// 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_LINUX_MEMORY_MAP_H_
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#define CRASHPAD_UTIL_LINUX_MEMORY_MAP_H_
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#include <sys/types.h>
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#include <memory>
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#include <string>
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#include <vector>
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#include "util/linux/address_types.h"
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#include "util/linux/checked_linux_address_range.h"
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#include "util/linux/ptrace_connection.h"
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#include "util/misc/initialization_state_dcheck.h"
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namespace crashpad {
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//! \brief Accesses information about mapped memory in another process.
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//!
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//! The target process must be stopped to guarantee correct mappings. If the
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//! target process is not stopped, mappings may be invalid after the return from
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//! Initialize(), and even mappings existing at the time Initialize() was called
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//! may not be found.
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class MemoryMap {
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public:
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//! \brief Information about a mapped region of memory.
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struct Mapping {
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Mapping();
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bool Equals(const Mapping& other) const;
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std::string name;
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CheckedLinuxAddressRange range;
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off64_t offset;
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dev_t device;
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ino_t inode;
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bool readable;
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bool writable;
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bool executable;
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bool shareable;
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};
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MemoryMap();
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~MemoryMap();
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//! \brief Initializes this object with information about the mapped memory
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//! regions in the process connected via \a connection.
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//!
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//! This method must be called successfully prior to calling any other method
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//! in this class. This method may only be called once.
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//!
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//! \param[in] connection A connection to the process create a map for.
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//!
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//! \return `true` on success, `false` on failure with a message logged.
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bool Initialize(PtraceConnection* connection);
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//! \return The Mapping containing \a address or `nullptr` if no match is
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//! found. The caller does not take ownership of this object. It is scoped
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//! to the lifetime of the MemoryMap object that it was obtained from.
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const Mapping* FindMapping(LinuxVMAddress address) const;
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//! \return The Mapping with the lowest base address whose name is \a name or
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//! `nullptr` if no match is found. The caller does not take ownership of
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//! this object. It is scoped to the lifetime of the MemoryMap object that
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//! it was obtained from.
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const Mapping* FindMappingWithName(const std::string& name) const;
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//! \brief An abstract base class for iterating over ordered sets of mappings
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//! in a MemoryMap.
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class Iterator {
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public:
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virtual ~Iterator() = default;
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//! \return the mapping pointed to by the iterator and advance the iterator
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//! to the next mapping. If there are no more mappings, this method
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//! returns `nullptr` on all subsequent invocations.
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virtual const Mapping* Next() = 0;
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//! \return the number of mappings remaining.
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virtual unsigned int Count() = 0;
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protected:
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Iterator() = default;
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};
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//! \brief Find possible initial mappings of files mapped over several
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//! segments.
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//!
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//! Executables and libaries are typically loaded into several mappings with
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//! varying permissions for different segments. Portions of an ELF file may
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//! be mapped multiple times as part of loading the file, for example, when
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//! initializing GNU_RELRO segments.
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//!
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//! This method searches for mappings at or below \a mapping in memory that
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//! are mapped from the same file as \a mapping from offset 0.
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//!
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//! On Android, ELF modules may be loaded from within a zipfile, so this
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//! method may return mappings whose offset is not 0.
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//!
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//! This method is intended to help identify the possible base address for
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//! loaded modules, but it is the caller's responsibility to determine which
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//! returned mapping is correct.
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//!
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//! If \a mapping does not refer to a valid mapping, an empty vector will be
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//! returned and a message will be logged. If \a mapping is found but does not
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//! map a file, \a mapping is returned in \a possible_starts.
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//!
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//! \param[in] mapping A Mapping whose series to find the start of.
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//! \return a reverse iterator over the possible mapping starts, starting from
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//! the mapping with highest base address.
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std::unique_ptr<Iterator> FindFilePossibleMmapStarts(
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const Mapping& mapping) const;
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//! \return A reverse iterator over all mappings in the MemoryMap from \a
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//! mapping to the start of the MemoryMap.
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std::unique_ptr<Iterator> ReverseIteratorFrom(const Mapping& mapping) const;
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private:
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std::vector<Mapping> mappings_;
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InitializationStateDcheck initialized_;
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};
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} // namespace crashpad
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#endif // CRASHPAD_UTIL_LINUX_MEMORY_MAP_H_
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