private void WriteElf64Segment(ElfProgramHeader ph, System.IO.BinaryWriter w)
{
throw new NotImplementedException();
}
protected override void Write(System.IO.BinaryWriter w)
{
Init();
// First, build a list of output sections
List<SectionHeader> osects = new List<SectionHeader>();
Dictionary<ISection, int> osect_map = new Dictionary<ISection, int>();
osects.Add(new NullSection());
StringSection strtab = new StringSection();
StringSection shstrtab = new StringSection();
foreach(var sect in sections)
{
SectionHeader sh = new SectionHeader();
sh.sh_name = AllocateString(sect.Name, shstrtab);
if (sect.HasData)
sh.sh_type = 1;
else
sh.sh_type = 8;
sh.sh_flags = 0;
if (sect.IsWriteable)
sh.sh_flags |= 0x1;
if (sect.IsAlloc)
sh.sh_flags |= 0x2;
if (sect.IsExecutable)
sh.sh_flags |= 0x4;
sh.sh_addr = sect.LoadAddress;
sh.sh_size = sect.Length;
sh.sh_link = 0;
sh.sh_info = 0;
sh.sh_addralign = sect.AddrAlign;
sh.sh_entsize = 0;
osect_map[sect] = osects.Count;
osects.Add(sh);
}
strtab.sh_name = AllocateString(".strtab", shstrtab);
int strtab_idx = osects.Count;
osects.Add(strtab);
shstrtab.sh_name = AllocateString(".shstrtab", shstrtab);
int shstrtab_idx = osects.Count;
e_shstrndx = shstrtab_idx;
osects.Add(shstrtab);
SectionHeader symtab = new SectionHeader();
symtab.sh_name = AllocateString(".symtab", shstrtab);
symtab.sh_link = strtab_idx;
symtab.sh_type = 2;
int symtab_idx = osects.Count;
osects.Add(symtab);
// Build symbol table
List<ElfSymbol> osyms = new List<ElfSymbol>();
osyms.Add(new ElfSymbol());
Dictionary<ISymbol, int> sym_map = new Dictionary<ISymbol, int>();
// Add local symbols first
foreach(var sym in symbols)
{
if (sym.Type == SymbolType.Local)
AddSymbol(sym, strtab, osyms, sym_map, osect_map);
}
int last_local = osyms.Count;
foreach(var sym in symbols)
{
if (sym.Type != SymbolType.Local)
AddSymbol(sym, strtab, osyms, sym_map, osect_map);
}
symtab.sh_info = last_local;
// Write out file header
// e_ident
w.Write((byte)0x7f);
w.Write((byte)'E');
w.Write((byte)'L');
w.Write((byte)'F');
w.Write((byte)ec);
w.Write((byte)ed);
w.Write((byte)1);
for (int i = 0; i < 9; i++)
w.Write((byte)0);
// store fh_start because we will re-write the header later
int fh_start = (int)w.BaseStream.Position;
switch(ec)
{
case ElfClass.ELFCLASS32:
WriteElf32FileHeader(w);
break;
case ElfClass.ELFCLASS64:
WriteElf64FileHeader(w);
break;
default:
throw new Exception("Invalid ELF class");
}
// Now write out the section data
foreach(var s in sections)
{
// align up to addralign
var sh = osects[osect_map[s]];
if (sh.sh_addralign != 0)
{
while ((w.BaseStream.Position % sh.sh_addralign) != 0)
w.Write((byte)0);
}
sh.sh_offset = w.BaseStream.Position;
if (s.HasData == false)
continue;
// write out data
foreach (byte b in s.Data)
w.Write(b);
}
// Write out string tables
while ((w.BaseStream.Position % 16) != 0)
w.Write((byte)0);
strtab.sh_offset = w.BaseStream.Position;
foreach (byte b in strtab.oput)
w.Write(b);
strtab.sh_size = strtab.oput.Count;
while ((w.BaseStream.Position % 16) != 0)
w.Write((byte)0);
