| // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "courgette/disassembler_win32_x86.h" |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <algorithm> |
| #include <string> |
| #include <vector> |
| |
| #include "base/logging.h" |
| |
| #include "courgette/assembly_program.h" |
| #include "courgette/courgette.h" |
| #include "courgette/encoded_program.h" |
| #include "courgette/rel32_finder_win32_x86.h" |
| |
| namespace courgette { |
| |
| DisassemblerWin32X86::DisassemblerWin32X86(const void* start, size_t length) |
| : Disassembler(start, length), |
| incomplete_disassembly_(false), |
| is_PE32_plus_(false), |
| optional_header_(NULL), |
| size_of_optional_header_(0), |
| offset_of_data_directories_(0), |
| machine_type_(0), |
| number_of_sections_(0), |
| sections_(NULL), |
| has_text_section_(false), |
| size_of_code_(0), |
| size_of_initialized_data_(0), |
| size_of_uninitialized_data_(0), |
| base_of_code_(0), |
| base_of_data_(0), |
| image_base_(0), |
| size_of_image_(0), |
| number_of_data_directories_(0) { |
| } |
| |
| // ParseHeader attempts to match up the buffer with the Windows data |
| // structures that exist within a Windows 'Portable Executable' format file. |
| // Returns 'true' if the buffer matches, and 'false' if the data looks |
| // suspicious. Rather than try to 'map' the buffer to the numerous windows |
| // structures, we extract the information we need into the courgette::PEInfo |
| // structure. |
| // |
| bool DisassemblerWin32X86::ParseHeader() { |
| if (length() < kOffsetOfFileAddressOfNewExeHeader + 4 /*size*/) |
| return Bad("Too small"); |
| |
| // Have 'MZ' magic for a DOS header? |
| if (start()[0] != 'M' || start()[1] != 'Z') |
| return Bad("Not MZ"); |
| |
| // offset from DOS header to PE header is stored in DOS header. |
| uint32_t offset = ReadU32(start(), kOffsetOfFileAddressOfNewExeHeader); |
| |
| if (offset >= length()) |
| return Bad("Bad offset to PE header"); |
| |
| const uint8_t* const pe_header = OffsetToPointer(offset); |
| const size_t kMinPEHeaderSize = 4 /*signature*/ + kSizeOfCoffHeader; |
| if (pe_header <= start() || |
| pe_header >= end() - kMinPEHeaderSize) |
| return Bad("Bad offset to PE header"); |
| |
| if (offset % 8 != 0) |
| return Bad("Misaligned PE header"); |
| |
| // The 'PE' header is an IMAGE_NT_HEADERS structure as defined in WINNT.H. |
| // See http://msdn.microsoft.com/en-us/library/ms680336(VS.85).aspx |
| // |
| // The first field of the IMAGE_NT_HEADERS is the signature. |
| if (!(pe_header[0] == 'P' && |
| pe_header[1] == 'E' && |
| pe_header[2] == 0 && |
| pe_header[3] == 0)) |
| return Bad("no PE signature"); |
| |
| // The second field of the IMAGE_NT_HEADERS is the COFF header. |
| // The COFF header is also called an IMAGE_FILE_HEADER |
| // http://msdn.microsoft.com/en-us/library/ms680313(VS.85).aspx |
| const uint8_t* const coff_header = pe_header + 4; |
| machine_type_ = ReadU16(coff_header, 0); |
| number_of_sections_ = ReadU16(coff_header, 2); |
| size_of_optional_header_ = ReadU16(coff_header, 16); |
| |
| // The rest of the IMAGE_NT_HEADERS is the IMAGE_OPTIONAL_HEADER(32|64) |
| const uint8_t* const optional_header = coff_header + kSizeOfCoffHeader; |
| optional_header_ = optional_header; |
| |
| if (optional_header + size_of_optional_header_ >= end()) |
| return Bad("optional header past end of file"); |
| |
| // Check we can read the magic. |
| if (size_of_optional_header_ < 2) |
| return Bad("optional header no magic"); |
| |
| uint16_t magic = ReadU16(optional_header, 0); |
| |
| if (magic == kImageNtOptionalHdr32Magic) { |
| is_PE32_plus_ = false; |
| offset_of_data_directories_ = |
| kOffsetOfDataDirectoryFromImageOptionalHeader32; |
| } else if (magic == kImageNtOptionalHdr64Magic) { |
