michael@0: #include "common/linux/synth_elf.h"
michael@0: 
michael@0: #include <assert.h>
michael@0: #include <elf.h>
michael@0: #include <stdio.h>
michael@0: #include <string.h>
michael@0: 
michael@0: #include "common/using_std_string.h"
michael@0: 
michael@0: namespace google_breakpad {
michael@0: namespace synth_elf {
michael@0: 
michael@0: #ifndef NT_GNU_BUILD_ID
michael@0: #define NT_GNU_BUILD_ID 3
michael@0: #endif
michael@0: 
michael@0: ELF::ELF(uint16_t machine,
michael@0:          uint8_t file_class,
michael@0:          Endianness endianness)
michael@0:   : Section(endianness),
michael@0:     addr_size_(file_class == ELFCLASS64 ? 8 : 4),
michael@0:     program_count_(0),
michael@0:     program_header_table_(endianness),
michael@0:     section_count_(0),
michael@0:     section_header_table_(endianness),
michael@0:     section_header_strings_(endianness) {
michael@0:   // Could add support for more machine types here if needed.
michael@0:   assert(machine == EM_386 ||
michael@0:          machine == EM_X86_64 ||
michael@0:          machine == EM_ARM);
michael@0:   assert(file_class == ELFCLASS32 || file_class == ELFCLASS64);
michael@0: 
michael@0:   start() = 0;
michael@0:   // Add ELF header
michael@0:   // e_ident
michael@0:   // EI_MAG0...EI_MAG3
michael@0:   D8(ELFMAG0);
michael@0:   D8(ELFMAG1);
michael@0:   D8(ELFMAG2);
michael@0:   D8(ELFMAG3);
michael@0:   // EI_CLASS
michael@0:   D8(file_class);
michael@0:   // EI_DATA
michael@0:   D8(endianness == kLittleEndian ? ELFDATA2LSB : ELFDATA2MSB);
michael@0:   // EI_VERSION
michael@0:   D8(EV_CURRENT);
michael@0:   // EI_OSABI
michael@0:   D8(ELFOSABI_SYSV);
michael@0:   // EI_ABIVERSION
michael@0:   D8(0);
michael@0:   // EI_PAD
michael@0:   Append(7, 0);
michael@0:   assert(Size() == EI_NIDENT);
michael@0: 
michael@0:   // e_type
michael@0:   D16(ET_EXEC);  //TODO: allow passing ET_DYN?
michael@0:   // e_machine
michael@0:   D16(machine);
michael@0:   // e_version
michael@0:   D32(EV_CURRENT);
michael@0:   // e_entry
michael@0:   Append(endianness, addr_size_, 0);
michael@0:   // e_phoff
michael@0:   Append(endianness, addr_size_, program_header_label_);
michael@0:   // e_shoff
michael@0:   Append(endianness, addr_size_, section_header_label_);
michael@0:   // e_flags
michael@0:   D32(0);
michael@0:   // e_ehsize
michael@0:   D16(addr_size_ == 8 ? sizeof(Elf64_Ehdr) : sizeof(Elf32_Ehdr));
michael@0:   // e_phentsize
michael@0:   D16(addr_size_ == 8 ? sizeof(Elf64_Phdr) : sizeof(Elf32_Phdr));
michael@0:   // e_phnum
michael@0:   D16(program_count_label_);
michael@0:   // e_shentsize
michael@0:   D16(addr_size_ == 8 ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr));
michael@0:   // e_shnum
michael@0:   D16(section_count_label_);
michael@0:   // e_shstrndx
michael@0:   D16(section_header_string_index_);
michael@0: 
michael@0:   // Add an empty section for SHN_UNDEF.
michael@0:   Section shn_undef;
michael@0:   AddSection("", shn_undef, SHT_NULL);
michael@0: }
michael@0: 
michael@0: int ELF::AddSection(const string& name, const Section& section,
michael@0:                     uint32_t type, uint32_t flags, uint64_t addr,
michael@0:                     uint32_t link, uint64_t entsize, uint64_t offset) {
michael@0:   Label offset_label;
michael@0:   Label string_label(section_header_strings_.Add(name));
michael@0:   size_t size = section.Size();
michael@0: 
michael@0:   int index = section_count_;
michael@0:   ++section_count_;
michael@0: 
michael@0:   section_header_table_
michael@0:     // sh_name
michael@0:     .D32(string_label)
michael@0:     // sh_type
michael@0:     .D32(type)
michael@0:     // sh_flags
michael@0:     .Append(endianness(), addr_size_, flags)
michael@0:     // sh_addr
michael@0:     .Append(endianness(), addr_size_, addr)
michael@0:     // sh_offset
michael@0:     .Append(endianness(), addr_size_, offset_label)
michael@0:     // sh_size
michael@0:     .Append(endianness(), addr_size_, size)
michael@0:     // sh_link
michael@0:     .D32(link)
michael@0:     // sh_info
michael@0:     .D32(0)
michael@0:     // sh_addralign
michael@0:     .Append(endianness(), addr_size_, 0)
michael@0:     // sh_entsize
michael@0:     .Append(endianness(), addr_size_, entsize);
michael@0: 
michael@0:   sections_.push_back(ElfSection(section, type, addr, offset, offset_label,
michael@0:                                  size));
michael@0:   return index;
michael@0: }
michael@0: 
michael@0: void ELF::AppendSection(ElfSection &section) {
michael@0:   // NULL and NOBITS sections have no content, so they
michael@0:   // don't need to be written to the file.
