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Diffstat (limited to 'elff/elf_file.h')
| -rw-r--r-- | elff/elf_file.h | 621 |
1 files changed, 621 insertions, 0 deletions
diff --git a/elff/elf_file.h b/elff/elf_file.h new file mode 100644 index 0000000..6c57bde --- /dev/null +++ b/elff/elf_file.h @@ -0,0 +1,621 @@ +/* Copyright (C) 2007-2010 The Android Open Source Project
+**
+** This software is licensed under the terms of the GNU General Public
+** License version 2, as published by the Free Software Foundation, and
+** may be copied, distributed, and modified under those terms.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+** GNU General Public License for more details.
+*/
+
+/*
+ * Contains declaration of ElfFile classes that encapsulate an ELF file.
+ */
+
+#ifndef ELFF_ELF_FILE_H_
+#define ELFF_ELF_FILE_H_
+
+#include "dwarf_die.h"
+#include "elf_mapped_section.h"
+#include "elff_api.h"
+
+/* Encapsulates architecture-independent functionality of an ELF file.
+ *
+ * This class is a base class for templated ElfFileImpl. This class implements
+ * functionality around an ELF file that is independent from particulars of the
+ * ELF's CPU architectire, while ElfFileImpl handles all particulars of CPU
+ * architecture (namely, 32 or 64-bit), for which ELF file has been built.
+ *
+ * NOTE: This class operates on ELF sections that have been mapped to memory.
+ *
+ */
+class ElfFile {
+ public:
+ /* Constructs ElfFile instance. */
+ ElfFile();
+
+ /* Destructs ElfFile instance. */
+ virtual ~ElfFile();
+
+ /* Creates ElfFileImpl instance, depending on ELF file CPU architecture.
+ * This method will collect initial information about requested ELF file,
+ * and will instantiate appropriate ElfFileImpl class object for it.
+ * Param:
+ * path - Full path to the ELF file.
+ * Return:
+ * Initialized ElfFileImpl instance, typecasted back to ElfFile object on
+ * success, or NULL on failure, with errno providing extended error
+ * information.
+ */
+ static ElfFile* Create(const char* path);
+
+ /* Checks if ELF file is a 64, or 32-bit ELF file. */
+ bool is_ELF_64() const {
+ return is_ELF_64_;
+ }
+ bool is_ELF_32() const {
+ return !is_ELF_64_;
+ }
+
+ /* Checks if ELF file data format is big, or little-endian. */
+ bool is_elf_big_endian() const {
+ return is_elf_big_endian_;
+ }
+ bool is_elf_little_endian() const {
+ return !is_elf_big_endian_;
+ }
+
+ /* Checks whether or not endianness of CPU this library is built for matches
+ * endianness of the ELF file that is represented with this instance. */
+ bool same_endianness() const {
+ return same_endianness_;
+ }
+
+ /* Checks if format of DWARF data in this file is 64, or 32-bit. */
+ bool is_DWARF_64() const {
+ return is_DWARF_64_;
+ }
+ bool is_DWARF_32() const {
+ return !is_DWARF_64_;
+ }
+
+ /* Gets DWARF objects allocator for this instance. */
+ class ElfAllocator* allocator() const {
+ return allocator_;
+ }
+
+ /* Gets head of compilation unit list, collected during parsing of this file.
+ * NOTE: list of collected compilation units returned from this method is
+ * in reverse order relatively to the order CUs have been added to the list
+ * during ELF file parsing.
+ */
+ class DwarfCU* last_cu() const {
+ return last_cu_;
+ }
+
+ /* Gets number of compilation units, collected during parsing of
+ * this ELF file with parse_compilation_units() method.
+ */
+ int cu_count() const {
+ return cu_count_;
+ }
+
+ /* Gets executable file flag */
+ bool is_exec() const {
+ return is_exec_;
+ }
+
+ protected:
+ /* Initializes ElfFile instance. This method is called from Create method of
+ * this class after appropriate ElfFileImpl instance has been created. Note,
+ * that Create() method will validate that requested file is an ELF file,
+ * prior to instantiating of an ElfFileImpl object, and calling this method.