| is_PE32_plus_ = true; |
| offset_of_data_directories_ = |
| kOffsetOfDataDirectoryFromImageOptionalHeader64; |
| } else { |
| return Bad("unrecognized magic"); |
| } |
| |
| // Check that we can read the rest of the the fixed fields. Data directories |
| // directly follow the fixed fields of the IMAGE_OPTIONAL_HEADER. |
| if (size_of_optional_header_ < offset_of_data_directories_) |
| return Bad("optional header too short"); |
| |
| // The optional header is either an IMAGE_OPTIONAL_HEADER32 or |
| // IMAGE_OPTIONAL_HEADER64 |
| // http://msdn.microsoft.com/en-us/library/ms680339(VS.85).aspx |
| // |
| // Copy the fields we care about. |
| size_of_code_ = ReadU32(optional_header, 4); |
| size_of_initialized_data_ = ReadU32(optional_header, 8); |
| size_of_uninitialized_data_ = ReadU32(optional_header, 12); |
| base_of_code_ = ReadU32(optional_header, 20); |
| if (is_PE32_plus_) { |
| base_of_data_ = 0; |
| image_base_ = ReadU64(optional_header, 24); |
| } else { |
| base_of_data_ = ReadU32(optional_header, 24); |
| image_base_ = ReadU32(optional_header, 28); |
| } |
| size_of_image_ = ReadU32(optional_header, 56); |
| number_of_data_directories_ = |
| ReadU32(optional_header, (is_PE32_plus_ ? 108 : 92)); |
| |
| if (size_of_code_ >= length() || |
| size_of_initialized_data_ >= length() || |
| size_of_code_ + size_of_initialized_data_ >= length()) { |
| // This validation fires on some perfectly fine executables. |
| // return Bad("code or initialized data too big"); |
| } |
| |
| // TODO(sra): we can probably get rid of most of the data directories. |
| bool b = true; |
| // 'b &= ...' could be short circuit 'b = b && ...' but it is not necessary |
| // for correctness and it compiles smaller this way. |
| b &= ReadDataDirectory(0, &export_table_); |
| b &= ReadDataDirectory(1, &import_table_); |
| b &= ReadDataDirectory(2, &resource_table_); |
| b &= ReadDataDirectory(3, &exception_table_); |
| b &= ReadDataDirectory(5, &base_relocation_table_); |
| b &= ReadDataDirectory(11, &bound_import_table_); |
| b &= ReadDataDirectory(12, &import_address_table_); |
| b &= ReadDataDirectory(13, &delay_import_descriptor_); |
| b &= ReadDataDirectory(14, &clr_runtime_header_); |
| if (!b) { |
| return Bad("malformed data directory"); |
| } |
| |
| // Sections follow the optional header. |
| sections_ = |
| reinterpret_cast<const Section*>(optional_header + |
| size_of_optional_header_); |
| size_t detected_length = 0; |
| |
| for (int i = 0; i < number_of_sections_; ++i) { |
| const Section* section = §ions_[i]; |
| |
| // TODO(sra): consider using the 'characteristics' field of the section |
| // header to see if the section contains instructions. |
| if (memcmp(section->name, ".text", 6) == 0) |
| has_text_section_ = true; |
| |
| uint32_t section_end = |
| section->file_offset_of_raw_data + section->size_of_raw_data; |
| if (section_end > detected_length) |
| detected_length = section_end; |
| } |
| |
| // Pretend our in-memory copy is only as long as our detected length. |
| ReduceLength(detected_length); |
| |
| if (!is_32bit()) { |
| return Bad("64 bit executables are not supported by this disassembler"); |
| } |
| |
| if (!has_text_section()) { |
| return Bad("Resource-only executables are not yet supported"); |
| } |
| |
| return Good(); |
| } |
| |
| bool DisassemblerWin32X86::Disassemble(AssemblyProgram* target) { |
| if (!ok()) |
| return false; |
| |
| target->set_image_base(image_base()); |
| |
| if (!ParseAbs32Relocs()) |
| return false; |
| |
| ParseRel32RelocsFromSections(); |
| |
| if (!ParseFile(target)) |
| return false; |
| |
| target->DefaultAssignIndexes(); |
| |
| return true; |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| bool DisassemblerWin32X86::ParseRelocs(std::vector<RVA> *relocs) { |
