Create snapshot/mac and move some files from snapshot and util to there

util/mac/mach_o_image_reader.h

-// Copyright 2014 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_MAC_MACH_O_IMAGE_READER_H_
-#define CRASHPAD_UTIL_MAC_MACH_O_IMAGE_READER_H_
-
-#include <mach/mach.h>
-#include <stdint.h>
-
-#include <map>
-#include <string>
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "util/misc/initialization_state_dcheck.h"
-#include "util/misc/uuid.h"
-#include "util/stdlib/pointer_container.h"
-#include "util/mac/process_types.h"
-
-namespace crashpad {
-
-class MachOImageSegmentReader;
-class MachOImageSymbolTableReader;
-class ProcessReader;
-
-//! \brief A reader for Mach-O images mapped into another process.
-//!
-//! This class is capable of reading both 32-bit (`mach_header`/`MH_MAGIC`) and
-//! 64-bit (`mach_header_64`/`MH_MAGIC_64`) images based on the bitness of the
-//! remote process.
-class MachOImageReader {
- public:
-  MachOImageReader();
-  ~MachOImageReader();
-
-  //! \brief Reads the Mach-O image file’s load commands from another process.
-  //!
-  //! This method must only be called once on an object. This method must be
-  //! called successfully before any other method in this class may be called.
-  //!
-  //! \param[in] process_reader The reader for the remote process.
-  //! \param[in] address The address, in the remote process’ address space,
-  //!     where the `mach_header` or `mach_header_64` at the beginning of the
-  //!     image to be read is located. This address can be determined by reading
-  //!     the remote process’ dyld information (see
-  //!     util/mac/process_types/dyld_images.proctype).
-  //! \param[in] name The module’s name, a string to be used in logged messages.
-  //!     This string is for diagnostic purposes only, and may be empty.
-  //!
-  //! \return `true` if the image was read successfully, including all load
-  //!     commands. `false` otherwise, with an appropriate message logged.
-  bool Initialize(ProcessReader* process_reader,
-                  mach_vm_address_t address,
-                  const std::string& name);
-
-  //! \brief Returns the Mach-O file type.
-  //!
-  //! This value comes from the `filetype` field of the `mach_header` or
-  //! `mach_header_64`. Common values include `MH_EXECUTE`, `MH_DYLIB`,
-  //! `MH_DYLINKER`, and `MH_BUNDLE`.
-  uint32_t FileType() const { return file_type_; }
-
-  //! \brief Returns the Mach-O image’s load address.
-  //!
-  //! This is the value passed as \a address to Initialize().
-  mach_vm_address_t Address() const { return address_; }
-
-  //! \brief Returns the mapped size of the Mach-O image’s `__TEXT` segment.
-  //!
-  //! Note that this is returns only the size of the `__TEXT` segment, not of
-  //! any other segment. This is because the interface only allows one load
-  //! address and size to be reported, but Mach-O image files may consist of
-  //! multiple discontiguous segments. By convention, the `__TEXT` segment is
-  //! always mapped at the beginning of a Mach-O image file, and it is the most
-  //! useful for the expected intended purpose of collecting data to obtain
-  //! stack backtraces. The implementation insists during initialization that
-  //! the `__TEXT` segment be mapped at the beginning of the file.
-  //!
-  //! In practice, discontiguous segments are only found for images that have
-  //! loaded out of the dyld shared cache, but the `__TEXT` segment’s size is
-  //! returned for modules that loaded with contiguous segments as well for
-  //! consistency.
-  mach_vm_size_t Size() const { return size_; }
-
-  //! \brief Returns the Mach-O image’s “slide,” the difference between its
-  //!     actual load address and its preferred load address.
-  //!
-  //! “Slide” is computed by subtracting the `__TEXT` segment’s preferred load
-  //! address from its actual load address. It will be reported as a positive
-  //! offset when the actual load address is greater than the preferred load
-  //! address. The preferred load address is taken to be the segment’s reported
-  //! `vmaddr` value.
