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708367f5ba
9d26012e9c73 relaxed the requirement on ScopedMmap such that the length of the region supervised no longer needed to be provided as a round number of pages. This was accomplished by internally rounding up the provided length to a page length. Unfortunately, this made ScopedMmap::len() return something other than the passed-in length, which is undesirable. This change makes ScopedMmap store the passed-in length internally, making it available unmodified via the accessor, and rounding it up to page length at internal points of use. Change-Id: I827925af68e38f33bfa3cee535db0f098884fc6b Reviewed-on: https://chromium-review.googlesource.com/c/1492774 Commit-Queue: Mark Mentovai <mark@chromium.org> Reviewed-by: Joshua Peraza <jperaza@chromium.org>
111 lines
3.9 KiB
C++
111 lines
3.9 KiB
C++
// Copyright 2017 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef CRASHPAD_UTIL_POSIX_SCOPED_MMAP_H_
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#define CRASHPAD_UTIL_POSIX_SCOPED_MMAP_H_
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#include "base/macros.h"
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#include <sys/mman.h>
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#include <sys/types.h>
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#include "util/misc/from_pointer_cast.h"
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namespace crashpad {
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//! \brief Maintains a memory-mapped region created by `mmap()`.
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//!
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//! On destruction, any memory-mapped region managed by an object of this class
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//! will be released by calling `munmap()`.
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class ScopedMmap {
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public:
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ScopedMmap();
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~ScopedMmap();
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//! \brief Releases the memory-mapped region by calling `munmap()`.
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//!
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//! \return `true` on success. `false` on failure, with a message logged.
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bool Reset();
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//! \brief Releases any existing memory-mapped region and sets the object to
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//! maintain an already-established mapping.
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//!
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//! If \a addr and \a len indicate a region that overlaps with the existing
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//! memory-mapped region, only the portion of the existing memory-mapped
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//! region that does not overlap the new region, if any, will be released.
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//!
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//! \param[in] addr The base address of the existing memory-mapped region to
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//! maintain.
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//! \param[in] len The size of the existing memory-mapped region to maintain.
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//!
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//! \return `true` on success. `false` on failure, with a message logged.
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bool ResetAddrLen(void* addr, size_t len);
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//! \brief Releases any existing memory-mapped region and establishes a new
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//! one by calling `mmap()`.
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//!
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//! The parameters to this method are passed directly to `mmap()`.
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//!
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//! \return `true` on success. `false` on failure, with a message logged. A
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//! message will also be logged on failure to release any existing
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//! memory-mapped region, but this will not preclude `mmap()` from being
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//! called or a new mapping from being established, and if such a call to
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//! `mmap()` is successful, this method will return `true`.
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bool ResetMmap(void* addr,
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size_t len,
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int prot,
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int flags,
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int fd,
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off_t offset);
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//! \brief Sets the protection of the memory-mapped region by calling
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//! `mprotect()`.
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//!
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//! \a prot is passed directly to `mprotect()`.
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//!
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//! \return `true` on success. `false` on failure, with a message logged.
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bool Mprotect(int prot);
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//! \return Whether this object is managing a valid memory-mapped region.
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bool is_valid() const { return addr_ != MAP_FAILED; }
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//! \brief Returns the base address of the memory-mapped region.
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void* addr() const { return addr_; }
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//! \brief Returns the base address of the memory-mapped region, casted to
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//! a type of the caller’s choosing.
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template <typename T>
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T addr_as() const {
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return FromPointerCast<T>(addr_);
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}
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//! \brief Returns the size of the memory-mapped region.
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//!
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//! This is the value originally passed to ResetAddrLen() or ResetMmap(), or
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//! after Reset(), `0`. It may not be a round number of pages. Providing the
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//! passed-in value is intended to ease tracking the intended lengths of
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//! memory-mapped regions backed by files whose sizes are not whole pages.
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size_t len() const { return len_; }
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private:
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void* addr_ = MAP_FAILED;
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size_t len_ = 0;
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DISALLOW_COPY_AND_ASSIGN(ScopedMmap);
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};
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} // namespace crashpad
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#endif // CRASHPAD_UTIL_POSIX_SCOPED_MMAP_H_
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