+ * Param:
+ * elf_hdr - Address of the common ELF file header.
+ * path - See Create().
+ * Return:
+ * true on success, or false on failure, with errno containing extended
+ * error information.
+ */
+ virtual bool initialize(const Elf_CommonHdr* elf_hdr, const char* path);
+
+/*=============================================================================
+ * Endianness helper methods.
+ * Since endianness of ELF file may differ from the endianness of the CPU this
+ * library runs on, every time a value is required from a section of the ELF
+ * file, it must be first pulled out of that section to a local variable, and
+ * then used from that local variable. While value is pulled from ELF file
+ * section, it must be converted accordingly to the endianness of the CPU and
+ * ELF file. Routines bellow provide such functionality.
+=============================================================================*/
+
+ public:
+ /* Pulls one byte value from ELF file. Note that for one byte we don't need
+ * to do any endianness conversion, and these two methods are provided purely
+ * for completness of the API.
+ * Param:
+ * val - References value inside ELF file buffer to pull data from.
+ * Return
+ * Pulled value with endianness appropriate for the CPU this library is
+ * running on.
+ */
+ uint8_t pull_val(const uint8_t* val) const {
+ return *val;
+ }
+ uint8_t pull_val(const uint8_t& val) const {
+ return val;
+ }
+ int8_t pull_val(const int8_t* val) const {
+ return *val;
+ }
+ int8_t pull_val(const int8_t& val) const {
+ return val;
+ }
+
+ /* Pulls two byte value from ELF file.
+ * Param:
+ * val - References value inside ELF file buffer to pull data from.
+ * Return
+ * Pulled value with endianness appropriate for the CPU this library is
+ * running on.
+ */
+ uint16_t pull_val(const uint16_t* val) const {
+ if (same_endianness()) {
+ return *val;
+ }
+ if (is_elf_big_endian()) {
+ return (uint16_t)get_byte(val, 0) << 8 | get_byte(val, 1);
+ } else {
+ return (uint16_t)get_byte(val, 1) << 8 | get_byte(val, 0);
+ }
+ }
+ uint16_t pull_val(const uint16_t& val) const {
+ return same_endianness() ? val : pull_val(&val);
+ }
+ int16_t pull_val(const int16_t* val) const {
+ return static_cast<int16_t>
+ (pull_val(reinterpret_cast<const uint16_t*>(val)));
+ }
+ int16_t pull_val(const int16_t& val) const {
+ return static_cast<int16_t>
+ (pull_val(reinterpret_cast<const uint16_t&>(val)));
+ }
+
+ /* Pulls four byte value from ELF file.
+ * Param:
+ * val - References value inside ELF file buffer to pull data from.
+ * Return
+ * Pulled value with endianness appropriate for the CPU this library is
+ * running on.
+ */
+ uint32_t pull_val(const uint32_t* val) const {
+ if (same_endianness()) {
+ return *val;
+ }
+ if (is_elf_big_endian()) {
+ return (uint32_t)get_byte(val, 0) << 24 |
+ (uint32_t)get_byte(val, 1) << 16 |
+ (uint32_t)get_byte(val, 2) << 8 |
+ (uint32_t)get_byte(val, 3);
+ } else {
+ return (uint32_t)get_byte(val, 3) << 24 |
+ (uint32_t)get_byte(val, 2) << 16 |
+ (uint32_t)get_byte(val, 1) << 8 |
+ (uint32_t)get_byte(val, 0);
+ }
+ }
+ uint32_t pull_val(const uint32_t& val) const {
+ return same_endianness() ? val : pull_val(&val);
+ }
+ int32_t pull_val(const int32_t* val) const {
+ return static_cast<int32_t>
+ (pull_val(reinterpret_cast<const uint32_t*>(val)));
+ }
+ int32_t pull_val(const int32_t& val) const {
+ return static_cast<int32_t>
+ (pull_val(reinterpret_cast<const uint32_t&>(val)));
+ }
+
+ /* Pulls eight byte value from ELF file.