-  mach_vm_size_t Slide() const { return slide_; }
-
-  //! \brief Obtain segment information by segment name.
-  //!
-  //! \param[in] segment_name The name of the segment to search for, for
-  //!     example, `"__TEXT"`.
-  //!
-  //! \return A pointer to the segment information if it was found, or `nullptr`
-  //!     if it was not found. The caller does not take ownership; the lifetime
-  //!     of the returned object is scoped to the lifetime of this
-  //!     MachOImageReader object.
-  const MachOImageSegmentReader* GetSegmentByName(
-      const std::string& segment_name) const;
-
-  //! \brief Obtain section information by segment and section name.
-  //!
-  //! \param[in] segment_name The name of the segment to search for, for
-  //!     example, `"__TEXT"`.
-  //! \param[in] section_name The name of the section within the segment to
-  //!     search for, for example, `"__text"`.
-  //! \param[out] address The actual address that the section was loaded at in
-  //!     memory, taking any “slide” into account if the section did not load at
-  //!     its preferred address as stored in the Mach-O image file. This
-  //!     parameter can be `nullptr`.
-  //!
-  //! \return A pointer to the section information if it was found, or `nullptr`
-  //!     if it was not found. The caller does not take ownership; the lifetime
-  //!     of the returned object is scoped to the lifetime of this
-  //!     MachOImageReader object.
-  //!
-  //! No parameter is provided for the section’s size, because it can be
-  //! obtained from the returned process_types::section::size field.
-  //!
-  //! \note The process_types::section::addr field gives the section’s preferred
-  //!     load address as stored in the Mach-O image file, and is not adjusted
-  //!     for any “slide” that may have occurred when the image was loaded. Use
-  //!     \a address to obtain the section’s actual load address.
-  const process_types::section* GetSectionByName(
-      const std::string& segment_name,
-      const std::string& section_name,
-      mach_vm_address_t* address) const;
-
-  //! \brief Obtain section information by section index.
-  //!
-  //! \param[in] index The index of the section to return, in the order that it
-  //!     appears in the segment load commands. This is a 1-based index,
-  //!     matching the section number values used for `nlist::n_sect`.
-  //! \param[out] containing_segment The segment that contains the section.
-  //!     This parameter can be `nullptr`. The caller does not take ownership;
-  //!     the lifetime of the returned object is scoped to the lifetime of this
-  //!     MachOImageReader object.
-  //! \param[out] address The actual address that the section was loaded at in
-  //!     memory, taking any “slide” into account if the section did not load at
-  //!     its preferred address as stored in the Mach-O image file. This
-  //!     parameter can be `nullptr`.
-  //!
-  //! \return A pointer to the section information. If \a index is out of range,
-  //!     logs a warning and returns `nullptr`. The caller does not take
-  //!     ownership; the lifetime of the returned object is scoped to the
-  //!     lifetime of this MachOImageReader object.
-  //!
-  //! No parameter is provided for the section’s size, because it can be
-  //! obtained from the returned process_types::section::size field.
-  //!
-  //! \note The process_types::section::addr field gives the section’s preferred
-  //!     load address as stored in the Mach-O image file, and is not adjusted
-  //!     for any “slide” that may have occurred when the image was loaded. Use
-  //!     \a address to obtain the section’s actual load address.
-  //! \note Unlike MachOImageSegmentReader::GetSectionAtIndex(), this method
-  //!     accepts out-of-range values for \a index, and returns `nullptr`
-  //!     instead of aborting execution upon encountering an out-of-range value.
-  //!     This is because a Mach-O image file’s symbol table refers to this
-  //!     per-module section index, and an out-of-range index in that case
-  //!     should be treated as a data error (where the data is beyond this
-  //!     code’s control) and handled non-fatally by reporting the error to the
-  //!     caller.
-  const process_types::section* GetSectionAtIndex(
-      size_t index,
-      const MachOImageSegmentReader** containing_segment,
-      mach_vm_address_t* address) const;
-
-  //! \brief Looks up a symbol in the image’s symbol table.
-  //!