shstrtab.sh_offset = w.BaseStream.Position;
foreach (byte b in shstrtab.oput)
w.Write(b);
shstrtab.sh_size = shstrtab.oput.Count;
// Write out symbol table
while ((w.BaseStream.Position % 16) != 0)
w.Write((byte)0);
symtab.sh_offset = w.BaseStream.Position;
foreach (var sym in osyms)
{
switch (ec)
{
case ElfClass.ELFCLASS32:
WriteElf32Symbol(sym, w);
break;
case ElfClass.ELFCLASS64:
WriteElf64Symbol(sym, w);
break;
}
}
// Fill in file type specific details in various structures
switch(ec)
{
case ElfClass.ELFCLASS32:
symtab.sh_entsize = 16;
symtab.sh_size = osyms.Count * symtab.sh_entsize;
e_shentsize = 40;
e_phentsize = 32;
break;
case ElfClass.ELFCLASS64:
throw new NotImplementedException();
}
// Write out section header table
while ((w.BaseStream.Position % 16) != 0)
w.Write((byte)0);
e_shoff = w.BaseStream.Position;
foreach(var sect in osects)
{
switch(ec)
{
case ElfClass.ELFCLASS32:
WriteElf32Section(sect, w);
break;
case ElfClass.ELFCLASS64:
WriteElf64Section(sect, w);
break;
}
}
// Write program headers
e_phnum = 0;
if (IsExecutable)
{
while ((w.BaseStream.Position % 16) != 0)
w.Write((byte)0);
e_phoff = w.BaseStream.Position;
foreach (var sect in sections)
{
ElfProgramHeader ph = new ElfProgramHeader();
ph.p_type = ElfProgramHeader.PT_LOAD;
ph.p_offset = (ulong)osects[osect_map[sect]].sh_offset;
ph.p_vaddr = sect.LoadAddress;
ph.p_paddr = 0;
ph.p_filesz = sect.HasData ? (ulong)sect.Data.Count : 0UL;
ph.p_memsz = (ulong)sect.Length;
ph.p_flags = 0;
if (sect.IsExecutable)
ph.p_flags |= ElfProgramHeader.PF_X;
if (sect.IsWriteable)
ph.p_flags |= ElfProgramHeader.PF_W;
ph.p_flags |= ElfProgramHeader.PF_R;
ph.p_align = (ulong)sect.AddrAlign;
if (ph.p_memsz != 0)
{
switch (ec)
{
case ElfClass.ELFCLASS32:
WriteElf32Segment(ph, w);
break;
case ElfClass.ELFCLASS64:
WriteElf64Segment(ph, w);
break;
}
e_phnum++;
}
}
}
if (e_phnum == 0)
e_phoff = 0;
// Rewrite file header
e_shnum = osects.Count;
if (is_exec)
e_type = 2;
else
e_type = 1;
if(EntryPoint != null && IsExecutable)
{
var s = FindSymbol(EntryPoint);
if (s != null && s.DefinedIn != null)
e_entry = s.Offset + s.DefinedIn.LoadAddress;
else
{
// default to offset 0x0 in text
var sect = FindSection(".text");
if(sect == null)
{
// default to 0x0
Console.WriteLine("Entry point " + EntryPoint +
" not found, defaulting to 0x0");
e_entry = 0;
}
else
{
Console.WriteLine("Entry point " + EntryPoint +
" not found, defaulting to 0x" +
sect.LoadAddress.ToString("X"));
e_entry = sect.LoadAddress;
}
}
}
int cur_pos = (int)w.BaseStream.Position;
w.Seek(fh_start, System.IO.SeekOrigin.Begin);
switch(ec)
{
case ElfClass.ELFCLASS32:
WriteElf32FileHeader(w);
break;
case ElfClass.ELFCLASS64:
WriteElf64FileHeader(w);
break;
}
w.Seek(cur_pos, System.IO.SeekOrigin.Begin);
}
private void WriteElf32Segment(ElfProgramHeader ph, System.IO.BinaryWriter w)
{
w.Write((uint)ph.p_type);
w.Write((uint)ph.p_offset);
w.Write((uint)ph.p_vaddr);
w.Write((uint)ph.p_paddr);
w.Write((uint)ph.p_filesz);
w.Write((uint)ph.p_memsz);
w.Write((uint)ph.p_flags);
w.Write((uint)ph.p_align);
}