+ * Param:
+ * val - References value inside ELF file buffer to pull data from.
+ * Return
+ * Pulled value with endianness appropriate for the CPU this library is
+ * running on.
+ */
+ uint64_t pull_val(const uint64_t* val) const {
+ if (same_endianness()) {
+ return *val;
+ }
+ if (is_elf_big_endian()) {
+ return (uint64_t)get_byte(val, 0) << 56 |
+ (uint64_t)get_byte(val, 1) << 48 |
+ (uint64_t)get_byte(val, 2) << 40 |
+ (uint64_t)get_byte(val, 3) << 32 |
+ (uint64_t)get_byte(val, 4) << 24 |
+ (uint64_t)get_byte(val, 5) << 16 |
+ (uint64_t)get_byte(val, 6) << 8 |
+ (uint64_t)get_byte(val, 7);
+ } else {
+ return (uint64_t)get_byte(val, 7) << 56 |
+ (uint64_t)get_byte(val, 6) << 48 |
+ (uint64_t)get_byte(val, 5) << 40 |
+ (uint64_t)get_byte(val, 4) << 32 |
+ (uint64_t)get_byte(val, 3) << 24 |
+ (uint64_t)get_byte(val, 2) << 16 |
+ (uint64_t)get_byte(val, 1) << 8 |
+ (uint64_t)get_byte(val, 0);
+ }
+ }
+ uint64_t pull_val(const uint64_t& val) const {
+ return same_endianness() ? val : pull_val(&val);
+ }
+ int64_t pull_val(const int64_t* val) const {
+ return static_cast<int64_t>
+ (pull_val(reinterpret_cast<const uint64_t*>(val)));
+ }
+ int64_t pull_val(const int64_t& val) const {
+ return static_cast<int64_t>
+ (pull_val(reinterpret_cast<const uint64_t&>(val)));
+ }
+
+//=============================================================================
+// ELF file section management.
+//=============================================================================
+
+ public:
+ /* Gets a string contained in ELF's string section by index.
+ * Param:
+ * index - String index (byte offset) in the ELF's string section.
+ * Return:
+ * Pointer to the requested string, or NULL if string index exceeds ELF's
+ * string section size.
+ * NOTE: pointer returned from this method points to a mapped section of
+ * ELF file.
+ */
+ const char* get_str_sec_str(Elf_Xword index) const {
+ assert(string_section_.is_mapped() && index < string_section_.size());
+ if (string_section_.is_mapped() && index < string_section_.size()) {
+ return INC_CPTR_T(char, string_section_.data(), index);
+ } else {
+ _set_errno(EINVAL);
+ return NULL;
+ }
+ }
+
+ /* Gets a string contained in ELF's debug string section (.debug_str)
+ * by index.
+ * Param:
+ * index - String index (byte offset) in the ELF's debug string section.
+ * Return:
+ * Pointer to the requested string, or NULL if string index exceeds ELF's
+ * debug string section size.
+ * NOTE: pointer returned from this method points to a mapped section of
+ * ELF file.
+ */
+ const char* get_debug_str(Elf_Xword index) const {
+ assert(debug_str_.is_mapped() && index < debug_str_.size());
+ if (debug_str_.is_mapped() && index < debug_str_.size()) {
+ return INC_CPTR_T(char, debug_str_.data(), index);
+ } else {
+ _set_errno(EINVAL);
+ return NULL;
+ }
+ }
+
+ protected:
+ /* Gets pointer to a section header, given section index within ELF's
+ * section table.
+ * Param:
+ * index - Section index within ELF's section table.