-  //! This method is capable of locating external defined symbols. Specifically,
-  //! this method can look up symbols that have these charcteristics:
-  //!  - `N_STAB` (debugging) and `N_PEXT` (private external) must not be set.
-  //!  - `N_EXT` (external) must be set.
-  //!  - The type must be `N_ABS` (absolute) or `N_SECT` (defined in section).
-  //!
-  //! `N_INDR` (indirect), `N_UNDF` (undefined), and `N_PBUD` (prebound
-  //! undefined) symbols cannot be located through this mechanism.
-  //!
-  //! \param[in] name The name of the symbol to look up, “mangled” or
-  //!     “decorated” appropriately. For example, use `"_main"` to look up the
-  //!     symbol for the C `main()` function, and use `"__Z4Funcv"` to look up
-  //!     the symbol for the C++ `Func()` function. Contrary to `dlsym()`, the
-  //!     leading underscore must not be stripped when using this interface.
-  //! \param[out] value If the lookup was successful, this will be set to the
-  //!     value of the symbol, adjusted for any “slide” as needed. The value can
-  //!     be used as an address in the remote process’ address space where the
-  //!     pointee of the symbol exists in memory.
-  //!
-  //! \return `true` if the symbol lookup was successful and the symbol was
-  //!     found. `false` otherwise, including error conditions (for which a
-  //!     warning message will be logged), modules without symbol tables, and
-  //!     symbol names not found in the symbol table.
-  //!
-  //! \note Symbol values returned via this interface are adjusted for “slide”
-  //!     as appropriate, in contrast to the underlying implementation,
-  //!     MachOImageSymbolTableReader::LookUpExternalDefinedSymbol().
-  //!
-  //! \warning Symbols that are resolved by running symbol resolvers
-  //!     (`.symbol_resolver`) are not properly handled by this interface. The
-  //!     address of the symbol resolver is returned because that’s what shows
-  //!     up in the symbol table, rather than the effective address of the
-  //!     resolved symbol as used by dyld after running the resolver. The only
-  //!     way to detect this situation would be to read the `LC_DYLD_INFO` or
-  //!     `LC_DYLD_INFO_ONLY` load command if present and looking for the
-  //!     `EXPORT_SYMBOL_FLAGS_STUB_AND_RESOLVER` flag, but that would just be
-  //!     able to detect symbols with a resolver, it would not be able to
-  //!     resolve them from out-of-process, so it’s not currently done.
-  bool LookUpExternalDefinedSymbol(const std::string& name,
-                                   mach_vm_address_t* value) const;
-
-  //! \brief Returns a Mach-O dylib image’s current version.
-  //!
-  //! This information comes from the `dylib_current_version` field of a dylib’s
-  //! `LC_ID_DYLIB` load command. For dylibs without this load command, `0` will
-  //! be returned.
-  //!
-  //! This method may only be called on Mach-O images for which FileType()
-  //! returns `MH_DYLIB`.
-  uint32_t DylibVersion() const;
-
-  //! \brief Returns a Mach-O image’s source version.
-  //!
-  //! This information comes from a Mach-O image’s `LC_SOURCE_VERSION` load
-  //! command. For Mach-O images without this load command, `0` will be
-  //! returned.
-  uint64_t SourceVersion() const { return source_version_; }
-
-  //! \brief Returns a Mach-O image’s UUID.
-  //!
-  //! This information comes from a Mach-O image’s `LC_UUID` load command. For
-  //! Mach-O images without this load command, a zeroed-out UUID value will be
-  //! returned.
-  //
-  // UUID is a name in this scope (referring to this method), so the parameter’s
-  // type needs to be qualified with |crashpad::|.
-  void UUID(crashpad::UUID* uuid) const;
-
-  //! \brief Returns the dynamic linker’s pathname.
-  //!
-  //! The dynamic linker is normally /usr/lib/dyld.
-  //!