| relocs->clear(); |
| |
| size_t relocs_size = base_relocation_table_.size_; |
| if (relocs_size == 0) |
| return true; |
| |
| // The format of the base relocation table is a sequence of variable sized |
| // IMAGE_BASE_RELOCATION blocks. Search for |
| // "The format of the base relocation data is somewhat quirky" |
| // at http://msdn.microsoft.com/en-us/library/ms809762.aspx |
| |
| const uint8_t* relocs_start = RVAToPointer(base_relocation_table_.address_); |
| const uint8_t* relocs_end = relocs_start + relocs_size; |
| |
| // Make sure entire base relocation table is within the buffer. |
| if (relocs_start < start() || |
| relocs_start >= end() || |
| relocs_end <= start() || |
| relocs_end > end()) { |
| return Bad(".relocs outside image"); |
| } |
| |
| const uint8_t* block = relocs_start; |
| |
| // Walk the variable sized blocks. |
| while (block + 8 < relocs_end) { |
| RVA page_rva = ReadU32(block, 0); |
| uint32_t size = ReadU32(block, 4); |
| if (size < 8 || // Size includes header ... |
| size % 4 != 0) // ... and is word aligned. |
| return Bad("unreasonable relocs block"); |
| |
| const uint8_t* end_entries = block + size; |
| |
| if (end_entries <= block || |
| end_entries <= start() || |
| end_entries > end()) |
| return Bad(".relocs block outside image"); |
| |
| // Walk through the two-byte entries. |
| for (const uint8_t* p = block + 8; p < end_entries; p += 2) { |
| uint16_t entry = ReadU16(p, 0); |
| int type = entry >> 12; |
| int offset = entry & 0xFFF; |
| |
| RVA rva = page_rva + offset; |
| // Skip the relocs that live outside of the image. It might be the case |
| // if a reloc is relative to a register, e.g.: |
| // mov ecx,dword ptr [eax+044D5888h] |
| uint32_t target_address = Read32LittleEndian(RVAToPointer(rva)); |
| if (target_address < image_base_ || |
| target_address > (image_base_ + size_of_image_)) { |
| continue; |
| } |
| if (type == 3) { // IMAGE_REL_BASED_HIGHLOW |
| relocs->push_back(rva); |
| } else if (type == 0) { // IMAGE_REL_BASED_ABSOLUTE |
| // Ignore, used as padding. |
| } else { |
| // Does not occur in Windows x86 executables. |
| return Bad("unknown type of reloc"); |
| } |
| } |
| |
| block += size; |
| } |
| |
| std::sort(relocs->begin(), relocs->end()); |
| DCHECK(relocs->empty() || relocs->back() != kUnassignedRVA); |
| |
| return true; |
| } |
| |
| const Section* DisassemblerWin32X86::RVAToSection(RVA rva) const { |
| for (int i = 0; i < number_of_sections_; i++) { |
| const Section* section = §ions_[i]; |
| uint32_t offset = rva - section->virtual_address; |
| if (offset < section->virtual_size) { |
| return section; |
| } |
| } |
| return NULL; |
| } |
| |
| int DisassemblerWin32X86::RVAToFileOffset(RVA rva) const { |
| const Section* section = RVAToSection(rva); |
| if (section) { |
| uint32_t offset = rva - section->virtual_address; |
| if (offset < section->size_of_raw_data) { |
| return section->file_offset_of_raw_data + offset; |
| } else { |
| return kNoOffset; // In section but not in file (e.g. uninit data). |
| } |
| } |
| |
| // Small RVA values point into the file header in the loaded image. |
| // RVA 0 is the module load address which Windows uses as the module handle. |
| // RVA 2 sometimes occurs, I'm not sure what it is, but it would map into the |
| // DOS header. |
| if (rva == 0 || rva == 2) |
| return rva; |
| |
| NOTREACHED(); |
| return kNoOffset; |
| } |
| |
| const uint8_t* DisassemblerWin32X86::RVAToPointer(RVA rva) const { |
| int file_offset = RVAToFileOffset(rva); |
| if (file_offset == kNoOffset) |
| return NULL; |
| else |
| return OffsetToPointer(file_offset); |
| } |
| |
| std::string DisassemblerWin32X86::SectionName(const Section* section) { |
| if (section == NULL) |
| return "<none>"; |
| char name[9]; |
