protected static void AddMetadata(ElfFile file, InsomniaAssemblyMetadata metadata)
{
file.Strings.SaveString($".wasm-version::{metadata.Version}");
file.Strings.SaveString($".wasm-timestamp::{metadata.Timestamp.ToUnixTimeSeconds()}");
file.Strings.SaveString($".wasm-framework::{metadata.TargetFramework}");
file.Strings.SaveString($".other-len::{metadata.OtherMeta.Count}");
var index = 0;
foreach (var(k, v) in metadata.OtherMeta)
{
file.Strings.SaveString($".other-{index++}::{k}\a{v}");
}
}
protected internal static void WriteElf(byte[] ilCode, Stream stream, InsomniaAssemblyMetadata meta)
{
using var writer = new BinaryWriter(stream);
var file = new ElfFile();
file.Sections.Add(new ElfSection());
AddCode(file, ilCode);
AddMetadata(file, meta);
var sectionsStringsIndex = file.AddStringsSection();
const int headerSize = 0x34;
const int segmentsOffset = headerSize;
const int segmentEntrySize = 0x20;
var dataOffset = (uint)(segmentsOffset + file.Segments.Count * segmentEntrySize);
var sectionsOffset = dataOffset + file.Data.Length;
var header = new ElfHeader
{
Identification =
{
Magic = new[] { (char)0x7f, 'E', 'L', 'F' },
FileClass = ElfFileClass.Elf32,
DataType = ElfDataType.Lsb,
Version = 1,
},
Type = ElfType.SharedObject,
Machine = 0x0,
Version = 1,
Entry = 0x0,
ProgramHeaderOffset = segmentsOffset,
SectionHeaderOffset = (uint)sectionsOffset,
Flags = 0x84,
ElfHeaderSize = headerSize,
ProgramHeaderEntrySize = segmentEntrySize,
ProgramHeaderCount = (ushort)file.Segments.Count,
SectionHeaderEntrySize = 0x28,
SectionHeaderCount = (ushort)file.Sections.Count,
StringSectionIndex = (ushort)sectionsStringsIndex
};
writer.WriteElf32(header);
foreach (var segment in file.Segments)
{
var cloned = segment;
cloned.Offset += dataOffset;
writer.WriteElf32(cloned);
}
writer.Write(file.Data.ToArray());
var offset = 0u;
foreach (var section in file.Sections)
{
var cloned = section;
if (section.Type != ElfSectionType.Null)
{
cloned.Offset += dataOffset;
}
if (cloned.Type == ElfSectionType.ProgBits)
{
offset = cloned.Offset;
}
writer.WriteElf32(cloned);
}
writer.Write((uint)ilCode.Length - 17);
writer.Write(offset + 17);
}