-  //! For executable images (those with file type `MH_EXECUTE`), this is the
-  //! name provided in the `LC_LOAD_DYLINKER` load command, if any. For dynamic
-  //! linker images (those with file type `MH_DYLINKER`), this is the name
-  //! provided in the `LC_ID_DYLINKER` load command. In other cases, this will
-  //! be empty.
-  std::string DylinkerName() const { return dylinker_name_; }
-
- private:
-  // A generic helper routine for the other Read*Command() methods.
-  template <typename T>
-  bool ReadLoadCommand(mach_vm_address_t load_command_address,
-                       const std::string& load_command_info,
-                       uint32_t expected_load_command_id,
-                       T* load_command);
-
-  // The Read*Command() methods are subroutines called by Initialize(). They are
-  // responsible for reading a single load command. They may update the member
-  // fields of their MachOImageReader object. If they can’t make sense of a load
-  // command, they return false.
-  bool ReadSegmentCommand(mach_vm_address_t load_command_address,
-                          const std::string& load_command_info);
-  bool ReadSymTabCommand(mach_vm_address_t load_command_address,
-                         const std::string& load_command_info);
-  bool ReadDySymTabCommand(mach_vm_address_t load_command_address,
-                           const std::string& load_command_info);
-  bool ReadIdDylibCommand(mach_vm_address_t load_command_address,
-                          const std::string& load_command_info);
-  bool ReadDylinkerCommand(mach_vm_address_t load_command_address,
-                           const std::string& load_command_info);
-  bool ReadUUIDCommand(mach_vm_address_t load_command_address,
-                       const std::string& load_command_info);
-  bool ReadSourceVersionCommand(mach_vm_address_t load_command_address,
-                                const std::string& load_command_info);
-  bool ReadUnexpectedCommand(mach_vm_address_t load_command_address,
-                             const std::string& load_command_info);
-
-  // Performs deferred initialization of the symbol table. Because a module’s
-  // symbol table is often not needed, this is not handled in Initialize(), but
-  // is done lazily, on-demand as needed.
-  //
-  // symbol_table_initialized_ will be transitioned to the appropriate state. If
-  // initialization completes successfully, this will be the valid state.
-  // Otherwise, it will be left in the invalid state and a warning message will
-  // be logged.
-  //
-  // Note that if the object contains no symbol table, symbol_table_initialized_
-  // will be set to the valid state, but symbol_table_ will be nullptr.
-  void InitializeSymbolTable() const;
-
-  PointerVector<MachOImageSegmentReader> segments_;
-  std::map<std::string, size_t> segment_map_;
-  std::string module_info_;
-  std::string dylinker_name_;
-  crashpad::UUID uuid_;
-  mach_vm_address_t address_;
-  mach_vm_size_t size_;
-  mach_vm_size_t slide_;
-  uint64_t source_version_;
-  scoped_ptr<process_types::symtab_command> symtab_command_;
-  scoped_ptr<process_types::dysymtab_command> dysymtab_command_;
-
-  // symbol_table_ (and symbol_table_initialized_) are mutable in order to
-  // maintain LookUpExternalDefinedSymbol() as a const interface while allowing
-  // lazy initialization via InitializeSymbolTable(). This is logical
-  // const-ness, not physical const-ness.
-  mutable scoped_ptr<MachOImageSymbolTableReader> symbol_table_;
-
-  scoped_ptr<process_types::dylib_command> id_dylib_command_;
-  ProcessReader* process_reader_;  // weak
-  uint32_t file_type_;
-  InitializationStateDcheck initialized_;
-
-  // symbol_table_initialized_ protects symbol_table_: symbol_table_ can only
-  // be used when symbol_table_initialized_ is valid, although
-  // symbol_table_initialized_ being valid doesn’t imply that symbol_table_ is
-  // set. symbol_table_initialized_ will be valid without symbol_table_ being
-  // set in modules that have no symbol table.
-  mutable InitializationState symbol_table_initialized_;
-
-  DISALLOW_COPY_AND_ASSIGN(MachOImageReader);
-};
-
-}  // namespace crashpad
-
-#endif  // CRASHPAD_UTIL_MAC_MACH_O_IMAGE_READER_H_