| memcpy(name, section->name, 8); |
| name[8] = '\0'; // Ensure termination. |
| return name; |
| } |
| |
| CheckBool DisassemblerWin32X86::ParseFile(AssemblyProgram* program) { |
| // Walk all the bytes in the file, whether or not in a section. |
| uint32_t file_offset = 0; |
| while (file_offset < length()) { |
| const Section* section = FindNextSection(file_offset); |
| if (section == NULL) { |
| // No more sections. There should not be extra stuff following last |
| // section. |
| // ParseNonSectionFileRegion(file_offset, pe_info().length(), program); |
| break; |
| } |
| if (file_offset < section->file_offset_of_raw_data) { |
| uint32_t section_start_offset = section->file_offset_of_raw_data; |
| if(!ParseNonSectionFileRegion(file_offset, section_start_offset, |
| program)) |
| return false; |
| |
| file_offset = section_start_offset; |
| } |
| uint32_t end = file_offset + section->size_of_raw_data; |
| if (!ParseFileRegion(section, file_offset, end, program)) |
| return false; |
| file_offset = end; |
| } |
| |
| #if COURGETTE_HISTOGRAM_TARGETS |
| HistogramTargets("abs32 relocs", abs32_target_rvas_); |
| HistogramTargets("rel32 relocs", rel32_target_rvas_); |
| #endif |
| |
| return true; |
| } |
| |
| bool DisassemblerWin32X86::ParseAbs32Relocs() { |
| abs32_locations_.clear(); |
| if (!ParseRelocs(&abs32_locations_)) |
| return false; |
| |
| #if COURGETTE_HISTOGRAM_TARGETS |
| for (size_t i = 0; i < abs32_locations_.size(); ++i) { |
| RVA rva = abs32_locations_[i]; |
| // The 4 bytes at the relocation are a reference to some address. |
| uint32_t target_address = Read32LittleEndian(RVAToPointer(rva)); |
| ++abs32_target_rvas_[target_address - image_base()]; |
| } |
| #endif |
| return true; |
| } |
| |
| void DisassemblerWin32X86::ParseRel32RelocsFromSections() { |
| uint32_t file_offset = 0; |
| while (file_offset < length()) { |
| const Section* section = FindNextSection(file_offset); |
| if (section == NULL) |
| break; |
| if (file_offset < section->file_offset_of_raw_data) |
| file_offset = section->file_offset_of_raw_data; |
| ParseRel32RelocsFromSection(section); |
| file_offset += section->size_of_raw_data; |
| } |
| std::sort(rel32_locations_.begin(), rel32_locations_.end()); |
| DCHECK(rel32_locations_.empty() || |
| rel32_locations_.back() != kUnassignedRVA); |
| |
| #if COURGETTE_HISTOGRAM_TARGETS |
| VLOG(1) << "abs32_locations_ " << abs32_locations_.size() |
| << "\nrel32_locations_ " << rel32_locations_.size() |
| << "\nabs32_target_rvas_ " << abs32_target_rvas_.size() |
| << "\nrel32_target_rvas_ " << rel32_target_rvas_.size(); |
| |
| int common = 0; |
| std::map<RVA, int>::iterator abs32_iter = abs32_target_rvas_.begin(); |
| std::map<RVA, int>::iterator rel32_iter = rel32_target_rvas_.begin(); |
| while (abs32_iter != abs32_target_rvas_.end() && |
| rel32_iter != rel32_target_rvas_.end()) { |
| if (abs32_iter->first < rel32_iter->first) |
| ++abs32_iter; |
| else if (rel32_iter->first < abs32_iter->first) |
| ++rel32_iter; |
| else { |
| ++common; |
| ++abs32_iter; |
| ++rel32_iter; |
| } |
| } |
| VLOG(1) << "common " << common; |
| #endif |
| } |
| |
| void DisassemblerWin32X86::ParseRel32RelocsFromSection(const Section* section) { |
| // TODO(sra): use characteristic. |
| bool isCode = strcmp(section->name, ".text") == 0; |
| if (!isCode) |
| return; |
| |
| uint32_t start_file_offset = section->file_offset_of_raw_data; |
| uint32_t end_file_offset = start_file_offset + section->size_of_raw_data; |
| |
| const uint8_t* start_pointer = OffsetToPointer(start_file_offset); |
| const uint8_t* end_pointer = OffsetToPointer(end_file_offset); |
| |
| RVA start_rva = FileOffsetToRVA(start_file_offset); |
| RVA end_rva = start_rva + section->virtual_size; |
| |
| Rel32FinderWin32X86_Basic finder( |
