| // 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_SNAPSHOT_MAC_MACH_O_IMAGE_SYMBOL_TABLE_READER_H_ |
| #define CRASHPAD_SNAPSHOT_MAC_MACH_O_IMAGE_SYMBOL_TABLE_READER_H_ |
| |
| #include <map> |
| #include <string> |
| |
| #include <mach/mach.h> |
| #include <stdint.h> |
| |
| #include "base/macros.h" |
| #include "snapshot/mac/mach_o_image_segment_reader.h" |
| #include "snapshot/mac/process_reader_mac.h" |
| #include "snapshot/mac/process_types.h" |
| #include "util/misc/initialization_state_dcheck.h" |
| |
| namespace crashpad { |
| |
| //! \brief A reader for symbol tables in Mach-O images mapped into another |
| //! process. |
| class MachOImageSymbolTableReader { |
| public: |
| //! \brief Information about a symbol in a module’s symbol table. |
| //! |
| //! This is a more minimal form of the `nlist` (or `nlist_64`) structure, |
| //! only containing the equivalent of the `n_value` and `n_sect` fields. |
| struct SymbolInformation { |
| //! \brief The address of the symbol as it exists in the symbol table, not |
| //! adjusted for any “slide.” |
| mach_vm_address_t value; |
| |
| //! \brief The 1-based section index in the module in which the symbol is |
| //! found. |
| //! |
| //! For symbols defined in a section (`N_SECT`), this is the section index |
| //! that can be passed to MachOImageReader::GetSectionAtIndex(), and \a |
| //! value will need to be adjusted for segment slide if the containing |
| //! segment slid when loaded. For absolute symbols (`N_ABS`), this will be |
| //! `NO_SECT` (`0`), and \a value must not be adjusted for segment slide. |
| uint8_t section; |
| }; |
| |
| // TODO(mark): Use std::unordered_map or a similar hash-based map? For now, |
| // std::map is fine because this map only stores external defined symbols, and |
| // there aren’t expected to be very many of those that performance would |
| // become a problem. In reality, std::unordered_map does not appear to provide |
| // a performance advantage. It appears that the memory copies currently done |
| // by ProcessMemoryMac::Read() have substantially more impact on symbol table |
| // operations. |
| // |
| // This is public so that the type is available to |
| // MachOImageSymbolTableReaderInitializer. |
| using SymbolInformationMap = std::map<std::string, SymbolInformation>; |
| |
| MachOImageSymbolTableReader(); |
| ~MachOImageSymbolTableReader(); |
| |
| //! \brief Reads the symbol table 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] symtab_command The `LC_SYMTAB` load command that identifies |
| //! the symbol table. |
| //! \param[in] dysymtab_command The `LC_DYSYMTAB` load command that identifies |
| //! dynamic symbol information within the symbol table. This load command |
| //! is not present in all modules, and this parameter may be `nullptr` for |
| //! modules that do not have this information. When present, \a |
| //! dysymtab_command is an optimization that allows the symbol table |
| //! reader to only examine symbol table entries known to be relevant for |
| //! its purposes. |
| //! \param[in] linkedit_segment The `__LINKEDIT` segment. This segment should |
| //! contain the data referenced by \a symtab_command and \a |
| //! dysymtab_command. This may be any segment in the module, but by |
| //! convention, the name `__LINKEDIT` is used for this purpose. |
| //! \param[in] module_info A string to be used in logged messages. This string |
| //! is for diagnostic purposes only, and may be empty. |
| //! |
| //! \return `true` if the symbol table was read successfully. `false` |
| //! otherwise, with an appropriate message logged. |
| bool Initialize(ProcessReaderMac* process_reader, |
| const process_types::symtab_command* symtab_command, |
| const process_types::dysymtab_command* dysymtab_command, |
| const MachOImageSegmentReader* linkedit_segment, |
| const std::string& module_info); |
| |
| //! \brief Looks up a symbol in the image’s symbol table. |
| //! |
| //! The returned information captures the symbol as it exists in the image’s |
| //! symbol table, not adjusted for any “slide.” |
| //! |
| //! \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. |
| //! |
| //! \return A SymbolInformation* object with information about the symbol if |
| //! it was found, or `nullptr` if the symbol was not found or if an error |
| //! occurred. On error, a warning message will also be logged. The caller |
| //! does not take ownership; the lifetime of the returned object is scoped |
| //! to the lifetime of this MachOImageSymbolTableReader object. |
| //! |
| //! \note Symbol values returned via this interface are not adjusted for |
| //! “slide.” For slide-adjusted values, use the higher-level |
| //! MachOImageReader::LookUpExternalDefinedSymbol() interface. |
| const SymbolInformation* LookUpExternalDefinedSymbol( |
| const std::string& name) const; |
| |
| private: |
| SymbolInformationMap external_defined_symbols_; |
| InitializationStateDcheck initialized_; |
| |
| DISALLOW_COPY_AND_ASSIGN(MachOImageSymbolTableReader); |
| }; |
| |
| } // namespace crashpad |
| |
| #endif // CRASHPAD_SNAPSHOT_MAC_MACH_O_IMAGE_SYMBOL_TABLE_READER_H_ |