Add some unit tests for Linux WriteSymbolFile

src/common/linux/synth_elf.cc

+#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,
+         Endianness endianness)
+  : Section(endianness),
+    addr_size_(machine == EM_X86_64 ? 8 : 4),

[jimb, 2011/07/05 19:21:58]

There really should be an explicit 'file class' argument to the constructor,
ELFCLASS32 or ELFCLASS64, instead of inferring the class this way.

[Ted Mielczarek, 2011/07/06 15:45:08]

I kind of just wanted it to be easy for consumers to use, since it's just
testing code. Having to specify both the machine and the elfclass seemed
redundant when they have to match anyway. I can change it, it's not a big deal.

+    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);
+
+  start() = 0;
+  // Add ELF header
+  // e_ident
+  // EI_MAG0...EI_MAG3
+  D8(ELFMAG0);
+  D8(ELFMAG1);
+  D8(ELFMAG2);
+  D8(ELFMAG3);
+  // EI_CLASS
+  D8(addr_size_ == 4 ? ELFCLASS32 : ELFCLASS64);
+  // 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
+