+ * Return:
+ * Pointer to a section header (ElfXX_SHdr flavor, depending on ELF's CPU
+ * architecture) on success, or NULL if section index exceeds number of
+ * sections for this ELF file.
+ */
+ const void* get_section_by_index(Elf_Half index) const {
+ assert(index < sec_count_);
+ if (index < sec_count_) {
+ return INC_CPTR(sec_table_, static_cast<size_t>(index) * sec_entry_size_);
+ } else {
+ _set_errno(EINVAL);
+ return NULL;
+ }
+ }
+
+//=============================================================================
+// DWARF management.
+//=============================================================================
+
+ protected:
+ /* Parses DWARF, and buids a list of compilation units for this ELF file.
+ * Compilation unit, collected with this methods are linked together in a
+ * list, head of which is available via last_cu() method of this class.
+ * NOTE: CUs in the list returned via last_cu() method are in reverse order
+ * relatively to the order in which CUs are stored in .debug_info section.
+ * This is ELF and DWARF data format - dependent method.
+ * Param:
+ * parse_context - Parsing context that defines which tags, and which
+ * properties for which tag should be collected during parsing. NULL
+ * passed in this parameter indicates that all properties for all tags
+ * should be collected.
+ * Return:
+ * Number of compilation units, collected in this method on success,
+ * or -1 on failure.
+ */
+ virtual int parse_compilation_units(const DwarfParseContext* parse_context) = 0;
+
+ public:
+ /* Gets PC address information.
+ * Param:
+ * address - PC address to get information for. The address must be relative
+ * to the beginning of ELF file represented by this class.
+ * address_info - Upon success contains information about routine(s) that
+ * contain the given address.
+ * Return:
+ * true if routine(s) containing has been found and its information has been
+ * saved into address_info, or false if no appropriate routine for that
+ * address has been found, or there was a memory error when collecting
+ * routine(s) information. In case of failure, errno contains extended error
+ * information.
+ */
+ bool get_pc_address_info(Elf_Xword address, Elf_AddressInfo* address_info);
+
+ /* Frees resources aqcuired for address information in successful call to
+ * get_pc_address_info().
+ * Param:
+ * address_info - Address information structure, initialized in successful
+ * call to get_pc_address_info() routine.
+ */
+ void free_pc_address_info(Elf_AddressInfo* address_info) const;
+
+ /* Gets beginning of the .debug_info section data.
+ * Return:
+ * Beginning of the .debug_info section data.
+ * NOTE: pointer returned from this method points to a mapped section of
+ * ELF file.
+ */
+ const void* get_debug_info_data() const {
+ return debug_info_.data();
+ }
+
+ /* Gets beginning of the .debug_abbrev section data.
+ * Return:
+ * Beginning of the .debug_abbrev section data.
+ * NOTE: pointer returned from this method points to a mapped section of
+ * ELF file.
+ */
+ const void* get_debug_abbrev_data() const {
+ return debug_abbrev_.data();
+ }
+
+ /* Gets beginning of the .debug_ranges section data.
+ * Return:
+ * Beginning of the .debug_ranges section data.
+ * NOTE: pointer returned from this method points to a mapped section of
+ * ELF file.
+ */
+ const void* get_debug_ranges_data() const {
+ return debug_ranges_.data();
+ }
+
+ /* Gets beginning of the .debug_line section data.
+ * Return:
+ * Beginning of the .debug_line section data.
+ * NOTE: pointer returned from this method points to a mapped section of
+ * ELF file.
+ */
+ const void* get_debug_line_data() const {
+ return debug_line_.data();
+ }
+
+ /* Checks, if given address range is contained in the mapped .debug_info
+ * section of this file.
+ * Param:
+ * ptr - Starting address of the range.
+ * size - Range size in bytes.
+ * Return:
+ * true if given address range is contained in the mapped .debug_info
+ * section of this file, or false if any part of the range doesn't belong
+ * to that section.
