public MainItem(NsoHeader nsoHeader, SectionItem parentItem, DirectoryEntryEx directoryEntry)
: base(parentItem, directoryEntry)
{
ParentItem = parentItem ?? throw new ArgumentNullException(nameof(parentItem));
NsoHeader = nsoHeader;
}
public static byte[] ConvertElfToNso(ReadOnlySpan <byte> elf)
{
if (elf.Length < Elf64Ehdr.Length)
{
throw new ArgumentException("Length of ELF data is less than the ELF header", nameof(elf));
}
var header = new Elf64Ehdr(elf);
if (header.Machine != ElfConstants.EM_AARCH64)
{
throw new ArgumentException("ELF data must have machine of AArch64", nameof(elf));
}
var phEnd = header.PhOff + (ulong)header.PHNum * Elf64Phdr.Length;
if (phEnd < header.PhOff || phEnd > (ulong)elf.Length)
{
throw new ArgumentException("Physical header address outside of file", nameof(elf));
}
using var sha256 = SHA256.Create();
var nsoHeader = new NsoHeader();
var compressedBuffers = new List <byte[]>(3);
uint fileOffset = NsoHeader.Length;
int j = 0;
for (int i = 0; i < 3; i++)
{
Elf64Phdr phdr = null;
while (j < header.PHNum)
{
var phOffset = (long)header.PhOff + j++ *Elf64Phdr.Length;
var current = new Elf64Phdr(elf.Slice((int)phOffset, header.PHEntSize));
if (current.Type == ElfConstants.PT_LOAD)
{
phdr = current;
break;
}
}
if (phdr == null)
{
throw new ArgumentException("Invalid ELF: expected 3 loadable phdrs", nameof(elf));
}
nsoHeader.Segments[i].FileOffset = fileOffset;
nsoHeader.Segments[i].MemoryOffset = (uint)phdr.VAddr;
nsoHeader.Segments[i].MemorySize = (uint)phdr.FileSize;
// for .data segment this field contains bss size
if (i == 2)
{
nsoHeader.Segments[i].AlignOrTotalSz = (uint)(phdr.MemSize - phdr.FileSize);
}
else
{
nsoHeader.Segments[i].AlignOrTotalSz = 1;
}
var sectionData = elf.Slice((int)phdr.Offset, (int)phdr.FileSize);
nsoHeader.Hashes[i] = sha256.ComputeHash(sectionData.ToArray());
var compressedBuffer = new byte[LZ4Codec.MaximumOutputSize(sectionData.Length)];
var compressedLength = LZ4Codec.Encode(sectionData, compressedBuffer, LZ4Level.L00_FAST);
compressedBuffers.Add(compressedBuffer);
nsoHeader.SegmentFileSizes[i] = (uint)compressedLength;
fileOffset += (uint)compressedLength;
}
// Iterate over sections to find build id.
var currentSectionHeaderOffset = header.ShOff;
for (int i = 0; i < header.SHNum; i++)
{
var currentShHeader = new Elf64Shdr(elf.Slice((int)currentSectionHeaderOffset, header.SHEntSize));
if (currentShHeader.Type == ElfConstants.SHT_NOTE)
{
var noteData = elf.Slice((int)currentShHeader.Offset, Elf64Nhdr.Length);
var noteHeader = new Elf64Nhdr(noteData);
var noteName = elf.Slice((int)currentShHeader.Offset + Elf64Nhdr.Length, (int)noteHeader.NameSize);
var noteDesc = elf.Slice((int)currentShHeader.Offset + Elf64Nhdr.Length + (int)noteHeader.NameSize, (int)noteHeader.DescriptorSize);
var noteNameString = Encoding.ASCII.GetString(noteName.Slice(0, 4).ToArray());
if (noteHeader.Type == ElfConstants.NT_GNU_BUILD_ID && noteHeader.NameSize == 4 && noteNameString == "GNU\0")
{
var buildIdSize = noteHeader.DescriptorSize;
if (buildIdSize > 0x20)
{
buildIdSize = 0x20;
}
noteDesc.Slice(0, (int)buildIdSize).CopyTo(nsoHeader.BuildId);
}
}
currentSectionHeaderOffset += header.SHEntSize;
}
var headerData = nsoHeader.ToByteArray();
var buffer = new List <byte>(headerData.Length + nsoHeader.SegmentFileSizes.Cast <int>().Sum());
buffer.AddRange(headerData);
for (int i = 0; i < nsoHeader.SegmentFileSizes.Length; i++)
{
buffer.AddRange(compressedBuffers[i].Take((int)nsoHeader.SegmentFileSizes[i]));
}
return(buffer.ToArray());
}
