
int flags,
int fd,
off_t offset);
//! \brief Sets the protection of the memory-mapped region by calling
//! `mprotect()`.
//!
//! \a prot is passed directly to `mprotect()`.
//!
//! \return `true` on success. `false` on failure, with a message logged.
bool Mprotect(int prot);
//! \return Whether this object is managing a valid memory-mapped region.
bool is_valid() const { return addr_ != MAP_FAILED; }
//! \brief Returns the base address of the memory-mapped region.
void* addr() const { return addr_; }
//! \brief Returns the base address of the memory-mapped region, casted to
//! a type of the caller’s choosing.
template <typename T>
T addr_as() const {
return FromPointerCast<T>(addr_);
}
//! \brief Returns the size of the memory-mapped region.
//!
//! This is the value originally passed to ResetAddrLen() or ResetMmap(), or
//! after Reset(), `0`. It may not be a round number of pages. Providing the
//! passed-in value is intended to ease tracking the intended lengths of
//! memory-mapped regions backed by files whose sizes are not whole pages.
size_t len() const { return len_; }
private:
void* addr_ = MAP_FAILED;
size_t len_ = 0;
DISALLOW_COPY_AND_ASSIGN(ScopedMmap);
};
} // namespace crashpad
#endif // CRASHPAD_UTIL_POSIX_SCOPED_MMAP_H_