+ */
+ bool is_valid_die_ptr(const void* ptr, size_t size) const {
+ return debug_info_.is_contained(ptr, size);
+ }
+
+ /* Checks, if given address range is contained in the mapped .debug_abbrev
+ * section of this file.
+ * Param:
+ * ptr - Starting address of the range.
+ * size - Range size in bytes.
+ * Return:
+ * true if given address range is contained in the mapped .debug_abbrev
+ * section of this file, or false if any part of the range doesn't belong
+ * to that section.
+ */
+ bool is_valid_abbr_ptr(const void* ptr, size_t size) const {
+ return debug_abbrev_.is_contained(ptr, size);
+ }
+
+ /* Checks if given pointer addresses a valid compilation unit header in the
+ * mapped .debug_info section of the ELF file.
+ * Param:
+ * cu_header - Pointer to a compilation unit header to check.
+ * Return
+ * true, if given pointer addresses a valid compilation unit header, or
+ * false, if it's not. A valid CU header must be fully conained inside
+ * .debug_info section of the ELF file, and its size must not be zero.
+ */
+ bool is_valid_cu(const void* cu_header) const {
+ if (is_DWARF_64()) {
+ return is_valid_die_ptr(cu_header, sizeof(Dwarf64_CUHdr)) &&
+ reinterpret_cast<const Dwarf64_CUHdr*>(cu_header)->size_hdr.size != 0;
+ } else {
+ return is_valid_die_ptr(cu_header, sizeof(Dwarf32_CUHdr)) &&
+ reinterpret_cast<const Dwarf32_CUHdr*>(cu_header)->size_hdr.size != 0;
+ }
+ }
+
+ /* Gets range's low and high pc for the given range reference in the mapped
+ * .debug_ranges section of an ELF file.
+ * Template param:
+ * AddrType - Defines pointer type for the CU the range belongs to. CU's
+ * pointer type can be defined independently from ELF and DWARF types,
+ * and is encoded in address_size field of the CU header in .debug_info
+ * section of ELF file.
+ * Param:
+ * offset - Byte offset within .debug_ranges section of the range record.
+ * low - Upon successful return contains value for range's low pc.
+ * high - Upon successful return contains value for range's high pc.
+ * Return:
+ * true on success, or false, if requested record is not fully contained
+ * in the .debug_ranges section.
+ */
+ template<typename AddrType>
+ bool get_range(Elf_Word offset, AddrType* low, AddrType* high) {
+ const AddrType* ptr = INC_CPTR_T(AddrType, debug_ranges_.data(), offset);
+ assert(debug_ranges_.is_contained(ptr, sizeof(AddrType) * 2));
+ if (!debug_ranges_.is_contained(ptr, sizeof(AddrType) * 2)) {
+ _set_errno(EINVAL);
+ return false;
+ }
+ *low = pull_val(ptr);
+ *high = pull_val(ptr + 1);
+ return true;
+ }
+
+ protected:
+ /* Mapped ELF string section. */
+ ElfMappedSection string_section_;
+
+ /* Mapped .debug_info section. */
+ ElfMappedSection debug_info_;
+
+ /* Mapped .debug_abbrev section. */
+ ElfMappedSection debug_abbrev_;
+
+ /* Mapped .debug_str section. */
+ ElfMappedSection debug_str_;
+
+ /* Mapped .debug_line section. */
+ ElfMappedSection debug_line_;
+
+ /* Mapped .debug_ranges section. */
+ ElfMappedSection debug_ranges_;
+
+ /* Base address of the loaded module (if fixed), or 0 if module doesn't get
+ * loaded at fixed address. */
+ Elf_Xword fixed_base_address_;
+
+ /* Handle to the ELF file represented with this instance. */
+ ELF_FILE_HANDLE elf_handle_;
+
+ /* Path to the ELF file represented with this instance. */
+ char* elf_file_path_;
+
+ /* DWARF objects allocator for this instance. */
+ class ElfAllocator* allocator_;
+
+ /* Beginning of the cached ELF's section table. */
+ void* sec_table_;
+
+ /* Number of sections in the ELF file wrapped by this instance. */
+ Elf_Half sec_count_;
+
+ /* Byte size of an entry in the section table. */
+ Elf_Half sec_entry_size_;
+
+ /* Head of compilation unit list, collected during the parsing. */
+ class DwarfCU* last_cu_;
+
+ /* Number of compilation units in last_cu_ list. */
+ int cu_count_;
+
+ /* Flags ELF's CPU architecture: 64 (true), or 32 bits (false). */
+ bool is_ELF_64_;
+
+ /* Flags endianness of the processed ELF file. true indicates that ELF file
+ * data is stored in big-endian form, false indicates that ELF file data is
+ * stored in big-endian form.