| base_relocation_table().address_, |
| base_relocation_table().address_ + base_relocation_table().size_, |
| size_of_image_); |
| finder.Find(start_pointer, end_pointer, start_rva, end_rva, abs32_locations_); |
| finder.SwapRel32Locations(&rel32_locations_); |
| |
| #if COURGETTE_HISTOGRAM_TARGETS |
| DCHECK(rel32_target_rvas_.empty()); |
| finder.SwapRel32TargetRVAs(&rel32_target_rvas_); |
| #endif |
| } |
| |
| CheckBool DisassemblerWin32X86::ParseNonSectionFileRegion( |
| uint32_t start_file_offset, |
| uint32_t end_file_offset, |
| AssemblyProgram* program) { |
| if (incomplete_disassembly_) |
| return true; |
| |
| if (end_file_offset > start_file_offset) { |
| if (!program->EmitBytesInstruction(OffsetToPointer(start_file_offset), |
| end_file_offset - start_file_offset)) { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| CheckBool DisassemblerWin32X86::ParseFileRegion(const Section* section, |
| uint32_t start_file_offset, |
| uint32_t end_file_offset, |
| AssemblyProgram* program) { |
| RVA relocs_start_rva = base_relocation_table().address_; |
| |
| const uint8_t* start_pointer = OffsetToPointer(start_file_offset); |
| const uint8_t* end_pointer = OffsetToPointer(end_file_offset); |
| |
| RVA start_rva = FileOffsetToRVA(start_file_offset); |
| RVA end_rva = start_rva + section->virtual_size; |
| |
| // Quick way to convert from Pointer to RVA within a single Section is to |
| // subtract 'pointer_to_rva'. |
| const uint8_t* const adjust_pointer_to_rva = start_pointer - start_rva; |
| |
| std::vector<RVA>::iterator rel32_pos = rel32_locations_.begin(); |
| std::vector<RVA>::iterator abs32_pos = abs32_locations_.begin(); |
| |
| if (!program->EmitOriginInstruction(start_rva)) |
| return false; |
| |
| const uint8_t* p = start_pointer; |
| |
| while (p < end_pointer) { |
| RVA current_rva = static_cast<RVA>(p - adjust_pointer_to_rva); |
| |
| // The base relocation table is usually in the .relocs section, but it could |
| // actually be anywhere. Make sure we skip it because we will regenerate it |
| // during assembly. |
| if (current_rva == relocs_start_rva) { |
| if (!program->EmitPeRelocsInstruction()) |
| return false; |
| uint32_t relocs_size = base_relocation_table().size_; |
| if (relocs_size) { |
| p += relocs_size; |
| continue; |
| } |
| } |
| |
| while (abs32_pos != abs32_locations_.end() && *abs32_pos < current_rva) |
| ++abs32_pos; |
| |
| if (abs32_pos != abs32_locations_.end() && *abs32_pos == current_rva) { |
| uint32_t target_address = Read32LittleEndian(p); |
| RVA target_rva = target_address - image_base(); |
| // TODO(sra): target could be Label+offset. It is not clear how to guess |
| // which it might be. We assume offset==0. |
| if (!program->EmitAbs32(program->FindOrMakeAbs32Label(target_rva))) |
| return false; |
| p += 4; |
| continue; |
| } |
| |
| while (rel32_pos != rel32_locations_.end() && *rel32_pos < current_rva) |
| ++rel32_pos; |
| |
| if (rel32_pos != rel32_locations_.end() && *rel32_pos == current_rva) { |
| RVA target_rva = current_rva + 4 + Read32LittleEndian(p); |
| if (!program->EmitRel32(program->FindOrMakeRel32Label(target_rva))) |
| return false; |
| p += 4; |
| continue; |
| } |
| |
| if (incomplete_disassembly_) { |
| if ((abs32_pos == abs32_locations_.end() || end_rva <= *abs32_pos) && |
| (rel32_pos == rel32_locations_.end() || end_rva <= *rel32_pos) && |
| (end_rva <= relocs_start_rva || current_rva >= relocs_start_rva)) { |
| // No more relocs in this section, don't bother encoding bytes. |
| break; |
| } |
| } |
| |
| if (!program->EmitByteInstruction(*p)) |
| return false; |
| p += 1; |
| } |
| |
| return true; |
| } |
| |
| #if COURGETTE_HISTOGRAM_TARGETS |
| // Histogram is printed to std::cout. It is purely for debugging the algorithm |
