1 files changed, 174 insertions, 0 deletions
diff --git a/src/common/linux/synth_elf.cc b/src/common/linux/synth_elf.cc
new file mode 100644
index 00000000..8f8aad32
--- /dev/null
+++ b/src/common/linux/synth_elf.cc
@@ -0,0 +1,174 @@
+#include "common/linux/synth_elf.h"
+
+#include <assert.h>
+#include <elf.h>
+#include <stdio.h>
+
+namespace google_breakpad {
+namespace synth_elf {
+
+ELF::ELF(uint16_t machine,
+         uint8_t file_class,
+         Endianness endianness)
+  : Section(endianness),
+    addr_size_(file_class == ELFCLASS64 ? 8 : 4),
+    program_count_(0),
+    section_count_(0),
+    section_header_table_(endianness),
+    section_header_strings_(endianness) {
+  // Could add support for more machine types here if needed.
+  assert(machine == EM_386 ||
+         machine == EM_X86_64 ||
+         machine == EM_ARM);
+  assert(file_class == ELFCLASS32 || file_class == ELFCLASS64);
+
+  start() = 0;
+  // Add ELF header
+  // e_ident
+  // EI_MAG0...EI_MAG3
+  D8(ELFMAG0);
+  D8(ELFMAG1);
+  D8(ELFMAG2);
+  D8(ELFMAG3);
+  // EI_CLASS
+  D8(file_class);
+  // EI_DATA
+  D8(endianness == kLittleEndian ? ELFDATA2LSB : ELFDATA2MSB);
+  // EI_VERSION
+  D8(EV_CURRENT);
+  // EI_OSABI
+  D8(ELFOSABI_SYSV);
+  // EI_ABIVERSION
+  D8(0);
+  // EI_PAD
+  Append(7, 0);
+  assert(Size() == EI_NIDENT);
+
+  // e_type
+  D16(ET_EXEC);  //TODO: allow passing ET_DYN?
+  // e_machine
+  D16(machine);
+  // e_version
+  D32(EV_CURRENT);
+  // e_entry
+  Append(endianness, addr_size_, 0);
+  // e_phoff
+  Append(endianness, addr_size_, program_header_label_);
+  // e_shoff
+  Append(endianness, addr_size_, section_header_label_);
+  // e_flags
+  D32(0);
+  // e_ehsize
+  D16(addr_size_ == 8 ? sizeof(Elf64_Ehdr) : sizeof(Elf32_Ehdr));
+  // e_phentsize
+  D16(addr_size_ == 8 ? sizeof(Elf64_Phdr) : sizeof(Elf32_Phdr));
+  // e_phnum
+  D16(program_count_label_);
+  // e_shentsize
+  D16(addr_size_ == 8 ? sizeof(Elf64_Shdr) : sizeof(Elf32_Shdr));
+  // e_shnum
+  D16(section_count_label_);
+  // e_shstrndx
+  D16(section_header_string_index_);
+
+  // Add an empty section for SHN_UNDEF.
+  Section shn_undef;
+  AddSection("", shn_undef, SHT_NULL);
+}
+
+int ELF::AddSection(const string& name, const Section& section,
+                    uint32_t type, uint32_t flags, uint64_t addr,
+                    uint32_t link, uint64_t entsize, uint64_t offset) {
+  Label offset_label;
+  Label string_label(section_header_strings_.Add(name));
+  size_t size = section.Size();
+
+  int index = section_count_;
+  ++section_count_;
+
+  section_header_table_
+    // sh_name
+    .D32(string_label)
+    // sh_type
+    .D32(type)
+    // sh_flags
+    .Append(endianness(), addr_size_, flags)
+    // sh_addr
+    .Append(endianness(), addr_size_, addr)
+    // sh_offset
+    .Append(endianness(), addr_size_, offset_label)
+    // sh_size
+    .Append(endianness(), addr_size_, size)
+    // sh_link
+    .D32(link)
+    // sh_info
+    .D32(0)
+    // sh_addralign
+    .Append(endianness(), addr_size_, 0)
+    // sh_entsize
+    .Append(endianness(), addr_size_, entsize);
+
+  // NULL and NOBITS sections have no content, so they
+  // don't need to be written to the file.
+  if (type == SHT_NULL) {
+    offset_label = 0;
+  } else if (type == SHT_NOBITS) {
+    offset_label = offset;
+  } else {
+    Mark(&offset_label);
+    Append(section);
+    Align(4);
+  }
+  return index;
+}
+
+void ELF::Finish() {
+  // Add the section header string table at the end.
+  section_header_string_index_ = section_count_;
+  //printf(".shstrtab size: %ld\n", section_header_strings_.Size());
+  AddSection(".shstrtab", section_header_strings_, SHT_STRTAB);
+  //printf("section_count_: %ld, sections_.size(): %ld\n",
+  //     section_count_, sections_.size());
+  section_count_label_ = section_count_;
+  program_count_label_ = program_count_;
+  // TODO:  allow adding entries to program header table
+  program_header_label_ = 0;
+
+  // Section header table starts here.
+  Mark(&section_header_label_);
+  Append(section_header_table_);
+}
+
+SymbolTable::SymbolTable(Endianness endianness,
+                         size_t addr_size,
+                         StringTable& table) : Section(endianness),
+                                               addr_size_(addr_size),
+                                               table_(table) {
+  assert(addr_size_ == 4 || addr_size_ == 8);
+}
+
+void SymbolTable::AddSymbol(const string& name, uint32_t value,
+                            uint32_t size, unsigned info, uint16_t shndx) {
+  assert(addr_size_ == 4);
+  D32(table_.Add(name));
+  D32(value);
+  D32(size);
+  D8(info);
+  D8(0); // other
+  D16(shndx);
+}
+
+void SymbolTable::AddSymbol(const string& name, uint64_t value,
+                            uint64_t size, unsigned info, uint16_t shndx) {
+  assert(addr_size_ == 8);
+  D32(table_.Add(name));
+  D8(info);
+  D8(0); // other
+  D16(shndx);
+  D64(value);
+  D64(size);
+}
+
+}  // namespace synth_elf
+}  // namespace google_breakpad
+