+ */
+ bool is_elf_big_endian_;
+
+ /* Flags whether or not endianness of CPU this library is built for matches
+ * endianness of the ELF file that is represented with this instance.
+ */
+ bool same_endianness_;
+
+ /* Flags DWARF format: 64, or 32 bits. DWARF format is determined by looking
+ * at the first 4 bytes of .debug_info section (which is the beginning of the
+ * first compilation unit header). If first 4 bytes contain 0xFFFFFFFF, the
+ * DWARF is 64 bit. Otherwise, DWARF is 32 bit. */
+ bool is_DWARF_64_;
+
+ /* Flags executable file. If this member is 1, ELF file represented with this
+ * instance is an executable. If this member is 0, file is a shared library.
+ */
+ bool is_exec_;
+};
+
+/* Encapsulates architecture-dependent functionality of an ELF file.
+ * Template param:
+ * Elf_Addr - type for an address field in ELF file. Must be:
+ * - Elf32_Addr for 32-bit CPU, or
+ * - Elf64_Addr for 64-bit CPU.
+ * Elf_Off - type for an offset field in ELF file. Must be:
+ * - Elf64_Off for 32-bit CPU, or
+ * - Elf64_Off for 64-bit CPU.
+ */
+template <typename Elf_Addr, typename Elf_Off>
+class ElfFileImpl : protected ElfFile {
+/* Instance of this class must be instantiated from
+ * ElfFile::Create() method only. */
+friend class ElfFile;
+ protected:
+ /* Constructs ElfFileImpl instance. */
+ ElfFileImpl() {
+ };
+
+ /* Destructs ElfFileImpl instance. */
+ ~ElfFileImpl() {
+ }
+
+ protected:
+ /* Initializes instance. This is an override of the base class method.
+ * See ElfFile::initialize().
+ */
+ bool initialize(const Elf_CommonHdr* elf_hdr, const char* path);
+
+ /* Parses DWARF, and buids list of compilation units for this ELF file.
+ * This is an implementation of the base class' abstract method.
+ * See ElfFile::parse_compilation_units().
+ */
+ virtual int parse_compilation_units(const DwarfParseContext* parse_context);
+
+ /* Gets section information by section name.
+ * Param:
+ * name - Name of the section to get information for.
+ * offset - Upon success contains offset of the section data in ELF file.
+ * size - Upon success contains size of the section data in ELF file.
+ * Return:
+ * true on sucess, or false if section with such name doesn't exist in
+ * this ELF file.
+ */
+ bool get_section_info_by_name(const char* name,
+ Elf_Off* offset,
+ Elf_Word* size);
+
+ /* Maps section by its name.
+ * Param:
+ * name - Name of the section to map.
+ * section - Upon success contains section's mapping information.
+ * Return:
+ * true on sucess, or false if section with such name doesn't exist in
+ * this ELF file, or mapping has failed.
+ */
+ bool map_section_by_name(const char* name, ElfMappedSection* section);
+};
+
+#endif // ELFF_ELF_FILE_H_
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