michael@0:   if (section.type_ == SHT_NULL) {
michael@0:     section.offset_label_ = 0;
michael@0:   } else if (section.type_ == SHT_NOBITS) {
michael@0:     section.offset_label_ = section.offset_;
michael@0:   } else {
michael@0:     Mark(&section.offset_label_);
michael@0:     Append(section);
michael@0:     Align(4);
michael@0:   }
michael@0: }
michael@0: 
michael@0: void ELF::AddSegment(int start, int end, uint32_t type, uint32_t flags) {
michael@0:   assert(start > 0);
michael@0:   assert(size_t(start) < sections_.size());
michael@0:   assert(end > 0);
michael@0:   assert(size_t(end) < sections_.size());
michael@0:   ++program_count_;
michael@0: 
michael@0:   // p_type
michael@0:   program_header_table_.D32(type);
michael@0: 
michael@0:   if (addr_size_ == 8) {
michael@0:     // p_flags
michael@0:     program_header_table_.D32(flags);
michael@0:   }
michael@0: 
michael@0:   size_t filesz = 0;
michael@0:   size_t memsz = 0;
michael@0:   bool prev_was_nobits = false;
michael@0:   for (int i = start; i <= end; ++i) {
michael@0:     size_t size = sections_[i].size_;
michael@0:     if (sections_[i].type_ != SHT_NOBITS) {
michael@0:       assert(!prev_was_nobits);
michael@0:       // non SHT_NOBITS sections are 4-byte aligned (see AddSection)
michael@0:       size = (size + 3) & ~3;
michael@0:       filesz += size;
michael@0:     } else {
michael@0:       prev_was_nobits = true;
michael@0:     }
michael@0:     memsz += size;
michael@0:   }
michael@0: 
michael@0:   program_header_table_
michael@0:     // p_offset
michael@0:     .Append(endianness(), addr_size_, sections_[start].offset_label_)
michael@0:     // p_vaddr
michael@0:     .Append(endianness(), addr_size_, sections_[start].addr_)
michael@0:     // p_paddr
michael@0:     .Append(endianness(), addr_size_, sections_[start].addr_)
michael@0:     // p_filesz
michael@0:     .Append(endianness(), addr_size_, filesz)
michael@0:     // p_memsz
michael@0:     .Append(endianness(), addr_size_, memsz);
michael@0: 
michael@0:   if (addr_size_ == 4) {
michael@0:     // p_flags
michael@0:     program_header_table_.D32(flags);
michael@0:   }
michael@0: 
michael@0:   // p_align
michael@0:   program_header_table_.Append(endianness(), addr_size_, 0);
michael@0: }
michael@0: 
michael@0: void ELF::Finish() {
michael@0:   // Add the section header string table at the end.
michael@0:   section_header_string_index_ = section_count_;
michael@0:   //printf(".shstrtab size: %ld\n", section_header_strings_.Size());
michael@0:   AddSection(".shstrtab", section_header_strings_, SHT_STRTAB);
michael@0:   //printf("section_count_: %ld, sections_.size(): %ld\n",
michael@0:   //     section_count_, sections_.size());
michael@0:   if (program_count_) {
michael@0:     Mark(&program_header_label_);
michael@0:     Append(program_header_table_);
michael@0:   } else {
michael@0:     program_header_label_ = 0;
michael@0:   }
michael@0: 
michael@0:   for (vector<ElfSection>::iterator it = sections_.begin();
michael@0:        it < sections_.end(); ++it) {
michael@0:     AppendSection(*it);
michael@0:   }
michael@0:   section_count_label_ = section_count_;
michael@0:   program_count_label_ = program_count_;
michael@0: 
michael@0:   // Section header table starts here.
michael@0:   Mark(&section_header_label_);
michael@0:   Append(section_header_table_);
michael@0: }
michael@0: 
michael@0: SymbolTable::SymbolTable(Endianness endianness,
michael@0:                          size_t addr_size,
michael@0:                          StringTable& table) : Section(endianness),
michael@0:                                                addr_size_(addr_size),
michael@0:                                                table_(table) {
michael@0:   assert(addr_size_ == 4 || addr_size_ == 8);
michael@0: }
michael@0: 
michael@0: void SymbolTable::AddSymbol(const string& name, uint32_t value,
michael@0:                             uint32_t size, unsigned info, uint16_t shndx) {
michael@0:   assert(addr_size_ == 4);
michael@0:   D32(table_.Add(name));
michael@0:   D32(value);
michael@0:   D32(size);
michael@0:   D8(info);
michael@0:   D8(0); // other
michael@0:   D16(shndx);
michael@0: }
michael@0: 
michael@0: void SymbolTable::AddSymbol(const string& name, uint64_t value,
michael@0:                             uint64_t size, unsigned info, uint16_t shndx) {
michael@0:   assert(addr_size_ == 8);
michael@0:   D32(table_.Add(name));
michael@0:   D8(info);
michael@0:   D8(0); // other
michael@0:   D16(shndx);
michael@0:   D64(value);
michael@0:   D64(size);
michael@0: }
michael@0: 
michael@0: void Notes::AddNote(int type, const string &name, const uint8_t* desc_bytes,
michael@0:                     size_t desc_size) {
michael@0:   // Elf32_Nhdr and Elf64_Nhdr are exactly the same.
michael@0:   Elf32_Nhdr note_header;
michael@0:   memset(&note_header, 0, sizeof(note_header));
michael@0:   note_header.n_namesz = name.length() + 1;
michael@0:   note_header.n_descsz = desc_size;
michael@0:   note_header.n_type = type;
michael@0: 
michael@0:   Append(reinterpret_cast<const uint8_t*>(&note_header),
michael@0:          sizeof(note_header));
michael@0:   AppendCString(name);
michael@0:   Align(4);
michael@0:   Append(desc_bytes, desc_size);
michael@0:   Align(4);
michael@0: }
michael@0: 
michael@0: }  // namespace synth_elf
michael@0: }  // namespace google_breakpad