| // and is only enabled manually in 'exploration' builds. I don't want to add |
| // command-line configuration for this feature because this code has to be |
| // small, which means compiled-out. |
| void DisassemblerWin32X86::HistogramTargets(const char* kind, |
| const std::map<RVA, int>& map) { |
| int total = 0; |
| std::map<int, std::vector<RVA> > h; |
| for (std::map<RVA, int>::const_iterator p = map.begin(); |
| p != map.end(); |
| ++p) { |
| h[p->second].push_back(p->first); |
| total += p->second; |
| } |
| |
| std::cout << total << " " << kind << " to " |
| << map.size() << " unique targets" << std::endl; |
| |
| std::cout << "indegree: #targets-with-indegree (example)" << std::endl; |
| const int kFirstN = 15; |
| bool someSkipped = false; |
| int index = 0; |
| for (std::map<int, std::vector<RVA> >::reverse_iterator p = h.rbegin(); |
| p != h.rend(); |
| ++p) { |
| ++index; |
| if (index <= kFirstN || p->first <= 3) { |
| if (someSkipped) { |
| std::cout << "..." << std::endl; |
| } |
| size_t count = p->second.size(); |
| std::cout << std::dec << p->first << ": " << count; |
| if (count <= 2) { |
| for (size_t i = 0; i < count; ++i) |
| std::cout << " " << DescribeRVA(p->second[i]); |
| } |
| std::cout << std::endl; |
| someSkipped = false; |
| } else { |
| someSkipped = true; |
| } |
| } |
| } |
| #endif // COURGETTE_HISTOGRAM_TARGETS |
| |
| |
| // DescribeRVA is for debugging only. I would put it under #ifdef DEBUG except |
| // that during development I'm finding I need to call it when compiled in |
| // Release mode. Hence: |
| // TODO(sra): make this compile only for debug mode. |
| std::string DisassemblerWin32X86::DescribeRVA(RVA rva) const { |
| const Section* section = RVAToSection(rva); |
| std::ostringstream s; |
| s << std::hex << rva; |
| if (section) { |
| s << " ("; |
| s << SectionName(section) << "+" |
| << std::hex << (rva - section->virtual_address) |
| << ")"; |
| } |
| return s.str(); |
| } |
| |
| const Section* DisassemblerWin32X86::FindNextSection( |
| uint32_t fileOffset) const { |
| const Section* best = 0; |
| for (int i = 0; i < number_of_sections_; i++) { |
| const Section* section = §ions_[i]; |
| if (section->size_of_raw_data > 0) { // i.e. has data in file. |
| if (fileOffset <= section->file_offset_of_raw_data) { |
| if (best == 0 || |
| section->file_offset_of_raw_data < best->file_offset_of_raw_data) { |
| best = section; |
| } |
| } |
| } |
| } |
| return best; |
| } |
| |
| RVA DisassemblerWin32X86::FileOffsetToRVA(uint32_t file_offset) const { |
| for (int i = 0; i < number_of_sections_; i++) { |
| const Section* section = §ions_[i]; |
| uint32_t offset = file_offset - section->file_offset_of_raw_data; |
| if (offset < section->size_of_raw_data) { |
| return section->virtual_address + offset; |
| } |
| } |
| return 0; |
| } |
| |
| bool DisassemblerWin32X86::ReadDataDirectory( |
| int index, |
| ImageDataDirectory* directory) { |
| |
| if (index < number_of_data_directories_) { |
| size_t offset = index * 8 + offset_of_data_directories_; |
| if (offset >= size_of_optional_header_) |
| return Bad("number of data directories inconsistent"); |
| const uint8_t* data_directory = optional_header_ + offset; |
| if (data_directory < start() || |
| data_directory + 8 >= end()) |
| return Bad("data directory outside image"); |
| RVA rva = ReadU32(data_directory, 0); |
| size_t size = ReadU32(data_directory, 4); |
| if (size > size_of_image_) |
| return Bad("data directory size too big"); |
| |
| // TODO(sra): validate RVA. |
| directory->address_ = rva; |
| directory->size_ = static_cast<uint32_t>(size); |
| return true; |
| } else { |
| directory->address_ = 0; |
| directory->size_ = 0; |
| return true; |
| } |
| } |
| |
| } // namespace courgette |